JP6305124B2 - 2-stroke engine cylinder lubrication system - Google Patents

Description

  The present invention relates to a cylinder lubrication device for a two-stroke engine, and more particularly to a cylinder lubrication device for a two-stroke engine in which a lubricating oil supply hole is provided on the inner peripheral surface of a cylinder.

  2. Description of the Related Art Conventionally, in a two-stroke engine, a scavenging port that connects a side portion of a cylinder and a crank chamber is formed. The scavenging port is opened and closed according to the position of the piston that reciprocates in the cylinder, communicates with the combustion chamber at the top of the cylinder when the piston is near bottom dead center, and the combustion chamber when the piston is near top dead center Communication with is interrupted. An air-fuel mixture containing fuel is supplied from the crank chamber to the cylinder through the scavenging port.

  By the way, as an engine lubrication system, there is mixed fuel lubrication in which a mixed fuel obtained by previously mixing a lubricating oil with a fuel is used, and lubrication is performed with the mixed fuel. However, since the mixed fuel mixed with the lubricating oil is used, the lubricating oil burns together with the fuel, and the consumption of the lubricating oil increases, which is uneconomical. In addition, unburned hydrocarbons ( There is a disadvantage that HC) increases.

  On the other hand, there is an external oil supply type that supplies lubricating oil from the outside using a dedicated pipe without using mixed fuel. However, in a two-stroke engine that performs pre-compression in the crank chamber, the lubricating oil that lubricates the cylinder sliding portion drops into the crank chamber and is agitated by the crank throw or connecting rod, and therefore flows easily into the combustion chamber and burns. In this respect, there is no difference from the mixed fuel lubrication, and there is a problem that the consumption amount of the lubricating oil and the unburned HC in the exhaust gas are larger than those of the engine in which the intake air is directly sent to the combustion chamber by the valve operating mechanism.

  As a technique for reducing the amount of lubricating oil in a 2-stroke engine, in an external oil supply type engine that supplies lubricating oil to the inner peripheral surface of a cylinder, a plurality of oil supply holes that are opened in the circumferential direction of the inner peripheral surface of the cylinder are provided. An invention in which an oil retaining groove that communicates with the oil supply hole and extends obliquely in the same direction as the direction of the scavenging swirl is known (see Patent Document 1).

JP 2003-286816 A

  However, the technique of the above-mentioned patent document 1 supplies lubricating oil at an appropriate timing with a dedicated injection device, and the lubrication device becomes complicated by the installation of the injection device, and the manufacturing cost also increases. Therefore, a lubrication device that can lubricate a cylinder with a simpler configuration is desired particularly for a small two-stroke engine, and the present applicant is directed to a portion below the top ring of the piston located at the bottom dead center. A plurality of oil supply holes are formed in the cylinder so as to open, and the plurality of oil supply holes are configured to increase the amount of lubricating oil supplied on the thrust side and the anti-thrust side compared to other parts. This is proposed as Japanese Patent Application No. 2013-271037.

  According to this configuration, the arrangement of the plurality of oil supply holes opened in the inner peripheral surface of the cylinder is made narrower than the other portions on the thrust side and the anti-thrust side from the center of the piston, so Since a large amount of lubricating oil is supplied to the thrust side and an excessive amount of lubricating oil is suppressed from being supplied to unnecessary portions, the entire amount of lubricating oil can be reduced. However, since the lubricating oil is burned and consumed in the two-stroke engine, it is desirable to further reduce the consumption of the lubricating oil if the lubricating performance is the same.

  In view of such a background, it is an object of the present invention to provide a cylinder lubrication device for a two-stroke engine capable of effectively performing lubrication with a small amount of lubricating oil.

  In order to solve the above-mentioned problems, the present invention is directed to the cylinder axis (A) substantially in the vertical direction, connected to the lubricating oil supply means (76), and opened to the inner peripheral surface (22A) of the cylinder (22). A cylinder lubricating device of a two-stroke engine (E) having a lubricating oil supply hole (74), which is provided so as to partition the crank chamber (2A) from the cylinder (22) side and surrounds the connecting rod (26). It has the wall (71) which defines opening (71C), It is characterized by the above-mentioned.

  According to this configuration, the lubricating oil supplied from the lubricating oil supply hole to the cylinder inner peripheral surface falls into the crankcase due to the movement of the piston to the crankcase side, but is provided so as to partition the crank chamber from the cylinder side. It is captured by the wall. Lubricating oil collected on the upper surface of the wall can be dripped from the opening provided in the wall toward the part that needs lubrication at the large end of the connecting rod, and it is possible to supply a small amount without supplying a large amount of lubricating oil. Lubrication can be performed effectively.

  The opening (71C) may be provided so as to be close to the connecting rod large end (26A).

  According to this configuration, the lubricating oil can be dripped concentrated on the connecting rod large end, that is, the bearing of the crankpin.

  The upper surface (71A) of the wall (71) may be inclined downward toward the opening (71C).

  According to this configuration, the lubricating oil flowing down the upper surface of the wall can be quickly collected toward the opening, and the necessary amount of lubricating oil to the large end of the connecting rod can be secured without increasing the amount of lubricating oil supplied. obtain.

  Further, the opening (71C) may have a long shape in a direction perpendicular to the crankshaft (8) when viewed from the axis (A) direction of the cylinder (22).

  According to this configuration, the opening can be made as narrow as possible without interfering with the swinging range of the connecting rod, and the area of the upper surface of the wall can be increased accordingly. The amount of oil can be increased.

  The upper surface (71A) of the wall (71) may be formed to be the lowest at the central portion (71B) in the direction along the long side of the opening (71C).

  According to this configuration, since the lubricating oil captured by the wall is collected in the central portion in the direction along the long side of the opening on the upper surface of the wall, the lubricating oil can be dripped intensively from the central portion, Lubricating oil can be dripped at the large end of the connecting rod without being blown away by wind pressure due to rotation of the crankshaft.

  As described above, according to the present invention, the lubricating oil can be collected on the upper surface of the wall provided so as to partition the crank chamber from the cylinder side, and the collected lubricating oil can be collected from the opening provided on the wall to the large end of the connecting rod. Therefore, the lubricant can be effectively lubricated with a small supply amount without supplying a large amount of lubricating oil.

The longitudinal cross-sectional view of the engine which concerns on embodiment II-II sectional view of FIG. 1 is an enlarged cross-sectional view of the main portion of FIG. 1 showing a collar portion according to the present invention. The principal part enlarged plan view which shows the opening part of the collar part seen in the arrow IV line direction of FIG.

  Hereinafter, an embodiment in which the present invention is applied to a uniflow single-cylinder two-stroke engine (hereinafter referred to as engine E) will be described in detail with reference to the drawings.

(Schematic configuration of the engine)
As shown in FIGS. 1 and 2, the engine body 1 of the engine E includes a crankcase 2 that defines a crank chamber 2 </ b> A therein, a cylinder block 3 joined to the top of the crankcase 2, and a cylinder block 3. A cylinder head 4 joined to the upper part and a head cover 5 joined to the upper part of the cylinder head 4 and defining an upper valve chamber 6 between the cylinder head 4 and the cylinder head 4.

  As shown in FIG. 2, the crankcase 2 is constituted by a pair of crankcase halves that are divided into left and right by a vertically extending surface (a surface passing through the cylinder axis A). The left and right crankcase halves are fastened together by bolts to form a crank chamber 2A between the halves. A crankshaft 8 is rotatably supported on the left and right side walls 2B, 2C of the crankcase 2 via a bearing 7.

  The crankshaft 8 is supported at a position eccentric from the journal 8A by a pair of journals 8A supported by the side walls 2B and 2C of the crankcase 2, a pair of webs 8B provided between the journals 8A, and the webs 8B. And a crankpin 8C.

  The end plate 11 is fastened to the outer surface side of the right side wall 2C. The end plate 11 is fastened to the outer surface of the right side wall 2C at the peripheral edge, and forms a lower valve chamber 12 between the end plate 11 and the right side wall 2C. The left end portion 8D of the crankshaft 8 extends leftward through the left side wall 2B of the crankcase 2. The right end portion 8E of the crankshaft 8 extends rightward through the right side wall 2C of the crankcase 2 and the end plate 11. A seal member 13 for ensuring airtightness of the crank chamber 2A is provided at a portion where the left end portion 8D of the crankshaft 8 penetrates the left side wall 2B and a portion where the right end portion 8E penetrates the end plate 11, respectively.

  A first sleeve receiving hole 16 having a circular cross section is formed in the upper portion of the crankcase 2 and extends in the vertical direction.

  The cylinder block 3 extends vertically and is joined to the upper end surface of the crankcase 2 at the lower end surface. The cylinder block 3 is formed with a second sleeve receiving hole 18 penetrating vertically from the upper end surface to the lower end surface. The second sleeve receiving hole 18 is a stepped hole having a circular cross section whose upper part is enlarged in a stepped manner with respect to the lower part, and has an annular shoulder surface 18A facing upward at the boundary between the upper part and the lower part. The lower end opening of the second sleeve receiving hole 18 faces the upper end opening of the first sleeve receiving hole 16 of the cylinder block 3 coaxially and communicates with each other. The inner diameters of the lower portions of the first sleeve receiving hole 16 and the second sleeve receiving hole 18 are equal to form a continuous hole.

  Cylindrical cylinder sleeves 19 are fixed to the first and second sleeve receiving holes 16 and 18. The cylinder sleeve 19 has an annular convex portion 21 projecting radially outward on the outer peripheral portion. When the convex portion 21 abuts against the shoulder surface 18A, the position of the cylinder sleeve 19 with respect to the first and second sleeve receiving holes 16 and 18 is determined. The lower end of the cylinder sleeve 19 protrudes downward from the lower end opening of the first sleeve receiving hole 16 and is a protruding end inside the crank chamber 2A. The upper end of the cylinder sleeve 19 is disposed at a position flush with the upper end surface of the cylinder block 3 and abuts on the lower end surface of the cylinder head 4 joined to the cylinder block 3. Accordingly, the cylinder sleeve 19 is sandwiched between the shoulder surface 18A and the lower surface of the cylinder head 4, and the position is determined in the direction of the cylinder axis A. An inner hole of the cylinder sleeve 19 forms a cylinder 22.

  The piston 22 is received by the cylinder 22 so as to be able to reciprocate. The piston 23 has a piston pin 23 </ b> A that extends parallel to the crankshaft 8. A small end portion (26C) of a connecting rod 26 is rotatably supported by the piston pin 23A via a bearing 24. The large end portion (26A) of the connecting rod 26 is rotatably supported by the crankpin 8C via the bearing 25. The piston 23 and the crankshaft 8 are connected by the connecting rod 26, whereby the reciprocating motion of the piston 23 is converted into the rotational motion of the crankshaft 8.

  As shown in FIGS. 1 and 2, a hemispherical combustion chamber recess 28 is formed at a position corresponding to the cylinder sleeve 19 on the lower end surface of the cylinder head 4. The combustion chamber recess 28 forms a combustion chamber 29 between the top surface of the piston 23 and serves as the upper end of the cylinder 22.

  A spark plug 30 is provided on the cylinder head 4 so as to face the combustion chamber 29. Further, the cylinder head 4 is formed with an exhaust port 31 that opens at the top of the combustion chamber 29, and is provided with a poppet type exhaust valve 32 that opens and closes the exhaust port 31. The exhaust valve 32 has a stem end disposed in the upper valve chamber 6 and is urged in a closing direction by a valve spring 33. The exhaust valve 32 is driven to open and close by the valve mechanism 34 in synchronization with the rotation of the crankshaft 8.

  As shown in FIG. 2, the valve operating mechanism 34 is driven by the camshaft 41 that rotates according to the rotation of the crankshaft 8, the push rod 42 that is driven to advance and retreat by the camshaft 41, and the exhaust valve 42. And a rocker arm 43 that pushes 32 in the opening direction. The camshaft 41 is disposed in the lower valve operating chamber 12 in parallel with the crankshaft 8. One end of the camshaft 41 is rotatably supported by the right side wall 2 </ b> C of the crankcase 2, and the other end is rotatably supported by the end plate 11. The crankshaft 8 has a crank gear 45 at a portion located in the lower valve operating chamber 12, and the camshaft 41 has a cam gear 46 that meshes with the crank gear 45. The gear ratio between the crank gear 45 and the cam gear 46 is 1: 1. The cam shaft 41 is provided with a cam 47 that is a plate cam.

  The push rod 42 is accommodated in a tubular rod case 51 whose both ends are open and retractable. The rod case 51 extends vertically and has a lower end joined to the right side wall 2C of the crankcase 2 to communicate with the lower valve chamber 12 and an upper end joined to the cylinder block 3 to communicate with the upper valve chamber 6. To do. The push rod 42 contacts the cam 47 of the camshaft 41 at the lower end, and advances and retreats according to the rotation of the camshaft 41. A roller may be provided at the lower end of the push rod 42, and the roller may be in rolling contact with the cam 47.

  The rocker arm 43 is rotatably supported by a rocker shaft 52 supported by the cylinder head 4. The rocker shaft 52 extends in a direction orthogonal to the cylinder axis A and the axis of the crankshaft 8. The rocker arm 43 has a receiving portion 43A that contacts the upper end of the push rod 42 at one end, and a screw adjuster 43B that contacts the stem end of the exhaust valve 32 at the other end.

  With the valve mechanism 34 having the above-described configuration, the exhaust valve 32 is opened once at a predetermined timing each time the crankshaft 8 rotates once.

  As shown in FIG. 1, an intake port 53 that is an opening communicating with the crank chamber 2 </ b> A is formed in the front side wall 2 </ b> D of the crankcase 2. The intake port 53 is formed so that intake air flows from the intake passage (not shown) on the left side of the drawing toward the crankshaft 8 side. The intake port 53 is provided with a reed valve 54 that allows a fluid flow from the intake port 53 side to the crank chamber 2A side, but prevents a fluid flow from the crank chamber 2A side to the intake port 53 side. Yes. The reed valve 54 is normally closed, and opens when the pressure in the crank chamber 2A decreases due to the piston 23 rising.

  A scavenging port 55 penetrating in the radial direction is formed in a portion corresponding to the inside of the first sleeve receiving hole 16 of the cylinder sleeve 19. The height dimension of the scavenging port 55 is set smaller than the height dimension of the outer peripheral surface of the piston 23. A scavenging port 56 that communicates between the crank chamber 2 </ b> A and the scavenging port 55 is formed in the upper part of the crankcase 2 and around the first sleeve receiving hole 16. The scavenging port 55 forms the downstream end of the scavenging port 56. The scavenging port 55 (scavenging port 56) is opened and closed by the reciprocating motion of the piston 23. Specifically, when the piston 23 is in a position corresponding to the scavenging port 55, the scavenging port 56 is closed by the outer periphery of the piston 23, and the lower edge of the piston 23 is above (upper) the lower edge 55 B of the scavenging port 55. When located on the dead center side), the scavenging port 56 is opened so as to communicate with the lower portion of the cylinder 22 than the piston 23, and the upper edge of the piston 23 is below the upper edge 55A of the scavenging port 55 (lower dead center). The scavenging port 56 is opened so as to communicate with the upper part of the cylinder 22 than the piston 23.

  As shown in FIG. 1, an annular oil passage forming member 60 is joined to the outer peripheral portion of the lower end portion of the cylinder sleeve 19 that has entered the crank chamber 2A. The inner peripheral surface of the oil passage forming member 60 is in surface contact with the outer peripheral surface of the cylinder sleeve 19 in the circumferential direction. As shown in FIG. 3, an annular groove 72 extending annularly in the circumferential direction is formed on the outer peripheral surface of the cylinder sleeve 19 and facing the inner peripheral surface of the oil passage forming member 60. ing. The annular groove 72 is covered by the oil passage forming member 60 and forms an annular passage. An oil inlet hole 73 that penetrates in the radial direction and communicates with the annular groove 72 is formed in the oil passage forming member 60. An oil supply hole (lubricating oil supply hole) 74 that penetrates in the radial direction and communicates with the annular groove 72 is formed in the cylinder sleeve 19. A plurality of oil supply holes 74 are formed in the circumferential direction of the cylinder sleeve 19.

  As shown in FIG. 1, a first oil passage 64 is formed in the cylinder block 3. The first oil passage 64 has one end that opens to the side surface of the cylinder block 3 and the other end that opens to the lower end surface of the cylinder block 3. In the crankcase 2, a passage 65 extending from the scavenging port 56 to the lower end surface of the cylinder block 3 and opening the first oil passage 64 is formed. One end of a second oil passage pipe 66 that forms a second oil passage is connected to the opening end of the first oil passage 64 at the lower end surface of the cylinder block 3. The second oil passage pipe 66 extends through the passage 65 and enters the scavenging port 56, and the other end is connected to the oil inlet hole 73 of the oil passage forming member 60. Thereby, the lubricating oil pumped by the oil pump 76 as the lubricating oil supply means passes through the first oil passage 64, the second oil passage pipe 66, the oil inlet hole 73, the annular groove 72, and the oil supply hole 74 in order. Then, it is supplied to the inner wall of the cylinder sleeve 19 (the inner peripheral surface 22A of the cylinder 22).

  A fuel injection valve 68 is attached to the rear side wall 2E of the crankcase 2. The tip of the fuel injection valve 68 is disposed in the crank chamber 2A and faces the crankshaft 8 side. The fuel injection valve 68 injects fuel into the crank chamber 2A at a predetermined timing.

  As shown in FIGS. 1 and 2, on the inner surfaces of the side walls 2B to 2E of the crankcase 2, there are provided flanges 71 protruding in the directions close to each other as walls of the present invention. The flange 71 divides the crank chamber 2A from the cylinder 22 side and is disposed above the upper end (crank arm 8F) of the web 8B when the piston 23 is located at the top dead center so as not to interfere with the crankshaft 8. Is done. Further, when viewed from the axial direction of the crankshaft 8 (FIG. 1) and the direction orthogonal to the crankshaft 8 (FIG. 2), the pair of flange portions 71 define an opening 71 </ b> C at the tip thereof so as not to interfere with the connecting rod 26. Yes.

  The engine E configured as described above operates as follows after starting. Referring to FIG. 1, first, in the ascending stroke of the piston 23, the reed valve 54 is opened due to the decompression of the crank chamber 2A, and fresh air flows into the crank chamber 2A. Fuel is injected from the fuel injection valve 68 into the fresh air flowing into the crank chamber 2A, and an air-fuel mixture is generated. At the same time, the air-fuel mixture in the cylinder 22 is compressed by the piston 23. When the piston 23 is in the vicinity of the top dead center, the spark plug 30 performs spark ignition, and the fuel burns.

  Thereafter, when the piston 23 moves to the downward stroke, the reed valve 54 is closed and the air-fuel mixture in the crank chamber 2A is compressed. Before the piston 23 descends and the piston 23 opens the scavenging port 56, the exhaust valve 32 driven by the valve mechanism 34 opens the exhaust port 31. Next, when the piston 23 opens the scavenging port 55, the air-fuel mixture compressed in the crank chamber 2A flows into the cylinder 22 (combustion chamber 29) through the scavenging port 56. The already burned gas (exhaust gas) in the combustion chamber 29 is exhausted from the exhaust port 31 so as to be pushed out by the air-fuel mixture, and a part thereof remains in the combustion chamber 29 as internal EGR gas.

  When the piston 23 again moves up, the exhaust valve 32 driven by the cam 47 closes the exhaust port 31 after the piston 23 closes the scavenging port 56, and the cylinder 22 (combustion chamber 29) as the piston 23 rises. ) The air-fuel mixture inside is compressed. At the same time, the inside of the crank chamber 2A is depressurized and the air-fuel mixture is sucked from the reed valve 54.

  In this way, the engine E performs a two-cycle operation. The flow of the scavenging exhaust flowing from the scavenging port 56 to the exhaust port 31 via the cylinder 22 is a uniflow with little bending.

  In the engine E configured as described above, during the operation of the engine E, lubricating oil is supplied from the plurality of oil supply holes 74 to the inner peripheral surface 22A of the cylinder 22. As shown in FIG. 1, the lubricating oil is collected in the oil tank 75 from the oil drain passage 2G provided at the bottom of the crankcase 2 and sucked out from the oil tank 75 by the oil pump 76 to the oil supply hole 74. It is pumped towards. An oil passage forming member 77 is attached to an outer wall surface of the cylinder block 3 where the first oil passage 64 is opened, and an oil passage 77 </ b> A communicating with the first oil passage 64 is formed in the oil passage forming member 77. . The lubricating oil pumped from the oil pump 76 passes through the oil passage 77A of the oil passage forming member 77, the first oil passage 64, the passage 65, and the second oil passage pipe 66, and the oil passage shown in FIG. The oil is supplied to the oil inlet hole 73 of the forming member 60, distributed to the plurality of oil supply holes 74 via the annular groove 72, and supplied to the inner peripheral surface 22 </ b> A of the cylinder 22.

  The lubricating oil supplied from the plurality of oil supply holes 74 to the inner peripheral surface 22A of the cylinder 22 adheres to the outer peripheral surface of the piston 23 when the piston 23 is descending toward the bottom dead center. When the dead point is reached, it adheres to the outer peripheral surface of the piston 23 between the compression ring and the oil ring. The lubricating oil adhering to the outer peripheral surface of the piston 23 is pulled upward as the piston 23 rises (moves toward the combustion chamber 29 side), and the inner surface of the cylinder 23 and the outer peripheral surface of the piston 23 moving up and down in this way. Lubricate the peripheral surface 22A. The lubricating oil dripped by gravity or the lubricating oil dropped from the inner peripheral surface 22A of the cylinder 22 by the piston 23 descending (moving toward the crankshaft 8) is dropped on the upper surface 71A (on the cylinder 22 side) of the flange portion 71. Surface).

  Further, the flange portion 71 is directed from the side walls 2B to 2E of the crankcase 2 constituting the engine body 1 to the lower side of the cylinder 22 (on the crankshaft 8 side) so as to be interposed between the cylinder 22 and the crankshaft 8. The protruding end defines an opening 71C. The upper surface 71 </ b> A of the flange portion 71 is formed in a concave curved shape extending from the side portion of the cylinder 22 on the side walls 2 </ b> B to 2 </ b> E of the crankcase 2 to the lower side of the cylinder 22.

  2 and 3, the slope of the curved surface of the upper surface 71A is from the side walls 2B and 2C with respect to the surface orthogonal to the cylinder axis A (the horizontal surface when the surfaces of the side walls 2B and 2C are perpendicular). It is formed so as to be gentle as it reaches the protruding end of the flange 71, and in the vicinity of the protruding end of the flange 71 so as to be parallel to a plane orthogonal to the cylinder axis A. On the other hand, in the cross section shown by FIG. 1, the collar part 71 is curving concavely from the side walls 2D and 2E toward the center.

  As shown in FIG. 3, the portion parallel to the plane perpendicular to the cylinder axis A is the central portion along the long side of the opening 71C, and the central portion is the lowest portion of the upper surface 71A. A groove 71B is further formed in the lower portion. The groove 71B extends from an arbitrary position above the inclined surface in the direction along the axis of the crankshaft 8 on the upper surface 71A to reach the edge of the opening 71C. As a result, the lubricating oil that travels down the surface of the flange 71 is likely to collect in the groove 71B. Thereby, since lubricating oil can be dripped intensively from the groove | channel 71B, the lubricating oil dripped from the protrusion end of the collar part 71 can be made into a large grain state. Since the connecting rod large end portion 26A rotates at a high speed, there is a possibility that the lubricating oil may be blown off by the wind pressure in a fine and small particle state, but when the lubricating oil is dripped in a large particle state, it easily reaches the bearing 25 of the crankpin 8C. The lubricating oil accumulated in the lower part of the crankcase 2 is splashed by the connecting rod large end portion 26A and used for lubricating the connecting rod small end portion 26C.

  Further, at the protruding end of the flange portion 71, an R chamfering that falls from the flat portion to the crankshaft 8 side is performed, and the crankshaft 8 side is formed in a right-angle cross section. Thereby, the flow of the lubricating oil at the protruding end of the flange portion 71 is smooth, and the lubricating oil is well cut when dropped.

  Below the cylinder 22, the connecting rod 26 oscillates while the connecting rod large end portion 26 </ b> A rotates as the piston 23 reciprocates and the crankshaft 8 rotates. When viewed from the direction of the cylinder axis A, the range in which the connecting rod 26 swings in the opening 71C is indicated by S in FIG. The opening 71 </ b> C is formed in a rectangular shape surrounding the connecting rod 26 that moves in the range S. The edge corresponding to the long side of the rectangular opening 71 </ b> C is located close to the crank shaft direction end surface 26 </ b> B of the connecting rod large end portion 26 </ b> A when viewed from the direction of the cylinder axis A.

  Further, as shown in FIG. 4 as viewed from the direction of the cylinder axis A, the upper surface 71A of the flange portion 71 is formed to be the lowest at the central portion 71D in the direction along the long side of the opening 71C. . In the illustrated example, the edge corresponding to the central portion 71D of the opening 71C is located between the connecting rod large end portion 26A and the crank arm 8F (see FIGS. 2 and 3). As a result, the lubricating oil dripping from the cylinder 22 side, captured by the flange 71, and flowing down the upper surface 71A and collecting in the groove 71B, the connecting rod large end portion 26A and the crank arm 8F from the edge of the opening 71C of the central portion 71D. It can be dripped in between. Thereby, since the supply of the lubricating oil to the bearing 25 of the crankpin 8C can be performed at a pinpoint, the connecting rod large end portion 26A and the bearing 25 of the crankpin 8C can be effectively lubricated with a small amount of lubricating oil. it can.

  Further, the opening 71 </ b> C is preferably set to be as narrow as possible while ensuring the movement range S of the connecting rod 26. Accordingly, the upper surface 71A of the flange portion 71 can be widened to increase the amount of lubricating oil that can be captured as much as possible. Therefore, when the opening 71C is large or the flange portion 71 is not provided, the connecting rod is large. Lubricating oil that is not dripped between the end portion 26A and the crank arm 8F and on the bearing 25 can be reduced, and more effective lubrication can be performed. Although the crank chamber 2A is partitioned by the flange portion 71, the flow through the opening 71C in the air in the crank chamber 2A accompanying the reciprocating motion of the piston 23 is the swing range of the connecting rod 26 (S in FIG. 4). Because it is very open, it is done without any problems.

  Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to such embodiments and can be easily understood by those skilled in the art. As long as it does not deviate from the above, it can be appropriately changed. For example, the flange portion 71 is formed integrally with the crankcase 2 in the illustrated example, but may be a separate member, with one end of the plate material fixed to the side walls 2B to 2E and the other end below the cylinder 22. You may make it locate in this. In the illustrated example, the groove 71B is provided in the lowest part of the upper surface 71A of the flange 71 as a wall. However, the groove 71B is not necessarily formed, and the position where the groove 71B is provided is lowest. It may be formed in a concave shape as a whole. Further, although the OHV (Over Head Valve) format is used as the valve operating format, it is not limited to the OHV format, but may be a side valve format or an OHC (Overhead Camshaft) format, and the shape of the combustion chamber 29 is not limited to a hemispherical shape. . In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention.

2A Crank chamber 22 Cylinder 22A Inner peripheral surface 26 Connecting rod 26A Connecting rod large end 71 Hut (wall)
71A Top surface 71B Groove (center part)
71C Opening 74 Oil supply hole (lubricating oil supply hole)
76 Oil pump (lubricant supply means)
A Cylinder axis E Engine (2-stroke engine)

Claims (5)

A cylinder whose cylinder axis is generally directed in the vertical direction; a piston that moves up and down in the cylinder and projects downward from the lower end of the cylinder when positioned at a bottom dead center; and a crank chamber that communicates with the lower end of the cylinder A connecting shaft having a crankshaft provided in the crank chamber, a small end portion rotatably supported by a piston pin of the piston, and a large end portion rotatably supported by the crankpin of the crankshaft; An intake passage that opens into the crank chamber, a first one-way valve that is provided in the intake passage and allows fluid to flow toward the crank chamber, an upstream end that communicates with the crank chamber, and an inside of the cylinder has a downstream end which opens on the peripheral surface, and when the piston is located at least the bottom dead center, a combustion chamber in which the downstream end is formed above the piston And a scavenging port for passing, a cylinder lubrication system for two-stroke engines to be supplied to the combustion chamber via the scavenging port compressed gas compressed the crank chamber by downward movement of the piston,
A lubricating oil supply hole which is connected to the lubricating oil supply means and which opens to the inner peripheral surface of the cylinder;
A crankcase that defines the crank chamber so as to partition the crank chamber from the cylinder side, and has a wall that defines an opening that surrounds the connecting rod;
The opening has a long shape in a direction perpendicular to the crankshaft as viewed from the axial direction of the cylinder,
Both edges forming the long side of the opening are arranged so that the lubricating oil trapped by the upper surface of the wall is supplied to the sliding portion between the large end portion and the crank pin, as viewed from the cylinder axial direction. A cylinder lubrication device for a two-stroke engine, wherein the cylinder lubrication device is provided so as to be close to a portion.   The cylinder lubrication device for a two-stroke engine according to claim 1, wherein the upper surface of the wall is inclined downward toward the opening.   3. The cylinder lubrication device for a two-stroke engine according to claim 2, wherein an upper surface of the wall is formed so as to be lowest at a central portion in a direction along a long side of the opening.   The cylinder lubricating device according to claim 3, wherein a groove extending in an axial direction of the crankshaft and reaching an edge of the opening is formed in a lowest portion of the upper surface of the wall.   5. The cylinder according to claim 1, wherein both edges forming a long side of the opening are close to a crank axial end surface of the large end portion when viewed from the cylinder axial direction. Lubrication device.

Images