JP4692512B2 - Piston and internal combustion engine - Google Patents

Description

  The present invention relates to a piston used in an internal combustion engine, and more particularly to a piston structure in which a piston pin boss, a skirt, and a connection wall that connects the piston pin boss and the skirt are extended from the top.

  A piston used in an internal combustion engine is usually provided with a piston skirt (hereinafter simply referred to as “skirt”) in order to suppress the swinging behavior of the piston in the cylinder bore. The skirt is in sliding contact with the inner wall surface of the cylinder bore (hereinafter referred to as the cylinder wall) and is deformed by bending, thereby suppressing an increase in friction between the piston and the cylinder wall while suppressing a swinging behavior of the piston. . In addition, the piston is provided with a piston pin boss (hereinafter simply referred to as “pin boss”) into which the piston pin is fitted in order to be connected to a connecting rod (hereinafter referred to as connecting rod) via the piston pin.

  The skirt is required to be appropriately bent and deformed in order to reduce friction between the piston and the cylinder wall, and is usually formed of a thin wall body. In order to reinforce the end of the skirt, particularly in the circumferential direction of the piston (hereinafter referred to as the skirt peripheral end), the piston generally has a wall body (hereinafter referred to as a connection wall) that connects the peripheral end of the skirt and the pin boss. Is provided). These connection walls, skirts, and pin bosses are provided so as to protrude from the top of the piston in the direction of the central axis of the piston, and form a cylindrical shape.

  Further, in the piston described in Patent Document 1 below, in order to reinforce the skirt, a reinforcing rib for connecting the skirt and the pin boss is provided. By providing reinforcing ribs, the rigidity of the skirt is locally improved.

Japanese Utility Model Publication No. 2-149852

  By the way, in the expansion stroke and compression stroke of the piston, a force in the cylinder bore radial direction (hereinafter referred to as thrust force) acts between the skirt and the cylinder wall between the skirt and the cylinder wall, and the skirt reacts with the reaction force. (Hereinafter referred to as a thrust reaction force) to bend and deform. In particular, as shown in FIG. 7, in the piston 200, a central portion 41 (hereinafter referred to as a skirt central portion) in the piston circumferential direction G of the skirt 40 is deformed toward the piston central axis C side.

  When the skirt central portion 41 is elastically deformed toward the piston central axis C in this way, the stress is transmitted to the skirt peripheral end portion 42 side, and as shown by a two-dot chain line in FIG. May protrude outward in the piston radial direction R and deform. If the vicinity of the skirt peripheral end portion 42 is deformed outward in the piston radial direction R, the outer surface 42a of this portion may locally abut against the cylinder wall.

  In order to prevent this, if the vicinity of the skirt peripheral end portion 42 is made thicker than the skirt central portion 41 to improve the rigidity, the skirt 40 as a whole has the ability to elastically deform toward the piston central axis C side. This causes a problem that the friction between the piston 200 and the cylinder wall increases.

  The present invention has been made in view of the above, and without making the vicinity of the skirt peripheral end thicker than the other parts of the skirt, the piston radii outward in the vicinity of the skirt peripheral end. An object of the present invention is to provide a piston and an internal combustion engine that can suppress deformation of the engine.

In order to achieve the above object, the piston pin boss, the skirt, and the connecting wall that connects the piston pin boss and the skirt, which are used in the internal combustion engine, are extended from the top, On the piston central axis side, there is provided an inner wall for connecting connecting walls facing each other in the axial direction of the piston pin, the inner wall extending along the axial direction of the piston pin, and coupling of the inner wall and the connecting wall The portion extends along the piston axial direction, and the end of the inner wall on the skirt hem side is provided to face the skirt hem, in the piston radial direction, and the skirt has a central portion in the circumferential direction of the piston. A beam wall that connects the inner wall is provided .

  In the piston according to the present invention, the beam wall may extend from the central portion of the skirt in the circumferential direction of the piston toward the piston central axis.

  In the piston according to the present invention, the beam wall may extend along a direction orthogonal to the piston pin axial direction, and a plurality of beam walls are provided at predetermined intervals in the piston pin axial direction. Can be.

  In the piston according to the present invention, it is possible to form a guide passage surrounded by the inner wall and the skirt and capable of guiding the oil flowing in from the skirt skirt side to the top ceiling surface.

  In the piston according to the present invention, the shape of the opening on the top side of the guide passage is defined by the end on the top side of the inner wall and the connection surface connecting the inner peripheral surface of the skirt to the inner peripheral surface of the top portion. can do.

  In the piston according to the present invention, the guide passage may be partitioned by a beam wall, and a plurality of guide passages having openings on the top side and the skirt skirt side may be formed.

  In the piston according to the present invention, the pin boss can be connected to the connecting rod via the piston pin, and a notch is formed on the skirt hem side portion of the inner wall corresponding to the flange portion of the connecting rod. Can be.

  In the piston according to the present invention, the inner wall may have an arcuate shape that is convex and curved toward the piston central axis.

  The internal combustion engine according to the present invention is an internal combustion engine having the piston, and may be provided with an oil jet that injects oil toward an opening on the skirt bottom side of the guide passage.

  In the internal combustion engine according to the present invention, the piston may be partitioned by a beam wall, and a plurality of guide passages having openings on the top side and the skirt bottom side may be formed. A plurality of injection holes may be provided corresponding to the openings on the skirt skirt side of the passage.

  According to the present invention, since the inner wall for connecting the connecting walls facing each other in the axial direction of the piston pin is provided on the piston central axis side from the skirt, the central portion of the skirt is caused by the side pressure from the cylinder wall. Even if the piston is to be elastically deformed toward the center axis of the piston, it is possible to prevent the vicinity of the skirt peripheral end from being deformed outward in the piston radial direction by applying a tension to the inner wall. Thereby, it can suppress that the vicinity of a skirt peripheral end contacts a cylinder wall locally.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  First, schematic configurations of the piston and the internal combustion engine according to the present embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a configuration around a piston of an internal combustion engine. FIG. 1 schematically shows only the main part related to the present invention.

  The internal combustion engine 10 includes a cylinder block 12, a piston 20, a connecting rod 16 (hereinafter simply referred to as “connecting rod” and indicated by a two-dot chain line in the figure), and a crankshaft and cylinder head (not shown) as components constituting the engine body. Etc. A cylinder bore 14 is formed in the cylinder block 12, and the piston 20 reciprocates in the cylinder bore 14 while a piston ring described later is brought into sliding contact with an inner wall surface 15 (hereinafter referred to as a cylinder wall) of the cylinder bore 14. . The piston 20 is connected to the connecting rod 16 by a piston pin 18 so as to swing. The internal combustion engine 10 can convert the combustion load received by the piston 20 into the rotational motion of the crankshaft and output it.

  A cylinder head (not shown) is coupled to the cylinder block 12 so as to close the cylinder bore 14 so as to face the top surface 22 of the piston 20. The cylinder block 12 is formed with a crankcase (not shown) that accommodates the crankshaft so as to face a surface 26 (hereinafter referred to as a ceiling surface) on the back side of the top surface 22 of the piston 20.

  The piston 20 is inserted into the cylinder bore 14 so that the center axis (indicated by the alternate long and short dash line C in the figure) coincides with the axis of the cylinder bore 14. In the following description, the axial center of the cylinder bore 14, that is, the direction along the central axis C of the piston 20 is referred to as “piston axial direction”. Further, the radial direction of the cylinder bore 14, that is, the radial direction of the piston 20, is simply referred to as “piston radial direction” and is indicated by an arrow R in the drawing. Further, the circumferential direction of the cylinder bore 14, that is, the circumferential direction around the central axis C of the piston 20 is referred to as “piston circumferential direction”, and is indicated by an arrow G in the drawing.

  Further, the direction in which the piston 20 faces the cylinder head side in the piston axial direction is referred to as “head side” and is indicated by an arrow U in the drawing. Further, the direction in which the piston 20 faces the crankcase in the piston axial direction is referred to as “crank side” and is indicated by an arrow D in the drawing.

  Compression rings 72 and 74 and an oil ring 76 are attached to the outer peripheral surface 30 a of the top portion 30 of the piston 20 so as to be in sliding contact with the cylinder wall 15. The “top” of the piston 20 is a portion on the head side in the piston axial direction including the top surface 22.

  Next, the structure around the skirt of the piston according to the present embodiment will be described with reference to FIGS. 1-2 and 1-3. FIG. 1-2 is a bottom view of the piston as viewed from the skirt side. 1-3 is a sectional view taken along line A1-A1 of FIG. In FIG. 1-3, some outlines are omitted for easy understanding.

  The piston 20 is provided with a piston pin boss (hereinafter simply referred to as “pin boss”) that rotatably holds the piston pin 18. The pin boss 60 is formed with a piston pin hole 62 into which the piston pin 18 is inserted (hereinafter simply referred to as “pin hole”). The pin boss 60 protrudes from the ceiling surface 26 of the top portion 30 of the piston 20 toward the crank side. The pin boss 60 is provided with a pin boss rib 65 between the pin hole 62 and the top portion 30 to reinforce the pin boss 60.

  The pin boss 60 is connected to a connection wall described later in the piston circumferential direction G. The force received by the piston 20 from the top surface 22 is transmitted from the pin hole 62 of the pin boss 60 to the connecting rod 16 through the piston pin 18. In the following description, the axial direction of the pin hole 62 formed in the pin boss 60 is referred to as “piston pin axial direction” and is indicated by an arrow P in the figure.

  A skirt 40 is provided on the crank side of the top portion 30 of the piston 20 in order to suppress the swinging behavior of the piston 20 in the cylinder bore 14. The skirt 40 is provided so as to protrude from the top 30 of the piston 20 in the piston axial direction toward the crank side.

  The skirt 40 is configured by a wall that is thinner than the top 30, and an outer peripheral surface 40 a thereof faces the cylinder wall 15. An inner peripheral surface 40 c of the skirt 40 faces a small end (not shown) of the connecting rod 16. In the following description, the portion of the skirt 40 on the most crank side is indicated as “hem” of the skirt 40 and indicated by reference numeral 40 e. The skirt 40 is in sliding contact with the cylinder wall 15 at its outer peripheral surface 40 a and receives a side pressure (thrust reaction force), thereby suppressing the swinging behavior of the piston 20.

  The “skirt” is a portion of the piston 20 that is curved with the same curvature as the outer peripheral surface 30 a of the top portion 30, and an end portion in the circumferential direction of the skirt 40 (hereinafter referred to as a skirt peripheral end portion) This is indicated by reference numeral 42 in the figure. In the piston circumferential direction G, the circumferential end portion 42 of the skirt 40 is connected to a connection wall 50 described later.

  The “outer peripheral surface” means a surface of the top portion 30 and the skirt 40 of the piston 20 that faces the cylinder wall 15. On the other hand, the “inner peripheral surface” is a surface on the back side of the outer peripheral surface, and means a surface facing the central axis C side of the piston 20. In the present embodiment, the “inner peripheral surface” includes the inner peripheral surface 30 c of the top portion 30 and the inner peripheral surface 40 c of the skirt 40. “Piston inner side” means a space on the piston center axis C side from the inner peripheral surface 30 c of the top 30 and the inner peripheral surface 40 c of the skirt 40.

  The piston 20 is provided with a connection wall 50 that connects the skirt 40 and the pin boss 60. The connection wall 50 extends from the two peripheral end portions 42 on both sides of the skirt 40 in the piston circumferential direction G toward the adjacent pin bosses 60. The inner surfaces 50c of the two connection walls 50 face each other. The outer surface 50a of the connection wall 50 and the outer peripheral surface 40a of the skirt 40 are smoothly continuous. Similar to the skirt 40 and the pin boss 60, the connection wall 50 is provided so as to protrude from the top 30 in the piston axial direction toward the crank side, that is, the skirt hem 40e.

  As described above, in the piston 20, the skirt 40, the pin boss 60, and the connection wall 50 extend from the top 30 in the piston axial direction, and are coupled in the piston circumferential direction G to form a substantially cylindrical shape with a bottom. ing. In the piston 20, the thickness of the skirt 40 and the connection wall 50 is configured to be substantially uniform.

  As shown in FIG. 1-2, the piston is provided with an inner wall 44 that connects the connection walls 50 facing each other in the piston pin axial direction P on the piston center axis C side from the skirt 40. The inner wall 44 extends along the piston pin axial direction P, and both ends thereof are coupled to the connection wall 50. In the following description, a portion where the inner wall 44 and the connection wall 50 are joined is referred to as a “joint portion” and is denoted by reference numeral 54.

  As shown in FIG. 1-3, the inner wall 44 is provided so as to protrude from the top 30 of the piston 20 in the direction of the piston axis toward the crank side, that is, the skirt hem 40e. The inner wall 44 is extended so that the end 44e on the skirt hem 40e side faces the skirt 40e of the skirt 40 in the piston radial direction R. That is, the inner wall 44 extends so that the distance between the end 44e of the inner wall 44 on the skirt hem 40e side and the top surface 22 is the same as the distance between the skirt 40e of the skirt 40 and the top surface 22.

  The inner wall 44 is formed as a plate-like member along a plane defined by the piston axis direction and the piston pin axis direction P, and both ends of the piston pin axis direction P are coupled to the connection wall 50. That is, the coupling portion 54 between the inner wall 44 and the connection wall 50 extends along the piston axial direction.

  The outer surface 44 a of the inner wall 44 faces the inner peripheral surface 40 c of the skirt 40, and the inner surface 44 c of the inner wall 44 faces the pin boss 60. Inside the piston radial direction R of the skirt 40, a bottomed cavity 78 is formed by being surrounded by the outer surface 44a of the inner wall 44, the inner surface 40c of the skirt 40, and the connection surface 39 of the top 30 connecting them.

  As for the piston comprised in this way, as shown to FIGS. 1-2, the skirt 40 receives the side pressure from the cylinder wall 15, and the center part 41 (skirt center part) of the piston circumferential direction G of the skirt 40 is a piston central axis. When elastically deforming toward the C side, the vicinity of the end portion 42 (skirt peripheral end portion) of the skirt 40 in the piston circumferential direction G tends to be elastically deformed toward the outside in the piston radial direction R. That is, the space | interval of the piston pin axial direction P of the connection part 54 which continues to the skirt peripheral edge part and mutually opposes tends to enlarge.

  At this time, the tension in the direction of pulling the coupling portion 54 in the piston pin axial direction P acts on the inner wall 44, and the interval between the coupling portions 54 is prevented from increasing. Due to the tension acting on the inner wall 44, it is possible to suppress the vicinity of the skirt peripheral end portion 42 continuous with the coupling portion 54 from being elastically deformed outward in the piston radial direction R.

  As a result, the internal combustion engine 10 has a cylinder in the vicinity of the skirt peripheral end 42 and the vicinity of the skirt peripheral end 42 without making the connecting wall 50 thicker than other parts of the skirt 40. The local contact with the wall 15 can be suppressed.

  As described above, in this embodiment, the inner wall 44 that connects the connection walls 50 facing each other in the piston pin axial direction P is provided on the piston center axis C side from the skirt 40. Even if the skirt center portion 41 tries to be elastically deformed toward the piston center axis C side by the side pressure from the cylinder wall 15, tension is applied to the inner wall 44 and the vicinity of the skirt peripheral end portion 42 is deformed outward in the piston radial direction R. Can be suppressed.

  Further, in the present embodiment, the inner wall 44 extends along the piston pin axial direction P. Therefore, when the skirt peripheral end portion 42 tries to deform outward in the piston radial direction R, it is strong against this. Tension can be applied to the inner wall 44.

  In the present embodiment, the connecting portion 54 between the inner wall 44 and the connection wall 50 is assumed to extend along the piston axial direction. That is, since the coupling portion 54 extends in parallel with the piston axial direction, which is the direction in which the skirt peripheral end portion 42 is set, the elastic deformation at each portion of the skirt peripheral end portion 42 in the piston axial direction is performed. It can be uniform.

  In the present embodiment, the end 44e of the inner wall 44 on the skirt hem 40e side is set to face the skirt 40e of the skirt 40 in the piston radial direction R. That is, the inner wall 44 extends so that the distance between the end 44e of the inner wall 44 on the skirt hem 40e side and the top surface 22 is the same as the distance between the skirt 40e of the skirt 40 and the top surface 22. Thereby, the elastic deformation in the skirt peripheral end 42 can be made uniform from the top 30 side to the skirt 40e.

  The configuration of the piston and the internal combustion engine according to this embodiment will be described with reference to FIGS. 2-1 and 2-2. FIG. 2-1 is a bottom view of the piston as viewed from the skirt side. FIG. 2B is a cross-sectional view taken along line A2-A2 of FIG. In FIG. 2B, some outlines are omitted for easy understanding.

  The piston according to the present embodiment is surrounded by an inner wall and a skirt, and is formed with a guide passage capable of guiding oil flowing in from the skirt hem side to the top ceiling surface. Unlike the first embodiment, the details will be described below in that an oil jet that injects oil toward the opening on the skirt side is provided. In addition, about the structure substantially common with Example 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 2A, the piston 20 </ b> B is provided with an inner wall 44 </ b> B that joins the connection walls 50 to the piston center axis C side from the skirt 40. The inner wall 44B extends so as to face the inner peripheral surface 40c of the skirt 40. As shown in FIG. 2-2, the inner wall 44B and the inner peripheral surface 40c of the skirt 40 extend from the inner peripheral surface 30c of the top 30 to the inner wall 44B. An opening 80a (hereinafter referred to as a top side opening) is formed between the continuous connection surfaces 39. The piston 20B is formed with a passage 80 (hereinafter referred to as a guide passage) that is surrounded by the inner peripheral surface 40c of the skirt 40, the outer surface 44a of the inner wall 44B, and a part of the connection wall 50 and extends in the piston axial direction. . The guide passage 80 extends in the piston axial direction.

  The shape of the top side opening 80a of the guide passage 80 is defined by the end 44f on the top 30 side of the inner wall 44B and the connection surface 39. On the other hand, the shape of the opening 80c on the skirt hem 40e side of the guide passage 80 (hereinafter referred to as the skirt hem side opening) is defined by the skirt 40e of the skirt 40 and the end 44e of the inner wall 44B facing the skirt 40e. . The guide passage 80 in which the openings 80a and 80c are formed in this way is jetted by an oil jet, which will be described later, and causes the oil flowing in from the skirt hem side opening 80c to flow out from the top side opening 80a, and the ceiling surface of the top 30 It is possible to guide to 26.

  As shown in FIGS. 2A and 2B, the internal combustion engine 10 including the piston 20B configured as described above is provided with an oil jet 100 that injects oil toward the inside of the piston. The oil jet 100 is provided in the opening edge 12e (see FIG. 1-1) on the crank side of the cylinder bore 14 in the cylinder block 12.

  The oil jet 100 is provided with a nozzle 102 that guides oil to the inside of the piston. In the internal combustion engine 10, when the piston 20B is located closest to the crank side in the cylinder bore 14, the nozzle hole 102a of the nozzle 102 is It is configured to be positioned between the inner surface 40c of the skirt 40 and the outer surface 44a of the inner wall 44B in the radial direction R. That is, the nozzle hole 102 a of the nozzle 102 is disposed corresponding to the skirt hem side opening 80 c of the guide passage 80.

  In the internal combustion engine 10 configured as described above, the oil jet 100 is supplied with oil from an oil passage (not shown), and injects oil into the guide passage 80 from the nozzle hole 102a of the nozzle 102. The oil injected into the guide passage 80 flows toward the top 30 of the piston 20 while diffusing in the guide passage 80 as indicated by an arrow F1 in the figure.

  The oil flowing in the guide passage 80 and deflected in the flow direction toward the piston central axis C by the connection surface 39 of the top 30 is throttled between the connection surface 39 of the top 30 and the outer surface 44a of the inner wall 44B. As shown by the arrow F2 in the figure, the air flows out from the top side opening 80a of the guide passage 80 toward the ceiling surface 26. The oil flowing out from the top side opening 80 a flows along the inner peripheral surface 30 c of the top portion 30 and reaches the ceiling surface 26.

  The oil that has flowed out of the guide passage 80 and has reached the ceiling surface 26 flows along the ceiling surface 26 on the piston central axis C side as indicated by an arrow F3 in the figure. Thus, in the internal combustion engine 10 according to the present embodiment, the oil supplied from the oil jet 100 can flow along the ceiling surface 26 by the guide passage 80. Thereby, the top part 30 and the top surface 22 of the piston 20B can be efficiently cooled from the ceiling surface 26.

  As described above, in the present embodiment, the guide wall 80 that is surrounded by the inner wall 44B and the skirt 40 and can guide the oil flowing in from the skirt skirt 40e side to the ceiling surface 26 is provided. The guide passage 80 formed between the inner wall 44B and the skirt 40 flows in from the skirt skirt 40e side while suppressing the deformation of the vicinity of the skirt peripheral end 42 to the outside in the piston radial direction R due to the tension acting on 44B. It is possible to cool the top 30 of the piston 20 </ b> B by guiding the oil to the ceiling surface 26.

  The structure of the piston according to the present embodiment will be described with reference to FIGS. 3-1 and 3-2. FIG. 3A is a bottom view of the piston as viewed from the skirt side of the skirt. 3-2 is a cross-sectional view taken along line A3-A3 of FIG. 3-1. In FIG. 3-2, some outlines are omitted for easy understanding. The piston according to the present embodiment is different from the first embodiment in that it has a beam wall that joins the center portion of the skirt and the inner wall, and the details will be described below. In addition, about the structure substantially common with Example 1, 2, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 3A, the piston 20 </ b> C is provided with a beam wall 46 that connects a skirt central portion 41 that is a central portion in the circumferential direction of the skirt 40 and an inner wall 44 </ b> C. The beam wall 46 extends from the skirt central portion 41 in a direction perpendicular to the piston pin axial direction P, that is, toward the piston central axis C, and connects the skirt central portion 41 and the central portion 44g of the inner wall 44C. . That is, the beam wall 46 extends from the skirt center portion 41 in the direction in which the thrust reaction force from the cylinder wall 15 acts on the center portion.

  As shown in FIG. 3-2, the beam wall 46 extends from the connection surface 39 of the top portion 30 toward the skirt hem 40e in the piston axial direction. The distance between the end 46e of the beam wall 46 on the skirt hem 40e side and the piston top surface 22 is the distance between the skirt 40e of the skirt 40 and the piston top surface 22 and the end 44e of the inner wall 44C on the skirt skirt 40e side and the top surface of the piston. It is set to be the same as the distance to 22.

  A space between the skirt 40 and the inner wall 44C is partitioned by a beam wall 46 as shown in FIG. 3-1, and two cavities 78a and 78c are formed in the piston 20C. Each cavity is surrounded by the inner peripheral surface 40c of the skirt 40, the outer surface 44a of the inner wall 44C, and the side surface 46f of the beam wall 46, and extends in the piston axial direction.

  The piston 20 </ b> C configured in this manner receives a lateral pressure (thrust reaction force) from the cylinder wall 15, and when the skirt central portion 41 is elastically deformed toward the piston central axis C, the beam wall 46 extends from the skirt central portion 41. Stress is transmitted to the central portion 44g of the inner wall 44C. The inner wall 44 </ b> C receives the stress from the beam wall 46 and is bent and deformed (elastically deformed) toward the piston central axis C side. Tension acts on the inner wall 44C that bends and deforms so that the connecting portion 54 with the connecting wall 50 is pulled toward the piston center axis C, and the vicinity of the skirt peripheral end 42 is prevented from elastically deforming outward in the piston radial direction R. To do. At the same time, the skirt central portion 41 is restrained from being deformed toward the piston central axis C by receiving the reaction force of the inner wall 44C from the beam wall 46.

  In this manner, the piston 20C suppresses deformation of the vicinity of the skirt peripheral end portion 42 toward the outside in the piston radial direction R, and suppresses deformation of the skirt central portion 41 toward the piston central axis C side. Become. As a result, the internal combustion engine 10 is capable of elastic deformation of the skirt 40 on the piston central axis C side without making the thickness of the skirt peripheral end portion 42 of the piston 20C and the connecting wall 50 thicker than that of the skirt 40. Can be made uniform.

  As described above, in this embodiment, since the beam wall 46 that connects the skirt center portion 41 and the inner wall 44C is provided, the vicinity of the skirt peripheral end portion 42 is deformed outward in the piston radial direction R. While suppressing this, deformation of the skirt central portion 41 toward the piston central axis C can be suppressed.

  In the present embodiment, the beam wall 46 extends from the skirt central portion 41 toward the piston central axis C. Therefore, the beam wall 46 receives the stress received from the skirt central portion 41 and the central portion 44g of the inner wall 44C. Thus, the inner wall 44C is bent and deformed toward the piston central axis C, and a tension can be applied so that the coupling portion 54 between the inner wall 44C and the connection wall 50 is pulled toward the piston central axis C. Thereby, it is possible to suppress the vicinity of the skirt peripheral end portion 42 from being deformed outward in the piston radial direction R while suppressing the deformation of the skirt central portion 41 toward the piston central axis C, and the piston of the skirt 40 The elastic deformation toward the central axis C can be made uniform.

  The configuration of the piston and the internal combustion engine according to the present embodiment will be described with reference to FIGS. FIG. 4-1 is a bottom view of the piston as viewed from the skirt side. FIG. 4B is a sectional view taken along line A4-A4 in FIG. In FIG. 4B, some outlines are omitted for easy understanding. The piston according to the present embodiment is partitioned by a beam wall to form a plurality of guide passages having openings on the top side and the skirt bottom side, and the oil jet provided in the internal combustion engine is connected to the skirt bottom of the guide passage. Unlike the second embodiment, the details will be described below in that a plurality of nozzle holes are provided corresponding to the opening on the side. In addition, about the structure substantially common with Example 2, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 4A, the piston 20D is provided with three beam walls 46 that connect the skirt 40 and the inner wall 44D. The beam wall 46 extends from the inner peripheral surface 40c of the skirt 40 to the outer surface 44a of the inner wall 44D in a direction perpendicular to the piston pin axial direction P, and connects the skirt 40 and the inner wall 44D. That is, the beam wall 46 extends from the inner wall 44D in a direction orthogonal to the direction in which the inner wall 44D extends. The beam walls 46 are provided at predetermined intervals in the piston pin axial direction P.

  As shown in FIG. 4B, the inner wall 44D extends in the piston axial direction so as to face the inner peripheral surface 40c of the skirt 40, and the beam wall 46 has the same length in the piston axial direction corresponding to the inner wall 44D. It is extended. The distance between the end 44e of the beam wall 46 on the skirt hem 40e side and the piston top surface 22 is the distance between the skirt 40e of the skirt 40 and the piston top surface 22, and the end 44e of the inner wall 44D on the skirt skirt 40e side and the top surface of the piston. It is set to be the same as the distance to 22.

  As shown in FIG. 4A, the space between the skirt 40 and the inner wall 44D is partitioned by three beam walls 46 to form four guide passages (86, 88). Specifically, there are two inner guide passages 86 on the center side of the skirt 40 and two outer guide passages 88 on the skirt peripheral end portion 42 side.

  The inner guide passage 86 is surrounded by the inner peripheral surface 40c of the skirt 40, the outer surface 44a of the inner wall 44D, and the side surface 46f of the beam wall 46, and the outer guide passage 88 is the outer surface of the inner peripheral surface 40c of the skirt 40 and the inner wall 44D. 44a and a part of the connection wall 50. Each guide passage 86, 88 extends in the piston axial direction.

  As shown in FIG. 4B, between the end 44f on the top 30 side of the inner wall 44D, the connection surface 39 continuous from the inner peripheral surface 40c of the skirt 40 to the inner peripheral surface 30c of the top 30, and the inner wall 44D. A top opening 86a of the guide passage 86 is formed. That is, the shape of the top opening 86a of the guide passage 86 is defined by the end 44f on the top 30 side of the inner wall 44D and the connection surface 39. On the other hand, the shape of the skirt hem side opening 86c of the guide passage 86 is defined by the skirt 40e of the skirt 40 and the end 44e of the inner wall 44D facing the skirt hem 40e side. Thus, the guide passage 86 in which the openings 86a and 86c are formed allows the oil, which is injected from the oil jet 100B, which will be described later, and flows into the skirt skirt 40e side opening 86c to flow out from the top side opening 86a, and the ceiling of the top part 30. It is possible to guide toward the surface 26.

  Similarly to the inner guide passage 86, the outer guide passage 88 has a top side opening and a skirt hem side opening (not shown). Oil flowing in from the skirt hem side opening is allowed to flow out from the top side opening. It is possible to guide toward the ceiling surface 26 of the top 30.

  When the skirt 40 receives the lateral pressure from the cylinder wall 15 and elastically deforms the skirt 40 toward the piston central axis C, the three beam walls 46 disperse the stress from the skirt 40 and the inner wall 44D. The entire inner wall 44D is elastically deformed toward the piston central axis C side. Tension acts on the inner wall 44D so as to draw the connecting portion 54 with the connection wall 50 toward the piston center axis C, thereby preventing the vicinity of the skirt peripheral end portion 42 from being deformed outward in the piston radial direction R. At the same time, the entire skirt 40 receives a reaction force from the beam wall 46, and is prevented from being deformed toward the piston center axis C side. In this way, when the piston 20D receives stress from the cylinder wall 15, the entire skirt 40 can be deformed toward the piston central axis C, and local deformation of the skirt 40 is suppressed. Can do.

  Furthermore, in the internal combustion engine 10 provided with the piston 20D, as shown in FIGS. 4A and 4B, guide passages 86 and 88 formed between the skirt 40, the inner wall 44D, and the beam wall 46 are provided. An oil jet 100B for injecting oil is provided. The oil jet 100B includes a nozzle 102B that guides oil to the guide passages 86 and 88, and the nozzle 102B is branched into four forks and has four injection holes 102Ba. The four injection holes 102Ba are provided corresponding to the skirt skirt side openings 86c of the guide passages 86 and 88 formed in the piston 20D. Specifically, in the internal combustion engine 10, when the piston 20D is located on the most crank side in the cylinder bore 14, the four injection holes 102Ba of the nozzle 102B are disposed toward the corresponding guide passages 86 and 88, respectively. Yes.

  In the internal combustion engine 10 configured as described above, the oil jet 100B injects oil into the corresponding guide passages 86 and 88 from the four injection holes 102Ba formed in the nozzle 102B. The oil injected into the guide passages 86 and 88 flows in the guide passages 86 and 88 toward the piston top 30 as indicated by an arrow F4 in the figure. The oil flows linearly in the piston axial direction in the substantially cylindrical guide passages 86 and 88. That is, the oil is rectified in the guide passages 86 and 88. The oil flowing in the guide passages 86 and 88 and deflected in the direction of flow toward the piston central axis C by the connecting surface 39 of the top 30 is throttled between the connecting surface 39 and the outer surface 44a of the inner wall 44D. As shown by arrows F5 and F8, the gas flows out from the top opening 86a, flows along the inner peripheral surface 30c of the top 30, and reaches the ceiling surface 26.

  The oil that flows out from the inner guide passage 86 flows on the piston center axis C side of the ceiling surface 26 at right angles to the piston pin axial direction P, while it flows out from the outer guide passage 88, as indicated by an arrow F6. Flows on the inner surface 60c side of the pin boss 60 in the ceiling surface 26 perpendicular to the piston pin axial direction P, as indicated by an arrow F9. In this way, the internal combustion engine 10 is supplied from the oil jet 100B, and guides the oil received from the opening 86c on the skirt skirt 40e side of the guide passages 86, 88 to the ceiling surface 26, and between the inner surfaces 60c of the pin bosses 60 facing each other. Can flow evenly. Thereby, cooling of the top part 30 of piston 20D can be made uniform.

  As described above, in this embodiment, the beam wall 46 extends perpendicular to the piston pin axial direction P, and a plurality of beam walls 46 are provided at predetermined intervals in the piston pin axial direction P. Therefore, the stress received by the skirt 40 from the cylinder wall 15 can be dispersed and transmitted to the inner wall 44D, and the entire skirt 40 is uniformly deformed toward the piston central axis C, so that the skirt 40 is locally deformed. It is possible to suppress the occurrence. In addition, the rigidity of the skirt 40 can be improved.

  In this embodiment, the guide passages 86 and 88 are partitioned by the beam wall 46, and a plurality of guide passages 86 and 88 having openings 86a and 86c on the top 30 side and the skirt hem 40e side are formed. An oil jet 100B in which an injection hole 102Ba is disposed corresponding to the opening 86c on the skirt skirt 40e side of the guide passages 86 and 88 is provided. Even if the moving speed of the piston 20D is fast and the air flow is disturbed inside the piston, the guide passages 86 and 88 rectify the oil jetted from the oil jet 100B and guide it to the ceiling surface 26, and the ceiling between the pin bosses 60. It can flow uniformly along the surface 26. As a result, the top portion 30 of the piston 20D can be uniformly cooled.

  The configuration of the piston and the internal combustion engine according to this embodiment will be described with reference to FIGS. FIG. 5A is a bottom view of the piston as viewed from the skirt side of the skirt. FIG. 5B is a cross-sectional view taken along line A5-A5 of FIG. In FIG. 5B, some outlines are omitted for easy understanding. The piston according to the present embodiment is different from the first embodiment in that a notch is formed in a portion of the inner wall on the skirt hem side corresponding to the flange portion of the connecting rod, and the details will be described below. In addition, about the structure substantially common with Example 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 5A, a connecting rod (indicated by a two-dot chain line in the figure) is attached to the pin boss 60 of the piston 20E via a piston pin (not shown). In the internal combustion engine 10, when the piston 20E moves to the crank side or the head side in the cylinder bore 14, the connecting rod 16 is inclined with respect to the piston central axis C as shown in FIG. Sixteen flanges 16 a are close to the skirt 40. At this time, the flange portion 16a of the connecting rod 16 and the end 44e of the inner wall 44E on the skirt hem 40e side may interfere with each other. The “rod” of the connecting rod 16 is a rod-shaped portion that connects the small end and the large end of the connecting rod 16.

  Therefore, in the piston 20E according to the present embodiment, a cutout 90 is formed on the inner wall 44E on the skirt hem 40e side corresponding to the flange portion 16a of the connecting rod 16. As shown in FIG. 5A, the notch 90 is formed at the center in the piston pin axial direction P in the end 44e of the inner wall 44E on the skirt hem 40e side. Two sides of the cutout 90 are indicated by reference numeral 90a. The distance between the side surfaces 90a facing each other is set larger than the dimension L of the flange portion 16a of the connecting rod 16 in the piston pin axial direction P.

  Further, as shown in FIG. 5B, the notch 90 is formed from the end 44e on the skirt hem 40e side of the inner wall 44E with the piston axial direction facing the top 30 side. The bottom surface of the notch 90 is indicated by reference numeral 90e. The bottom surface 90e of the notch 90 is set at a position that does not interfere with the flange portion 16a of the connecting rod 16 when the connecting rod 16 is most inclined with respect to the central axis C of the piston 20E in the cylinder bore 14 of the internal combustion engine 10. .

  The inner wall 44E of the piston 20E in which such a notch 90 is formed has a substantially U shape having an open end on the skirt skirt 40e side. Although not shown, the bottom surface 90e of the notch 90 and the side surface 90a of the notch 90 may be smoothly connected so that the notch 90 has a half-moon shape.

  The piston 20 </ b> E configured as described above is tensioned so that the coupling portion 54 with the connection wall 50 is attracted to the inner wall 44 </ b> E when the skirt 40 receives a lateral pressure from the cylinder wall 15 and is elastically deformed toward the piston central axis C side. Acts to prevent the vicinity of the skirt peripheral end portion 42 from being deformed outward in the piston radial direction R. Thereby, it can suppress that the vicinity of the skirt peripheral edge part 42 contacts the cylinder wall 15 locally.

  As described above, in the internal combustion engine 10 according to this embodiment, the notch 90 is formed in the inner wall 44E on the skirt skirt 40e side corresponding to the flange portion 16a of the connecting rod 16. Therefore, it is possible to suppress deformation of the skirt peripheral end portion 42 in the piston radial direction R outside while preventing interference between the connecting rod 16 and the piston 20E.

  The configuration of the piston according to the present embodiment will be described with reference to FIG. FIG. 6 is a bottom view of the piston as seen from the bottom side of the skirt. The piston according to the present embodiment is different from the first embodiment in that the inner wall connecting the connecting walls is curved in a convex shape toward the piston central axis, and the details will be described below. In addition, about the structure substantially common with Example 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 6, the inner wall 44 </ b> F has an arcuate shape, and is a main portion of the inner wall 44 </ b> F and extends in the piston pin axial direction P, and with respect to the piston pin axial direction P. The end portion 45 is inclined and extends toward the piston central axis C side. The bow stem portion 43 and the end portion 45 of the inner wall 44F are continuous, and the end portion 45 of the inner wall 44F is coupled to the connecting wall 50 and the coupling portion 54. The bow stem 43 is provided offset to the pin boss 60 side with respect to the coupling portion 54. The bow stem 43 and the end 45 of the inner wall 44F may be smoothly curved and continuous.

  In this way, the inner wall 44F constituted by the bow stem portion 43 and the end portion 45 has a bow shape that is convex and curved toward the piston center axis C side. For this reason, the inner peripheral surface 40c of the skirt 40 and the outer surfaces (43a, 45a) of the inner wall 44F and the connection surface (not shown) of the top portion 30 connecting them are located on the inner side of the piston 20F in the piston radial direction R from the skirt 40. ), A bottomed cavity 79 is formed.

  In the piston 20F configured in this way, the distance T between the inner peripheral surface 40c of the skirt 40 and the outer surface 43a of the bow stem 43, which is the main part of the inner wall 44F, extends linearly and connects the coupling portions 54 together. Compared with the case where the inner wall 44 is provided, it is larger. That is, the cavity 79 is a space that is thicker in the piston radial direction R than when the linearly extending inner wall 44 (see FIG. 1-2) is provided.

  When the skirt 40 receives a lateral pressure from the cylinder wall 15 and the skirt central portion 41 tries to deform toward the piston central axis C, a tension acts on the inner wall 44F in the piston pin axial direction P, and the skirt peripheral end It can suppress that the part 42 and the connection wall 50 continuing to this elastically deform to the piston radial direction R outer side.

  As described above, the piston 20F according to the present embodiment is formed on the piston 20F because the inner wall 44F that joins the connection walls 50 has a curved shape that protrudes toward the piston center axis C. The cavity 79 is a space having a thickness in the piston radial direction R. For this reason, when the piston 20F is manufactured by sand mold casting, it is possible to easily manufacture a sand mold corresponding to the cavity and discharge casting sand from the cavity. A piston capable of suppressing deformation to the outside in the piston radial direction R in the vicinity of the skirt peripheral end can be realized with good productivity. Further, when the piston 20F is manufactured by die casting, the thickness of the die corresponding to the cavity 79 can be sufficiently increased, and the piston 20F can be produced without sacrificing the life of the die.

  In each of the above-described embodiments, the end of the inner wall on the skirt hem side is provided facing the skirt hem and the piston radial direction R, that is, the distance between the skirt hem end and the piston top surface is as follows. Although it is assumed that the distance between the bottom of the skirt and the top surface of the piston is the same, the geometric shape of the inner wall is not limited to this. The inner wall only needs to have a shape that connects the connecting walls along the piston axial direction. For example, the distance between the skirt hem side end of the inner wall and the piston top surface is the distance between the skirt hem and the piston top surface. It is also preferable to set a smaller value. By configuring the inner wall in this way, it is possible to realize a piston capable of preventing interference with the flange portion of the connecting rod without forming a notch in the inner wall.

  As described above, the present invention is useful for an internal combustion engine, and is particularly suitable for an internal combustion engine mounted as a prime mover in an automobile.

1 is a cross-sectional view illustrating a configuration around a piston of an internal combustion engine according to a first embodiment. It is the bottom view which looked at the piston which concerns on Example 1 from the skirt side of the skirt. It is sectional drawing by the A1-A1 line of FIGS. 1-2. It is the bottom view which looked at the piston which concerns on Example 2 from the skirt side of the skirt. It is sectional drawing by the A2-A2 line of FIGS. It is the bottom view which looked at the piston which concerns on Example 3 from the skirt side of the skirt. It is sectional drawing by the A3-A3 line of FIGS. It is the bottom view which looked at the piston which concerns on Example 4 from the skirt side of the skirt. It is sectional drawing by the A4-A4 line | wire of FIG. It is the bottom view which looked at the piston which concerns on Example 5 from the skirt side of the skirt. It is sectional drawing by the A5-A5 line | wire of FIGS. It is the bottom view which looked at the piston which concerns on Example 6 from the skirt side of the skirt. It is the bottom view which looked at the piston from the skirt side of the skirt.

Explanation of symbols

10 Internal combustion engine 12 Cylinder block 15 Cylinder wall 16 Connecting rod 14 Cylinder bore 18 Piston pin 20, 20B, 20C, 20D, 20E, 20F. 200 Piston 22 Top surface (Piston top surface)
26 ceiling 30 top (piston top)
32, 34 Compression ring groove 36 Oil ring groove 39 Connection surface 40 Skirt 41 Center part of skirt piston circumferential direction (skirt center part)
42 End of skirt piston in the circumferential direction (skirt end)
43 Bow stem 44, 44B, 44C, 44D, 44E, 44F Inner wall 45 End of inner wall 46 Beam wall 50 Connection wall 54 Coupling portion 60 Piston pin boss 60c Inner surface of piston pin boss 62 Piston pin hole 65 Pin boss rib 72, 74 Compression ring 76 Oil Ring 78, 78a, 78c, 79 Cavity 80 Guide passage 80a Top opening 80c Skirt skirt opening 86 Guide passage 86a Top opening 86c Skirt skirt opening 88 Guide passage 90 Notch 100, 100B Oil jet 102, 102B Nozzle 102a, 102Ba nozzle hole

Claims (10)

A piston wall boss used for an internal combustion engine, the piston wall having a piston pin boss, a skirt, and a connecting wall connecting the piston pin boss and the skirt are extended from the top,
On the piston center axis side from the skirt, an inner wall that connects the connecting walls facing each other in the axial direction of the piston pin is provided .
The inner wall extends along the axial direction of the piston pin,
The coupling portion between the inner wall and the connection wall extends along the piston axial direction,
The end of the inner wall on the skirt hem side is provided facing the skirt hem and the piston radial direction,
A beam wall is provided to connect the central portion of the piston in the circumferential direction of the skirt and the inner wall.
Piston characterized by that. The piston according to claim 1 , wherein
The piston is characterized in that the beam wall extends from the central portion of the skirt in the circumferential direction of the piston toward the central axis of the piston. The piston according to claim 2 ,
The beam wall extends along a direction orthogonal to the piston pin axial direction, and a plurality of the beam walls are provided at predetermined intervals in the piston pin axial direction. The piston according to any one of claims 1 to 3 ,
A piston characterized in that it is surrounded by an inner wall and a skirt, and a guide passage capable of guiding oil flowing in from the skirt skirt side to the top ceiling surface is formed. The piston according to claim 4 ,
The opening on the top side of the guide passage has a shape defined by an end on the top side of the inner wall and a connection surface connecting from the inner peripheral surface of the skirt to the inner peripheral surface of the top portion. The piston according to claim 4 or 5 ,
The guide passage is partitioned by a beam wall, and a plurality of guide passages having openings on the top side and the skirt bottom side are formed. The piston according to any one of claims 1 to 6 ,
A pin boss is one to which a connecting rod is attached via a piston pin.
A piston characterized in that a notch is formed in a portion of the inner wall on the skirt hem side corresponding to the flange portion of the connecting rod. The piston according to any one of claims 1 to 7 ,
A piston characterized in that the inner wall has an arcuate shape that is convex and curved toward the piston central axis. An internal combustion engine having the piston according to any one of claims 4 to 8 ,
An internal combustion engine comprising an oil jet that injects oil toward an opening on a skirt skirt side of a guide passage. An internal combustion engine according to claim 9 ,
The piston is partitioned by a beam wall, and a plurality of guide passages having openings on the top side and the skirt hem side are formed,
An internal combustion engine characterized in that the oil jet is provided with a plurality of injection holes corresponding to the openings on the skirt bottom side of the guide passage.

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