JP2007064391A - Piston pin support structure of engine, crankshaft support structure of engine, and two-cycle engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston pin support structure of an engine with enhanced anti-seizure property. <P>SOLUTION: In the cage of a shell roller bearing fitted to the small end of a connecting rod, the center part of a column part 22 is bent by pushing to the inner diameter surface 28 side so that its cross sectional shape is formed in a V-shape. The center part of the column is positioned on the inner diameter surface 28 side more than an annular part 21. On the side wall surface 25 of the column part 22, a shearing surface 23 is positioned on the outer diameter surface 27 side, and a fracture surface 24 is formed on the inner diameter surface 28 side. In the shell outer ring contained in the shell roller bearing, when the shell outer ring is press-fitted to a reference ring having an inner diameter hole into which the shell outer ring is press-fitted, the axial straightness of the raceway surface of the shell outer ring is 0.008 mm or less, and the parallelism thereof relative to the inner diameter surface or the outer diameter surface of the reference ring is 0.015 mm or less. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine piston pin support structure, an engine crankshaft support structure, and a two-cycle engine.

  As a general-purpose engine such as a brush cutter, a two-cycle engine with a small displacement is used. A technique relating to such a two-cycle engine is described in JP-A-7-332371 (Patent Document 1).

  FIG. 12 is a longitudinal sectional view of a two-cycle engine using roller bearings at the small end and the large end of the connecting rod. Referring to FIG. 12, the two-cycle engine connects a crankshaft 83 that outputs rotational motion, a piston 85 that performs linear reciprocating motion by combustion of an air-fuel mixture, and a crankshaft 83 and piston 85, thereby reciprocating linearly. And a connecting rod 84 for converting into a rotational motion. The crankshaft 83 rotates around the rotation center shaft 90 and balances rotation by a balance weight 91.

  The air-fuel mixture obtained by mixing gasoline and lubricating oil is sent to the crank chamber 82 from the intake hole 87 and then guided to the combustion chamber 89 above the cylinder 81 and combusted in accordance with the vertical movement of the piston 85. The burned exhaust gas is discharged from the exhaust hole 88.

  The connecting rod 84 is formed by providing a large end portion 93 below the linear rod body and a small end portion 94 above. The crankshaft 83 rotates to the large end 93 of the connecting rod 84, and the piston pin 92 connecting the piston 85 and the connecting rod 84 rotates to the small end 94 of the connecting rod 84 via roller bearings 86 attached to the inner diameter holes. It is supported freely.

  The roller bearing 86 attached to the inner and outer diameter holes of the connecting rod 84 and supporting the piston pin 92 and the crankshaft 83 is subjected to a heavy load even though the bearing projected area is small. A shell-type roller bearing that can be used and has high rigidity is used. The shell-type roller bearing described above includes a shell-shaped outer ring formed by drawing a steel plate or the like, a roller, and a cage. The cage is provided with pockets for holding the rollers, and the interval between the rollers is held by a pillar portion located between the pockets.

  Here, a method for manufacturing the cage included in the above-described shell-type roller bearing will be briefly described. First, the steel strip used as the material of the cage is pocket-extracted so as to open a pocket hole having a size capable of holding the roller. Thereafter, V-shaped foam molding is performed with a molding press so that the cross-sectional shape of the steel strip is V-shaped. After forming the V-shaped foam, it is cut to the circumferential length of the cage, the cut steel sheet is bent into a cylindrical shape, the end faces of the bent steel sheets are joined together by welding, etc., and a heat treatment process is performed and held Manufacture vessel.

  When the V-shaped foam molding process is performed, a large sectional height in the radial direction can be secured, and the following effects are produced. FIG. 13 is a cross-sectional view in the radial direction before and after the cut strip steel is bent into a cylindrical shape after the V-form forming process. Before the cage 104 is bent into a cylindrical shape (FIG. 13A), the interval on the inner surface 112 side of the column portion 106 is small after the cage 104 is bent into a cylindrical shape (FIG. 13B). Therefore, it is possible to prevent the rollers 103 held in the pockets from falling to the inner diameter surface 112 side. In this case, it is also possible to prevent the roller 103 from coming out to the outer diameter surface 111 side by providing a roller drop prevention portion on the outer diameter surface 111 side of the column portion 106.

  FIG. 14 is a view showing a state in which the cage 104 holding the rollers 103 is incorporated in the shell-shaped outer ring 102 and the shaft 101, and guides the rollers 103 by performing V-shaped foam molding. However, the roller 103 can be guided in the vicinity of a PCD (Pitch Circle Diameter) 105 where the behavior is most stable.

  A roller bearing retainer having the same shape as the retainer manufactured by the above-described process is described in Japanese Patent Application Laid-Open No. 2005-98368 (Patent Document 2).

  Next, a method for measuring the accuracy of the shell type outer ring 102 included in the shell type roller bearing described above will be described. The shell-shaped outer ring 102 has a raceway surface on which the roller rolls on the inner diameter surface of the cylindrical portion. With respect to the raceway surface of the shell-shaped outer ring 102, high dimensional accuracy is required because it is necessary to roll the rollers stably.

The accuracy measurement of the raceway surface of the shell-shaped outer ring 102 that requires such a high dimensional accuracy is measuring the variation of the thickness dimension in the circumferential direction, that is, the thickness variation of the cylindrical portion of the shell-shaped outer ring 102. FIG. 15 is a diagram showing a state in which the thickness variation of the cylindrical portion of the shell-shaped outer ring 102 in this case is measured. Referring to FIG. 15, shell-shaped outer ring 102 has a raceway surface for rolling rollers on the inner surface 119 side of cylindrical portion 116 thereof. Here, regarding the measurement of the wall thickness variation of the cylindrical portion 116, the reference piece 117 is applied to the outer diameter surface 118 side of the portion indicated by the arrow X or the arrow Y in FIG. 15, and the gauge terminal is attached to the corresponding inner diameter surface 119 side. The thickness variation was measured by rotating the shell-shaped outer ring 102 in the applied state.
JP-A-7-332371 (paragraph numbers 0012 to 0013, FIG. 1) Japanese Patent Laying-Open No. 2005-98368 (paragraph number 0040, FIG. 2)

  Regarding the accuracy measurement method of the shell-shaped outer ring included in the above-described shell-type roller bearing, in measuring the thickness dimension of the cylindrical portion, the thickness variation of the cylindrical portion 116, that is, the difference in the thickness dimension in the circumferential direction is measured. Yes. However, the accuracy parameter for evaluating whether or not the roller can be rolled in a stable state is not necessarily optimal. In particular, since the cylindrical portion 116 of the shell-shaped outer ring 102 is relatively thin and may be deformed by heat treatment or the like, it is considered necessary to measure the shape after press-fitting.

  In such a case, the shape of the generatrix of the inner surface of the shell-shaped outer ring is measured with the shell-shaped outer ring being press-fitted into the inner diameter hole provided in the reference ring having a parallel reference surface, and this is used as the accuracy parameter. And However, if such a bus bar shape is used as an accuracy parameter as it is, the bus bar shape is measured including the part other than the surface on which the roller rolls, so whether or not the roller can be rolled in a stable state. It cannot be evaluated accurately.

  On the other hand, in the manufacturing method of the cage included in the shell-type roller bearing described above, in the pocket punching process, the cutting edge is pressed against the strip steel, which is the material of the cage, with a punch or the like having a punching blade. This is done by punching. In this case, a shear surface and a fracture surface are generated on the side wall surface of the punched pocket, that is, the side wall surface of the column portion located between the pockets. The shear surface is a smooth surface that is punched and cut by a cutting edge of a punching blade such as a punch. The fracture surface is a rough surface that is cut so as to be torn off by the material pushed by the blade edge when punched by a punching blade such as a punch.

  Here, in the pocket punching step, when the pocket is punched from the side that becomes the inner diameter surface when bent into a cylindrical shape, the fracture surface is located on the side that becomes the outer diameter surface of the side wall surface of the column portion.

  FIG. 16 is a sectional view in the radial direction of the cage 104 in this case. Referring to FIG. 16, when pocket removal is performed from the direction of arrow Z in FIG. 16, which is on the inner diameter surface 112 side, the cage 104 is processed into a V-shaped foam. The fracture surface 109 is located near the PCD 105 in the center of the wall surface 110. If it does so, a roller cannot be guided stably.

  In order to deal with such a problem, it is conceivable that the pocket is punched from the side that becomes the outer diameter surface 111 when bent into a cylindrical shape in the pocket removing process. As a result, the shear surface 108 is located on the side of the side wall surface 110 of the column portion 106 that becomes the outer diameter surface 111.

  A shape measurement line 114 obtained by scanning in the longitudinal direction of the side wall surface 110 on the PCD 105 in this case is shown in FIG. In FIG. 17, 1 mm in the vertical direction is 10 μm, and 1 mm in the horizontal direction is 0.2 mm. Referring to FIG. 17, the shape measurement line 114 has a shape in which an end portion that is a fracture surface is recessed with respect to a central portion that is a shear surface. If it does so, a roller will contact and guide the shear surface of the center part of a side wall surface.

  However, the portion 115 corresponding to the bent portion of the column portion of the central shear surface is convex toward the outer contour 113 of the roller with respect to the central shear surface. This is because, in the V-shaped foam molding process, when the column part was bent into a V shape, the side wall surface of the portion corresponding to the bent part of the column part was raised due to the surplus on the outer diameter side of the column part. Is due to.

  If such a convex part is included in the shearing surface that guides the roller, the entire shearing surface of the central part does not come into contact with the rolling surface of the roller when the roller is guided, and the convex part is localized. Will abut.

  A shell-type roller bearing including such a cage and a shell-type outer ring cannot stably roll the rollers. Further, when such a shell-type roller bearing is used for an engine piston pin support structure or the like, roller skew may occur and seizure may occur.

  An object of the present invention is to provide an engine piston pin support structure, an engine crankshaft support structure, and a two-cycle engine with improved seizure resistance.

  The piston pin support structure for an engine according to the present invention converts a linear reciprocating motion into a rotational motion, a connecting rod having an inner diameter hole at a small end, a piston pin connecting the connecting rod and the piston via the inner diameter hole, and an inner diameter hole And a shell-type roller bearing that is press-fitted to the piston and supports the piston pin. The above-described shell-type roller bearing includes a shell-type outer ring, a plurality of rollers, and a cage that holds the plurality of rollers. When the shell type outer ring is press-fitted into a reference ring having an inner diameter hole for press-fitting the shell type outer ring, the straightness in the axial direction of the raceway surface of the shell type outer ring is 0.008 mm or less, and the inner diameter of the reference ring The parallelism based on the surface or the outer diameter surface is 0.015 mm or less. Further, the retainer described above includes a pair of annular portions and a column portion that connects the pair of annular portions so as to form a pocket that accommodates the rollers, and bends the central portion to form a shape recessed radially inward. including. The side wall surface of the column part is located on the radially outer side and has a shearing surface punched by a punching blade so as to form a pocket, and a fracture surface that is located on the radially inner side and is torn off by a material pushed by the punching blade. . Here, among the shear surfaces, the guide surface along the rolling surface of the roller has a flat shape line that does not have a local uneven portion in a shape measurement line obtained by scanning in the longitudinal direction.

  With this configuration, the cage included in the shell-type roller bearing has no portion that locally contacts the roller on the shearing surface that guides the roller. Accordingly, the entire shear surface at the central portion comes into contact with the roller. Also, for the shell type outer ring included in the shell type roller bearing, the raceway surface on which the roller rolls is regulated straight and parallel in a state where it is press-fitted into the inner diameter hole provided in the small end portion of the connecting rod. be able to. If it does so, at the time of rolling, the rolling surface of a roller and the track surface located in the internal diameter surface of a shell type outer ring | wheel can contact appropriately.

  A shell type roller bearing including such a cage and a shell type outer ring can stably roll the roller. Therefore, the piston pin support structure of an engine provided with such a shell-type roller bearing can improve seizure resistance. Here, straightness refers to the difference between the maximum axial thickness and the minimum axial thickness of the raceway surface of the shell-shaped outer ring when the reference ring is press-fitted. Parallelism refers to the inner diameter surface of the reference ring serving as the reference surface and the shell shape. The degree of parallelism with the raceway of the outer ring. If the coaxiality between the inner diameter surface and the outer diameter surface of the reference ring is ensured, the outer diameter surface of the reference ring can be used as a reference surface for parallelism.

  Preferably, the axial length of the shear surface for guiding the roller is 60% or more of the axial length of the roller. By doing so, the cage included in the shell-type roller bearing can secure a sufficient guide surface for stably guiding the roller, and can roll the roller more stably.

  In another aspect of the present invention, the crankshaft support structure of an engine converts a linear reciprocating motion into a rotational motion, and is connected to a connecting rod having an inner diameter hole at a large end portion and a large end portion of the connecting rod through an inner diameter hole. A crankshaft that outputs rotational motion, and a shell-type roller bearing that is press-fitted into the bore and supports the crankshaft. The above-described shell-type roller bearing includes a shell-type outer ring, a plurality of rollers, and a cage that holds the plurality of rollers. When the shell type outer ring is press-fitted into a reference ring having an inner diameter hole for press-fitting the shell type outer ring, the straightness in the axial direction of the raceway surface of the shell type outer ring is 0.008 mm or less, and the inner diameter of the reference ring The parallelism based on the surface or the outer diameter surface is 0.015 mm or less. Further, the cage includes a pair of annular portions and a column portion that connects the pair of annular portions so as to form a pocket that accommodates the rollers, and bends the central portion to form a shape recessed inward in the radial direction. . The side wall surface of the column portion is located on the radially outer side and has a shearing surface punched by a punching blade so as to form a pocket, and a fracture surface that is located on the radially inner side and is torn off by a material pushed by the punching blade. . Here, among the shear surfaces, the guide surface along the rolling surface of the roller has a flat shape line that does not have a local uneven portion in a shape measurement line obtained by scanning in the longitudinal direction.

  By comprising in this way, like the above, about the holder | retainer contained in a shell type roller bearing, it will contact | abut with a roller in the whole shearing surface of a center part. Also, for the shell type outer ring included in the shell type roller bearing, the raceway surface on which the roller rolls is regulated straight and parallel in a state where it is press-fitted into the inner diameter hole provided at the large end of the connecting rod. be able to. If it does so, at the time of rolling, the rolling surface of a roller and the track surface located in the internal diameter surface of a shell type outer ring | wheel can contact appropriately.

  A shell type roller bearing including such a cage and a shell type outer ring can stably roll the roller. Therefore, the engine crankshaft support structure provided with such a shell-type roller bearing can improve seizure resistance.

  Preferably, the axial length of the shear surface for guiding the roller is 60% or more of the axial length of the roller. By doing so, the cage included in the shell-type roller bearing can secure a sufficient guide surface for stably guiding the roller, and can roll the roller more stably.

  In still another aspect of the present invention, a two-cycle engine includes any one of the above-described piston pin support structure of the engine or any of the above-described crank shaft support structures of the engine.

  By configuring in this way, a two-cycle engine with improved seizure resistance can be obtained.

  According to the present invention, in the cage included in the shell-type roller bearing, there is no portion that locally contacts the roller on the shear surface that guides the roller. Accordingly, the entire shear surface at the central portion comes into contact with the roller. Also, for the shell type outer ring included in the shell type roller bearing, the raceway surface on which the roller rolls is regulated straight and parallel in a state where it is press-fitted into the inner diameter hole provided in the small end portion of the connecting rod. be able to. If it does so, at the time of rolling, the rolling surface of a roller and the track surface located in the internal diameter surface of a shell type outer ring | wheel can contact appropriately.

  A shell type roller bearing including such a cage and a shell type outer ring can stably roll the roller. Therefore, the piston pin support structure of an engine provided with such a shell-type roller bearing can improve seizure resistance. Similarly, an engine crankshaft support structure including such a shell-type roller bearing can also improve seizure resistance.

  Further, by providing such an engine piston pin support structure or an engine crankshaft support structure, a two-cycle engine with improved seizure resistance can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a cross-sectional view showing a main part of the two-cycle engine according to one embodiment of the present invention. Referring to FIG. 2, a two-cycle engine 10 connects a piston (not shown) that performs a linear reciprocating motion by combustion of an air-fuel mixture, a crankshaft 20 that outputs a rotational motion, and a piston and the crankshaft 20. And a connecting rod 15 for converting linear reciprocating motion into rotational motion. The piston is connected to the small end portion 16 of the connecting rod 15 through the shell roller bearing 11 by a piston pin 19. Further, the crankshaft 20 is connected to the large end portion 17 of the connecting rod 15 via a shell-type roller bearing 18.

  The shell-type roller bearing 11 that supports the piston pin 19 is press-fitted into an inner diameter hole provided in the small end portion 16 of the connecting rod 15 to form a piston pin support structure of the two-cycle engine 10. Similarly, the shell-type roller bearing 18 that supports the crankshaft 20 is press-fitted into an inner diameter hole provided in the large end portion 17 of the connecting rod 15 to form a crankshaft support structure of the two-cycle engine 10. Although the shell-type roller bearings 11 and 18 press-fitted into the small end portion 16 and the large end portion 17 of the connecting rod 15 have the same configuration although having different sizes, the shell-type roller bearing 11 will be described below.

  The shell-type roller bearing 11 holds a shell-shaped outer ring 12 whose flanges at both ends are bent radially inward, a plurality of rollers 13 arranged along the inner diameter surface of the shell-shaped outer ring 12, and the rollers 13. And retainer 14. The retainer 14 connects the pair of annular portions positioned on both end surfaces of the shell-shaped outer ring 12 and the pair of annular portions so as to form a pocket for accommodating each roller, and bends the central portion thereof to radially inward. And a pillar portion having a concave shape.

  Here, a manufacturing method of the cage 14 included in the shell roller bearing 11 will be described.

  FIG. 3 is a flowchart showing a process of manufacturing the cage 14 included in the shell roller bearing 11. FIG. 4 is a schematic view showing a typical process among the processes shown in FIG. With reference to FIG. 3 and FIG. 4, the manufacturing method of the holder | retainer 14 is demonstrated.

  First, a V-form forming process (FIG. 3A) in which the steel sheet used as the material of the cage 14 is press-molded so that the cross-sectional shape is V-shaped in the state of the steel strip (FIG. 4A). 4 (b)). Here, the V-shape means that when bent into a cylindrical shape, the center portion of the steel strip and the end portion of the steel strip are pushed and bent so that a step is provided in the radial direction. This is performed by pressing with a press from the outer diameter side toward the inner diameter surface when bent into a cylindrical shape in a subsequent bending step.

  Next, a pocket punching process (FIGS. 3B and 4C) for forming a pocket for holding the roller 13 is performed on the steel strip pressed and bent by the V-form forming process. The pocket punching step is performed by punching the band steel against the band steel by pressing the blade tip into a pocket shape with a punch having a punching blade. Here, the punching direction is punched from the side that becomes the outer diameter surface when the punch is bent into a cylindrical shape in a subsequent bending step. Therefore, among the pillar portions located between the pockets formed by the pocket punching step, the center portion has a shape recessed inward in the radial direction from the annular portion located at the end portion of the steel strip.

  By doing so, in the finally manufactured cage, the side wall surface of the column portion on the outer diameter surface side becomes a shear surface, and the side wall surface of the column portion on the inner diameter surface side becomes a fracture surface. In addition, since the pocket removing process is performed after the V-shaped foam molding process is performed, the side wall surface of the column portion folded in the V-shaped foam molding process does not cause uneven thickness due to the bending. Therefore, the shearing surface of the side wall surface generated by the pocket punching process does not include a convex portion at the bent portion of the column portion.

  Then, the cutting process (FIG. 3 (C)) which cut | disconnects a strip steel is performed so that it may become the circumference length of the holder | retainer 14. FIG. Next, a bending process (FIGS. 3 (D) and 4 (d)) is performed by bending the cut steel plate into a cylindrical shape along the inner diameter surface of the shell-shaped outer ring 12, and then both end surfaces are welded or the like. After performing the joining process (FIG. 3 (E)) to join, heat treatment processes (FIG. 3 (F)) such as soft nitriding and carburizing and quenching are performed to manufacture the cage 14 (FIG. 4 ( e)).

  A plurality of rollers 13 are incorporated in the pockets of the cage 14 manufactured in this way, and the cage 14 in which the rollers 13 are incorporated is defined to have a straight and parallel raceway surface in a measurement method described later. The shell-shaped outer ring 12 is incorporated into the shell-shaped roller bearing 11.

  FIG. 1 is a sectional view in the axial direction of the cage 14 manufactured in the manufacturing process described above. In FIG. 1, a portion indicated by a dotted line indicates the roller 13 held in the pocket of the cage 14, and a one-dot chain line indicates the PCD 26. Moreover, the shape measurement line 32 obtained by scanning in the longitudinal direction of the side wall surface 25 in the PCD 26 in this case is shown in FIG. In FIG. 5, 1 mm in the vertical direction is 10 μm, and 1 mm in the horizontal direction is 0.2 mm.

  Referring to FIGS. 1 and 5, the central portion of the column portion 22 is pushed and bent toward the inner surface 28 so that the cross-sectional shape is V-shaped in the V-form forming process described above. It is located closer to the inner diameter surface 28 than the portion 21. Further, in the pocket punching process described above, since the punching blade of the punch is pressed from the outer diameter surface 27 side and punched out, the shear surface 23 is located on the outer diameter surface 27 side in the side wall surface 25 of the column portion 22. The fracture surface 24 is located on the inner surface 28 side.

  Therefore, on the PCD 26, the shear surface 23 on the outer diameter surface 27 side is located at the center of the side wall surface 25, and the fracture surface 24 on the inner diameter surface 28 side is located at the end of the side wall surface 25. Become.

  Here, the shape measurement line 32 of the portion corresponding to the bent portion of the column portion 22 does not have a local uneven portion, the shear surface 23 located at the center portion of the side wall surface 25 is flat, and the roller 13 It becomes a shape along the outer contour line 31. If it does so, the shearing surface 23 of the center part of the roller 13 and the center part of the side wall surface 25 can contact | abut with the roller 13 in the whole shearing surface 23, without contacting the roller 13 locally.

  In this case, the axial length of the shearing surface 23 guiding the roller 13 is secured 60% or more of the axial length of the roller 13. In order to set the length of the shearing surface 23 to 60% or more of the roller length, the length of the shearing surface 23 on the PCD 26 is set to 60% or more of the roller length in the V-form forming process described above. You may carry out by pushing and bending. Specifically, the dimension A in FIG. 1, that is, the dimension of the fracture surface 24 on the one annular portion 21 side of the PCD 26 is 20% or less of the dimension B, which is the axial length of the pocket. In addition, it is performed by bending in a V shape and in the radial direction. If it does in this way, the shear surface 23 which contacts the roller 13 on a flat surface can be increased, and the behavior of the roller 13 can be suppressed.

  Next, a method for measuring the straightness and parallelism of the raceway surface of the shell type outer ring will be described. First, an apparatus for measuring the straightness and parallelism of the raceway will be described. FIG. 6 is a schematic diagram of a shape measuring device 41 that measures the straightness and parallelism of the shell-shaped outer ring. Referring to FIG. 6, shell-shaped outer ring shape measuring device 41 includes reference ring 42 having inner diameter hole 45, inner diameter surface of shell-shaped outer ring press-fitted into inner diameter hole 45, and outer diameter surface 49 of reference ring 42 or A probe unit 43 that measures the generatrix shape of the inner diameter surface 46 in the axial direction, and a probe moving unit 44 that moves the probe unit 43 while scanning in the axial direction.

  The reference ring 42 has a cylindrical shape and has an inner diameter hole 45 into which a shell-shaped outer ring can be press-fitted. In addition, the inner diameter surface 46 of the inner diameter hole 45 and the outer diameter surface 49 of the reference ring 42 are ensured to be coaxial, and both surfaces are used for measuring parallelism with the raceway surface of the shell-shaped outer ring to be press-fitted. It becomes the reference plane at.

  The probe unit 43 includes a tip part 47 that measures the shape of the bus bar of the measurement object by contact with the measurement object, and an arm part 48 that connects the tip part 47 and the probe moving means 44.

  The probe moving means 44 is a moving means for scanning the probe portion 43 on the inner diameter surface of the shell-shaped outer ring press-fitted into the reference ring 42, and a movement for scanning the probe portion 43 on the outer diameter surface 49 or the inner diameter surface 46 of the reference ring 42. Means. The probe unit 43 can be moved by the probe moving means in the axial direction, that is, in the left-right direction in FIG. 6, but can also move in the up-down direction in FIG. That is, even if the measurement object is tilted, movement in the left-right direction is not restricted, and the probe unit 43 can move along the shape of the measurement object.

  Next, a measurement method for measuring the straightness and parallelism of the raceway surface of the shell-shaped outer ring using the shape measuring device 41 described above will be described. Here, as the shell-type outer ring for measuring the straightness and the like, a shell-type outer ring in a state where the flange portion at one end is bent inward in the radial direction is used, but the shell-type outer ring included in the shell-type roller bearing 11 described above is used. The same applies to the case of measuring a shell-shaped outer ring in which the flanges at both ends are bent radially inward like the outer ring 12.

  First, the shell-shaped outer ring is press-fitted into the inner diameter hole 45 of the reference ring 42. FIG. 7 is a cross-sectional view in the axial direction showing a state in which the shell-shaped outer ring 36 having a bent end at one end is press-fitted into the inner diameter hole 45 of the reference ring 42 provided in the shape measuring device 41 described above. Referring to FIG. 7, shell-shaped outer ring 36 is press-fitted so that outer diameter surface 37 of shell-shaped outer ring 36 and inner diameter surface 46 of inner diameter hole 45 are brought into contact with each other.

  Next, the bus bar shape of the outer diameter surface 49 of the reference ring 42 is measured. FIG. 8 is a cross-sectional view of the reference ring 42 in the axial direction when the generatrix shape of the outer diameter surface 49 is measured. Referring to FIG. 8, first, the reference ring 42 is tilted at a certain angle. By doing so, it becomes possible to measure the shape of the generatrix of the inner diameter side surface of the flange portion 40 of the shell-shaped outer ring 36 and the inner diameter surface 38 of the cylindrical portion.

  Thereafter, the tip portion 47 is brought into contact with the outer diameter surface 49 of the reference ring 42 and the probe portion 43 is moved in the direction of arrow C. In this way, the bus bar shape of the outer diameter surface 49 which is the reference surface of the reference ring 42 is measured. In this case, the shape of the generatrix of the inner diameter surface 46 of the inner diameter hole 45 that is the reference surface may be measured. For example, the shape of the generatrix of the inner surface 46 of the portion indicated by D in FIG. 8 is measured. By doing so, even if the bus bar shape of the outer diameter surface 49 cannot be measured, it can be used as a reference plane for measuring parallelism by measuring the bus bar shape of the inner diameter surface 46.

  Next, the bus bar shape of the inner diameter surface 38 of the shell-shaped outer ring 36 that has been press-fitted is measured. FIG. 9 is a cross-sectional view in the axial direction of the reference ring 42 when measuring the generatrix shape of the inner diameter surface 38 of the shell-shaped outer ring 36. In FIG. 9, a portion indicated by a dotted line represents the roller 35 incorporated in the shell-shaped outer ring 36. Referring to FIG. 9, the tip portion 47 is brought into contact with the inner diameter surface of the flange portion 40 of the shell-shaped outer ring 36 while the reference ring 42 into which the shell-shaped outer ring 36 is press-fitted is inclined at a certain angle. By doing so, the corner portion P on the inner diameter side of the flange portion 40 can be set as a starting point for measuring the axial shape of the generatrix. Further, since the reference ring 42 is inclined at a certain angle, even if the tip portion 47 and the arm portion 48 are vertically connected as shown in the figure, the folding is a portion where the flange portion 40 and the inner diameter surface 38 intersect. It can be easily brought into contact with the surface near the bent portion 39.

  Thereafter, the shape of the generatrix of the inner diameter surface 38 of the shell-shaped outer ring 36 is measured by moving the tip portion 47 in the direction of arrow C. With respect to the bus bar shape of the inner diameter surface 38, since the bus bar shape is measured from the inner diameter surface of the flange portion 40 toward the opening end of the shell-shaped outer ring 36, the roller 35 is moved to the measured bus bar shape of the inner diameter surface 38. When moved, it includes a portion where the roller 35 and the shell-shaped outer ring 36 do not contact each other.

  Here, of the inner diameter surface 38 of the shell-shaped outer ring 36, the straightness and the parallelism are measured in a range L2 in FIG. 9 as a range for measuring the straightness and the parallelism of the raceway surface on which the roller 35 rolls. . L2 is a range where L2 ≧ 0.8 × L when the roller length is L, and the straightness and parallelism measured by defining a range equal to or greater than a predetermined length as L2. Can be made reliable. If the dimension in the axial direction from the corner P on the inner diameter side of the flange 40 to the starting point of L2 is L1, the range is 0.8 mm ≦ L1 ≦ 2 mm. This region L1 usually corresponds to a portion where the roller 35 and the shell-shaped outer ring 36 do not contact each other.

  FIG. 10 is a cross-sectional view when the reference ring 42 into which the shell-shaped outer ring 36 is press-fitted is cut along a radial cross section. Referring to FIG. 10, as indicated by arrows E, F, G, and H, the shape of the generatrix of inner diameter surface 38 is measured in four directions that are symmetrical in the vertical and horizontal directions in FIG. By doing so, the straightness and the parallelism can be measured with improved accuracy. If further accuracy is required, the measurement may be performed in the above four directions.

  FIG. 11 is a schematic view showing the bus shape measured in this way. Referring to FIG. 11, the horizontal axis represents the dimension in the axial direction, and the vertical axis represents the measured busbar shape irregularities. With reference to the bus bar shape 51 of the outer diameter surface 49 of the reference ring 42 as the reference surface, the straight line shape and the parallelism are determined from the bus bar shape 53 in the L2 range on the inner diameter surface 38 except for the bus bar shape 52 in the L1 range. Measure the degree. That is, the straightness is the difference between the maximum value and the minimum value of the bus shape 53, and the parallelism is the degree of parallelism between the bus shape 51 and the bus shape 53. In this way, the raceway surface on which the roller rolls is defined to be straight and parallel.

  A test for confirming seizure resistance was carried out on the shell-type roller bearings including the shell-type outer rings having different values of straightness and parallelism measured in this way. For the shape measurement, a contour shape measuring machine (Mitutoyo Co., Ltd .: CV3000) was used.

  The test conditions are as follows. The test results are shown in Table 1.

Test machine: 2 cycle engine Mixing ratio: Gasoline / lubricant = 100/1
Operation pattern: Full throttle Operation time: 2 hours or until seizure

  Referring to Table 1, in the conventional product 1, seizure occurred on 3 of 10 shell roller bearings. In the conventional product 2, seizure occurred on four of the ten shell roller bearings. In the conventional product 3, seizure occurred on 7 of 10 shell roller bearings. On the other hand, in Example 1, there was no shell type roller bearing in which seizure occurred in 10 shell type roller bearings.

  Therefore, by setting the parallelism to 0.010 mm or less and the straightness to 0.008 mm or less, it is possible to stably roll the rollers and prevent seizure.

  Further, as Example 2, a shell-type roller bearing including a cage whose shearing surface is 60% or more of the roller length shown in FIG. 1, as sample A, the shearing surface is 50% of the roller length. As a shell-type roller bearing including a cage, and a conventional product 4, a shell-type roller bearing including a conventional cage was subjected to a test for confirming seizure resistance.

  The test conditions are the same as above. The test results are shown in Table 2.

  Referring to Table 2, in the conventional product 4, seizure occurred on 7 of 10 shell roller bearings. In sample A, seizure occurred on 5 of 10 shell roller bearings. In Example 2, none of the ten shell roller bearings had seizure. Therefore, it is sufficient that the axial length of the shear plane is 60%.

  As described above, the engine piston pin support structure and the engine crankshaft support structure including such a cage and the shell-type roller bearing including the shell-shaped outer ring can improve the seizure resistance. Also, seizure resistance can be improved for a two-cycle engine including such an engine piston pin support structure or engine crankshaft support structure.

  In the above embodiment, when measuring the straightness and parallelism of the raceway surface of the shell-shaped outer ring, the whole reference ring is tilted and measured. The structure may be changed to an oblique shape so that the tip of the probe portion can be brought into contact with the corner portion on the inner diameter side of the collar portion without tilting the reference ring.

  In addition, we decided to measure the generatrix shape of the outer diameter surface of the reference ring and the inner diameter surface of the shell type outer ring by bringing the tip of the probe part into contact. You may decide to measure bus-line shapes, such as the outer surface of a ring.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  Engine piston pin support structure, engine crankshaft support structure, and two-cycle engine according to the present invention include a shell-type roller bearing that can stably roll a roller, and therefore an engine with improved seizure resistance. Piston pin support structure, engine crankshaft support structure, and two-cycle engine.

2 is a sectional view in the axial direction of a cage 14 included in a shell-type roller bearing 11. FIG. 1 is a cross-sectional view showing a main part of a two-cycle engine 10 according to an embodiment of the present invention. 4 is a flowchart showing a manufacturing process of the cage 14 included in the shell roller bearing 11. It is the schematic which shows a typical process among the manufacturing processes of the holder | retainer 14, a state (a) of a steel strip, a V-shaped foam formation process (b), a pocket punching process (c), a bending process (d), The final product (e) is shown. It is a figure which shows the shape measurement line 32 of the side wall surface 25 in PCD26 on the outer contour line 31 of the roller 13 in an overlapping manner. It is the schematic of the shape measuring apparatus 41 which measures the straightness and parallelism of a shell type outer ring | wheel. FIG. 5 is an axial sectional view showing a state in which a shell-shaped outer ring is press-fitted into an inner diameter hole 45 of a reference ring. FIG. 6 is a cross-sectional view in the axial direction of the reference ring when measuring the generatrix shape of the outer diameter surface 49 of the reference ring. FIG. 5 is a cross-sectional view in the axial direction of a reference ring when measuring the shape of a generatrix of an inner diameter surface of a shell-shaped outer ring. It is sectional drawing at the time of cut | disconnecting the reference | standard ring 42 in which the shell-shaped outer ring | wheel 36 was press-fit in the cross section of radial direction. FIG. 6 is a diagram of measurement of the bus bar shape of the inner diameter surface 38 of the shell-shaped outer ring 36 and the outer diameter surface 49 of the reference ring 42. It is a longitudinal cross-sectional view of the two-cycle engine which uses the shell type roller bearing for the big end part and small end part of a connecting rod. It is sectional drawing of the radial direction which shows the state before (a) and after bending (b) before bending a strip steel. It is the figure which showed the state which hold | maintained the roller 103 in the pocket of the holder | retainer 104 which performed V-shaped foam shaping | molding process. It is a figure which shows the state which measures the thickness dimension of the cylindrical part 116 of the shell-shaped outer ring | wheel 102 in the past. It is sectional drawing of the radial direction of the holder | retainer 104 when the shearing surface 108 is located in the inner diameter surface 112 side, and the fracture surface 109 is located in the outer diameter surface 111 side. The figure which shows the shape measurement line 114 of the side wall surface 110 in the PCD 105 when the shearing surface 108 is positioned on the outer diameter surface 111 side and the fracture surface 109 is positioned on the inner diameter surface 112 side, and the outer contour line 113 of the roller 103. It is.

Explanation of symbols

10 2-cycle engine, 11, 18 Shell type roller bearing, 12, 36 Shell type outer ring, 13, 35 roller, 14 Cage, 15 Connecting rod, 16 Small end, 17 Large end, 19 Piston pin, 20 Crankshaft, 21 annular part, 22 column part, 23 shear surface, 24 fracture surface, 25 side wall surface, 26 PCD, 27, 37, 49 outer diameter surface, 28, 38, 46 inner diameter surface, 31 outer contour line, 32 shape measurement line, 39 bending part, 40 collar part, 41 shape measuring device, 42 reference ring, 43 probe part, 44 probe moving means, 45 inner diameter hole, 47 tip part, 48 arm part, 51, 52, 53 bus bar shape.

Claims (5)

A connecting rod that converts linear reciprocating motion into rotational motion and has an inner diameter hole at the small end,
A piston pin connecting the connecting rod and the piston through the inner diameter hole;
In a piston pin support structure of an engine comprising a shell-type roller bearing press-fitted into the inner diameter hole and supporting the piston pin,
The shell-type roller bearing includes a shell-type outer ring, a plurality of rollers, and a cage that holds the plurality of rollers.
When the shell-shaped outer ring is press-fitted into a reference ring having an inner diameter hole for press-fitting the shell-shaped outer ring, the axial straightness of the raceway surface of the shell-shaped outer ring is 0.008 mm or less, and the reference ring The parallelism based on the inner diameter surface or the outer diameter surface is 0.015 mm or less,
The retainer includes a pair of annular portions and a column portion that connects the pair of annular portions so as to form a pocket that accommodates the roller, and is bent at the center to be recessed radially inward. Including
A side wall surface of the pillar portion is located on the radially outer side, a shear surface punched by a punching blade so as to form the pocket, and a fracture surface that is located on the radially inner side and is torn by a material pushed by the punching blade. Have
The piston pin of the engine in which the guide surface along the rolling surface of the roller among the shear surfaces has a flat shape line having no local uneven portions in a shape measurement line obtained by scanning in the longitudinal direction. Support structure. 2. The piston pin support structure for an engine according to claim 1, wherein an axial length of the shearing surface that guides the roller is 60% or more of an axial length of the roller. 3. A connecting rod that converts linear reciprocating motion into rotational motion and has an inner diameter hole at the large end,
A crankshaft connected to the large end of the connecting rod via the inner diameter hole and outputting rotational motion;
In a crankshaft support structure for an engine comprising a shell-type roller bearing press-fitted into the inner diameter hole and supporting the crankshaft,
The shell-type roller bearing includes a shell-type outer ring, a plurality of rollers, and a cage that holds the plurality of rollers.
When the shell-shaped outer ring is press-fitted into a reference ring having an inner diameter hole for press-fitting the shell-shaped outer ring, the axial straightness of the raceway surface of the shell-shaped outer ring is 0.008 mm or less, and the reference ring The parallelism based on the inner diameter surface or the outer diameter surface is 0.015 mm or less,
The retainer includes a pair of annular portions and a column portion that connects the pair of annular portions so as to form a pocket that accommodates the roller, and is bent at the center to be recessed radially inward. Including
A side wall surface of the pillar portion is located on the radially outer side, a shear surface punched by a punching blade so as to form the pocket, and a fracture surface that is located on the radially inner side and is torn by a material pushed by the punching blade. Have
Among the shear surfaces, the guide surface along the rolling surface of the roller has a flat shape line that does not have local uneven portions in a shape measurement line obtained by scanning in the longitudinal direction. Support structure. The crankshaft support structure for an engine according to claim 3, wherein an axial length of the shearing surface for guiding the roller is 60% or more of an axial length of the roller. A two-cycle engine comprising the engine piston pin support structure according to claim 1 or 2, or the engine crankshaft support structure according to claim 3 or 4.

Images