JP2007247818A - Crank shaft supporting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crank shaft supporting structure having improved durability and reliability by adopting a needle roller bearing whose parts are designed with their strength corresponding to load applied to a cage. <P>SOLUTION: The crank shaft supporting structure comprises a crank shaft 21, and the needle roller bearing 11 having a plurality of rollers 14 and a cage 13 for rotatably supporting the crank shaft 21. The cage 13 is formed with a plurality of cage segments 13a, 13b ranging over in the circumferential direction and including a circular ring portion and a plurality of columnar portions protruding from the end face of the ring portion to the axial direction. The columnar portions each include two first columnar portions located nearest each end face of the ring portion in the circumferential direction, two second columnar portions located adjacent to the two first columnar portion, respectively, and a third columnar portion arranged between the two second columnar portions. The circumferential width of the second columnar portion is set to be greater than the circumferential width of the other columnar portion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a support structure for a crankshaft used in an engine of an automobile or the like.

  Referring to FIG. 10, the crankshaft 101 includes a shaft portion 102, a crank arm 103, and a crank pin 104 for arranging a connecting rod between the adjacent crank arms 103. Conventionally, a sliding bearing or a rolling bearing has been adopted as a bearing for supporting the shaft portion 102 of the crankshaft 101. Sliding bearings have the advantage of a higher load capacity than rolling bearings. On the other hand, since the rolling bearing has a smaller frictional resistance during rotation than the sliding bearing, it has an advantage that it is possible to reduce the rotational torque and the amount of oil supplied to the support portion.

  However, the crank arm 103 is disposed at both ends of the shaft portion 102, and the bearing cannot be inserted in the axial direction. Therefore, for example, a roller bearing 105 as described in Japanese Patent Application Laid-Open No. 2004-232724 (Patent Document 1) may be employed as a bearing disposed in such a place.

  11 and 12, a roller bearing 105 described in the publication includes a split outer ring (not shown), a plurality of rollers 106 arranged along the inner surface of the split outer ring, and a split holding. Device 107. The roller bearing 105 having the above configuration is described as being suitable as a bearing for supporting the shaft portion 102 because the outer ring and the cage 107 can be incorporated from the radial direction of the shaft portion 102.

Moreover, the problem of the breakage | damage of the split cage 107 by the circumferential direction end surfaces of the split cage 107 contacting at the time of bearing rotation is pointed out. Therefore, according to the publication, it is described that the cage 107 is prevented from being damaged by increasing the section modulus of the column portion near the circumferential end surface of the split cage 107.
JP 2004-232724 A

  In the above publication, assuming that the load applied to the column 107a closest to the circumferential end surface of the cage 107 is the maximum, the circumferential width dimension of the column 107a closest to the circumferential end surface is set as follows. Wa is set to satisfy W> Wb> Wc, where Wb is the circumferential width dimension of the column part 107b adjacent to the column part 17a and Wc is the circumferential width dimension of the other column part 107c. Thus, the section modulus of the column portion 107a is made larger than those of the other column portions 107b and 107c.

  However, in a rotation test conducted by a bearing using a cage having the same width dimension for all the column parts, an example in which the second column part is broken from the circumferential end surface of the split cage has been reported, In the bearing that actually supports the shaft portion 102 of the crankshaft 101, it has been confirmed that the load applied to the column portion 107b is the largest.

  Accordingly, an object of the present invention is to provide a highly reliable and highly reliable crankshaft support structure by adopting a needle roller bearing in which the strength of each part is designed according to the load applied to the cage. That is.

  The crankshaft support structure according to the present invention includes a crankshaft, a plurality of rollers, and a needle roller bearing having a cage having a plurality of pockets for housing the rollers and rotatably supporting the crankshaft. The cage is formed by connecting a plurality of cage segments including an arc-shaped ring portion and a plurality of column portions protruding in the axial direction from the end surface of the ring portion in the circumferential direction. The column portion is between two first column portions that are closest to each circumferential end surface of the ring portion, two second column portions that are adjacent to the two first column portions, and between the two second column portions. 3rd pillar part arrange | positioned in this. And the circumferential direction width dimension of a 2nd pillar part is larger than the circumferential direction width dimension of another pillar part. Preferably, when the circumferential width dimension of the first pillar portion is a, the circumferential width dimension of the second pillar portion is b, and the circumferential width dimension of the third pillar portion is c, c <a ≦ b Have a relationship.

  By adopting the above configuration, the strength of the second column part to which the largest load is applied during rotation of the bearing can be increased, so that a crankshaft support structure having excellent durability and high reliability can be obtained.

  Preferably, the cage segment is formed between a first pocket formed between the first pillar part and the second pillar part and a third pillar part adjacent to the second pillar part and the second pillar part. It has a 2nd pocket and the 3rd pocket formed between the adjoining 3rd pillar parts. The central angle between the circumferential end surface of the ring portion and the first pocket is α, the central angle between the first pocket and the second pocket is β, and the third pocket adjacent to the second pocket and the second pocket If the central angle between them is γ, there is a relationship of α ≠ β, β ≠ γ, γ ≠ α.

  From the viewpoint of maintaining smooth rotation of the needle roller bearing, the roller diameters of all the needle rollers must be the same, and if all the needle rollers have the same roller diameter, the opening width of all the pockets Need to be the same. Since the cage of the needle roller bearing employed in the crankshaft support structure according to the present invention has different circumferential dimensions of the column portion, the pitch of adjacent pockets (α , Β, γ) must be unequal pitches.

  Preferably, the needle roller bearing further includes an outer ring in which an annular member is formed by cutting and a plurality of dividing lines extending in the axial direction are formed on the circumference of the annular member by natural splitting. Since the manufacturing process can be simplified by dividing the outer ring by the above method, a crankshaft support structure with reduced manufacturing costs can be obtained.

  Preferably, the cage segment is formed by subjecting SNCM or SCM to a carburizing process or a carbonitriding process. By manufacturing the cage segment by the above method, the strength of the entire cage segment can be increased. As a result, a more reliable crankshaft support structure can be obtained.

  Preferably, the crankshaft is used in a multi-cylinder engine. A crankshaft used for a multi-cylinder engine has a shaft portion sandwiched between crank arms at both ends, which increases in proportion to the number of cylinders. A higher effect can be expected by using the needle roller bearing configured as described above for such a crankshaft.

  According to the present invention, it is possible to obtain a crankshaft support structure with excellent durability and high reliability by increasing the strength of the second column portion to which the largest load is applied during bearing rotation.

  A crankshaft support structure according to an embodiment of the present invention will be described with reference to FIGS. 1 is a view showing a state before assembly of a crankshaft support structure according to an embodiment of the present invention, and FIGS. 2 to 7 are views showing components of a needle roller bearing that supports the crankshaft. 8 and 9 are views showing a state after the crankshaft support structure is assembled.

  Referring to FIG. 1, the crankshaft support structure is disposed between crankshaft 21, cylinder block 22a, bearing cap 22b, crankshaft 21, cylinder block 22a and bearing cap 22b. And a needle roller bearing 11 that is rotatably supported.

  Needle roller bearing 11 is divided into retainer segments 13a and 13b by outer ring 12 divided into outer ring members 12a and 12b by two dividing lines extending in the axial direction, and two dividing lines extending in the same axial direction as outer ring 12. And a plurality of needle rollers 14 held by the retainer 13 and disposed along the inner diameter surface of the outer ring 12.

  Such a needle roller bearing 11 has the advantage that a high load capacity and high rigidity can be obtained for a small bearing projection area because the needle roller 14 and the raceway surface are in line contact with each other. It is suitable as a bearing used for an engine or the like.

  Next, the cage segment 13a shown in FIG. 1 will be described with reference to FIGS. 2 is a diagram showing the cage segment 13a in which the needle rollers 14 are accommodated, FIG. 3 is a diagram showing the relationship in the circumferential width dimension of each column portion of the cage segment 13a, and FIG. 4 is a diagram of the cage segment 13a. It is a figure which shows the pitch of each pocket. In addition, the cage segment 13b has the same configuration as the cage segment 13a, and a description thereof will be omitted.

  Referring to FIG. 2, the cage segment 13 a includes a pair of ring portions 15 a and 15 b (generally referred to as “ring portion 15”) and an axially protruding ring portion 15 a and 15 b from the end surface of the ring portion 15. Provided in a region surrounded by a plurality of pillar portions 16 connected to each other and a pillar portion 16 adjacent to the ring portion 15 and a plurality of pockets 20 for accommodating the needle rollers 14. The ring portions 15a and 15b have an arc shape as shown in FIG. In this embodiment, since the cage 13 is divided into two cage segments 13a and 13b, it has a semicircular shape with a central angle of 180 °. Further, when assembled into the crankshaft 21, the retainer segments 13a and 13b are connected in the circumferential direction to form the annular retainer 13.

  Further, the column part 16 has a first roller stopper 17 that prevents the needle rollers 14 from dropping inward in the radial direction in the central part in the axial direction, and a needle roller 14 that falls out in the radial direction at both ends in the axial direction. A second roller stopper 18 and an inclined portion 19 that connects the first roller stopper 17 and the second roller stopper 18 to each other.

  With reference to FIG. 3, the column portion 16 provided in the cage segment 13 a includes two first column portions 16 a disposed at positions closest to the respective end surfaces in the circumferential direction of the ring portion 15, and Each of the first columnar portions 16a includes two second columnar portions 16b adjacent to each other and a plurality of third columnar portions 16c arranged between the second columnar portions 16b. It should be noted that an arbitrary number of third pillar portions 16c can be provided and have the same shape.

  Here, the circumferential width dimension of each column part 16 is the circumferential width dimension of the first pillar part 16a, the circumferential width dimension of the second pillar part 16b is b, and the circle of the third pillar part 16c. When the circumferential width dimension is c, it is set in a range satisfying c <a ≦ b. Here, the circumferential width dimension of the column portion 16 is the largest in the second roller stopper 18 and decreases in the order of the first roller stopper 17 and the inclined portion 19. Further, each of the portions 17, 18, 19 increases from the radially inner side toward the radially outer side. However, when the corresponding portions of the pillars 16a, 16b, and 16c are compared, the setting is always made to satisfy the above relationship.

  As described above, by making the circumferential width dimension of the second pillar portion 16b larger than the circumferential width dimension of the other pillar portions 16a and 16c, the second pillar to which the largest load is applied when the bearing rotates. The strength of the portion 16b can be increased. Here, it is conceivable to increase the strength of the entire cage segment 13a by setting the circumferential width dimension of all the column portions 16 to be the same as the second column portion 16b (a = b = c). Increasing the circumferential width dimension of 16 reduces the number of needle rollers 14 that can be accommodated, or the roller diameter must be reduced to maintain the number. This is not appropriate because it reduces the load capacity of the needle roller bearing 11. Therefore, it is preferable to set the circumferential width dimension according to the magnitude of the load applied to each of the pillar portions 16a, 16b, and 16c as in the above configuration.

  Referring to FIG. 4, pocket 20 provided in cage segment 13a has two first pockets 20a provided between first pillar part 16a and second pillar part 16b, and second pillar part 16b. And two second pockets 20b provided between the third pillars 16c adjacent to the second pillars 16b and a plurality of third pockets 20c provided between the adjacent third pillars 16c. Including. In this embodiment, an example is shown in which three third pillars 16c and three third pockets 20c are provided. Further, all the pockets 20a, 20b, 20c have the same shape and size, and accommodate the needle rollers 14 having the same shape and size.

  Here, since the circumferential width dimensions of the pillar portions 16a, 16b, and 16c are different from each other, and the circumferential width dimensions of the pockets 20a, 20b, and 20c are the same, the pitch of the pockets 20a, 20b, and 20c is the same. Are unequal pitches. That is, the central angle between the circumferential end face of the cage segment 13a and the first pocket 20a is α, the central angle between the first pocket 20a and the second pocket 20b is β, the second pocket 20b and the second pocket 20b. If the central angle between the third pockets 20c adjacent to γ is γ, α ≠ β, β ≠ γ, and γ ≠ α are established. This relationship also applies to the right pitch in the figure. Further, the central angle between the adjacent third pockets 20c is the same as γ.

  In this embodiment, since the circumferential width dimension of each column part 16a, 16b, 16c is c <a ≦ b, the central angle is γ <α ≦ β. In the present specification, the “center angle” refers to the rotation center O of the bearing and the circumferential end of the cage segment 13a, or the rotation center of the needle rollers 14 accommodated in the pockets 20a, 20b, 20c. The angle formed by the straight line connecting

  The cage segment 13a having the above-described configuration is formed by, for example, pressing or cutting using nickel chrome molybdenum steel (SNCM) or chrome molybdenum steel (SCM) as a starting material. Furthermore, in order to obtain a predetermined strength and other mechanical properties, carburizing or carbonitriding is performed.

  Next, the outer ring 12 shown in FIG. 1 will be described with reference to FIGS. 5 is a diagram showing a state of the outer ring 12 before the division, FIG. 6 is a diagram showing a state in which the outer ring 12 is naturally split, and FIG. 7 is an enlarged view of a divided portion of the outer ring 12.

  Referring to FIG. 5, the outer ring 12 is processed into a cylindrical annular member by cutting or the like. Further, since the inner diameter surface of the outer ring 12 functions as a raceway surface of the needle rollers 14, grinding is performed to ensure smooth rotation of the needle rollers 14.

  Referring to FIG. 6, an impact load is applied to the outer diameter surface or end surface of the annular member to form a plurality of dividing lines extending in the axial direction on the circumference of the annular member. Thereby, the outer ring members 12a and 12b are obtained. In this embodiment, the outer ring members 12a and 12b have a semicircular shape with a central angle of 180 °. Referring to FIG. 7, the end faces of the divided portions of outer ring members 12a and 12b are not subjected to grinding or the like, so that the unevenness when broken is left. When the bearing is used, a cylindrical outer ring is obtained by abutting the corresponding end faces. Such a manufacturing method is called “natural split”.

  Next, a method of incorporating the needle roller bearing 11 having the above-described configuration into the crankshaft 21 will be described with reference to FIGS.

  First, the cage segments 13a and 13b in which the needle rollers 14 are previously incorporated in the pockets are prepared. Next, the outer ring member 12a on one side is assembled into the cylinder block 22a, and the cage segment 13a on one side, the crankshaft 21, the cage segment 13b on the other side, and the outer ring member 12b on the other side are placed thereon. Finally, the bearing cap 22b is assembled, and the cylinder block 22a and the bearing cap 22b are fixed with bolts or the like.

  By adopting the above assembling procedure, the inner diameter surfaces of the crankshaft 21, the cage 13, the outer ring 12, the cylinder block 22a and the bearing cap 22b are arranged concentrically so that the needle roller 14 can be rotated stably. Can be secured. Moreover, by using the above assembling procedure, it is possible to assemble the shaft part sandwiched between the crank arms at both ends.

  In the above embodiment, the outer ring 12 has been shown as an example including two outer ring members 12a and 12b. However, the present invention is not limited to this, and three or more outer ring members may be combined. The two outer ring members 12a and 12b are semicircular with a central angle of 180 °, and the same shape is shown. However, the present invention is not limited to this, and the central angles may be different. Good. Furthermore, these can be similarly considered when the cage 13 is divided into cage segments 13a and 13b.

  In the above embodiment, the example in which the circumferential width dimensions of the first to third pillar portions 16a, 16b, and 16c are set so as to satisfy c <a ≦ b is shown. Is larger than the circumferential widths a and c of the other pillars 16a and 16b, and the circumferential width a of the first pillars 16a and the circumference of the third pillars 16c. Even if the direction width dimension c is the same, a certain effect can be expected.

  In the above-described embodiment, an example in which three third pillars 16c and three third pockets 20c are provided has been described. However, the present invention is not limited to this, and an arbitrary number can be used. The number of the third pockets 20c is determined by the circumferential width of each of the column portions 16a, 16b, 16c, the roller diameter of the needle rollers 14, and the like.

  In the above embodiment, the example of the needle roller bearing 11 provided with the outer ring 12, the cage 13, and the needle roller 14 is shown. However, the present invention is not limited to this, and the cage is omitted from the outer ring. A cage-and-roller composed of needle rollers may be used.

  Furthermore, the crankshaft support structure according to the present invention can be applied to the crankshafts of all engines such as automobiles and motorcycles. Further, the number of cylinders of the engine may be single cylinder or multi-cylinder, but it is used for a multi-cylinder engine having a shaft portion whose both ends are sandwiched by crank arms as shown in P portion of FIG. By applying to a crankshaft, a greater effect can be expected.

  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.

  The present invention is advantageously used for an engine crankshaft support structure.

It is a figure which shows the state before the assembly of the crankshaft support structure which concerns on one Embodiment of this invention. It is a figure which shows the state which accommodated the needle roller of the cage used for the needle roller bearing of FIG. It is a figure which shows the circumferential direction width dimension of each pillar part of the retainer segment used for the needle roller bearing of FIG. It is a figure which shows the pitch between each pocket of the holder | retainer segment used for the needle roller bearing of FIG. It is a figure which shows the outer ring | wheel used for the needle roller bearing of FIG. It is a figure which shows the state which divided | segmented the outer ring | wheel of FIG. 5 by natural splitting. It is an enlarged view of the division part of FIG. It is the figure which looked at the state after the assembly of the crankshaft support structure which concerns on one Embodiment of this invention from the axial direction. It is the figure which looked at the state after the assembly of the crankshaft which concerns on one Embodiment of this invention from the direction perpendicular | vertical to an axis | shaft. It is a figure which shows a crankshaft. It is a figure which shows the conventional needle roller bearing. It is a figure which shows the holder | retainer of the needle roller bearing of FIG.

Explanation of symbols

  11, 105 needle roller bearing, 12 outer ring, 12a, 12b outer ring member, 13, 107 cage, 13a, 13b cage segment, 14, 106 needle roller, 15, 15a, 15b ring part, 16, 16a, 16b , 16c, 107a, 107b, 107c Column, 17, 18 Roller stop, 19 Inclined part, 20, 20a, 20b, 20c Pocket, 21, 101 Crankshaft, 22a Cylinder block, 22b Bearing cap, 102 Shaft part, 103 Crank arm, 104 crankpin.

Claims (6)

A crankshaft,
A crankshaft support structure comprising a plurality of rollers and a needle roller bearing having a cage having a plurality of pockets for accommodating the rollers and rotatably supporting the crankshaft;
The cage is formed by connecting a plurality of cage segments including an arc-shaped ring portion and a plurality of column portions protruding in an axial direction from an end surface of the ring portion in a circumferential direction,
The column portions include two first column portions that are closest to each end surface in the circumferential direction of the ring portion, two second column portions adjacent to the two first column portions, and the two second column portions. Including a third pillar portion disposed between the pillar portions,
The crankshaft support structure, wherein a circumferential width dimension of the second pillar portion is larger than a circumferential width dimension of other pillar portions. The circumferential width dimension of the first pillar part is a, the circumferential width dimension of the second pillar part is b, and the circumferential width dimension of the third pillar part is c,
c <a ≦ b
The crankshaft support structure according to claim 1, having the relationship: The cage segment is
A first pocket formed between the first pillar part and the second pillar part;
A second pocket formed between the second pillar part and the third pillar part adjacent to the second pillar part;
A third pocket formed between the adjacent third pillar portions,
The central angle between the circumferential end surface of the ring portion and the first pocket is α, the central angle between the first pocket and the second pocket is β, and the second pocket and the second pocket are adjacent to each other. If the central angle between the third pockets is γ,
α ≠ β, β ≠ γ, γ ≠ α
The crankshaft support structure according to claim 1 or 2, which has the following relationship.   The said needle roller bearing is further provided with the outer ring | wheel which formed the annular member by cutting and formed the some division line extended in the axial direction on the circumference of the said annular member by natural splitting. The crankshaft support structure according to any one of the above. The cage segment starts with SNCM or SCM,
The crankshaft support structure according to any one of claims 1 to 4, wherein the crankshaft support structure is formed by performing a carburizing process or a carbonitriding process.   The crankshaft support structure according to any one of claims 1 to 5, wherein the crankshaft is used in a multi-cylinder engine.

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