JP2009014014A - Roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roller bearing capable of reducing friction. <P>SOLUTION: A roller bearing comprises rolling elements 3 rollable along an annular bearing ring 2, having the specific gravity of a weight part 32 as an outer peripheral structure is set higher than the specific gravity of a rolling element main body 31. That is, the rolling body 3 has the rolling element main body 31 formed solidly to form an inside structure, and the weight part 32 to form the outer peripheral structure provide in the outer periphery of the rolling body main body 31, having a gravity set higher than the rolling element main body 31. Thereby, rotational inertia force is applied to the rolling element 3 so that the sliding friction of each rolling body 3 and bearing ring 2 is reduced, hence friction can be reduced. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a bearing, and more particularly to a rolling bearing in which a plurality of rolling elements are provided so as to be freely rollable along a race.

  Conventionally, in this type of rolling bearing, a plurality of rolling elements are disposed between the outer peripheral surface of the rotating shaft as a race and the inner peripheral surface of the outer ring so that the rotating shaft can be freely rotated. I support it. As such a conventional rolling bearing, for example, in Patent Document 1, a roller-shaped rolling element is formed into a hollow cylindrical shape, thereby reducing the weight of the entire bearing. A roller bearing capable of reducing the inertial force is disclosed. Moreover, as a conventional rolling bearing of another structure, for example, in Patent Document 2, a weight of at least one rolling element among a plurality of rolling elements is set to a weight different from the weight of other rolling elements. The entire center of gravity is shifted from the center of the bearing, which causes fretting even when the bearing is subjected to repeated loads (a phenomenon in which the contacted two surfaces wear due to repeated repeated minor slips). A rolling bearing is disclosed that is difficult and can improve the life of the bearing.

JP 2002-250344 A JP-A-5-87132

  However, in the roller bearing described in Patent Document 1 as described above, the inside of the rolling element is hollow or only filled with a sponge as a non-structural body that cannot substantially receive a load. There is a possibility that sufficient strength cannot be obtained, and there is a possibility that a large load cannot be received. Further, in the rolling bearing described in Patent Document 2 as described above, for example, when the supply amount of the lubricating oil is small and the lubrication state of the sliding portion between each rolling element and the raceway is not good, this rolling element As a result, the sliding frictional force acting on each rolling element increases, and the rolling of the rolling element is hindered, resulting in an increase in friction.

  Therefore, an object of the present invention is to provide a rolling bearing capable of reducing friction.

  In order to achieve the above object, the rolling bearing according to the first aspect of the present invention is capable of rolling along an annular race and the specific gravity of the outer peripheral structure is set higher than the specific gravity of the internal structure. It is characterized by comprising a rolling element.

  In the rolling bearing according to the second aspect of the present invention, the rolling element includes a rolling element main body portion that forms the internal structure and is formed solidly, and an outer peripheral structure provided on the outer periphery of the rolling element main body portion. The specific gravity is characterized by having a weight part set higher than the rolling element main body part.

  The rolling bearing according to a third aspect of the invention is characterized in that the weight portion includes a high specific gravity member that covers an outer peripheral surface of the rolling element main body and has a specific gravity set higher than that of the rolling element main body.

  In the rolling bearing according to a fourth aspect of the present invention, the weight portion is symmetrical with respect to a high specific gravity member whose specific gravity is set higher than that of the rolling element main body portion, and a rolling direction of the rolling element in the rolling element main body portion. It is characterized by being formed by a plurality of housing parts, each of which is composed of a housing part capable of housing the high specific gravity member.

  In the rolling bearing according to the fifth aspect of the present invention, the accommodating portion is formed with an opening on an outer peripheral surface of the rolling element main body.

  In the rolling bearing according to the sixth aspect of the present invention, the rolling element body is made of at least one low specific gravity material selected from the group consisting of ceramic materials, resin materials, hard rubber materials, aluminum materials, and titanium material carbon fiber materials. On the other hand, the said weight part consists of at least 1 high specific gravity material chosen from the group which consists of steel materials, copper materials, iron materials, and sintered materials.

  In the rolling bearing according to a seventh aspect of the present invention, the rolling element is formed in a columnar shape, and the specific gravity at both ends in the central axis direction is set lower than the specific gravity at the central portion in the central axis direction.

  In the rolling bearing according to the invention according to claim 8, the rolling elements are provided at a contact portion that is provided at the central portion in the central axial direction and can contact a raceway surface formed by the raceway, and at both ends in the central axial direction. A crowning portion that cannot contact the raceway surface, and the weight portion is provided in the contact portion.

  In the rolling bearing according to the ninth aspect of the present invention, the rolling element has hollow cavities on both end surfaces in the central axis direction.

  In the rolling bearing according to the tenth aspect of the present invention, the rolling element has a solid lubricating film on the outer peripheral surface.

  The rolling bearing according to an eleventh aspect of the present invention is characterized by comprising holding means for holding a plurality of the rolling elements with a predetermined gap along the raceway.

  According to the rolling bearing according to the present invention, the sliding friction between the rolling elements and the races is reduced by the rotation inertia force acting on the rolling elements, and as a result, the friction can be reduced.

  Below, the Example of the rolling bearing which concerns on this invention is described in detail based on drawing. 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 replaced by those skilled in the art or those that are substantially the same.

  1 is a schematic sectional view in the radial direction of a bearing according to a first embodiment of the present invention, FIG. 2 is a cutaway perspective view of the bearing according to the first embodiment of the present invention, and FIG. 3 is a first embodiment of the present invention. FIG. 4 is a partial sectional view in the radial direction of the bearing according to the first embodiment of the present invention, and FIG. 5 is a rotation shaft rotational speed in the bearing according to the first embodiment of the present invention. It is a diagram which shows the relationship between a contact surface pressure and a slip ratio.

  As shown in FIG. 1 to FIG. 4, the bearing 1 as the rolling bearing according to the first embodiment is provided with a rolling part 4 having a plurality of rolling elements 3 along an annular raceway ring 2 so as to freely roll. For example, various rotation shafts such as a camshaft and a crankshaft of an internal combustion engine are rotatably supported. Hereinafter, although the bearing 1 of a present Example is demonstrated as what is applied to the rolling bearing which supports the cam shaft of an internal combustion engine rotatably, it is not restricted to this, The rolling bearing which supports the rotating shaft of various apparatuses is also applied. Applicable.

  In the following description, unless otherwise specified, “the axial direction of the bearing” refers to the axial direction of the rotating shaft supported by the bearing 1, and “the radial direction of the bearing” refers to a direction orthogonal to the axial direction. The “circumferential direction of the bearing” refers to the direction of rotation about the rotation axis.

  The bearing 1 is provided so as not to move relative to a support portion such as a cam journal attached to the cylinder head, and rotatably supports the rotating shaft 2a of the cam shaft of the internal combustion engine on the support portion. The camshaft of the internal combustion engine is for opening and closing an intake valve and an exhaust valve as valve bodies that open and close the combustion chamber of the internal combustion engine, and has a plurality of cams around the rotating shaft 2a. The camshaft can be interlocked via a crankshaft that can be rotated in accordance with the reciprocating motion of the piston of the internal combustion engine, a timing chain, and the like. That is, the camshaft rotates in synchronization with the crankshaft.

  The bearing 1 includes a ring-shaped raceway ring 2 described above, a rolling part 4 having a plurality of rolling elements 3 that can roll along the raceway ring 2, and a plurality of rolling elements 3 along the raceway ring 2. The holder 5 is provided as a holding means for holding the gap.

  The track ring 2 is constituted by a rotating shaft 2a and an outer ring 2b provided outside the rotating shaft 2a. The rotating shaft 2a is formed in a cylindrical shape and forms the axis of the above-described cam shaft. The outer ring 2b is formed in an annular shape and is provided along the outer peripheral surface of the rotary shaft 2a, and the center axis thereof is provided so as to coincide with the center axis of the rotary shaft 2a. That is, the rotating shaft 2a and the outer ring 2b are provided coaxially.

  More specifically, the rotary shaft 2a is formed with an inner raceway surface 2c along the circumferential direction on the outer circumferential surface thereof, while the outer race 2b is formed with an outer raceway surface 2d along the circumferential direction on the inner circumferential surface thereof. Is done. The rotating shaft 2a and the outer ring 2b define an annular space between the inner raceway surface 2c and the outer raceway surface 2d, and the rolling part 4 is provided in this annular space. Further, on both sides in the axial direction of the outer raceway surface 2d, flanges 2e projecting radially inward are formed. In other words, the outer raceway surface 2d is formed in a concave shape on the inner peripheral surface of the outer ring 2b.

  The rolling part 4 has a plurality of rolling elements 3. As each rolling element 3 of the present embodiment, a small cylindrical needle-shaped (needle-shaped) roller is used. The plurality of rolling elements 3 are provided in an annular space between the inner raceway surface 2 c and the outer raceway surface 2 d so that the direction of the central axis (rolling center) is parallel to the axial direction of the bearing 1. Further, the plurality of rolling elements 3 are arranged in the annular space by a cage 5 at predetermined intervals, here, at regular intervals along the circumferential direction of the inner raceway surface 2c and the outer raceway surface 2d. Each rolling element 3 is disposed by the cage 5 so that the rolling surface 3a as an outer peripheral surface thereof can come into contact with the inner raceway surface 2c and the outer raceway surface 2d, and both end surfaces thereof are on the flange 2e of the outer ring 2b. It arrange | positions so that contact | abutment is possible. Accordingly, the plurality of rolling elements 3 can roll in the annular space along the inner raceway surface 2c and the outer raceway surface 2d when the rolling surface 3a contacts the inner raceway surface 2c and the outer raceway surface 2d. At the same time, the two end surfaces are in contact with the flange 2e of the outer ring 2b, thereby preventing the shaft from falling off in the axial direction.

  More specifically, each rolling element 3 has the above-mentioned rolling surface 3a as a contact portion and a crowning portion 3b on its outer peripheral surface. The rolling surface 3a is provided at the central portion in the central axis direction of the rolling element 3, and as described above, is formed so as to be able to contact the inner raceway surface 2c and the outer raceway surface 2d formed by the raceway ring 2, while the crowning portion 3b is formed at both ends of the rolling element 3 in the central axis direction so as not to contact the inner raceway surface 2c and the outer raceway surface 2d. The crowning portion 3b is formed such that a portion where the outer peripheral surface on which the rolling surface 3a is formed and the both end surfaces 3c (bottom surfaces) in the central axis direction intersect is formed in a curved surface. Thereby, even if each rolling element 3 swings in the axial direction (axial direction), the inner raceway surface 2c by the edge of the rolling element 3 and the outer It is possible to prevent the raceway surface 2d from being damaged and the rolling element 3 itself from being damaged.

  The cage 5 holds the plurality of rolling elements 3 at regular intervals along the raceway ring 2 as described above. Furthermore, the cage 5 has a pair of annular portions 5a, a plurality of columnar separate portions 5b, and a plurality of slit-like rolling element holding portions 5c.

  The pair of annular portions 5 a are paired along the axial direction and are provided coaxially with the axis of the raceway ring 2. That is, each annular portion 5a is arranged coaxially with the central axis of the rotation shaft 2a and the outer ring 2b in the annular space between the inner raceway surface 2c and the outer raceway surface 2d. Each of the annular portions 5a is continuous in the circumferential direction so that the outer peripheral surface thereof can be in contact with the flanges 2e on both sides of the outer raceway surface 2d and the inner peripheral surface of the annular portion 5a is in contact with the inner raceway surface 2c. The entire cage 5 is guided and supported along with the plurality of rolling elements 3 along the inner raceway surface 2c and the outer raceway surface 2d.

  Each separate part 5b is constructed so as to be spanned along the axial direction between the pair of annular parts 5a. The separate part 5b is provided so as not to roll by fixing both ends to the annular part 5a. And the separate part 5b is located between the adjacent rolling elements 3, and is provided with two or more by equal intervals in the circumferential direction (space | interval according to the outer diameter of the rolling element 3 to hold | maintain).

  Each rolling element holding part 5c is a space defined by a pair of annular parts 5a opposed to the axial direction and a pair of separate parts 5b adjacent to each other in the circumferential direction. Each rolling element holding portion 5c individually accommodates one rolling element 3 such that the axis (rolling center) direction of the rolling element 3 is parallel to the axial direction of the bearing 1, and each rolling element 3 is placed on the inner track. It rolls along the circumferential direction of the surface 2c and the outer raceway surface 2d. In addition, the cage | basket 5 may form the whole with a metal or a synthetic resin integrally, and may form each part separately.

  In the bearing 1 configured as described above, in the annular space between the inner raceway surface 2c of the rotating shaft 2a and the outer raceway surface 2d of the outer ring 2b, a plurality of rolling elements 3 are arranged on the inner raceway surface 2c via lubricating oil. In contact with the outer raceway surface 2d, the inner raceway surface 2c and the outer raceway surface 2d roll on (rotate) and revolve along the inner raceway surface 2c and the outer raceway surface 2d. That is, the bearing 1 supports the rotary shaft 2a so as to be rotatable with respect to the outer ring 2b by sliding the inner raceway surface 2c and outer raceway surface 2d of the raceway ring 2 and the rolling face 3a of each rolling element 3. To do. At this time, the cage 5 is guided along the inner raceway surface 2c and the outer raceway surface 2d by the annular portion 5a along with the relative rotation of the rotating shaft 2a with respect to the outer ring 2b, and in each rolling element holding portion 5c. The rolling elements 3 housed in the bearing ring 2 are rotated relative to the raceway ring 2 while being held at regular intervals along the raceway ring 2. And the holder | retainer 5 regulates the contact with respect to the circumferential direction of the adjacent rolling elements 3 by the separate part 5b. During this time, the bearing 1 receives a radial load (a direction perpendicular to the axial direction, that is, a radial load) as a load by the rolling surface 3a of the rolling element 3 that contacts the inner raceway surface 2c and the outer raceway surface 2d. In addition, a slight axial load (axial load) can be received as a load by the end surface portion of the rolling element 3 that comes into contact with the flange 2e.

  By the way, in this type of rolling bearing 1, for example, the supply amount of lubricating oil is small, and lubrication of sliding portions between the rolling surface 3a of each rolling element 3, the inner raceway surface 2c of the raceway ring 2, and the outer raceway surface 2d is performed. When the state is not good, the rolling element 3 becomes slippery with respect to the inner raceway surface 2c and the outer raceway surface 2d, thereby increasing the sliding friction force acting on each rolling element 3, and the rolling element 3 Rolling is inhibited, and as a result, friction may increase.

Therefore, in the bearing 1 of the present embodiment, as shown in FIGS. 1 and 4, the specific gravity of the outer peripheral structure of each rolling element 3 is set higher than the specific gravity of the internal structure, thereby reducing friction. Yes.
Here, the outer peripheral structure and the internal structure of each rolling element 3 constitute a strength member that can substantially receive a load, and are not hollow members such as a sponge, for example.

  Specifically, each rolling element 3 of the rolling part 4 has a rolling element main body 31 and a weight part 32 as shown in FIGS. The rolling element body 31 has an internal structure and is formed solid, while the weight part 32 has an outer peripheral structure provided on the outer periphery of the rolling element body 31 and has a specific gravity higher than that of the rolling element body 31. Set high. Furthermore, specifically, the weight portion 32 has an annular high specific gravity member 33 as a high specific gravity member. The annular high specific gravity member 33 covers the outer peripheral surface of the rolling element main body 31 and has a specific gravity higher than that of the rolling element main body 31.

  The rolling element body 31 of this embodiment is formed in a columnar shape, while the annular high specific gravity member 33 is formed in an annular shape so as to cover the outer peripheral surface of the rolling element body 31. In this embodiment, the outer peripheral surface of the annular high specific gravity member 33 is the rolling surface 3 a of the rolling element 3. The rolling element main body 31 is made of at least one low specific gravity material selected from the group consisting of ceramic material, resin material, hard rubber material, aluminum material, titanium material carbon fiber material having a relatively small specific gravity, while the weight part. The 32 annular high specific gravity members 33 are made of at least one high specific gravity material selected from the group consisting of steel materials, copper materials, iron materials, and sintered materials.

  That is, for example, when the rolling element main body 31 is formed of a steel material (for example, SUJ2; a high carbon chrome bearing steel material), the annular high specific gravity member 33 is made of a copper material or a silver material as a substance having a larger specific gravity. What is necessary is just to form. The annular high specific gravity member 33, for example, has a specific gravity greater than that when the rolling element body 31 is formed of a ceramic material, Fe-Mn sintered material, carbon fiber resin material, or the like having a relatively low specific gravity. What is necessary is just to form with steel materials, copper materials, and iron materials as a substance. As a result, the weight portion 32 made of the annular high specific gravity member 33 is set to have a specific gravity higher than that of the rolling element main body 31, and as a result, each rolling element 3 is set to have a specific gravity of the outer peripheral portion higher than the internal specific gravity. . In this embodiment, the rolling element main body 31 is formed of a ceramic material having a relatively small specific gravity, while the annular high specific gravity member 33 is a steel material (for example, SUJ2; high carbon chrome bearing steel) having a higher specific gravity. Steel).

  Here, FIG. 5 is a diagram showing the relationship between the rotational speed of the rotating shaft 2a in the bearing 1, the contact surface pressure, and the slip ratio. Here, the slip ratio is a ratio representing the difference between the rolling (spinning) speed of the rolling element 3 and the revolution speed along the inner raceway surface 2c and the outer raceway surface 2d, and this value is small. It means that the rolling (spinning) speed and the revolution speed of the rolling element 3 are close, that is, it means that the rolling element 3 hardly slides with respect to the inner raceway surface 2c and the outer raceway surface 2d.

  In the bearing 1 configured as described above, as described above, the rotating shaft 2a forms a camshaft of the internal combustion engine and rotates in synchronization with the crankshaft of the internal combustion engine. Therefore, if the rotation speed of the crankshaft, that is, the engine rotation speed increases, the rotation speed of the rotation shaft 2a, in other words, the rotation speed of the rotation shaft 2a also increases.

  For example, when the rotational speed of the rotary shaft 2a is extremely low at the time of low load and low rotation of the internal combustion engine, the rotation of the rotary shaft 2a is slow. Therefore, the inner raceway surface 2c, the outer raceway surface 2d, and the rolling surface 3a This is so-called boundary lubrication on the sliding surface that contacts. Furthermore, since the amount of lubricating oil supplied to the bearing 1 decreases as the rotation speed decreases, the contact surface pressure (friction force) increases as shown in the upper part of FIG. At this time, the bearing temperature and the temperature of the lubricating oil film are relatively low (normal temperature) because the rotation of the rotating shaft 2a is slow and the sliding resistance is small. In such a high load state, as shown by a dotted line in the lower part of FIG. 5, in the conventional bearing, when each rolling element revolves with respect to the raceway, the slip amount with respect to the raceway increases. Increases slip rate.

  On the other hand, in the bearing 1 of the present embodiment, the specific gravity of the weight portion 32 as the outer peripheral structure of each rolling element 3 is set higher than the specific gravity of the rolling element main body 31 as the internal structure. The centrifugal force (moment of inertia) of the annular high specific gravity member 33 of the weight portion 32 at the time becomes relatively large, and the weight portions 32 respectively provided on each rolling element 3 cause the rotating inertia force to act on the rolling element 3. A large rotational force can be applied to the individual rolling elements 3. For this reason, each rolling element 3 tends to roll more easily and rolls easily with respect to the inner raceway surface 2c and the outer raceway surface 2d. That is, only a small amount of rotational force is applied to each rolling element 3, and the weight portion 32 assists the rolling element 3 as a whole by its rotational inertia force. As a result, as shown by the solid line in the lower part of FIG. 5, when each rolling element 3 revolves with respect to the raceway ring 2, the sliding amount of each rolling element 3 with respect to the inner raceway surface 2 c and the outer raceway surface 2 d becomes smaller. The slip ratio is lowered. Therefore, for example, the supply amount of the lubricating oil is small as described above, and the lubrication state of the sliding portion between the rolling surface 3a of each rolling element 3 and the inner raceway surface 2c and outer raceway surface 2d of the raceway ring 2 is not good. Even in this case, since the rolling element 3 is easy to roll, it becomes difficult to slip with respect to the inner raceway surface 2c and the outer raceway surface 2d, thereby reducing the sliding frictional force acting on each rolling element 3, and this rolling element. 3 is prevented from being inhibited. As a result, friction is reduced.

  Further, by reducing the friction, wear of the rolling element 3, the inner raceway surface 2c, the outer raceway surface 2d, and the like is reduced, and noise such as slip noise of the rolling element 3 is also reduced. Furthermore, the frictional force between the rolling element 3 and the inner raceway surface 2c and the outer raceway surface 2d is reduced, and wear of the rolling element 3, the inner raceway surface 2c, the outer raceway surface 2d, and the like is reduced. Since the contact surface pressure acting on the rolling element 3 is also reduced and the load applied to the rolling element 3 is also reduced, the diameter of the rolling element 3 can be reduced, thereby reducing the outer shape of the rolling element 3. And the mountability can be improved.

  Furthermore, since the rotational force of the rolling element 3 is improved and the contact surface pressure acting on the rolling element 3 and the inner raceway surface 2c and the outer raceway surface 2d is reduced, each rolling element accompanying the rolling of the rolling element 3 is reduced. 3 improves the lubrication property of the lubricating oil, and also from this, the lubrication state in the sliding portion between the rolling element 3 and the inner raceway surface 2c and the outer raceway surface 2d becomes good, and wear of each sliding portion is reduced. The Therefore, even if the hardness of the rotating shaft 2a and the outer ring 2b is lowered, sufficient wear resistance can be ensured. As a result, the low-cost bearing 1 can be obtained. Similarly, the lubrication state in the sliding portion between each rolling element 3 and the separating portion 5b of the cage 5 is also improved, and the wear of each sliding portion is reduced, so that the hardness of the cage 5 is reduced. In addition, sufficient wear resistance can be ensured. As a result, the cage 5 can be formed of a resin member having a relatively low specific gravity, for example, and the weight reduction of the bearing 1 can be promoted. Furthermore, since the entrainment property of the lubricating oil by each rolling element 3 accompanying the rolling of the rolling element 3 is improved and the lubricating state is improved, the amount of lubricating oil in the entire bearing 1 can be reduced, and as a result, It is also possible to reduce friction by reducing the capacity of the oil pump.

  Further, even after the rotation of the rotating shaft 2a supported by the bearing 1 is stopped, the rolling elements 3 roll by inertia (rotation) and the inner raceway surface 2c for a while due to the inertial force of the weight portion 32. Since the revolution along the outer raceway surface 2d is performed, the starting torque when the rotation of the rotating shaft 2a is started again during this time can be reduced, and therefore the friction can be reduced. In particular, in the extremely low rotation range of the rotating shaft 2a, the force for rolling the rolling elements 3 is usually small, and the rolling elements 3 are difficult to roll. Therefore, the rolling elements 3 are repeatedly moved between stationary and rolling. However, in the bearing 1 of this embodiment, the friction in this case can be reduced by the action of the rotational inertia force in the weight portion 32 as described above.

  Further, in the bearing 1 of the present embodiment, the rolling element 3 is set to have a specific gravity of the outer peripheral portion higher than the specific gravity of the inner side, but is not eccentric. Therefore, for example, the rolling element is provided with an eccentric portion, By setting the rolling center position and the center of gravity position to be shifted from each other, the rolling element 3 rolls and makes one rotation compared to the case where the centrifugal force (moment of inertia) at the time of rolling is relatively increased. In this case, the rotation (rolling) speed can be made constant. And while increasing the rotational force of this rolling element 3, since there is no bias in a rotational speed, it can receive a load equally in the rolling surface 3a of each rolling element 3, As a result, each rolling element 3 can be prevented from being locally worn, the friction can be prevented from increasing due to non-uniformity of the rolling surface 3a, and each rolling element 3 can roll flatly. It is also possible to prevent noise caused by. Moreover, since the rotation (rolling) speed of each rolling element 3 can be made constant, it is possible to prevent the rotation shaft 2a supported by the bearing 1 from being affected by rotational fluctuations.

  Further, since the contact between the adjacent rolling elements 3 in the circumferential direction is restricted by the separating portion 5 b of the cage 5, the cage 5 keeps the rolling elements 3 at regular intervals along the raceway 2. When rotating relative to the wheel 2, the adjacent rolling elements 3 can be prevented from colliding and contacting each other, and as a result, the rolling elements 3 can be prevented from being worn. Can do. In addition, since the cage 5 regulates contact between the adjacent rolling elements 3 in the circumferential direction, one rolling element 3 collides with and contacts the other rolling element 3 in the relationship between the adjacent rolling elements 3. Thus, it is possible to prevent the rolling motion from being hindered, and further, it is possible to prevent one of the rolling elements 3 from dragging the other rolling element 3 to become a sliding resistance. By setting the specific gravity of the weight part 32 higher than the specific gravity of the rolling element main body 31, the rolling of each rolling element 3 whose rotational force has increased is not hindered, and the friction is more effectively reduced.

  Furthermore, in the bearing 1, the annular high specific gravity member 33 is provided so as to cover the outer peripheral surface of the rolling element main body 31 and the weight portion 32 is configured, so that the annular high specific gravity member 33 of the rolling element main body 31 and the weight portion 32 is formed. Since both are formed in a relatively simple shape, that is, a cylindrical shape or an annular shape, the rolling elements 3 can be easily manufactured.

  Moreover, in the bearing 1 of a present Example, the rolling element main-body part 31 was formed with the ceramic material, and the weight of the outer peripheral part was formed in each rolling element 3 by forming the cyclic | annular high specific gravity member 33 of the weight part 32 with the steel material. The specific gravity of the portion 32 is set higher than the internal specific gravity, and the ceramic material having a high hardness is covered with a steel material having a relatively low hardness, so that the rolling element main body 31 formed of this ceramic material has the rotating shaft 2a and the outer ring. It is possible to prevent the battery 2 from colliding directly with the 2b or the cage 5 and attacking and wearing it. Furthermore, by covering the ceramic material having a low coefficient of thermal expansion with a steel material having a higher coefficient of thermal expansion, when the bearing 1 becomes high temperature, the rolling element body 31 of the ceramic material hardly expands, while the rotating shaft 2a. The annular high specific gravity member 33 formed of the same steel material as the outer ring 2b and the like expands together with the rotating shaft 2a and the outer ring 2b, so that the rolling surface 3a is provided between the inner raceway surface 2c and the outer raceway surface 2d. An increase in the clearance in the radial direction of the moving part 4 (so-called radial gap) is suppressed and kept constant. Thereby, since each rolling element 3 can be reduced in weight and the variation due to the temperature change of the radial gap can be suppressed, the radial length in which each rolling element 3 moves between the inner raceway surface 2c and the outer raceway surface 2d is also reduced. It can be kept constant without becoming long, and therefore, an increase in noise can be suppressed. As a result, it is possible to increase the rotational force of each rolling element 3 by the weight part 32 and to reduce the weight by using a ceramic material for the rolling element body 31. By covering with the annular high specific gravity member 33 made of steel, wear and noise at the contact portion of each rolling element 3 can be reduced.

  According to the bearing 1 which concerns on the Example of this invention demonstrated above, it can roll along the annular | circular bearing ring 2, and the specific gravity of the structure of an outer peripheral part is set higher than the specific gravity of an internal structure. A rolling element 3 is provided.

  Therefore, by setting the specific gravity of the outer peripheral portion of each rolling element 3 to be higher than the specific gravity of the internal structure, the rotational inertia force at the outer peripheral portion of each rolling element 3 is increased. Rotational inertial force at is increased, and a large rotational force can be applied to each rolling element 3. For this reason, even if a little rotational force acts on each rolling element 3, the rolling element 3 as a whole easily rolls due to the rotational inertial force, and easily rolls on the inner raceway surface 2c and the outer raceway surface 2d. The slip amount of each rolling element 3 with respect to the inner raceway surface 2c and the outer raceway surface 2d is reduced. Thereby, the sliding frictional force which acts on each rolling element 3 reduces, and it is prevented that rolling of this rolling element 3 is inhibited. As a result, friction can be reduced.

  Furthermore, according to the bearing 1 according to the embodiment of the present invention described above, the rolling element 3 includes a rolling element main body portion 31 that forms an internal structure and is solid, and an outer periphery of the rolling element main body portion 31. And a weight portion 32 having a structure of an outer peripheral portion provided in the portion and having a specific gravity set higher than that of the rolling element main body portion 31. Therefore, the structure inside the rolling element 3 is configured by the solid rolling element body 31, while the outer peripheral structure is configured by the weight part 32 having a higher specific gravity than the rolling element body 31. By doing so, since the rolling body main body portion 31 formed as a solid acts as a strength member that can substantially receive a load, the rolling body 3 having sufficient strength can be obtained. While being able to receive a big load, the rotating inertia force in each rolling element 3 can be enlarged by the weight part 32 provided in this rolling element main-body part 31. FIG.

  Furthermore, according to the bearing 1 which concerns on the Example of this invention demonstrated above, the weight part 32 covers the outer peripheral surface of the rolling element main-body part 31, and specific gravity is set higher than this rolling element main-body part 31. A specific gravity member 33 is provided. Accordingly, by configuring the weight portion 32 with the annular high specific gravity member 33 provided on the outer peripheral surface of the rolling element main body portion 31, a large rotational inertia force can be obtained, and for example, the rolling element 3 is eccentric and large. Compared with the case where a rotational inertia force is obtained, the rotation (rolling) speed of the rolling elements 3 can be made constant, and the load can be evenly received on the rolling surfaces 3 a of the respective rolling elements 3. Furthermore, since the rolling element main body 31 can be formed in a simple columnar shape, the manufacturing of each rolling element 3 is facilitated, and the manufacturing efficiency can be improved.

  Furthermore, according to the bearing 1 which concerns on the Example of this invention demonstrated above, the rolling element main-body part 31 is chosen from the group which consists of a ceramic material, a resin material, a hard rubber material, an aluminum material, and a titanium material carbon fiber material. The annular high specific gravity member 33 of the weight portion 32 is made of at least one high specific gravity material selected from the group consisting of steel materials, copper materials, iron materials, and sintered materials. Therefore, it is possible to set the weight portion 32 formed of the annular high specific gravity member 33 to have a higher specific gravity than the rolling element main body portion 31. As a result, the specific gravity of the outer peripheral portion of each rolling element 3 is set to be higher than the internal specific gravity. Can do. In particular, as in this embodiment, when the rolling element main body 31 is formed of a ceramic material and the annular high specific gravity member 33 is formed of a steel material, the rolling element main body 31 is made of a ceramic material having a low specific gravity and a low thermal expansion coefficient. Since the annular high specific gravity member 33 is formed of a steel material having a higher specific gravity than the ceramic material and a large thermal expansion coefficient, the weight portion 32 can reliably increase the rotational force of each rolling element 3, Weight reduction can be achieved by using a ceramic material for the rolling element main body 31, and furthermore, by covering the rolling element main body 31 with an annular high specific gravity member 33 made of steel, in the contact portion of each rolling element 3. Wear and noise can be reduced.

  Furthermore, according to the bearing 1 which concerns on the Example of this invention demonstrated above, the holder 5 which hold | maintains the some rolling element 3 along the track ring 2 with a predetermined clearance gap is provided. Therefore, since the contact with respect to the circumferential direction of the adjacent rolling elements 3 is controlled by the cage 5, it is possible to reliably prevent one of the adjacent rolling elements 3 from rolling while dragging the other. As a result, the specific gravity of the outer peripheral structure is set higher than the specific gravity of the internal structure, so that the rolling of each rolling element 3 whose rotational force has increased is not hindered, and the friction is more effectively reduced. be able to.

  The rolling bearing according to the above-described embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims. In the above description of the first embodiment, the rolling element main body is formed of a ceramic material and the high specific gravity member is formed of a steel material. However, the specific gravity of the high specific gravity member is not limited to this, and the rolling body main body is not limited thereto. Any combination that is higher than the specific gravity of is acceptable.

  FIG. 6 is a partial cross-sectional view of the weight portion of the bearing according to the second embodiment of the present invention, and FIG. 7 is a diagram showing the relationship between the noise frequency and the noise level in the bearing according to the second embodiment of the present invention. . The rolling bearing according to the second embodiment has substantially the same configuration as the rolling bearing according to the first embodiment, but is different from the rolling bearing according to the first embodiment in that a solid lubricating film is provided as a conforming layer. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  A bearing 201 as a rolling bearing according to the second embodiment includes a plurality of rolling elements 203. Each rolling element 203 includes a rolling element body 31 and a weight part 32, and the weight part 32 includes an annular high specific gravity member 33. The rolling element 203 further has a solid lubricating film 234 on the outer peripheral surface, as shown in FIG. The solid lubricating film 234 is provided on the outer peripheral surface (surface) of the annular high specific gravity member 33 of the weight portion 32. In this embodiment, the outer peripheral surface of the solid lubricating film 234 becomes the rolling surface 3 a of the rolling element 203. Here, the solid lubricating film 234 refers to a solid film used as a powder, thin film, or composite material that reduces friction and wear on the friction surface and prevents surface damage. The solid lubricating film 234 provided on the surface of the rolling element 203 of the present embodiment is, for example, a sintered impregnated material film, a diamond-like carbon film having a thickness of about several μm (hereinafter, particularly not shown). Unless otherwise specified, it is referred to as a “DLC film”), a resin film or the like.

  When the solid lubricant film 234 is formed of a sintered impregnated material film, the surface of the solid lubricant film 234 becomes porous, and minute uneven portions are formed on the surface. And since the rolling element 203 can hold | maintain lubricating oil to the micro unevenness | corrugation part formed in the surface of this solid lubricating film 234, the retention property of the lubricating oil in the sliding part of this bearing 201 is improved. Therefore, wear of the sliding portion can be reduced and running out of the lubricating oil can be prevented.

  When the solid lubricant film 234 is formed by a DLC film, the solid lubricant film 234 formed by the DLC film can be variously formed by a so-called arc ion plating (AIP) method, sputtering method, high-frequency plasma CVD (chemical vapor deposition) method, and the like. With this method, the film may be formed on the surface of the rolling element 203 with a thickness of about several μm. This DLC film is a carbon film containing hydrogen, has both properties of high hardness and low friction coefficient, and can exhibit wear resistance as well as excellent sliding characteristics.

  When the solid lubricating film 234 is formed of a resin film, the resin film is easier to form on the surface of the rolling element 203 than the DLC film, and thus has a relatively soft thickness of about several tens of μm. It can be provided as a film. For example, as shown by a broken line in the diagram of FIG. 7, when the solid lubricating film 234 formed of a thick resin film is not provided on the surface of the rolling element 203, noise with a high frequency (for example, 4 to 6 kHz) is provided. Becomes larger. On the other hand, as shown by the solid line in the diagram of FIG. 7, when the solid lubricating film 234 is provided on the surface of the rolling element 203 with a thick resin film, the magnitude of this high frequency noise is significantly reduced. . Even when the solid lubricant film 234 is formed by the DLC film described above, noise at a high frequency (for example, 4 to 6 kHz) is not noticeable as compared with the case where the solid lubricant film 234 is provided by a thick resin film. Reduced.

  In the bearing 201 configured as described above, by providing the solid lubricating film 234 on the outer peripheral surface (surface) of the annular high specific gravity member 33 of the weight portion 32, the wear on the surface of the rolling element 203 can be reduced. At the same time, due to the damper effect of the solid lubricant film 234, it is possible to reduce the collision noise when the rolling element 203 contacts the cage 5. Further, by providing the solid lubricating film 234 on the outer peripheral surface (surface) of the annular high specific gravity member 33 of the weight part 32, the so-called radial gap varies according to the temperature change due to the expansion of the solid lubricating film 234 at high temperature. This can be suppressed, and this can also reduce noise.

  According to the bearing 201 according to the embodiment of the present invention described above, it is possible to roll along the annular race 2 and the specific gravity of the outer peripheral structure is set higher than the specific gravity of the internal structure. A rolling element 203 is provided. Therefore, by setting the specific gravity of the outer peripheral structure of each rolling element 203 to be higher than the specific gravity of the internal structure, the rotational inertia force in the outer peripheral part of each rolling element 203 becomes large, and the individual rolling elements 203 have a large specific gravity. A rotational force can be applied. For this reason, even if a little rotational force acts on each rolling element 203, the rolling element 203 as a whole easily rolls due to the rotational inertia force, and easily rolls on the inner raceway surface 2c and the outer raceway surface 2d. The slip amount of each rolling element 203 with respect to the inner raceway surface 2c and the outer raceway surface 2d is reduced. Thereby, the sliding frictional force which acts on each rolling element 203 reduces, and it is prevented that rolling of this rolling element 203 is inhibited. As a result, friction can be reduced.

  Furthermore, according to the bearing 201 which concerns on the Example of this invention demonstrated above, the rolling element 203 has a solid lubricating film in an outer peripheral surface. Therefore, by providing the solid lubricating film 234 on the outer peripheral surface (surface) of the annular high specific gravity member 33 of the weight portion 32, the wear of the surface of the rolling element 203 can be reduced, and the rolling element 203 and the cage 5 can be reduced. The impact sound can be reduced. Moreover, it is possible to suppress the radial gap from fluctuating according to the temperature change, and it is possible to reduce the noise.

  FIG. 8 is a sectional view in the axial direction of the rolling element of the bearing according to the third embodiment of the present invention. The rolling bearing according to the third embodiment has substantially the same configuration as the rolling bearing according to the first embodiment, but the first embodiment is different in that the specific gravity at both ends in the central axial direction is set lower than the specific gravity at the central portion in the central axial direction. This is different from the rolling bearing according to the above. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  A bearing 301 as a rolling bearing according to the third embodiment includes a plurality of rolling elements 303. Each rolling element 303 includes a rolling element main body 331 and a weight part 332, and the weight part 332 includes an annular high specific gravity member 333. Here, as described in the first embodiment, the rolling surface 3a of the rolling element 303 is provided at the central portion in the central axis direction of the rolling element 303, and the inner raceway surface 2c and the outer raceway surface 2d formed by the raceway ring 2. On the other hand, the crowning portion 3b is provided at both ends in the central axis direction of the rolling element 3 so as not to contact the inner raceway surface 2c and the outer raceway surface 2d.

  As shown in FIG. 8, in the rolling element 303, the annular high specific gravity member 333 of the weight part 332 is provided on the rolling surface 3a as a contact part in the rolling element 303, while the crowning part 3b has an annular shape. The high specific gravity member 333 is not extended. In other words, the annular high specific gravity member 333 is not provided at both ends of the rolling element 303 in the central axial direction, and the rolling element 303 is in a state in which the rolling element main body 331 is exposed at both ends of the central axial direction. It has become. And the outer peripheral surface of this cyclic | annular high specific gravity member 333 makes the rolling surface 3a as a contact part in the rolling element 303. FIG. As a result, the rolling element 303 is set such that the specific gravity at both ends in the central axial direction is lower than the specific gravity in the central portion in the central axial direction.

  In the bearing 301 configured as described above, since the specific gravity of the rolling element 303 at both ends in the central axial direction is set lower than the specific gravity of the central part in the central axial direction, the rolling element 303 is close to the center in the axial direction. While the weight of the center portion (the portion where the rolling surface 3a is located along the axial direction) is relatively heavy, both ends (the portions where the crowning portion 3b is located along the axial direction) spaced apart from the axial center are formed. Therefore, the moment around the center in the axial direction acting on the rolling element 303 is reduced, and thereby the inclination and blurring of the central axis (rolling center) of the rolling element 303 can be suppressed. As a result, the inclination and blurring of the center axis (rolling center) of the rolling element 303 are reduced, so that the inner raceway surface 2c and the outer raceway surface 2d are damaged by the edges of the rolling element 303 and the rolling element 303 itself is reliably damaged. And the length of the inclined crowning portion 3b of the central axis can be shortened. Furthermore, the sliding surface pressure between the rolling surface 3a of the rolling element 303, the inner raceway surface 2c, and the outer raceway surface 2d can be made substantially uniform, that is, the load is uniformly applied to the entire rolling surface 3a of the rolling element 303. Therefore, the load per unit area can be reduced, and thus the wear resistance can be improved. Further, since the sliding surface pressure between the rolling surface 3a, the inner raceway surface 2c, and the outer raceway surface 2d becomes substantially uniform, even if the total length of the rolling element 303 is shortened, a load is received on the rolling surface 3a. Since the effective area that can be obtained can be ensured to the maximum, the bearing 301 can be made more compact and lightweight.

  According to the bearing 301 which concerns on the Example of this invention demonstrated above, it can roll along the annular | circular bearing ring 2, and the specific gravity of the structure of an outer peripheral part is set higher than the specific gravity of an internal structure. A rolling element 303 is provided. Therefore, by setting the specific gravity of the outer peripheral structure of each rolling element 303 to be higher than the specific gravity of the internal structure, the rotational inertia force in the outer peripheral part of each rolling element 303 is increased, and the individual rolling elements 303 have a large specific gravity. A rotational force can be applied. For this reason, even if a little rotational force acts on each rolling element 303, the rolling element 303 as a whole easily rolls due to the rotational inertial force, and easily rolls with respect to the inner raceway surface 2c and the outer raceway surface 2d. The slip amount of each rolling element 303 with respect to the inner raceway surface 2c and the outer raceway surface 2d is reduced. Thereby, the sliding frictional force which acts on each rolling element 303 reduces, and it is prevented that rolling of this rolling element 303 is inhibited. As a result, friction can be reduced.

  Furthermore, according to the bearing 301 which concerns on the Example of this invention demonstrated above, the rolling element 303 is formed in a column shape, and the specific gravity of a center axial direction both ends is set lower than the specific gravity of a central axial direction center part. . Therefore, in the rolling element 303, the weight of the central portion close to the axial center is relatively heavy, while both ends separated from the axial center are relatively light, so that the rolling element 303 is rotated around the axial center acting on the rolling element 303. , So that the inclination and blurring of the center axis (rolling center) of the rolling element 303 can be suppressed.

  Furthermore, according to the bearing 301 which concerns on the Example of this invention demonstrated above, the rolling element 303 can contact the inner side raceway surface 2c and the outer side raceway surface 2d which are provided in the center part of the center axis direction and which the track ring 2 forms. A rolling surface 3a and a crowning portion 3b that is provided at both ends in the central axis direction and cannot contact the inner raceway surface 2c and the outer raceway surface 2d, and the weight portion 332 is provided on the rolling surface 3a. Accordingly, the weight portion 332 is provided on the rolling surface 3a in the central portion in the central axis direction, and the weight portion 332 is not extended in the crowning portion 3b at both end portions in the central axial direction. The specific gravity of the portion can be made lower than the specific gravity of the central portion in the central axis direction.

  FIG. 9 is a sectional view in the axial direction of the rolling element of the bearing according to the fourth embodiment of the present invention. The rolling bearing according to the fourth embodiment has substantially the same configuration as the rolling bearing according to the third embodiment, but differs from the rolling bearing according to the third embodiment in that a hollow portion is provided in the rolling element. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  A bearing 401 as a rolling bearing according to the fourth embodiment includes a plurality of rolling elements 403. Each rolling element 403 includes a rolling element body 331 and a weight part 332, and the weight part 332 includes an annular high specific gravity member 333. Furthermore, as shown in FIG. 9, the rolling element 403 of the present embodiment has a pair of hollow portions 435 formed therein. The hollow portion 435 is formed in a hollow shape on both end surfaces 3c of the rolling element main body portion 331 in the central axis direction.

  In the bearing 401 configured as described above, since the pair of hollow portions 435 are provided on both end surfaces 3c in the central axis direction of the rolling element 403, the rolling element 403 can be reduced in weight and the center. Since the weights at both ends in the axial direction can be further reduced, the inclination and blurring of the central axis (rolling center) of the rolling element 403 can be more reliably suppressed. Further, even if the crowning portion 3b of the rolling element 403 contacts the inner raceway surface 2c, the outer raceway surface 2d, etc., the crowning portion 3b is deformed so as to fall down radially inward, that is, toward the cavity portion 435. It is possible to reliably prevent the inner raceway surface 2c and the outer raceway surface 2d from being damaged.

  According to the bearing 401 according to the embodiment of the present invention described above, the specific gravity of the outer peripheral structure body is set higher than the specific gravity of the inner structure body while being able to roll along the annular race 2. A rolling element 403 is provided. Accordingly, by setting the specific gravity of the outer peripheral structure of each rolling element 403 to be higher than the specific gravity of the internal structure, the rotational inertial force at the outer peripheral part of each rolling element 403 increases, and the individual rolling elements 403 have a large specific gravity. A rotational force can be applied. For this reason, even if a little rotational force is applied to each rolling element 403, the entire rolling element 403 easily rolls due to the rotational inertial force, and easily rolls with respect to the inner raceway surface 2c and the outer raceway surface 2d. The slip amount of each rolling element 403 with respect to the inner raceway surface 2c and the outer raceway surface 2d becomes small. Thereby, the sliding frictional force which acts on each rolling element 403 reduces, and it is prevented that rolling of this rolling element 403 is inhibited. As a result, friction can be reduced.

  Furthermore, according to the bearing 401 which concerns on the Example of this invention demonstrated above, the rolling element 403 has the hollow cavity part 435 in the center axial direction both end surface 3c. Accordingly, the rolling element 403 can be reduced in weight, and the weight at both ends in the central axis direction can be further reduced, so that the tilt and blurring of the central axis (rolling center) of the rolling element 403 can be more reliably suppressed. can do.

  10 is a partial sectional view in the radial direction of a bearing according to Example 5 of the present invention, FIG. 11 is a partial sectional view of a weight portion of the bearing according to Example 5 of the present invention, and FIGS. It is a fragmentary sectional view of the weight part of the modification of the bearing which concerns on Example 5 of invention. The rolling bearing according to the fifth embodiment has substantially the same configuration as the rolling bearing according to the first embodiment, but the configuration of the weight part is different from that of the rolling bearing according to the first embodiment. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  As shown in FIG. 10, the bearing 501 as the rolling bearing according to the fifth embodiment includes a plurality of rolling elements 503. Each rolling element 503 includes a rolling element body 531 and a weight part 532. The weight portion 532 is provided on the outer peripheral portion of the rolling element main body portion 531. The weight portion 532 includes a columnar high specific gravity member 533 as a high specific gravity member and a storage portion 536.

  In the present embodiment, as shown in FIG. 11, a plurality of the accommodating portions 536 are formed as cylindrical recess-shaped cavities in the outer peripheral portion of the rolling element main body portion 531. Each housing portion 536 is formed such that the cylindrical center axis is substantially parallel to the rolling axis of the rolling element 503 that passes through the rolling center position O, and is displaced radially outward from the rolling axis. Set to position. Each housing portion 536 has an equal amount of deviation from the rolling axis of each central axis to the radially outward direction. Further, the plurality of, here three, accommodating portions 536 are respectively formed at positions that are symmetric with respect to the rolling direction of the rolling element 503 in the rolling element main body 531. That is, the plurality of storage portions 536 are provided at positions that are point-symmetric with respect to the rolling center position O of each rolling element 503, and are provided at equal intervals in the circumferential direction of the rolling element 503. In other words, each housing portion 536 has an angle formed by a line connecting the cylindrical center of the circle and the rolling center position O and a line connecting the circle center of the adjacent housing portion 536 and the rolling center position O ( (Center angle) θ is provided at an equal position, and in this embodiment, since three accommodating portions 536 are provided, each angle θ is set to 120 degrees.

  The cylindrical high specific gravity member 533 is formed in a columnar shape, and is provided in each accommodating portion 536 so that the central axis of the columnar shape substantially coincides with the central axis of each accommodating portion 536. The cylindrical high specific gravity member 533 is set to have a specific gravity higher than that of the rolling element main body portion 531, similarly to the above-described annular high specific gravity member 33 (see FIG. 4). That is, the rolling element body portion 531 is made of at least one low specific gravity material selected from the group consisting of ceramic material, resin material, hard rubber material, aluminum material, titanium material carbon fiber material having a relatively small specific gravity, while being cylindrical. The high specific gravity member 533 is made of at least one high specific gravity material selected from the group consisting of steel materials, copper materials, iron materials, and sintered materials. The columnar high specific gravity member 533 may be embedded by casting, welding, caulking, or the like with respect to each accommodating portion 536 formed in the rolling element main body portion 531. Thereby, the specific gravity of the weight part 532 is set higher than that of the rolling element main body part 531, and as a result, the specific gravity of the outer peripheral part of each rolling element 503 is set higher than the internal specific gravity.

  In the bearing 501 configured as described above, the weight portion 532 is provided on the outer peripheral portion of the rolling element main body portion 531 of the rolling element 503, so that the centrifugal force (moment of inertia) in the weight part 532 during rolling is generated by the rolling element. Since the weight portions 532 respectively provided on the respective rolling elements 503 apply a rotational inertia force to the rolling elements 503, the rotating elements 503 are given a large rotational force. Can do. For this reason, each rolling element 503 is easy to roll with respect to the inner raceway surface 2c and the outer raceway surface 2d. That is, only a little rotational force is applied to each rolling element 503, and the weight portion 532 assists the rolling element 503 in its entirety by the rotational inertia force. As a result, the amount of sliding with respect to the inner raceway surface 2c and the outer raceway surface 2d of each rolling element 503 is reduced, the sliding frictional force acting on each rolling element 503 is also reduced, and the rolling of this rolling element 503 is hindered. Is prevented. As a result, friction is reduced.

  According to the bearing 501 according to the embodiment of the present invention described above, the specific gravity of the outer peripheral structure body is set higher than the specific gravity of the inner structure body while being able to roll along the annular race 2. A rolling element 503 is provided. Therefore, by setting the specific gravity of the outer peripheral structure of each rolling element 503 to be higher than the specific gravity of the internal structure, the rotational inertia force at the outer peripheral part of each rolling element 503 is increased, and the individual rolling elements 503 have a large specific gravity. A rotational force can be applied. For this reason, even if a little rotational force acts on each rolling element 503, the entire rolling element 503 easily rolls due to the rotational inertial force, and easily rolls on the inner raceway surface 2c and the outer raceway surface 2d. The slip amount of each rolling element 503 with respect to the inner raceway surface 2c and the outer raceway surface 2d is reduced. Thereby, the sliding frictional force which acts on each rolling element 503 reduces, and it is prevented that rolling of this rolling element 503 is inhibited. As a result, friction can be reduced.

  Furthermore, according to the bearing 501 according to the embodiment of the present invention described above, the weight portion 532 includes the cylindrical high specific gravity member 533 whose specific gravity is set higher than that of the rolling element main body portion 531 and the rolling element main body portion 531. A plurality of rolling elements 503 are formed at positions symmetrical to the rolling direction of the rolling elements 503, and each is constituted by a receiving portion 536 capable of receiving the cylindrical high specific gravity member 533. Therefore, the weight body 532 is configured by providing the cylindrical high specific gravity member 533 in each accommodating portion 536 formed at a position symmetrical to the rolling direction of the rolling element 503, thereby decentering the rolling element 503. Even if it is not, a large rotational inertia force can be obtained, the rotation (rolling) speed of the rolling elements 503 can be made constant, and the load can be evenly received on the rolling surface 3a of each rolling element 503. it can. Further, for example, since the volume of the high specific gravity member can be reduced as compared with the rolling element 3 of the first embodiment (see FIG. 4), both the improvement of the rotational force and the weight reduction of the rolling element 503 are balanced. Can be made.

  In the above description of the fifth embodiment, it has been described that the three accommodating portions 536 are provided, but two or four or more may be used. In the above description, the storage portion 536 has been described as being formed as a hollow in the shape of a cylindrical recess in the outer peripheral portion of the rolling element main body portion 531, but a bearing 501A according to a modification of the fifth embodiment shown in FIG. Like each rolling element 503A, each accommodating part 536A may have an opening 536a on the rolling surface 3a as the outer peripheral surface of the rolling element body 531A. That is, the weight portion 532A of the present modification includes a columnar high specific gravity member 533A and a plurality of accommodating portions 536A. Each accommodating portion 536A is formed in a cylindrical recess shape on the rolling surface 3a as the outer peripheral surface of the rolling element main body portion 531A, and has an opening 536a on the rolling surface 3a. Accordingly, since the accommodating portion 536A is formed with the opening 536a on the rolling surface 3a, a part of the lubricating oil stays in the opening 536a of the accommodating portion 536A, so that the lubricating oil in the sliding portion The retention property of can be improved. Thereby, the wear of the bearing 501A can be effectively reduced and the lubricating oil can be prevented from running out. Furthermore, noise can be effectively reduced by the lubricating oil staying in the plurality of openings 536a, and the rotating shaft 2a can be supported smoothly even when the rotating shaft 2a starts rotating.

  In addition, since each accommodating part 536 with which the bearing 501 of Example 5 mentioned above in FIG. 11 is provided does not have an opening part in the rolling surface 3a unlike the accommodating part 536A shown in FIG. 12, this rolling element 503. The rolling surface 3a can be formed on a smooth surface without irregularities, and as a result, there is an advantage that the friction can be further reduced.

  Further, as shown in FIG. 13, the rolling element 503 </ b> A of the bearing 501 </ b> A according to the modified example of the fifth embodiment has a solid lubricating film 534 similar to the solid lubricating film 234 (see FIG. 6) described in the second embodiment. It may be provided on the outer peripheral surface of 503A. The same applies to the rolling elements 503 of the bearing 501 of the fifth embodiment.

  The rolling bearing according to the above-described embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims. In the above description, the rolling bearing is described as one that rotatably supports the rotating shaft 2a of the camshaft of the internal combustion engine on a support portion such as a cam journal attached to the cylinder head. The shaft may be rotatably supported by a support portion such as a crankshaft journal attached to the cylinder block, or may support a rotating shaft of another device.

  Further, in the above description, the raceway ring 2 is constituted by the rotation shaft 2a and the outer ring 2b provided outside the rotation shaft 2a, and the rolling part 4 has the inner raceway surface 2c on the outer periphery of the rotation shaft 2a. Although described as being provided in an annular space between the outer raceway surface 2d of the outer periphery of the outer ring 2b, an inner ring coaxial with the outer ring 2b is provided on the outer periphery of the rotary shaft 2a and on the inner side of the outer ring 2b. Instead, the inner ring and the outer ring 2b may constitute a race ring. Here, the inner ring is physically interposed between the rotating shaft and the rolling element and rotates together with the rotating shaft. In this case, the inner raceway surface is provided on the outer peripheral surface of the inner ring, and the rolling portion 4 is provided in an annular space between the inner raceway surface on the outer periphery of the inner ring and the outer raceway surface 2d on the inner periphery of the outer ring 2b. The inner ring and the rotating shaft 2a may be provided integrally. Further, the outer ring 2b may be formed integrally with a support portion (housing) such as the cam journal described above.

  Further, in the above description, the plurality of rolling elements have been described as using thin cylindrical needle-like (needle-like) rollers. However, in the first, second, and fifth embodiments, a sphere or a cylindrical shape is used. Various types of rolling elements such as rollers and tapered rollers can be used. That is, in the present invention, the rolling bearing is to support the rotating shaft so as to be relatively rotatable with respect to the outer ring by rolling a rolling element interposed between the rotating shaft and the outer ring. In addition to the so-called needle roller bearings described above, the concept includes, for example, ball bearings such as deep groove ball bearings, cylindrical roller bearings, and tapered roller bearings. For example, when the rolling bearing of the present invention is applied to a ball bearing and the rolling element is formed of a spherical body, the spherical rolling element generally has a larger diameter than the case where the rolling element is formed of a needle. Therefore, the above-described weight portion can be provided at a position farther outward from the rolling center position O in the radial direction. Therefore, since the magnitude of the centrifugal force acting on the weight part can be increased, it is more effective.

  Further, the outer ring 2b and the cage 5 may be formed by combining a plurality of divided rings divided in the circumferential direction in an arc shape in order to facilitate attachment to the shaft. In the above description, the flange 2e has been described as projecting radially inward on both sides in the axial direction of the outer raceway surface 2d, but projecting radially outward on both sides in the axial direction of the inner raceway surface 2c. You may make it carry out, and you may provide in the axial direction both sides of both the inner side track surface 2c and the outer side track surface 2d.

  The plurality of rolling elements 3 have been described on the assumption that the rolling surfaces 3a can contact the inner raceway surface 2c and the outer raceway surface 2d via a lubricant, respectively. The lubricant used here is a material (for example, mineral oil, diester oil, polyvalent ester oil, or silicon oil as a base oil) as long as it contributes to prevention of seizure in rolling bearings, reduction of friction, etc., and improvement of bearing performance. And the like (for example, gas, liquid, solid, semi-solid, etc.) are not limited.

  As described above, the rolling bearing according to the present invention is intended to reduce friction, and is suitable for application to various rolling bearings other than the rolling bearing used in the internal combustion engine.

It is a schematic sectional drawing of the radial direction of the bearing which concerns on Example 1 of this invention. It is a notch perspective view of the bearing which concerns on Example 1 of this invention. It is a fragmentary sectional view of the axial direction of the bearing which concerns on Example 1 of this invention. It is a fragmentary sectional view of the radial direction of the bearing which concerns on Example 1 of this invention. It is a diagram which shows the relationship between the rotating shaft rotational speed in a bearing which concerns on Example 1 of this invention, a contact surface pressure, and a slip ratio. It is a fragmentary sectional view of the weight part of the bearing which concerns on Example 2 of this invention. It is a diagram which shows the relationship between the noise frequency in the bearing which concerns on Example 2 of this invention, and the magnitude of a noise. It is sectional drawing of the axial direction of the rolling element of the bearing which concerns on Example 3 of this invention. It is sectional drawing of the axial direction of the rolling element of the bearing which concerns on Example 4 of this invention. It is a fragmentary sectional view of the radial direction of the bearing which concerns on Example 5 of this invention. It is a fragmentary sectional view of the weight part of the bearing which concerns on Example 5 of this invention. It is a fragmentary sectional view of the weight part of the modification of the bearing which concerns on Example 5 of this invention. It is a fragmentary sectional view of the weight part of the modification of the bearing which concerns on Example 5 of this invention.

Explanation of symbols

1,201,301,401,501,501A Bearing (Rolling bearing)
2 Raceway 2a Rotating shaft 2b Outer race 2c Inner raceway (Raceway)
2d Outer raceway surface (Raceway surface)
2e collar 3, 203, 303, 403, 503, 503A rolling element 3a rolling surface (contact part)
3b Crowning part 3c End face 4 Rolling part 5 Cage (holding means)
5a Annular part 5b Separate part 5c Rolling body holding part 31, 331, 531, 531A Rolling body main body part 32, 332, 532, 532A Weight part 33, 333 Annular high specific gravity member (high specific gravity member)
234, 534 Solid lubricating film 435 Cavity 533, 533A Cylindrical high specific gravity member (high specific gravity member)
536, 536A accommodating portion 536a opening

Claims (11)

It is characterized by comprising a rolling element that can roll along an annular race and whose specific gravity of the outer peripheral structure is set higher than the specific gravity of the internal structure.
Rolling bearing. The rolling element has a rolling body main body portion that is formed as a solid body and has an outer peripheral structure provided on the outer periphery of the rolling body main body portion, and has a specific gravity higher than that of the rolling body main body portion. Characterized by having a weight part
The rolling bearing according to claim 1. The weight portion includes a high specific gravity member that covers an outer peripheral surface of the rolling element main body and has a specific gravity set higher than that of the rolling element main body.
The rolling bearing according to claim 2. A plurality of the weight parts are formed at a high specific gravity member whose specific gravity is set higher than that of the rolling element main body part, and at a position symmetric with respect to the rolling direction of the rolling element in the rolling element main body part. It is characterized by being constituted by an accommodating part capable of accommodating a specific gravity member,
The rolling bearing according to claim 2. The housing part is formed to have an opening on the outer peripheral surface of the rolling element body part,
The rolling bearing according to claim 4. While the rolling element body portion is made of at least one low specific gravity material selected from the group consisting of ceramic material, resin material, hard rubber material, aluminum material, titanium material carbon fiber material,
The weight part is composed of at least one high specific gravity material selected from the group consisting of steel materials, copper materials, iron materials, sintered materials,
The rolling bearing according to any one of claims 2 to 5. The rolling element is formed in a columnar shape, and the specific gravity of both ends in the central axis direction is set lower than the specific gravity of the central portion in the central axis direction,
The rolling bearing according to any one of claims 2 to 6. The rolling element includes a contact portion that is provided at a central portion in the central axial direction and that can contact a raceway surface formed by the raceway, and a crowning portion that is provided at both ends of the central axial direction and cannot contact the raceway surface. Have
The weight part is provided in the contact part,
The rolling bearing according to claim 7. The rolling element has hollow cavities on both end surfaces in the central axis direction,
The rolling bearing according to claim 7 or 8. The rolling element has a solid lubricating film on the outer peripheral surface,
The rolling bearing according to any one of claims 1 to 9. Characterized by comprising holding means for holding a plurality of the rolling elements along the raceway with a predetermined gap,
The rolling bearing according to any one of claims 1 to 10.

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