JP4935447B2 - Rolling bearing - Google Patents

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 rolling bearing, for example, in Patent Document 1, the weight of at least one rolling element among a plurality of rolling elements is set to a weight different from the weight of the other rolling elements, whereby the center of gravity of the entire bearing is set as a bearing. Because of this, even when the bearing is subjected to repeated loads, it is difficult for fretting (a phenomenon in which the two contacted surfaces wear due to repeated minor slippage), and the life of the bearing A rolling bearing capable of improving the speed is disclosed.

JP-A-5-87132

  However, in such a rolling bearing described in Patent Document 1, for example, when the supply amount of lubricating oil is small and the lubrication state of the sliding portion between each rolling element and the raceway is not good, It becomes easy to slip with respect to the raceway, and thereby, the sliding frictional force acting on each rolling element increases, and the rolling of the rolling element is hindered. As a result, the friction may increase.

  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 a rolling element that is capable of rolling along an annular race and whose rolling center position and center of gravity are shifted from each other. The rolling element has a rolling element main body part and an eccentric part that is provided at a position shifted from the rolling center position in the rolling element main body part and has a specific gravity different from that of the rolling element main body part. The eccentric portion includes a high specific gravity member whose specific gravity is set higher than that of the rolling element main body portion, and a housing portion that is formed in the rolling body main body portion and can accommodate the high specific gravity member. To do.

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

The rolling bearing according to the invention of claim 3 is characterized in that the rolling element has a conforming layer on an outer peripheral surface.

The rolling bearing according to a fourth aspect of the 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 rolling center position and the center of gravity position are deviated from each other, so that the sliding friction between each rolling element and the raceway is reduced by the rotational inertia force acting on the rolling element. As a result, 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 sectional view of the eccentric portion of the bearing according to the first embodiment of the present invention. FIG. 6 is a diagram showing the relationship between the rotational speed of the rotating shaft, the contact surface pressure, and the slip ratio in the bearing according to Embodiment 1 of the present invention, and FIG. It is a fragmentary sectional view of the radial direction.

  As shown in FIGS. 1 to 5, 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 thin 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 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.

  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, 4, and 5, a position where the rolling center position (rolling center position O) and the gravity center position O ′ of each rolling element 3 are shifted from each other. By setting to, the friction is reduced.

  Specifically, each rolling element 3 of the rolling part 4 includes a rolling element body 31 and an eccentric part 32 as shown in FIGS. 4 and 5. The eccentric portion 32 is provided at a position shifted from the rolling center position O in the rolling element main body portion 31. The eccentric portion 32 includes a columnar high specific gravity member 33 as a high specific gravity member and a storage portion 34.

  In this embodiment, the accommodating portion 34 is formed in a cylindrical recess shape on the rolling surface 3a as the outer peripheral surface of the rolling element main body 31, and has an opening 34a (see FIG. 5) on the rolling surface 3a. The accommodating portion 34 is formed such that the cylindrical center axis is substantially parallel to the rolling axis of the rolling element 3 that passes through the rolling center position O, and is displaced radially outward from the rolling axis. Set to position.

  The cylindrical high specific gravity member 33 is formed in a cylindrical shape and is accommodated in the accommodating portion 34 so that the central axis of the cylindrical shape substantially coincides with the central axis of the accommodating portion 34. The cylindrical high specific gravity member 33 is set to have a specific gravity higher than that of the rolling element main body 31. 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 cylindrical high specific gravity member 33 is formed of a copper material or a silver material as a material having a higher specific gravity. do it. Moreover, when the cylindrical high specific gravity member 33 is formed of, for example, a ceramic material having a relatively small specific gravity, an Fe-Mn sintered material, a carbon fiber based resin material, or the like, the specific gravity is higher than this. What is necessary is just to form with a steel material, a copper material, and a silver material as a big substance. The columnar high specific gravity member 33 may be embedded by casting, welding, caulking or the like with respect to the accommodating portion 34 formed in the rolling element main body portion 31. As a result, the eccentric portion 32 is set to have a specific gravity different from that of the rolling body main body portion 31, in this case, a high specific gravity. As a result, each rolling body 3 is located at a position where the rolling center position O and the gravity center position O ′ are shifted. Is set.

  Here, FIG. 6 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 is also reduced as the rotation is slower, the contact surface pressure (friction force) is increased 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 the dotted line in the lower part of FIG. 6, in the conventional bearing, when each rolling element revolves with respect to the raceway, the slip amount with respect to this raceway increases. Increases slip rate.

  On the other hand, in the bearing 1 of the present embodiment, the rolling center position O and the gravity center position O ′ of each rolling element 3 are set to be shifted from each other, and the gravity center of each rolling element 3 is eccentric by the eccentric portion 32. Thus, the centrifugal force (moment of inertia) in the cylindrical high specific gravity member 33 at the time of rolling becomes relatively large, and the eccentric portion 32 provided on each rolling element 3 applies the rotational inertial force to the rolling element 3. Therefore, a large rotational force can be applied to each rolling element 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, the eccentric portion 32 assists the rolling of the entire rolling element 3 by the rotational inertia force only by applying a slight rotational force to each rolling element 3. As a result, as shown by the solid line in the lower part of FIG. 6, when each rolling element 3 revolves with respect to the raceway ring 2, the amount of slip of each rolling element 3 with respect to the inner raceway surface 2 c and the outer raceway surface 2 d decreases. 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.

  In addition, since the housing portion 34 is formed with the opening portion 34a on the rolling surface 3a of the rolling element body portion 31, the bearing 1 has an opening in the housing portion 34 that is recessed with respect to the rolling surface 3a. A part of the lubricating oil stays and is retained in the portion 34a. And by retaining a part of lubricating oil in this accommodating part 34, the retention property of the lubricating oil in the sliding part of this bearing 1 can be improved, For this reason, running out of lubricating oil is prevented. Thus, wear of the sliding portion can be further reduced, and seizure can be prevented. Further, even when the rotation of the rotating shaft 2a supported by the bearing 1 has been stopped for a long time and the rotation is started, the rotating shaft 2a is smoothly supported by the lubricating oil staying in the housing portion 34. can do.

  And since the contact with respect to the circumferential direction of the adjacent rolling elements 3 is controlled by the separate part 5b of the retainer 5, the retainer 5 keeps the rolling elements 3 along the track ring 2 at equal intervals. 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 rolling center position O and the gravity center position O ′ to be shifted from each other, the rolling of each rolling element 3 whose rotational force has increased is not hindered, and the friction is more effectively reduced.

  According to the bearing 1 which concerns on the Example of this invention demonstrated above, it can roll along the annular | circular raceway ring 2, and the position where the rolling center position O and gravity center position O 'of this rolling shifted | deviated. Provided with rolling elements 3 set to.

  Therefore, by setting the rolling center position O and the gravity center position O ′ of each rolling element 3 to be shifted from each other, the center of gravity of each rolling element 3 is eccentric with respect to the rolling center position O. The rotational inertia force in each rolling element 3 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 which concerns on the Example of this invention demonstrated above, each rolling element 3 is in the position shifted | deviated from the rolling body main-body part 31 and the rolling center position O in this rolling-element main body part 31. FIG. And an eccentric portion 32 that is provided and has a specific gravity different from that of the rolling element main body portion. Therefore, by providing the eccentric part 32 set to a specific gravity different from that of the rolling element main body 31 at a position shifted from the rolling center position O in the rolling element main body 31, the rolling center position O of each rolling element 3 is provided. And the center-of-gravity position O ′ can be set to be shifted from each other, and the rotational inertia force can be reliably applied to the rolling element 3.

  Furthermore, according to the bearing 1 which concerns on the Example of this invention demonstrated above, the eccentric part 32 has the cylindrical high specific gravity member 33 in which specific gravity is set higher than the rolling element main-body part 31, and the rolling element main-body part 31. The housing portion 34 is formed and can accommodate the cylindrical high specific gravity member 33. Therefore, by providing the cylindrical high specific gravity member 33 having a specific gravity higher than that of the rolling element main body 31 in the accommodating part 34 formed in the rolling element main body 31 at the eccentric part 32, the rolling element 3 at the time of rolling is provided. The centrifugal force (moment of inertia) in the cylindrical high specific gravity member 33 becomes relatively large, and the rotary inertia force acts on the rolling element 3 by the cylindrical high specific gravity member 33 of the eccentric portion 32 provided in each rolling element 3. Therefore, a large rotational force can be applied to each rolling element 3. As a result, the eccentric portion 32 can assist the rolling of the entire rolling element 3 by the rotational inertia force of the cylindrical high specific gravity member 33 only by applying a slight rotational force to each rolling element 3. Furthermore, since the volume of the high specific gravity portion in the rolling element 3 can be relatively reduced, the weight of the entire rolling element 3 can be reduced, and noise during rolling of the rolling element 3 can also be suppressed. .

  Furthermore, according to the bearing 1 which concerns on the Example of this invention demonstrated above, the accommodating part 34 has the opening part 34a in the rolling surface 3a of the rolling element main-body part 31, and is formed. Therefore, since the accommodating portion 34 is formed with the opening 34a on the rolling surface 3a, a part of the lubricating oil stays in the opening 34a of the accommodating portion 34, so that the lubricating oil in the sliding portion The retention property of can be improved. Thereby, the wear of the bearing 1 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 34a, and the rotating shaft 2a can be supported smoothly even when the rotating shaft 2a starts rotating.

  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, rolling of each rolling element 3 whose rotational force has increased by setting the rolling center position O and the gravity center position O ′ of the rolling element 3 to be shifted from each other is not hindered, and more effectively. Friction can be reduced.

  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.

  FIG. 7 is a partial cross-sectional view in the radial direction of a bearing 1A as a rolling bearing according to a modification of the present embodiment. In the above description of the bearing 1 of the first embodiment, the housing portion 34 is described as having the opening 34a on the rolling surface 3a. However, the housing portion 34A of the bearing 1A is formed on the rolling surface 3a. Does not have an opening. That is, each rolling element 3A of the bearing 1A has a rolling element main body 31A and an eccentric part 32A. The eccentric portion 32A includes a cylindrical high specific gravity member 33A and a housing portion 34A. And this accommodating part 34A is formed in the inside of rolling-element main-body part 31A as a cylindrical cavity. The accommodating portion 34A is formed such that the cylindrical center axis is substantially parallel to the rolling axis of the rolling element 3 passing through the rolling center position O, and shifted radially outward from the rolling axis. Set to position. The columnar high specific gravity member 33A is provided in the accommodating portion 34A formed as a cavity inside the rolling element main body portion 31A. Therefore, by configuring the eccentric part 32A of the rolling element 3A in this way, the rotational inertia force can be increased by the eccentric part 32A and the rolling surface 3a does not have an opening. The rolling surface 3a can be formed on a smooth surface without irregularities, and as a result, the friction can be further reduced.

  In the above description of the first embodiment, the eccentric portion is described as including the columnar high specific gravity member 33 and the accommodating portion 34, but is not limited thereto. For example, in the case of the rolling element 3A of the bearing 1A described with reference to FIG. 7, the eccentric part 32A is configured only by the accommodating part 34A formed as a cavity inside the rolling element main body 31A, and the cylindrical high specific gravity member 33A is not provided. It is good. Even in this case, the rolling element 3A has a different specific gravity between the eccentric part 32A and the rolling element main body 31A because the accommodating part 34A is hollow, and as a result, the rolling center position O of the rolling element 3A is different. And the center of gravity O ′ can be set to be shifted from each other, and the center and the outer periphery of the rolling element are set to have different specific gravities. However, as described above, the columnar high specific gravity member 33A is provided with the cylindrical high specific gravity member 33A in the accommodating portion 34A, for example, as compared with the case where the eccentric portion 32A is formed only by the accommodating portion 34A. Therefore, the durability of the entire rolling element 3A can be improved. In addition, sufficient intensity | strength can be ensured even if it does not provide the column-shaped high specific gravity member 33A by forming the rolling-element main-body part 31A with a highly durable ceramic material, for example. In this case, since the cylindrical high specific gravity member 33A is not provided, the rolling element 3A can be further reduced in weight.

  In the above description, the eccentric portion 32 has been described as including one cylindrical high specific gravity member 33 and one accommodating portion 34, but a plurality of sets may be provided. In this case, each housing portion has an angle (center) formed by a line connecting the cylindrical circle center and the rolling center position O and a line connecting the circle center of the adjacent housing portion and the rolling center position O. The eccentric portion of the present invention can be configured by setting the position where the corners are not uniform or the amount of deviation of the central axis of each housing portion from the rolling axis to the radially outward direction is different. Thereby, the rotational inertia force in an eccentric part can further be enlarged by accommodating a high specific gravity member in a some accommodating part, respectively.

  FIG. 8 is a cross-sectional view of the eccentric portion of 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 it includes 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 main body 31 and an eccentric part 32, and the eccentric part 32 includes a cylindrical high specific gravity member 33 and an accommodating part 34. And this rolling element 203 has the sprayed film 237 as a conforming layer in an outer peripheral surface. In this embodiment, the outer peripheral surface of the sprayed film 237 becomes the rolling surface 3 a of the rolling element 203. The sprayed film 237 is formed by spraying manganese, resin, DLC (Diamond-Like-Carbon), iron, or the like on the outer peripheral surface of the rolling element main body 31 and has a relatively high specific gravity, wear resistance, and the like.

  In the bearing 201 configured as described above, the centrifugal force (moment of inertia) in the cylindrical high specific gravity member 33 at the time of rolling is relatively large because the center of gravity of each rolling element 203 is decentered by the eccentric portion 32. Thus, a large rotational force can be applied to each rolling element 203. 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 rotational force is applied to each rolling element 203, and this eccentric portion 32 assists the rolling element 3 as a whole by its 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 203 is reduced, the sliding frictional force acting on each rolling element 203 is also reduced, and the rolling of this rolling element 203 is inhibited. Is prevented. As a result, friction is reduced.

  At this time, since each rolling element 203 is eccentric by the eccentric portion 32, each rolling element 203 rolls and makes one rotation, even if the rotation (rolling) speed is biased, each rolling element 203 is rotated. By providing the sprayed film 237 on the moving body 203, it is possible to prevent each rolling element 203 from being locally worn, and to prevent an increase in friction due to non-uniform rolling surfaces 3a. In addition, it is possible to prevent noise caused by the rolling elements 203 rolling flat. Further, by providing the sprayed film 237, the wear resistance of the rolling elements 203 is improved, and by providing the eccentric portion 32 as described above, the sliding of each rolling element 203 with respect to the inner raceway surface 2c and the outer raceway surface 2d. Since the amount is also small, a configuration in which no lubricating oil is used for the sliding portion of the bearing 201 can be achieved. Furthermore, even when a lubricating oil is used, an ultra-low viscosity lubricating oil can be used, and the friction can be further reduced and the effect of reducing the starting torque can be remarkably improved.

  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 a position where the rolling center position O and the gravity center position O ′ of the rolling are shifted. The rolling element 203 set in (1) is provided. Therefore, by setting the rolling center position O and the gravity center position O ′ of each rolling element 203 to be shifted from each other, the center of gravity of each rolling element 203 is decentered with respect to the rolling center position O. The rotational inertia force in each rolling element 203 becomes large, and a large rotational force can be given to each rolling element 203. 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 the thermal spray film 237 on an outer peripheral surface. Therefore, even if the rotation (rolling) speed in one rotation of each rolling element 203 is biased, the thermal spray film 237 is provided on each rolling element 203 to prevent each rolling element 203 from being locally worn. Thus, an increase in friction due to non-uniform rolling surface 3a can be prevented.

  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 3 have been described as using thin cylindrical needle-shaped (needle-shaped) rollers, but various rolling elements such as spheres, cylindrical rollers, and tapered rollers can be used. is there. 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 eccentric part and weight part can be provided at a position away from the rolling center position O in the radially outward direction. Therefore, since the magnitude of the centrifugal force acting on the eccentric part and 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 sectional drawing of the eccentric part 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 radial direction of the modification of the bearing which concerns on Example 1 of this invention. It is sectional drawing of the eccentric part of the bearing which concerns on Example 2 of this invention.

Explanation of symbols

1, 1A, 201 Bearing (Rolling bearing)
2 bearing ring 2a rotating shaft 2b outer ring 2c inner raceway surface 2d outer raceway surface 2e flange 3, 3A, 203 rolling element 3a rolling surface 4 rolling part 5 cage (holding means)
5a annular part 5b separate part 5c rolling element holding part 31, 31A rolling element body part 32, 32A eccentric part 33, 33A cylindrical high specific gravity member (high specific gravity member)
34, 34A accommodating portion 34a opening 237 sprayed film

Claims (4)

A rolling element that is capable of rolling along an annular raceway and that is set at a position where a rolling center position and a center of gravity position are deviated from each other , the rolling element comprising: a rolling element main body portion; and And an eccentric portion set at a specific gravity different from that of the rolling element main body, and the eccentric portion is set to have a specific gravity higher than that of the rolling element main body. It is constituted by a high specific gravity member and an accommodating portion that is formed in the rolling element main body and can accommodate the high specific gravity member .
Rolling bearing. 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 1 . The rolling element has a conforming layer on the outer peripheral surface,
The rolling bearing according to claim 1 or 2 . 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 3 .

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