JP2008281178A - Ball bearing device for differential - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball bearing device for a differential, which reduces frictional resistance of balls, an outer ring and an inner ring, reduces a contact area of a rolling surface of the balls, an inner ring raceway surface and an outer ring raceway surface, and also reduces a rotational torque of a bearing. <P>SOLUTION: A differential device is provided with a differential case 51, a differential deceleration mechanism 52, a pinion gear 54 and a pinion shaft 55. The ball bearing device for differential rotatably supports the pinion shaft 55 in the differential case. The ball bearing device is a tandem type angular contact ball bearing device provided with the inner ring 12, the outer ring 14, a plurality of rows of ball groups 15, 16 arranged between raceway surfaces of respective rows of the inner ring 12 and the outer ring 14 with respectively different pitch circle diameters and retainers 19, 20 for retaining the balls 27, 28 of the ball groups 15, 16. The balls 27, 28 are made of ceramics. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ball bearing device for a differential.

  As the bearing, there is an angular ball bearing capable of applying a radial load and an axial load in one direction. The ball and the inner ring / outer ring have a contact angle. The larger the contact angle, the greater the load capacity of the axial load, and the smaller the contact angle, the more advantageous for high-speed rotation.

  In order to reduce rolling resistance, there is a double row angular contact ball bearing (tandem type) as an alternative to a tapered roller bearing. In addition, there is one in which this tandem type double row angular ball bearing is used for an automobile transfer (Patent Document 1). A transfer is a 4WD vehicle that transmits power from the transmission separately to the front and rear wheels. Usually, a differential device (differential device) is also installed together. I'm calling. Double-row angular contact ball bearings are single-row angular contact ball bearings combined on the back, with the inner ring and outer ring integrated into one body, and can carry axial loads in both directions, and have load capacity for moment loads. It is.

  As shown in FIG. 3, the tandem type double-row angular ball bearing includes an inner ring 2 having double-row raceway surfaces 1a and 1b, and double-row raceway surfaces 3a and 3b corresponding to the raceway surfaces 1a and 1b of the inner ring 2. And an outer ring 4 and double-row ball groups 5 and 6 interposed between the raceways 1a, 1b, 3a and 3b of each row of the inner ring 2 and the outer ring 4. The double row ball groups 5 and 6 have different pitch circle diameters. The balls 7 and 8 of each ball group 5 and 6 are held by cages 9 and 10 disposed between the inner ring 2 and the outer ring 4.

  As shown in FIG. 4, the differential device described in Patent Document 1 includes a differential case 101, a differential reduction mechanism (not shown) disposed in the differential case 101, and a ring gear (see FIG. And a pinion shaft 105 that supports the pinion gear 104. The pinion shaft 105 is rotatably supported in the differential case 101 via bearings 106 and 107.

  And tandem type double row angular contact ball bearings are used for the bearings 106 and 107, respectively. One bearing 106 disposed on the pinion gear 104 side has a large-diameter side end surface 2a of the inner ring 2 (an end surface protruding to the pinion gear 104 side from the outer ring 4) press-contacts the end surface 104a of the pinion gear 104, and The end surface 4 a on the side opposite to the pinion gear is in pressure contact with a step surface 108 formed on the inner surface of the case 101.

  The other bearing 107 has a large-diameter side end surface 2a of the inner ring 2 (an end surface protruding to the side opposite to the pinion gear from the outer ring 4) press-contacts the end edge 100a of the pinion flange 100, and an end surface 4a of the outer ring 4 on the pinion gear side. The step 101 is in pressure contact with the step surface 109 formed on the inner surface of the case 101. Further, the pinion shaft 105 has a large diameter on the pinion gear 104 side to form a stepped portion 105a, and a sleeve 110 is interposed between the stepped portion 105a and the inner ring 2 of the other bearing 107.

  In this case, a preload is applied to the bearings 106 and 107 via the pinion flange 100 by screwing a nut member (not shown) to the threaded portion 111 at the end of the pinion shaft 105. That is, by applying preload to the bearings 106 and 107, the rigidity of the bearing support structure is increased, the position of the pinion shaft 105 is stabilized, and the meshing with the ring gear is improved.

By the way, the curvature radius of the cross-sectional shape of the inner ring raceway and the outer ring raceway is slightly larger than the curvature radius of the raceway surface of each ball. That is, conventionally, the radius of curvature of the cross-sectional shape of the inner ring raceway is 51% to 52% of the outer diameter of each ball, and the radius of curvature of the cross-sectional shape of the outer ring raceway is 54% to 56% of each ball. . The radius of curvature of the cross-sectional shape of the inner ring raceway is smaller than the radius of curvature of the outer ring raceway. The shape of the inner ring raceway in the circumferential direction is a convex arc, and the shape of the outer ring raceway in the circumferential direction is a concave arc. Because there is. That is, in order to prevent a difference in the contact area between the rolling surface of each ball and the inner ring raceway surface and the outer ring raceway surface regardless of the difference in shape.
Special table 2002-523710

  Conventionally, since steel balls are generally used, the contact between the balls and the outer ring and the inner ring is the contact between the same type of metals. When the same kind of metals come into contact with each other, the frictional resistance at the contact portion increases and the amount of elastic deformation increases. This increases the rotational torque of the bearing.

  In view of the above problems, the present invention can reduce the frictional resistance between the ball and the outer ring and the inner ring, and reduce the contact area between the ball rolling surface and the inner ring raceway surface and the outer ring raceway surface. And a differential ball bearing device capable of reducing the rotational torque of the bearing.

  A differential ball bearing device according to the present invention includes a differential case, a differential reduction mechanism disposed in the differential case, a pinion gear that meshes with a ring gear of the differential reduction mechanism, and a pinion shaft that supports the pinion gear. In a differential device, a ball bearing device for a differential that rotatably supports the pinion shaft in a differential case, wherein the ball bearing device corresponds to an inner ring having a double row raceway surface and a raceway surface of the inner ring. An outer ring having a double-row raceway surface, a double-row ball group interposed between the raceway surfaces of each row of the inner ring and the outer ring with different pitch circle diameters, and a cage for holding the balls of the ball group A tandem angular contact ball bearing device comprising: the ball is made of ceramics.

  According to the differential ball bearing device of the present invention, since the ball is made of ceramics, the ball rolling surface and the outer ring raceway are compared with a ball bearing using a steel ball that has been generally used conventionally. In addition, it is possible to reduce rolling friction that acts on the contact portion with the inner ring raceway. In other words, since ceramic balls and outer rings and inner rings made of hard metal such as steel are brought into contact with each other, different materials are in contact with each other. Is reduced. At the same time, ceramic balls have a smaller amount of elastic deformation than steel balls, so that the Hertzian contact ellipse present at the abutting portion is reduced. Furthermore, since the specific gravity is smaller than that of metal and the inertial mass is small, the rolling resistance of the ceramic ball itself is also small.

  The radius of curvature of the cross-sectional shape of the outer ring raceway is 54% or more and less than 56% of the outer diameter of each ball, and the radius of curvature of the cross-sectional shape of the inner ring raceway is 52.5% or more and 56% of the outer diameter of each ball. Can be less than That is, the radius of curvature of the cross-sectional shape of the inner ring raceway is larger than that of the conventional structure (about 51 to 52% of the outer diameter of the ball) and 52.5% or more, and the radius of curvature of the cross-sectional shape of the outer ring raceway is It can be the same as the conventional one. Thereby, the contact ellipse of the Hertz which exists in a contact part can be made small.

  The curvature radius of the cross-sectional shape of the outer ring raceway is 53% or more and less than 55% of the outer diameter of each ball, and the curvature radius of the cross-sectional shape of the inner ring raceway is 50.5% or more and 52% of the outer diameter of each ball. Can be less than In this case, in particular, the curvature radius of the cross-sectional shape of the inner ring raceway is preferably 50.5% or more and 51.5% or less of each ball diameter, and the curvature radius of the cross-sectional shape of the outer ring raceway is preferably 53% or more and 54% or less of each ball diameter. Thus, the contact surface stress can be reduced by setting the curvature radius of the raceway surface of the inner ring to 50.5% or more and less than 52% of the ball diameter. Further, the outer ring raceway surface can be 53% or more and less than 55%. Thereby, a contact area can be made small and a differential slip can be reduced. As described above, since the axial rigidity is reduced by increasing the curvature radius of the outer ring raceway surface, the upper limit of the curvature is provided so as not to increase too much.

  The cage can be made of a synthetic resin. Thereby, compared with the conventional steel (SPCC) cage, the friction between the rolling elements and the cage pocket is reduced, and the cage itself is also lightweight, so the rotational torque is reduced. The material of the synthetic resin cage is preferably a material in which a synthetic resin such as nylon, polyamide, polyacetal, phenol, polypropylene, polyphenylene sulfide or the like is reinforced with glass fiber or the like. ) And a base material added with glass fiber as a reinforcing material are preferable from the viewpoint of strength and friction performance.

  The differential ball bearing device of the present invention is lighter than a conventional bearing, can reduce the contact area, and can realize a reduction in torque of the bearing.

  In particular, since the Hertz contact ellipse present in the contact portion can be reduced, differential slip and the like can be reduced, and the rotational torque can be reduced and the bearing life can be extended. Further, since the radius of curvature of the cross-sectional shape of the outer ring raceway is the same as that of the conventional one, the existing outer ring can be used, and the productivity can be improved and the cost can be reduced.

  By making the cage made of synthetic resin, it is possible to reduce the torque by reducing the weight and to prevent the generation of heat generation and wear powder, thereby extending the service life. Further, heat generation inside the bearing during rapid acceleration / deceleration rotation, which is one of the causes of poor lubrication and seizure, can be suppressed. Furthermore, in the cage made of synthetic resin, generation of iron-based wear powder generated in the steel cage is suppressed, which is effective for extending the life of the bearing.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a differential ball bearing device according to the present invention. This bearing device has an inner ring 12 having double-row raceway surfaces 11a and 11b, and a double-row raceway surface corresponding to the raceway surfaces 11a and 11b of the inner ring 12. The outer ring 14 having 13a and 13b, and the double-row ball groups 15 and 16 interposed between the raceways 11a, 11b, 13a and 13b of each row of the inner ring 12 and the outer ring 14 are provided.

  The inner ring 12 has a first cutout portion 21 formed on the outer diameter surface thereof, and a second cutout portion 22 formed in the first cutout portion 21. And the edge part by the side of the 2nd notch of the 1st notch part 21 is made into the said track surface 11a, and the 2nd notch part 22 is made into the said track surface 11b.

  The outer ring 14 has a first notch 24 formed on the inner diameter surface thereof, and a second notch 25 is formed in the first notch 24. The end of the first notch 24 on the second notch side is the track surface 13b, and the second notch 25 is the track surface 13a.

  The ball groups 15 and 16 are held by holders 19 and 20, respectively. The cages 19 and 20 are made of a synthetic resin formed in a tapered cylindrical ring shape, and a plurality of pockets 32 for holding the balls 27 and 28 are arranged in the circumferential direction at an intermediate portion of the axial width. The windows are arranged side by side. A portion between the pockets 32 and 32 of the cages 19 and 20 is an inclined columnar partition wall 34, and a portion on the smaller diameter side and a portion on the larger diameter side of the pocket 32 have both inner and outer diameter surfaces. A small-diameter annular portion 30 and a large-diameter annular portion 31 are formed in a cylindrical surface shape. Both side surfaces of each partition wall 34 have a spherical shape corresponding to the outer diameters of the balls 27 and 28.

By the way, ceramic balls are used for the bearing balls 27 and 28. When ceramics are used as the rolling elements, a combination of different materials is used for the bearing steel inner ring 12 and outer ring 14, and since the specific gravity is smaller than that of the steel rolling elements, friction and wear inside the bearings. Is reduced. The type of ceramic constituting the balls 27 and 28 is not particularly limited. For example, silicon nitride (Si ₃ N ₄ ), zirconia (ZrO ₂ ), silicon carbide (SiC), alumina (Al ₂ O ₃ ) and the like are preferable. Can be used for In consideration of friction characteristics, workability, specific gravity, etc., silicon nitride is particularly desirable. Further, the forming method of the ceramic rolling element is not particularly limited, and any forming method such as normal pressure, pressurization, HIP or the like can be used. These ceramic rolling elements are primary molded by die molding or granulation molding, and the ball obtained by secondary molding by atmospheric pressure sintering, pressure sintering, HIP sintering, etc. is finished by lapping etc. To be a completed ball. Of these, the cheapest raw spheres can be obtained by granulation molding-atmospheric pressure sintering, but if higher performance is required, those subjected to HIP sintering or pressure sintering are desirable.

  The material of the cages 19 and 20 for holding the balls 27 and 28 is preferably a material in which a synthetic resin such as nylon, polyamide, polyacetal, phenol, polypropylene, polyphenylene sulfide or the like is reinforced with glass fiber or the like. What added glass fiber as a reinforcing material to the base material of (6-6 nylon) is preferable from the viewpoint of strength and friction performance.

  Next, FIG. 2 shows a differential device using the differential ball bearing device according to the present invention. This differential device includes a differential case 51, a differential reduction mechanism 52 disposed in the differential case 51, and a difference. A pinion gear 54 that meshes with the ring gear 53 of the dynamic reduction mechanism 52 and a pinion shaft 55 that supports the pinion gear 54 are provided, and the pinion shaft 55 is rotatably supported in the differential case 51 via bearings 56 and 57.

  The differential ball bearing devices shown in FIG. 1 are used for the bearings 56 and 57, respectively. One of the bearings 56 disposed on the pinion gear 54 side is in contact with the end portion 33 of the inner ring 12 of the bearing 56, that is, the end surface 12a, on the end surface 54a of the pinion gear 54 of the pinion shaft 55, and the end surface of the outer ring 14 on the side opposite to the pinion gear. 14 a is in pressure contact with a step surface 58 formed on the inner surface of the case 51.

  In the other bearing 57, the end portion 33 of the inner ring 12, that is, the end surface 12 a (the end surface on the opposite flange side) is pressed against the end edge 50 a of the pinion flange 50, and the end surface 14 a of the outer ring 14 on the pinion gear side is on the inner surface of the case 51. It is in pressure contact with the formed step surface 59. A sleeve 60 is interposed between the one bearing 56 and the inner ring 12 of the other bearing 57.

  In this case, a preload is applied to the bearings 56 and 57 via the pinion flange 50 by screwing the nut member 62 into the threaded portion 61 at the end of the pinion shaft 55.

  In the present invention, since the balls 27 and 28 are made of ceramics, the rolling surfaces of the balls 27 and 28 and the outer ring raceways 13a and 13a are compared with ball bearings using steel balls that have been generally used conventionally. It is possible to reduce the rolling friction that acts on the contact portion between 13b and the inner ring raceways 11a and 11b. That is, the inertia can be reduced to reduce the slip and the wear can be reduced. Further, since the ceramic balls 27 and 28 are brought into contact with the outer ring 14 and the inner ring 12 made of hard metal such as steel, they are in a contact state between different materials, and are in contact with each other as compared with a contact state between the same kind of metals. The frictional resistance at the part is reduced. At the same time, the ceramic balls 27 and 28 have a smaller amount of elastic deformation than the steel balls, so that the Hertzian contact ellipse present in the contact portion is reduced, and the frictional resistance can be reduced. As a result, the weight is reduced as compared with the conventional bearing, the contact area can be reduced, and the torque of the bearing can be reduced.

  The radius of curvature of the cross-sectional shape of the outer ring raceways 13a, 13b is set to 54% or more and less than 56% of the outer diameter of the balls 27, 28, and the radius of curvature of the cross-sectional shape of the inner ring raceways 11a, 11b is set to the balls 27, The outer diameter of 28 is 52.5% or more and less than 56%. That is, the radius of curvature of the cross-sectional shape of the inner ring raceways 11a and 11b is 52.5% or more, which is larger than that of the conventional structure (about 51 to 52% of the outer diameter of the ball), and the cross sections of the outer ring raceways 13a and 13b. The radius of curvature of the shape is the same as the conventional one. Moreover, the existing outer ring 14 can be used, and productivity can be improved and costs can be reduced.

  As a result, since the Hertzian contact ellipse present in the contact portion can be reduced, differential slip and the like can be reduced, and rotational torque can be reduced and the bearing life can be extended. If the radius of curvature of the cross-sectional shape of the inner ring raceways 11a, 11b is 56% or more of the outer diameter of the balls 27, 28, the maximum Hertz contact pressure at the contact ellipse portion becomes excessive, and the inner ring raceways 13a, 13b. It is disadvantageous in terms of acoustics and peeling life because it reduces the rolling fatigue life.

  As another embodiment, the radius of curvature of the cross-sectional shape of the outer ring raceways 13a and 13b is 53% or more and less than 55% of the outer diameter of the balls 27 and 28, and the cross-sectional shape of the inner ring raceways 11a and 11b. Can be 50.5% or more and less than 52% of the outer diameter of each of the balls 27 and 28. In this case, it is particularly desirable that the inner ring 12 has a ball diameter of 50.5% to 51.5% and the outer ring 14 has a ball diameter of 53% to 54%.

  Thus, since the contact surface stress can be reduced by setting the radius of curvature of the inner ring raceway surfaces 11a and 11b to 50.5% or more and less than 52% of the ball diameter, seizure can be prevented over a long period of time. Prevents roughing. Further, by setting the outer ring raceway surfaces 13a and 13b to 53% or more and less than 55%, the contact area can be reduced to reduce the differential slip, and the torque can be reduced and the life can be extended. In addition, when the curvature radius of the outer ring raceway surfaces 13a and 13b is larger than 55%, the axial rigidity is lowered.

  The cage is made of synthetic resin. As a result, the friction between the rolling element and the cage pocket is reduced as compared with the conventional steel (SPCC) cage, and the cage itself is also lightweight, so the rotational torque is reduced and heat is generated. And the generation of wear powder can be suppressed and the life can be extended. Further, heat generation inside the bearing during rapid acceleration / deceleration rotation, which is one of the causes of poor lubrication and seizure, can be suppressed. Furthermore, in the cage made of synthetic resin, generation of iron-based wear powder generated in the steel cage is suppressed, which is effective for extending the life of the bearing.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the ball groups 15 and 16 have two rows. It may be the above. Further, the number of balls 27 and 28 in the ball groups 15 and 16 can be arbitrarily changed, and the spherical diameter can be changed within the range described in the paragraphs 0033 and 0035.

It is sectional drawing of the tandem type | mold double row angular contact ball bearing which shows embodiment of this invention. It is sectional drawing of the differential apparatus which shows embodiment of this invention. It is sectional drawing of the conventional tandem type double row angular contact ball bearing. It is sectional drawing of the conventional differential apparatus.

Explanation of symbols

11a, 11b Raceway surface 12 Inner ring 13a, 13b Raceway surface 14 Outer ring 15, 16 Ball group 19, 20 Cage 27, 28 Ball 51 Differential case 52 Differential reduction mechanism 53 Ring gear 54 Pinion gear 55 Pinion shaft

Claims (4)

In a differential device comprising a differential case, a differential reduction mechanism disposed in the differential case, a pinion gear meshing with a ring gear of the differential reduction mechanism, and a pinion shaft that supports the pinion gear, the pinion shaft is connected to the differential case. A ball bearing device for a differential that is rotatably supported in the interior,
The ball bearing device includes an inner ring having a double row raceway surface, an outer ring having a double row raceway surface corresponding to the raceway surface of the inner ring, and different pitch circles between the raceway surfaces of each row of the inner ring and the outer ring. A tandem angular contact ball bearing device comprising a double row ball group interposed with a diameter and a cage for holding the balls of the ball group, wherein the ball is made of ceramics. Ball bearing device.   The radius of curvature of the cross-sectional shape of the outer ring raceway is 54% or more and less than 56% of the outer diameter of each ball, and the radius of curvature of the cross-sectional shape of the inner ring raceway is 52.5% or more and 56% of the outer diameter of each ball. The differential ball bearing device according to claim 1, wherein the differential ball bearing device is less.   The curvature radius of the cross-sectional shape of the outer ring raceway is 53% or more and less than 55% of the outer diameter of each ball, and the curvature radius of the cross-sectional shape of the inner ring raceway is 50.5% or more and 52% of the outer diameter of each ball. The differential ball bearing device according to claim 1, wherein the differential ball bearing device is less.   The differential ball bearing device according to claim 1, wherein the cage is made of a synthetic resin.

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