JP2008008374A - Wheel bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing device wherein a cage can store an increased number of rollers without lowering its rigidity while minimizing an increase of drag torque. <P>SOLUTION: In the wheel bearing device having double-row rolling elements, an inner ring 6 is axially fixed to a hub ring 1 with a caulked portion 1c formed by plastically deforming the end of a small diameter stepped portion 1b outward in the radial direction. The outer-side rolling elements out of the double-row rolling elements are balls 9, and the inner-side rolling elements are tapered rollers 10. The pitch circle diameter of the inner-side tapered roller 10 is not larger than the pitch circle diameter of the outer-side ball. A roller coefficient γ is >0.94, and the window pushing angle of a pocket is 55-90°. The cage 8 is formed of engineering plastic superior in mechanical strength, oil resistance and heat resistance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wheel bearing device that rotatably supports a wheel of an automobile or the like, and more particularly to a wheel bearing device that is reduced in weight and increased in rigidity.

  A wheel bearing device for supporting a wheel of an automobile is disposed between a knuckle constituting a suspension device and a hub to which the wheel is attached. This wheel bearing device has a structure called “first generation” in which wheel bearings composed of bearings having double-row raceway surfaces are fitted, or a vehicle body mounting flange or wheel mounting directly on the outer periphery of an outer member. A “second generation” structure with a flange, a “third generation” structure having a hub ring in which one inner raceway surface is directly formed on the outer periphery of the hub, or a hub ring and a constant velocity universal joint It is roughly classified into a “fourth generation” structure in which the inner raceway surface is directly formed on the outer periphery of the outer joint member.

  For relatively lightweight vehicles such as passenger cars, double-row angular contact ball bearings in which the rolling elements of the bearings are steel balls are used. FIG. 10 shows a wheel bearing device having a “second generation” structure using double-row balls 29. In the figure, 30 is a hub wheel, 31 is an outer member, and 32 is a pair of inner rings. FIG. 11 shows a wheel bearing device for a “third generation” structure using double-row balls 29. In this bearing device, there is only one inner ring 33 on the inner side, and the outer raceway surface 34 is formed directly on the hub ring 35.

In large SUV vehicles (sports multipurpose vehicles) and trucks, double-row tapered roller bearings whose rolling elements are tapered rollers are often used. FIG. 12 shows an example of a “second generation” structure wheel bearing device using a pair of tapered roller bearings on the left and right. In the figure, 40 is a hub wheel, 41 is an outer member attached to a knuckle, 41a is a double row outer conical raceway surface, 42 is a pair of left and right inner members, 42a is an inner conical raceway surface, and 43 is a double row. The tapered roller 44 is a cage. The tapered roller 43 is accommodated in the pocket P of the holder 44 as shown in FIGS. Window press angle theta ₂ of the pocket P is set to the normal 25 ° to 50 ° as in the conventional retainer 44 in FIG. 14. Here, the “window pushing angle” refers to an angle formed by the guide surface of the retainer column part that abuts the peripheral surface of one roller.

  Recently, in order to reduce the impact on the environment, it has been required to reduce the fuel consumption of automobiles and to reduce the weight of automobiles to achieve this. Wheel bearings are also required to be reduced in weight, and it is required to support the weight of automobiles with smaller and lighter bearings than before. In other words, it is required to support a larger vehicle weight with the bearing of the previous size.

  However, reducing the size of the bearing relative to the vehicle leads to 1) a reduction in the rolling life of the bearing and 2) a reduction in bearing rigidity. The reduction of maximum surface pressure is an effective solution to these two problems. In order to reduce the maximum surface pressure, the number of rollers is increased without reducing the roller diameter of the bearing, if the bearing size is changed or the bearing size is not changed. In order to increase the number of rollers without reducing the roller diameter, the pocket interval of the cage must be narrowed. For this purpose, it is necessary to increase the pitch circle of the cage and bring it closer to the outer member side as much as possible. .

As an example in which the cage 44 is brought into contact with the outer member inner diameter surface, for example, there is a tapered roller bearing described in Patent Document 1. This tapered roller bearing guides the cage by bringing the outer circumferential surface of the small-diameter side annular portion of the cage and the outer circumferential surface of the large-diameter side annular portion into sliding contact with the inner diameter surface of the outer member. Further, a recess for suppressing drag torque is formed in the outer diameter surface of the column portion of the cage, so that the non-contact state between the outer diameter surface of the column portion and the raceway surface of the outer member is maintained. The cage includes a small-diameter-side annular portion, a large-diameter-side annular portion, and a plurality of column portions in which recesses are formed on the outer-diameter surface by connecting the small-diameter-side annular portion and the large-diameter-side annular portion in the axial direction. . A plurality of pockets are provided between the pillars for accommodating the tapered rollers in a rollable manner. The small-diameter side annular portion is provided with a flange portion that extends integrally on the inner diameter side. The tapered roller bearing of Patent Document 1 can increase the roller filling rate as compared with the conventional type in which the cage and the outer member do not contact with each other, thereby preventing early breakage due to excessive surface pressure on the raceway surface. This is an advantageous structure.
JP 2003-28165 A

  In the tapered roller bearing described in Patent Document 1, since there is a recess in the retainer column part, the plate thickness is inevitably reduced, the rigidity of the retainer is reduced, and the retainer is deformed by stress during assembly of the bearing. Or the cage is deformed during the rotation of the bearing. If an attempt is made to increase the rigidity of the cage, the diameter of the cage increases, which may cause an increase in torque due to sliding contact at the outer member contact portion.

  Further, in the case of a wheel bearing device, a moment load is applied from the tire to the hub flange via the wheel during turning of the vehicle, so that a deviation (inclination) occurs between the shaft of the inner member and the outer member of the bearing. In addition, since the cage is also tilted with respect to the shaft, the cage is in strong contact with the outer member, and there is a possibility that the cage is greatly worn and the heat generation due to the large sliding resistance may occur. Further, since the cage comes into contact with the outer member due to the inclination of the shaft, there is a possibility that a force is applied between the outer members and the cage is damaged.

On the other hand, a conventional typical tapered roller bearing with a cage other than the tapered roller bearing described in Patent Document 1 avoids contact between the outer member and the cage, and secures the column width of the cage. In order to obtain a strong cage column strength and smooth rotation, the roller coefficient γ (roller filling rate) defined by the following equation is usually designed to be 0.94 or less.
Roller coefficient γ = (Z · DA) / (π · PCD)
Here, Z: Number of rollers, DA: Roller average diameter, PCD: Roller pitch circle diameter

  If an attempt is made to simply increase the roller filling rate while keeping the pocket size of the cage as it is, the columns of the cage become thin, and sufficient column strength cannot be ensured. It is desirable that a tapered roller bearing capable of increasing the number of rollers accommodated without reducing the cage rigidity and strength and further suppressing the increase in cage drag torque can be obtained.

  An object of the present invention is to provide a wheel bearing device that can increase the number of rollers accommodated without lowering the cage rigidity, and that can suppress an increase in drag torque as much as possible.

  In order to achieve the above object, the invention of claim 1 integrally includes an outer member having a double row outer raceway surface formed on the inner periphery, and a wheel mounting flange for mounting a wheel on one end. An inner ring comprising a hub ring having a small-diameter step portion formed therein, and at least one inner ring press-fitted into the small-diameter step portion of the hub ring and having an inner race surface facing the outer race surface of the double row on the outer periphery. In a wheel bearing device comprising a member and a double row rolling element that is rotatably accommodated between both raceway surfaces of the inner member and the outer member, the outer side of the double row rolling element The rolling element is a ball, the inner rolling element is a tapered roller, and the pitch circle diameter of the inner tapered roller is made equal to or smaller than the pitch circle diameter of the outer ball.

  In this way, the outer side rolling element of the double row rolling elements is a ball, the inner side rolling element is a tapered roller, and the pitch circle diameter of the inner side tapered roller is set to the pitch circle of the outer side ball. Since the diameter is less than or equal to the diameter, the rigidity of the inner rolling element row portion is increased, and the life is the same even if the load applied to the inner rolling element row portion is greater than the load applied to the outer rolling element row portion. Or more. Therefore, it is possible to provide a wheel bearing device that can realize a design without waste and has improved strength and durability.

  The invention of claim 2 is characterized in that, in the invention of claim 1, a pair of inner rings are press-fitted into the small-diameter step portion of the hub wheel, and the inner diameters of these inner rings are set to be the same.

  Thereby, the small diameter step part of a hub ring can be made into a straight shape, and workability can be improved. Further, by setting the inner diameters of the pair of inner rings, it is easy to set the preload applied to the inner tapered roller and the outer ball.

  According to a third aspect of the invention, in the first aspect of the invention, the outer raceway inner raceway surface is directly formed on the outer periphery of the hub wheel, and the inner diameter side from the inner raceway surface is formed with the small diameter step portion. The inner ring on the inner side is press-fitted into the small diameter step portion through a predetermined tightening allowance.

  This is called a third generation structure, and although it is a double row rolling element structure, one inner ring is reduced, and the number of parts is reduced and the cost can be reduced.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the inner tapered roller cage is made of an engineering plastic excellent in mechanical strength, oil resistance and heat resistance, and the pocket window of the cage is formed. The pushing angle is 55 ° or more and 90 ° or less, and the roller coefficient γ is more than 0.94.

  By using engineering plastic as a resin material for the cage, the cage weight is lighter, self-lubricating, and the coefficient of friction is smaller than that of steel plate cages. Combined with the effect of the lubricating oil, it is possible to suppress the occurrence of wear due to contact with the outer member. Since engineering plastics are lighter and have a smaller coefficient of friction than steel plates, they are suitable for reducing torque loss and cage wear when starting bearings.

  The window push angle is a maximum of about 50 ° for a tapered roller bearing with a cage in which the cage is spaced from the outer member. In the present invention, the roller coefficient γ can be made to exceed 0.94 by setting the window pushing angle to be larger.

  The reason why the lower limit window pushing angle is set to 55 ° or more is to ensure a good contact state with the roller, and when the window pushing angle is less than 55 °, the contact state with the roller is deteriorated. That is, in order to make γ> 0.94 after securing the cage strength, a good contact state cannot be secured unless the window pushing angle is 55 ° or more.

  Also, the upper limit window pushing angle is set to 90 ° or less because if it is further increased, the pressing force in the radial direction is increased, and there is a risk that smooth rotation cannot be obtained even with a self-lubricating resin material. It is.

  Engineering plastics include general purpose engineering plastics and super engineering plastics. Typical examples are listed below, but these are examples of engineering plastics, and engineering plastics are not limited to the following.

[General-purpose engineering plastics] Polycarbonate (PC), polyamide 6 (PA6), polyamide 66 (PA66), polyacetal (POM), modified polyphenylene ether (m-PPE), polybutylene terephthalate (PBT), GF reinforced polyethylene terephthalate (GF) -PET), ultra high molecular weight polyethylene (UHMW-PE)

[Super Engineering Plastics] Polysulfone (PSF), Polyethersulfone (PES), Polyphenylene sulfide (PPS), Polyarylate (PAR), Polyamideimide (PAI), Polyetherimide (PEI), Polyetheretherketone ( PEEK), liquid crystal polymer (LCP), thermoplastic polyimide (TPI), polybenzimidazole (PBI), polymethylbenten (TPX), poly 1,4-cyclohexanedimethylene terephthalate (PCT), polyamide 46 (PA46), polyamide 6T (PA6T), polyamide 9T (PA9T), polyamide 11,12 (PA11,12), fluororesin, polyphthalamide (PPA)

  It should be noted that a PA46 glass fiber (GF) reinforcing material may be used for a vehicle having a relatively large vehicle weight, and a PA66 GF reinforcing material may be used for a vehicle having a small vehicle weight.

  The wheel bearing device according to the present invention integrally includes an outer member having a double row outer raceway formed on the inner periphery, and a wheel mounting flange for mounting the wheel on one end, and a small-diameter stepped portion on the outer periphery. And an inner member comprising at least one inner ring press-fitted into a small-diameter step portion of the hub ring and formed with an inner raceway surface facing the outer raceway surface of the double row on the outer periphery, In the wheel bearing device including a double row rolling element that is slidably accommodated between both raceway surfaces of the inner member and the outer member, an outer side rolling element of the double row rolling element includes: It is a ball, and the inner side rolling element is a tapered roller, and the pitch diameter of the inner side tapered roller is made equal to or less than the pitch diameter of the outer side ball, so the rigidity of the inner side rolling element row is high. The rolling element row on the inner side Load applied to the minute can be the same or larger than even life is greater than the load applied to the rolling element string part of the outer side. Therefore, it is possible to provide a wheel bearing device that can realize a design without waste and has improved strength and durability.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing a first embodiment of a wheel bearing device according to the present invention. This wheel bearing device is for a driven wheel called the second generation, and includes a hub wheel 1 and a wheel bearing 2 fixed to the hub wheel 1. The hub wheel 1 integrally has a wheel mounting flange 3 for mounting a wheel (not shown) at one end portion on the outer side, and hub bolts 3a are implanted in the wheel mounting flange 3 in a circumferentially equal distribution. Yes.

  The wheel bearing 2 is formed by being press-fitted into the small diameter step portion 1b through a predetermined tightening margin while being abutted against the shoulder portion 1a of the hub wheel 1, and by plastically deforming an end portion of the small diameter step portion 1b. It is fixed in the axial direction by the caulking portion 1c. The hub wheel 1 is formed of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the surface hardness is hardened to a range of 58 to 64 HRC by induction hardening from the shoulder 1a to the small diameter step 1b. ing. The caulking portion 1c is kept in the surface hardness after forging. Thereby, it has sufficient mechanical strength with respect to the rotational bending load applied to the wheel mounting flange 3, and the fretting resistance of the small-diameter step portion 1b serving as the fitting portion of the wheel bearing 2 is improved. The plastic working of the caulking portion 1c can be smoothly performed while preventing generation of minute cracks and the like.

  The wheel bearing 2 integrally has a vehicle body mounting flange 4c to be attached to a knuckle (not shown) constituting a suspension device on the outer periphery, and double row outer raceway surfaces 4a and 4b are formed on the inner periphery. The outer member 4, two inner rings 5, 6 each having inner race surfaces 5a, 6a facing the outer race surfaces 4a, 4b in the double row on the outer periphery, and both race surfaces 4a, 5a and 4b, 6a. A plurality of balls 9 and tapered rollers 10 accommodated so as to be freely rollable via cages 7 and 8 are provided. Seals 11 and 12 are attached to the opening portion of the annular space formed between the outer member 4 and the two inner rings 5 and 6, leakage of grease sealed inside the bearing to the outside, and rainwater from the outside And dust are prevented from entering the bearing.

  The outer raceway surfaces 4 a and 5 a are formed in an arc shape that makes angular contact with the ball 9, and the inner raceway surfaces 4 b and 6 a are formed in a taper shape that makes line contact with the tapered roller 10. Then, a large flange 6b for guiding the tapered roller 10 on the large diameter side of the inner raceway surface 6a in the inner ring 6 on the inner side and a small flange 6c for preventing the tapered roller 10 from falling off are formed on the small diameter side. Yes.

  The outer member 4 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the double row outer raceway surfaces 4a and 4b are hardened to a surface hardness of 58 to 64 HRC by induction hardening. Has been processed. Further, the inner rings 5 and 6 and the balls 9 and the tapered rollers 10 are made of high carbon chrome steel such as SUJ2, and are hardened in the range of 58 to 64 HRC up to the core part by quenching.

  Here, in this embodiment, the pitch circle diameter PCD of the outer side ball 9 and the pitch circle diameter PCD of the inner side tapered roller 10 are set to be the same. Therefore, the rigidity of the inner side rolling element row portion is increased, the basic load rating is larger than the basic rated load of the outer side rolling element row portion, and the load applied to the inner side rolling element row portion is increased on the outer side. It becomes larger than the load added to a rolling element row | line | column part, and can make a lifetime the same or more. That is, it is possible to provide a wheel bearing device that can realize a design without waste and has improved strength and durability.

  FIG. 2 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention. This embodiment basically differs from the above-described embodiment only in the configuration of the hub wheel, and other parts having the same parts or the same functions are denoted by the same reference numerals and detailed description thereof is omitted. .

  This wheel bearing device is for a driven wheel called a third generation, and includes an outer member 4, a hub wheel 13, and an inner ring 6 press-fitted into a small-diameter step portion 13 b of the hub wheel 13. And a member 14. The hub wheel 13 has an outer side inner raceway surface 13a facing the outer side outer raceway surface 4a and a small-diameter step portion 13b extending in the axial direction from the inner raceway surface 13a. The inner ring 6 is press-fitted into the small-diameter step portion 13b through a predetermined tightening allowance, and is fixed in the axial direction by the crimping portion 13c.

  Seals 15 and 12 are attached to the opening portion of the annular space formed between the outer member 4 and the hub ring 13 and the inner ring 6, leakage of grease sealed inside the bearing to the outside, and rainwater from the outside. And dust are prevented from entering the bearing. The hub wheel 13 is formed of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and is surfaced by induction quenching from the seal land portion where the seal 15 is in sliding contact to the inner raceway surface 13a and the small diameter step portion 13b. Hardening is performed in the range of 58 to 64 HRC.

  Here, in the present embodiment, the pitch circle diameter PCD of the 9 outer rows of balls and the pitch circle diameter PCD of the 10 rows of tapered rollers on the inner side are set to be the same as in the embodiment described above. Therefore, while further reducing the weight and size of the device, the rigidity of the inner side rolling element row portion becomes higher, and the basic load rating becomes larger than the basic rated load of the outer side rolling element row portion. Even if the load applied to the rolling element row portion becomes larger than the load applied to the outer rolling element row portion, the service life can be the same or more.

  FIG. 3 is a longitudinal sectional view showing a third embodiment of the wheel bearing device according to the present invention. This embodiment is basically the same as the first embodiment (FIG. 1) described above, except that the pitch circle diameters of both rolling element rows are different, and the same parts or parts having the same function are the same. Reference numerals are assigned and detailed description is omitted.

  This wheel bearing device is for a driven wheel referred to as a second generation, and includes a hub wheel 16 and a wheel bearing 17 fixed to the hub wheel 16. The hub wheel 16 integrally has a wheel mounting flange 3 at an end portion on the outer side, and a small-diameter step portion 16b extending in the axial direction from the wheel mounting flange 3 via a shoulder portion 16a is formed. The wheel bearing 17 is press-fitted into the small diameter step portion 16b through a predetermined tightening margin while being abutted against the shoulder portion 16a of the hub wheel 16, and the end portion of the small diameter step portion 16b is plastically deformed. It is fixed in the axial direction by the formed caulking portion 16c.

  The wheel bearing 17 has a vehicle body mounting flange 4c integrally on its outer periphery, an outer member 18 having double-row outer raceway surfaces 18a, 18b formed on the inner periphery, and these double-row outer raceway surfaces 18a on the outer periphery. , 18b, a plurality of balls 9 and tapered rollers 10 which are accommodated so as to roll freely via cages 7 and 12 between inner raceway surfaces 19a and 20a. Seals 22 and 23 are attached to the openings of the annular space formed between the outer member 18 and the two inner rings 19 and 20, leakage of grease sealed inside the bearing to the outside, and rainwater from the outside And dust are prevented from entering the bearing.

  The outer member 18 is formed of medium carbon steel containing carbon of 0.40 to 0.80 wt% such as S53C, and the double row outer raceway surfaces 18a and 18b are hardened to a surface hardness of 58 to 64 HRC by induction hardening. Has been processed. Further, the inner rings 19 and 20 are made of high carbon chrome steel such as SUJ2, and are hardened in the range of 58 to 64 HRC to the core part by quenching.

  Here, in this embodiment, the pitch circle diameter PCDi of 10 rows of tapered rollers on the inner side is set smaller than the pitch circle diameter PCDo of 9 rows of balls on the outer side. As a result, the outer diameter D on the inner side of the outer member 18 can be set to a small diameter, the knuckle size can be reduced without reducing the basic load rating of the inner rolling element row, and the device is lighter and more compact. Can be achieved. Further, by increasing the thickness of the inner ring 19 on the outer side corresponding to the amount of expansion of the pitch circle diameter PCDo in the 9 rows of balls on the outer side, the hub wheel 16 can be used even if the pitch circle diameters PCDo and PDCi are different. The small-diameter step portion 16b can be formed in a straight shaft shape, and the workability can be improved.

  FIG. 4 is a longitudinal sectional view showing a fourth embodiment of the wheel bearing device according to the present invention. This embodiment is for a driven wheel called “third generation” structure, and includes a hub wheel 25 and a wheel bearing 17 fixed to the hub wheel 25. An outer raceway surface 25 a is directly formed on the outer diameter surface of the hub wheel 25. That is, the inner ring 19 of FIG. 3 is formed integrally with the hub ring 16. The inner ring 20 is fitted to the small diameter step portion 25 b of the hub ring 25. Similar to FIG. 3, the pitch circle diameter PCDi of the inner side tapered roller is smaller than the pitch circle diameter PCDo of the outer side ball.

  The hub wheel 25 integrally has a wheel mounting flange 3 at an end portion on the outer side, and a small diameter step portion 25b extending from the wheel mounting flange 3 in the axial direction via a shoulder portion 25d and an outer raceway surface 25a is formed. ing. The wheel bearing 17 is formed by being press-fitted into the small-diameter step portion 25b through a predetermined tightening margin while being abutted against the shoulder portion 25d of the hub wheel 25, and plastically deforming the end portion of the small-diameter step portion 25b. It is fixed in the axial direction by the caulking portion 25c.

  The wheel bearing 17 has a vehicle body mounting flange 4c integrally on its outer periphery, an outer member 18 having double-row outer raceway surfaces 18a, 18b formed on the inner periphery, and these double-row outer raceway surfaces 18a on the outer periphery. , 18b, and a plurality of balls 9 and tapered rollers 10 which are accommodated so as to roll freely through cages 7 and 12 between inner raceway surfaces 25a and 20a. Seals 22 and 23 are attached to the opening of the annular space formed between the outer member 18 and the hub wheel shoulder 25d and between the outer member 18 and the inner ring 20, and the grease sealed inside the bearing is exposed to the outside. And leakage of rainwater and dust from the outside is prevented.

  The outer member 18 is formed of medium carbon steel containing carbon 0.40 to 0.80 wt% such as S53C, and the double row outer raceway surfaces 18a and 18b are hardened to a surface hardness of 58 to 64 HRC by induction hardening. Has been processed. Further, the inner ring 20 is made of high carbon chrome steel such as SUJ2, and is hardened in the range of 58 to 64 HRC up to the core part by quenching.

  Here, in this embodiment, the pitch circle diameter PCDi of 10 rows of tapered rollers on the inner side is set smaller than the pitch circle diameter PCDo of 9 rows of balls on the outer side. As a result, the outer diameter D on the inner side of the outer member 18 can be set to a small diameter, the knuckle size can be reduced without reducing the basic load rating of the inner rolling element row, and the device is lighter and more compact. Can be achieved.

  FIG. 5 is a longitudinal sectional view showing a fifth embodiment of the wheel bearing device according to the present invention. In this embodiment, in order to increase the number of rollers without reducing the roller diameter, as shown in FIG. 6, the roller pitch circle is increased by moving the retainer 8 as close as possible to the outer member side. Others may be the same as those in the first to fourth embodiments. The cage 8 is integrally formed of engineering plastic such as PA46, PA66, PPS, PEEK, etc., and includes a small-diameter-side annular portion 8a, a large-diameter-side annular portion 8b, a small-diameter-side annular portion 8a, and a large-diameter side. And a plurality of column portions 8c that connect the annular portion 8b in the axial direction.

The window pressing angle Θ ₁ of the column surface 8d of the column portion 8c shown in FIG. 7 has a lower limit window pressing angle Θ ₁ min of 55 ° and an upper limit window pressing angle Θ ₁ max of 90 °. The window push angle is a maximum of about 50 ° for a tapered roller bearing with a cage in which the cage is spaced from the outer member. In the present invention, the roller coefficient γ can be made to exceed 0.94 by setting the window pushing angle to be larger. The reason why the lower limit window pushing angle Θ ₁ min is set to 55 ° or more is to ensure a good contact state with the roller, and when the window pushing angle is less than 55 °, the contact state with the roller is deteriorated. That is, in order to make γ> 0.94 after securing the cage strength, a good contact state cannot be secured unless the window pushing angle is 55 ° or more. The upper limit window push angle Θ ₁ max is set to 90 ° or less. If the upper limit window push angle Θ ₁ max is greater than 90 °, the pressing force in the radial direction increases, and there is a risk that smooth rotation cannot be obtained even with a self-lubricating resin material. This is because.

  A predetermined gap is formed between the column surface 8d of the pocket and the outer periphery of the tapered roller 10. The size of the gap is such that the tapered rollers 10 do not contact each other even if the tapered rollers 10 advance and retract in the circumferential direction as shown in FIG.

  As an example, the product of the present invention has a roller coefficient γ = 0.95 and the number of rollers Z = 25, while the conventional product has, for example, a roller coefficient γ = 0.88 and a number of rollers Z = 23. In the calculated value, the tapered roller bearing for a wheel of the present invention has a basic dynamic load rating C increased by 7% and a basic static load rating C0 increased by 9% compared to the conventional product. As the basic dynamic load rating and basic static load rating increase, the rolling life (calculated value) of the bearing is expected to increase by 20% as described in Example 1 below, and the bearing rigidity (calculated value) is expected to improve by 7%. It is.

9A and 9B show the results of the bearing life test and the bearing rigidity test of the present invention actually manufactured.
As a result of the bearing life test assuming severe running, the operating life of the product of the present invention (Example) was 3.2 times the calculated life of the conventional product.
Since the operating life of the conventional example was 2.3 times the calculated life of the conventional product, it was confirmed that the rolling life was extended (FIG. 9A).
As a result of the bearing rigidity test, it was confirmed that the product of the present invention was 7% more rigid than the conventional product (FIG. 9B).
The test is performed by measuring the displacement of the wheel mounting flange when the load load arm is fixed to the wheel mounting flange of the bearing and a load in the axial direction (simulating the moment load during cornering) is applied to the actual tire radial position. Converted into
The product of the present invention and the conventional product are the same except for the number of cages (use parts of the same shape), and the bearing preload is also equivalent.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Needless to say, the scope of the present invention is indicated by the description of the scope of claims, and includes the equivalent meanings of the scope of claims and all modifications within the scope. For example, in the wheel bearing device according to the present invention, the shape of the tapered roller bearing is not limited to the second generation type and the third generation type shown in the drawing, regardless of whether it is for driving wheels or driven wheels. The present invention can also be applied to a structure in which a member does not have a flange (first generation type) and a structure in which a raceway surface on the inner side is formed on the outer diameter of a constant velocity joint outer ring (fourth generation type). In the above embodiment, engineering plastics such as PA46, PA66, PPS, and PEEK are used as the cage material. However, if necessary, these resin materials or other engineering plastics may be made of glass fiber or What mix | blended carbon fiber etc. may be used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing a first embodiment of a wheel bearing device according to the present invention. The longitudinal cross-sectional view which shows 2nd Embodiment of the wheel bearing apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 3rd Embodiment of the wheel bearing apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 4th Embodiment of the wheel bearing apparatus which concerns on this invention. The longitudinal cross-sectional view which shows 5th Embodiment of the wheel bearing apparatus which concerns on this invention. The fragmentary sectional view of the tapered roller bearing used for the bearing device for wheels of the present invention. The partial expanded sectional view of the tapered roller bearing used for the wheel bearing apparatus of this invention. The partial expanded sectional view of the tapered roller bearing which shows the circumferential direction advance / retreat range of the tapered roller in a pocket. The figure which shows the result of the life test of a bearing. The figure which shows the result of the rigidity test of a bearing. The longitudinal cross-sectional view of the conventional ball bearing apparatus for 2nd generation wheels. The longitudinal cross-sectional view of the ball bearing apparatus for conventional 3rd generation wheels. The longitudinal cross-sectional view of the conventional tapered roller bearing apparatus for 2nd generation wheels. The fragmentary sectional view of the tapered roller bearing used for the conventional wheel bearing apparatus. The partial expanded sectional view of the tapered roller bearing used for the conventional wheel bearing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hub wheel 1a Shoulder part 1b Small diameter step part 1c Clamping part 2 Wheel bearing 3 Wheel mounting flange 3a Hub bolt 4 Outer member 4a, 4b Outer raceway surface 4c Car body installation flange 5, 6 Inner ring 5a, 6a Inner raceway surface 6b Large鍔 6c Small 鍔 7 Cage 8 Cage 8a Small-diameter side annular portion 8b Large-diameter side annular portion 8c Column portion 8d Column surface 9 Ball 11 Seal 13 Hub wheel 13a Inner raceway surface 13b Small-diameter step portion 13c Caulking portion 14 Inner member 15 Seal 16 Hub wheel 16a Shoulder portion 16b Small diameter step portion 16c Caulking portion 17 Wheel bearing 18 Outer member 18a Outer raceway surface 19 Inner ring 19a Inner raceway surface 20 Inner ring 22 Seal 25 Hub wheel 25a Raceway surface 25b Small diameter step portion 25c Addition Fastening portion 25d Shoulder portion 29 Ball 33 Inner ring 34 Track surface 35 Hub wheel 44 Cage

Claims (4)

An outer member having a double-row outer raceway surface formed on the inner periphery;
A hub wheel integrally having a wheel mounting flange for mounting a wheel at one end, a small-diameter step formed on the outer periphery, and a press-fitted into the small-diameter step of the hub wheel, and the outer circumferential surface of the double row on the outer periphery An inner member made of at least one inner ring formed with an inner raceway surface facing
In the wheel bearing device including the inner member and the double row rolling elements accommodated so as to be freely rollable between both raceway surfaces of the outer member,
Among the double row rolling elements, the outer side rolling element is a ball, the inner side rolling element is a tapered roller, and the pitch circle diameter of the inner side tapered roller is equal to or less than the pitch circle diameter of the outer side ball. A bearing device for a wheel, characterized in that   2. The wheel bearing device according to claim 1, wherein a pair of inner rings are press-fitted into the small-diameter step portion of the hub ring, and the inner diameters of these inner rings are set to be the same.   An outer raceway surface on the outer side is directly formed on the outer periphery of the hub wheel, and the small diameter step portion is formed on the inner side from the inner raceway surface. The wheel bearing device according to claim 1, wherein the inner ring is press-fitted.   The inner side tapered roller cage is made of engineering plastic with excellent mechanical strength, oil resistance and heat resistance, and the window push angle of the cage pocket is 55 ° or more and 90 ° or less. The wheel bearing device according to claim 1, wherein the coefficient γ exceeds 0.94.

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