Hub unit bearing

Abstract

The present invention provides a hub unit bearing equipped with a grease that is easy to seal and resistant to leakage, which reduces rotational torque and sliding torque. [Solution] The hub unit bearing is lubricated by grease sealed in the internal space between the inner surface of the outer ring member and the outer surface of the inner ring member. The grease includes a first grease sealed in the internal space between the rolling surfaces of the tapered rollers and the outer and inner ring raceways, and a second grease sealed on the larger diameter side than the first grease and having a lower consistency than the first grease.

Description

Technical Field

[0001] The present invention relates to a hub unit bearing.

Background Art

[0002] A hub unit bearing rotatably supports a vehicle wheel of an automobile with respect to a suspension device. As the hub unit bearing, for example, those using tapered rollers as rolling elements or those using balls are known.

[0003] In order to improve the fuel efficiency of an automobile, a hub unit bearing is required to have a low torque, and the structure inside the bearing and the lubricant enclosed therein are optimized. In the grease composition for a hub unit bearing described in Patent Document 1, the components of the base oil and the thickener contained therein are adjusted to provide a grease composition having a low torque and excellent compatibility with a sealing material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As indices representing the properties of grease, penetration and base oil kinematic viscosity are used. The penetration is determined by the type and blending amount of the thickener, and is an index representing the fluidity of the grease. That is, grease with a low penetration has low fluidity and is less likely to cause grease leakage. Further, grease with a low penetration increases the rotational torque of the rolling contact portion, but reduces the sliding torque of the sliding contact portion. On the other hand, grease with a high penetration has high fluidity and is easy to enclose inside the bearing. Further, grease with a high penetration is likely to reduce the rotational torque of the rolling contact portion, but increases the sliding torque of the sliding contact portion.

[0006] Base oil kinematic viscosity refers to the value obtained by dividing the absolute viscosity of the grease (base oil) by the density of the grease (base oil) under identical conditions (temperature and pressure). A higher base oil kinematic viscosity results in a thicker oil film formed on the lubricating surface, making it easier to exert lubrication for sliding contacts. On the other hand, a higher base oil kinematic viscosity increases rotational torque in areas where rolling contact occurs.

[0007] In hub unit bearings where the rolling elements are tapered rollers, the large flange portion and the large-diameter end face of the tapered roller make sliding contact, while the rolling surface of the tapered roller makes rolling contact with the outer and inner ring raceways. As a result, the required lubricant properties differ in each location. Specifically, in the area where the rolling surface of the tapered roller makes rolling contact with the outer and inner ring raceways, a reduction in rotational torque is particularly required, while in the area where the large flange portion and the large-diameter end face of the tapered roller make sliding contact, a reduction in sliding torque and improved seizure resistance are particularly required.

[0008] In hub unit bearings containing a grease composition as described in Patent Document 1, it was sometimes difficult to achieve both a reduction in rotational torque and sliding torque, as well as an improvement in sealing performance and leakage prevention performance.

[0009] The present invention has been made in view of the above problems, and its objective is to provide a hub unit bearing equipped with a grease that is easy to seal and does not leak easily, which reduces rotational torque and sliding torque in the hub unit bearing. [Means for solving the problem]

[0010] The above objective of the present invention is achieved by the following configuration. (1) An outer ring member having an outer ring raceway on its inner circumferential surface, An inner ring member having an inner ring raceway on its outer circumference and a large flange portion on the larger diameter side of the inner ring raceway, A plurality of tapered rollers are provided to roll freely between the outer ring raceway and the inner ring raceway, It is equipped with a grease sealed in the internal space between the inner circumferential surface of the outer ring member and the outer circumferential surface of the inner ring member, and is lubricated by grease. A hub unit bearing, The aforementioned grease is In the aforementioned internal space, a first grease is sealed between the rolling surface of the tapered roller and the outer ring raceway and the inner ring raceway. A second grease is sealed on the larger diameter side than the first grease and has a lower consistency than the first grease, including A hub unit bearing characterized by the following features. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a hub unit bearing equipped with grease that is easy to seal and resistant to leakage, which reduces rotational torque and sliding torque. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a partial cross-sectional view showing a hub unit bearing according to the first embodiment of the present invention. [Figure 2] Figure 2 is a magnified view of a portion of Figure 1. [Figure 3] Figure 3 is a schematic diagram illustrating the method of grease sealing. [Figure 4] Figure 4 is a diagram showing the hub unit bearing according to the second embodiment, with the same area as in Figure 2 but enlarged. [Figure 5] Figure 5 is a diagram showing an enlarged view of the same area as in Figure 2, relating to a modified example of the second embodiment of the hub unit bearing. [Figure 6] Figure 6 is an enlarged view of a combination seal according to a modified example of the second embodiment. [Modes for carrying out the invention]

[0013] (First Embodiment) Hereinafter, a first embodiment according to the present invention will be described based on the accompanying drawings. FIG. 1 is a half-sectional view showing a hub unit bearing according to the first embodiment of the present invention. FIG. 2 is a partial enlarged view of FIG. 1.

[0014] Regarding the hub unit bearing, the "axial direction" represents the direction in which the rotation axis O extends, which is the left-right direction in FIG. 1. Regarding the axial direction, the "outer side" refers to the left side of FIG. 1, which is the outer side in the vehicle body width direction in the assembled state to the vehicle. Conversely, the right side of FIG. 1, which is the central side in the vehicle body width direction, is referred to as the "inner side" regarding the axial direction. The "radial outer side" represents the direction away from the rotation axis O, which is the upper side in FIG. 1. The "radial inner side" represents the direction approaching the rotation axis O, which is the lower side in FIG. 1. The "circumferential direction" represents the direction of turning around the rotation axis O.

[0015] As shown in FIGS. 1 and 2, the hub unit bearing 1 of the present embodiment is for a driven wheel and mainly includes an outer ring member 2, an inner ring member 3, a plurality of tapered rollers 4, 4, a seal ring 5, and an encoder-equipped combined seal 6. <>

[0016] The outer ring member 2 has a stationary-side flange 7 on its outer peripheral surface and a double-row outer ring raceway 8a, 8b on its inner peripheral surface. In use, the outer ring member 2 is coupled and fixed to the knuckle of the suspension device by the stationary-side flange 7, and rotates while being supported by this suspension device.

[0017] The inner ring member 3 is composed of a hub ring 9 and an inner ring 10, and is arranged coaxially with the outer ring member 2 on the radially inner side of the outer ring member 2.

[0018] On the hub ring 9, a circular rotating-side flange 11 for supporting and fixing a braking rotating member such as a wheel and a disk rotor is provided on a portion protruding axially outward from the opening on the axially outer side of the outer ring member 2 and extending radially outward. Specifically, a plurality of insertion holes 11a are provided in the rotating-side flange 11. When each insertion hole 11a is a female thread, hub bolts (not shown) are respectively screwed therein. When each insertion hole 11a is a cylindrical hole, a stud bolt is serration-fitted therein.

[0019] Furthermore, the outer circumferential surface of the hub wheel 9 is provided with an inner ring raceway 12b of the axially outer row, in the portion facing the outer ring raceway 8b of the axially outer row of the outer ring member 2. Additionally, a small-diameter step portion 13 is provided at the axially inner end of the outer circumferential surface of the hub wheel 9, facing the outer ring raceway 8a of the axially inner row of the outer ring member 2. The outer circumferential surface of the hub wheel 9 also has a large flange portion 19, which is an axial side surface with a large flange surface 19a that can contact the large-diameter end face 4b of the axially outer row of tapered rollers 4. Furthermore, a sliding contact surface 16 is formed on the axially outer side of the large flange portion 19, against which the lip of the seal ring 5 slides.

[0020] The inner ring 10 is provided with an inner ring raceway 12a in the axial inner row on its outer circumferential surface. The inner ring 10 is fitted onto the outer circumferential surface of the small-diameter stepped portion 13 of the hub ring 9 by press-fitting with an overlap, with its axial outer end face abutting against the stepped surface 13a of the small-diameter stepped portion 13, and is fixed to the hub ring 9.

[0021] Furthermore, the inner ring 10 has small flange portions 15 that have axial sides that can closely face the small diameter end faces 4a, 4a of the double row of tapered rollers 4, 4. The inner ring 10 also has a large flange portion 14 that has a large flange surface 14a, which is an axial side that can contact the large diameter end face 4b of the axially inner row of tapered rollers 4.

[0022] Multiple tapered rollers 4, 4 are provided in the space between the outer ring raceway 8b and the inner ring raceway 12b of the axially outer row, and in the space between the outer ring raceway 8a and the inner ring raceway 12a of the axially inner row, respectively, with the smaller diameter end faces 4a, 4a of the tapered rollers 4, 4 of each row facing each other, and are held by a pair of cages 60, 60 so that they can roll freely.

[0023] Furthermore, an internal space 50 is formed between the inner circumferential surface of the outer ring member 2, including the outer ring raceways 8a and 8b, and the outer circumferential surface of the inner ring member 3 that faces the inner circumferential surface of the outer ring member 2. The outer circumferential surface of the inner ring member 3 that faces the inner circumferential surface of the outer ring member 2 includes the outer circumferential surface of the large flange portion 19 and the inner ring raceway 12b of the hub ring 9, and the outer circumferential surface of the small flange portion 15, the inner ring raceway 12a, and the outer circumferential surface of the large flange portion 14 of the inner ring 10. Grease G is sealed in the internal space 50 as a lubricant.

[0024] The seal ring 5 is supported and fixed to the axially outer end of the outer ring member 2, and is located between the inner circumferential surface of the outer ring member 2 and the sliding contact surface 16 axially outward from the large flange portion 19 of the hub ring 9, blocking the axially outer opening of the internal space 50 in which multiple tapered rollers 4, 4 are provided.

[0025] The encoder-equipped combination seal 6 is provided between the inner circumferential surface of the outer ring member 2 and the axially inner outer circumferential surface of the inner ring 10, and closes the axially inner opening of the internal space 50 in which a plurality of tapered rollers 4, 4 are provided. As shown in Figure 2, the encoder-equipped combination seal 6 comprises a seal ring 32 that is fitted and fixed to the axially inner end of the outer ring member 2, which is a stationary ring; a slinger 31 that is fitted and fixed to the axially inner end of the inner ring 10, which is a rotating ring; and an encoder 25 that is supported and fixed to the slinger 31.

[0026] The tapered rollers 4, cage 60, and grease G arranged in the internal space 50 of the hub unit bearing 1 will be described below. The tapered rollers 4, cage 60, and grease G are arranged approximately symmetrically in the internal space 50, in the internal space 50b located axially outward from the small flange portion 15, and in the internal space 50a located axially inward from the small flange portion 15. Therefore, since the internal space 50a and the internal space 50b have substantially the same structure, the internal space 50a will be described in detail below.

[0027] As shown in Figure 2, the retainer 60 comprises an annular small-diameter annular portion 61, an annular large-diameter annular portion 62 which is larger in diameter than the small-diameter annular portion 61, and a plurality of columnar portions 63 which are arranged at equal intervals in the circumferential direction and connect the small-diameter annular portion 61 and the large-diameter annular portion 62 in the axial direction. The small-diameter annular portion 61 is located on the smaller diameter side than the small-diameter end face 4a of the tapered roller 4, and the large-diameter annular portion 62 is located on the larger diameter side than the large-diameter end face 4b of the tapered roller 4. That is, the tapered roller 4 is housed in the space defined by the small-diameter annular portion 61, the large-diameter annular portion 62, and the circumferentially adjacent columnar portions 63 of the retainer 60.

[0028] Here, the large-diameter side in the internal space 50 refers to the direction from the large-diameter end face 4b toward the large flange portion 14 or large flange portion 19 in the rotation axis direction of the tapered roller 4. The small-diameter side refers to the direction from the small-diameter end face 4a toward the small flange portion 15 in the rotation axis direction of the tapered roller 4. More specifically, the large-diameter side in the internal space 50a refers to the direction from the large-diameter end face 4b toward the large flange portion 14 of the inner ring 10 in the rotation axis direction of the tapered roller 4, with respect to the tapered roller 4 arranged in the space between the outer ring raceway 8a and the inner ring raceway 12a of the axially inner row. The small-diameter side in the internal space 50a refers to the direction from the small-diameter end face 4a toward the small flange portion 15 in the rotation axis direction of the tapered roller 4, with respect to the tapered roller 4 arranged in the axially inner row. Furthermore, the large-diameter side in the internal space 50b refers to the direction from the large-diameter end face 4b toward the large flange portion 19 of the hub ring 9 in the direction of rotation of the tapered roller 4, with respect to the tapered roller 4 arranged in the space between the outer ring raceway 8b and the inner ring raceway 12b of the axially outer row. The small-diameter side in the internal space 50b refers to the direction from the small-diameter end face 4a toward the small flange portion 15 in the direction of rotation of the tapered roller 4, with respect to the tapered roller 4 arranged in the axially outer row.

[0029] In the internal space 50a, the grease G includes a first grease G1 sealed between the rolling surface of the tapered roller 4 and the outer ring raceway 8a and the inner ring raceway 12a, and a second grease G2 sealed on the larger diameter side of the internal space 50a than the first grease G1, and having a lower consistency than the first grease G1.

[0030] In this embodiment, the first grease G1 is sealed in the surrounding space near the large diameter end from the small diameter end to the large diameter end of the rolling surface of the tapered roller 4. That is, the first grease G1 is sealed in the region indicated by the dashed line A, which includes the space between the rolling surface of the tapered roller 4 and the outer ring raceway 8a and the inner ring raceway 12a, and the space between the rolling surface of the tapered roller 4 and the column portion 63 of the cage 60. Therefore, the first grease G1 contributes to the lubrication of the portion where the rolling surface of the tapered roller 4 and the outer ring raceway 8a and the inner ring raceway 12a roll in contact.

[0031] The second grease G2 is located on the larger diameter side in the internal space 50a than the first grease G1, and is situated near the large diameter end face 4b of the tapered roller 4. It is sealed in the region indicated by the dashed line B, which includes the space between the large diameter end face 4b of the tapered roller 4 and the large flange surface 14a. In other words, the second grease G2 contributes to lubrication of the portion where the large diameter end face 4b of the tapered roller 4 and the large flange surface 14a make sliding contact.

[0032] Furthermore, in the internal space 50b, the first grease G1 is sealed in the portion where the rolling surface of the tapered roller 4 makes rolling contact with the outer ring raceway 8b and the inner ring raceway 12b, and the second grease G2 is sealed on the larger diameter side than the first grease G1, in the portion where the large diameter end face 4b of the tapered roller 4 makes sliding contact with the large flange surface 19a.

[0033] The consistency of the second grease G2 is lower than that of the first grease G1. The consistency of the first grease G1 is in the range of consistency numbers 1 to 3 as defined in the Japanese Industrial Standard JIS K2220, and it is desirable that the consistency number of the second grease G2 be in the range of 3 to 4.

[0034] Furthermore, the kinematic viscosity of the base oil of the second grease G2 is higher than that of the base oil of the first grease G1. The kinematic viscosity of the base oil of the first grease G1 is 15 mm at 40°C. 2 / s~46mm 2 The range is / s, and the base oil kinematic viscosity of the second grease G2 is 68 mm at 40°C. 2 / s~220mm 2 It is desirable that the range be / s.

[0035] The following describes the method for sealing the first grease G1 and the second grease G2. Figure 3 is a schematic diagram showing the grease sealing method. As shown in Figure 3, first, a lubricant dispensing jig 100 is inserted into the opening between the inner circumferential surface of the outer ring member 2 and the outer circumferential surface of the inner ring member 3, and its tip is brought close to the retainer 60. Then, the first grease G1 is discharged from the discharge passage 100a of the lubricant dispensing jig 100 towards the internal space 50 via the retainer 60. Then, using a lubricant dispensing jig (not shown) of the same shape as the lubricant dispensing jig 100 used for sealing the first grease G1, the second grease G2 is discharged from the opening between the inner circumferential surface of the outer ring member 2 and the outer circumferential surface of the inner ring member 3 to the vicinity of the large diameter side end face 4b of the tapered roller 4.

[0036] The respective amounts of the first grease G1 and the second grease G2 are set according to the size of the tapered roller 4, the surface roughness of the outer ring member 2 and inner ring member 3, the shape of the retainer 60, and so on.

[0037] On the other hand, the total amount of the first grease G1 and the second grease G2 sealed in the internal space 50 is preferably set as follows. For example, if the volume of the static space is defined as the volume obtained by subtracting the volume of all of the double rows of tapered rollers 4,4 and the pair of cages 60,60 from the volume of the bearing internal space surrounded by the inner circumferential surface of the outer ring member 2, the outer circumferential surface of the inner ring member 3, and the back surface of the seal ring 5 and the combination seal 6 with encoder arranged in the opening, then the total amount of the first grease G1 and the second grease G2 sealed in the internal space 50 is set to be 20% or more and 50% or less of the volume of the static space.

[0038] In this embodiment, a first grease G1, which has high consistency and low base oil kinematic viscosity and is suitable for rolling contact, is sealed in the portion where the rolling surface of the tapered roller 4 makes rolling contact with the outer ring raceways 8a, 8b and inner ring raceways 12a, 12b. This reduces the rotational torque generated when the tapered roller 4 rolls. Furthermore, the first grease G1 has high fluidity and flows easily to the smaller diameter side of the tapered roller 4 when sealed through the opening of the internal space 50, making sealing easy. On the other hand, a second grease G2, which has low consistency and high base oil kinematic viscosity and is suitable for sliding contact, is sealed in the portion where the large diameter end face 4b of the tapered roller 4 makes sliding contact with the large flange faces 14a, 19a. This increases the oil film thickness between the large diameter end face 4b and the large flange faces 14a, 19a, reducing the sliding contact torque generated by friction during sliding contact. Furthermore, by placing the second grease G2, which has low fluidity, near the opening of the internal space 50, the grease is less likely to leak out.

[0039] (Second embodiment) The second embodiment will be described below with reference to the attached drawings. Note that some explanations of the same configuration as the first embodiment will be omitted. Figure 4 is a diagram showing an enlarged view of the hub unit bearing according to the second embodiment, covering the same area as in Figure 2.

[0040] The base oil, thickener, and additives contained in the first grease G1 according to this embodiment are the same as those contained in the second grease G2. In other words, the consistency is adjusted in the first grease G1 and the second grease G2 by changing the amount of thickener used.

[0041] As shown in Figure 4, the first grease G1 according to this embodiment is sealed in the space around the large-diameter end of the rolling surface of the tapered roller 4, starting from the small-diameter end. That is, the first grease G1 is sealed in the region indicated by the dashed line C, which includes the space between the rolling surface of the tapered roller 4 and the outer ring raceway 8a and the inner ring raceway 12a, the space between the rolling surface of the tapered roller 4 and the column portion 63 of the retainer 60, and the space between the large-diameter end face 4b and the large flange face 14a of the tapered roller 4.

[0042] The first grease G1 preferably has a consistency corresponding to a consistency number of 1 to 3 as specified in JIS K2220.

[0043] For the second grease G2, it is preferable to use so-called block grease with a consistency number of 4 to 6 as specified in JIS K2220. Block grease can be molded due to its low consistency. In this case, after the first grease G1 is sealed in, the annularly molded second grease G2 is placed near the large diameter side of the large diameter end face 4b of the tapered roller 4, between the outer circumferential surface of the large flange portion 14 and the inner circumferential surface of the outer ring member 2. The second grease G2 has a roughly U-shaped cross-section perpendicular to the circumferential direction and is arranged to surround the outer circumferential surface, inner circumferential surface, and axially inner end face of the large diameter annular portion 62. The second grease G2 is then close to or in contact with the large diameter end face 4b of the tapered roller 4 radially outside and radially inside the large diameter annular portion 62.

[0044] As described above, the second grease G2 is positioned on the larger diameter side of the larger diameter end face 4b of the tapered roller 4. In this embodiment, as will be described later, the thickener separated from the second grease G2 is mixed with the first grease G1. Therefore, the region indicated by the dashed line C, where the first grease G1 is sealed, includes a wider area extending to the larger diameter end of the rolling surface of the tapered roller 4 than the region indicated by the dashed line A in Figure 2.

[0045] As described above, by sealing in a first grease G1 and a second grease G2, which have the same base oil, thickener, and additives but with different amounts of thickener, the thickener contained in the second grease G2 gradually separates from the second grease G2 when the hub unit bearing 1 rotates, etc., and mixes with the first grease G1 near the large diameter end face 4b of the tapered roller 4. As a result, a grease with a low consistency is supplied to the sliding contact area between the large diameter end face 4b and the large flange surface 14a, reducing the sliding torque.

[0046] Generally, when several types of grease are sealed together, they gradually mix together. In this embodiment, because the additives may interact with each other, the base oil and thickener of the first grease G1 and the base oil and thickener of the second grease G2 consist of the same components. As a result, the thickener separated from the second grease G2 is less likely to diffuse, and the rate at which it mixes with the first grease becomes slower compared to when the components of the first grease G1 and the second grease G2 are different. Therefore, it becomes easier to maintain a difference in consistency between the sliding contact area and the rolling contact area.

[0047] The following describes modifications of the second embodiment. Figure 5 is a diagram showing an enlarged view of the hub unit bearing according to a modification of the second embodiment, covering the same area as in Figure 2. Figure 6 is a diagram showing an enlarged view of the combination seal according to a modification of the second embodiment.

[0048] As shown in Figure 5, in this example, the first grease G1 is sealed in the internal space 50a from the small-diameter end of the rolling surface of the tapered roller 4 to the space around the large-diameter end. That is, similar to Figure 4, the first grease is sealed in the area indicated by the dashed line C, which includes the space between the rolling surface of the tapered roller 4 and the outer ring raceway 8a and inner ring raceway 12a, between the rolling surface of the tapered roller 4 and the column portion 63 of the retainer 60, and the space between the large-diameter end face 4b of the tapered roller 4 and the large flange surface 14a. The second grease G2 is applied to the combination seal 26 provided between the outer circumferential surface of the large flange portion 14 and the inner circumferential surface of the outer ring member 2.

[0049] As shown in Figures 5 and 6, the combination seal 26 according to this embodiment includes a slinger 31 fitted onto the outer circumferential surface of the large flange portion 14, and a seal ring 32 fitted inside the outer ring member 2, which has seal lips (outer seal lip 41, intermediate seal lip 42, inner seal lip 43) that contact the slinger 31, and closes the opening of the internal space 50 that exists between the inner circumferential surface of the outer ring member 2 and the outer circumferential surface of the large flange portion 14.

[0050] The slinger 31 is manufactured by press-forming a metal sheet such as an austenitic stainless steel sheet like SUS304, a ferritic stainless steel sheet like SUS430, or a cold-rolled steel sheet (SPCC) that has been treated for rust prevention. It has an L-shaped cross-section and is annular in shape overall. The slinger 31 is externally fitted and fixed to the small-diameter stepped portion 13 of the inner ring 10.

[0051] The slinger 31 comprises a cylindrical fitting cylinder portion 33 that is fitted and fixed to the outer circumferential surface of the large flange portion 14 of the inner ring 10 by interference fit, and a ring-shaped ring portion 34 that is bent at approximately a right angle radially outward from the axially inner end of the fitting cylinder portion 33. Furthermore, if a magnetic steel plate is used as the material for the slinger 31, an encoder used to detect the rotational speed of the wheel can be attached to the axially inner surface of the ring portion 34.

[0052] As shown in Figure 6, the seal ring 32 comprises a core metal 35 and a sealing member 36.

[0053] The core metal 35 is made by press-forming a metal sheet such as cold-rolled steel sheet, and has a roughly L-shaped cross-section and is annular in shape overall. The core metal 35 comprises a cylindrical fixed cylinder portion 37 that is fitted and fixed to the axially inner end of the outer ring member 2, and an annular fixed ring portion 38 that is bent at roughly a right angle radially inward from the axially outer end of the fixed cylinder portion 37.

[0054] The sealing member 36 is made of an elastic material such as acrylonitrile butadiene rubber (NBR) and is fixed to the entire circumference of the surface of the core metal 35. The sealing member 36 is vulcanized using a vulcanizing mold and comprises an annular cover portion 39, a sealing base portion 40, an outer sealing lip 41, an intermediate sealing lip 42, and an inner sealing lip 43. Figure 6 shows the free-state shapes of the outer sealing lip 41, intermediate sealing lip 42, and inner sealing lip 43.

[0055] The annular covering portion 39 covers the entire inner circumferential surface of the fixed cylindrical portion 37.

[0056] The seal base 40 is fixed to the fixed ring portion 38 such that it covers the axial inner surface and the radially inner end of the fixed ring portion 38.

[0057] The outer seal lip 41 has its base end connected to the axially inner surface of the seal base 40, and is a side lip that extends radially outward as it moves axially inward. The tip of the outer seal lip 41 is in contact with the axially outer surface of the ring portion 34 that constitutes the slinger 31 over its entire circumference.

[0058] The intermediate seal lip 42 has its base end connected to the inner circumferential surface of the seal base 40 and is a dust lip that extends radially inward as it moves axially inward. The tip of the intermediate seal lip 42 is in contact with the axially inward portion of the outer circumferential surface of the fitting cylinder portion 33 that constitutes the slinger 31 over its entire circumference.

[0059] The inner seal lip 43 is positioned in contact with the internal space 50a. That is, the inner seal lip 43 is located axially outward from the outer seal lip 41 and the intermediate seal lip 42. Furthermore, the inner seal lip 43 extends inward towards the internal space 50a as it extends radially inward. In other words, the inner seal lip 43 is a grease lip whose base end is connected to the inner circumferential surface of the seal base 40, and which extends axially outward as it extends radially inward. The tip of the inner seal lip 43 slides against the axially outward portion of the outer circumferential surface of the fitting cylinder portion 33 that constitutes the slinger 31 over its entire circumference.

[0060] The tip of each of the outer seal lip 41, intermediate seal lip 42, and inner seal lip 43 is coated with a second grease G2. In this example, the second grease G2 acts as a sealing grease, lubricating the sliding contact between the tip of the outer seal lip 41, intermediate seal lip 42, and inner seal lip 43 and the slinger 31. The inner seal lip 43 extends radially inward towards the internal space 50a, and when the hub unit bearing 1 rotates, the second grease G2 applied between the inner seal lip 43 and the outer circumferential surface of the slinger 31 gradually flows into the internal space 50a. As a result, a low-concentration second grease G2 is gradually supplied between the large-diameter end face 4b of the tapered roller 4 and the large flange surface 14a, reducing the sliding torque at the sliding contact points. Furthermore, by creating a structure in which the second grease G2 is supplied gradually, the two types of grease are less likely to mix, and the difference in consistency is more easily maintained.

[0061] In the seal ring 5, which is positioned at the axially outer opening of the internal space 50 as shown in Figure 1, the second grease G2 may also be applied to the seal lip 44, which is provided in contact with the internal space 50b. The seal lip 44 slides against the sliding surface 16, which is the outer circumferential surface of the large flange portion 19, and extends radially inward towards the internal space 50b (axially inward). The second grease G2 applied between the seal lip 44 and the sliding surface 16 gradually flows into the internal space 50b. This makes it easier to maintain a difference in consistency between the rotational torque and the sliding torque in the internal space 50b.

[0062] It should be noted that the present invention is not limited to those exemplified in the above embodiments, and can be modified as appropriate without departing from the spirit of the invention. In particular, it is sufficient that grease G is sealed in the internal space 50 such that grease with properties suitable for the rolling contact portion and the sliding contact portion of the tapered roller 4 and the outer ring member 2 and inner ring member 3 are supplied. For example, in the first embodiment, the base oil contained in the first grease G1 and the base oil contained in the second grease G2 are different components, but the base oil and thickener contained in the first grease G1 and the base oil and thickener contained in the second grease G2 may be the same component. Also, in the second embodiment, the base oil and thickener contained in the first grease G1 and the base oil and thickener contained in the second grease G2 are the same component, but may be different components. Furthermore, grease G may be sealed in the axially inner internal space 50a and the axially outer internal space 50b by combining the above embodiments and their modified forms. For example, it is also possible to seal the same grease G as in the first embodiment in the internal space 50a and the same grease G as in the second embodiment in the internal space 50b.

[0063] As described above, the following matters are disclosed in this specification: (1) An outer ring member having an outer ring raceway on its inner circumferential surface, An inner ring member having an inner ring raceway on its outer circumference and a large flange portion on the larger diameter side of the inner ring raceway, A plurality of tapered rollers are provided to roll freely between the outer ring raceway and the inner ring raceway, It is equipped with a grease sealed in the internal space between the inner circumferential surface of the outer ring member and the outer circumferential surface of the inner ring member, and is lubricated by grease. A hub unit bearing, The aforementioned grease is In the aforementioned internal space, a first grease is sealed between the rolling surface of the tapered roller and the outer ring raceway and the inner ring raceway. A second grease is sealed on the larger diameter side than the first grease and has a lower consistency than the first grease, including A hub unit bearing characterized by the following features. With this configuration, by using high-consistency grease in the area where the rolling surface of the tapered roller makes rolling contact with the outer and inner ring raceways, rotational torque is reduced and grease sealing performance is improved. On the other hand, by supplying low-consistency grease to the area where the large flange and the large-diameter end face of the tapered roller make sliding contact, sliding contact torque is reduced. In addition, by positioning the low-consistency grease near the large-diameter end face of the tapered roller, grease leakage is prevented.

[0064] (2) The second grease is sealed between the large diameter end face of the tapered roller and the large flange surface of the large flange portion. The hub unit bearing according to (1), characterized in that This configuration allows for a reduction in sliding contact torque at the point where the large flange portion and the large-diameter end face of the tapered roller slide in contact.

[0065] (3) The kinematic viscosity of the base oil of the second grease is higher than that of the base oil of the first grease. A hub unit bearing according to (1) or (2), characterized in that it is a hub unit bearing according to (1) or (2). This configuration improves seizure resistance in the area where the large flange portion and the large-diameter end face of the tapered roller slide in contact, and reduces rotational torque in the area where the rolling surface of the tapered roller rolls into contact with the outer and inner ring raceways.

[0066] (4) The base oil and thickener contained in the first grease and the base oil and thickener contained in the second grease are the same component. A hub unit bearing according to (1) or (2), characterized in that it is a hub unit bearing according to (1) or (2). This configuration makes it difficult for the first grease and the second grease to mix, and makes it easier to maintain the difference in consistency.

[0067] (5) The second grease is formed into an annular shape and placed between the outer circumferential surface of the large flange and the inner circumferential surface of the outer ring member. A hub unit bearing according to any one of (1), (3), or (4), characterized in that... With this configuration, the second grease can be easily sealed into the outer row of the hub unit bearings as well.

[0068] (6) The outer ring member has a seal lip that contacts the outer surface of the large flange or the outer surface of a slinger fitted onto the outer surface of the large flange, and a seal ring fitted inside the outer ring member, The seal lip is provided at a position in contact with the internal space, and extends radially inward in the direction toward the internal space. The second grease is applied between the seal lip and the outer surface of the large flange or the outer surface of the slinger. A hub unit bearing according to any one of (1), (3), or (4), characterized in that... With this configuration, the second grease applied to the seal lip is supplied to the portion where the large flange and the large-diameter end face of the tapered roller slide in contact during the rotation of the hub unit bearing, thereby reducing the sliding torque and making it easier to maintain the difference in consistency between the first and second greases. [Explanation of Symbols]

[0069] 1 Hub unit bearing 2. Outer ring member 3. Inner ring member 4a Small diameter side end face 4b Large diameter side end face 5.32 Seal ring 6. Combination seals with encoders 7 Stationary flange 8a,8b Outer ring track 9 Hub Wheels 10 Inner Ring 11 Rotation side flange 11a Through hole 12a, 12b Inner ring track 13 Small diameter stepped section 13a Step surface 14,19 Otsubabe 14a Large Guard Surface 15 Small guard section 16 Sliding surface 25 encoders 26 combination stickers 31 Slinger 33 Fitting cylinder 34 Circular part 35 Mandrel 36. Sealing member 37 Fixed tube part 38 Fixed ring part 39 Annular covering 40 Seal base 41 Outer seal lip 42 Intermediate seal lip 43 Inner seal lip 50,50a,50b interior space 60 Retainer 61 Small diameter ring section 62 Large diameter annular section 63 Column section 100 Lubricant dispensing jig 100a discharge passage G1 First Grease G2 Second Grease

Claims

1. An outer ring member having an outer ring raceway on its inner circumferential surface, An inner ring member having an inner ring raceway on its outer circumference and a large flange portion on the larger diameter side of the inner ring raceway, A plurality of tapered rollers are provided to roll freely between the outer ring raceway and the inner ring raceway, It is equipped with a grease sealed in the internal space between the inner circumferential surface of the outer ring member and the outer circumferential surface of the inner ring member, and is lubricated by grease. A hub unit bearing, The aforementioned grease is In the aforementioned internal space, a first grease is sealed between the rolling surface of the tapered roller and the outer ring raceway and the inner ring raceway. A second grease is sealed on the larger diameter side than the first grease and has a lower consistency than the first grease, including A hub unit bearing characterized by the following features.

2. The second grease is sealed between the large-diameter end face of the tapered roller and the large flange surface of the large flange portion. A hub unit bearing according to claim 1, characterized in that...

3. The kinematic viscosity of the base oil of the second grease is higher than that of the base oil of the first grease. A hub unit bearing according to claim 1 or 2, characterized in that

4. The base oil and thickener contained in the first grease and the base oil and thickener contained in the second grease are the same component. A hub unit bearing according to claim 1, characterized in that...

5. The second grease is formed into an annular shape and is placed between the outer circumferential surface of the large flange and the inner circumferential surface of the outer ring member. A hub unit bearing according to claim 1 or 4, characterized in that

6. The outer ring member has a seal lip that contacts the outer circumferential surface of the large flange or the outer circumferential surface of a slinger fitted onto the outer circumferential surface of the large flange, and a seal ring fitted inside the outer ring member. The seal lip is provided at a position in contact with the internal space, and extends radially inward in the direction toward the internal space. The second grease is applied between the seal lip and the outer surface of the large flange or the outer surface of the slinger. A hub unit bearing according to claim 1 or 4, characterized in that

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