Bearing device and lubricant state detection method

Abstract

To provide a bearing device and a lubricant state detection method that can accurately grasp a state of a lubricant, and are superior in production cost and maintainability.SOLUTION: A bearing device comprises: an outer ring member which has an outer ring raceway surface on its inner peripheral surface; an inner ring member which has an inner ring raceway surface on its outer peripheral surface; a plurality of rolling bodies which are provided in a rollable state in a raceway between the outer ring raceway surface and inner ring raceway surface; a lubricant which is arranged in a bearing space between the inner peripheral surface of the outer ring member and the outer peripheral surface of the inner ring member; and a sensor which detects a state of the lubricant. The sensor has: a main body part which has a detection surface that the lubricant comes into contact with, and is made of translucent resin; a light-emitting body which is embedded in the main body part, and emits light toward the detection surface; and a light-receiving body which is embedded in the main body part, receives light reflected by a boundary surface between the detection surface and lubricant, and outputs a detection signal. The light-emitting body and the light-receiving body are embedded in the main body part such that optical axes cross each other on the detection surface, and also arranged radially outside the outer ring member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bearing device and a lubricant state detection method. [Background Art]

[0002] Patent Document 1 discloses a wheel bearing device comprising: an outer member having double-row raceways on an inner circumferential surface thereof; an inner member having a raceway facing the raceway of the outer member; and double-row rolling elements interposed between the opposing raceways of the outer member and the inner member, the wheel bearing device rotatably supporting a wheel relative to a vehicle body. This wheel bearing device comprises: a sensor, which is composed of a light-emitting element and a light-receiving element having mutually inclined angles on the inner circumferential surface of an outer ring, and determines the amount of foreign matter contained in a lubricant based on a change in reflected light of the lubricant; an IC tag provided on the outer circumferential surface of the outer ring and recording data from the sensor; and a communication means for the sensor and the IC tag, the communication means passing through a through hole of the outer ring, so as to determine deterioration of the lubricant.

[0003] However, in the bearing device of Patent Document 1, the optical axes of the light-emitting element and the light-receiving element cannot intersect on the grease surface, so the light received by the light-receiving element is diffuse reflected light. Therefore, the amount of light received by the light-receiving element is affected by disturbances such as the surface position of the lubricant, which weakens the correlation between the amount of light received by the light-receiving element and the degree of grease deterioration, making it difficult to improve the detection accuracy of the sensor. Furthermore, it is difficult to accurately mount and wire the light-emitting element and the light-receiving element on the inner circumferential surface of the outer member, and to perform replacement work in case of failure. Furthermore, since general-purpose light-emitting elements, light-receiving elements, and controllers thereof are not small enough to be built into the space inside a bearing, it is necessary to manufacture custom-made products. However, considering the production volume per part number of a conventional bearing device (for example, thousands to tens of thousands of pieces per month), manufacturing custom-made products results in high costs. [Prior Art Document] [Patent Document]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2007-256040 [Summary of the Invention] [Problems that the invention aims to solve]

[0005] Therefore, the present invention aims to provide a bearing device and a lubricant state detection method that can accurately grasp the state of the lubricant and are excellent in terms of manufacturing cost and maintainability. [Means for solving the problem]

[0006] The present invention consists of the following configuration. (1) An outer ring member having an outer ring raceway surface on its inner circumferential surface, An inner ring member having an inner ring raceway surface on its outer circumferential surface, A plurality of rolling elements are provided to be rotatable in the raceway between the outer ring raceway surface and the inner ring raceway surface, A lubricant disposed in the bearing space between the inner circumferential surface of the outer ring member and the outer circumferential surface of the inner ring member, A sensor for detecting the state of the lubricant, A bearing device comprising, The aforementioned sensor is A main body made of a translucent resin having a detection surface in contact with the lubricant, A light-emitting element embedded in the main body and irradiating light toward the detection surface, A light-receiving element embedded in the main body receives light reflected at the interface between the detection surface and the lubricant and outputs a detection signal, It has, The light-emitting element and the light-receiving element are embedded in the main body so that their optical axes intersect at the detection surface, and are positioned radially outward of the outer ring member. Bearing device. (2) The outer ring member has a through hole that penetrates radially from the inner circumferential surface to the outer circumferential surface of the outer ring member, The main body of the sensor has a radially inner portion and a radially outer portion that are connected to each other. The radially inner portion has the detection surface and is inserted into the through hole. The radially outer portion is in which the light-emitting element and the light-receiving element are embedded and arranged on the outer circumferential surface of the outer ring member. (1) The bearing device described above. (3) The sensor is positioned at the axial end of the outer ring member, The main body of the sensor has a radially inner portion and a radially outer portion that are connected to each other. The radially inner portion is fitted into the inner circumferential surface of the axial end of the outer ring member and extends axially outward from the outer ring member. The radially outer portion extends radially outward from the axially outer end of the radially inner portion, and the light-emitting body and the light-receiving body are embedded within it. (1) The bearing device described above. (4) A sealing member is provided between the inner circumferential surface of the sensor and the inner ring member to seal the bearing space. (3) The bearing device described above. (5) The main body of the sensor has a mirror embedded between the light-emitting element, the light-receiving element, and the detection surface that changes the direction of the optical axis. (1) The bearing device described above. (6) The main body of the sensor has a chamfer formed between the light-emitting element, the light-receiving element, and the detection surface. The aforementioned chamfer is a mirror surface that changes the direction of the optical axis. (1) The bearing device described above. (7) A method for detecting the lubricant state in a bearing device as described in any one of (1) to (6), The light source of the sensor is used to emit light, Based on the detection signal from the light receiver of the sensor, the amount of reflected light from the light emitter reflected at the interface between the detection surface and the lubricant is detected. Based on the amount of light, the deterioration state of the lubricant is determined. A method for detecting the state of lubricant. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a bearing device and a lubricant state detection method that can accurately grasp the state of the lubricant and have excellent manufacturing costs and maintainability. [Brief explanation of the drawing]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of the bearing device according to the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view of the bearing device according to Modified Example 1-1 of the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view of the bearing device according to Modified Example 1-2 of the first embodiment. [Figure 5] FIG. 5 is a cross-sectional view of the bearing device according to the second embodiment. [Figure 6] FIG. 6 is an enlarged cross-sectional view of section VI in FIG. 5. [Figure 7] FIG. 7 is a view showing a state where the bearing device according to the second embodiment is attached to a knuckle. [Figure 8] FIG. 8 is a view for explaining a modified example of the through hole of the outer ring. [Figure 9] FIG. 9 is an enlarged cross-sectional view of a portion corresponding to FIG. 6 in the bearing device according to Modified Example 2-1. [Figure 10] FIG. 10 is a cross-sectional view taken along line X-X in FIG. 9. [Figure 11] FIG. 11 is a cross-sectional view of the bearing device according to Modified Example 2-2 of the second embodiment. [Figure 12] FIG. 12 is a cross-sectional view of the bearing device according to Modified Example 2-3 of the second embodiment. [Figure 13] FIG. 13 is a cross-sectional view of the bearing device according to Modified Example 2-4 of the second embodiment. [Figure 14] FIG. 14 is a cross-sectional view of the bearing device according to Modified Example 2-5 of the second embodiment. [Figure 15] FIG. 15 is a cross-sectional view of the bearing device according to Modified Example 2-6 of the second embodiment. [Figure 16] FIG. 16 is a cross-sectional view of the bearing device according to the third embodiment. [Figure 17] FIG. 17 is a radial view of a lubricant deterioration detection window member fitted into an observation through hole 111, when the shape of the observation through hole as viewed from the radial direction is a round hole. [Figure 18] Figure 18 shows a view of the lubricant degradation detection window material fitted into the observation through-hole, when the shape of the observation through-hole is an elongated hole shape that is longer in the axial direction, as viewed from the radial direction. [Modes for carrying out the invention]

[0009] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

[0010] (First Embodiment) Figure 1 is a cross-sectional view of the bearing device 100 according to the first embodiment. Figure 2 is a cross-sectional view along line II-II in Figure 1. As shown in Figure 1, the bearing device 100 according to the first embodiment is a third-generation hub unit bearing and is used for driven wheels. The left side of Figure 1, which is on the outside in the width direction of the vehicle body when assembled to an automobile, is referred to as the "outboard side". Conversely, the right side of Figure 1, which is on the center side in the width direction of the vehicle body, is referred to as the "inboard side". "Axial direction" refers to the direction in which the rotation axis O of the bearing device extends, and is the left-right direction in Figure 1. "Radially outward" refers to the direction away from the rotation axis O, and is both the up-down sides in Figure 1. "Radially inward" and "radially center side" refer to the direction approaching the rotation axis O, and are the center side in the up-down direction in Figure 1. "Circumferential direction" refers to the direction of rotation around the rotation axis O.

[0011] The bearing device 100, consisting of this hub unit bearing, comprises an outer ring (outer ring member) 102 having a pair of outer ring raceway surfaces 101, 101 on its inner circumferential surface, an inner ring member 104 having a pair of inner ring raceway surfaces 103, 103 on its outer circumferential surface, a plurality of balls (rolling elements) 105 rotatably mounted in the respective raceways between the pair of outer ring raceway surfaces 101, 101 and the pair of inner ring raceway surfaces 103, 103, a pair of cages 106, 106 that hold the plurality of balls 105 at approximately equal intervals in the circumferential direction, and a pair of seals (sealing members) 107, 107a. As shown in Figure 2, a lubricant G is placed in the bearing space S between the inner circumferential surface of the outer ring 102 and the outer circumferential surface of the inner ring member 104. The bearing space S is sealed by a pair of seals (sealing members) 107, 107a on both axial sides, preventing the lubricant G from flowing out to the outside. As will be described in detail later, the bearing device 100 is equipped with a sensor 10 that detects the state of the lubricant G.

[0012] The inner ring member 104 includes a hub ring 104e and an inner ring 104a fitted onto a small-diameter stepped portion 104d formed on the hub ring 104e. The inner ring 104a has an inner ring raceway surface 103 on its outer circumference. This bearing device 100 is a crimp-type hub unit bearing assembled by crimping the inner ring 104a into the small-diameter stepped portion 104d of the hub ring 104e. Alternatively, the bearing device 100 may be a nut-fastened type hub unit bearing assembled by fastening a nut with the inner ring 104a fitted onto the small-diameter stepped portion 104d of the hub ring 104e. Furthermore, the bearing device 100 may be a hub unit bearing for a drive wheel, with a spline hole for engaging with a CVJ (constant velocity joint) provided in the center of the hub ring 104e.

[0013] A flange portion 102b is formed on the inboard side of the outer circumferential surface of the outer ring 102, projecting radially outward. Multiple holes 102c are formed in this flange portion 102b, penetrating in the axial direction. Bolts (not shown) for fixing the suspension device to the mounting part are inserted through, for example, the holes 102c in the flange portion 102b.

[0014] On the outboard side of the outer circumferential surface of the hub wheel 104e, another flange portion 104b is formed that protrudes radially outward. Multiple holes 104c are formed in this flange portion 104b at equal intervals in the circumferential direction, penetrating in the axial direction. Bolts 110 for fixing the wheel and brake rotor are inserted through, for example, the holes 104c in the flange portion 104b.

[0015] Alternatively, female threads may be formed in these holes 102c and 104c and bolts on the mounting side may be fastened, or stud bolts may be pre-installed in the holes 102c and 104c.

[0016] Multiple balls 105 in each row are held rotatably in the pockets of the holder 106.

[0017] A combination seal 107a and a seal 107 are provided between the inner circumferential surfaces of the pair of overhangs 102a, 102a at both axial ends of the outer ring 102 and the outer circumferential surfaces of the inner ring 104a and the hub ring 104e, respectively, thereby sealing the bearing space S.

[0018] The outer ring 102 has a through hole 108 that extends radially from the inner circumferential surface to the outer circumferential surface of the outer ring 102. The through hole 108 is located between a pair of outer ring raceway surfaces 101, 101 in the axial direction. The through hole 108 has a cylindrical shape that extends radially. As described later, the radially inner portion 23 of the sensor 10 is inserted into and fixed in the through hole 108.

[0019] As shown in Figures 1 and 2, the sensor 10 has a main body 20 made of translucent resin having a detection surface 21 that comes into contact with the lubricant G, and a sensor unit 30 that detects the state of the lubricant G adhering to the detection surface 21. The sensor 10 is inserted from the radially outside into the through hole 108 of the outer ring 102 so that the detection surface 21 faces the radially inner bearing space S, and detects the state of the lubricant G in the bearing space S.

[0020] The sensor 10 is provided at least one location in the circumferential direction of the outer ring 102. The sensor 10 may be provided at multiple locations in the circumferential direction of the outer ring 102. However, considering that the lubricant G is agitated and flows by the ball 105, providing the sensor at only one location in the circumferential direction of the outer ring 102 is sufficient to obtain the function of detecting the state of the lubricant G.

[0021] The main body portion 20 is preferably formed from a resin material that has high transparency and excellent heat resistance, such as acrylic or polycarbonate. The main body portion 20 has a radially inner portion 23 and a radially outer portion 25 that are connected to each other in the radial direction.

[0022] The radially inner portion 23 of the main body 20 is cylindrical in shape and extends radially, and has a detection surface 21 at its radially inner end. In this embodiment, the radially inner portion 23 is substantially the same shape as the through hole 108 of the outer ring 102. When the radially inner portion 23 is inserted into the through hole 108, the outer circumferential surface and both radial end faces of the radially inner portion 23 are positioned to substantially coincide with the inner circumferential surface and the openings at both radial ends of the through hole 108. In other words, the radially inner portion 23 is inserted into the through hole 108 without any gaps.

[0023] The radially outer portion 25 of the main body 20 is connected to the radially outer end of the radially inner portion 23 and is integrally formed with the radially inner portion 23. The radially outer portion 25 is, for example, a cylindrical shape with a larger diameter than the radially inner portion 23. Therefore, the radially outer portion 25 protrudes more from the radially inner portion 23 on both axial sides (see Figure 1) and also protrudes more from the circumferential direction (see Figure 2).

[0024] The radially outer portion 25 has the light-emitting element 31 and the light-receiving element 33 of the sensor portion 30 embedded in it and is positioned on the outer circumferential surface of the outer ring 102. In this embodiment, as shown in Figure 2, a seating surface 109 that protrudes radially outward is formed on the outer circumferential surface of the outer ring 102, and the radially outer portion 25 is placed on this seating surface 109. Therefore, the light-emitting element 31 and the light-receiving element 33 embedded in the radially outer portion 25 are positioned radially outward of the outer ring 102.

[0025] The sensor unit 30 includes a light-emitting element 31 such as a light-emitting diode (LED) and a light-receiving element 33 such as an illuminance sensor. These light-emitting element 31 and light-receiving element 33 are embedded in the radially outer portion 25 of the main body 20 so as to be spaced apart from each other in the circumferential direction.

[0026] The sensor 10 has a detection surface 21 on the radially inner surface (the surface on the bearing space S side) of the radially inner portion 23. The sensor 10 detects the state of the lubricant G adhering to the detection surface 21 using the sensor unit 30. As described above, the radially inner portion 23 of this embodiment has substantially the same shape as the through hole 108 of the outer ring 102, so the detection surface 21 of the radially inner portion 23 is positioned substantially at the same location as the radially inner opening 108a of the through hole 108 of the outer ring 102, and therefore its radial position substantially coincides with (is flush with) the inner circumferential surface of the outer ring 102.

[0027] As shown in Figure 2, the light-emitting element 31 and the light-receiving element 33 are arranged so that, when viewed from the axial direction of the sensor 10, their respective optical axes 31a and 33a are inclined to gradually approach the detection surface 21. As a result, with respect to the axial direction of the sensor 10 (the vertical direction in Figure 2; the radial direction of the bearing device 100), the optical axis 31a of the light-emitting element 31 is inclined at an inclination angle α, and the optical axis 33a of the light-receiving element 33 is inclined at an inclination angle β. These optical axes 31a and 33a of the light-emitting element 31 and the light-receiving element 33 intersect at the detection surface 21. The inclination angles α of the optical axis 31a of the light-emitting element 31 and β of the optical axis 33a of the light-receiving element 33 are in the range of 0° to 20°, respectively. Preferably, the inclination angles α of the optical axis 31a of the light-emitting element 31 and β of the optical axis 33a of the light-receiving element 33 are in the range of 5° to 15° and are the same angle (α=β).

[0028] In the sensor unit 30, the light emitter 31 illuminates the lubricant G adhering to the detection surface 21 with light. When the light reflected at the interface between the detection surface 21 and the lubricant G is received by the light receiver 33, the light receiver 33 converts the received light into an electrical signal and outputs it as a detection signal.

[0029] The light-emitting element 31 and light-receiving element 33 that constitute the sensor unit 30 transmit and receive signals to and from a detection device (not shown) by wire or wireless means. In the case of wireless communication, communication with the detection device is done via a transmitter or the like. When the bearing device 100 is used with the outer ring 102 on which the sensor 10 is mounted as a stationary ring, a wired communication method can be used to reduce costs. On the other hand, when the bearing device 100 is used with the outer ring 102 on which the sensor 10 is mounted as a rotating ring, a wireless communication method can be used to communicate smoothly with the rotating sensor unit 30.

[0030] The detection device emits light from the light emitter 31 and receives a detection signal from the light receiver 33. Based on the voltage of the detection signal, the device monitors the state of the lubricant G using the color (brightness) of the lubricant G as a parameter.

[0031] Here, the lubricant G changes color from its initial state (color of the coloring agent) due to oxidation of the base oil, consumption of additives, deterioration due to the incorporation of wear materials generated by contact between the outer ring raceway surface 101 and the inner ring raceway surface 103 and the ball 105. For example, lubricant G, which is brown in its initial state, changes to black as it deteriorates, thus reducing its brightness. As a result, the amount of light that reaches the photodetector 33 after being reflected at the interface between the light emitter 31 and the lubricant G decreases. The illuminance of the reflected light reaching the photodetector 33 is proportional to, for example, the voltage of the detection signal from the photodetector 33. Therefore, when the illuminance of the reflected light reaching the photodetector 33 decreases, the voltage of the detection signal output from the photodetector 33 decreases.

[0032] The detection device then determines that the lubricant G has deteriorated based on the detection signal from the photodetector 33 when the amount of light at the photodetector 33 decreases and the voltage of the detection signal falls below a preset threshold. For example, the detection device determines that the deterioration state of the lubricant G is a state requiring attention, a state requiring replacement, or a state where the lifespan has been reached.

[0033] Thus, according to the bearing device 100 of the first embodiment, the amount of reflected light irradiated from the light-emitting body 31 and reflected at the interface between the detection surface 21 and the lubricant G is detected based on the detection signal from the light-receiving body 33. Therefore, it is less susceptible to external disturbances and can accurately grasp the state of the lubricant G adhering to the detection surface 21. Furthermore, the light-emitting element 31 and the light-receiving element 33 are embedded in the main body 20 so that their optical axes 31a and 33a intersect on the detection surface 21, and are positioned radially outward of the outer ring 102. Therefore, compared to the case where the light-emitting element and the light-receiving element are provided on the inner circumferential surface of the outer member, as in Patent Document 1, mounting accuracy can be improved, and wiring work and replacement in case of failure can be made easier. Furthermore, since the light-emitting element 31 and the light-receiving element 33 are positioned radially outward of the outer ring 102, even large, general-purpose components can be positioned without problems, eliminating the need for custom-made components and thus reducing the cost of the sensor 10.

[0034] Furthermore, the outer ring 102 has a through hole 108 that penetrates radially from the inner circumferential surface to the outer circumferential surface of the outer ring 102, and the main body 20 of the sensor 10 has a radially inner portion 23 and a radially outer portion 25 that are connected to each other, the radially inner portion 23 has a detection surface 21 and is inserted into the through hole 108, and the radially outer portion 25 has a light-emitting body 31 and a light-receiving body 33 embedded in it and is arranged on the outer circumferential surface of the outer ring 102. Therefore, by inserting the radially inner portion 23 into the through hole 108, the sensor 10 can be easily and accurately fixed to the bearing device 100.

[0035] (Extreme variation 1-1) Next, a modified example 1-1 of the first embodiment will be described. Note that components identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted. Figure 3 is a cross-sectional view of the bearing device 100 according to modified example 1-1 of the first embodiment.

[0036] In the first embodiment described above, the radial position of the detection surface 21 provided on the radially inner portion 23 of the main body 20 of the sensor 10 substantially coincided with the radial position of the inner circumferential surface of the outer ring 102 (see Figures 1 and 2). However, as shown in Figure 3, the radially inner portion 23 of the main body 20 of the sensor 10 may extend radially inward from the inner circumferential surface of the outer ring 102. In this case, the sensor 10 can determine the degree of deterioration of the lubricant G near the hub ring 104e.

[0037] (Variations 1-2) Next, a modified example 1-2 of the first embodiment will be described. Note that components identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted. Figure 4 is a cross-sectional view of the bearing device 100 according to modified example 1-2 of the first embodiment.

[0038] In the first embodiment described above, the light-emitting element 31 and the light-receiving element 33 were spaced apart from each other in the circumferential direction (see Figure 2). However, as shown in Figure 4, the light-emitting element 31 and the light-receiving element 33 may be spaced apart from each other in the axial direction. In this case, the light-emitting element 31 and the light-receiving element 33 are arranged in such a way that, when viewed from the circumferential direction of the sensor 10, their respective optical axes 31a and 33a are inclined to gradually approach the detection surface 21.

[0039] (Second Embodiment) Figure 5 is a cross-sectional view of the bearing device 200 according to the second embodiment. Figure 6 is an enlarged cross-sectional view of part VI in Figure 5. As shown in Figures 5 and 6, the bearing device 200 according to the second embodiment is a hub unit bearing of a first-generation structure in which a double-row tapered roller bearing is fitted between the knuckle and the hub ring that constitute the suspension device.

[0040] In the second embodiment and its modified form, "axially inward" refers to the direction in which the pair of outer ring raceway surfaces 231 or the pair of inner ring raceway surfaces 241 move closer together (the center side in the left-right direction of Figure 5; the left side in Figure 6), and "axially outward" refers to the direction in which the pair of outer ring raceway surfaces 231, 231 or the pair of inner ring raceway surfaces 241, 241 move away from each other (both sides in the left-right direction of Figure 5; the right side in Figure 6).

[0041] The bearing device 200 comprises an outer ring (outer ring member) 230 having a pair of outer ring raceway surfaces 231, 231 on its inner circumferential surface, an inner ring member 240 having a pair of inner ring raceway surfaces 241, 241 on its outer circumferential surface, a plurality of tapered rollers (rolling elements) 250 rotatably mounted in the respective raceways between the pair of outer ring raceway surfaces 231, 231 and the pair of inner ring raceway surfaces 241, 241, and a pair of cages 260, 260 that hold the plurality of tapered rollers 50 in each row at approximately equal intervals in the circumferential direction. As will be described in detail later, the bearing device 200 includes a sensor 10 that detects the state of lubricant G in the bearing space S between the outer ring 230 and the inner ring member 240. The lubricant G (see Figure 2) is filled in the bearing space S, although it is not shown in Figures 5 and 6.

[0042] The pair of outer ring raceway surfaces 231, 231 are partially conical concave surfaces inclined in a direction where their diameter increases as they move away from each other in the axial direction. The pair of inner ring raceway surfaces 241, 241 are partially conical convex surfaces inclined in a direction where their diameter increases as they move away from each other in the axial direction.

[0043] The inner ring member 240 is constructed by butting a pair of inner rings 242, 242, each having an inner ring raceway surface 241, in the axial direction. The inner ring 242 has a large flange portion 243 provided at the large diameter end relative to the inner ring raceway surface 241, and a small flange portion 244 provided at the small diameter end relative to the inner ring raceway surface 241.

[0044] The tapered roller 250 has a large-diameter end face 251, which is the end face on the large-diameter side; a small-diameter end face 252, which is the end face on the small-diameter side; and a rolling surface 253, which is the circumferential surface.

[0045] The retainer 260 has a large-diameter annular portion 261, a small-diameter annular portion 262, a plurality of columnar portions 263 that connect the large-diameter annular portion 261 and the small-diameter annular portion 262 in the axial direction and are provided at approximately equal intervals in the circumferential direction, and pockets 264 that are formed between adjacent columnar portions 263 in the circumferential direction, surrounded by the large-diameter annular portion 261 and the small-diameter annular portion 262, and that hold the tapered roller 250 so that it can roll.

[0046] Furthermore, the bearing device 200 includes a pair of combination seals (sealing members) 270, 270. The combination seals 270, 270 are provided on both sides in the axial direction between the inner circumferential surface of the protruding portion 232 of the outer ring 230 and the outer circumferential surface 243a of the large flange portion 243 of the inner ring 242, thereby sealing the bearing space S between the outer ring 230 and the inner ring member 240.

[0047] The combination seal 270 comprises a seal ring 271 and a slinger 272 made of a magnetic stainless steel plate or the like, with a roughly L-shaped cross-section. An encoder 273 made of magnetic rubber is fixed to the slinger 272 by vulcanization molding, and the magnetic rubber is magnetized with alternating north and south poles in the circumferential direction at equal pitches.

[0048] The seal ring 271 is composed of a core metal 274 and an elastic material 275. The core metal 274 is formed from a metal plate such as mild steel sheet and has a roughly L-shaped cross-section. The elastic material 275 is formed from an elastic material such as rubber and is bonded to the core metal 274 by vulcanization adhesive molding.

[0049] Through holes 233 are formed in the protruding portions 232 at both axial ends of the outer ring 230, extending radially from the inner circumferential surface to the outer circumferential surface. The through holes 233 are located in the axial direction between the outer ring raceway surface 231 (the tapered roller 250 arranged on the outer ring raceway surface 231) and the combination seal 270. The through holes 233 are cylindrical in shape and extend radially. As described later, the radially inner portion 23 of the sensor 10 is inserted into and fixed in the through holes 233.

[0050] Sensor 10 includes the same configuration as the first embodiment described above. That is, sensor 10 has a main body 20 made of a translucent resin having a detection surface 21 that comes into contact with the lubricant G, and a sensor unit 30 that detects the state of the lubricant G adhering to the detection surface 21. Sensor 10 is inserted from the radially outside into the through hole 233 of the outer ring 230 such that the detection surface 21 faces the radially inner bearing space S, and detects the state of the lubricant G in the bearing space S.

[0051] The sensor 10 is provided at least one location in the circumferential direction of the outer ring 230. The sensor 10 may be provided at multiple locations in the circumferential direction of the outer ring 230. However, considering that the lubricant G is agitated and flows by the tapered rollers 250, providing the sensor at only one location in the circumferential direction of the outer ring 230 is sufficient to obtain the function of detecting the state of the lubricant G.

[0052] The main body portion 20 has a radially inner portion 23 and a radially outer portion 25 that are connected to each other in the radial direction.

[0053] The radially inner portion 23 of the main body 20 is cylindrical in shape and extends radially, and has a detection surface 21 at its radially inner end. In this embodiment, the radially inner portion 23 is substantially the same shape as the through hole 233 of the outer ring 230. When the radially inner portion 23 is inserted into the through hole 233, the outer circumferential surface and both radial end faces of the radially inner portion 23 are positioned to substantially coincide with the inner circumferential surface and the openings at both radial ends of the through hole 233. In other words, the radially inner portion 23 is inserted into the through hole 233 without any gaps.

[0054] The radially outer portion 25 of the main body 20 is connected to the radially outer end of the radially inner portion 23 and is integrally formed with the radially inner portion 23. The radially outer portion 25 is, for example, a cylindrical shape with a larger diameter than the radially inner portion 23. Therefore, the radially outer portion 25 protrudes more from the radially inner portion 23 on both axial sides (see Figure 6) and also protrudes in the circumferential direction.

[0055] In Figure 6, the radially outer portion 25 has the light-emitting element 31 and light-receiving element 33 of the sensor portion 30 embedded in it, and is positioned on the outer circumferential surface of the outer ring 230. Therefore, the light-emitting element 31 and light-receiving element 33 embedded in the radially outer portion 25 are positioned radially outward of the outer ring 230.

[0056] The light-emitting element 31 and the light-receiving element 33 are embedded in the radially outer portion 25 of the main body 20 so as to be spaced apart from each other in the circumferential direction. The arrangement of the light-emitting element 31 and the light-receiving element 33, which is spaced apart from each other in the circumferential direction, is not shown in Figure 6, but it is the same arrangement as in Figure 2 and is therefore not illustrated.

[0057] The sensor 10 has a detection surface 21 on the radially inner surface (the surface on the bearing space S side) of the radially inner portion 23. The sensor 10 detects the state of the lubricant G adhering to the detection surface 21 using the sensor unit 30. As described above, the radially inner portion 23 of this embodiment has substantially the same shape as the through hole 233 of the outer ring 230, so the detection surface 21 of the radially inner portion 23 is positioned substantially at the same location as the radially inner opening 108a of the through hole 233 of the outer ring 230, and therefore its radial position substantially coincides with (is flush with) the inner circumferential surface of the through hole 233 of the outer ring 230.

[0058] Similar to the first embodiment shown in Figure 2, the light-emitting element 31 and the light-receiving element 33 of the second embodiment are also positioned such that, when viewed from the axial direction of the sensor 10, their respective optical axes 31a and 33a are inclined to gradually approach the detection surface 21. As a result, with respect to the axial direction of the sensor 10, the optical axis 31a of the light-emitting element 31 is inclined at an inclination angle α, and the optical axis 33a of the light-receiving element 33 is inclined at an inclination angle β. These optical axes 31a and 33a of the light-emitting element 31 and the light-receiving element 33 intersect at the detection surface 21. Furthermore, since the sensor 10 in the second embodiment is attached to the thin-walled portion adjacent to both ends of the outer ring 230, the inclination angle α of the optical axis 31a of the light-emitting element 31 and the inclination angle β of the optical axis 33a of the light-receiving element 33 can be made larger compared to the first embodiment. Specifically, the inclination angles α and β are set to be in the range of 0° to 45°. Preferably, the inclination angle α of the optical axis 31a of the light-emitting element 31 and the inclination angle β of the optical axis 33a of the light-receiving element 33 are between 15° and 30° and are the same angle (α=β).

[0059] In the sensor unit 30, the light emitter 31 illuminates the lubricant G adhering to the detection surface 21 with light. When the light reflected at the interface between the detection surface 21 and the lubricant G is received by the light receiver 33, the light receiver 33 converts the received light into an electrical signal and outputs it as a detection signal.

[0060] Here, the lubricant G changes color from its initial state (color of the coloring agent) due to oxidation of the base oil, consumption of additives, and deterioration caused by the incorporation of wear materials generated by contact between the outer ring raceway surface 231 and the inner ring raceway surface 241 and the tapered roller 250. For example, lubricant G, which is brown in its initial state, changes to black as it deteriorates, thus reducing its brightness. As a result, the amount of light that reaches the photodetector 33 after being reflected at the interface between the light emitter 31 and the lubricant G decreases. The illuminance of the reflected light reaching the photodetector 33 is proportional to, for example, the voltage of the detection signal from the photodetector 33. Therefore, when the illuminance of the reflected light reaching the photodetector 33 decreases, the voltage of the detection signal output from the photodetector 33 decreases.

[0061] The detection device then determines that the lubricant G has deteriorated based on the detection signal from the photodetector 33 when the amount of light at the photodetector 33 decreases and the voltage of the detection signal falls below a preset threshold. For example, the detection device determines that the deterioration state of the lubricant G is a state requiring attention, a state requiring replacement, or a state where the lifespan has been reached.

[0062] Thus, according to the bearing device 200 of the second embodiment, the amount of reflected light irradiated from the light-emitting body 31 and reflected at the interface between the detection surface 21 and the lubricant G is detected based on the detection signal from the light-receiving body 33. Therefore, it is less susceptible to external disturbances and can accurately grasp the state of the lubricant G adhering to the detection surface 21. Furthermore, the light-emitting element 31 and the light-receiving element 33 are embedded in the main body 20 such that their optical axes 31a and 33a intersect on the detection surface 21, and are positioned radially outward of the outer ring 230. Therefore, compared to the case where the light-emitting element and the light-receiving element are provided on the inner circumferential surface of the outer member, as in Patent Document 1, mounting accuracy can be improved, and wiring work and replacement in case of failure can be made easier. Furthermore, since the light-emitting element 31 and the light-receiving element 33 are positioned radially outward of the outer ring 230, even large, general-purpose components can be positioned without problems, eliminating the need for custom-made components and thus reducing the cost of the sensor 10.

[0063] Furthermore, the outer ring 230 has a through hole 233 that penetrates radially from the inner circumferential surface to the outer circumferential surface of the outer ring 230, and the main body 20 of the sensor 10 has a radially inner portion 23 and a radially outer portion 25 that are connected to each other, the radially inner portion 23 has a detection surface 21 and is inserted into the through hole 233, and the radially outer portion 25 has a light-emitting body 31 and a light-receiving body 33 embedded in it and is arranged on the outer circumferential surface of the outer ring 230. Therefore, by inserting the radially inner portion 23 into the through hole 233, the sensor 10 can be easily and accurately fixed to the bearing device 100.

[0064] In particular, in this embodiment, since the sensor 10 is provided on the protruding portions 232 at both axial ends of the outer ring 230, the radial width of the through hole 233 becomes shorter than the radial width of the through hole 108 in the first embodiment. Therefore, the construction of the through hole 233 becomes easier, and processing costs can be reduced. The sensor 10 may be provided on both of the pair of protruding portions 232, 232 on both axial sides of the outer ring 230, or on just one of them.

[0065] The rolling elements of the bearing device 200 are not limited to tapered rollers 250; for example, balls may also be used. However, in the case of a tapered roller bearing type hub unit bearing in which the bearing device 200 uses tapered rollers 250, as in this embodiment, the radial width of the protruding portion 232 of the outer ring 230 in which the through hole 233 is formed is shorter than the radial width of the protruding portion 102a of the outer ring 102 in which the through hole 108 is formed in the first embodiment.

[0066] Figure 7 shows the bearing device 200 according to the second embodiment attached to the knuckle 280. As shown in Figure 7, the bearing device 200 is attached to the knuckle 280, which has a blind hole in the bearing mounting hole 281 that does not penetrate axially. Since the knuckle 280 is a blind hole, a seal 270 (see Figure 6) does not need to be provided on one axial side (right side in the figure).

[0067] The knuckle 280 is provided with a through-hole 283 that penetrates radially. The through-hole 283 is positioned to be continuous with the through-hole 233 of the outer ring 230. More specifically, the central axes of the two through-holes 233 and 283 are aligned.

[0068] As described above, when the knuckle 280 is provided with a through hole 283, the sensor 10 on one axial side (right side in the figure) can be attached to the knuckle 280. The sensor 10 on the other axial side (left side in the figure) is attached to the outer ring 230, as in the example shown in Figure 5.

[0069] The radially inner portion 23 of the sensor 10 is cylindrical in shape and extends radially, and has a detection surface 21 at its radially inner end. In this embodiment, the radially inner portion 23 is substantially the same shape as the through hole 283 of the knuckle 280. When the radially inner portion 23 is inserted into the through hole 283, the outer circumferential surface and both radial end faces of the radially inner portion 23 are positioned to substantially coincide with the inner circumferential surface and the openings at both radial ends of the through hole 283 of the knuckle 280. In other words, the radially inner portion 23 is inserted into the through hole 283 without any gaps.

[0070] The radially outer portion 25 of the sensor 10 is positioned on a flat sensor seating surface 285 formed on the outer circumferential surface of the knuckle 280. The outer ring 230 is hardened and then ground, but the presence of a flat sensor seating surface to accommodate the radially outer portion 25 of the sensor 10 is detrimental to the shedding of abrasive grains from the grinding wheel during grinding (resulting in deterioration of roughness and adverse effects on the linearity of the contour). Since the knuckle 280 is a part that is neither hardened nor ground, the sensor seating surface 285 can be machined relatively easily.

[0071] As shown by the dashed line in Figure 7, the sensor 10 may be positioned so that its optical axis extends in the axial direction. In this case, the through-hole 283 of the knuckle 280 is provided so as to penetrate the knuckle 280 in the axial direction. The sensor 10 is then positioned in this through-hole 283. In the illustrated example, the sensor 10 faces the large-diameter end face 251 of the tapered roller 250 in the axial direction. The axial inner portion 24 of the sensor 10 fixed in the through-hole 283 is cylindrical in shape and extends in the axial direction, and has a detection surface 21 at its axial inner end. The axial inner portion 24 is substantially the same shape as the through-hole 283 of the knuckle 280. When the axial inner portion 24 is inserted into the through-hole 283, the outer circumferential surface and both axial end faces of the axial inner portion 24 are positioned to substantially coincide with the inner circumferential surface and the openings at both axial ends of the through-hole 283 of the knuckle 280. In other words, the axial inner portion 24 is inserted into the through hole 283 without any gaps. The axial outer portion 26 of the sensor 10 is positioned on the axial outer surface of the knuckle 280.

[0072] Figure 8 is a diagram illustrating a modified example of the through-hole 233 of the outer ring 230. As shown in Figure 8, the through-hole 233 has a small-diameter inner portion 233a that is located radially inward and has dimensions approximately equal to the radially inward portion 23 of the sensor 10, and a large-diameter outer portion 233b that is located radially outward and has dimensions slightly larger than the radially outward portion 25 of the sensor 10.

[0073] The radially inner portion 23 of the sensor 10 is inserted into the inner portion 233a of the through hole 233, and the radially outer portion 25 of the sensor 10 is placed on the outer portion 233b of the through hole 233. At this time, the radially outer portion 25 of the sensor 10 is located inside the outer diameter of the outer ring 230. Therefore, it is possible to avoid interference between the sensor 10 and the knuckle housing.

[0074] (Variation 2-1) Figure 9 is an enlarged cross-sectional view of the bearing device 200 according to Modification 2-1, showing the portion corresponding to Figure 6. Figure 10 is a cross-sectional view along line XX in Figure 9. In this modification, the sensor 10 omits the radially inner portion 23, as shown in Figures 9 and 10. In this case, the detection surface 21 of the sensor 10 is provided on the radially inner end face of the radially outer portion 25. The radially inner end face of the radially outer portion 25, which is also the detection surface 21, can be attached to the sensor seat surface 235, which is provided by planar machining of the outer circumferential surface of the outer ring 230.

[0075] This structure allows for a larger intersection angle between the optical axes 31a and 33a of the light-emitting element 31 and the light-receiving element 33, thereby preventing interference between the light-emitting element 31 and the light-receiving element 33 while suppressing the diameter of the through-hole 233.

[0076] In this case, the inclination angle α of the optical axis 31a of the light-emitting element 31 and the inclination angle β of the optical axis 33a of the light-receiving element 33 are both in the range of 0° to 70°. Preferably, the inclination angle α of the optical axis 31a of the light-emitting element 31 and the inclination angle β of the optical axis 33a of the light-receiving element 33 are between 20° and 40° and are the same angle (α=β).

[0077] (Variation 2-2) Next, a modified example 2-2 of the second embodiment will be described. Note that components identical to those in the second embodiment are denoted by the same reference numerals and their descriptions are omitted. Figure 11 is a cross-sectional view of the bearing device 200 according to modified example 2-2 of the second embodiment.

[0078] In the second embodiment described above, the radial position of the detection surface 21 provided on the radially inner portion 23 of the main body portion 20 of the sensor 10 substantially coincided with the radial position of the inner circumferential surface of the protruding portion 232 of the outer ring 230 (see Figure 6). However, as shown in Figure 11, the radially inner portion 23 of the main body portion 20 of the sensor 10 may extend radially inward beyond the protruding portion 232 of the outer ring 230. In this case, the detection surface 21 may be provided at the radially inner end of the radially inner portion 23 facing radially inward, as in the second embodiment (Figure 6), but it may also be provided at the radially inner end of the radially inner portion 23 facing axially inward, as shown in Figure 11.

[0079] In this modified example, the detection surface 21 is positioned to face axially opposite the outer ring raceway surface 231 and the large-diameter end face 251 of the tapered roller 250. This allows the sensor 10 to determine the degree of deterioration of the lubricant G extruded from the outer ring raceway surface 231.

[0080] Furthermore, in order to insert the radially inner portion 23 into the through hole 233, the radially outer portion of the radially inner portion 23 that is inserted into the through hole 233 needs to be cylindrical. However, the detection surface 21 formed on the portion of the radially inner portion 23 that protrudes radially inward from the through hole 233 is provided by cutting out a flat section of the cylindrical shape of the radially inner portion 23 (the left side of Figure 11) so that it faces axially inward. By making the detection surface 21 a flat surface rather than a cylindrical surface in this way, scattering of reflected light reaching the photodetector 33 can be further prevented.

[0081] In this modified example, a mirror 40 that changes the optical axes 31a and 33a of the light emitter 31 and the light receiver 33 is embedded in the radially inner end of the radially inner portion 23. The mirror 40 is positioned at a 45° angle with respect to the axial direction. Therefore, the emitted light from the light emitter 31, irradiated radially inward, is changed in direction by the mirror 40 to axially inward before reaching the detection surface 21. Then, the reflected light, reflected axially outward at the interface between the detection surface 21 and the lubricant G, is changed in direction by the mirror 40 to radially outward before reaching the light receiver 33. Thus, in this modified example as well, the optical axes 31a and 33a of the light emitter 31 and the light receiver 33 intersect at the detection surface 21.

[0082] Furthermore, since the sensor 10 is integrally provided with the light-emitting element 31, the light-receiving element 33, the mirror 40, and the detection surface 21, refraction (a change in refractive index with the wavelength of light) is prevented, and scattering of reflected light reaching the light-receiving element 33 is prevented.

[0083] The detection surface 21 may be tapered so as to be parallel to the tangent to the large-diameter end face 251 of the tapered roller 250. In this way, the distance between the large-diameter end face 251 of the tapered roller 250 and the detection surface 21 can be reduced, making it easier for the lubricant G to adhere to the detection surface 21 and promoting the replacement of the lubricant G adhering to the detection surface 21. Moreover, the large-diameter end face 251 of the tapered roller 250 is lubricated by the lubricant G adhering to the detection surface 21, and the return of the lubricant G to the large flange surface 243b of the large flange portion 243 is promoted, thereby reducing the torque in the bearing device 200 and suppressing seizure.

[0084] (Variations 2-3) Next, a modified example 2-2 of the second embodiment will be described. Note that components identical to those in the second embodiment are denoted by the same reference numerals and their descriptions are omitted. Figure 12 is a cross-sectional view of the bearing device 200 according to modified example 2-3 of the second embodiment.

[0085] In this modified example, since the outer ring 230 does not have a through hole 233 for fixing the sensor 10, the cost of machining the through hole 233 is eliminated.

[0086] The sensor 10 is positioned on the protruding portion 232 at the axial end of the outer ring 230 and has a substantially L-shaped cross-section overall. The main body 20 of the sensor 10 has a radially inner portion 23 and a radially outer portion 25 that are connected to each other. The radially inner portion 23 is fitted and fixed to the inner circumferential surface of the protruding portion 232 of the outer ring 230 and has a substantially linear cross-section that extends axially beyond the outer ring 230. The radially outer portion 25 has a substantially linear cross-section that extends radially outward from the axially outer end of the radially inner portion 23 and abuts the protruding portion 232 of the outer ring 230 in the axial direction. The radially outer portion 25 protrudes radially outward from the protruding portion 232 of the outer ring 230, and the light-emitting body 31 and the light-receiving body 33 are embedded in this protruding portion.

[0087] In this modified example, the detection surface 21 is provided on the radially inner portion 23 that extends in the axial direction, and faces the outer ring raceway surface 231 and the large-diameter end face 251 of the tapered roller 250 in the axial direction. This allows the sensor 10 to determine the degree of deterioration of the lubricant G extruded from the outer ring raceway surface 231.

[0088] In this modified example, a mirror 40 that changes the optical axes 31a and 33a of the light emitter 31 and the light receiver 33 is embedded in the axial outer end of the radially inner portion 23. The mirror 40 is positioned at a 45° angle with respect to the axial direction. Therefore, the emitted light from the light emitter 31, irradiated radially inward, is redirected axially inward by the mirror 40 and reaches the detection surface 21. The reflected light, reflected axially outward at the interface between the detection surface 21 and the lubricant G, is redirected radially outward by the mirror 40 and reaches the light receiver 33. Thus, in this modified example as well, the optical axes 31a and 33a of the light emitter 31 and the light receiver 33 intersect at the detection surface 21. The detection surface 21 may be tapered so as to be parallel to the tangent to the large-diameter end face 251 of the tapered roller 250.

[0089] The combination seal 270 that seals the bearing space S is provided between the inner circumferential surface of the radially inner portion 23 of the sensor 10 and the outer circumferential surface 243a of the large flange portion 243 of the inner ring 242. In this case, since the inner circumferential surface of the sensor 10 becomes the fitting surface of the combination seal 270, if the combination seal 270 is pressed in after the sensor 10 is pressed into the protruding portion 232 of the outer ring 230, there is a risk that the sensor 10 will move in the axial direction due to the combination seal 270 being pressed in. Therefore, it is preferable to assemble the combination seal 270 by pressing the core metal 274 into the sensor 10 in advance, and then simultaneously fit the sensor 10 and the combination seal 270 into the space between the large flange portion 243 of the inner ring 242 and the protruding portion 232 of the outer ring 230. This allows the sensor 10 and the combination seal 270 to be fixed in the appropriate position between the large flange portion 243 of the inner ring 242 and the protruding portion 232 of the outer ring 230.

[0090] As shown in Figure 12, a locking portion 23a for engaging the core metal 274 of the combination seal 270 may be formed on the inner circumference of the radially inner portion 23 of the sensor 10 so as to protrude radially inward. This improves the press-fitting performance when fitting the assembled sensor 10 and combination seal 270 into the space between the large flange portion 243 of the inner ring 242 and the protruding portion 232 of the outer ring 230. The core metal 274 of the combination seal 270 may be molded and fixed to the radially inner portion 23 of the sensor 10.

[0091] (Modification 2-4) Next, a modified example 2-4 of the second embodiment will be described. Note that components identical to those in the second embodiment are denoted by the same reference numerals and their descriptions are omitted. Figure 13 is a cross-sectional view of the bearing device 200 according to modified example 2-4 of the second embodiment.

[0092] In this modified example 2-4, instead of the mirror 40 in the modified example 2-3 described above, a chamfer 50 is formed on the main body 20 of the sensor 10 between the light-emitting element 31 and the light-receiving element 33 and the detection surface 21. The chamfer 50 is a mirror surface that changes the direction of the optical axes 31a and 33a. The chamfer 50 is formed to be inclined at 45° with respect to the axial direction.

[0093] The mirror finish of the chamfer 50 is achieved by methods such as vapor deposition or vacuum plating of a metal material suitable for mirrors, such as silver, tin, or aluminum, or by mirror spray application. The method of mirror finishing is not particularly limited; mirror finishing by cutting or polishing may also be applied. After mirror finishing, protecting the chamfer 50 with enamel or sealant allows for obtaining the function of bending the optical axes 31a and 33a at a lower cost compared to embedding a mirror 40.

[0094] (Variations 2-5) Next, a modified example 2-5 of the second embodiment will be described. Note that components identical to those in the second embodiment are denoted by the same reference numerals and their descriptions are omitted. Figure 14 is a cross-sectional view of the bearing device 200 according to modified example 2-5 of the second embodiment.

[0095] The sensor 10 in this modified example 2-5 differs from the sensor 10 in modified example 2-3 (see Figure 12), which has a roughly L-shaped cross-section, in that its cross-section is roughly U-shaped.

[0096] In this modified example, the sensor 10 is positioned on the protruding portion 232 at the axial end of the outer ring 230 and has a substantially U-shaped cross-section overall. The main body portion 20 of the sensor 10 has a radially inner portion 23 and a radially outer portion 25 that are connected to each other. The radially inner portion 23 is fitted and fixed to the inner circumferential surface of the protruding portion 232 of the outer ring 230 and has a substantially linear cross-section that extends axially beyond the outer ring 230 to the axially outer side.

[0097] The radially outer portion 25 has a substantially L-shaped cross-section, comprising a first portion 25a extending radially outward from the axially outer end of the radially inner portion 23, and a second portion 25b extending axially inward from the radially outer end of the first portion 25a.

[0098] The first portion 25a of the radially outer portion 25 abuts axially with the protruding portion 232 of the outer ring 230. The light-emitting body 31 and the light-receiving body 33 are embedded in the axially inner end of the second portion 25b.

[0099] Furthermore, in this modified example, the outer surface of the outer ring 230 has a smaller outer diameter than the axial end of the overhang 232, and the outer surface of the overhang 232 is a small-diameter stepped portion 232a. The second portion 25b of the radially outer portion 25 is fitted and fixed onto this small-diameter stepped portion 232a. The outer diameter of the outer surface of the second portion 25b is approximately equal to the outer diameter of the outer surface of the outer ring 230, and therefore the outer surface of the second portion 25b and the outer surface of the outer ring 230 are flush.

[0100] Mirrors 40 are embedded in the axial outer end of the radially inner portion 23 and in the connection between the first portion 25a and the second portion 25b of the radially outer portion 25, respectively, to change the optical axes 31a and 33a of the light emitter 31 and the light receiver 33. The mirrors 40 are positioned at a 45° angle with respect to the axial direction. Therefore, the emitted light from the light emitter 31 directed axially outward is sequentially changed in direction radially inward and axially inward by the pair of mirrors 40, 40, and reaches the detection surface 21. The reflected light reflected axially outward at the interface between the detection surface 21 and the lubricant G is then sequentially changed in direction radially outward and axially inward by the pair of mirrors 40, 40, and reaches the light receiver 33. The detection surface 21 may be tapered so as to be parallel to the tangent to the large-diameter end face 251 of the tapered roller 250.

[0101] As described above, in this modified example, a small-diameter stepped portion 232a is provided on the outer circumferential surface of the outer ring 230, and the main body portion 20, in which the light-emitting element 31 and light-receiving element 33 are embedded, can be arranged in this small-diameter stepped portion 232a. This reduces the influence of the sensor 10 on the knuckle dimensions. In other words, the interference area between the sensor 10 and the knuckle is reduced, and the portion of the knuckle that needs to be partially removed can be reduced. Note that partial removal requires milling, which is significantly more expensive than turning. In this way, the cost of the knuckle can be reduced, and the risk of the sensor 10 coming loose or being damaged due to accidental collision between the sensor 10 and the knuckle during assembly of the hub unit bearing is prevented.

[0102] (Variation 2-6) Next, a modified example 2-6 of the second embodiment will be described. Note that components identical to those in the second embodiment are denoted by the same reference numerals and their descriptions are omitted. Figure 15 is a cross-sectional view of the bearing device 200 according to modified example 2-6 of the second embodiment.

[0103] In this modified example 2-6, instead of the pair of mirrors 40, 40 in the modified example 2-5 described above, a pair of chamfers 50, 50 are formed on the main body 20 of the sensor 10 between the light-emitting element 31 and the light-receiving element 33 and the detection surface 21. The chamfers 50 are mirror surfaces that change the direction of the optical axes 31a, 33a. The chamfers 50 are formed to be inclined at 45° with respect to the axial direction.

[0104] The mirror finish of the chamfer 50 is achieved by methods such as vapor deposition or vacuum plating of a metal material suitable for mirrors, such as silver, tin, or aluminum, or by mirror spray application. The method of mirror finishing is not particularly limited; mirror finishing by cutting or polishing may also be applied. After mirror finishing, protecting the chamfer 50 with enamel or sealant allows for obtaining the function of bending the optical axes 31a and 33a at a lower cost compared to embedding a mirror 40.

[0105] (Third embodiment) Figure 16 is a cross-sectional view of the bearing device 100A according to the third embodiment. As shown in Figure 16, the bearing device 100A according to the third embodiment is a third-generation hub unit bearing in which the rolling elements are tapered rollers 250, and the main components are the same as those of the bearing device 100 of the first embodiment (see Figure 1), in which the rolling elements were balls 105. Therefore, the same reference numerals are used in the drawings for parts that are the same as those of the bearing device of the first embodiment, and their descriptions are omitted.

[0106] Through holes 108 are formed in the protruding portions 102a at both axial ends of the outer ring 102, extending radially from the inner circumferential surface to the outer circumferential surface. Each through hole 108 is positioned in the axial direction between the outer ring raceway surface 101 and the seals 107 and 107a. The through holes 108 are cylindrical in shape and extend radially. The radially inner portion 23 of the sensor 10 is inserted into and fixed to the through hole 108 on the outboard side.

[0107] Figure 16 shows the bearing device 100A according to the third embodiment attached to the knuckle 280. A backing plate 112, on which various brake components such as brake shoes are mounted, is supported and fixed between the knuckle 280 and the outer ring 102 in the axial direction.

[0108] The knuckle 280 is provided with a through-hole 283 that penetrates radially. The through-hole 283 is positioned to be continuous with the through-hole 108 on the inboard side of the outer ring 102. The central axes of the two through-holes 283 and 108 are aligned.

[0109] Thus, when the knuckle 280 is provided with a through hole 283, the inboard sensor 10 can be attached to the knuckle 280. The outboard sensor 10 is attached to the outer ring 102.

[0110] The outer ring 102 of the bearing device 100A in this embodiment is further provided with at least one observation through-hole 111. In the illustrated example, a pair of observation through-holes 111, 111 are formed in the protruding portions 102a at both axial ends of the outer ring 102, penetrating radially from the inner circumferential surface to the outer circumferential surface. Each observation through-hole 111 is positioned in the axial direction between the outer ring raceway surfaces 101, 101 and the seals 107, 107a. These pairs of observation through-holes 111, 111 are positioned in a different phase in the circumferential direction from the through-hole 108 described above. Note that, as shown by the dashed line in Figure 16, the observation through-holes 111 may also be provided between the rows (between the pair of outer ring raceway surfaces 101, 101).

[0111] The observation through-hole 111 may have any shape; for example, it may be a round hole when viewed from the radial direction, or it may be an elongated hole that is longer in the axial direction when viewed from the radial direction.

[0112] A lubricant degradation detection window material 120 is inserted and fixed into the observation through-hole 111. This allows for visual confirmation of the lubricant's color within the bearing space S. The lubricant degradation detection window material 120 is formed from a resin that has high heat resistance and light transmission, such as acrylic resin or polycarbonate resin.

[0113] Figure 17 shows a view of the lubricant degradation detection window material 120 fitted into the observation through hole 111, when the observation through hole 111 is a round hole when viewed from the radial direction. The lubricant degradation detection window material 120 in Figure 17 is round when viewed from the radial direction, and consists of multiple signal colors 123, multiple color samples 122, and a transparent section 124 arranged in order from the radial outside to form an indicator.

[0114] Figure 18 shows a view of the lubricant degradation detection window material 120 fitted into the observation through hole 111, when the shape of the observation through hole 111, as viewed from the radial direction, is an elongated hole shape that is longer in the axial direction. The lubricant degradation detection window material 120 in Figure 18 has a shape that corresponds to an elongated hole, which is longer in the axial direction when viewed from the radial direction. The lubricant degradation detection window material 120 is configured as an indicator by repeatedly arranging multiple signal colors 123, multiple color samples 122, and multiple transparent parts 124 in the circumferential direction, starting from one side in the axial direction.

[0115] The radially inner surface of the lubricant degradation detection window material 120 is the surface to which the lubricant adheres, and the hue of the lubricant in the bearing space S can be visually observed through the transparent part 124. Multiple color samples 122 are for comparison with the hue of the lubricant observed through the transparent part 124, and are arranged in the order of the degree of lubricant degradation, for example, white 122a (new condition), light brown 122b (condition due to thermal degradation), black 122c (condition where the bearing has suffered damage such as flaking), and dark brown 122d (condition where water has entered the bearing space S). In addition, signal colors 123 are used to give instructions to the monitor based on the degree of lubricant degradation, for example, green (no problem) 123a, yellow (caution required) 123b, red (replacement required due to end of life) 123c, and purple (replacement required due to water intrusion) 123d.

[0116] Then, the degree of lubricant deterioration is determined by visually observing the color of the lubricant attached to the radially inner surface of the lubricant deterioration detection window material 120 from the radially outer side during periodic inspections, and comparing it with the color sample 122.

[0117] In other words, lubricants change color from their new state (e.g., white) to brown and then to black due to oxidation and degradation of the base oil, consumption of additives, and the incorporation of wear particles generated by contact between the raceway surface, large flange surface, and tapered rollers. By comparing the changing color of the lubricant with color sample 122, the deterioration state of the grease can be determined.

[0118] In this embodiment, the sensor 10 reflects light emitted from the light-emitting element 31 off a lubricant adhering to the detection surface 21, and measures the amount of reflection with a photodetector 33 to determine the degree of lubricant degradation. However, the amount of light reflected is affected not only by the color of the lubricant but also by the thickness of the lubricant adhering to the detection surface 21. That is, if the lubricant adhering to the detection surface 21 is thin, the amount of light transmitted through the lubricant increases, the amount of reflection decreases, and even if the lubricant is the same color, the photodetector may judge that it is more degraded (darker color, less reflected light). However, in this embodiment, which is provided with a lubricant degradation detection window material 120, it becomes possible to observe the appearance of the lubricant, thus compensating for false alarms from the photodetector 33.

[0119] Furthermore, if the bearing device 100 is a second-generation or third-generation hub unit with inner ring rotation, the mounting phase between the outer ring 102 of the bearing device 100 and the knuckle 280 is uniquely determined, making it possible to insert a sensor and observe the lubricant via the knuckle 280. Figure 16 shows an example in which the knuckle 280 is provided with an observation through-hole 287 that penetrates radially at a position that overlaps with the observation through-hole 111 in the circumferential and axial directions. Through this observation through-hole 287, it is possible to observe the lubricant using a lubricant deterioration detection window material 120 fixed to the observation through-hole 111 of the outer ring 102.

[0120] Thus, the present invention is not limited to the embodiments described above. It is also intended and within the scope of protection to be provided for the combination of each configuration of the embodiments, as well as for modifications and applications by those skilled in the art based on the description in the specification and well-known technology.

[0121] As described above, the following matters are disclosed in this specification: (1) An outer ring member having an outer ring raceway surface on its inner circumferential surface, An inner ring member having an inner ring raceway surface on its outer circumferential surface, A plurality of rolling elements are provided to be rotatable in the raceway between the outer ring raceway surface and the inner ring raceway surface, A lubricant disposed in the bearing space between the inner circumferential surface of the outer ring member and the outer circumferential surface of the inner ring member, A sensor for detecting the state of the lubricant, A bearing device comprising, The aforementioned sensor is A main body made of a translucent resin having a detection surface in contact with the lubricant, A light-emitting element embedded in the main body and irradiating light toward the detection surface, A light-receiving element embedded in the main body receives light reflected at the interface between the detection surface and the lubricant and outputs a detection signal, It has, The light-emitting element and the light-receiving element are embedded in the main body so that their optical axes intersect at the detection surface, and are positioned radially outward of the outer ring member. Bearing device. (2) The outer ring member has a through hole that penetrates radially from the inner circumferential surface to the outer circumferential surface of the outer ring member, The main body of the sensor has a radially inner portion and a radially outer portion that are connected to each other. The radially inner portion has the detection surface and is inserted into the through hole. The radially outer portion is in which the light-emitting element and the light-receiving element are embedded and arranged on the outer circumferential surface of the outer ring member. (1) The bearing device described above. (3) The sensor is positioned at the axial end of the outer ring member, The main body of the sensor has a radially inner portion and a radially outer portion that are connected to each other. The radially inner portion is fitted into the inner circumferential surface of the axial end of the outer ring member and extends axially outward from the outer ring member. The radially outer portion extends radially outward from the axially outer end of the radially inner portion, and the light-emitting body and the light-receiving body are embedded within it. (1) The bearing device described above. (4) A sealing member is provided between the inner circumferential surface of the sensor and the inner ring member to seal the bearing space. (3) The bearing device described above. (5) The main body of the sensor has a mirror embedded between the light-emitting element, the light-receiving element, and the detection surface that changes the direction of the optical axis. A bearing device as described in any one of (1) to (4). (6) The main body of the sensor has a chamfer formed between the light-emitting element, the light-receiving element, and the detection surface. The aforementioned chamfer is a mirror surface that changes the direction of the optical axis. A bearing device as described in any one of (1) to (4). (7) A method for detecting the lubricant state in a bearing device as described in any one of (1) to (6), The light source of the sensor is used to emit light, Based on the detection signal from the light receiver of the sensor, the amount of reflected light from the light emitter reflected at the interface between the detection surface and the lubricant is detected. Based on the amount of light, the deterioration state of the lubricant is determined. A method for detecting the state of lubricant. [Explanation of symbols]

[0122] 10 sensors 20 Main body 21 Detection surface 23 Radial inner portion 23a Locking part 24 Inner axial part 25 Radial outer portion 25a First part 25b Second part 26 Axial outer part 30 Sensor section 31. Luminous body 31a Optical axis 33 Photodetector 33a optical axis 40 mirror 50 Chamfer 100 Bearing device 101 Outer ring raceway 102 Outer ring (outer ring member) 102a Overhang (axial end) 102b Flange section 102c hole 103 Inner ring track surface 104 Inner ring member 104a Inner ring 104b Flange section 104c hole 104d Small diameter stepped section 104e hub wheel 105 Ball (rolling element) 106 Cage 107 Seal (sealing material) 107a Combination seal (sealing component) 108 Through hole 108a aperture 109 Seat 110 volts 111 Observation through-hole 112 Backing Plate 120 Lubricant Degradation Detection Window Material 122 Color Swatches 123 Signal Colors 124 Transparent part 200 Bearing device 230 Outer ring (outer ring component) 231 Outer ring raceway surface 232 Overhang (axial end) 232a Small diameter stepped section 233 Through hole 235 Sensor seat 240 Inner ring member 241 Inner ring raceway surface 242 Inner Ring 243 Otsubabe 243a Outer surface 243b Large Tsuba Face 244 Small guard section 250 yen (rolling element) 251 Large diameter side end face 252 Small diameter side end face 253 Rolling surface 260 Retainer 261 Large diameter annular section 262 Small diameter side annular part 263 Column 264 pockets 270 Combination seals (sealing components) 271 Seal ring 272 Slinger 273 encoders 274 Mandrel 275 Elastic material 280 Knuckle 281 Bearing mounting hole 283 Through hole 285 Sensor seat 287 Observation through-hole G Lubricant O Rotation axis S bearing space

Claims

1. An outer ring member having an outer ring raceway surface on its inner circumferential surface, An inner ring member having an inner ring raceway surface on its outer circumferential surface, A plurality of rolling elements are provided to be rotatable in the raceway between the outer ring raceway surface and the inner ring raceway surface, A lubricant disposed in the bearing space between the inner circumferential surface of the outer ring member and the outer circumferential surface of the inner ring member, A sensor for detecting the state of the lubricant, A bearing device comprising, The aforementioned sensor is A main body made of a translucent resin having a detection surface in contact with the lubricant, A light-emitting element embedded in the main body and irradiating light toward the detection surface, A light-receiving element embedded in the main body receives light reflected at the interface between the detection surface and the lubricant and outputs a detection signal, It has, The light-emitting element and the light-receiving element are embedded in the main body so that their optical axes intersect at the detection surface, and are positioned radially outward of the outer ring member. Bearing device.

2. The outer ring member has a through hole that penetrates radially from the inner circumferential surface to the outer circumferential surface of the outer ring member, The main body of the sensor has a radially inner portion and a radially outer portion that are connected to each other. The radially inner portion has the detection surface and is inserted into the through hole. The radially outer portion is in which the light-emitting element and the light-receiving element are embedded and arranged on the outer circumferential surface of the outer ring member. The bearing device according to claim 1.

3. The sensor is positioned at the axial end of the outer ring member. The main body of the sensor has a radially inner portion and a radially outer portion that are connected to each other. The radially inner portion is fitted into the inner circumferential surface of the axial end of the outer ring member and extends axially outward from the outer ring member. The radially outer portion extends radially outward from the axially outer end of the radially inner portion, and the light-emitting body and the light-receiving body are embedded within it. The bearing device according to claim 1.

4. A sealing member is provided between the inner circumferential surface of the sensor and the inner ring member to seal the bearing space. The bearing device according to claim 3.

5. The main body of the sensor has a mirror embedded between the light-emitting element, the light-receiving element, and the detection surface that changes the direction of the optical axis. The bearing device according to claim 1.

6. The main body of the sensor has a chamfer formed between the light-emitting element, the light-receiving element, and the detection surface. The aforementioned chamfer is a mirror surface that changes the direction of the optical axis. The bearing device according to claim 1.

7. A method for detecting the lubricant state in a bearing device according to any one of claims 1 to 6, The light source of the sensor is used to emit light, Based on the detection signal from the light receiver of the sensor, the amount of reflected light from the light emitter reflected at the interface between the detection surface and the lubricant is detected. Based on the amount of light, the deterioration state of the lubricant is determined. A method for detecting the state of lubricant.

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