Bearing device

Abstract

Provided is an economical bearing device in which the state of a rolling bearing can be detected by a wireless sensor unit. A bracket (3) is fixed to a first bearing race (6) of a rolling bearing (1). The bracket (3) is joined to one of two side surfaces (6c) that define the width of the first bearing race (6). The wireless sensor unit (2) has: a substrate (12) with a sensor and a wireless communication circuit (14); and a power source (15). The wireless sensor unit (2) is detachably fastened to the bracket (3) through a screw member (4).

Description

Bearing device

[0001] The present invention relates to a bearing device including a rolling bearing and a wireless sensor unit.

[0002] A conventional bearing assembly is known in which a sensor or the like for detecting the condition of a rolling bearing is mounted on a substrate to form a sensor-equipped circuit board, the circuit board is held in a holder to assemble it into a sensor unit, and the sensor unit is then fixed to a bearing ring. The condition of the rolling bearing is generally determined by detecting temperature and vibration.

[0003] The bearing device disclosed in Patent Document 1 includes a rolling bearing conforming to a specific standard, such as ISO or JIS, with a sensor unit housed between its first and second races. The first race is machined with a step for fitting and positioning the sensor unit. A wireless communication circuit for transmitting data acquired by the sensor is also mounted on the circuit board. The sensor unit is also equipped with a power generation circuit and a battery or other power source for supplying power to the circuit board. The adoption of these wireless transmission and power sources results in a wireless sensor unit, eliminating the need for wired connections between the bearing device and the outside world. Thus, the bearing device disclosed in Patent Document 1 utilizes standard rolling bearings to reduce costs. Furthermore, since the entire wireless sensor unit is housed between the first and second races, it can be provided with the same inner and outer diameters and widths as a standard rolling bearing.

[0004] Japanese Patent Application Laid-Open No. 2023-141395

[0005] The bearing device disclosed in Patent Document 1 can achieve the same compactness as a standard rolling bearing, but it requires a special raceway with a stepped portion for the wireless sensor unit, which is a disadvantage when low cost is more important than compactness of the bearing device.

[0006] Furthermore, in the bearing device disclosed in Patent Document 1, the wireless sensor unit is fixed to the step of the first bearing ring by press-fitting, adhesive, or the like, making it difficult to remove the wireless unit from the first bearing ring when the rolling bearing needs to be replaced, and therefore difficult to reuse the removed wireless sensor unit.

[0007] In view of the above background, an object of the present invention is to provide an economical bearing device that is capable of detecting the state of a rolling bearing with a wireless sensor unit.

[0008] In order to solve the above problems, the present invention employs Configuration 1, which is a bearing device comprising: a rolling bearing having a first raceway, a second raceway, and a plurality of rolling elements arranged between the first raceway and the second raceway; a wireless sensor unit having a substrate, one or more sensors and a wireless communication circuit mounted on the substrate, and a power source for supplying power to the substrate; and a bracket fixed to the first raceway, wherein the wireless sensor unit is configured to be detachable from the bracket, and the bracket is joined to one of two side surfaces that define the width of the first raceway.

[0009] According to the above-mentioned configuration 1, a bracket is joined to one of the two sides that define the width of the first bearing ring, and a wireless sensor unit is attached to the bracket. This allows the condition of the rolling bearing to be detected by the wireless sensor unit, but eliminates the need for a special first bearing ring with a stepped portion for the wireless sensor unit, thereby reducing the procurement costs of the rolling bearing. Furthermore, because the wireless sensor unit is configured to be detachable from the bracket, when replacing the rolling bearing, the wireless sensor unit that was attached to the first bearing ring before the replacement can be reused, thereby reducing running costs. In this way, the reduction in procurement costs and running costs makes the bearing device economical.

[0010] In the above configuration 1, a configuration 2 can be adopted in which the bracket is welded or bonded to the side surface of the first bearing ring.

[0011] According to the above-mentioned configuration 2, the side surface of the first bearing ring and the bracket are welded or bonded together, so that the bracket can be fixed to the side surface of the first bearing ring.

[0012] In the above configuration 2, a configuration 3 can be adopted in which the bracket has a side plate portion that faces the annular space formed between the first raceway ring and the second raceway ring in the axial direction, and the wireless sensor unit is fastened to the side plate portion.

[0013] According to the above configuration 3, the radial length of the side surface of the bracket is extended by utilizing the radial range that faces axially the annular space of the rolling bearing, so that a wireless sensor unit that is radially longer than the side surface of the first bearing ring can be fastened to the bracket.

[0014] In the above configuration 3, a configuration 4 can be adopted in which the bracket has a tubular portion welded or glued so as to be in abutment against the side surface of the first raceway, and the side plate portion is continuous with the tubular portion and extends from the radially outer side to the radially inner side.

[0015] According to the above-mentioned configuration 4, the cylindrical portion and the side plate portion of the bracket form an annular body with an L-shaped cross section, which makes the bracket more rigid than a bracket with a linear cross section. This makes the bracket less susceptible to vibration, which makes it easier to stabilize detection by the sensor of the wireless sensor unit fastened to the bracket.

[0016] In the above configuration 4, a configuration 5 can be adopted in which the rolling bearing is a sealed bearing, and the seal is disposed between the side plate portion of the bracket and the plurality of rolling elements.

[0017] According to the fifth aspect, interference between the bracket and the seal can be prevented by providing a distance between the side plate and the seal equal to the axial length of the cylindrical portion of the bracket joined to the side surface of the first raceway ring. Therefore, even if a general sealed bearing is used as a rolling bearing, the same sealing performance can be ensured.

[0018] In any one of the above configurations 1 to 5, a configuration 6 can be adopted in which the side surface of the first bearing ring has an annular radial region that is exposed when viewed in the axial direction.

[0019] According to the above-mentioned configuration 6, the side surface of the first raceway has an annular radial region that is not covered by the wireless sensor unit and the bracket and is exposed in the axial direction, so that the radial region can be abutted against another mechanical component in the axial direction to determine the axial position of the rolling bearing.

[0020] In any one of the above configurations 1 to 6, a configuration 7 can be adopted, further comprising a magnetic ring fixed to the second raceway and having alternating north and south poles in the circumferential direction, the power supply having a stator that converts the alternating magnetic field of the magnetic ring caused by the relative rotation of the first raceway and the second raceway into alternating current power, the second raceway having two side surfaces that define the width of the second raceway, and the magnetic ring being joined to one of the side surfaces of the second raceway.

[0021] According to the seventh aspect, AC power can be supplied to the substrate using the stator as a power source while the rolling bearing is in operation. In addition, because the magnetic ring is joined to one of the two side surfaces that define the width of the second bearing ring, it is not necessary to use a special second bearing ring with a stepped portion for the magnetic ring.

[0022] In the above configuration 7, a configuration 8 can be adopted in which the magnetic ring is welded or bonded to the side surface of the second bearing ring.

[0023] According to the above configuration 8, the magnetic ring can be fixed to the side surface of the second bearing ring.

[0024] In the above-described configuration 7 or 8, a configuration 9 can be adopted in which the side surface of the second bearing ring has an annular radial region that is exposed when viewed from the axial direction.

[0025] According to the above-mentioned configuration 9, the side surface of the second raceway has an annular radial region that is not covered by the magnetic ring and is exposed in the axial direction, so that the annular radial region can be abutted against another mechanical component in the axial direction to determine the axial position of the rolling bearing.

[0026] In any one of the above configurations 1 to 9, configuration 10 can be adopted, in which the wireless sensor unit has a holding member axially stacked on the bracket and a protective member combined with the holding member, the substrate is housed between the holding member and the protective member, and the wireless communication circuit has an antenna exposed from a hole formed in the protective member.

[0027] According to the above configuration 10, the substrate can be protected by the holding member and the protective member, while the antenna is exposed through a hole in the protective member, thereby suppressing a decrease in wireless communication performance due to the dielectric constant of the protective member.

[0028] As described above, by adopting the above configuration 1, the present invention can provide an economical bearing device that is capable of detecting the state of the rolling bearing with a wireless sensor unit.

[0029] 1 is an exploded perspective view showing the holding member and protective member of the wireless sensor unit of FIG. 1 in a separated state; FIG. 9 is an exploded perspective view showing the rolling bearing, bracket, and magnetic ring in a separated state; FIG. 1 is an enlarged view of the antenna and its vicinity in FIG. 1; FIG. 1 is an enlarged view of the screw member and its vicinity in FIG. 1;

[0030] 1 to 7 show a bearing device according to a first embodiment of the present invention (hereinafter referred to as "this bearing device").

[0031] As shown in Figures 1 and 2, this bearing device comprises a rolling bearing 1 that is incorporated between a shaft 100 and a housing 110 of another device, a wireless sensor unit 2 that monitors the state of the rolling bearing 1 and transmits the state of the rolling bearing 1 to the outside, a bracket 3 that is used to connect the rolling bearing 1 and the wireless sensor unit 2, a plurality of screw members 4 that are used to fasten the wireless sensor unit 2 to the bracket 3, and a magnetic ring 5 that generates an alternating magnetic field for the wireless sensor unit 2 while the rolling bearing 1 is in operation.

[0032] Hereinafter, the direction along the circumference of the rolling bearing 1 centered on the bearing central axis will be referred to as the "circumferential direction," the direction along the bearing central axis will be referred to as the "axial direction," and the direction perpendicular to the bearing central axis will be referred to as the "radial direction." Furthermore, within the axial direction, the direction approaching the rolling elements will be referred to as the "axial inner direction," and the direction away from the rolling elements will be referred to as the "axial outer direction." Within the radial direction, the direction approaching the bearing's rotation axis will be referred to as the "radial inner direction," and the direction away from the rotation axis will be referred to as the "radial outer direction."

[0033] The rolling bearing 1 has a first raceway 6, a second raceway 7, a plurality of rolling elements 8 arranged between the first raceway 6 and the second raceway 7, and a cage 9 that maintains the circumferential spacing of these rolling elements 8. These rolling elements 8 and cage 9 are housed in an annular space 10 formed between the first raceway 6 and the second raceway 7.

[0034] The rolling bearing 1 is a radial bearing. The rolling bearing 1 is also a standard bearing that complies with a specific standard. Here, a standard bearing refers to a bearing that satisfies the dimensions specified in an ISO or JIS standard. For example, the dimensions of radial bearings other than tapered roller bearings are specified in ISO 15 or JIS B 1512-1.

[0035] The first bearing ring 6 is an outer ring having an inner circumference including a raceway surface 6a, an outer circumference including a fitting surface 6b, and two side surfaces 6c that define the width (total axial length) of the first bearing ring 6.

[0036] The second bearing ring 7 is an inner ring having an outer periphery including a raceway surface 7a, an inner periphery including a fitting surface 7b, and two side surfaces 7c that define the width (total axial length) of the second bearing ring 7. The width of the second bearing ring 7 is set to be the same as the width of the first bearing ring 6.

[0037] Each of the fitting surfaces 6b, 7b is curved in the circumferential and axial directions and is fitted onto a corresponding shaft 100 or housing 110. Each of the side surfaces 6c, 7c is formed into a circular ring shape that extends radially and completely around the circumference.

[0038] The first bearing ring 6 is normally arranged as a stationary ring, and the second bearing ring 7 is normally arranged as a rotating ring. The rolling elements 8 are balls that roll between the raceway surfaces 6 a and 7 a.

[0039] Although the rolling bearing 1 is exemplified as a deep groove ball bearing, the rolling bearing is not limited to a deep groove ball bearing and may be changed to various bearings such as an angular ball bearing or a self-aligning bearing.

[0040] The rolling bearing 1 is a sealed bearing having a seal 11 for sealing the annular space 10. The seal 11 is arranged at a position closer to the rolling elements 8 than the side surface 6c of the first bearing ring 6 and the side surface 7c of the second bearing ring 7. The seals 11 are arranged on both axial sides of the first bearing ring 6 and the second bearing ring 7. Note that although the seal 11 is exemplified as a contact seal having a core bar and a rubber seal lip bonded to the core bar, a non-contact seal may also be used.

[0041] 2 and 3, the wireless sensor unit 2 has a substrate 12, one or more sensors 13a, 13b mounted on the substrate 12, a wireless communication circuit 14 mounted on the substrate 12, and a power supply 15 that supplies power to the substrate 12, and is a unit assembled so that the entire wireless sensor unit 2 can be detachably attached to the bracket 3 as a unit, without being wired to other communication equipment or an external power supply provided outside the bearing device, by using power from the power supply 15 to detect at least one of a physical quantity and a chemical quantity related to the state of the rolling bearing 1 with the sensors 13a, 13b and outputting the detection result to a predetermined destination with the wireless communication circuit 14. While Fig. 1 shows a screw fastening using a screw member as a configuration for making the sensor 2 detachable, other methods of fastening using an elastic member or magnetic fastening using a magnet may also be used.

[0042] 2 and 4, the bracket 3 is an annular member fixed to the first bearing ring 6. The bracket 3 is joined to one side surface 6c of the first bearing ring 6. The joining means may be any means that does not require machining the shape of the first bearing ring 6 for joining to the bracket 3, and specific examples include welding and adhesive bonding.

[0043] As shown in Figures 5, 6, and 7, the bracket 3 has a cylindrical portion 3a welded or glued in an axially abutting state against the side surface 6c of the first bearing ring 6, and a side plate portion 3b extending from the distal end of the cylindrical portion 3a relative to the first bearing ring 6 toward the second bearing ring 7.

[0044] Since the cylindrical portion 3a and the side plate portion 3b form a ring-shaped body with an L-shaped cross section, the rigidity of the bracket 3 is higher than that of a bracket with a straight cross section, and as a result, the bracket 3 is less likely to vibrate during operation of the rolling bearing 1.

[0045] The bracket 3 is formed from a single metal plate bent into an L-shaped cross section.

[0046] The tubular portion 3a has a cylindrical shape extending in the axial and circumferential directions. The tubular portion 3a abuts against the side surface 6c of the first bearing ring 6 at a position radially shifted from the circumferential edge on the mating surface 6b side toward the second bearing ring 7. The distal end of the tubular portion 3a relative to the first bearing ring 6 is the end opposite the end abutting against the side surface 6c, of the two ends that define the axial length of the tubular portion 3a.

[0047] The side plate portion 3b is an annular plate that extends straight in the radial direction and extends completely around the circumference except for the bent portion where it meets the cylindrical portion 3a. The side plate portion 3b protrudes to a position that faces the annular space 10 of the rolling bearing 1 in the axial direction.

[0048] The radial lengths of the side plate portion 3b and the wireless sensor unit 2 are each longer than the radial length of the side surface 6c of the first bearing ring 6. Because the wireless sensor unit 2 is a highly functional unit equipped with a wireless communication circuit 14, a power source 15, etc., there is a limit to how much the radial length of the wireless sensor unit 2 can be reduced. In particular, when the major dimensions of the rolling bearing 1 are small, the radial length of the wireless sensor unit 2 becomes significantly longer than the radial length of the side surface 6c of the first bearing ring 6. If the radial length of the side surface of the bracket 3 is extended by utilizing the radial range axially opposing the annular space 10, it is possible to provide a sufficient fastening area for the wireless sensor unit 2 and the side plate portion 3b that is radially longer than the side surface 6c of the first bearing ring 6, while preventing the bracket 3 from protruding radially beyond the fitting surface 6b of the first bearing ring 6.

[0049] 6 and 7, a plurality of threaded portions 3c that are threadedly engaged with the threaded member 4 are formed at intervals in the circumferential direction on the side plate portion 3b. The threaded portions 3c are female threaded portions whose screw axes are oriented in the axial direction. The threaded member 4 is a male threaded member.

[0050] As shown in FIGS. 1, 5, and 6, the side surface 6c of the first bearing ring 6 has a radial region A1 that is annular and exposed when viewed from the axial direction. This radial region A1 is the region of the side surface 6c of the first bearing ring 6 from the periphery on the mating surface 6b side to the joint with the cylindrical portion 3a. This radial region A1 can be used to determine the axial position of the rolling bearing 1 by abutting it against another mechanical component (in the illustrated example, the shoulder of the housing 110) in the axial direction. The radial length of this radial region A1 can be set to a size equal to or greater than the dimension corresponding to the shoulder height of the housing as defined in the Japanese Industrial Standards (JIS B1566:2015, "Rolling Bearings - Mounting Dimensions and Fits" - Section "5.2 Shoulder Height and Diameter of Shaft and Housing" for radial bearings), and is, for example, set to 2.25 mm or more, preferably 2.75 mm or more.

[0051] The seal 11 closer to the bracket 3 is disposed between the side plate portion 3b and the plurality of rolling elements 8. Even if the seal 11 tilts toward the bracket 3 due to pressure fluctuations in the annular space 10 that occur during operation of the rolling bearing 1, the axial length of the cylindrical portion 3a provides an axial distance between the side plate portion 3b and the seal 11, so there is no interference between the seal 11 and the side plate portion 3b.

[0052] 1 and 7, the magnetic ring 5 is an annular body having alternating north and south poles in the circumferential direction. The magnetic ring 5 is joined to one of the two side surfaces 7c of the second bearing ring 7 that is closer to the bracket 3. The joining means may be any means that does not require machining the shape of the second bearing ring 7 for joining to the magnetic ring 5, and specific examples include welding or adhesive bonding.

[0053] 5, 6, and 7, the magnetic ring 5 has an annular core 5a welded or glued to the side surface 7c of the second bearing ring 7 in the axial direction, and a magnet portion 5b supported in the radial direction by the circumferential surface of the annular core 5a. The magnet portion 5b is a rubber magnet with many magnetic poles in the circumferential direction.

[0054] 1, 5, and 6, the side surface 7c of the second bearing ring 7 has an annular radial region A2 that is exposed when viewed from the axial direction. This radial region A2 is the region on the side surface 7c of the second bearing ring 7 from the periphery on the mating surface 7b side to the joint with the annular core bar 5a. This radial region A2 can be used to determine the axial position of the rolling bearing 1 by abutting it against another machine component (in the illustrated example, the shoulder of the shaft 100) in the axial direction. As with the above-mentioned radial region A1, the radial length of this radial region A2 can be set to be equal to or greater than the dimension corresponding to the shoulder height of the shaft as defined in the JIS standard, and is set to, for example, 2.25 mm or more, preferably 2.75 mm or more.

[0055] The power supply 15 of the wireless sensor unit 2 shown in Figure 2 consists of a stator that converts the alternating magnetic field generated by the magnetic ring 5 as the magnetic ring 5 and the wireless sensor unit 2 rotate relative to each other in the circumferential direction while the rolling bearing 1 is in operation into AC power.

[0056] As shown in Figures 1, 3, and 8, the wireless sensor unit 2 has a holding member 16 and a protective member 17 for accommodating the substrate 12, and a yoke member 18 and a coil 19 for constructing a power source 15 as a stator using the holding member 16.

[0057] As shown in Figures 2, 5, and 6, the retaining member 16 has an annular side portion 16a including a side surface portion overlapping the side plate portion 3b of the bracket 3 in the axial direction, and first claw pole portions 16b protruding axially from the annular side portion 16a at regular intervals in the circumferential direction toward the opposite side from the side plate portion 3b.

[0058] As shown in Figures 5, 6, and 8, the yoke member 18 has a side peripheral portion 18a that faces a side surface of the annular side portion 16a opposite to the side plate portion 3b at an axial distance, an annular portion 18b that extends in the axial direction from the side peripheral portion 18a to the annular side portion 16a, and second claw pole portions 18c that protrude in the axial direction at regular circumferential intervals from the end of the side peripheral portion 18a that is radially opposite to the annular portion 18b toward the annular side portion 16a.

[0059] The holding member 16 and the yoke member 18 are each made of a magnetic material such as a seamless steel plate, etc. The overall shape of each of the holding member 16 and the yoke member 18 is formed by press working.

[0060] As shown in Figures 3 and 8, the first claw pole portions 16b and the second claw pole portions 18c are arranged in opposite axial directions and alternately arranged in the circumferential direction. A circumferential air gap is formed between the first claw pole portion 16b and the second claw pole portion 18c that are adjacent in the circumferential direction. As shown in Figures 2, 5, and 6, each of the first claw pole portions 16b and each of the second claw pole portions 18c radially faces the magnet portion 5b of the magnetic ring 5 with an air gap therebetween.

[0061] 3, 5, and 6, the coil 19 is disposed circumferentially in the space surrounded by the annular side portion 16a, the peripheral side portion 18a, the annular portion 18b, the first claw pole portion 16b, and the second claw pole portion 18c. Both ends 19a, 19b of the coil 19 are connected to the electrodes 12a, 12b of the substrate 12. Although the coil 19 in the illustrated example is wound around a bobbin, the bobbin may be omitted.

[0062] The magnetic flux emitted from the north pole of the magnetic ring 5 shown in FIGS. 1 and 2 passes, for example, from the first claw pole portion 16b (or the second claw pole portion 18c) to the end of the annular side portion 16a on the second raceway 7 side (or the side circumferential portion 18a), then passes through the annular portion 18b to the side circumferential portion 18a (or the end of the annular side portion 16a on the second raceway 7 side), around the coil 19, and returns to the south pole of the magnetic ring 5 via the adjacent second claw pole portion 18c (or the first claw pole portion 16b). When the north and south poles of the magnetic ring 5 swap positions with the relative rotation of the first raceway 6 and the second raceway 7, the direction of the magnetic flux reverses. The alternating magnetic field thus generated generates an alternating voltage at both ends of the beginning and end of the coil 19. Thus, during operation of the rolling bearing 1, the magnetic ring 5 and the power source 15 serving as the stator function as a radial claw pole generator.

[0063] While this bearing device has been shown as an example in which power supply 15 is configured as the stator of a generator, it is also possible to configure it with a stator and a battery that supplies power to substrate 12 as an emergency power supply, or to configure it with only a battery, or to configure it as a wireless power supply receiving antenna using an electromagnetic induction method, etc. Also, while this bearing device has been shown as an example in which power supply 15 is configured with holding member 16, yoke member 18, and coil 19 so as to function as the stator of a claw-pole generator, it is also possible to change it to a different type.

[0064] 3, 5, and 6, the protective member 17 is an annular cover that forms an internal space between itself and the annular side portion 16a of the holding member 16. As shown in FIGS. 5 and 6, the protective member 17 has a first circumferential portion 17a that abuts against the annular side portion 16a in the axial direction, a side end portion 17b that extends radially from the axial end of the first circumferential portion 17a opposite the annular side portion 16a toward the second bearing ring 7, and a second circumferential portion 17c that extends axially from the end of the side end portion 17b on the second bearing ring 7 side toward the bracket 3. The second circumferential portion 17c of the protective member 17 is fitted into the annular portion 18b of the yoke member 18.

[0065] 3, 5, 6, and 7, the circuit board 12 equipped with the sensors 13a and 13b and the wireless communication circuit 14 is housed between the annular side portion 16a and the protective member 17. Therefore, the circuit board 12 can be protected by the holding member 16 and the protective member 17.

[0066] The protective member 17 is made of resin to enable transmission and reception between the antenna 14a of the wireless communication circuit 14 shown in FIGS. 3 and 5 and the outside. The antenna 14a is disposed in a non-contact state with the protective member 17. The space between the antenna 14a and the protective member 17 is filled with air. The antenna 14a is disposed in an internal space that is not sealed with a conductive material such as metal, so radio waves can be transmitted and received between the antenna 14a and the outside. The protective member 17 may be made of metal, with a portion of the area facing the antenna 14a of the wireless communication circuit 14 made of a non-metal (e.g., resin). Alternatively, the protective member 17 may be omitted and the substrate may be protected by being embedded in a resin sealing material.

[0067] As shown in Figures 3, 5, and 6, the holding member 16 is composed of a single seamless part that serves as both a holder part that supports the substrate 12 and a yoke part such as the first claw pole part 16b that constitutes the power-generating stator, thereby reducing the number of parts.

[0068] As shown in FIGS. 5, 6, and 8, the retaining member 16 has a simple shape in which the annular side portion 16a has a straight cross section and the first claw pole portion 16b and the annular side portion 16a have an L-shaped cross section, thereby achieving the holder function and yoke function described above. This simplifies press working and reduces manufacturing costs.

[0069] The substrate 12 is a printed wiring board. The substrate 12 is formed in the shape of an arc plate that is short in the radial direction and long in the circumferential direction. Sensors 13 a and 13 b, a wireless communication circuit 14, and a power supply circuit 20 are mounted on the surface of the substrate 12 opposite the bracket 3 in the axial direction.

[0070] As shown in Figures 5, 6, and 8, an insulating sheet 21 is sandwiched between the substrate 12 and the annular side portion 16a of the holding member 16. The substrate 12 and the insulating sheet 21 are fixed onto the annular side portion 16a using a plurality of male screw members 22, as shown in Figures 3 and 8. To enable this fixation, the annular side portion 16a is formed with a plurality of female screw holes 16c corresponding to the male screw members 22, as shown in Figure 8, and the substrate 12 and the insulating sheet 21 are formed with a plurality of through holes 12c, 21a corresponding to the male screw members 22, respectively.

[0071] Since the threaded shafts of the male screw members 22 extend beyond the annular side portion 16a toward the opposite side of the substrate 12, the side plate portion 3b of the bracket 3 has a plurality of voids 3d formed therein to accommodate the extending portions of the male screw members 22, as shown in Figures 4 and 7. This makes it possible to reduce the axial width of the wireless sensor unit 2 by setting the thickness of the annular side portion 16a shown in Figures 5 and 6 to, for example, 1.5 mm or less, while also reliably fastening the substrate 12 to the annular side portion 16a with screws. If male screw members that do not interfere with the side plate portion 3b of the bracket 3 can be used, the formation of the voids 3d can be omitted.

[0072] As shown in Figures 2, 6 and 7, in order to pass the screw member 4 from the protective member 17 to the threaded portion 3c of the side plate portion 3b, the protective member 17, the substrate 12, the insulating sheet 21 and the holding member 16 are each formed with a plurality of screw-through portions 17d, 12d, 21b and 16d as shown in Figures 6 and 8.

[0073] The entrance of each screw-through portion 17d of the protective member 17 is formed in the shape of a counterbore hole. The head of the screw 4 is completely inserted into the screw-through portion 17d, as shown in Figures 2 and 6 .

[0074] 6, each screw-through portion 17d of the protective member 17 is provided so as to be able to press the substrate 12 in the axial direction so that the fastening force of the screw member 4 is applied to the annular side portion 16a of the holding member 16 via the protective member 17 and the substrate 12. The position at which each screw-through portion 17d presses the substrate 12 is set at a position away from the circuit constructed on the substrate 12 so as not to damage the circuit.

[0075] The sensors 13a and 13b shown in Figure 3 each consist of a circuit that converts the aforementioned physical or chemical quantities into an electrical signal. Sensor 13a is an acceleration sensor for monitoring the vibration of rolling bearing 1 (hereinafter, sensor 13a will be referred to as "vibration sensor 13a" as appropriate). Sensor 13b is a temperature sensor for monitoring the temperature of rolling bearing 1 (hereinafter, sensor 13b will be referred to as "temperature sensor 13b" as appropriate). Electronic components including a temperature sensor and an acceleration sensor may be mounted on substrate 12. Furthermore, sensors other than vibration sensor 13a and temperature sensor 13b may be added to wireless sensor unit 2.

[0076] The vibration sensor 13a is made up of a circuit that detects vibrations generated in the rolling bearing 1. For example, an acceleration sensor or an AE (Acoustic Emission) sensor can be used as the vibration sensor 13a. If an acceleration sensor that can detect acceleration in three mutually orthogonal axial directions is used, it is possible to detect radial and axial accelerations in order to monitor the vibration of the rolling bearing 1. If an AE sensor is used, it is possible to detect elastic waves (AE waves) that are emitted when sound is generated when a part of an object, such as a component of the rolling bearing 1, is deformed or damaged, or when an impact is applied.

[0077] The temperature sensor 13b comprises a circuit that converts temperature into an electrical signal. The rolling bearing 1 generates heat as it rotates. One of the main causes of this heat is heat generated at the contact point between the rolling elements 8 and the raceway surface 6a of the first raceway ring 6. The faster this heat reaches the temperature sensor 13b, the faster and more accurately temperature changes in the first raceway ring 6 can be detected. Therefore, a through-hole for sensor placement may be formed in the substrate 12, and the temperature sensor 13b may be embedded in this through-hole and brought into contact with the annular side portion 16a.

[0078] Furthermore, in order to reduce the heat conduction path length from the raceway surface 6a of the first race 6 to the temperature sensor 13b and to reduce the axial length of this bearing device, it is desirable to make the distance between the side surface 6c of the first race 6 and the side plate 3b as small as possible. For example, the axial distance from the side surface 6c of the first race 6 to the side plate 3b of the bracket 3 (the surface farther from the side surface 6c) should be set to 10 mm or less (preferably 5 mm or less).

[0079] In addition, in order to increase the cross-sectional area of ​​the heat conduction path that runs directly axially from the bracket 3 shown in Figures 5 and 6 to the substrate 12 via the holding member 16, it is preferable that the entire plate surface of the substrate 12 faces the bracket 3 and the holding member 16 in the axial direction.

[0080] The wireless communication circuit 14 shown in Figures 3 and 5 is a communication circuit that converts predetermined information, such as the detection results of the sensors 13a and 13b, into radio waves and radiates the radio waves from the antenna 14a. The wireless communication circuit 14 complies with a predetermined communication protocol. The wireless communication circuit 14 is a module that includes the antenna 14a. The antenna 14a is a pattern antenna.

[0081] The power supply circuit 20 is a circuit that converts AC power generated by the power supply 15 as the magnetic ring 5 rotates into DC power used by the substrate 12 (sensors 13a, 13b, wireless communication circuit 14).

[0082] The manufacturing process of this bearing device can be roughly divided into a bearing unit manufacturing stage in which assembly is carried out around the rolling bearing 1, and a sensor unit manufacturing stage in which assembly is carried out around the holding member 16.

[0083] In the bearing unit manufacturing stage, a bracket fixing process is performed in which the bracket 3 is joined to the side surface 6c of the first raceway 6 of the rolling bearing 1 shown in Figure 4, and a magnetic ring fixing process is performed in which the magnetic ring 5 is joined to the side surface 7c of the second raceway 7, thereby forming the rolling bearing 1, the bracket 3, and the magnetic ring 5 into a unit (hereinafter referred to as the "bearing unit").

[0084] Each of the bracket fixing process and magnetic ring fixing process is carried out using a jig (not shown) to ensure that the coaxiality between the bracket 3 and the first raceway 6, and the coaxiality between the magnetic ring 5 and the second raceway 7 are at or above a specified level during joining.

[0085] 5 and 6 show examples in which welding is used as a joining method in the bracket fixing process and the magnetic ring fixing process. The weld W1 between the side surface 6c of the first bearing ring 6 and the cylindrical portion 3a of the bracket 3 and the weld W2 between the side surface 7c of the second bearing ring 7 and the annular core metal 5a of the magnetic ring 5 are indicated by black areas. Examples of welding methods that can be used include laser welding. To reduce thermal distortion of the first bearing ring 6 and the second bearing ring 7, it is preferable to limit the welds W1 and W2 to a few circumferentially spaced locations rather than providing them around the entire circumference. For example, spot welding at three to eight locations may be used. If the welds W1 and W2 extend significantly beyond the corresponding side surface 6c of the first bearing ring 6 or the corresponding side surface 7c of the second bearing ring 7, the radial length of the corresponding radial region A1 or A2 will be shortened accordingly. To prevent this protrusion, a chamfer may be formed at the welding location of the corresponding cylindrical portion 3a or annular core metal 5a, and the welded portion may be accommodated in the gap between the chamfer and the corresponding side surface 6c or 7c.

[0086] In the sensor unit manufacturing stage, a stator assembly process is performed in which coil 19 is positioned between annular side portion 16a of holding member 16 and side peripheral portion 18a of yoke member 18, as shown in Figure 8, and holding member 16 and yoke member 18 are combined to form a unit (hereinafter referred to as the "first intermediate unit").

[0087] In the stator assembly process, as shown in Figures 5, 6, and 8, a yoke member 18 having axial protrusions 18d formed on the annular portion 18b and a retaining member 16 having spigots 16e formed on the annular side portion 16a in a position corresponding to the protrusions 18d are used, and the spigots 16e and the protrusions 18d are fitted together and secured. The fastening method may be press-fitting the spigots 16e and the protrusions 18d, adhesive bonding, laser welding, or a combination of these. The fitting of the spigots 16e and the protrusions 18d ensures that the retaining member 16 and the yoke member 18 are coaxial. Furthermore, the first claw pole portions 16b and the second claw pole portions 18c are alternately arranged with a circumferential gap at a predetermined phase. This allows the retaining member 16 and the yoke member 18 to be properly assembled without using a jig. Preferably, the spigots 16e on the annular side portion 16a and the protrusions 18d on the yoke member 18 are each formed in three or more locations. It is also possible to omit the spigots 16e and protrusions 18d. In this case, after the holding member and the yoke member are coaxially aligned and phase-aligned using a jig (not shown), the butting portions of the annular portion of the yoke member and the annular side portion of the holding member may be fixed by adhesive bonding, laser welding from the outside of the annular portion, or a combination of these methods.

[0088] By performing a substrate fixing process in which the substrate 12 is attached to the annular side portion 16a of the first intermediate unit as shown in Figure 3, the substrate 12 and the first intermediate unit are unitized (hereinafter referred to as the ``second intermediate unit'').

[0089] 8, the substrate 12 on which the sensors 13a and 13b, the wireless communication circuit 14, and the power supply circuit 20 are mounted is used, an insulating sheet 21 is sandwiched between the substrate 12 and the annular side portion 16a, and a plurality of male screw members 22 are threaded through corresponding through holes 12c of the substrate 12 and through holes 21a of the insulating sheet 21 and into the female screw holes 16c of the annular side portion 16a, thereby fixing the substrate 12 and the insulating sheet 21 to the annular side portion 16a as shown in FIGS. 3, 5, and 6. Note that instead of fixing the substrate 12 to the holding member 16 with screws, the substrate 12 can also be fixed to the holding member 16 by adhesion using an adhesive, an adhesive sheet, or the like, or by a combination of screwing and adhesion.

[0090] As shown in FIG. 3, a soldering step is carried out to connect both ends 19a, 19b of the coil 19 to the electrode portions 12a, 12b of the substrate 12 of the second intermediate unit.

[0091] After the soldering step, a covering step is performed in which the protective member 17 is fixed to the second intermediate unit, thereby completing the assembly of the wireless sensor unit 2 as shown in FIG.

[0092] In the covering process, as shown in Figures 5 and 6, the first circumferential portion 17a of the protective member 17 is bonded to the annular side portion 16a of the holding member 16, and the second circumferential portion 17c is bonded to the annular portion 18b of the yoke member 18, thereby fixing the protective member 17. Here, by fitting the second circumferential portion 17c to the annular portion 18b, the protective member 17 can be appropriately positioned radially relative to the holding member 16 via the yoke member 18. Note that the protective member 17 may also employ a second intermediate unit (at least one of the annular side portion 16a, the substrate 12, and the yoke member 18) having meshing portions or markers to facilitate the phase alignment between the threading portions 17d, 12d, 21b, and 16d, and between the female threaded hole portion 16c and the through holes 12c and 21a, as shown in Figure 8.

[0093] As shown in FIG. 7, the assembly of the bearing device shown in FIGS. 1 and 2 is completed by carrying out a fastening process for fixing the wireless sensor unit 2 to the bracket 3 of the bearing unit described above.

[0094] In the fastening process, the wireless sensor unit 2 is fastened to the side plate portion 3b by passing a plurality of screw members 4 through the corresponding screw-through portions 17d, 12d, 21b, 16d as shown in FIG. 6 and screwing them into the threaded portions 3c of the side plate portion 3b.

[0095] The covering step may be omitted, and in the fastening step, the protective member 17 and the annular side portion 16a may be fastened together to the side plate portion 3b with a plurality of screws 4, thereby simultaneously completing the assembly of the wireless sensor unit 2 and the fixation to the bracket 3. In this case, if the first circumferential portion 17a of the protective member 17 presses the annular side portion 16a in the axial direction and the second circumferential portion 17c presses the annular side portion 16a in the axial direction via the substrate 12, it is possible to bring the annular side portion 16a and the side plate portion 3b into full contact with each other. In this case, since it is not possible to seal the gaps between the first circumferential portion 17a and the annular side portion 16a and between the second circumferential portion 17c and the annular portion 18b of the yoke member 18 with adhesive, the fastening step may be performed with a sealant applied to seal the gaps in order to ensure airtightness.

[0096] Furthermore, when the wireless sensor unit 2 is fastened to the bracket 3, the side plate portion 3b completely covers each of the spigot portions 16e of the annular side portion 16a of the holding member 16, making it less likely for water, oil, etc. to penetrate between each of the spigot portions 16e and the protrusion 18d.

[0097] In this way, in this bearing device (see Figures 4, 5, 6 and 7), the bracket 3 is joined to one of the two side surfaces 6c that define the width of the first raceway 6, and the wireless sensor unit 2 is attached to the bracket 3, so that while it is possible to detect the condition of the rolling bearing 1 with the wireless sensor unit 2, there is no need to use a special first raceway with a stepped portion machined for the wireless sensor unit 2, and the procurement costs of the rolling bearing 1 can be reduced.

[0098] As shown in FIG. 1 , if the rolling bearing 1 of this bearing device, which is mounted between the shaft 100 and the housing 110, is damaged and needs to be replaced, the ends of the screw members 4 are exposed on the side of the wireless sensor unit 2 fastened to the bracket 3 attached to the rolling bearing 1. Therefore, the screw members 4 can be removed from the bracket 3 using a screwdriver, and the wireless sensor unit 2 can be removed from the bracket 3. Since no particular load is applied to the wireless sensor unit 2 when removing the screw members 4, there is no risk of damaging the wireless sensor unit 2. Because the wireless sensor unit 2 is fastened to the bracket 3 in a non-destructive and detachable manner using the screw members 4, the wireless sensor unit 2 attached to the first race 6 can be reused when replacing the rolling bearing 1. The procurement cost of a new bracket 3 and rolling bearing 1 with a magnetic ring 5 is lower than the procurement cost of a high-performance wireless sensor unit 2 equipped with a wireless communication circuit 14, a power supply 15, etc. Therefore, compared to replacing the entire bearing device, it is possible to reduce the running costs of this bearing device.

[0099] This bearing device (see Figures 1 and 3) is as described above and comprises a rolling bearing 1 having a first raceway 6, a second raceway 7, and a plurality of rolling elements 8 arranged between the first raceway 6 and the second raceway 7, a substrate 12, a wireless sensor unit 2 having one or more sensors 13a, 13b and a wireless communication circuit 14 mounted on the substrate 12, and a power source 15 for supplying power to the substrate 12, and a bracket 3 fixed to the first raceway 6, whereby the wireless sensor unit 2 is configured to be detachable from the bracket 3 and the bracket 3 is joined to one of the two side surfaces 6c which define the width of the first raceway 6, so that while it is possible to detect the condition of the rolling bearing 1 with the wireless sensor unit 2, the aforementioned procurement costs and running costs can be reduced and the device can be provided as an economical bearing device.

[0100] In addition, in this bearing device (see Figures 5 and 6), the bracket 3 is welded or glued to the side surface 6c of the first bearing ring 6, so that the bracket 3 can be fixed to the side surface 6c of the first bearing ring 6.

[0101] Furthermore, in this bearing device (see Figures 1, 5 and 6), the bracket 3 has a side plate portion 3b that faces axially the annular space 10 formed between the first raceway 6 and the second raceway 7, and the wireless sensor unit 2 is fastened to the side plate portion 3b. As a result, the radial length of the side surface of the bracket 3 can be expanded by utilizing the radial range that faces axially the annular space 10 of the rolling bearing 1, and the wireless sensor unit 2, which is radially longer than the side surface 6c of the first raceway 6, can be fastened to the bracket 3.

[0102] Furthermore, this bearing device has a cylindrical portion 3a that is welded or glued so that the bracket 3 is in abutting position against the side surface 6c of the first raceway 6, and the side plate portion 3b is continuous with the cylindrical portion 3a and extends from the radially outer side to the radially inner side, so that the cylindrical portion 3a and side plate portion 3b of the bracket 3 form a ring-shaped body with an L-shaped cross section.This makes it possible to increase the rigidity of the bracket 3 compared to using a bracket with a straight cross section, and ultimately makes the bracket 3 less likely to vibrate, making it easier to achieve stable detection by the sensors 13a, 13b of the wireless sensor unit 2 fastened to the bracket 3, especially the vibration sensor 13a.

[0103] Furthermore, in this bearing device, the rolling bearing 1 is a bearing equipped with a seal 11, and the seal 11 is disposed between the side plate portion 3b of the bracket 3 and the plurality of rolling elements 8, so that a distance is provided between the side plate portion 3b and the seal 11 equal to the axial length of the cylindrical portion 3a of the bracket 3 joined to the side surface 6c of the first raceway ring 6, thereby preventing interference between the bracket 3 and the seal 11. For this reason, even if a general sealed bearing is used as the rolling bearing 1, it is possible to ensure similar sealing performance.

[0104] Furthermore, this bearing device has a radial region A1 in the shape of a ring where the side surface 6c of the first raceway 6 is exposed when viewed from the axial direction, and this radial region A1 can be abutted against another mechanical part (in the illustrated example, the shoulder of the housing 110) in the axial direction to determine the axial position of the rolling bearing 1.

[0105] This bearing device (see Figures 1 and 7) also includes a magnetic ring 5 fixed to the second raceway 7 and having alternating north and south poles in the circumferential direction, and a power source 15 having a stator that converts the alternating magnetic field of the magnetic ring 5 that occurs when the first raceway 6 and the second raceway 7 rotate relative to each other into AC power, and the second raceway 7 has two side surfaces 7c that define the width of the second raceway 7, and the magnetic ring 5 is joined to one of the side surfaces 7c of the second raceway 7, so that while the rolling bearing 1 is in operation, the stator can be used as the power source 15 to supply AC power to the substrate 12, and there is no need to use a special second raceway with a stepped portion machined for the magnetic ring 5.

[0106] In addition, in this bearing device (see Figures 1, 5, 6, and 7), the magnetic ring 5 is welded or glued to the side surface 7c of the second bearing ring 7, so that the magnetic ring 5 can be fixed to the side surface 7c of the second bearing ring 7.

[0107] Furthermore, this bearing device has a radial region A2 in an annular shape where the side surface 7c of the second raceway 7 is exposed when viewed from the axial direction, and this annular radial region A2 can be abutted axially against another mechanical part (in the illustrated example, the shoulder of the shaft 100) to determine the axial position of the rolling bearing 1.

[0108] When the wireless communication circuit 14 is configured as a single electronic component, such as a wireless module, as in this bearing device, transmission and reception can be performed using the antenna 14a attached to the wireless module. Radio waves transmitted and received between the antenna 14a, housed in an internal space surrounded by a magnetic holding member 16 and a resin protective member 17, and the outside world pass through the protective member 17. The wavelength of the radio waves is shortened by the dielectric properties of the resin protective member 17. If the wireless communication performance is significantly degraded due to the aforementioned wavelength shortening, countermeasures are necessary. One such countermeasure is to mount another antenna suitable for the bandwidth after the shortened wavelength on the wireless sensor unit and connect it to the circuit board for use in wireless communication. A simple countermeasure is to simply form a hole in the protective member for exposing the antenna. An example of such a bearing device according to a second embodiment is shown in Figures 9 and 10. Note that differences from the first embodiment will be discussed here, and the same reference numerals will be used for corresponding components.

[0109] A hole 17e is formed in the side end 17b of the protective member 17 according to the second embodiment so as to expose the entire antenna 14a of the wireless communication circuit 14 in the axial direction. Radio waves transmitted and received through the hole 17e between the antenna 14a and the outside of the wireless sensor unit 2 do not pass through the protective member 17 and are therefore maintained in a band suitable for the communication protocol to which the wireless communication circuit 14 conforms. This prevents a decrease in the performance of wireless communication using the antenna 14a.

[0110] As described above, the bearing device according to the second embodiment has a retaining member 16 in which the wireless sensor unit 2 is axially stacked on the bracket 3, and a protective member 17 combined with the retaining member 16, the circuit board 12 is housed between the retaining member 16 and the protective member 17, and the wireless communication circuit 14 has the antenna 14a exposed from a hole 17e formed in the protective member 17. This makes it possible to protect the circuit board 12 with the retaining member 16 and the protective member 17, while the antenna is exposed from the hole 17e in the protective member 17, thereby suppressing a decrease in wireless communication performance due to the dielectric constant of the protective member 17. Therefore, there is no need to add another antenna in addition to the antenna 14a attached to the wireless module.

[0111] If a gap between the periphery of the antenna 14a and the protective member 17 becomes a problem, the gap can be filled with a resin sealant. Also, the surface of the antenna 14a can be thinly coated with a liquid repellent agent to protect the antenna 14a from condensation.

[0112] In the above-described embodiments, the first raceway ring is the outer raceway / fixed raceway and the second raceway ring is the inner raceway / rotating raceway (i.e., a rolling bearing used with an inner raceway rotating), but the present invention can also be applied to a case where the first raceway ring is the inner raceway and the second raceway ring is the outer raceway. In this case, the radial relationship between the inside and outside of the bracket, wireless sensor unit, and magnetic ring in the above-described embodiments can be reversed, and the bracket can be fixed to the first raceway ring as the inner raceway, with the bracket joined to the side of the inner raceway.

[0113] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0114] REFERENCE SIGNS LIST 1 Rolling bearing 2 Wireless sensor unit 3 Bracket 3a Cylindrical portion 3b Side plate portion 3c Threaded portion 4 Threaded member 5 Magnetic ring 5a Annular core 5b Magnet portion 6 First bearing ring 6c Side surface 7 Second bearing ring 7c Side surface 8 Rolling element 10 Annular space 11 Seal 12 Substrate 13a, 13b Sensor 14 Wireless communication circuit 14a Antenna 15 Power supply 16 Holding member 16a Annular side portion 16b First claw pole portion 17 Protective member 17e Hole 18 Yoke member 18a Side circumferential portion 18b Annular portion 18c Second claw pole portion 19 Coil A1, A2 Radial region W1, W2 Welded portion

Claims

1. A bearing device comprising: a rolling bearing having a first raceway, a second raceway, and a plurality of rolling elements arranged between the first raceway and the second raceway; a wireless sensor unit having a substrate, one or more sensors and a wireless communication circuit mounted on the substrate, and a power source for supplying power to the substrate; and a bracket fixed to the first raceway, wherein the wireless sensor unit is configured to be detachable from the bracket, and the bracket is joined to one of two sides that define the width of the first raceway.

2. A bearing device according to claim 1, wherein said bracket is welded or bonded to said side surface of said first bearing ring.

3. A bearing device as described in claim 2, wherein the bracket has a side plate portion that faces axially toward the annular space formed between the first and second raceways, and the wireless sensor unit is fastened to the side plate portion.

4. A bearing device as set forth in claim 3, wherein the bracket has a cylindrical portion welded or glued so as to abut against the side surface of the first bearing ring, and the side plate portion is continuous with the cylindrical portion and extends from the radially outer side to the radially inner side.

5. A bearing device according to claim 4, wherein said rolling bearing is a sealed bearing, said seal being disposed between said side plate portion of said bracket and said plurality of rolling elements.

6. A bearing device according to any one of claims 1 to 5, wherein the side surface of the first bearing ring has an annular radial region that is exposed when viewed from the axial direction.

7. A bearing device according to any one of claims 1 to 5, further comprising a magnetic ring fixed to said second raceway and having alternating north and south poles in the circumferential direction, said power source having a stator for converting the alternating magnetic field of said magnetic ring caused by relative rotation between said first raceway and said second raceway into AC power, said second raceway having two side surfaces which define the width of said second raceway, and said magnetic ring being joined to one of said side surfaces of said second raceway.

8. A bearing assembly according to claim 7, wherein said magnetic ring is welded or glued to said side surface of said second raceway ring.

9. A bearing device according to claim 7, wherein the side surface of the second bearing ring has an annular radial region that is exposed when viewed from the axial direction.

10. A bearing device as claimed in any one of claims 1 to 5, wherein the wireless sensor unit has a holding member axially stacked on the bracket and a protective member combined with the holding member, the circuit board is housed between the holding member and the protective member, and the wireless communication circuit has an antenna exposed from a hole formed in the protective member.

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