Bearing with rotation sensor

Abstract

This bearing with a rotation sensor is configured such that a sensor housing (21) of a rotation sensor (20) has a protrusion (27) projecting at a position facing a magnetic sensor element (37) in the axial direction, and the magnetic sensor element (37) is axially positioned relative to the sensor housing (21) by abutment with the protrusion (27) in the axial direction.

Description

Bearing with rotation sensor

[0001] The present invention relates to a bearing with a rotation sensor that detects the relative rotational movement of an inner ring with respect to an outer ring of a rolling bearing.

[0002] For reducing the size and weight of machinery such as industrial robots, a bearing with an integrated rotation sensor and rolling bearing is sometimes employed (e.g., Patent Document 1). The rotation sensor detects the relative rotational movement of the inner ring with respect to the outer ring of the rolling bearing. By integrating the rotation sensor and the rolling bearing, it is possible to eliminate the labor of positioning and attaching the rotation sensor after mounting the rolling bearing to the device, which facilitates the work of incorporating the bearing into the device. In addition, these configurations can also be simplified.

[0003] The bearing with rotation sensor disclosed in Patent Document 1 includes an outer ring, a rolling bearing having an inner ring and a plurality of rolling elements, and a rotation sensor that detects the relative rotational movement of the inner ring with respect to the outer ring. The rotation sensor is a magnetic type, and includes a sensor housing, a sensor substrate attached to the sensor housing, and a magnetic ring attached to the inner ring. The sensor substrate includes a substrate and a magnetic sensor element attached to the substrate. The magnetic sensor element is provided opposing the magnetic ring.

[0004] Japanese Unexamined Patent Publication No. 2022-149362

[0005] Conventionally, regarding the axial positional relationship between the magnetically sensitive part of the radially opposing magnetic sensor element and the magnetic field of the magnetic ring, since the width of the magnetic track of the magnetic ring was large, it was not necessary to set this positional relationship very strictly. When the sensor substrate is disposed in the sensor housing in the bearing with rotation sensor of Patent Document 1, the sensor substrate is positioned axially relative to the sensor housing by abutting the edge of the substrate against the sensor housing in the axial direction, and no particular problem has occurred.

[0006] However, in recent years, configurations that narrow the track width of the magnetic ring, such as by providing double rows of magnetic tracks on the magnetic ring, have been adopted, and there is a need to precisely determine the axial positional relationship between the magnetic sensor element and the magnetic track.

[0007] The bearing with a rotation sensor described in Patent Document 1 has limitations in the dimensional accuracy of the edges of the substrate cut from the panel during mass production, making it difficult to precisely determine the axial positional relationship between the magnetic sensor element and the magnetic track on the substrate. Therefore, there is a need for a bearing with a rotation sensor that can meet the above needs.

[0008] The problem that this invention aims to solve is to achieve high-precision axial positioning of a magnetic sensor element relative to a sensor housing.

[0009] In order to solve the above problems, this invention employs a bearing with a rotation sensor having the following configuration: [Configuration 1] A rolling bearing comprising a stationary ring, a rotating ring and a plurality of rolling elements, and a rotation sensor for detecting the relative rotational motion of the rotating ring with respect to the stationary ring, wherein the rotation sensor comprises a sensor housing attached to the stationary ring, a sensor substrate attached to the sensor housing, and a magnetic ring attached to the rotating ring, wherein the sensor substrate comprises a substrate and a magnetic sensor element attached to the substrate, and the magnetic sensor element is radially opposite to the magnetic ring, wherein the magnetic sensor element is surface-mounted on the substrate, and the sensor housing comprises a substrate guide portion into which the substrate is inserted in the axial direction and a protrusion projecting at a position axially opposite to the magnetic sensor element, wherein the magnetic sensor element is axially positioned with respect to the sensor housing by axial contact with the protrusion.

[0010] By adopting this configuration 1, the magnetic sensor element is positioned by contacting the protrusion of the sensor housing. This allows for highly accurate axial positioning of the magnetic sensor element relative to the sensor housing, without being affected by errors in the cut shape of the substrate edge or errors in the mounting position of the magnetic sensor element on the substrate.

[0011] [Configuration 2] The bearing with a rotary sensor according to Configuration 1, wherein the substrate guide portion includes a substrate receiving surface that supports the plate surface of the substrate, and the sensor substrate is positioned radially relative to the sensor housing by being fastened so that the plate surface and the substrate receiving surface are in contact with each other.

[0012] By adopting this configuration 2, the board surface of the substrate and the substrate receiving surface are fastened together so that they are in contact and positioned radially, thus enabling accurate radial positioning of the magnetic sensor element relative to the sensor housing.

[0013] [Configuration 3] The bearing with a rotary sensor according to Configuration 2, wherein an insert fitting having an internal thread is fitted into the substrate, a through hole corresponding to the position of the insert fitting is formed in the sensor housing, the sensor housing has a bolt that is threaded through the through hole and screwed into the insert fitting, and the plate surface and the substrate receiving surface come into contact with each other by the threading of the bolt and the insert fitting, and the sensor substrate is fixed to the sensor housing.

[0014] By adopting this configuration 3, the insert fitting fitted into the substrate and the bolt passed through the through hole in the sensor housing are screwed together to fasten the substrate receiving surface and the substrate surface, and the axial position of the substrate relative to the substrate guide is also fixed, so that the sensor substrate can be reliably fixed in the appropriate position relative to the sensor housing.

[0015] [Configuration 4] A bearing with a rotation sensor according to any one of Configurations 1 to 3, wherein the fixed ring has a circumferential groove extending around its entire circumference, the sensor housing has a ring member including the substrate guide portion and the protrusion portion, and a fixing part connecting the ring member to the fixed ring, the fixing part has a crimping fitting including a plurality of claws provided at a plurality of locations in the circumferential direction and extending toward the ring member, and an annular rubber portion provided on the outer circumference of the crimping fitting, the ring member is fixed to the crimping fitting by crimping the plurality of claws toward the ring member, and the crimping fitting is fixed to the fixed ring by fitting the rubber portion into the circumferential groove of the fixed ring.

[0016] By adopting this configuration 4, the rubber portion of the fixing component is easily fitted into the circumferential groove of the fixed ring, and the fixing component is easily crimped onto the ring member, and no machining is required for these operations.

[0017] [Configuration 5] The bearing with a rotation sensor according to any one of Configurations 1 to 4, wherein the magnetic ring has annular magnets that are magnetized alternately in opposite polarities in the circumferential direction, and the magnets are arranged in double rows in the axial direction on the magnetic ring.

[0018] By adopting this configuration 5, the sensor board can detect the rotation angle, rotation speed, rotation direction, etc., with high precision based on the changes in the magnetic fields of each of the double-row magnets.

[0019] The bearing with a rotation sensor of this invention, by employing the above configuration 1, can achieve high precision in the axial positioning of the magnetic sensor element relative to the sensor housing.

[0020] Figure 1 shows a cross-sectional view of a bearing with a rotation sensor according to an embodiment of this invention. Figure 1 shows a cross-sectional view along line II-II. Figure 2 shows a side view showing the state without the magnetic ring attached. Figure 1 shows the state in which the fixing part is pressed into the circumferential groove of the outer ring with a jig. Figure 4 shows the state in which the sensor housing is inserted into the outer ring. Figure 5 shows the state in which the crimping fitting is crimped with a jig. A modified example of the crimping method of the crimping fitting in Figure 5 is shown corresponding to Figure 6. A modified example of the crimping method of the crimping fitting in Figure 5 is shown corresponding to Figure 6. Figure 1 shows the state in which the magnetic ring is pressed into the inner ring with a jig. A modified example of the crimping method of the magnetic ring in Figure 1 is shown corresponding to Figure 9. A modified example of the bearing with a rotation sensor in Figure 1 is shown corresponding to Figure 1.

[0021] An embodiment of this invention will be described based on the attached drawings. Figure 1 shows a bearing with a rotation sensor according to an embodiment of this invention. This bearing with a rotation sensor is used, for example, to detect the rotation angle and rotation speed of relative rotation between two members that rotate relative to each other. The bearing with a rotation sensor comprises a rolling bearing 1 and a magnetic rotation sensor 20.

[0022] As shown in Figure 1, the rolling bearing 1 comprises a stationary ring 2, a stationary ring 3, a plurality of rolling elements 4, a cage 5 that holds these rolling elements 4, and a seal 6 attached to the stationary ring 2. The stationary ring 2 and the stationary ring 3 each consist of a single, seamless raceway ring. In this embodiment, the stationary ring 2 is the outer ring, and the stationary ring 3 is the inner ring. The rolling elements 4 are balls in this case.

[0023] This rolling bearing 1 is a grease-filled bearing in which grease is sealed in the bearing space between the fixed wheel 2 and the stationary wheel 3. The grease is sealed before the rotation sensor 20 is installed.

[0024] Here, the direction along the bearing's central axis is called the axial direction, the direction perpendicular to the bearing's central axis is called the radial direction, and the direction along the circumference around the bearing's central axis is called the circumferential direction. In Figure 1, the axial direction corresponds to the left-right direction in the figure, and the radial direction corresponds to the up-down direction in the figure. The central axes of the fixed wheel 2 and the stationary wheel 3 coincide with the bearing's central axis. Hereafter, one side of the axial direction will be referred to as the right side of the figure, and the other side of the axial direction as the left side of the figure.

[0025] As shown in Figure 1, outer ring width surfaces 7 are formed on both axial sides of the fixed wheel 2. The outer ring width surfaces 7 are planes perpendicular to the axial direction. On the inner circumference of the fixed wheel 2, there are outer ring raceway grooves 8 on which the rolling elements 4 roll, and cylindrical surfaces 9 with a constant inner diameter adjacent to the outer ring raceway grooves 8. The outer ring raceway grooves 8 are arc grooves with a concave arc-shaped cross-section along the surface of the rolling elements 4, and extend around the entire circumference in the axial center of the inner circumference of the fixed wheel 2. Between each cylindrical surface 9 and the corresponding outer ring width surface 7, circumferential grooves 10 extend around the entire circumference.

[0026] Inner ring width surfaces 11 are formed on both axial sides of the stationary wheel 3. The inner ring width surfaces 11 are planes perpendicular to the axial direction. On the outer circumference of the stationary wheel 3, an inner ring raceway groove 12 on which the rolling elements 4 roll, and a cylindrical surface 13 with a constant outer diameter adjacent to the inner ring raceway groove 12 are formed. The inner ring raceway groove 12 is an arc groove with a concave arc-shaped cross-section along the surface of the rolling elements 4, and extends around the entire circumference in the axial direction from the axial center of the outer circumference of the stationary wheel 3. Of the cylindrical surfaces 13 on both axial sides, a seal groove 14 is formed around the entire circumference between the cylindrical surface 13 on the other axial side (left side in the figure) and the inner ring width surface 11 on the other axial side.

[0027] The width length of the stationary wheel 2 (the length between the outer ring width surfaces 7 on both sides in the axial direction) is set to the same dimension as the width length of the stationary wheel 3 (the length between the inner ring width surfaces 11 on both sides in the axial direction). The stationary wheel 2, stationary wheel 3, and rolling elements 4 are all made of metal (for example, high- and medium-carbon alloy steel, carburized steel, bearing steel, etc.).

[0028] Although a ball bearing was used as an example of rolling bearing 1, it is possible to change the rolling bearing to a roller bearing. Also, although a deep groove ball bearing was used as an example of the ball bearing, it is possible to change it to an angular contact ball bearing.

[0029] The stationary wheel 2 is used as a stationary wheel by fitting its outer circumferential surface to a stationary part of the machinery, such as a housing, relative to the rotating shaft. The stationary wheel 3 is used as a rotating wheel by fitting its inner circumferential surface to the rotating shaft of the machinery. Examples of machinery include rotating electrical equipment and reduction gear drive units used in the joints of robots.

[0030] As shown in Figure 1, the retainer 5 is a crown-type retainer having claw portions 15 that protrude in the axial direction. Between adjacent claw portions 15 in the circumferential direction, hemispherical pockets for housing the balls are formed. The retainer 5 holds the rolling elements 4 at regular intervals in the circumferential direction by holding the balls in each pocket. The retainer 5 is made of resin. As the resin, an injection-molded product of a thermoplastic resin such as polyamide (PA) reinforced with glass fibers can be used. The retainer 5 may also be a retainer made of a press-molded thin metal sheet. Alternatively, it may be a cage-type retainer.

[0031] The seal 6 is attached to the other axial end (left side in Figure 1) of the annular bearing internal space formed between the fixed ring 2 and the stationary ring 3. The seal 6 consists of a core metal 16 made of a press-formed thin sheet and an oil-resistant rubber 17 that is vulcanized and bonded to the core metal 16. The rubber 17 has an outer circumference 18 that is locked in the circumferential groove 10 and a lip portion 19 that slides against the seal groove 14. The lip portion 19 and the seal groove 14 work together to prevent grease leakage from the bearing internal space and to prevent foreign matter from entering the bearing internal space.

[0032] Examples of rubber 17 include nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), fluororubber (FKM), and acrylic rubber (ACM). The material and manufacturing method of the seal 6 are not particularly limited. For example, a seal made by applying a rust-preventive coating such as tin plating or zinc plating to a press-formed thin metal sheet, or a seal made by press-forming a plated steel sheet that has undergone a surface treatment, can be used. Although a contact seal has been exemplified as the seal 6, a non-contact seal can also be used. For example, the lip portion 19 may not contact the seal groove 14 and may have a gap in the radial direction.

[0033] As shown in Figures 1 and 2, the rotation sensor 20 includes a sensor housing 21 attached to the stationary wheel 2, a sensor substrate 22 attached to the sensor housing 21, and a magnetic ring 23 attached to the stationary wheel 3. The rotation sensor 20 detects the relative rotational motion of the stationary wheel 3 with respect to the stationary wheel 2.

[0034] The sensor housing 21 consists of an annular ring member 24 and a fixing part 25 that connects the ring member 24 to the fixing ring 2. The sensor substrate 22 has an electronic component such as a substrate 36 (described later) and a magnetic sensor element 37 attached to the substrate 36.

[0035] The ring member 24 has a substrate guide portion 26 into which the sensor substrate 22 is inserted in the axial direction, a protrusion 27 projecting from the other axial side (left side in Figure 1) of the closed wall of the substrate guide portion 26 toward one axial end (right side in Figure 1) at a position facing the magnetic sensor element 37 in the axial direction, a pair of protruding portions 28 included in the radial outer wall of the substrate guide portion 26 that support the substrate 36 from the radial outside, and an assembly portion 29 that overlaps the inner circumference of the outer ring width surface on one axial side of the fixed ring 2. The substrate guide portion 26 including the pair of protruding portions 28, the protrusion 27, and the protruding portions 28 are provided integrally without any joints.

[0036] The substrate guide portion 26 forms an open space toward one axial side (right side in Figure 1), and extends axially to guide the substrate 36 of the sensor substrate 22, which is inserted into this space from one axial side toward the other axial side (left side in Figure 1), in the axial direction. The substrate guide portion 26 is also provided on a portion of the circumferential direction of the ring member 24 and protrudes radially outward. The radial outer wall of the substrate guide portion 26 is cut out radially to match the shape of the connector 42 of the sensor substrate 22, which will be described later. Through holes 30 corresponding to the positions of the insert fittings 38, which will be described later, are formed on both sides of the cut-out portion of the radial outer wall of the substrate guide portion 26, and bolts 40 are inserted through them.

[0037] The protrusion 27 extends axially parallel to the pair of ridges 28 of the substrate guide portion 26. The end of the protrusion 27 on one axial side (right side in Figure 1) is a surface perpendicular to the axial direction (i.e., a surface along the radial direction). The axial dimensions of the end of the protrusion 27 on one axial side are controlled with respect to the outer ring width surface 7.

[0038] The protruding portion 28 extends axially from the closing wall on the other axial side (left side in Figure 1) of the substrate guide portion 26 to the end face on the axial side of the substrate guide portion 26. As shown in Figure 2, the pair of protruding portions 28 are formed separately on both sides (left and right sides in the figure) in the circumferential direction of the substrate guide portion 26. On the radially inward side of the protruding portion 28, a substrate support surface 31 is formed that supports the substrate 36 in a direction perpendicular to the surface of the substrate 36. The substrate support surface 31 supports the surface 41 of the substrate 36 from the radial direction. The substrate support surface 31 is a surface that is aligned perpendicular to a straight line in the radial direction and along the axial direction, and is in direct contact with the surface 41 of the substrate 36. The position of the substrate support surface 31 is set so that the gap between the magnetic ring 23 and the magnetic sensor element 37, which will be described later, is a specified value.

[0039] As shown in Figure 1, the assembly portion 29 extends around the entire inner circumference of the ring member 24 and fits into the groove shoulder of the circumferential groove 10 on one axial side (right side in Figure 1) of the fixed ring 2.

[0040] The entire ring member 24 is integrally molded from resin. The material of the ring member 24 can be a thermoplastic resin, such as polyphenylene sulfide (PPS) filled with glass fibers or calcium carbonate. Furthermore, when used in environments with generally little temperature fluctuation, such as room temperature, materials such as polybutylene terephthalate (PBT), polyacetal (POM), and polycarbonate (PC) can be used.

[0041] The fixing component 25 has an annular crimping fitting 32 and an annular rubber portion 33 provided on the outer circumference of the crimping fitting 32. As shown in Figures 1 and 3, the crimping fitting 32 consists of an annular portion 34 extending around the entire circumference and a plurality of claws 35 provided at multiple locations on the annular portion 34 in the circumferential direction and extending toward the ring member 24. The annular portion 34 has a substantially L-shaped cross-section with a plate portion extending along the radial direction and a plate portion extending along the axial direction. The annular portion 34 protrudes radially inward from the cylindrical surface 9 of the fixing ring 2 and faces radially toward the outer ring width surface 7 on one axial side (right side in Figure 1). The plurality of claws 35 are crimped to the inner circumferential surface of the ring member 24 and fixed to the ring member 24. In the state before crimping shown in Figure 4, the plurality of claws 35 are shaped to extend in the axial direction. As shown in Figure 1, the rubber portion 33 is formed to protrude radially outward from the crimping fitting 32. The rubber part 33 is fitted into the circumferential groove 10 on one axial side (right side in Figure 1) of the fixed wheel 2.

[0042] The crimping fitting 32 can be formed by press forming (including deep drawing) of a thin sheet (such as a mild steel sheet or stainless steel sheet). The rubber part 33 can be made of an oil-resistant rubber material (such as NBR, HNBR, FKM, or ACM). The fixing part 25 may be configured by vulcanizing and bonding the rubber part 33 to the crimping fitting 32.

[0043] The sensor substrate 22 is a circuit board that constitutes the electrical circuit of the rotation sensor 20. The substrate 36 is a printed wiring board, such as a glass epoxy substrate or a flexible substrate. The substrate 36 is formed in a rectangular shape when viewed radially. The substrate 36 is in the shape of a rectangular plate. The four rectangular sides of the substrate 36 are formed by edges created when the substrate 36 was divided by a substrate dividing machine. Two opposing edges of the substrate 36 are generally aligned with the axial direction, and another pair of opposing edges are generally aligned with a virtual plane perpendicular to the axial direction.

[0044] As shown in Fig. 2, an insert fitting 38 (through-hole tap) having an internal thread is fitted into the base plate 36. The insert fitting 38 is cylindrical, and a flange portion 39 extending outward is formed at one end of the cylinder. The insert fitting 38 is attached such that the flange portion 39 is located on the radially inner side (lower side in the figure) of the base plate 36. The insert fittings 38 are provided at two locations on both sides in the circumferential direction. The sensor substrate 22 is fixed by a bolt 40 inserted through the through hole 30 being screwed into the internal thread of the insert fitting 38. The sensor substrate 22 is positioned in the radial direction relative to the sensor housing 21 by the fastening bringing the plate surface 41 on the opposite side (upper side in the figure) from the surface mounting side of the base plate 36 into contact with the substrate receiving surface 31.

[0045] It is desirable that the base plate 36 is made of glass-filled epoxy resin. Furthermore, when a material having a compressive strength of 340 to 500 MPa and a bending strength of 390 to 550 MPa is selected, rigidity is increased, thereby improving rotation detection accuracy. In addition, by using a multilayer substrate, the substrate dimensions can be further reduced. In addition to the magnetic sensor element 37 and the insert fitting 38, various electronic components such as a non-volatile memory, a connector 42, and a protection circuit are surface-mounted on the base plate 36 in advance. The various electronic components are mounted for the purpose of attenuating or blocking harmful external electromagnetic noise and the like.

[0046] Examples of the various electronic components include common mode filters, single mode filters, resistors, ceramic capacitors, coils, varistors, inductors, ceramic filters, EMI filters, and ferrite beads. The magnetic sensor, ceramic capacitor, non-volatile memory, and the like are mounted on the surface side (lower side in Fig. 2) of the sensor substrate 22. On the other hand, a protection circuit, the connector 42, and the like are mounted on the opposite side surface.

[0047] As shown in FIG. 1, the magnetic sensor element 37 is an element that converts the magnetic field of a magnet 44, which will be described later, into an electric signal. The magnetic sensor element 37 is formed as an integrated circuit, and includes a body portion such as a resin mold that seals a built-in circuit such as a magnetically sensitive portion. The magnetic sensor element 37 is surface-mounted on a substrate 36. The magnetically sensitive portion of the magnetic sensor element 37 is arranged at a position radially opposed to the magnet 44. The magnetic sensor element 37 is, for example, a magnetic sensor utilizing the Hall effect, and incorporates a main track detection unit that detects the magnetic field of the main track of a magnetic ring 23 described later and a sub track detection unit that detects the magnetic field of the sub track of the magnetic ring 23 in the sensor body. The body portion of the magnetic sensor element 37 has a flat surface along a direction perpendicular to the mounting surface of the substrate 36. The posture of the magnetic sensor element 37 relative to the substrate 36 is set such that when the substrate 36 of the sensor substrate 22 is inserted into the substrate guide portion 26 along the axial direction, the aforementioned flat surface of the magnetic sensor element 37 is oriented along a plane perpendicular to the axial direction. The magnetic sensor element 37 is axially positioned relative to the sensor housing 21 by axially abutting against the convex portion 27 at the flat surface thereof.

[0048] The magnetic sensor element 37 may have a built-in or externally attached correction function that calculates changes in the magnetic field detected by the main track detection unit and the sub track detection unit during operation of the rolling bearing 1 to correct angular errors in the rotational direction, and a memory that stores correction contents and the like. The detection method can be set to an incremental method, an absolute method, or the like.

[0049] The sensor-side electric circuit necessary for the magnetic sensor element 37 to perform input and output with the outside is constructed on the substrate 36. The connector 42 is an input / output terminal of the sensor-side electric circuit, and is connected to an external electric circuit. The connector 42 incorporates required electrodes including an electrode for a signal line that transmits an output signal of the magnetic sensor to the outside, and an electrode for a power supply line that supplies electric power to the magnetic sensor from the outside. The connector 42 is shaped to allow a cable (not shown) to be inserted and removed in the radial direction.

[0050] The number of magnetic sensor elements arranged using the sensor housing may be one or more. When using multiple magnetic sensor elements, they may be mounted on a single substrate, or they may be mounted on two or more substrates, with corresponding substrate guides provided on the sensor housing for each. The sensor housing may also be used to arrange sensors other than rotation sensors, such as temperature sensors and vibration sensors. These temperature sensors, etc., may be mounted on the substrate, or on a separate substrate and then attached to the sensor housing.

[0051] The circuit board 36 and various electronic components may be covered with a sheet of thermosetting resin or coated with a resin-based moisture-proof film to prevent migration. It is preferable to use lead-free solder for fixing the various electronic components. The magnetic sensor element 37, ceramic capacitors (not shown), and non-volatile memory are surface-mounted on the same side of the sensor board 22, while other protective circuit components and connectors 42 are surface-mounted on the opposite side.

[0052] In particular, by mounting the ceramic capacitor (capacitor) in a position close to the power supply terminal and GND terminal of the magnetic sensor element, external electrical noise (voltage change) components superimposed on the power supply can be effectively grounded. Furthermore, the substrate 36, magnetic sensor element 37, and various electronic components may be covered with a sheet-like thermosetting resin or coated with a resin-based moisture-proof film to prevent migration.

[0053] The magnetic ring 23 consists of a cylindrical core metal 43 and a magnet 44 fixed to the core metal 43. The core metal 43 is fitted onto the outer surface of the stationary wheel 3. The core metal 43 is press-formed from a single, seamless metal plate. The core metal 43 is formed in a stepped cylindrical shape and has a small-diameter cylindrical portion 45 that fits onto the outer surface of the stationary wheel 3, and a large-diameter cylindrical portion 46 that is larger in diameter than the small-diameter cylindrical portion 45 and concentric with the small-diameter cylindrical portion 45.

[0054] The small-diameter cylindrical portion 45 is connected to the large-diameter cylindrical portion 46 via a flat portion 47 that extends radially inward from the axial end of the large-diameter cylindrical portion 46 (left side in the figure). The flat portion 47 is formed around the entire circumference. The large-diameter cylindrical portion 46 is positioned axially outward from the stationary wheel 3. The magnetic ring 23 is positioned so as not to come into contact with the sensor housing 21 or the fixing parts 25. Note that the small-diameter cylindrical portion 45 and the large-diameter cylindrical portion 46 do not need to be continuous around the entire circumference; it is also possible to provide outer flanges intermittently in the circumferential direction and create slits (spaces) between adjacent outer flanges in the circumferential direction.

[0055] Examples of metal plates used for the core metal 43 include mild steel plates and stainless steel plates. Examples of mild steel plates include SPCC, SPCT, SPCD, SPCE, and SPCEN as specified in the Japanese Industrial Standards (JIS). Examples of stainless steel plates include SUS430, SUS201, SUS304, SUS316, SUS321, SUS403, and SUS410 as specified in the Japanese Industrial Standards (JIS). Furthermore, when machining the core metal 43, it is also possible to use carbon steel for machine structures such as S45C as specified in the Japanese Industrial Standards (JIS). In addition, using a magnetic material for the core metal 43 is advantageous in improving magnetic properties.

[0056] The magnet 44 is formed in a cylindrical shape from a rubber magnet material. The magnet 44 is bonded to the outer surface of the large-diameter cylindrical portion 46 of the core metal 43. The magnet 44 has an inner circumference and outer circumference that are concentric with the core metal 43 and is shaped along the radial direction. The outer diameter of the magnet 44 is set to a dimension that does not interfere with the magnetic sensor element 37.

[0057] The rubber magnet material is made by mixing magnetic powder with rubber. Examples of rubber include NBR, HNBR, FKM, and ACM. Examples of magnetic powder include ferrite powder, neodymium (Nd) powder, and samarium (Sm) powder. The magnet 44 may be bonded to the core metal 43 along with vulcanization. When performing this vulcanization bonding, it is advisable to apply adhesive to the bonding surface of the core metal 43 in advance.

[0058] The magnet 44 is multi-pole magnetized so that it alternately has north poles and south poles in the circumferential direction. In other words, the magnet 44 is magnetized so that it alternately has opposite poles in the circumferential direction. The magnets 44 are arranged in two rows (two rows in this embodiment) in the axial direction. The number of magnetized pole pairs is not limited, but the number of pole pairs of the magnets 44 forming the sub-track (second track) is n-1 for the number of pole pairs of the magnets 44 forming the main track (first track). Also, the number of magnetized rows (tracks) that are multi-pole magnetized is not limited. Furthermore, for example, if the magnetized rows of the magnetic ring 23 are two rows, it is desirable to magnetize them so that the axial boundary between the main track and the sub-track is at the axial center between the magnetizing part of the main track detection part and the magnetizing part of the sub-track detection part in the magnetic sensor element 37. The magnetization positions of the main track and the sub-track may be such that the main track is located on one axial side or on the other axial side.

[0059] The magnetization process for the magnet 44 is not shown in the diagram, but for example, a magnetized ring is formed by fixing the magnet 44 to the outer circumferential surface of the large-diameter cylindrical portion 46 of the core metal 43. This magnetized ring is mounted on the rotating chuck (including the mounting jig) of the magnetization device and rotated circumferentially at a constant rotational speed, thereby magnetizing the ring to multiple poles, alternating between north and south poles in the circumferential direction. The magnetization device has a magnetization coil wound around a magnetization yoke and is positioned on the outer circumferential surface or width surface (flat surface) of the magnetized ring with a desired gap. Furthermore, the ring is magnetized to multiple poles by alternately switching the direction of the current flowing through the magnetization coil in synchronization with the rotation of the magnetized ring. The number of magnetized poles can be determined as appropriate.

[0060] Another magnetization method involves using a magnetization device in which a magnetization coil is wound around a magnetization yoke having a convex shape corresponding to the number of magnetic poles, which is positioned with a desired gap on the outer circumferential or width surface (flat surface) of the ring to be magnetized, which is fixed in a non-rotating state. In this case, the direction of the current flowing through the magnetization coil can be limited to one direction, and magnetization can be completed in a short time. This magnetization method is suitable for magnetizing Nd-based, Sm-based, and other materials.

[0061] This document explains how to assemble this bearing with a rotation sensor.

[0062] (1. Method of mounting the sensor substrate 22) As shown in Figure 1, the sensor substrate 22 is inserted into the substrate guide portion 26 and brought into axial contact with the protrusion portion 27. Next, as shown in Figure 2, the back surface 41 of the substrate 36 is brought into contact with the substrate receiving surfaces 31 of the pair of protrusions 28. Next, the bolts 40 are inserted into the through holes 30 and screwed into the insert fittings 38 that are pre-mounted on the substrate 36, thereby fixing the substrate 36 in place by pressing it against the pair of substrate receiving surfaces 31.

[0063] (2. Method of attaching the fixing part 25) As shown in Figure 4, the receiving jig 50 is inserted into the inner circumferential surface of the stationary wheel 3 from the other axial side (lower side in the figure), and the receiving jig 50 is pressed against the outer ring width surface 7 on the other axial side (lower side in the figure). The receiving jig 50 is supported from the other axial side. Next, with the rubber part 33 of the fixing part 25 positioned against the entrance of the circumferential groove 10 of the stationary wheel 2, the press-fitting jig 51 is inserted into the inner circumferential surface of the stationary wheel 3 and brought into contact with the annular part 34 of the crimping fitting 32. Next, a load is applied to the press-fitting jig 51 toward the other axial side (lower side in the figure) to push it in, thereby securely fitting the rubber part 33 into the circumferential groove 10. The position where the receiving jig 50 and the press-fitting jig 51 are in contact in the axial direction is the stroke end in the pushing direction. Furthermore, the stroke end of the press-fitting jig 51 may be designed such that it does not come into contact with the receiving jig 50 even when the press-fitting jig 51 is fully pushed in, and the load may be controlled by the repulsive force of the rubber part 33 fitted into the circumferential groove 10.

[0064] (3. Method of attaching the assembly portion 29 of the sensor housing 21) As shown in Figure 5, the receiving jig 50 is inserted into the inner circumferential surface of the stationary wheel 3 from the other axial side (lower side in the figure) of the stationary wheel 3, and the receiving jig 50 is pressed against the outer ring width surface 7 on the other axial side (lower side in the figure). The receiving jig 50 is supported from the other axial side. Next, the assembly portion 29 of the sensor housing 21 is fitted between the groove shoulder of the circumferential groove 10 of the fixed wheel 2 and the outer circumferential surface of the crimping fitting 32.

[0065] (4. Method of fixing the assembly 29 of the sensor housing 21) The following three methods of fixing the assembly 29 of the sensor housing 21 will be explained: "4-1. Method 1 of fixing the assembly 29 of the sensor housing 21", "4-2. Method 2 of fixing the assembly 29 of the sensor housing 21", and "4-3. Method 3 of fixing the assembly 29 of the sensor housing 21".

[0066] (4-1. Method for fixing the assembly portion 29 of the sensor housing 21) As shown in Figure 6, the receiving jig 50 is pressed against the outer ring width surface 7 on the other axial side (lower side in the figure), and the centering jig 52 is inserted into the inner circumferential surface of the receiving jig 50 and the inner circumferential surface of the stationary ring 3. The receiving jig 50 and the centering jig 52 are supported from the other axial side. Next, the crimping jig 53 is inserted from one axial side (upper side in the figure) and fitted into the outer circumferential surface of the centering jig 52, and the claw crimping portion 54 provided on the crimping jig 53 is aligned with the multiple claws 35 of the fixing part 25 (circumferential alignment). Next, a wave washer 56 is inserted into the recess 55 provided on the upper part of the crimping jig 53, and the pressing jig 57 is placed on top of it.

[0067] Next, a load is applied to the pressing jig 57 in the other axial direction (downward in the figure) to flex the wave washer 56, and the crimping jig 53 is pushed in the other axial direction (downward in the figure) via the wave washer 56. As a result, the claw crimping section 54 bends multiple claws 35, fixing the assembly section 29 to the fixed wheel 2. The stroke end in the pushing direction of the crimping jig 53 is controlled by the amount of flex of the wave washer 56 or the pushing load.

[0068] (4-2. Method for fixing the assembly portion 29 of the sensor housing 21 2) As shown in Figure 7, the receiving jig 50 is inserted into the inner circumferential surface of the stationary wheel 3 from the other axial side (lower side in the figure) of the stationary wheel 3, and the receiving jig 50 is pressed against the outer ring width surface 7 on the other axial side (lower side in the figure). The receiving jig 50 is supported from the other axial side. Next, the crimping jig 53 is inserted from one axial side (upper side in the figure), and the claw crimping portion 54 provided on the crimping jig 53 is aligned with the multiple claws 35 of the fixing part 25 (circumferential alignment).

[0069] Next, by applying a load to the crimping jig 53 in the other axial direction (downward in the figure), the multiple claws 35 are bent at the claw crimping section 54, and the assembly section 29 is fixed to the fixing wheel 2. The position where the receiving jig 50 and the crimping jig 53 come into contact is defined as the stroke end in the pushing direction of the crimping jig 53.

[0070] (4-3. Method 3 for fixing the assembly portion 29 of the sensor housing 21) As shown in Figure 8, the receiving jig 50 is pressed against the outer ring width surface 7 on the other axial side (lower side in the figure), and the centering jig 52 is inserted between the inner circumferential surface of the receiving jig 50 and the inner circumferential surface of the stationary ring 3. The receiving jig 50 and the centering jig 52 are supported from the other axial side. Next, the crimping jig 53 is inserted from one axial side (upper side in the figure), and the claw crimping portion 54 provided on the crimping jig 53 is aligned with the multiple claws 35 of the fixing part 25 (circumferential alignment).

[0071] Next, by applying a load to the crimping jig 53 in the other axial direction (downward in the figure), the multiple claws 35 are bent at the claw crimping section 54, and the assembly section 29 is fixed to the fixed wheel 2. The position where the centering jig 52 and the crimping jig 53 come into contact is the stroke end in the pushing direction of the crimping jig 53.

[0072] (5. Method of fixing the magnetic ring 23) Two methods of fixing the magnetic ring 23 will be explained below: "5-1. Method of fixing the magnetic ring 23 1" and "5-2. Method of fixing the magnetic ring 23 2".

[0073] (5-1. Method for fixing the magnetic ring 23 1) As shown in Figure 9, the support jig 50 is inserted into the inner circumferential surface of the stationary ring 3 from the other axial side (lower side in the figure), and the support jig 50 is pressed against the inner ring width surface 11 on the other axial side (lower side in the figure). The support jig 50 is supported from the other axial side. Next, the tip of the small diameter cylindrical portion 45 of the mandrel 43 on the other axial side (lower side in the figure) is placed near the end of the outer circumferential surface of the stationary ring 3 on one axial side (upper side in the figure). Next, the pressing jig 57 is inserted into the inner circumferential surface of the stationary ring 3, and also into the inner circumferential surface of the small diameter cylindrical portion 45 of the mandrel 43, thereby centering the mandrel 43 with respect to the inner circumferential surface of the stationary ring 3. Next, with the stepped portion 58 provided on the pressing jig 57 in contact with the flat portion 47 of the core metal 43, a load is applied to the pressing jig 57 in the other axial direction to press the core metal 43 into the outer circumferential surface of the stationary wheel 3.

[0074] Furthermore, a pressing jig 57 is used in which the dimensions of the stepped portion 58 are controlled so that the axial length dimension between the flat portion 47 of the mandrel 43 and the inner ring width surface 11 on one axial side (upper side in the figure) is a specified dimension. In addition, the position where the pressing jig 57 and the inner ring width surface 11 on one axial side come into contact is defined as the stroke end of the pressing jig 57 in the pushing direction. In this way, the magnetic ring 23 can be accurately positioned in the axial direction relative to the inner ring width surface 11.

[0075] (5-2. Method for fixing the magnetic ring 23 2) As shown in Figure 10, the support jig 50 is pressed against the inner ring width surface 11 on the other axial side (lower side in the figure), and the centering jig 52 is inserted between the inner circumferential surface of the support jig 50 and the inner circumferential surface of the stationary wheel 3. The support jig 50 and the centering jig 52 are supported from the other axial side. Next, the guide jig 59 is attached to the outer circumferential surface of the stationary wheel 2, and the magnetic ring 23 is inserted into the inner circumferential surface of the guide jig 59 with a small radial gap. Also, the pushing jig 57 is attached to the outer circumferential surface of the centering jig 52 and inserted into the inner circumferential surface of the mandrel 43, thereby centering the mandrel 43 with respect to the inner circumferential surface of the stationary wheel 3. Next, with the stepped portion 58 provided on the pushing jig 57 in contact with the flat portion 47 of the mandrel 43, a load is applied to the pushing jig 57 in the other axial direction to press the mandrel 43 into the outer circumferential surface of the stationary wheel 3.

[0076] A press jig 57 with a stepped portion 58 whose dimensions are controlled is used so that the axial length dimension between the flat portion 47 of the mandrel 43 and the inner ring width surface 11 on one axial side is a specified dimension. Furthermore, the position where the press jig 57 and the inner ring width surface 11 on one axial side come into contact is defined as the stroke end of the press jig 57 in the pushing direction. In this way, the magnetic ring 23 can be accurately positioned in the axial direction relative to the inner ring width surface 11. It is desirable to minimize the radial gap between each jig as much as possible and to reduce the coefficient of friction by applying lubricants or release agents to their surfaces.

[0077] In this embodiment of the bearing with a rotary sensor (see Figures 1 and 2), as described above, a substrate guide portion 26 inserted axially into the sensor housing 21 and a protrusion 27 projecting from the sensor substrate 22 at a position axially opposite to the magnetic sensor element 37 are integrally provided without any joints. Since the magnetic sensor element 37 is positioned axially relative to the sensor housing 21 by axial contact with the protrusion 27, the axial positioning of the magnetic sensor element 37 relative to the sensor housing 21 can be made with high precision without being affected by errors in the cut shape of the end of the substrate 36 or errors in the mounting position of the magnetic sensor element 37 on the substrate 36.

[0078] Furthermore, this bearing with a rotation sensor includes a substrate guide portion 26 that supports the plate surface 41 of the substrate 36, and the sensor substrate 22 is positioned radially relative to the sensor housing 21 by fastening it so that the plate surface 41 and the substrate support portion 31 are in contact, thus enabling accurate radial positioning relative to the sensor housing 21.

[0079] Furthermore, in this bearing with a rotation sensor, an insert fitting 38 with an internal thread is fitted into the substrate 36, and a through hole 30 corresponding to the position of the insert fitting 38 is formed in the sensor housing 21. The sensor housing 21 has a bolt 40 that passes through the through hole 30 and is screwed into the insert fitting 38, and the plate surface 41 and the substrate receiving surface 31 come into contact by the screwing of the bolt 40 and the insert fitting 38, and the sensor substrate 22 is fixed to the sensor housing 21. As a result, the plate surface 41 of the substrate 36 is fastened to the substrate receiving surface 31 by the screwing of the insert fitting 38 fitted into the substrate 36 and the bolt 40 that passes through the through hole 30 of the sensor housing 21, and the axial position of the substrate 36 with respect to the substrate guide portion 26 is also fixed, so the sensor substrate 22 can be reliably fixed in the appropriate position relative to the sensor housing 21.

[0080] Furthermore, in this bearing with a rotation sensor, a circumferential groove 10 extending around the entire circumference is formed in the fixed ring 2, the sensor housing 21 has a ring member 24 including a substrate guide portion 26 and a protrusion portion 27, and a fixing part 25 that connects the ring member 24 to the fixed ring 2, the fixing part 25 has a crimping fitting 32 including a plurality of claws 35 provided at multiple locations in the circumferential direction and extending toward the ring member 24, and an annular rubber portion 33 provided on the outer circumference of the crimping fitting 32, the ring member 24 is fixed to the crimping fitting 32 by crimping the plurality of claws 35 toward the ring member 24, and the crimping fitting 32 is fixed to the fixed ring 2 by fitting the rubber portion 33 into the circumferential groove 10 of the fixed ring 2, so that the rubber portion 33 of the fixing part 25 into the circumferential groove 10 of the fixed ring 2 and the crimping of the fixing part 25 toward the ring member 24 are easy, and no machining is required to carry out these.

[0081] Furthermore, this bearing with a rotation sensor has an annular magnet 44 on a magnetic ring 23 that is magnetized so that the polarities alternate in the circumferential direction. Since the magnets 44 are arranged in double rows in the axial direction on the magnetic ring 23, the rotation angle, rotation speed, rotation direction, etc. can be detected with high precision by the sensor substrate 22 based on the changes in the magnetic fields of each of the double-row magnets 44.

[0082] In the embodiment shown in Figure 1, the outer ring was a fixed ring 2 and the inner ring was a rotating ring 3, but as shown in Figure 11, the outer ring can be a rotating ring 3 and the inner ring can be a fixed ring 2. In this case, the sensor housing 21 is attached to the circumferential groove 10 formed on the outer circumference of the fixed ring 2, and the magnetic ring 23 is attached to the rotating ring 3.

[0083] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended.

[0084] 1 Rolling bearing 2 Fixed ring 3 Rotating ring 4 Rolling element 10 Circumferential groove 20 Rotation sensor 21 Sensor housing 22 Sensor substrate 23 Magnetic ring 24 Ring member 25 Fixing part 26 Substrate guide part 27 Protrusion 30 Through hole 31 Substrate receiving surface 32 Crimping fitting 33 Rubber part 35 Claw 36 Substrate 37 Magnetic sensor element 38 Insert fitting 40 Bolt 41 Plate surface 44 Magnet

Claims

1. A rolling bearing (1) having a fixed ring (2), a rotating ring (3), and a plurality of rolling elements (4), and a rotation sensor (20) for detecting the relative rotational motion of the rotating ring (3) with respect to the fixed ring (2), wherein the rotation sensor (20) has a sensor housing (21) attached to the fixed ring (2), a sensor substrate (22) attached to the sensor housing (21), and a magnetic ring (23) attached to the rotating ring (3), wherein the sensor substrate (22) has a substrate (36) and a magnetic sensor element (37) attached to the substrate (36), and the magnetic sensor element (37) is radially opposed to the magnetic ring (23) in the bearing with the rotation sensor, wherein the magnetic sensor element (37) is surface-mounted on the substrate (36), The bearing with a rotary sensor is characterized in that the sensor housing (21) has a substrate guide portion (26) into which the substrate (36) is inserted in the axial direction, and a protrusion (27) that protrudes at a position facing the magnetic sensor element (37) in the axial direction, and the magnetic sensor element (37) is positioned in the axial direction relative to the sensor housing (21) by axial contact with the protrusion (27).

2. The bearing with a rotary sensor according to claim 1, wherein the substrate guide portion (26) includes a substrate receiving surface (31) that supports the plate surface (41) of the substrate (36), and the sensor substrate (22) is positioned radially relative to the sensor housing (21) by being fastened so that the plate surface (41) and the substrate receiving surface (31) are in contact with each other.

3. The bearing with a rotary sensor according to claim 2, wherein an insert fitting (38) having an internal thread is fitted into the substrate (36), a through hole (30) corresponding to the position of the insert fitting (38) is formed in the sensor housing (21), the sensor housing (21) has a bolt (40) that is threaded through the through hole (30) and screwed into the insert fitting (38), and the plate surface (41) and the substrate receiving surface (31) come into contact by the threading of the bolt (40) and the insert fitting (38), and the sensor substrate (22) is fixed to the sensor housing (21).

4. The fixed ring (2) has a circumferential groove (10) extending around its entire circumference, the sensor housing (21) has a ring member (24) including the substrate guide portion (26) and the protrusion (27), and a fixing part (25) that connects the ring member (24) to the fixed ring (2), the fixing part (25) has a crimping fitting (32) including a plurality of claws (35) provided at multiple locations in the circumferential direction and extending toward the ring member (24), and an annular rubber portion (33) provided on the crimping fitting (32), the ring member (24) is fixed to the crimping fitting (32) by crimping the plurality of claws (35) toward the ring member (24), The bearing with a rotation sensor according to claim 1 or 2, wherein the crimping fitting (32) is fixed to the fixed ring (2) by fitting the rubber portion (33) into the circumferential groove (10) of the fixed ring (2).

5. The bearing with a rotation sensor according to claim 1 or 2, wherein the magnetic ring (23) has annular magnets (44) that are magnetized alternately in opposite polarities in the circumferential direction, and the magnets (44) are provided in double rows in the axial direction on the magnetic ring (23).

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