Bearing with rotation sensor

Abstract

A bearing with a rotation sensor, in which a magnet of a magnet ring and a magnetic sensor face each other in the axial direction at a position on one axial side with respect to a rolling bearing, and the magnet is positioned on the one axial side with respect to the magnetic sensor, is further miniaturized in the axial direction. An outer ring (4), which is a raceway ring of one of an inner ring (3) and an outer ring (4) of a rolling bearing (1), has: a width surface (9a) positioned at one axial end of both ends defining the width of the outer ring (4); and a cutout section (18) that is recessed from the width surface (9a) toward the other axial side. The magnetic sensor (15) is attached to the cutout portion (18).

Description

Technical Field

[0001] The present invention relates to a bearing with a rotation sensor, comprising a rolling bearing and a magnetic rotation sensor for detecting relative rotational motion between an inner ring and an outer ring of the rolling bearing. Background Art

[0002] Achieving miniaturization and lightweighting in industrial robots and other machinery offers various advantages. For example, miniaturization of industrial robots reduces the size of their installation space. Furthermore, lightweighting industrial robots can reduce the inertial forces acting on driven parts, such as arms, that move around joints. This can suppress the shaking and vibration of the driven parts after they stop, reducing the time required for them to decay. This also reduces the power consumption of each action, contributing to energy savings.

[0003] To reduce the size and weight of machinery such as industrial robots, their components also need to be miniaturized. In addition to miniaturization of individual components, the integration of these components is becoming increasingly effective. As one such approach, a bearing with a rotation sensor is designed to integrate a magnetic rotation sensor installed in a rotating part with a rolling bearing supporting the rotating part to control the movement of these machines. This reduces the space required to mount these components and the time required for assembly.

[0004] This bearing with a rotation sensor includes: a rolling bearing having an inner ring, an outer ring, and multiple rolling elements; and a magnetic rotation sensor that detects the relative rotational motion between the inner and outer rings. The magnetic rotation sensor comprises a magnetic sensor and a magnetic ring. The magnetic sensor is attached to the raceway of one of the inner and outer rings. The magnetic ring is attached to the other raceway, opposite the other raceway. When the bearing with a rotation sensor is assembled into a machine, one raceway serves as a stationary ring that does not rotate. The other raceway serves as a rotating ring that rotates integrally with the machine's rotating components. The magnetic ring has a magnet that is magnetized with alternating polarity (north and south) in the circumferential direction. The magnetic sensor converts the changes in the magnetic field caused by the integral rotation of the other raceway and the magnetic ring into an electrical output signal and transmits the generated output signal.

[0005] The configuration of the magnets and magnetic sensors in a magnetic ring can be broadly categorized into two types: radially opposed and axially opposed. The radially opposed configuration forms the magnets on surfaces extending axially, making it suitable for radially miniaturizing the bearing with a rotation sensor. The axially opposed configuration forms the magnets on surfaces extending radially, making it suitable for axially miniaturizing the bearing with a rotation sensor. Patent Document 1 discloses a bearing with a rotation sensor that employs this axially opposed configuration.

[0006] The bearing with a rotation sensor disclosed in Patent Document 1 is a wheel bearing device in which the inner ring of the rolling bearing serves as the rotating ring and the outer ring serves as the stationary ring. This rolling bearing is a multiple-row angular contact ball bearing with two rows of balls assembled between a single outer ring (stationary ring) and two pairs of inner rings (rotating rings). The outer ring has no mating surface with the vehicle body; instead, its outer peripheral flange is secured to the vehicle body by bolts fastened axially. The magnetic ring consists of a metal core and a magnet fixed to the metal core. The metal core is embedded in a shoulder on one axial side of the inner ring to secure the magnetic ring to the inner ring. The magnetic sensor is mounted to the outer ring using a bracket. The bracket consists of an inner housing and an outer housing. The outer housing is embedded in the outer circumference of the inner housing holding the magnetic sensor and the outer circumference of the outer ring, with the outer ring end abutting against one axial width surface of the outer ring to secure it to the outer ring. The magnet is located axially to the side of the magnetic sensor, with the magnetic sensor positioned closer to the outer ring than the magnet. When the magnetic sensor and the magnet are arranged in this manner, there is no need for a mounting structure for arranging the magnetic sensor on one side of the magnetic ring in the axial direction. This is suitable for reducing the size of the bearing with a rotation sensor in the axial direction.

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-101352

[0008] However, the structure of the bearing with a rotation sensor disclosed in Patent Document 1 has limitations in further miniaturizing the bearing with a rotation sensor in the axial direction. Specifically, if the inner housing is thinned in the axial direction, the magnetic sensor can be shifted toward the other axial side, shortening the axial distance between the width surface of the outer ring and the magnetic sensor. The magnetic ring is also positioned closer to the other axial side by this shortened amount, further miniaturizing the bearing with a rotation sensor in the axial direction. However, if the inner housing is excessively thinned in the axial direction, the fitting width between the outer housing and the inner housing is insufficient, making it impossible to fully support the inner housing in the radial direction. There is a concern that the positional offset of the magnetic sensor relative to the magnet may adversely affect detection accuracy. Therefore, there are limitations in further miniaturizing the bearing with a rotation sensor in the axial direction by thinning the inner housing in the axial direction. Summary of the Invention

[0009] Therefore, the problem to be solved by the present invention is to further miniaturize the bearing with a rotation sensor in the axial direction, in which the magnet of the magnetic ring and the magnetic sensor are axially opposed to each other and the magnet is located on one axial side relative to the magnetic sensor.

[0010] In order to solve the above-mentioned problems, the present invention adopts structure 1, namely: a bearing with a rotation sensor, comprising: a rolling bearing having an inner ring, an outer ring and a plurality of rolling elements; and a magnetic rotation sensor for detecting the relative rotational movement of the inner ring and the outer ring, the magnetic rotation sensor comprising: a magnetic sensor mounted on a raceway ring of one of the inner ring and the outer ring; and a magnetic ring mounted on a raceway ring of the other of the inner ring and the outer ring, the magnetic ring comprising a magnet alternately magnetized to different poles in the circumferential direction, the magnet being axially opposed to the magnetic sensor at a position on one axial side relative to the magnetic sensor, the bearing with the rotation sensor being characterized in that the raceway ring on one side comprises: a width surface located at an end on one axial side of two ends defining the width of the raceway ring on the one side; and a notch recessed from the width surface on the other axial side, the magnetic sensor being mounted on the notch.

[0011] According to the above-described structure 1, one of the raceways has a notch recessed from a width surface located at an end portion on one axial side of the raceway width toward the other axial side. Therefore, the axial depth of the notch relative to the width surface allows the magnetic sensor to be positioned closer to the other axial side (the center of the width of the bearing with a rotation sensor), and the magnetic ring can also be positioned closer to the other axial side by that amount. Therefore, by attaching the magnetic sensor to the notch, the axial position of the magnetic sensor and the magnetic ring is set further toward the other axial side, compared to the structure of Patent Document 1, which requires the magnetic sensor to be positioned axially away from the width surface. This further reduces the size of the bearing with a rotation sensor in the axial direction.

[0012] A second structure, based on the first structure, can be employed, in which the magnetic sensor is mounted on the one raceway by bonding, screwing, or fitting. This structure allows the magnetic sensor to be mounted on the one raceway reliably and efficiently.

[0013] In addition to the above-mentioned configuration 1 or 2, a configuration 3 can be adopted, in which the magnetic sensor includes a ground electrode connected to the one raceway. According to this configuration 3, the one raceway can be effectively used as a body ground.

[0014] Configuration 4, based on any of Configurations 1 to 3 above, can be employed, in which the magnetic ring includes a metal core formed into an annular shape from a magnetic material, the metal core having a cover portion disposed on one axial side relative to the width surface of the one raceway ring, and the magnets are fixed to the other axial side of the cover portion. This configuration 4 blocks magnetic fields flowing from the metal core of the magnetic ring (external leakage magnetic fields), thereby protecting the magnetic field generated by the magnets of the magnetic ring (preventing magnetic field disturbance).

[0015] Configuration 5, based on any of Configurations 1 to 4, can be employed, wherein one of the raceways is formed by the outer ring, and the outer diameter of the magnetic ring is smaller than that of the outer ring. This configuration facilitates insertion of the bearing with a rotation sensor into a mechanical housing.

[0016] A sixth configuration, based on any of the aforementioned configurations 1 to 5, can be employed, wherein the first raceway ring includes a first circumferential surface extending between the two ends, including a contact portion with the rolling element; and a second circumferential surface extending between the two ends on the radially opposite side of the first circumferential surface, wherein the cutout portion is formed only in a portion axially to one side of the intersection of the line of action of the load at the contact portion and the second circumferential surface. This configuration eliminates the presence of a cutout portion on the line of action of the load at the contact portion between the first raceway ring and the rolling element, thereby preventing a reduction in the rigidity of the first raceway ring relative to the load.

[0017] Configuration 7, based on any of Configurations 1 to 6, can be employed, in which the entire portion of the magnetic sensor axially opposed to the magnetic ring is positioned axially on the other side of the width plane of the one raceway ring. This configuration 7 allows the magnetic ring to be positioned as close as possible to the width plane of the one raceway ring without being obstructed by the magnetic sensor, thereby significantly reducing the axial size of the bearing with a rotation sensor.

[0018] As described above, the present invention adopts the above-mentioned structure 1, so that the magnet of the magnetic ring and the magnetic sensor are axially opposed to each other on one axial side relative to the rolling bearing, and the bearing with a rotation sensor in which the magnet is located on one axial side relative to the magnetic sensor can be further miniaturized in the axial direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a longitudinal sectional front view showing a bearing assembly with a rotation sensor according to a first embodiment of the present invention.

[0020] Figure 2 Yes Figure 1 Cross-sectional view of the installation method of the magnetic ring.

[0021] Figure 3 It means Figure 1 A partial right side view of the magnetic sensor mounted in the cutout of the outer ring.

[0022] Figure 4 yes Figure 3 A cross-sectional view taken along line IV-IV.

[0023] Figure 5 Yes means installation Figure 3 A partial right side view of the cutout portion of the outer ring before the magnetic sensor.

[0024] Figure 6 yes Figure 5 A cross-sectional view taken along line VI-VI.

[0025] Figure 7 is with Figure 3 Similarly, a partial right side view of a mounting structure of a magnetic sensor according to a second embodiment of the present invention is shown.

[0026] Figure 8 yes Figure 7 A cross-sectional view taken along line VIII-VIII.

[0027] Figure 9 It is a longitudinal sectional front view showing a bearing assembly with a rotation sensor according to a third embodiment of the present invention. DETAILED DESCRIPTION

[0028] Based on the attached drawings Figures 1 to 6 A bearing with a rotation sensor according to a first embodiment will be described as an example of the present invention.

[0029] Figure 1 The illustrated bearing with a rotation sensor (hereinafter referred to as the bearing with a rotation sensor) includes a rolling bearing 1 and a magnetic rotation sensor 2. The bearing with a rotation sensor is used, for example, to detect the rotation angle or rotation speed of rotating electrical equipment.

[0030] The rolling bearing 1 includes an inner ring 3 , an outer ring 4 , a plurality of rolling elements 5 , a cage 6 for retaining the rolling elements 5 , and a seal 7 attached to the outer ring 4 .

[0031] Hereinafter, the direction along the central axis of rotation of the rolling bearing 1 (not shown) is referred to as the "axial direction", the radial direction is the direction perpendicular to the central axis of rotation is referred to as the "radial direction", and the circumferential direction of a circle around the central axis of rotation is referred to as the "circumferential direction". Figure 1 In the figure, the axial direction corresponds to the left-right direction, the radial direction corresponds to the up-down direction, and the center axes of the inner ring 3 and the outer ring 4 coincide with the rotation center axis of the rolling bearing 1.

[0032] The inner ring 3 and outer ring 4 are each composed of a single seamless raceway ring and are made of metal such as bearing steel.

[0033] The inner ring 3 and the outer ring 4 have width surfaces 8a and 9a, respectively, located at one of the two ends defining the width of the raceway rings 3 and 4 in the axial direction (at the Figure 1 width surface 8b, 9b, located in the other axial direction (in Figure 1the first circumferential surface 10, 11 including the contact portion with the rolling element 5 and extending between the ends of the raceway rings 3, 4; and the second circumferential surface 12, 13 extending between the ends of the raceway rings 3, 4 on the side opposite to the first circumferential surface 10, 11 in the radial direction.

[0034] Here, the width of the raceways 3 and 4 refers to the full axial length of the raceways. The width of the inner ring 3 and the width of the outer ring 4 are set to the same size, matching the width of the rolling bearing 1. Each width surface 8a, 8b, 9a, and 9b is an annular surface extending along the radial direction.

[0035] The first circumferential surfaces 10 and 11 include raceway surfaces 10a and 11a, respectively, that come into rolling contact with the rolling elements 5. The rolling elements 5 are interposed between the raceway surface 10a of the inner ring 3 and the raceway surface 11a of the outer ring 4. The cage 6 maintains the circumferential spacing between the rolling elements 5. As the inner ring 3 and outer ring 4 rotate relative to each other, the rolling elements 5 roll on the raceway surfaces 10a and 11a as the inner ring 3 rotates.

[0036] Although a corrugated retainer is exemplified as the retainer 6 , the material, structure, and manufacturing method of the retainer 6 are not particularly limited.

[0037] The second circumferential surface 12 of the inner ring 3 includes a fitting surface that defines the inner diameter of the rolling bearing 1. The inner ring 3 fits with a mechanical rotating shaft 100 at the fitting surface of its second circumferential surface 12. Therefore, the inner ring 3 functions as a rotating ring.

[0038] The second circumferential surface 13 of the outer ring 4 includes a fitting surface that defines the outer diameter of the rolling bearing 1. The outer ring 4 fits into the mechanical housing 101 at the fitting surface of its second circumferential surface 13. Therefore, the outer ring 4 serves as a stationary ring.

[0039] The housing 101 constitutes a body ground and is connected to the GND (ground) of a machine, such as a speed reducer drive unit used in a joint of a robot.

[0040] Furthermore, although a ball bearing is shown as an example of the rolling bearing 1, the rolling bearing may be replaced with a roller bearing. Furthermore, although a deep groove ball bearing is shown as an example of the ball bearing, the ball bearing may be replaced with an angular contact ball bearing.

[0041] The magnetic rotation sensor 2 detects the relative rotational motion between the inner ring 3 and the outer ring 4. The magnetic rotation sensor 2 includes a magnetic sensor 15 attached to the outer ring 4, which serves as one of the raceways of the inner ring 3 and the outer ring 4, and a magnetic ring 16 attached to the inner ring 3, which serves as the other of the raceways of the inner ring 3 and the outer ring 4.

[0042] The magnetic ring 16 is composed of an annular component having magnets 17 that are magnetized with alternating polarities in the circumferential direction. The magnetic sensor 15 comprises a circuit that converts the changes in the magnetic field accompanying the circumferential rotation of the magnet 17 into a predetermined output signal, which is then transmitted externally via an output electrode. This output signal is an electrical signal representing a physical quantity corresponding to the circumferential rotational motion of the magnet 17, and examples thereof include an absolute rotation angle signal and a rotation speed signal.

[0043] The outer ring 4 has a Figure 1 The width surface 9a of the side is axially directed to the other side (in the right direction) Figure 1 The magnetic sensor 15 is mounted on the cutout portion 18.

[0044] The magnet 17 of the magnetic ring 16 is axially located on one side (in Figure 1 The position on the (right) side is opposite to the magnetic sensor 15 in the axial direction.

[0045] The magnetic ring 16 is composed of a metal core 19 formed in a ring shape and a magnet 17 fixed to the metal core 19 .

[0046] The metal core 19 is composed of a cylindrical portion 19a which is pressed into the first circumferential surface 10 of the inner ring 3 and a cylindrical portion 19a which extends from one axial side (in the direction of the inner ring 3) of the cylindrical portion 19a. Figure 1 The cover plate portion 19b is configured to be bent in a radial direction on the side (right in the middle). The cover plate portion 19b is arranged on one side (in the middle) of the width surface of the raceway ring. Figure 1 On the other side of the axial direction of the cover plate portion 19b ( Figure 1 A magnet 17 is fixed to the plate surface on the side of the cover plate portion 19 (the left side). Figure 1 The end face on the right side is located on one of the two ends of the width of the bearing with a rotation sensor (in the axial direction). Figure 1 The end portion on the side (center is right).

[0047] The metal core 19 is formed by a metal plate formed by punching. A magnetic body is used as the metal plate. For example, a mild steel plate can be used as the magnetic body.

[0048] The magnet 17 is composed of a permanent magnet. As the magnet 17, a magnetic body such as a rubber magnet or a plastic magnet is generally used. Two magnetic codes, a main track and a secondary track, are magnetized in the axial direction at the same time in the magnet 17. The main track and the secondary track constituting the magnet 17 respectively have N poles and S poles alternating in the circumferential direction and are radially adjacent to each other, but the phase of the magnetic poles of the main track is different from the phase of the magnetic poles of the secondary track. When magnetizing the magnetic code, a space for grasping the metal core 19 is sometimes required, and a certain distance sufficient for the space can be ensured between the outer diameter surface of the barrel 19a and the magnet 17. As such a magnetic ring 16, for example, the magnetic ring disclosed in Japanese Patent Gazette No. 2018-124192 can be used. In addition, the number of columns of the magnetic track of the magnet 17 is not limited to two columns, and a magnetic code can also be magnetized in a single column.

[0049] Examples of methods for attaching the magnetic ring 16 to the inner ring 3 include press-fitting the cylindrical portion 19a into the first circumferential surface 10 of the inner ring 3 or bonding it with an adhesive to secure it to the inner ring 3. Alternatively, the magnetic ring 16 can be attached directly to the inner ring 3 by press-fitting, bonding, or the like. If the diameters of the first circumferential surface 10 of the inner ring 3 and the magnetic ring 16 do not match, they can be attached indirectly via a diameter conversion component.

[0050] When the magnetic ring 16 is pressed into the first circumferential surface 10 of the inner ring 3, it can be used Figure 2 The press-fitting jig Z shown in FIG. Make the other axial direction of the cylindrical portion 19a (in Figure 2 The end portion on the left side of the first peripheral surface 10 is connected to the axial side of the first peripheral surface 10 (in Figure 2 The end portion of the press-fitting jig Z is slightly fitted, and then the guide surface Z1 of the press-fitting jig Z is inserted into the inner diameter surface of the cylindrical portion 19a and pushed in until the press-fitting jig Z is aligned with one side of the axial direction of the inner ring 3 (in the middle). Figure 2 The press-fitting amount of the magnetic ring 16 into the inner ring 3 is determined by the axial length of the guide surface Z1 of the press-fitting jig Z. Therefore, in mass production of bearings with rotation sensors, by using a standard press-fitting jig Z to press-fit the magnetic ring 16 of each product into the inner ring 3, variations in the press-fitting amount of the magnetic ring 16 from product to product can be minimized.

[0051] The outer diameter Dm of the magnetic ring 16 is smaller than the outer diameter Do of the outer ring 4. Figure 1 As shown, when the rolling bearing 1 of the bearing with a rotation sensor is inserted into the inner side of the housing 101, the second circumferential surface 13 of the outer ring 4 can be grasped without being hindered by the outer periphery of the magnetic ring 16, or the outer diameter side end of the width surface 9a of the outer ring 4 can be pressed in the axial direction, thereby making it easy to insert the bearing with a rotation sensor into the mechanical housing 101.

[0052] like Figure 1、 Figure 3 、 Figure 4 As shown, the magnetic sensor 15 is composed of a circuit board 20 and a plurality of electronic components 21 and 22 mounted on the circuit board 20 .

[0053] Examples of the circuit board 20 include a glass epoxy board and a flexible board. The above-mentioned electronic components, such as the magnetic sensor element 21 and the connector 22, are soldered to the circuit board 20.

[0054] The magnetic sensor element 21 detects the two magnetic codes magnetized by the magnet 17. The magnetic sensor element 21 is arranged at a position facing the center of the two magnetic codes in the axial direction and separated from them by an appropriate air gap in the axial direction.

[0055] The connector 22 has built-in electrodes required for the signal line for transmitting the output signal of the magnetic sensor 15 to the outside, the electrode of the power line for supplying electric power to the magnetic sensor 15 from the outside, and the like. The connector 22 has a shape that is inserted into the counterpart connector in the axial direction and a shape that is inserted into the counterpart connector in the radial direction, depending on the direction in which the wires of the counterpart connector (not shown) connected thereto are taken out. Generally, after the bearing with a rotation sensor is installed on a machine, the counterpart connector is often inserted into the connector, so it is preferred to make the connector protrude in order to improve its insertability. However, in the case of using a connector with a shape that is inserted in the axial direction, the connector is made to protrude in the direction of the rotating shaft, and is therefore not suitable for miniaturizing the bearing with a rotation sensor in the axial direction. Therefore, in the bearing with a rotation sensor, the connector 22 having a shape that can be inserted into the counterpart connector in the radial direction is configured to protrude radially more than the rolling bearing 1, and is configured not to protrude more than one axial side (in the direction of the cover plate portion 19b). Figure 1 The end face of the side is axial (in the right) Figure 1 The side (center is right) is prominent.

[0056] In response to the relative rotation of the two raceways 3 and 4, the magnet 17 of the magnetic ring 16 rotates relative to the magnetic sensor element 21 of the magnetic sensor 15. As a result, the magnetic code (magnetic field) of the magnet 17 detected by the magnetic sensor element 21 of the magnetic sensor 15 changes. The magnetic sensor 15 converts the change in the magnetic code into an electrical signal through the magnetic sensor element 21. Based on this electrical signal, it generates an output signal indicating, for example, the absolute rotation angle, and transmits it through the connector 22.

[0057] like Figure 1 As shown, calibrating the magnetic sensor 15 while the magnetic rotation sensor 2 is attached to the rolling bearing 1 allows for more accurate rotation angle detection. This eliminates the tedious steps of assembling the rolling bearing into a machine, such as separating the magnetic rotation sensor from the rolling bearing 1 and calibrating the magnetic sensor, when the rotation angle is actually detected.

[0058] In addition, if Figure 3 、 Figure 4 As shown, protection circuits 21a and 21b are also mounted on the circuit board 20 to attenuate or block harmful external electrical noise. Examples of protection circuits 21a and 21b include common-mode filters, single-mode filters, resistors, ceramic capacitors (capacitors), coils, varistors, inductors, ceramic filters, EMI filters, and ferrite beads. For example, the technologies disclosed in Japanese Patent Application Publication Nos. 2007-240486 and 2007-292678 can be used as these protection circuits 21a and 21b. The need for, type of, number of protection circuits, and location of the protection circuits can be determined appropriately based on the required noise immunity level. For example, to provide resistance to magnetic sensor element 21 itself, an integrated circuit in which one or more protection circuits 21a and 21b are packaged as part of magnetic sensor element 21 can be used. In this case, the effect on the circuit board 20 is weak, and therefore, in order to enhance this, electronic components of the protection circuit may be soldered to the circuit board 20 separately from the magnetic sensor element 21 .

[0059] The circuit board 20 has a ground electrode 20a for releasing electrical noise to the outside. The ground electrode 20a is located at the other side of the axial direction of the circuit board 20 (at Figure 4 A portion of the plate surface (lower side in the center) protrudes slightly axially toward the other side and directly contacts cutout 18. This connects ground electrode 20a to outer ring 4, a conductor. Because outer ring 4 is mated to housing 101, which serves as the main ground element, magnetic sensor 15 is grounded via outer ring 4.

[0060] Furthermore, if the structure is such that there is no electrical continuity between the mating portion of the outer ring 4 and the housing 101, it is sufficient to connect the outer ring 4 to the machine ground using an electrical wire. Furthermore, to strengthen the insulation between the outer ring 4 and the portion of the circuit board 20 other than the ground electrode 20a, an insulating adhesive can be used as the adhesive 23, or an insulating sheet can be placed between the circuit board 20 and the cutout 18.

[0061] The magnetic sensor 15 is fixed to the other side of the axial direction of the circuit substrate 20 (at Figure 1 The plate surface (left in the center) is bonded to the cutout 18 of the outer ring 4, thereby being directly mounted thereon. The magnetic sensor 15 is protected by a resin mold 24 that fills the cutout 18. Alternatively, the resin mold 24 may be omitted or covered with a protective sheet.

[0062] like Figure 1 、 Figure 3 、 Figure 4As shown, the portion of the magnetic sensor 15 that is axially opposed to the magnetic ring 16 is all arranged on the other side of the width surface 9a of the outer ring 4 in the axial direction (at Figure 1 The middle is the left, Figure 4 The middle is the lower side.

[0063] like Figure 5 、 Figure 6 As shown, the cutout portion 18 for realizing such an arrangement is formed to extend from the second circumferential surface 13 of the outer ring 4 toward the bearing center axis O and to face one axial direction (at Figure 6 The notch 18 is groove-shaped and open on one side (upper side). The notch 18 has a concave bottom surface 18a formed as a flat surface along an imaginary plane perpendicular to the axial direction, and two end surfaces 18b, 18b extending in the axial direction. The end surfaces 18b, 18b are formed as flat surfaces along an imaginary plane that bisects the groove width Wn of the notch 18.

[0064] The axial height Hb of the magnetic sensor 15 relative to the notch 18 (see Figure 4 ) is preferably the axial depth dn of the cutout 18 (refer to Figure 6 ). The axial height Hb of the magnetic sensor 15 is the axial height of the magnetic sensor 15 (circuit board 20 and magnetic sensor element 21) relative to the cutout 18 in the area axially overlapping the cutout 18. The depth dn of the cutout 18 is the axial depth from the width surface 9a of the outer ring 4 to the concave bottom surface 18a of the cutout 18. As shown in the example shown, when a resin molded portion 24 is provided, the depth dn of the cutout 18 can be set to accommodate the entire portion axially opposing the magnetic ring 16 and the resin molded portion axially covering this portion within the cutout 18. If the axial height Hb exceeds 95% of the axial depth dn, there is a risk that the resin molded portion 24 will protrude from the cutout 18.

[0065] In addition, if Figure 1 As shown, the cutout 18 is formed so as not to interfere with the raceway surface 11a of the outer ring 4. Specifically, the cutout 18 is formed only on one side of the intersection of the line of action L1 of the load of the rolling element 5 and the raceway surface 11a at the contact portion P1 and the second circumferential surface 13 of the outer ring 4 in the axial direction (at Figure 1 The portion on the right side of the line of action L1.

[0066] The line of action L1 corresponds to the imaginary straight line that defines the contact angle θ between the rolling elements 5 of the rolling bearing 1 and the raceway surfaces 10a and 11a of the two raceway rings 3 and 4. The rolling bearing 1 supports loads in the axial direction and is therefore typically used with an axial preload. As shown in the example shown, when the rolling bearing 1 is a deep groove ball bearing, the preload is low, similar to that of a wave washer, resulting in a contact angle θ of at least 5° and no more than 20°. The notch 18 is formed so as not to lie on the line of action L1 when the contact angle θ is 20°.

[0067] Furthermore, it is preferable to form the cutout 18 on at least the outer diameter side of the outer ring 4. Forming the cutout only on the inner diameter side of the outer ring 4 shortens the radial dimension of the cutout, thereby reducing the space required to accommodate the radially long circuit board 20. Furthermore, forming the cutout 18 on at least the outer diameter side of the outer ring 4 allows the cutout 18 to open radially outward, allowing the connector 22 to extend radially outward from the outer ring 4.

[0068] In the example shown, the cutout 18 is formed up to the portion that overlaps the raceway surface 11a of the outer ring 4 in the axial direction. However, from the perspective of supporting axial loads, it is preferable to limit the cutout to a region that does not overlap the raceway surface 11a of the outer ring 4 in the axial direction. Figure 2 Considering the cross section shown, the boundary of this region is on an axial straight line passing through the radially deepest deepest portion P2 of the raceway surface 11 a of the outer ring 4 .

[0069] In addition, from the viewpoint of supporting the axial load, it is preferable to form a plurality of outer rings 4 on the axial side relative to the raceway surface 11a (in the Figure 2 A notch 18 is formed at an end P3 (right in the middle) on one axial side.

[0070] like Figures 3 to 6 As shown, the width Wb of the portion of magnetic sensor 15 disposed within cutout 18 is preferably no greater than 95% of the groove width Wn of cutout 18. When resin molded portion 24 is provided, as shown in the example, groove width Wn of cutout 18 can be set to accommodate the entire portion disposed within cutout 18 and the thickness of the resin molded portion between this portion and end surfaces 18b, 18b on both sides. If width Wb exceeds 95% of groove width Wn, the gap between magnetic sensor 15 mounted on concave bottom surface 18a of cutout 18 and end surfaces 18b becomes too narrow, making it difficult for the resin molded portion to spread.

[0071] The cutout 18 is formed at only one point in the circumferential direction. The circumferential range of the cutout 18 can be defined by the angle α around the bearing center axis O. The circumferential range α of the cutout 18 can be set to a range of 120° or less. Figure 1) applies a load, and the radial load-bearing ring can ensure the fit between the outer ring 4 and the housing 101 over the entire width of the outer ring 4, and the outer ring 4 can be stably supported by the housing 101.

[0072] Notch 18 is formed in outer ring 4 to ensure sufficient hardness for mounting and supporting magnetic sensor 15. Specifically, outer ring 4 is typically made of a steel material such as bearing steel or case-hardened steel. The hardness of notch 18 formed in such a steel material is HRC 50 or higher, preferably HRC 55 or higher.

[0073] The bearing with a rotation sensor is as described above, comprising: a rolling bearing 1 having an inner ring 3, an outer ring 4, and a plurality of rolling elements 5; and a magnetic rotation sensor 2 for detecting the relative rotational motion of the inner ring 3 and the outer ring 4, wherein the magnetic rotation sensor 2 comprises a magnetic sensor 15 and a magnetic ring 16, wherein the magnetic sensor 15 is mounted on the outer ring 4, which is a raceway of one of the inner ring 3 and the outer ring 4, and the magnetic ring 16 is mounted on the inner ring 3, which is a raceway of the other of the inner ring 3 and the outer ring 4, and the magnetic ring 16 comprises a magnet 17 that is magnetized alternately with different polarities in the circumferential direction, and the magnet 17 is axially oriented on one side (in the axial direction) relative to the magnetic sensor 15. Figure 1 The position on the (right) side is opposite to the magnetic sensor 15 in the axial direction.

[0074] The bearing with a rotation sensor, in particular, the outer ring 4 as one of the raceway rings has a width surface 9a located at one of the two ends defining the width of the outer ring 4 in the axial direction (at Figure 1 and the cutout portion 18, axially from the width surface 9a to the other side (in Figure 1 The magnetic sensor 15 is mounted on the cutout portion 18, thereby utilizing the axial depth dn (refer to the cutout portion 18) of the width surface 9a. Figure 6 ) to move the magnetic sensor 15 axially to the other side (in Figure 1 The magnetic ring 16 is arranged close to the left side (ie, the center side of the width of the bearing with the rotation sensor), and the magnetic ring 16 can also be arranged to the other side (in the axial direction) by the amount of closeness. Figure 1 Therefore, by installing the magnetic sensor 15 in the cutout portion 18, it is necessary to move the magnetic sensor 15 in the axial direction from the width surface 9a (in the left direction). Figure 1 Compared to the structure of Patent Document 1 in which the magnetic sensor is arranged at a position away from the side (right in the middle), the axial position of the magnetic sensor 15 and the magnetic ring 16 is set closer to the other axial side (in the middle). Figure 1 The left side is in the center), so the bearing with a rotation sensor is further miniaturized in the axial direction.

[0075] Therefore, according to the bearing with a rotation sensor, the magnet 17 of the magnetic ring 16 and the magnetic sensor 15 can be aligned with the rolling bearing 1 in one axial direction (in the direction of rotation). Figure 1The magnet 17 is located on one side of the axial direction (in the right direction) relative to the magnetic sensor 15. Figure 1 The bearing with a rotation sensor (center, right) is further miniaturized in the axial direction. Furthermore, using this bearing with a rotation sensor makes it easier to reduce the space occupied by the rolling bearing and magnetic rotation sensor within the machine, particularly in the axial direction, compared to using rolling bearings, magnetic rings, and magnetic sensors separately. This allows for a more compact and lightweight machine, resulting in energy-saving operation, improved handling, a wider range of motion, shorter positioning time, and improved responsiveness due to increased shaft torsional rigidity.

[0076] Furthermore, the bearing with a rotation sensor can securely and productively attach the magnetic sensor 15 to the outer ring 4 (notch portion 18 ) serving as one raceway ring by attaching the magnetic sensor 15 to the outer ring 4 serving as one raceway ring.

[0077] Furthermore, in this bearing with a rotation sensor, the magnetic sensor 15 includes a ground electrode 20a connected to the outer ring 4, which serves as one of the raceways. This allows the outer ring 4, serving as one of the raceways, to be effectively used as the bearing's main ground. Furthermore, there is no need to install a separate ground line between the magnetic sensor 15 and the machine's main ground, allowing for a corresponding reduction in the size of the machine.

[0078] In addition, in the bearing with a rotation sensor, the magnetic ring 16 has a metal core 19 formed into an annular shape by a magnetic body, and the metal core 19 has a width surface 9a of the outer ring 4 arranged on one side in the axial direction (at the same direction as the width surface of the raceway ring). Figure 1 The magnet 17 is fixed to the cover portion 19b on the other axial side (in the middle) of the cover portion 19b. Figure 1 The left side is in the center), thereby blocking the magnetic field (external leakage magnetic field) flowing in from the metal core 19 side of the magnetic ring 16 and protecting the magnetic field generated by the magnet 17 of the magnetic ring 16 (preventing magnetic field disturbance).

[0079] Furthermore, in this bearing with a rotation sensor, since one raceway is formed by the outer ring 4, the outer diameter Dm of the magnetic ring 16 is smaller than the outer diameter Do of the outer ring 4. This makes it easier to insert the bearing with a rotation sensor into the machine housing 101. This can further improve the productivity and safety of machine assembly.

[0080] In addition, in the bearing with a rotation sensor, the outer ring 4 as one of the raceway rings has: a first circumferential surface 11, including a contact portion P1 with the rolling element 5 and extending between the two ends of the outer ring 4; and a second circumferential surface 13 extending between the two ends of the outer ring 4 on the side opposite to the first circumferential surface 11 in the radial direction, and the notch 18 is formed only on the axial side (at the intersection of the line of action L1 of the load at the contact portion P1 and the second circumferential surface 13) Figure 1 As a result, there is no cutout 18 on the load action line L1 at the contact portion P1 between the outer ring 4 of the raceway ring and the rolling element 5, thereby avoiding a reduction in the rigidity of the outer ring 4 of the raceway ring with respect to the load.

[0081] In addition, in the bearing with a rotation sensor, the portion of the magnetic sensor 15 that is axially opposed to the magnetic ring 16 is entirely arranged on the width surface 9a of the outer ring 4, which is the width surface of the raceway ring, on the axial other side (at the Figure 1 The magnetic ring 16 can be arranged as close as possible to the width surface 9a of the width surface of the raceway ring on one side without being hindered by the magnetic sensor 15, so that the space occupied by the circuit substrate 20 and the magnetic sensor element 21 forming the opposing portion can be accommodated within the width of the rolling bearing 1 to miniaturize the bearing with the rotation sensor, especially in the axial direction.

[0082] In the first embodiment, as a means of directly attaching the magnetic sensor 15 to the cutout portion 18, bonding is adopted, but it can also be changed to screw fastening. As an example of the second embodiment, Figure 7 、 Figure 8 In addition, only the differences from the first embodiment will be described below.

[0083] In the second embodiment, the circuit board 20 is provided with two or more axially extending through-holes 20b. Furthermore, internally threaded holes 31a are formed in the cutouts 31 in positions corresponding to the through-holes 20b. A headed externally threaded member 32 is passed through each of the through-holes 20b and screwed into the internally threaded holes 31a, thereby securing the circuit board 20 to the cutouts 31 in the axial direction.

[0084] The inner periphery of at least one through-hole portion 20b serves as a ground electrode in contact with the externally threaded member 32. The externally threaded member 32 is formed of a conductive material such as metal. Therefore, the inner periphery of the through-hole portion 20b, serving as the ground electrode, is indirectly connected to the notch portion 31 via the externally threaded member 32.

[0085] The bearing with a rotation sensor according to the second embodiment is mounted by threading the magnetic sensor (circuit board 20) onto the outer ring (notch 31) of one raceway ring. This allows for reliable and productive mounting of the magnetic sensor on the outer ring of one raceway ring. Furthermore, the outer threaded member 32 used for threading connects the inner circumference of the through-hole 20b, which serves as the ground electrode, to the notch 31 of the outer ring.

[0086] In the first and second embodiments, the magnetic sensor is directly mounted on the cutout portion, but it can also be mounted indirectly using a bracket. Figure 9 shown.

[0087] The bearing with a rotation sensor according to the third embodiment further includes a sensor housing 40, which is directly mounted on the outer ring 4, which is one of the raceways. The sensor housing 40 is composed of a sensor bracket 41, a mounting ring 42, an outer cylinder 43, and a cover 44. The sensor bracket 41 is arranged in the cutout 18, the mounting ring 42 is inserted into the outer ring 4, and the outer cylinder 43 is arranged to surround the magnetic ring 16 and extend from the outer ring 4 to one side in the axial direction (at the Figure 9 The cover 44 blocks one axial direction of the outer cylinder 43 (in the right direction). Figure 9 The sensor bracket portion 41 is supported in the axial direction by the concave bottom surface of the cutout portion 18 in the cutout portion 18. The sensor bracket portion 41, the mounting ring portion 42 and the outer cylinder portion 43 are composed of a seamless, integral outer ring component formed by stamping. The cover 44 is composed of a cap component formed by stamping and is combined with the outer cylinder portion 43. The sensor housing 40 is fixed to the outer ring 4 by press-fitting the mounting ring portion 42 relative to the outer ring 4. The magnetic sensor 15 is fixed to one axial side of the sensor bracket portion 41 (at Figure 9 The middle is the right side.

[0088] The entire sensor housing 40 is formed of a magnetic body.

[0089] In the bearing with a rotation sensor according to the third embodiment, the magnetic sensor 15 is indirectly mounted by fitting the sensor housing 40 relative to the outer ring 4 of the raceway ring on one side, thereby enabling the magnetic sensor 15 to be reliably and productively mounted on the outer ring 4 of the raceway ring on one side.

[0090] In addition, you can also Figure 4 、 Figure 6 Such a structure allows the ground electrode of the circuit board 20 to contact the sensor holder 41 of the sensor housing 40 as a conductor. Through this contact, the outer ring 4 and the ground electrode can also be connected via the sensor holder 41 .

[0091] In the third embodiment, the width of the bearing with a rotation sensor is greater than in the first embodiment, but the sensor housing 40 also offers the advantage of holding the magnetic sensor 15. Specifically, the sensor housing 40 not only holds the magnetic sensor 15 but also serves the purpose of preventing lubricant in the rolling bearing from passing toward the magnetic sensor 15 by extending the sensor holder 41 and mounting ring 42 toward the inner ring 3 of the other raceway. Furthermore, a metal sensor housing 40 protects the magnetic sensor 15 and magnetic ring 16. Particularly when the sensor housing 40 is formed from a magnetic material, it further protects the magnetic sensor 15 and magnetic ring 16 from external magnetic fields. Furthermore, sealing the sensor housing 40 with a cover 44 prevents the intrusion of dust from the outside.

[0092] In addition, as the sensor housing 40, a housing made of metal sheet formed by stamping is illustrated, but the metal sensor housing 40 has difficulties in processability, so it is sometimes difficult to cope with the situation where it has to be formed into a complex shape for the purpose of holding the magnetic sensor, etc. In this case, a resin material can also be used. If it is a resin material, it has good processability, so in addition to being able to cope with complex shapes, it also has the advantage of being lightweight. In addition, the case where the sensor housing is composed of an outer ring component and a cap component is illustrated, but it can also be composed of a single component. In the case where the sensor housing is composed of multiple components, it can also be composed of a combination of metal sheet components such as magnetic bodies and resin components. In addition, the outer ring component can be divided into a main body and a sensor bracket part, and each can be assembled as a single unit to the raceway ring on one side. It can also be assembled by inserting the sensor bracket part after the main body is assembled.

[0093] In the first to third embodiments described above, the raceway ring on one side, on which the magnetic sensor is to be installed, is set as the outer ring, and the raceway ring on the other side, on which the magnetic ring is to be installed, is set as the inner ring. However, in the case where the outer ring is used as the rotating ring and the inner ring is used as the stationary ring, it is sufficient to install the magnetic sensor by installing the magnetic ring on the outer ring and forming a cutout portion on the inner ring. Therefore, the illustration is omitted.

[0094] The embodiments disclosed herein are illustrative in all respects and should not be construed as restrictive. The scope of the present invention is not defined by the above description but by the scope of the claims for protection of this application, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims for protection of this application.

[0095] Description of Reference Numerals

[0096] 1…rolling bearing; 2…magnetic rotation sensor; 3…inner ring; 4…outer ring; 5…rolling element; 8a, 8b, 9a, 9b…width surface; 10, 11…first peripheral surface; 12, 13…second peripheral surface; 15…magnetic sensor; 16…magnetic ring; 17…magnet; 18, 31…cutout portion; 19…metal core; 19b…cover portion; 20…circuit board; 20a…ground electrode; 20b…through hole portion; 21…magnetic sensor element; 23…adhesive; 31a…inner threaded hole portion; 32…external threaded component; 40…sensor housing; 41…sensor bracket portion; 42…mounting ring portion.

Claims

1. A bearing with a rotation sensor, comprising: A rolling bearing having an inner ring, an outer ring and a plurality of rolling elements; and A magnetic rotation sensor detects the relative rotational motion between the inner ring and the outer ring, The magnetic rotation sensor has: a magnetic sensor mounted on a raceway ring of one of the inner ring and the outer ring; and A magnetic ring is mounted on the raceway ring of the other of the inner ring and the outer ring. The magnetic ring has magnets that are alternately magnetized into different poles in the circumferential direction. The magnet is located on one side of the magnetic sensor in the axial direction and faces the magnetic sensor in the axial direction. The bearing with a rotation sensor is characterized in that: The one raceway ring has: a width surface located at one end portion of the two ends defining the width of the one raceway ring; and a notch portion recessed from the width surface toward the other axial side. The magnetic sensor is mounted on the cutout portion.

2. The bearing with a rotation sensor according to claim 1, characterized in that: The magnetic sensor is mounted on the one raceway ring by bonding, screwing, or fitting.

3. The bearing with a rotation sensor according to claim 1 or 2, characterized in that: The magnetic sensor includes a ground electrode connected to the one raceway ring.

4. The bearing with a rotation sensor according to any one of claims 1 to 3, characterized in that: The magnetic ring has a metal core formed into a ring shape by a magnetic body. The metal core includes a cover portion disposed on one axial side relative to the width surface of the one raceway ring. The magnet is fixed to the other axial side of the cover portion.

5. The bearing with a rotation sensor according to any one of claims 1 to 4, characterized in that: The raceway ring of one side is composed of the outer ring, The outer diameter of the magnetic ring is smaller than the outer diameter of the outer ring.

6. The bearing with a rotation sensor according to any one of claims 1 to 5, characterized in that: The raceway ring of one of the two ends has: a first circumferential surface including a contact portion with the rolling element and extending between the two ends; and a second circumferential surface extending between the two ends on a side opposite to the first circumferential surface in a radial direction. The notch portion is formed only at a portion located on one axial side of an intersection of a line of action of a load at the contact portion and the second peripheral surface.

7. The bearing with a rotation sensor according to any one of claims 1 to 6, characterized in that: All portions of the magnetic sensor that face the magnetic ring in the axial direction are arranged on the other axial side relative to the width surface of the one raceway ring.

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