Bearing with sliding target and associated sensor

Abstract

The bearing comprises a first ring (10) and a second ring (12) which are rotatable concentrically relative to each other, at least one annular groove (50) being formed on the second ring (12) and oriented toward the first ring (10). The bearing further comprises: at least one target element (52) engaged in the groove (50) of the second ring and freely slidable in the circumferential direction in the groove, the target element (52) protruding into a hole (54) formed on the first ring (10), so that the first ring prevents the target element from rotating when the second ring rotates and the first ring is fixed, and at least one sensor (24) mounted on the first ring and facing the target element (52) to detect the axial position of the target element.

Description

Technical Field

[0001] The present invention relates to the field of bearings.

[0002] The invention relates in particular to the field of large diameter rolling bearings which are able to accommodate axial loads and radial loads and have an inner ring and an outer ring which are arranged concentrically around an axis of rotation extending in the axial direction. Background Art

[0003] Such large-diameter rolling bearings can be used, for example, in tunnel boring machines, mining machines or wind turbines.

[0004] Large diameter rolling bearings include two concentric inner and outer rings and at least two rows of rolling elements, such as rollers, arranged between the inner and outer rings. Such rolling bearings are usually loaded in both axial and radial directions, often with relatively large loads. In this case, reference is made to orientation roller bearings or slewing roller bearings.

[0005] Due to the heavy loads, the components of the rolling bearing, more particularly the raceways of the rolling elements, wear. The wear of the rings and rolling elements leads to a significant increase in the initial bearing clearance. Wear exceeding a certain value can lead to severe bearing failure.

[0006] Measuring bearing wear through the increase in clearance (causing relative axial and radial displacement of the rings) helps predict the remaining life of the bearing.

[0007] This unwanted movement affects the correct function of the bearing and the application, with the risk of the bearing rings touching and colliding. Other elements attached to the bearing rings may also collide.

[0008] It is common to replace bearings when they are worn. Such maintenance interventions are expensive, especially because the machine or facility needs to be shut down. It is therefore desirable to perform such maintenance interventions in a timely manner, but not too early, before any contact occurs between the bearing rings.

[0009] In order to monitor the bearing condition during the service life of the bearing, the rolling bearing disclosed in patent application FR-A1-3041396 comprises an annular magnetic target fixed to the inner ring and a sensor mounted on the outer ring and facing the magnetic target. Thus, the axial relative movement and the angular relative movement between the inner ring and the outer ring can be detected.

[0010] However, this requires the annular magnetic target to be mounted on an inner ring which may be several meters in diameter.

[0011] Reference may also be made to a rolling bearing disclosed in patent US-B2-10041545 and comprising an encoder provided with a magnetic strip portion attached in a flat manner against the outer ring and cooperating with a sensor fixed to the inner ring.

[0012] However, with this configuration, the axial relative movement between the inner and outer rings cannot be measured without taking into account the rotational position of the rings, but only when the outer ring is in a rotational position where the magnetic strip portion is located in front of the sensor of the inner ring. Summary of the invention

[0013] An object of the present invention is to overcome these disadvantages.

[0014] The invention relates to a bearing comprising a first ring and a second ring which are rotatable concentrically relative to each other.

[0015] According to general characteristics, at least one annular groove is formed on the second ring and is oriented towards the first ring.

[0016] According to another general feature, the bearing further comprises at least one target element engaged in a groove of the second ring and freely slidable in the groove in a circumferential direction relative to the second ring. The target element projects into a hole formed on the first ring, so that the first ring prevents the target element from rotating when the second ring rotates and the first ring is fixed.

[0017] The bearing further comprises at least one sensor mounted on the first ring and facing the target element to detect the axial position of the target element. The target element is fixed relative to the second ring in the axial direction. An axial gap is provided between the target element and the wall of the hole of the first ring.

[0018] Thanks to the invention, the axial relative displacement between the rings (first and second) can be detected accurately, whatever the rotational position of the rings. In fact, the axial position of a gliding target moving axially with the second ring is detected by the sensor. Furthermore, it is not necessary to mount an annular magnetic target on one of the rings. The groove for the engagement of the target element can be easily machined on the associated ring.

[0019] Advantageously, the target element is provided with a target having a track coded in the axial direction and facing the sensor. The target element may also be provided with a target holder engaging in the groove of the second ring and supporting the target.

[0020] In one embodiment, the longitudinal axis of the sensor is perpendicular to the axis of the bearing.

[0021] Advantageously, the sensor is arranged in a hole of the first ring. The hole may extend radially from an axial cylindrical surface of the first ring radially facing the second ring and open on an opposite axial cylindrical surface radially located on the side opposite to the second ring. Thus, the sensor can be inserted into the through hole in a simple manner and arranged in its final position. The first ring may also include a plug sealing the hole.

[0022] Preferably, the sensor is held at a fixed distance from the target element.

[0023] In one embodiment, the sensor is in radial contact with the target element. The bearing may further comprise a prestressing element arranged between the first ring and the sensor to maintain contact between the sensor and the target element. The prestressing element applies a permanent force on the sensor to ensure radial contact between the sensor and the target element, in particular in the case of relative radial displacement between the rings (the first ring and the second ring). The prestressing element may comprise a spring.

[0024] In another embodiment, the sensor is spaced apart from the target element in radial direction. In this case, the sensor faces the target element in radial direction without contacting it.

[0025] In a particular embodiment, the bearing may further comprise a guideway fixed in the hole of the first ring, a sliding frame mounted on the guideway and capable of moving radially relative to the first guideway, and the sensor fixed to the sliding frame, the additional sensor being arranged on one of the sliding frame and the guideway and being adapted to detect the axial position of the sliding frame relative to the guideway, and a prestressing element for maintaining radial contact between the target element and the groove. In this particular embodiment, the sensor is in radial contact with the target element. The prestressing element may be arranged radially between the guideway and the sliding frame.

[0026] Therefore, the radial relative displacement between the rings (the first ring and the second ring) can also be detected by utilizing the radial position of the carriage supporting the sensor relative to the guide rail.

[0027] In one embodiment, the bearing further comprises at least one row of rolling elements arranged between raceways provided on the first ring and the second ring.

[0028] The bearing may further comprise a first seal and a second seal which are arranged between the first ring and the second ring and which together define a closed rolling space inside which the row of rolling elements, the sensor and the target element are accommodated.

[0029] In one embodiment, the bearing may comprise at least one additional seal which is located inside the closed rolling space and which delimits, together with one of the first seal and the second seal, a closed detection space which opens into the groove.

[0030] In one embodiment, the bearing includes at least one row of axial rolling elements arranged between radial raceways provided on the first ring and the second ring, and at least one row of radial rolling elements arranged between axial raceways provided on the first ring and the second ring, the second ring including a protruding nose, the protruding nose engaging in the annular groove of the first ring and protruding radially from the axial cylindrical surface of the second ring, the groove being formed on the axial cylindrical surface.

[0031] The term "axial rolling element" is understood to mean a rolling element adapted to accommodate axial loads, whereas the term "radial rolling element" is understood to mean a rolling element adapted to accommodate radial loads.

[0032] The nose of the second ring may also be provided with two oppositely facing radial flanks axially delimiting the axial cylindrical surface, one of the radial flanks at least partially delimiting the radial raceway of the second ring.

[0033] In one embodiment, the bearing comprises at least two rows of axial rolling elements respectively arranged between radial raceways provided on the first ring and the second ring, and the at least two rows of axial rolling elements are axially arranged on both sides of the nose of the second ring.

[0034] In one embodiment, the sensor may be a magnetic sensor, an inductive sensor, or an optical sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention and its advantages will be better understood by studying the detailed description of a particular embodiment given by way of non-limiting example and illustrated by the accompanying drawings, in which:

[0036] - Figure 1 is a partial cross section of a rolling bearing according to a first example of the present invention,

[0037] - Figure 2 yes Figure 1 Details of the

[0038] - Figure 3 is a partial cross section of a rolling bearing according to a second example of the present invention. DETAILED DESCRIPTION

[0039] like Figure 1 The rolling bearing shown is a large diameter rolling bearing comprising a first ring 10 and a second ring 12. In the example shown, the first ring 10 is an outer ring and the second ring 12 is an inner ring. In this example, the inner ring 12 is a rotating ring and the outer ring 10 is a non-rotating ring. The rolling bearing can be used, for example, in tunnel boring machines, wind turbines or any other application using large diameter rolling bearings.

[0040] The outer ring 10 and the inner ring 12 are concentric and extend axially along a bearing rotation axis XX' extending in the axial direction. The rings 10, 12 are of solid type.

[0041] The outer ring 10 is formed as a split ring and includes a first ring 14 and a second ring 16 stacked relative to each other in the axial direction. Each of the first ring 14 and the second ring 16 of the outer ring is provided with a plurality of aligned through holes (not shown) for engagement by assembly bolts.

[0042] In the example shown, the rolling bearing comprises two rows of axial rollers 18 , 20 arranged between the outer ring 10 and the inner ring 12 to form an axial thrust, and one row of radial rollers 22 arranged between the outer ring 10 and the inner ring 12 to form a radial thrust.

[0043] As will be described later, the rolling bearing further comprises a sensor 24 for detecting an axial relative displacement between the outer ring 10 and the inner ring 12. In the example shown, the sensor 24 is mounted on the outer ring 10.

[0044] The rollers 18, 20, 22 in a row are identical to one another. Each roller 18, 20, 22 comprises a cylindrical outer rolling surface and two opposite front end surfaces delimiting the outer rolling surface. The axis of rotation of each roller 22 is parallel to the axis XX' of the bearing and perpendicular to the axis of each roller 18, 20. In the example shown, the axial length of the roller 18 is greater than the axial length of the roller 20. As another option, the axial length of the roller 18 may be less than or may be equal to the axial length of the roller 20.

[0045] The rollers 18 are axially arranged between annular radial raceways 26, 28 formed respectively on the inner ring 12 and the outer ring 10. Each radial raceway 26, 28 has a straight inner profile in cross section that contacts the rolling surface of the rollers 18. The raceways 26, 28 face each other in the axial direction.

[0046] The rollers 20 are arranged axially between annular radial raceways 30, 32 formed on the inner ring 12 and the outer ring 10, respectively. Each radial raceway 30, 32 has a straight inner profile in cross section that contacts the rolling surface of the roller 20. The raceways 30, 32 face each other in the axial direction. The rows of rollers 18, 20 are spaced apart from each other in the axial direction.

[0047] The rollers 22 are arranged radially between annular axial raceways 34, 36 formed on the inner ring 12 and the outer ring 10, respectively. Each axial raceway 34, 36 has a straight inner profile in cross section that contacts the rolling surface of the roller 22. The raceways 34, 36 face each other in the radial direction. The row of rollers 22 is staggered ( / offset) radially outward relative to the row of rollers 18, 20. The row of rollers 22 is located axially between the row of rollers 18 and the row of rollers 20.

[0048] The outer ring 10 comprises an annular groove 38 which is open inwardly in the radial direction towards the inner ring 12. The outer ring 10 comprises a stepped inner cylindrical surface or hole 10a, by which the groove 38 is formed. The outer ring 10 also comprises an outer cylindrical surface 10b which is radially opposite ( / opposite) to the hole 10a. The outer ring 10 also comprises two oppositely facing radial front surfaces 10c, 10d which axially delimit the hole 10a and the outer surface 10b of the ring.

[0049] The inner ring 12 comprises an annular projecting nose 40 which engages in the annular groove 38 of the outer ring. The nose 40 extends radially outwards.

[0050] The inner ring 12 comprises an inner cylindrical hole 12a and a stepped outer cylindrical surface 12b radially opposite the hole 12a. In the example shown, the hole 12a of the inner ring is provided with gear teeth (not shown). The inner ring 12 also comprises two radial front surfaces 12c, 12d facing away from each other, which define the hole 12a and the outer cylindrical surface 12b in the axial direction. The protruding nose 40 protrudes radially from the outer cylindrical surface 12b.

[0051] The rows of rollers 18, 20 are arranged axially between the nose 40 of the inner ring and the groove 38 of the outer ring. The rows of rollers 18, 20 are arranged on both sides of the nose 40 of the inner ring. The radial raceway 26 is located on the nose 40 and on the radial portion of the stepped outer cylindrical surface 12b of the inner ring. As another option, the radial raceway 26 can be completely located on the nose 40. The radial raceway 30 is located on the nose 40. The radial raceways 28, 32 are located on the groove 38 of the outer ring.

[0052] More precisely, the first radial side ( / flank) of the nose 40 partially defines the radial raceway 26 for the roller 18. The first radial side of the groove 38, which faces the first radial side of the nose 40 in the axial direction, defines the radial raceway 28 for the roller 18. The second side of the nose 40 and the facing second side of the groove 38 define the radial raceways 30, 32 for the roller 20, respectively. The first and second sides of the nose 40 facing away from each other define the nose in the axial direction. Similarly, the first and second sides of the groove 38 opposite each other define the groove in the axial direction. Each of the first and second sides of the nose 40 extends radially from the outer cylindrical surface 12b of the inner ring.

[0053] The row of rollers 22 is arranged radially between the nose 40 of the inner ring and the groove 38 of the outer ring. The axial raceways 34, 36 are located on the nose 40 and the groove 38, respectively. The outer cylindrical surface of the nose 40 defines the axial raceway 34. The outer cylindrical surface of the nose 40 and the outer cylindrical surface 12b are offset radially. As a result, the axial raceway 34 and the outer cylindrical surface 12b are also offset radially. The outer cylindrical surface of the nose 40 extends axially between the opposite radial sides of the nose.

[0054] The axial bottom of the groove 38 defines the axial raceway 36. In the example shown, an annular slot 41 is formed in the bottom of the groove 38 and defines the axial raceway 36. The axial raceway 36 radially faces the outer cylindrical surface of the nose 40 on which the axial raceway 34 is formed.

[0055] In the example shown, the inner ring 12 is made in one piece. As another option, the inner ring 12 can be divided in the axial direction into at least two separate parts fixed together. In another variant, the nose 40 can be made separately from the main part of the inner ring.

[0056] As mentioned before, the outer ring 10 is divided into two separate parts in the axial direction, namely the first ring 14 and the second ring 16. The first ring 14 and the second ring 16 together define the groove 38. The radial raceway 28 is located on the first ring 14 and the radial raceway 32 is located on the second ring 16 of the outer ring.

[0057] The rolling bearing also comprises annular seals 42, 44 on both sides mounted on the inner ring 12 and arranged to close the radial space existing between the rings 10, 12. This radial space is defined between the bore 10a of the outer ring and the outer cylindrical surface 12b of the inner ring and the outer surface of the nose 40.

[0058] A closed space 46 is defined between the inner and outer rings 12 , 14 and the seals 42 , 44 , and the rows of rolling elements 18 , 20 , and 22 and the sensor 24 are accommodated in the closed space 46 .

[0059] Each seal 42, 44 is installed in a groove (not shown) formed on the outer cylindrical surface 12b of the inner ring and contacts the outer ring 10. The seal 42 contacts the radial front surface 10c of the outer ring. The seal 44 contacts the hole 10a of the outer ring near the row of rollers 18 in the axial direction. As another option, at least one of the seals 42, 44 can be provided with an opposite configuration so that the seal is installed on the outer ring 10 and is in friction contact with the inner ring 12.

[0060] As mentioned above, the sensor 24 is configured to detect the axial relative displacement between the outer ring 10 and the inner ring 12. To this end, an annular groove 50 is also formed on the inner ring 12, and the rolling bearing is provided with a sliding target element ( / target element) 52 engaged in the groove 50. In this example, the sensor 24 contacts the target element 52 in the radial direction.

[0061] In the example shown, the groove 50 is formed on the outer cylindrical surface 12b of the inner ring. The groove 50 extends radially inward from the outer cylindrical surface 12b. The groove 50 is axially bounded by two annular side edges or sidewalls 50a, 50b. The sidewalls 50a, 50b face each other axially. The sidewalls 50a, 50b are spaced apart from each other axially. The groove 50 also includes an annular bottom 50c connected to the sidewalls 50a, 50b. The outer cylindrical surface 12b of the inner ring and the bottom 50c of the groove are radially staggered ( / offset).

[0062] In the example shown, the sidewalls 50a, 50b of the groove extend radially, and the bottom 50c extends axially. The groove 50 has a rectangular cross section. As another option, the groove 50 can have a cross section of other shapes, such as a V-shaped cross section. In this case, the sidewalls 50a, 50b of the groove extend obliquely, and the groove can be provided with or without the bottom 50c. As another option, the groove can include an annular conical bottom connected to one or both radial sidewalls.

[0063] The target element 52 is engaged in the groove 50 and protrudes into the hole 54 formed on the outer ring 10. The target element 52 is in contact with the bottom 50c of the groove in the radial direction. The target element 52 is not annular. The target element 52 has a limited size in the circumferential direction. For example, the target element 52 can extend over an angular portion between 10° and 30°.

[0064] The target element 52 is fixed in the axial direction relative to the inner ring 12. In other words, the target element 52 moves axially together with the inner ring 12. In the example shown, the target element 52 is blocked in the axial direction by the walls 50a, 50b of the groove.

[0065] The target element 52 is freely rotationally movable relative to the inner ring 12 within the groove 50. In other words, the target element 52 is circumferentially glideable within the groove 50 and is fixed to the inner ring 12 in the axial direction for translation therewith.

[0066] As previously described, the target element 52 protrudes into the hole 54 of the outer ring. The target element 52 protrudes radially into the hole 54. The hole 54 faces the groove 50 of the inner ring in the radial direction.

[0067] As in Figure 2 As more clearly shown in FIG. 5 , a first axial gap 56 and a second axial gap 58 are provided between the target element 52 and the inner wall of the hole 54. The first axial gap 56 and the second axial gap 58 are axially provided on both sides of the target element 52. Therefore, the axial dimension of the portion of the target element 52 protruding into the hole 54 is smaller than the axial dimension of the portion of the hole in which the portion of the target element is positioned.

[0068] The hole 54 is sized and shaped to receive the target element 52 and prevent the target element from rotating when the inner ring 12 rotates relative to the outer ring 10. The hole 54 is sized larger than the axial and circumferential dimensions of the portion of the target element 52 that protrudes into the hole.

[0069] The target element 52 is provided with a target holder ( / target holder) 60 engaged in the groove 52 of the inner ring, and a target ( / target) 62 mounted on the target holder and in contact with the sensor 24 in the radial direction.

[0070] The target holder 60 protrudes into the hole 54 of the outer ring. The target holder 60 is blocked by the walls 50a, 50b of the groove in the axial direction. The target holder 60 contacts the bottom 50c of the groove in the radial direction. The target holder 60 has a parallelepiped form. The target holder 60 can be made of metal or plastic.

[0071] In the example shown, the target 62 is located within the outer ring bore 54. Here, the target 26 is mounted on the outer surface of the target holder 60. The target 62 is secured to the target holder 60 by any suitable means. The target 62 has a track that is encoded in the axial direction and oriented radially toward the sensor 24.

[0072] For example, the target 62 is of magnetic type and comprises alternating positive and negative poles. In this case, the track of the target 62 is magnetically encoded by successive positive and negative poles in the axial direction.

[0073] The hole 54 of the outer ring extends from the hole 10a and is formed on the outer surface 10b ( Figure 1 ) is open ( / opening) on ​​the outer ring 10. The sensor 24 is located in the hole 54. In the example shown, the sensor 24 is completely located in the hole 54. As another option, the sensor 24 can protrude radially into the radial space provided between the outer ring 10 and the inner ring 12. Preferably, the shape of the through hole 54 is complementary to that of the sensor 24.

[0074] In the example shown, the hole 54 includes a first portion (not labeled) extending from the hole 10a and into which the target element 52 protrudes, and a second portion (not labeled) extending radially from the first portion and having a reduced size. The sensor 24 is mounted in the second portion of the hole 54 and protrudes radially into the first portion of the hole. Alternatively, the hole 54 may include a single portion.

[0075] The outer ring 10 also includes a plug 64 that closes and seals the hole 54. The plug 64 is radially located in the through hole 54. The plug 64 is fixed inside the through hole 54 by any suitable means (for example, by press fitting). The plug 64 is in contact with the outer cylindrical surface 10b ( Figure 1 ) flush.

[0076] The rolling bearing also includes a spring 66 radially interposed between the plug 64 and the sensor 24. The spring 66 exerts a radial prestressed permanent force on the sensor 24 to ensure constant contact between the sensor 24 and the target element 52. The spring 66 also ensures that the contact between the bottom 50c of the groove and the target element 52 is maintained.

[0077] The spring 66 serves as a prestressing element. A first end of the spring 66 bears against the plug 64, and an opposite second end bears against the sensor 24. In the example shown, the spring 66 is a compression spring. As another option, other prestressing elements may be provided to exert a permanent force on the sensor 24, for example, other prestressing elements are elastic washers, such as Belleville washers.

[0078] The sensor 24 includes a sensor body 70 mounted inside the through hole 54 of the outer ring. The sensor body 70 is fixed inside the through hole 54 by any suitable means (for example, by press fitting). The sensor body 70 contacts the target element 52 in the radial direction, that is, contacts the target 62. The sensor 24 can be a linear absolute sensor.

[0079] In the disclosed example, the sensor 24 also includes an output connection cable 72 for transmitting sensed data, and the output connection cable 72 extends outward relative to the sensor body 70. The output cable 72 extends radially outward. The plug 64 is provided with a through hole (not shown) through which the output cable 72 can pass. The output cable 72 connects the sensor 24 to a control unit (not shown) of the rolling bearing to transmit the sensed measurement value. As another option, in the case of a wireless sensor, the sensor 24 may not have such an output cable.

[0080] The sensor body 70 of the sensor has a longitudinal axis 74 extending in the radial direction. The axis 74 also forms the longitudinal axis of the sensor 24. The axis 74 is perpendicular to the axis XX' ( Figure 1 ). Axis 74 is perpendicular to the trajectory of target 62 of the target element.

[0081] The sensor 24 is capable of detecting a magnetic field generated by a target element 62. For example, the sensor 24 may be a Hall Effect sensor, for example.

[0082] As previously mentioned, in this example, the inner ring 12 rotates while the outer ring 10 remains stationary. During the rotation of the inner ring 12, the wall of the hole 54 of the outer ring prevents the target element 52 from rotating. Therefore, the inner ring 12 rotates relative to the target element 52 and the outer ring 10.

[0083] When the inner race 12 is axially displaced relative to the outer race, this results in a corresponding axial displacement of the target element 52 relative to the sensor 24 , which is detected by the sensor 24 .

[0084] In fact, the sensor 24 emits a signal corresponding to the magnetic encoding of the track of the target 62 of the target element. A control unit connected to the sensor calculates a corresponding value of the axial displacement of the inner ring 12 relative to the outer ring 10.

[0085] The axial gaps 56 , 58 provided between the target element 52 and the inner wall of the hole 54 can avoid axial contact between the target element and the outer ring 10 when the inner ring 12 moves in the axial direction.

[0086] Refer again Figure 1 In the example shown, the rolling bearing further comprises an additional seal 80 disposed inside the closed space 46 defined by the seals 42, 44. The seal 80 is located axially near the seal 42. The seal 80 is arranged axially between the seal 42 and the row of axial rollers 20. In the example shown, the seal 80 is mounted in a groove (not shown) formed on the outer cylindrical surface 12b of the inner ring and is in contact with the outer ring 10. The seal 80 is in contact with the hole 10a of the outer ring near the hole 54. As another option, the seal 80 can be mounted on the outer ring 14 and in frictional contact with the inner ring 12.

[0087] The seal 80 is radially between the outer ring 10 and the inner ring 12, and defines a closed detection space (not shown) together with the seal 42, the interior of the detection space leading to the groove 50 of the inner ring and the hole 54 of the outer ring. Only the groove 50, the hole 54, the target element 52 and the sensor 24 are located inside the detection space. There is no roller row inside the detection space. This reduces the risk of contaminants such as grease ( / oil), dust, and water reaching the sensor 24.

[0088] Figure 3 The shown example differs from the first example primarily in that the target element 52 has a different design. Here, the target holder 60 of the target element has a T-shaped cross section.

[0089] In this example, the target retainer 60 radially abuts against a radial shoulder of the hole 54, which is foreseen to radially retain the target element 52 inside the hole. Here, in the case of radial displacement of the inner ring 12 relative to the outer ring 10, a radial gap (not shown) is provided between the target retainer 60 and the bottom 50c of the groove.

[0090] In this example, the target 62 of the target element also has a track that is encoded in the axial direction and oriented radially toward the sensor 24. The target 62 can be of magnetic type and the sensor 24 can be a linear absolute value sensor. In this example, a small radial gap is provided between the target 62 and the sensor 24. As another option, the target 62 can be in contact with the sensor 24 in the radial direction.

[0091] Similar to the first example, when the inner ring 12 rotates, the wall of the hole 54 of the outer ring prevents the target element 52 from rotating. Therefore, the inner ring 12 rotates relative to the target element 52 and the outer ring 10.

[0092] When the inner ring 12 is axially displaced relative to the outer ring, this results in a corresponding axial displacement of the target element 52 relative to the sensor 24, which is detected by said sensor.

[0093] In the example shown, the groove 50 is formed on the outer cylindrical surface 12b of the inner ring axially between the row of axial rollers 20 and the seal 42. As another alternative, depending on the design of the rolling bearing, the groove 50 may be provided on another region of the outer cylindrical surface 12b, or on the outer cylindrical surface of the nose 40 of the inner ring on which the axial raceway 34 is formed. In this latter case, the sensor 24 is axially located between the row of radial rollers 22 and the row of axial rollers 20 or 18.

[0094] In the example shown, the target element 62 and the sensor 24 use magnetic technology. Alternatively, the target element and the sensor may use any other suitable technology, such as optical technology.

[0095] Alternatively, as previously mentioned, in the examples shown, the first ring of the rolling bearing is the stationary outer ring 10 and the second ring is the rotating inner ring 12 .

[0096] As an alternative, the opposite configuration can be provided, with the first ring forming a fixed inner ring and the second ring forming a rotating outer ring. In this case, the groove 50 is formed on the axially inner cylindrical surface of the outer ring, the axially inner cylindrical surface of the outer ring forming the bore of said outer ring, and the sensor 24 is mounted on the inner ring.

[0097] In the example described, the rolling bearing is provided with three rows of rolling elements. As another option, the rolling bearing may include only one row of rolling elements, or two rows of rolling elements, or four or more rows of rolling elements. In the example shown, the rolling elements are rollers. The rolling bearing may include other types of rolling elements, such as balls. In another variant, the bearing may also be a sliding bearing without rolling elements.

Claims

1. A bearing comprising a first ring (10) and a second ring (12) which are rotatable concentrically relative to each other, characterized in that: At least one annular groove (50) is formed on the second ring (12) and is oriented toward the first ring (10), and the bearing further comprises: at least one target element (52) engaged in the groove (50) of the second ring and freely slidable in the circumferential direction in the groove, the target element (52) protruding into a hole (54) formed in the first ring (10), so that the first ring prevents the target element from rotating when the second ring rotates and the first ring is fixed, and at least one sensor (24) mounted on the first ring and facing the target element (52) to detect the axial position of the target element, The target element (52) is fixed in the axial direction relative to the second ring, an axial gap (56, 58) being provided between the target element (52) and the wall of the hole (54) of the first ring.

2. The bearing according to claim 1, characterized in that: The target element (52) is provided with a target (62) having a track encoded in an axial direction and facing the sensor (24).

3. The bearing according to claim 2, characterized in that: The target element (52) is also provided with a target holder (60) which engages in the groove (50) of the second ring and supports the target (62).

4. The bearing according to any one of claims 1 to 3, characterized in that The longitudinal axis (74) of the sensor is perpendicular to the axis (XX') of the bearing.

5. The bearing according to any one of claims 1 to 3, characterized in that The sensor (24) is disposed within the hole (54) of the first ring.

6. The bearing according to any one of claims 1 to 3, characterized in that The holes (54) of the first ring extend radially from an axial cylindrical surface (10a) of the first ring radially facing the second ring, and open on an opposite axial cylindrical surface (10b) radially located on the side opposite to the second ring.

7. The bearing according to any one of claims 1 to 3, characterized in that The sensor (24) contacts the target element (52) in a radial direction.

8. The bearing according to claim 7, characterized in that The bearing further comprises a prestressing element (66) arranged between the first ring (10) and the sensor (24) to maintain contact between the sensor and the target element (52).

9. The bearing according to any one of claims 1 to 3, characterized in that The bearing further comprises at least one row of rolling elements (18; 22) arranged between raceways (28, 26; 36, 34) provided on the first ring and the second ring.

10. The bearing according to any one of claims 1 to 3, characterized in that The bearing comprises at least one row of axial rolling elements (18) arranged between radial raceways (28, 26) provided on the first ring and the second ring and at least one row of radial rolling elements (22) arranged between axial raceways (36, 34) provided on the first ring and the second ring, the second ring (12) comprising a protruding nose (40), the protruding nose (40) engaging in the annular groove (38) of the first ring and protruding radially from the axial cylindrical surface (12b) of the second ring, the groove (50) being formed on the axial cylindrical surface (12b).

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