Patent Publication Number: US-2021178812-A1

Title: Wheel hub for mounting a vehicle wheel

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. National Phase of PCT Appln. No. PCT/DE2019/100387 filed Apr. 30, 2019, which claims priority to DE 10 2018 111 557.1 filed May 15, 2018 and DE 10 2018 111 841.4 filed May 17, 2018, the entire disclosures of which are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to a wheel hub for mounting a vehicle wheel on a wheel axle, having a hub body and a roller bearing unit for mounting the hub body on an axle journal of the wheel axle, wherein the roller bearing unit has annular roller bearings for engaging the axle journal, each of which has an outer ring, an inner ring, and a plurality of rolling elements. 
     BACKGROUND 
     The publication DE 10 2014 200 714 A1 describes a wheel hub for commercial vehicles (referred to there as commercial motor vehicles). 
     Various systems for autonomous driving are currently being developed for commercial vehicles such as trucks, trailers and buses. Remote control sensors such as radar, laser, ultrasound, camera, etc. are used to control these systems. In this context, an even higher demand for additional sensor data can be expected in the future. The wheel forces are of particular interest, but vibration and temperature should also be measured. 
     SUMMARY 
     It is desirable to provide a wheel hub which, with essentially the same structure, takes this increased need for sensor data into account. 
     A wheel hub for mounting a vehicle wheel on a wheel axle, includes a hub body and a roller bearing unit for mounting the hub body on an axle journal of the wheel axle, which has annular roller bearings for engaging the axle journal, which in turn each have an outer ring, an inner ring, and a plurality of rolling elements. The wheel hub also includes at least one measurement ring arranged to be axially adjacent to at least one of the inner rings for engaging around the axle journal, wherein this measurement ring has at least one measurement setup for measuring strain and/or compression. The measurement ring with the at least one measurement setup for strain and/or compression measurement is a type of sensor for determining wheel forces, which can be integrated particularly well into the wheel hub. The measurement ring makes it possible to measure the forces on the wheel bearing (contact forces, wheel and braking forces for disc brakes). Since the at least one measurement ring directly adjoins an inner ring of one of the roller bearings, the measurement ring can also be regarded as part of the roller bearing unit. 
     The measurement ring or at least one of the measurement rings may be arranged between the inner rings of the annular roller bearings. It connects directly axially to at least one of the inner rings. 
     Alternatively or additionally, the measurement ring or at least one of the measurement rings on a wheel side of the wheel hub may axially adjoin one of the inner rings. The wheel side is the side of the wheel hub on which the vehicle wheel can be mounted on the hub, and on which the vehicle wheel is essentially also located after installation. 
     Alternatively or additionally, the measurement ring or at least one of the measurement rings on a drive side of the wheel hub may axially adjoin one of the inner rings. The wheel side and the drive side are opposite sides of the wheel hub. The drive side of the wheel hub is the side from which the axle journal can be inserted into the wheel hub. 
     The measurement setup may also be a measurement setup for strain and/or compression measurement by means of strain gauges. Strain gauges are measurement devices for the detection of strain and compressive deformations. The electrical resistance thereof changes even with slight deformations and are used as strain sensors. As a rule, they are glued with special adhesive to components that deform minimally under load. This deformation (strain) then changes the resistance of the strain gauge. 
     The measurement setup may be a measurement setup for strain and/or compression measurement using Sensotect thin-film sensors, in which the functionality of the strain gauge is implemented as a direct coating on the respective component. 
     The measurement setup may be a measurement setup for measuring strain and/or compression using a magnetoelastic sensor. 
     The at least one measurement setup may be arranged on the surface, in particular the outer surface, of the measurement ring. 
     The at least one measurement setup may be arranged on or in an insert part integrated into the measurement ring. 
     A plurality of measurement setups may be provided, which are arranged on the measurement ring distributed over the circumference, in particular distributed uniformly over the circumference. In particular, four measurement setups are provided for measuring the strains at four widely distributed points (at 12 o&#39;clock, 3 o&#39;clock, 6 o&#39;clock, 9 o&#39;clock). Alternatively, two segments with corresponding measurement setups are provided. 
     The wheel hub, in particular the roller bearing unit of the wheel hub, may have a bushing for axially bracing the inner rings and the at least one measurement ring. The bushing is preferably arranged directly between the inner rings. 
     The annular roller bearings may be designed as tapered roller bearings. These are particularly suitable for constructing a wheel hub for commercial vehicles (commercial motor vehicles). The rolling elements of these tapered roller bearings are rollers in the form of a cone. The bearing unit is in particular an angular contact roller bearing. 
     A wheel hub as described above may be used for determining data about occurring wheel forces of a vehicle wheel during driving, in particular during autonomous driving, of the corresponding vehicle. This vehicle may be in particular a commercial vehicle (commercial motor vehicle), such as a trucks, trailer or bus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following, the wheel hub is explained by way of example with reference to the attached drawings using preferred exemplary embodiments, the features shown below being able to represent various aspects both individually and in combination. In the figures: 
         FIG. 1 : shows a wheel hub according to a first embodiment, 
         FIG. 2 : shows a roller bearing unit of a wheel hub according to a second embodiment, 
         FIG. 3 : shows a roller bearing unit of a wheel hub according to a third embodiment, 
         FIG. 4 : shows a roller bearing unit of a wheel hub according to a fourth embodiment, 
         FIG. 5 : shows two different arrangements of measurement setups on/in a measurement ring, and 
         FIG. 6 : shows the structure of a measurement ring with ring segments. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows the essential components of a wheel hub  10  for mounting a vehicle wheel on a wheel axle in half section (wheel and wheel axle not shown). The wheel hub  10  comprises a hub body  12 , i.e., the actual hub, and a roller bearing unit  14  for mounting the hub body  12  on an axle journal (not shown) of the wheel axle, which is represented by the imaginary axis of rotation A. Only one part of the hub body  12  near the axle is shown in  FIG. 1 . 
     The roller bearing unit  14  is constructed as a double row angular contact roller bearing and comprises two roller bearings  16 ,  18 , which in the example shown are designed as tapered roller bearings  20 ,  22  and are arranged in an O arrangement. Each of the roller bearings  16 ,  18  has an outer ring  24 , a plurality of rolling elements  26  and an inner ring  28 . The outer rings  24  of the roller bearings  16 ,  18  are fitted in the hub body  12  of the wheel hub  10 . The rolling elements  26  used in a rolling element cage are guided on the outside on the respective outer ring  24  and on the inside on the respective inner ring  28  and can roll thereon. The rolling elements  26  are designed as tapered rollers. An axial end of the wheel hub  10  is a drive-side end and the corresponding side is the drive side  30  of the wheel hub  10 . An axial end of the wheel hub  10  opposite the drive-side end is a wheel-side end and the corresponding side is the wheel side  32  of the wheel hub  10 . 
     A measurement ring  34  is arranged axially adjacent to one of the inner rings  28 . This measurement ring  34  forms a sensor for determining wheel forces via strain and compression measurements. In the example in  FIG. 1 , the measurement ring  34  on the drive side  30  of the wheel hub  10  connects axially to one of the inner rings  28  and forms the drive-side end of the wheel hub  10  at this radial height. The strain and compression measurements take place with regard to strains and compressions in the axial direction and/or radial direction and/or tangential direction and allow conclusions to be drawn about the corresponding axial, radial and tangential forces. 
     With installed tapered roller bearings  20 ,  22 , the outer rings  24  are supported at a distance referred to as the collar width, positioned in relation to one another on a respective shoulder within the hub body  12 . The axial bracing of the inner rings  28  (for example by means of an axle nut on the axle journal) results in a defined bearing play of the roller bearing unit  14 . The wheel hub  10  can then be mounted on an axle journal (also known as a steering knuckle). 
     The wheel hub  10  is intended for use in trucks, trailers, buses and other commercial vehicles (commercial motor vehicles). 
     External forces on the wheel hubs  10  during operation of the corresponding vehicle, such as contact forces (axial forces Fa, radial forces Fr) and tangential forces (Ft) when accelerating or braking, cause strains on the inner rings  28  and on the mounted measurement rings  34 . 
     Since the bearing is designed as a tapered roller bearing in an O arrangement, it must be braced axially, for example between an axle nut and the axle shoulder. The inner rings  28  can directly abut, as shown here in  FIG. 1 . 
       FIGS. 2 to 4  show design variants of the wheel hub  10 . Since the corresponding wheel hubs  10  have essentially the same structure as the wheel hub  10  shown in  FIG. 1 , only the differences will be discussed here. 
       FIG. 2  shows a structure in which the measurement ring  34  is arranged between the axle journal and the inner ring  28  of the drive-side roller bearing  18 , i.e., on the drive side  30 . In this design variant, the inner rings  28  are braced via a bushing  36 . 
       FIG. 3  shows a structure in which the measurement ring  34  is designed as a bushing and is arranged between the inner rings  28 . In other words, the inner rings  28  are braced over the measurement ring  34  designed as a bushing. 
       FIG. 4  shows a structure in which the measurement ring  34  is arranged on the wheel side  32 . In this design variant, the inner rings  28  abut directly, i.e., immediately. 
       FIGS. 5 and 6  show details of the different embodiments of the measurement ring  34 . 
       FIG. 5  shows two measurement rings  34 . In the case of the left-hand measurement ring  34 , the strains/compressions are measured directly on the surface  40  of the measurement ring  34  via a measurement setup  38 . In the example, the measurement setup  38  is a setup with strain gauges or Sensotect sensors attached to the surface  40 . In the case of the right-hand measurement ring  34 , the strain is measured in/on additional elements  42  (only one of which is shown) which are introduced into the measurement ring  34 . 
       FIG. 6  shows a measurement ring  34 , which has a holding ring  44  as a base with four (n=4) circumferentially distributed holding elements  46 , between which four (n=4) ring segments  48  are arranged on the outside of the measurement ring  34 . The strains/compressions are measured on these ring segments  48 . 
     The various embodiments may share some common features: 
     The strains/compressions are measured via strain gauges or corresponding sensors for strain measurement (e.g., from Sensotect) on an additional ring, the measurement ring  34 . It is provided to measure the strains at n points (e.g., n=4 at 12 o&#39;clock, 3 o&#39;clock, 6 o&#39;clock, 9 o&#39;clock). Two bonded strain gauges or Sensotect strain gauges (one measures in the axial direction, the second in the tangential direction) are connected at each measuring point for temperature compensation. This is done in a half-bridge connection. Alternatively, the measuring points can also be differently interconnected (e.g., full bridge) and more or fewer measuring points could be provided (at least two for the separation of contact and tangential forces). 
     The measurement rings  34  are arranged on the wheel side  32 , on the drive side  30 , or between the inner rings  28 . 
     The wheel forces are calculated from the measured strains/compressions. 
     LIST OF REFERENCE SYMBOLS 
     
         
           10  Wheel hub 
           12  Hub body 
           14  Roller bearing unit 
           16  First roller bearing, annular 
           18  Second roller bearing, annular 
           20  First tapered roller bearing 
           22  Second tapered roller bearing 
           24  Outer ring 
           26  Rolling element 
           28  Inner ring 
           30  Drive side 
           32  Wheel side 
           34  Measurement ring 
           36  Bushing 
           38  Measurement setup 
           40  Surface 
           42  Insert part 
           44  Holding ring 
           46  Holding element 
           48  Ring segment