Wheel bearing unit for supporting a vehicle wheel with a measuring device and method for mounting a measuring device

Abstract

The invention relates to a wheel bearing unit for supporting a vehicle wheel, with a wheel hub and a rolling bearing unit, wherein the rolling element unit comprises at least two rows of rolling elements which are provided between an outer ring (1) and the wheel hub or an inner ring, wherein a measuring device (2) with at least one measuring point (5) is provided on the outer ring (1), and wherein the measuring device (2) is non-positively connected to the outer ring (1), in particular by pressing or thermal shrinking.

Description

[0001] The invention relates to a wheel bearing unit for supporting a vehicle wheel, comprising a wheel hub and a rolling bearing unit. The rolling element unit comprises at least two rows of rolling elements arranged between an outer ring and the wheel hub or an inner ring. A measuring device with at least one measuring point is provided on the outer ring. Furthermore, the invention relates to a method for assembling this measuring device.

[0002] Various autonomous driving systems are currently being developed for commercial vehicles such as trucks, trailers, and buses. These systems, especially so-called "steer-by-wire" systems, are primarily controlled by remote sensors such as radar, laser, ultrasound, cameras, etc. In the future, an even greater demand for additional sensor data is expected in this context. Wheel forces are of particular interest, but vibration and temperature will also be measured.

[0003] Especially with regard to autonomous driving, it is necessary to determine the forces acting on the wheel bearing as close and precisely as possible to the vehicle's wheel.

[0004] For example, state-of-the-art solutions involve applying the necessary measuring devices directly to the wheel bearing using a coating or adhesive. However, the associated cost increase is reducing market acceptance. Alternative solutions suggest attaching the measuring device to the wheel bearing using screws. This weakens the bearing structure at these points to such an extent that material fatigue can be expected at these attachment points.

[0005] Due to their arrangement and design, the systems known in the state of the art cannot currently provide very accurate data or are extremely expensive.

[0006] The publication DE 10 2018 111 841 A1 describes a wheel hub for supporting a vehicle wheel on a wheel axle, with a measuring ring provided for measuring forces on the wheel bearing. This measuring ring is mounted axially in front of an inner ring and has at least one measuring setup for strain and / or compression measurement.

[0007] The object of the invention is to create a wheel bearing unit which enables the wheel forces on the wheel to be measured as accurately and cost-effectively as possible.

[0008] The object is achieved according to the invention by a wheel bearing unit having the features of claim 1 and a method for assembling the wheel bearing unit according to claim 9. Preferred embodiments of the invention emerge from the subclaims and the following description, which can each represent an aspect of the invention individually or in combination.

[0009] The wheel bearing unit according to the invention for supporting a vehicle wheel comprises a wheel hub and a rolling bearing unit, wherein the rolling element unit comprises at least two rows of rolling elements provided between an outer ring and the wheel hub or an inner ring. A measuring device with at least one measuring point is provided on the outer ring, wherein the measuring device is non-positively connected to the outer ring, in particular by pressing or thermal shrinking.

[0010] This creates a cost-effective solution that also ensures accurate measurement data delivery. Preferably, the measuring device is connected to the outer ring of the wheel bearing in such a way that it cannot be completely separated from the outer ring without causing damage. The measuring device is preferably mounted on the outer surface of the outer ring.

[0011] According to one embodiment, the measuring device is designed as an annular disc having at least two radially projecting contact surfaces with the outer ring. Thus, the measuring device does not rest against the outer ring with its entire inner surface, but only via the surfaces of the radially projecting contact surfaces.

[0012] Preferably, the measuring device is divided into sectors, in particular three to four sectors. This means that the measuring device has separable areas in the circumferential direction in which, for example, measuring points can be arranged.

[0013] The measuring device preferably has a plurality of measuring points. The measuring points can be distributed at even or irregular intervals around the circumference of the annular disk of the measuring device. The measuring point can be a coating, such as a Sensotect coating. With this thin-film sensor technology, the functionality of the strain gauges is realized as a direct coating on the respective component. This coating is applied, at least in some areas, to the outer surface of the measuring device.

[0014] Alternatively, the measuring point can also be a strain gauge applied to the outer surface of the measuring device. Strain gauges are measuring devices for detecting stretching and compressive deformations. They change their electrical resistance even with small deformations and are used as strain sensors. They are usually bonded with special adhesive to components that deform minimally under load. This deformation (strain) then leads to a change in the resistance of the strain gauge. These solutions guarantee very precise measurement data on the prevailing forces on the wheel bearing.

[0015] Particularly preferably, the measuring device has a seal. The seal is applied to the measuring device, in particular, to protect the measuring points.

[0016] According to one embodiment, the measuring device has a further measuring point which measures the temperature and / or the acceleration.

[0017] The invention further relates to a method for mounting a measuring device on a wheel bearing unit, wherein in a first step a circumferential surface of the outer ring is treated, in particular finely turned, and in a further step the measuring device is connected to the outer ring in a positionally oriented and force-fitting manner, and in a subsequent step the measuring point of the measuring device is sealed.

[0018] During the manufacturing of the measuring device, the annular surface of the disc is first exposed. After the measuring points are applied, the exposed annular surface is completely sealed with a substrate, creating a full-surface annular surface. This serves to protect the measuring points. The measuring device is also connected to electronics that converts the measurement signals into vehicle-specific force values and feeds them into the vehicle's ECU.

[0019] The invention will be explained below by way of example with reference to the accompanying drawings using preferred embodiments, wherein the features presented below can represent an aspect of the invention both individually and in combination. They show: Fig. 1 an outer ring with a measuring device according to the invention in a three-dimensional view Fig. 2 a sectional view of a measuring device according to the invention Fig. 3 an outer ring with a sealed measuring device in a three-dimensional view Fig. 4 a sectional view of the outer ring according to Fig. 3

[0020] Fig. 1 shows an outer ring 1 of a wheel bearing unit in a three-dimensional view. The outer ring 1 has attachment points 1a, which serve to attach the wheel bearing to a wheel carrier. The outer ring 1 also has a substantially cylindrical outer surface on which a measuring device 2 is arranged. The measuring device 2 is designed as a substantially ring-shaped disk. A radially outwardly projecting, circumferential leg 2a is formed on each end face of the measuring device 2. The measuring device 2 has a substantially cylindrical surface 2b between the two radial legs 2a, on which measuring points 5 can be applied. The annular disk of the measuring device 2 is provided with at least one, preferably with several, measuring points 5. The measuring points 5 can be a coating, such as a Sensotect coating, or strain gauges.The measuring points 5 are provided distributed over the circumference of the measuring device 2. As shown in . Fig. 1, the cylindrical surface 2b of the measuring device 2 is divided into sectors 4 over its circumference. It is particularly preferred that the surface 2b has at least three sectors. In particular, one measuring point 5 is applied to each sector 4. Fig. 2 is the outer ring 1 with measuring device 2 made of Fig. 1 is shown in a sectional view. It can be seen that the measuring device 2 is force-fitted to the outer surface of the outer ring 1.

[0021] Fig. Figure 3 shows an outer ring 1 with a measuring device 2, in which a sealing 7 of the measuring points 5 has already been applied. The sealing 7 of the measuring points 5 serves to protect them and thus ensure the longevity of the wheel bearing. The sealing 7 can, for example, have additional functions, such as a guide 7a, in particular a cable guide. The sealing 7 is preferably flush with the radial legs 2a of the measuring device 2.

[0022] Fig. 4 shows a sectional view of the outer ring 1 according to Fig. 3. The measuring device 2 has contact surfaces 3 that create an annular contact surface with the outer ring 1. The contact surfaces 3 minimize minor unevenness on the outer surface of the outer ring 1. This ensures secure attachment of the measuring device 2. List of reference symbols 1 outer ring 1a Attachment points 2 measuring device 2a Radial limbs 2b Cylindrical surface 3 Support surface 4 sectors 5 measuring point 6 Additional measuring point 7 Sealing 7a guided tour A Axial direction R Radial direction QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 111 841 A1

[0006]

Claims

[1] Wheel bearing unit for supporting a vehicle wheel, with a wheel hub and a rolling bearing unit, wherein the rolling element unit comprises at least two rows of rolling elements which are provided between an outer ring (1) and the wheel hub or an inner ring, wherein a measuring device (2) with at least one measuring point (5) is provided on the outer ring (1), characterized by that the measuring device (2) is non-positively connected to the outer ring (1), in particular by pressing or thermal shrinking. [2] Wheel bearing unit according to claim 1, characterized by that the measuring device (2) is designed as an annular disc which has at least two radially projecting bearing surfaces (3) towards the outer ring (1). [3] Wheel bearing unit according to claim 1 or 2, characterized by that the measuring device (2) is divided into sectors (4), in particular into three sectors (4). [4] Wheel bearing unit according to one of the preceding claims, characterized bythat the measuring device (2) has a plurality of measuring points (5). [5] Wheel bearing unit according to one of the preceding claims, characterized by that the at least one measuring point (5) is formed from a coating, in particular a Sensotect coating. [6] Wheel bearing unit according to one of the preceding claims, characterized by that the at least one measuring point (5) is formed from a strain gauge. [7] Wheel bearing unit according to one of the preceding claims, characterized by that the measuring device (2) has a seal (7). [8] Wheel bearing unit according to one of claims 5 to 7, characterized by that the measuring device (2) has a further measuring point (6) which measures the temperature or the acceleration. [9] Method for mounting a measuring device (2) on a wheel bearing unit according to one of the preceding claims, wherein in a first step a circumferential surface of the outer ring (1) is treated, in particular finely turned, and in a further step the measuring device (2) is connected to the outer ring (1) in a positionally oriented and force-fitting manner, and in a following step the measuring point (5) is sealed.

Images