Wheel bearing unit for supporting a vehicle wheel, having a measuring device, and method for installing a measuring device

Abstract

The invention relates to a wheel bearing unit for supporting a vehicle wheel, having a wheel hub and a rolling bearing unit, wherein the rolling body unit comprises at least two rows of rolling bodies which are arranged between an outer ring (1) and the wheel hub or an inner ring, wherein a measuring device (2) having at least one measuring point (5) is provided on the outer ring (1), and wherein the measuring device (2) is frictionally connected to the outer ring (1), in particular by being pressed thereon or thermally shrunk thereon.

Description

[0001]Wheel bearing unit for supporting a vehicle wheel with a measuring device and method for assembling a measuring device 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 and the wheel hub or an inner ring, wherein 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. Various systems for autonomous driving are currently being developed for commercial vehicles such as trucks, trailers and buses. Remote sensors such as radar, laser, ultrasound, camera, etc. are essentially used to control these systems, in particular for so-called "steer-by-wire" systems. In the future, an even greater demand for additional sensor data is to be expected in this context.The wheel forces are of particular interest, but vibration and temperature should also be measured. Particularly with regard to autonomous driving, it will be necessary to determine the forces acting on the wheel bearing as close and precisely as possible to the vehicle's wheel. State-of-the-art solutions exist in which the necessary measuring devices are applied directly to the wheel bearing by means of coating or bonding. However, the associated cost increase reduces market acceptance. Alternative solutions propose 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. Due to their layout and design, the systems known in the state of the art cannot currently provide very precise data or are extremely expensive.The document DE 102018111841 A1 describes a wheel hub for supporting a vehicle wheel on a wheel axle, wherein a measuring ring is provided for measuring forces on the wheel bearing. This measuring ring is attached axially in front of an inner ring and has at least one measuring structure for measuring strain and / or compression. The object of the invention is to create a wheel bearing unit that enables the wheel forces on the wheel to be measured as accurately and cost-effectively as possible. This 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.The wheel bearing unit according to the invention for supporting a vehicle wheel has 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 thermally shrinking. 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 the measuring device cannot be completely separated from the outer ring without causing damage. The measuring device is preferably applied to the outer circumferential surface of the outer ring.According to one embodiment, the measuring device is designed as an annular disk which has at least two radially projecting bearing surfaces towards 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 bearing surfaces. The measuring device is preferably divided into sectors, in particular three to four sectors. This means that the measuring device has separable regions in the circumferential direction in which, for example, measuring points can be arranged. The measuring device preferably has a plurality of measuring points. The measuring points can be distributed around the circumference of the annular disk of the measuring device at uniform or irregular intervals. The measuring point can be, for example, a coating, e.g. 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 part, to the outer surface of the measuring device. 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. The measuring device is particularly preferably sealed.The seal is applied to the measuring device in particular to protect the measuring points. According to one embodiment, the measuring device has a further measuring point that measures the temperature and / or the acceleration. The invention further relates to a method for mounting a measuring device on a wheel bearing unit, wherein in a first step a lateral 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 position-oriented and force-fitting manner, and in a subsequent step the measuring point of the measuring device is sealed. During production of the measuring device, the annular surface of the disc is first exposed. After the measuring points have been applied, the exposed, annular surface is completely sealed using a substrate, so that a full-surface annular surface is created. This serves to protect the measuring points.The measuring device is also connected to electronics which converts the measurement signals into vehicle-typical force values ​​and feeds them into the vehicle ECU. The invention is explained below by way of example with reference to the attached drawings using preferred exemplary 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 Figure 3 Figure 1 shows an outer ring 1 of a wheel bearing unit in a three-dimensional view. The outer ring 1 has fastening points 1a which serve to fasten 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. Between the two radial legs 2a, the measuring device 2 has a substantially cylindrical surface 2b on which measuring points 5 can be applied. The annular disk of the measuring device 2 is provided with at least one, preferably 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 on the measuring device 2, distributed over the circumference. As can also be seen in Figure 1, the cylindrical surface 2b of the measuring device 2 is divided into sectors 4 over its circumference.Particularly preferably, the surface 2b has at least three sectors. In particular, one measuring point 5 is applied to each sector 4. Figure 2 shows a sectional view of the outer ring 1 with the measuring device 2 from Figure 1. It can be seen that the measuring device 2 is applied to the outer surface of the outer ring 1 in a force-fitting manner. Figure 3 shows an outer ring 1 with a measuring device 2, in which a sealing 7 of the measuring points 5 has already taken place. The sealing 7 of the measuring points 5 serves to protect them and thus to 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. Figure 4 shows a sectional view of the outer ring 1 according to Figure 3.The measuring device 2 has contact surfaces 3 that create an annular contact surface for the outer ring 1. The contact surfaces 3 negate minor unevenness on the surface of the outer ring 1. Secure attachment of the measuring device 2 is ensured. 1 Outer ring 1a Attachment points 2 Measuring device 2a Radial legs 2b Cylindrical surface 3 Contact surface 4 Sectors 5 Measuring point 6 Additional measuring point 7 Sealing 7a Guide A Axial direction R Radial direction.

Claims

Patent 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 in that the measuring device (2) is non-positively connected to the outer ring (1), in particular by pressing or thermally shrinking.

2. Wheel bearing unit according to claim 1, characterized in 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 in 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 in that the measuring device (2) has a plurality of measuring points (5).

5. Wheel bearing unit according to one of the preceding claims, characterized in 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 in 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 in that the measuring device (2) has a seal (7).

8. Wheel bearing unit according to one of claims 5 to 7, characterized in 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 position-oriented and force-fitting manner, and in a following step the measuring point (5) is sealed.

Images