The invention relates to a mechanical system com- prising at least two parts, where these two parts are moveable relative to each other, and more specifically does the invention relate to mechanical systems that are equipped with devices that monitor parameters relating to the performance of the mechanical system or adjacent sys- tems.

With increasing complexity of mechanical systems, or of systems where mechanical systems form a subsystem, the cost of these systems, or the cost to operate such systems also increases. This puts higher demands on the operating reliability of such systems as well as demands on the need to control the operation of such systems or the need to detect possible malfunctioning in an as early stage as possible.

Therefore there is a growing tendency to equip systems with measuring, monitoring and control devices, to measure parameters that e. g. relate to the performance of the system in question or of the surrounding parts, and monitor such parameters, to be able to take action when e. g. a malfunction occurs at e certain place. Such action can be to actuate a control device or give a warning to an operator for instance.

* Whenever the system comprises moving parts, e. g. rotating parts or parts with linear movement, the measure- ment and control becomes more difficult, notably where measurements are taken, or control is executed in the mov- ing part.

Today speed monitoring can be found in wheels of cars, trucks and railway coaches to detect blocking of wheels during braking, known as ABS. Detecting of speed differences plays also a role in traction control systems.

Temperature sensors have been used in railways, notably in high speed applications and e. g. in paper mak-

ing machines.

In the US trucks have been equipped with means to detect loss of lubricant.

Certain cars, mainly in the luxury segment, have been equipped with sensors for measuring tire pressure, or in less sophisticated executions, sensors that measure a sudden change in tire pressure usually indicating a punc- ture.

Position sensors are gaining use in printing ma- chines.

However this type of monitoring on or near moving parts is difficult, and consequently costly and has there- fore so far been limited to single or a few parameters.

Also in many cases is the sensor positioned on a station- ary part and thus limiting its usefulness. More complex monitoring has so far not been possible. E. g. to reliably determine loads has been very cumbersome, if at all possi- ble.

It is an object of the present invention to pro- vide a mechanical system comprising moveable parts, that includes monitoring and control of a broad selection of functions of the system or of adjacent systems.

The object is reached with a mechanical system according to claim 1. With such a system according to the invention it is possible to transfer data to and from the rotating part. This data may be originating from different sources. The data is transferred by the power and data coupling device without contact. Such a device usually comprises two parallel rings or ring segments. The rings can be parallel in the axial direction or in the radial direction, or in ac combined axial radial direction.

This means that the construction can easily be made to function reliably and to be accessible for signals from different sensors. Consequently different sensors can be housed on the moving part of the system. It is also clear that when the system comprises more than two parts, and e. g. the first part is stationary and the second part moves relative to the first part and a third part moves

relative to the second part, then a signal from a sensor on the third part, can be transferred by a first data cou- pler to the second part. That signal can then by means of a second data coupler be transferred to the first, sta- tionary part. It will be clear that also in the case de- scribed above, signals from more than one sensor can re- liably be handled.

It is possible to use a variety of types of power and data coupling devices. They may be of inductive, ca- pacitive, of radiographic or any other non-contacting type.

In certain embodiments of the invention the sys- tem may comprise control means. The control signals can be fed to the corresponding actuators via the power and data coupling device. It can also be conceived that the same power and data coupling device transferred the measured signals that were the cause of the control signals to be sent, thus forming a closed control loop.

Also in certain embodiments of the invention it may be necessary that the sensors and/or actuators in- volved need energy for their operation. Such energy may in these embodiments be transferred from a source of electri- cal energy that is located at, or connected to a station- ary part of the system, to the moving part where the sen- sor and/or actuator is located.

In certain embodiments of the invention the power and data coupling device may be connected to a central processing unit. The data can then be manipulated, treated, stored, and/or further evaluated. Also is it pos- sible that the processing unit generates control signals to the control means and the corresponding actuators.

In many embodiments of the mechanical system ac- cording to the invention are the two parts connected to each other by means of a bearing or bearing systems. This bearing can be any type of bearing, such as a ball bear- ing, an angular contact ball bearing, a taper roller bear- ing, a cilindrical roller bearing, a spherical roller bearing, a plain bearing or any other type of bearing.

Also can the bearing system comprise a multitude of these bearings in any combination. The bearing or the bearing system can be with rotating inner ring or with rotating outer ring.

A special embodiment where the invention can be used with advantage is a wheel end system of a vehicle.

The vehicle can be a truck, a car, a coach or any other vehicle. The wheel end system may comprise shaft or drive shaft, support bearing (s), wheel, mechanical or electrical drive means, steering knuckle, king pin, suspension, brake system, steering system, power steering, tire pressure control, etc.

Such systems can then be fitted with load sensors for measuring wheel load, brake load, bearing preload, king pin load, steering angle, brake temperature, tire pressure, presence of lubricant etc.

Other mechanical systems according to the inven- tion can be used with advantage in robots, rolling mills, machine tools, paper, making machines, printing machines, etc, for measuring loads, speeds, angular displacements, linear displacements, temperatures and the like.

Although many examples relate to mechanical sys- tems where the parts exhibit relative rotational movement, but the invention equally relates to systems where there is relative linear movement.

The invention will further be explained with the description of certain preferred embodiments of the inven- tion, illustrated by the drawings that show in: Fig. 1 a view in section of a wheel hub unit for cars equipped with a power and data coupling device, Fig. 2 a view in section of a front wheel hub unit for trucks, equipped with a power and data coupling device and with sensors for load and tire pressure and with connections for. a king pin, Fig. 3 a view in section of a similar type of wheel hub unit as in fig. 2, but with a different design, Fig. 4 a view in section of a rear wheel hub unit for driven or non-driven wheels for trucks or trailers,

equipped with a power and data coupling device and sen- sors, Fig. 5 a view similar to fig. 4, but with a drive shaft present, and Fig. 6 a view in section of a wheel end module.

In the figures elements with the same or with similar functions are indicated with the same reference numbers.

Referring to fig. 1, a wheel hub unit for cars is shown, with in this embodiment two rotating parts 1 and 2, a non-rotating part 3, connected by two ball sets 4. The rotating parts 1 and 2 comprise inner races for the balls 4 and the non-rotating part 3 comprises outer races, to- gether forming two angular contact ball bearings with dif- ferent pitch diameters. Equal pitch diameters are also possible. Rotating part 1 comprises bolt holes 5 for re- ceiving bolts with which the car wheel can be attached to the wheel hub unit. The non-rotating part 3 comprises bolt holes 6 for receiving bolts with which the wheel hub unit can be attached to the suspension. Rotating part 1 also comprises splines 7 for receiving a drive shaft with con- forming splines and through which torque is transmitted from the drive shaft to the wheel. The unit carries vari- ous sensors, such as load sensors and temperature sensors, of which only sensor 21 is shown in fig. 1, both on the rotating parts as on, the non-rotating part. Sensor 21 in fig. 1 is a load sensor. Sensors positioned somewhere else e. g. in the suspension can also be linked, to monitor e. g. the angular displacement of the kingpin (steering angle).

Sensors that are positioned on the rotating parts 1,2 (or on the wheel itself) do transfer their signals via a power and data coupler device 8,9, from the rotating parts 1,2 to the non-rotating part 3, from where the signals can easily be transferred to a central processing unit for evaluation, processing and storing. Where necessary the sensors receive their power from the non-rotating part and this power is also transferred via the power and data cou- pler device. This transfer of power through the power and

data coupler device takes place in the opposite direction as the transfer of data, mentioned above.

The power and data coupler device comprises two parallel rings (or ring segments) 8,9 of which one ring 8 is rotating and the other ring 9 is non-rotating. The par- allel rings can be axially or radially positioned or a combination of these.

Figs 2 and 3 show two different designs of a front wheel unit for trucks. Fig. 2 shows a system with a bearing with a rotating outer ring 1, whereas fig. 3 shows a system with bearing with a rotating inner ring 1. The unit comprises rotating parts 1,2 and 10. Rotating part 1 and non-rotating part 3 comprises raceways for rolling elements 4. Elements 1,3 and 4 together form a double row taper roller bearing. Connected to rotating part 1 by means of bolts are rotating parts 2 and 10, respectively for receiving the wheel, connected by means of bolts 5 (only one bolt indicated with the numeral) and the brake disk. Sensor 21 in the embodiment of fig. 2 measures load and sensor 21 in the embodiment of the invention of fig. 3 measures temperature and speed. The signals measured by sensor 21 are transferred via the power and data coupling device to the stationary part. Sensor 22 in fig. 3 is a load sensor, and is part of the non-rotating part already.

Therefore the signal of sensor 22 is not transferred via the power and data coupling device. The non-rotating part 3 is connected by means of an interference fit to part 11.

Part 11 comprises bolt holes 6 for receiving bolts for connection to the suspension. Part 11 also comprises ele- ments 12 for holding the king pin of a steering arrange- ment.

Referring to fig. 2, in a recess in rotating part 1 a load sensor 21 is position such that is placed in the load carrying area of the double row taper roller bearing.

This sensor 21 is connected to the rotating part 8 of a power and data coupling device 8,9. The non rotating part 9 of the power and data coupling device is connected to stationary part 6 and the rotating part 8 of the power and

data coupling device 8,9 is connected to rotating part 1.

Parts 8 and 9 of the power and data coupler device are parallel rings (or ring sections).

The wheel hub unit also comprises air pressure sensor 15. Sensor 15 it self is non-rotating and its sig- nal output may thus be connected to the non-rotating part 9 of the power and data coupler device 8,9. Sensor 15 measures the air pressure in the wheel tire. The air pres- sure is brought to the sensor via ducts 13 and 14. Rotat- ing duct 13 is connected to non-rotating duct 14 by means of sealed bearing, e. g. a deep groove ball bearing 16.

In figs. 2 and 3 brake disks 10 are shown. In fig. 2 it concerns a fixed brake disk and in fig. 3 two floating disks are shown.

Figs. 4 and 5 show a view in section of a rear wheel hub unit for non-driven (fig. 4) and driven (fig. 5) wheels for trucks or trailers, respectively without and with a drive shaft 17, both equipped with sensors 21,22 and a power and data couple device 8,9. The arrangement is similar to the one described above and shown in fig. 3.

Fig. 6 shows a view in section of a wheel end module comprising rotating parts 1,2 and 10 and non- rotating parts 3 and 11. The module comprises a power and data coupling device 8,9 for transfer of data from sensors connected to the rotating parts of the module. In fig. 6 such sensors are not shown. Load sensor 22 and air pres- sure sensor 15 in fig. 6 are connected to the non-rotating part already and thus need not to pass the power and data coupling device 8, 9. The wheel end module of fig. 6 shows bolts 5 for connecting the wheel, bolt holes 6 for receiv- ing the bolts with which the module can be mounted to the suspension, and the unit also comprises brake disks 10.