The invention refers to a brake roller, a roller conveyor and a method of installation of a roller conveyor.

EP 2 922 775 B1 discloses a brake roller. A roller tube is rotatably supported about an axis in a stationary bearing. An eddy current brake with a tubular eddy current receiver is located within the roller tube and fixedly connected thereto. A magnet is stationarily connected with the bearing. When the roller tube rotates, an eddy currents is induced in the insert by the magnetic field, which counteracts the rotary motion of the roller shell with a braking torque that increases with increasing speed. Without any rotation, no brake torque is generated so that said brake roller is not suitable as a holding brake.

AT 516925 A1 shows a combined motorized and brake roller. The brake roller is operated by method comprising the steps: providing a command to start up the conveying roller, applying, on the basis of said command, electric voltage to the drive motor, and fully releasing or raising the brake only after a time delay. The releasing of the brake is thereby directly linked to the command for actuating This method requires a control interface linking the brake roller to a control that controls operation of the motor roller.

DE 197 31 310 A1 discloses a gravity roller conveyor with brake rollers for conveyed goods. Conveyed goods are entered in a respective section of the gravity roller conveyor and are braked by the brake rollers. The roller conveyor has a timer which has the task of releasing the brake after a certain preset time.

US 2014/0291118 A1 discloses a brake unit for an accumulating conveyor for braking at least one roller which is provided for transporting a unit load on a roller path of the accumulating conveyor by means of an endless traction mechanism. The brake unit is driven continuously during operation via an endless drive traction mechanism on a driving roll er and is configured, in an engaged operating state, for transmitting the rotational movement of the driving roller about an axis to a driven roller and, in a braking operating state, for slowing down the driven roller on a housing of the brake unit. The driven roller being connected to the roller via the endless traction mechanism.

US 2,979,177 A shows another gravity roller lane, having a brake shoe. The brake show is movable toward and away from a braking position.lt is the object of the present invention to provide means to avoid damages to the objects to be conveyed on a inclined roller track in case of a loss of a main power supply voltage. The invention is solved by the matter of the independent claims; embodiments are subject of the subclaims and the description.

The invention provides an easy possibility to hold the objects on a roller conveyor at the current position in case of a loss of a main power supply voltage.

The invention can universally be applied to any roller conveyors of any manufacturer and do not need any specific interfaces to a conveyor control.

In particular the brake roller does not comprise a motor to drive the brake roller or any other rollers and/or wherein the brake roller is not a motor roller. This refers to the isolated brake roller and/or to the roller conveyor.

As an example, In a roller conveyor, the brake roller is designed separately from a motor roller. Since the brake is actively held in an the freewheel state it generates waste heat, the waste heat does not accumulate within the already warm motor roller.

There is also an automatism provided to bring the brake roller back into the free wheel state as soon as the main power supply voltage is available again.

In particular the operation of the brake roller is completely independent from any commands or operation of the motor roller. Therefore a particular advantage of the inventive roller conveyor is that no control interface is required for exchanging information between the motorized roller and the brake roller. During insThe brake roller can easily be connected to the main power supply and is immediately ready for operation. For improving the functionality during restart of the conveyor, a time delay can be provided. The time delay is preset with the delayer and there is also no connection required fron the brake roller to the motor roller or any motor controlling units. An example embodiment of the invention is described with respect to the figures; herein show fig. 1 an inventive roller conveyor in perspective view; fig. 2 a detail of the roller conveyor according to figure 1 in perspective view; fig. 3 a functional diagram of the roller conveyor according to figure 1 ; fig. 4 the brake roller of the roller conveyor according to figure 1 in a schematic cross- sectional view; fig. 5 a diagram showing the relation between the main power supply voltage and the brake power voltage; fig. 6 a diagram showing the relation between the main power supply voltage and the brake power voltage in the state when main power supply voltage is available again.

Figure 1 shows an inventive roller conveyor 1. The roller conveyor 1 comprises a plurality of rollers 2,3,4, which are parallel arranged in a manner to provide a conveying tracking along a conveying direction D. The conveying rollers are mounted on a supporting frame 10.

The rollers 2, 3, 4 are arranged in a manner so as to provide an inclined conveying direction D. That means that the conveying direction D is an uphill and/or a downhill direction in relation to the horizontal plane.

In the roller conveyor 1 several drive segments 11 are provided. Each drive segment 11 comprises a plurality of rollers 2, 3, 4, which are connected to each other via a drive connection 21 (figure 2), so that the rotational movement of all rollers of one segment are coupled to each other. The drive connection may comprise one of more Poly-V-belts. The drive connection may be subject to slippage.

The segment 11 comprises a motor 2, a brake roller 4 and optionally one of more idler rollers 3. In the present embdiment the motor is a motor roller 2, where in an alternative embodiment the motor is separate to any rollers.

Reference is made to figure 3. Each of the rollers comprise a roller tube 22, 42, which are rotatably supported on at least one axle element 23, 43 by means of a non-shown bearing. Same applies to the idler rollers which are not shown in figure 3.

The motor roller 2 comprises a motor 24 for providing a drive force for the roller tube 22. Between the motor 24 and the roller tube 22 a coupler 25 is provided which provides a torqueproofconnection between a motor shaft of the motor 24 and the roller tube 22.

The motor 24 is connected via a motor power line 27 to a main power supply 14. The main power supply 14 provides a main power supply voltage V1 which is essential for the operation of the motor.

The function of the motor 24 is optionally controlled by a motor controller 26. The motor controller 26 may be located within the roller tube 22 (as shown in figure 3) or externally. The motor controller 26 may be connected by a motor control line 28 and/or optionally by external control line 12 to a conveyor controller 13.

In case of a loss of the main power supply voltage V1 in the main power supply 14, the motor roller 2 is not provided with electric energy. Any objects 9 located on the inclined drive track are exposed to the arbitrariness of gravity. Depending on the height difference and the mass of the objects 9, the objects 9 can be damaged when the objects 9 meet each other at the lower parts of the inclined track.

The loss of main power supply voltage may happen intentionally by pressing an emergency stop button 15 or unintentionally due to a power failure in the public power network or a by triggering a fuse.

Said loss of main power supply voltage comprises also a reduction of the main power supply voltage below a certain threshold value. An an example the main power supply merely provides a voltage of 5V instead of the regular 48V, which is also considered a s a loss of main power supply voltage, since the motor rollers cannot be operated properly anymore so that said risk of damage to the objects in given as described above.

For avoiding damages to the objects 9 in case of a loss of the main power supply voltage V1 , each segment 11 is provided with said brake roller 4. During normal use of the conveyor 1 the brake roller 4 is in a free wheel state. In the free wheel state the brake roller 4 is operating similar to an idler roller 3 and does not provide a brake force (regular friction is not considered as brake force).

The brake roller 4 is adapted to be automatically and immediately transferred into a brake state in case that the main power supply voltage V1 is not present anymore to provide the motor rollers 2 with sufficient power (loss of main power supply voltage).

The brake roller 4 has a brake 44 (figure 3) which can selectively provide a brake force to the roller tube 42. On the one side the brake 44 is fixedly connected to one of the non-rotating axle elements 43, on the other side the brake 44 is connected to the roller tube 42 in particular via a coupling 45. An exemplary coupling 45 is disclosed in WO 2018/109165 A1. The brake 44 is connected to the main power supply 14 by means of a brake power line 47.

Figure 4 shows the brake 44 in more detail. The brake 44 has a first brake element 441 located fixed within the roller tube 42 and a second brake element 442 fixedly connected to the roller tube 42. The first and the second brake elements 441 , 442 can be selectively brought into engagement with each other, e.g. by frictional or positive engagement.

The brake is in particular a holding brake which should - in the brake state - provide a brake force also in case of no rotation. Consequently an inductive brake (e.g. disclosed in EP 2 922 775 B1), where the brake force is merely based on a relative movement of magnetic components within the brake roller is of minor suitability for the present function. A brake spring 444 or any other power storage urges the first and the second brake elements 441 , 442 with a second force F2 against each other. A brake actuator 443 provides a first force F1 counteracting the second force F2, keeping the brake in the free wheel state (figure 4a). For providing the first force F2, the brake actuator 443 requires the energy supply by the main power supply voltage V1. In case of loss of the main power supply voltage V1 , the first force F1 is omitted, resulting automatically in the transfer of the brake roller into the brake state (figure 4b).

According to the description above it becomes clear that upon a loss of the main power supply voltage V1 the objects located on the rollers can be held stationary in their current position on the inclined roller conveyor.

In a first embodiment, in case the main power supply voltage V1 is made available again the brake actuator 443 can immediately provide the first force F1 , so that the brake roller 4 is transferred into the free wheel state. No further problem arises if the motor roller 2 is as well operating immediately properly after the main power supply voltage V1 is made available again. In this embodiment the operating state of the brake roller 4 and of the motor roller 2 are fully synchronous with the availability I non-availability of the main power supply voltage V1.

In a second embodiment, the motor roller 2 has in particular a more complex roller functionality, which is described with reference to figure 5. As soon as the main power supply voltage V1 gets lost at time t1 , a drive power P of the motor is not available anymore. Without the brake roller 4, now the objects 9 would roll down the hill along the inclined conveyor track and may be subject to damage.

It is to be noted that the drive power is not merely used for causing the motor to rotate. Also the drive power P may be used to keep the motor in a hold position. So as long the drive power is available the motor roller can selectively drive the roller tube or keep the roller tube stationary (zero motion hold).

To avoid said damages, in the present application the brake roller 4 is provided. When at time t1 the main power supply voltage V1 gets lost, also the first force F1 is omitted. Now the second force F2 transfers the brake roller at time t1 into the brake state (figure 6).

At time t2 the main supply power voltage V1 is made available again. In particular in case the motor roller is controlled via an external bus connection, the motor roller 4 requires a particular initialization period, from the point in time at which the main power supply voltage V1 is available. So there remains a certain motor delay time dt2, until the motor 24 is actually again providing drive power P to the motor roller 2. This comprises also the possibility that the motor keeps the roller tube stationary without rotation (zero motion hold).

In case the brake would at time t2 immediately transfer the brake roller 4 back into the free wheel state, the objects 9 would roll down the hill along the inclined conveyor track and may be subject to damage. To avoid this disadvantage, between the brake actuator 443 and the main power supply 14 a delayer 46 is arranged (figures 3 and 4).

The delayer 46 is adapted to delay an availability of a supply voltage to the brake actuator 443. In particular the delayer 46 provides a brake power voltage V4 as a function of the availability of the main power supply voltage V1 , as shown in figure 6.

In the event of a loss of main power supply voltage V1 the brake power voltage V4 is immediately reduced at time t1 in a manner, so that there the brake actuator 443 cannot keep the brake roller in the free wheel state by a providing a sufficient second force F2.

When at time t2 the main power supply voltage V1 is available again, the delayer 46 prevents, that the brake actuator 443 is provided with sufficient brake power voltage V4. Only after a further brake delay time dt4 the delayer 46 will provide the brake power voltage V4 to the brake actuator 443 at time t3.

Ideally the brake delay time dt4 is similar to the motor delay time dt2, so that the brake 44 releases at the same time when the motor roller 2 starts conveying.

It is also possible that the brake delay time dt4 is larger than the motor delay time dt2. In this case the brake roller counteracts the operation of the motor roller leading to a certain slippage in the drive connection between the brake 44 and the motor 24.

It is also possible but of minor preference that the brake delay time dt4 is slightly smaller than the motor delay time dt2. Here merely a very small deviation may be acceptable to avoid damages to the objects 9.

The delayer 46 comprises input means 461, exemplarily illustrated in figure 4 as a rotary knob. Any other suitable means may be used as well.

During installation of the conveyor arrangement 1 the motor delay time dt2 is determined in particular by trial or with the help of a look up table. Based on the determined motor delay time dt2 the brake delay time dt4 is set in the delayer 46. Thereby, preferably the brake delay time dt4 is not shorter than the motor delay time dt2. From the above description and in particular figure 3 is becomes apparent, that there is no data connection provided between the brake 44 or the brake roller 4 to the conveyor control 13 or the motor controller 26. In addition there is not linkage between controlling the motor and controlling the brake. The brake roller is only connected to the main power supply. This enables an easy and safe installation without the need to provide and configure any defined data interfaces between a) the motor 2, the motor controller 26 and/or the conveyor control 13 and b) the brake roller 4. Installation can be done simply by connecting the brake roller to the main power supply.

In particular the delayer 46 is considered as a component of the brake roller 4 even if it is located outside of the roller tube 42.

List of reference signs

1 roller conveyor

2 motor device I motor roller

3 idler roller

4 brake roller

5 motor controller

6 control line

7 brake controller

8 brake line

9 object to be conveyed

10 supporting frame

11 drive segment

12 control line

13 conveyor controller

14 main power supply

15 emergency stop button

21 drive connector (Poly V belt)

22 roller tube

23 axle element

24 motor

25 coupler

26 motor controller

27 motor power line

28 motor control line

42 roller tube

43 axle element

44 brake

441 first brake element

442 second brake element

443 brake actuator

444 brake spring

45 coupler

46 brake power delayer

461 input means 47 brake power line

D conveying direction

V1 main power supply voltage

V4 brake power supply

P drive power of motor dt2 motor delay time dt4 brake delay time