Power supply device in a coating robot

Abstract

The invention relates to a power supply device for supplying power to an electrical load in a coating robot, comprising an electrical generator (12, 20) for generating power and a braking device (17, 23, 24) for braking the electrical generator (12, 20) in order to avoid an overspeed of the electrical generator (12, 20).

Description

[0001] DESCRIPTION

[0002] Power supply device in a coating robot

[0003] Technical field of the invention

[0004] The invention relates to a power supply device for supplying power to an electrical consumer (e.g. sensor) in a coating robot (e.g. painting robot).

[0005] Background of the invention

[0006] WO 2022 / 157095 A1 discloses a painting robot that can be used for painting motor vehicle body components in a painting system. This known painting robot contains several electrically operated sensors (e.g., pressure sensors) in its distal robot arm ("Arm 2"). The electrical energy required to operate the sensors is provided by an electrical generator, which is also arranged in the distal robot arm of the painting robot. The mechanical drive of the electrical generator is provided by a compressed air turbine, which is supplied with compressed air at a constant air pressure of, for example, 6 bar from the compressed air network of the painting system.

[0007] However, during operation of this paint shop, the electric generator may overspeed, resulting in corresponding overvoltages in the generator windings. In the worst case, these overvoltages can lead to sparks that may be sufficient to ignite the solvent-based vapors generated during painting, which must be prevented at all costs for safety reasons.

[0008] Furthermore, with regard to the general technical background of the invention, reference should also be made to DE 10 2008 020 731 A1 and DE 1488 788 B. However, these publications concern a completely different technical field (wind turbines) or have no connection whatsoever to the technical field of the invention.

[0009] Description of the invention The invention is therefore based on the object of preventing dangerous sparking in an electrical generator in a painting robot.

[0010] This object is achieved by a power supply device according to the invention according to the main claim.

[0011] The power supply device according to the invention is designed in accordance with the prior art described at the outset to supply an electrical consumer (e.g. sensor) in a coating robot (e.g. painting robot) with the electrical energy required for operation.

[0012] For this purpose, the power supply device according to the invention, in accordance with the prior art described at the outset, has an electrical generator in order to generate the electrical energy required to operate the electrical consumer (e.g. sensor).

[0013] The power supply device according to the invention is distinguished from the prior art described above by a braking device that can decelerate the electric generator to prevent excessive speed of the electric generator and the associated overvoltages. In the power supply device according to the invention, the electric generator no longer rotates freely according to the air pressure provided to drive the electric generator. Instead, the electric generator is braked by the braking device to prevent dangerous excessive speeds.

[0014] In a preferred embodiment of the invention, the braking device for braking the electric generator comprises an eddy current brake. Such eddy current brakes are known per se from the prior art and therefore need not be described in detail.

[0015] Furthermore, the power supply device according to the invention, in accordance with the prior art described above, comprises a drive motor for mechanically driving the electric generator. The drive motor is preferably a compressed air turbine having a rotatable turbine wheel driven by compressed air. The compressed air for driving the compressed air turbine can be provided by the normal compressed air network of the painting system, as is known per se from the prior art.

[0016] The eddy current brake mentioned above for braking the electric generator usually has a rotating brake disc made of an electrically conductive material, whereby the brake disc rotates with the electric generator. At least one magnet is arranged on the brake disc, which generates a magnetic field that permeates the brake disc and thereby induces eddy currents in the brake disc during the rotation of the electric generator, generating a braking torque. The turbine wheel of the compressed air turbine preferably also forms the brake disc of the eddy current brake. The turbine wheel therefore preferably has two functions. Firstly, the turbine wheel serves as the mechanical drive and is blown by compressed air for this purpose. Secondly, the turbine wheel also forms the brake disc of the eddy current brake.

[0017] The aforementioned magnet of the eddy-current brake is preferably arranged axially in front of the brake disc or axially behind the brake disc. Alternatively, however, it is also possible for the magnet to be arranged radially outside the brake disc, i.e., on the outside of the brake disc.

[0018] In the preferred embodiment of the invention, the braking device (e.g., eddy-current brake) generates a braking torque that increases with the speed of the electric generator. The drive motor for driving the electric generator, in contrast, generates a drive torque that decreases with the speed of the electric generator or is essentially independent of the speed. Therefore, the braking device, together with the drive motor, forms a speed controller that sets an operating speed of the electric generator at which the drive torque and the braking torque are essentially equal.

[0019] It should be noted that, due to its design, the electric generator has a specific permissible maximum speed, with the regulated operating speed being lower than the maximum speed. This ensures that the permissible maximum speed is not exceeded during operation of the electric generator, thus preventing overvoltages that could, in the worst case, lead to sparking. The permissible maximum speed is determined by the speed capability of the electric generator or by the maximum permissible output voltage of the electric generator.

[0020] It was already mentioned above that the compressed air for driving the compressed air turbine is provided by a compressed air source, in particular from the normal compressed air network of the painting system, wherein the compressed air source preferably provides the compressed air at a substantially constant pressure of, for example, 6 bar. Thus, with the power supply device according to the invention, it is not necessary to regulate the air pressure of the compressed air provided for the drive in order to avoid overspeed. Rather, a constant air pressure can be used for the drive, since the braking device according to the invention prevents disruptive overspeed.

[0021] In general, it should be noted that the braking device preferably operates wear-free, as is the case with an eddy current brake.

[0022] The electrically conductive material of the brake disc of the eddy current brake is preferably a metal.

[0023] Furthermore, it should be generally noted that the electrical load is preferably a sensor, such as a pressure sensor. However, in a preferred embodiment of the invention, several electrical loads are provided, for example, several sensors. Furthermore, it should be noted that the invention is not limited to sensors with regard to the type of electrical load, but can also be implemented with other electrical loads.

[0024] Furthermore, it should be mentioned in general that the compressed air turbine and the electric generator are preferably arranged in a common housing and then together form a pneumatic power generator.

[0025] The electrical generator can be, for example, a direct current generator or an alternating current generator.

[0026] It should be noted that the electrical generator preferably provides a low voltage output voltage that is less than 1000 VDC (DC: Direct Current) or 1500 VAC (AC: Alternating Current). Therefore, within the scope of the invention, the electrical generator is not typically used to generate the high voltage for electrostatic coating agent charging.

[0027] Furthermore, it should be noted that the invention not only claims protection for the above-described power supply device according to the invention. Rather, the invention also claims protection for a coating robot (e.g., a painting robot) with such a power supply device. The coating robot according to the invention typically includes a robot base and several movable robot elements, such as a proximal robot arm ("arm 1"), a distal robot arm ("arm 2"), and a multi-axis robot wrist axis. The above-described power supply device according to the invention is preferably arranged in the coating robot, for example, in the distal robot arm of the coating robot.

[0028] The coating robot according to the invention preferably has a charging device for charging the coating agent to a high-voltage potential, as is known per se from the prior art, in order to increase application efficiency and minimize disruptive overspray. The coating robot comprises an electrically grounded area, which is preferably located in the robot base or in the proximal robot arm of the coating robot. Furthermore, the coating robot preferably contains an area at high-voltage potential during operation, particularly in the distal robot arm of the coating robot.Between the area at high voltage potential and the electrically grounded area there is an insulation device for electrical insulation between the grounded area and the area at high voltage potential, wherein the insulation device is preferably located in the distal robot arm.

[0029] The electrical load (e.g., sensor) is typically located in the high-voltage area of ​​the coating robot, for example, in the distal robot arm. The same preferably applies to the electrical generator, which is also preferably located in the distal robot arm. The electrical load is supplied with the electrical energy required for operation by the electrical generator.

[0030] The compressed air turbine for driving the electric generator is preferably also located in the high-voltage area of ​​the coating robot, for example, in the distal robot arm of the coating robot. The compressed air for driving the compressed air turbine is supplied via a compressed air line from the electrically grounded area of ​​the coating robot, which is why the compressed air line is preferably made of an electrically insulating material.

[0031] Furthermore, the coating robot according to the invention preferably has a transmitting device for transmitting data (e.g., measurement data) from the electrical load (e.g., pressure sensor) in the high-voltage area of ​​the coating robot to an evaluation device, which is preferably located in the electrically grounded area. The transmitting device is connected to the evaluation device via a transmission path, wherein the transmission path preferably comprises an optical fiber or a radio link to enable potential isolation between the transmitting device in the high-voltage area of ​​the coating robot, on the one hand, and the evaluation device in the electrically grounded area of ​​the coating robot, on the other hand.

[0032] Finally, the invention also claims protection for the use of a braking device (e.g. eddy current brake) for braking an electric generator in a coating robot (e.g. painting robot).

[0033] Other advantageous developments of the invention are characterized in the subclaims or are explained in more detail below together with the description of the preferred embodiment of the invention with reference to the figures.

[0034] Brief description of the drawings

[0035] Figure 1 shows a perspective view of a painting robot according to the invention.

[0036] Figure 2 shows a schematic representation of the painting robot from Figure 1.

[0037] Figure 3A shows a sectional view through the pneumatic power generator of the painting robot from Figures 1 and 2.

[0038] Figure 3B shows an enlarged sectional view of Figure 3A in the area of ​​an eddy current brake.

[0039] Figure 4 shows a schematic representation of a torque-speed characteristic curve of the pneumatic power generator with the eddy current brake.

[0040] Detailed description of the drawings

[0041] In the following, the embodiment of a painting robot 1 according to the invention shown in the drawings will be described, as it is already partially described in the earlier patent application WO 2022 / 157095 A1, so that in order to avoid repetition, reference is also made to this earlier patent application, the content of which is to be fully incorporated into the present description.

[0042] The painting robot 1 is partially of conventional construction and has a robot base 2, which can be either fixedly mounted or movable along a travel rail (not shown).

[0043] A rotatable robot link 3 is mounted on the robot base 2 and can rotate about a vertical axis of rotation.

[0044] The rotatable robotic member 3 carries a proximal robotic arm 4 ("arm 1"), which can be pivoted about a horizontal pivot axis.

[0045] A distal robot arm 5 ("Arm 2") is pivotably mounted at the end of the proximal robot arm 4.

[0046] At the end of the distal robot arm 5, a multi-axis robot hand axis 6 is attached, which guides a rotary atomizer 7 with high mobility.

[0047] Located in the distal robot arm 5 of the painting robot 1 are several sensors 8-11 that can detect various operating variables of the painting robot 1, such as steering air pressure, paint pressure, or paint flow, to name just a few examples. The sensors 8-11 require electrical energy to operate, which is provided by a pneumatic power generator 12 via a collection device 13. The pneumatic power generator 12 thus initially supplies the electrical energy to the collection device 13, which then supplies the sensors 8-11 with the electrical energy required for operation.

[0048] The pneumatic power generator 12 is also housed in the distal robot arm 5.

[0049] Located in the proximal robot arm 4 is an evaluation device 14, which is connected via an optical fiber 15 to a transmitting device in the collecting device 13. The collecting device 13 receives measured values ​​for the respective operating parameters of the painting robot 1 from the sensors 8-11 and transmits them via the optical fiber 15 to the evaluation device 14. It should be noted that the paint applied by the painting robot 1 is electrostatically charged in order to increase the application efficiency and avoid disruptive overspray, as is known per se from the prior art. A high-voltage generator (not shown) is used for this purpose. Due to this electrostatic paint charge, the distal robot arm 5 is essentially at a high-voltage potential, while the proximal robot arm 4, the rotatable robot link 3, and the robot base 2 are electrically grounded.At the proximal end of the distal robot arm 5 there is an insulation device in order to electrically insulate the area of ​​the painting robot 1 which is at high voltage potential from the electrically grounded area of ​​the painting robot 1.

[0050] The pneumatic power generator 12 is housed together with a compressed air turbine in a common housing 16, as shown in Figure 3A. Located within the housing 16 is a rotatable turbine wheel 17 with turbine blades 18, which are distributed around the circumference of the turbine wheel 17 and, during operation, are blown with compressed air supplied via an air supply 19 from the compressed air network of the painting system.

[0051] The turbine wheel 17 is mechanically connected to an electric generator 20, which in turn is surrounded by a sleeve 21 for cooling.

[0052] Furthermore, it should be mentioned that the housing 16 of the pneumatic power generator 12 is closed by a cover 22.

[0053] Also located in the housing 16 is an eddy-current brake, which serves to decelerate the turbine wheel 17. The eddy-current brake comprises several bar magnets 23, 24 arranged next to the turbine wheel 17. These magnets generate a magnetic field that permeates the turbine wheel 17, thus inducing eddy currents in the electrically conductive turbine wheel 17. The turbine wheel 17 thus also functions as a brake disc for the eddy-current brake.

[0054] The characteristic curve diagram shown in Figure 4 is now explained. It should be noted in advance that the characteristic curves shown are only schematic and serve only to explain the control principle according to the invention. In practice, the characteristic curves shown may have a quantitatively different shape.

[0055] On the one hand, the characteristic diagram shows the speed-dependent course of a drive torque MANTRIEB of the turbine wheel 17 as a function of the speed n.

[0056] On the other hand, the characteristic diagram shows the speed-dependent course of a braking torque MBREMS of the eddy current brake as a function of the speed n.

[0057] This shows that the braking torque MBREMS of the eddy-current brake increases with speed n, while the drive torque MANTRIEB decreases with speed n. This results in a stable operating point 25, in which the drive torque MANTRIEB and the braking torque MBRE S are essentially equal. The eddy-current brake, together with the pneumatic power generator 12, forms a controller that maintains a constant operating speed H N ENN which is below the maximum permissible speed n MAx, above which, in the worst case, sparking could occur. The invention thus prevents the disruptive overspeed of the pneumatic power generator 12 without requiring the air pressure of the compressed air used for propulsion to be regulated.

[0058] The invention is not limited to the preferred embodiment described above. Rather, a multitude of variants and modifications are possible, which also utilize the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and features of the subclaims, independently of the respective claims referred to, and in particular even without the features of the main claim. The invention thus encompasses various aspects of the invention that enjoy independent protection.

[0059] Advantages of

[0060] The braking device according to the invention (e.g., eddy-current brake) advantageously prevents dangerous overspeeds and corresponding overvoltages in an electric generator used for power supply. This reliably prevents sparking that could lead to the ignition of solvent-containing vapors in a paint shop.

[0061] A particularly advantageous feature is that it is not necessary to regulate the compressed air used to drive the pneumatic power generator. Instead, the pneumatic power generator can be supplied with compressed air from the paint shop's standard compressed air network at a constant pressure of, for example, 6 bar. Furthermore, it is advantageous that the eddy current brake according to the invention operates wear-free, can be implemented cost-effectively, and requires no mechanical components on the rotor and stator.

[0062] List of reference symbols

[0063] 1 painting robot

[0064] 2 Robot base of the painting robot

[0065] 3 Rotating robot link of the painting robot

[0066] 4 Proximal robot arm of the painting robot

[0067] 5 Distal robot arm of the painting robot

[0068] 6 robot hand axis

[0069] 7 rotary atomizers

[0070] 8-11 sensors in the distal robot arm

[0071] 12 Pneumatic power generator in the distal robot arm

[0072] 13 Collection device in the distal robot arm

[0073] 14 Evaluation device in the proximal robot arm

[0074] 15 optical fibers

[0075] 16 Housing of the pneumatic power generator

[0076] 17 Turbine wheel in the pneumatic power generator to drive the electric generator

[0077] 18 turbine blades of the turbine wheel

[0078] 19 Air supply for the pneumatic power generator

[0079] 20 Electric generator in the pneumatic power generator

[0080] 21 Sleeve for cooling

[0081] 22 Housing cover

[0082] 23, 24 Bar magnets of the eddy current brake

[0083] 25 Operating point of the pneumatic power generator

[0084] M torque

[0085] MANTRIEB Drive torque of the compressed air turbine

[0086] MBREMS Braking torque of the eddy current brake n Speed ​​of the n M Ax maximum permissible speed n N ENN operating speed

Claims

CLAIMS 1. Power supply device for supplying power to an electrical consumer in a coating robot (1), in particular in a painting robot (1) for painting motor vehicle body components, with a) an electrical generator (12, 20) for generating power, characterized by b) a braking device (17, 23, 24) for braking the electrical generator (12, 20) to avoid an overspeed of the electrical generator (12, 20).

2. Power supply device according to claim 1, characterized in that the braking device (17, 23, 24) has an eddy current brake (17, 23, 24).

3. Power supply device according to one of the preceding claims, characterized by a drive motor (17, 18, 19) for mechanically driving the electric generator (12, 20).

4. Power supply device according to claim 3, characterized in that the drive motor (17, 18, 19) is a compressed air turbine having a rotatable turbine wheel (17) which is blown by compressed air.

5. Power supply device according to claim 4, characterized in that a) the eddy current brake (17, 23, 24) has a brake disc (17) made of an electrically conductive material which rotates with the electrical generator (12, 20), and b) at least one magnet (23, 24) is arranged on the brake disc (17), the magnet generating a magnetic field which penetrates the brake disc and thereby induces eddy currents in the brake disc (17) during the rotational movement of the electrical generator (12, 20), and c) the turbine wheel (17) of the compressed air turbine forms the brake disc (17) of the eddy current brake (17, 23, 24), d) the magnet (23, 24) is preferably arranged axially in front of the brake disc (17) or axially behind the brake disc (17) or radially outside the brake disc (17).

6. Power supply device according to one of claims 3 to 5, characterized in that a) the braking device (17, 23, 24) generates a braking torque (MBRE S) which increases with the speed (n) of the electrical generator (12, 20), and / or b) the drive motor (17, 18, 19) generates a driving torque (MANTRIEB) which decreases with the speed (n) of the electrical generator (12, 20) or is essentially independent of the speed, and / or c) the braking device (17, 23, 24) together with the drive motor (17, 18, 19) forms a speed controller which sets an operating speed (ONENN) of the electrical generator (12, 20) at which the driving torque (MANTRIEB) and the braking torque (MBREMS) are essentially equal, and / or d) the electrical generator (12, 20) has a design-related permissible maximum speed (n M Ax), wherein the controlled operating speed (O N ENN) is smaller than the maximum speed (n MAx), and / or e) that the maximum permissible speed (n M Ax) is determined by the speed stability of the electric generator (12, 20) or by the maximum permissible output voltage of the electric generator (12, 20).

7. Power supply device according to one of claims 4 to 6, characterized in that a) the compressed air for driving the compressed air turbine (17-19) is provided by a compressed air source, in particular by a compressed air network in a painting system, and b) that the compressed air source provides the compressed air at a substantially constant pressure.

8. Power supply device according to one of the preceding claims, characterized in that a) the braking device (17, 23, 24) operates wear-free, and / or b) the electrically conductive material of the brake disc (17) of the eddy current brake (17, 23, 24) is a metal, and / or c) the at least one electrical consumer is a sensor (8-11), in particular a pressure sensor, and / or d) the compressed air turbine (17-19) and the electrical generator (12, 20) are arranged in a common housing (16), and / or e) the electrical generator (12, 20) is a direct current generator or an alternating current generator, and / or f) that the electrical generator (12, 20) supplies as output voltage a low voltage which is less than 1000 VDC or 1500 VAC.

9. Coating robot (1) for coating components with a coating agent, in particular a painting robot (1) for painting motor vehicle body components, with a) a robot base (2), b) a plurality of movable robot members, in particular b1) a rotatable robot member (3), b2) a proximal robot arm (4), b3) a distal robot arm (5), and / or b4) a multi-axis robot hand axis (6), and c) a power supply device according to one of the preceding claims, wherein the power supply device is arranged in the coating robot (1), in particular in the distal robot arm (5) of the coating robot (1).

10. Coating robot (1) according to claim 9, characterized by a) a charging device for electrostatically charging the coating agent to a high-voltage potential, b) an electrically grounded region of the coating robot (1), in particular in the robot base (2), the rotatable robot member (3) and / or in the proximal robot arm (4) of the coating robot (1), c) a region of the coating robot (1) which is at high-voltage potential during operation, in particular in the distal robot arm (5) of the coating robot (1), and d) an insulation device for electrical insulation between the grounded region of the coating robot (1) and the region of the coating robot (1) which is at high-voltage potential, wherein the insulation device is preferably arranged in the distal robot arm (5).

11. Coating robot (1) according to claim 10, characterized in that a) the electrical consumer (8-11) is arranged in the area of ​​the coating robot (1) which is at high voltage potential, in particular in the distal robot arm (5), b) the electrical generator (12, 20) is arranged in the area of ​​the coating robot (1) which is at high voltage potential, in particular in the distal robot arm (5), and c) that the electrical consumer (8-11) is supplied by the electrical generator (12, 20) with the electrical energy required to operate the electrical consumer (8-11).

12. Coating robot (1) according to claim 11, characterized in that a) the electrical generator (12, 20) with the compressed air turbine (17-19) is arranged in the area of ​​the coating robot (1) which is at high voltage potential, in particular in the distal robot arm (5) of the coating robot (1), b) the compressed air for driving the compressed air turbine is supplied via a compressed air line, c) the compressed air line leads from the electrically earthed area of ​​the coating robot (1) to the compressed air turbine in the area of ​​the coating robot (1) which is at high voltage potential, and d) the compressed air line consists of an electrically insulating material.

13. Coating robot (1) according to one of claims 9 to 12, characterized by a) a transmitting device (13) for transmitting data from the electrical load (8-11) in the area of ​​the coating robot (1) at high voltage potential, in particular in the distal robot arm (5) of the coating robot (1), b) an evaluation device (14) for receiving and evaluating the data transmitted by the electrical load (8-11), wherein the evaluation device (14) is arranged in the electrically grounded area of ​​the coating robot (1), in particular in the robot base (2), in the rotatable robot member (3) or in the proximal robot arm (4), c) a transmission path (15) connecting the transmitting device (13) to the evaluation device (14) in order to transmit the data from the electrical load to the evaluation device,d) wherein the transmission path (15) preferably comprises an optical fiber (15) or a radio link in order to enable potential separation between the transmitting device (13) and the evaluation device (14).

14. Use of a braking device (17, 23, 24), in particular an eddy current brake (17, 23, 24), for braking an electrical generator (12, 20) in a coating robot (1), in particular in a painting robot (1) for painting motor vehicle body components.

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