WO2021219200A1

WO2021219200A1 - Drive device for a robotic joint

Info

Publication number: WO2021219200A1
Application number: PCT/EP2020/061729
Authority: WO
Inventors: Georg Bachmaier; Christian Bachmann; Dominik Bergmann; Gerit Ebelsberger; Reinhard Freitag; Matthias Gerlich; Christian Mose; Thomas Vontz; Wolfgang Zöls
Original assignee: Rethink Robotics Gmbh
Priority date: 2020-04-28
Filing date: 2020-04-28
Publication date: 2021-11-04

Abstract

The invention describes a drive device (1) for a robotic joint (J1-J7). The drive device (1) comprises: - a drive motor (5) having a drive shaft (7) which can be rotated with respect to a central axis (A); - a transmission (50) having a fixed element (51), a drive element (52), and an output element (53), the drive element (52) being connected to the drive shaft (7) of the drive motor (5) in a torque-transmitting manner; - and a braking device (8) for braking the rotational movement of the drive shaft (7), the braking device (8) being positioned axially between the drive motor (5) and the transmission (50). The invention also relates to a robotic joint (J3) comprising such a drive device (1).

Description

description

Drive device for a robotic joint

The present invention relates to a drive device for a robotic joint with a drive motor and a gear unit.

Numerous robot arms are known from the prior art, such a robot arm typically having a plurality of robotic joints and each of these Robotikge joints enables a rotational movement with respect to a rotational degree of freedom. For this purpose, such a Robotikge has a drive device for a rotary movement. The se rotary movement is brought about by a drive motor with which a drive shaft is rotated. The speed can be changed with a gear unit downstream of the motor and set accordingly to a desired range of values for the output side.

Such conventional robotic arms or robotic joints are often used in industrial production. However, many of them cannot be used, or only to a limited extent, as collaborative robots ("cobots" for short) because they do not adequately meet the safety requirements for collaborative cooperation between robots and human workers Among other things, movement of the robot arm can be stopped as immediately as possible in the event of a fault or danger. To enable this, an active brake can be provided in the area of the articulated drive. Such brakes are also used in conventional (not collaborative They are often arranged on the output side of such a robotic joint, since braking in this area effectively protects the robotic joint itself from damage in the event of a malfunction The aim of such safety devices This means that in the event of a malfunction, the affected robot arm should not collapse and thus prevent damage to the arm or its joints. Many conventional robots also have no brake at all, but at most one lock, which can be arranged, for example, on the drive side and can only hold the robot arm in a predetermined stationary position.

A disadvantage of the conventional robotic drives with such an active braking device is that this braking device typically has a high intrinsic mass and requires a comparatively large installation space. This leads to an undesirable increase in mass and / or installation space of the entire robotic joint.

The object of the invention is therefore to provide a drive device for a robotic joint which overcomes the aforementioned parts. In particular, a drive device is to be made available which enables active braking of the rotational movement that has been effected and yet still has a low intrinsic mass and / or an overall compact design. Another object is to provide a robotic joint with such a drive device.

These objects are achieved by the drive device described in claim 1 and the robotic joint described in claim 15.

The drive device according to the invention is designed as a drive device for a robotic joint and, in particular, is dimensioned accordingly for this application. It comprises a drive motor with a drive shaft which is rotatable with respect to a central axis A. It further comprises a transmission with a fixed element, a drive element and an output element, the drive element being connected to the drive shaft of the drive motor in a torque-transmitting manner. It further comprises a braking device for braking the rotational movement of the drive shaft, wherein the Braking device is arranged axially between the drive motor and the Ge gear.

For the entire drive device, a motorseiti ges axial end al is defined by the axial position of the drive motor (with respect to the transmission). The opposite axial end is referred to below as the output-side axial end a2, since in this area the rotary movement is typically diverted by a rotating output body.

The drive motor can in particular be an electric motor. This can comprise a rotor and a stator. The transmission can expediently increase or decrease the speed between the drive shaft of the motor and an output body connected to the output element. The torque on the output side is also changed. In the case of the robotic drives considered here, the transmission typically and generally advantageously brings about a reduction in the speed and an increase in the torque on the output side. The fixed element of the transmission is generally used to connect it to the mechanical mass of the drive device.

The arrangement according to the invention of the braking device axially between the drive motor and the gearbox enables the rotary movement to be braked in the area of the comparatively higher speed and the comparatively lower effective torque. The braking device can therefore in particular act directly on the drive shaft and thus on the drive side of the drive device, where it brakes the torque on the drive side. Thus, the braking device can be designed for braking a comparatively low torque. If only a low torque needs to be braked, the required braking device can be made correspondingly small and light. This results in a particularly compact and / or particularly light design of the entire drive device. device allows, the safety-relevant function of the braking device is still fulfilled. The braking device makes it possible in particular to use the drive device as a drive in a robotic joint of a collaborative robot arm (ie a "cobot") of the robot arm can be stopped very quickly and effectively. It is therefore particularly preferred if the braking device is controlled by a control device to which the output values of an optional measuring device for an internal torque are fed Torque take place, which enables an automatic determination of a fault or dangerous condition.

The robotic joint according to the invention has a drive device according to the invention. The advantages of the robotic joint according to the invention arise analogously to the above-described advantages of the drive device according to the invention. In addition to the drive device described, the robotic joint can have further mechanical elements, for example a connecting member and / or a base element for connecting to neighboring robotic joints of a robot arm. Such a robot arm, which has at least one such robotic joint, should also generally be regarded as an object according to the invention. In the case of such a robot arm, several (and in particular even all) existing robotics joints can advantageously be configured in the manner described.

Advantageous refinements and developments of the invention emerge from the claims dependent on claim 1 and the following description. The described configurations of the drive device, the Robotikge steering and / or the robot arm can generally advantageously be combined with one another. Thus, according to a generally advantageous embodiment, the braking device can be arranged axially adjacent to the drive motor. In other words, the braking device then lies directly next to the drive motor, so that no other functional element lies in between. An advantage of this directly adjacent arrangement is that it enables a particularly compact, space-saving integration of the braking device into the drive device.

In a further generally advantageous embodiment, the braking device comprises an electromagnetic brake with at least one brake disc and at least one electromagnetic field coil. The at least one brake disc is in particular connected firmly and torque-transmitting to the drive shaft. It therefore belongs to the (typically) rapidly rotating part of the drive device. The at least one field coil is designed in particular as a fixed component of the drive device. For example, this field coil (or more generally: the entire stationary part of the braking device) can be firmly connected to the stator of the drive motor.

In general and regardless of the exact design and the exact operating principle of the braking device, it can be designed as a safety brake. A safety brake should be understood to mean a braking device that is closed in the de-energized state ("normally closed"). If, in the event of a malfunction, the voltage applied to the field coil or the current flowing through the field coil drops to zero falls off, then the brake closes and the rotary movement stops. Such a fail-safe brake enables reliable braking even under unfavorable conditions and operational disruptions. This embodiment therefore enables the corresponding robotic joint to be used in safety-critical environments, e.g. in a collaborative robot. According to a generally advantageous embodiment, the transmission is a single-stage transmission, in particular a Harmonie Drive transmission. Such a transmission is also referred to in German as a stress wave transmission. In particular, the fixed element can then be formed by a circular spline of the harmonic drive transmission. The drive element can be formed by a wave generator and the output element can be formed by a flex spline of this gear. Such a Harmonie Drive transmission in particular enables the implementation of a drive device with a relatively high gear ratio. With such a gear, the speed between drive and output can be reduced by a factor of about 100, for example. Alternatively, however, other configurations of the transmission are also possible, for example as a planetary transmission.

Furthermore, it is generally advantageous if the drive device has a bearing shaft fixedly connected to the output element of the transmission, which shaft extends in the axial direction at least over the axial regions of the drive motor, the braking device and the transmission. This bearing shaft can be connected to the output element of the transmission either directly or via one or more optional intermediate elements (for example an output body and / or one or more ring elements). This bearing shaft can in particular be passed radially on the inside through the drive motor, the braking device and the transmission. It rotates together with the output body without a torque necessarily being diverted via this bearing shaft. In particular, it is referred to as a "bearing shaft" because the drive shaft rotating at a different and, in particular, higher speed can be rotatably mounted on it The bearing shaft can be rotatably supported by one or more radial bearings. In addition to the axial areas of the drive motor, the braking device and the gearbox, the bearing shaft can advantageously also extend over the axial areas of other optional elements, namely the area of a motor-side rotary encoder, a spoked wheel for internal torque measurement, a disk element of a Basic holder, an output-side radial bearing and / or an output-side rotary encoder. Particularly advantageously, the La gerwelle can extend axially over the areas of all elemen mentioned.

According to an advantageous variant of the bearing shaft, it can be designed as a hollow shaft, in particular over its entire axial length. One advantage of this embodiment variant is that one or more electrical connecting lines can then be routed inside this hollow shaft. Through this connection line (s), for example, the successive joint drives of a robot arm can be electrically connected to one another and / or connections can be implemented across the individual joints. As a result, the electrical energy supply of the individual Ge joint drives and / or communication with the joint drives can be ensured in particular. This can, for example, be communication of the articulated drives with an external control unit and / or communication of the individual joints with one another and / or communication with a camera arranged on the outermost joint and / or an end effector arranged there with a control unit by the da between the robotic joints.

In this way, electrical or electronic elements can be connected to one another in a particularly simple manner on both axial sides of the drive device. It can advantageously be fixed (that is, non-rotating) electrical connection lines. Furthermore, the cavity lying within the bearing shaft can generally advantageously be part of an unlubricated partial area of the drive device. According to a further advantageous embodiment variant, the drive device can have a rotary encoder in the motor-side end region for determining the angular position of the bearing shaft and / or the drive shaft. The angular position of the drive shaft is particularly advantageously measured here. For this purpose, the rotary encoder on the motor side is preferably arranged on the front side (that is to say axially offset) next to it. With such a rotary encoder, an angle of rotation or a speed of the typically rapidly rotating drive can be determined. According to a further alternative, the motor-side encoder can also be designed to measure the angular position of the bearing shaft. Alternatively, there can also be two rotary encoders in the motor-side end area, one of which is designed to measure the angular position of the bearing shaft and one of which is designed to measure the angular position of the drive shaft. The rotary encoder (s) on the motor side can be arranged particularly advantageously in the axial direction between the drive motor and an optionally present control device.

Generally and independently of the presence of a bearing shaft and / or a rotary encoder, it is advantageous if the drive device comprises a control device for controlling the drive motor and / or the braking device. This control device can be arranged particularly advantageously in the motor-side end region of the drive device. For example, it can comprise a control board, one or more converters, one or more readout elements of the at least one rotary encoder and / or a communication interface. In other words, it can be a central control device of the drive device.

According to a further embodiment, the drive device can include a rotary encoder in the output-side end region of the bearing shaft for determining the angular position of the bearing shaft. This output-side rotary encoder can be present as an alternative or in addition to the described motor-side rotary encoder. If there are a total of several rotary encoders, this has the advantage that, by interpolating the signals, the With both rotary encoders, increased accuracy can be achieved in determining the overall angular position of the drive device.

The axial position of the optional output-side rotary encoder can particularly advantageously lie between a radial bearing for mounting the bearing shaft and the output-side axial end region of the drive device. Said Radi allager is provided in particular for the rotatable mounting of the La gerwelle against the stationary part of the drive device. The described terminal positions of the two rotary encoders advantageously enable an angle measurement near the axial ends of the bearing shaft.

Generally advantageously and independently of the presence of a bearing shaft, the drive device can have an output body which is rotatably supported by a radial bearing on the output side. In this context, "on the output side" should be understood to mean that this radial bearing is arranged on the side of the transmission facing away from the drive motor. Such an output body can also be composed of several elements In this variant, the bearing shaft is supported together with the output body via this radial bearing.

The radial bearing of the output body is advantageously a roller bearing, in particular a roller bearing and particularly advantageously a crossed roller bearing. The output body can in particular be designed as a hollow shaft, in which case further elements can then be passed through the interior of the hollow shaft, for example one or more electrical connection lines. The fixed part of such a bearing can also be provided by one or more ring elements. The rotatable ring elements of the output body are advantageously radially inner rings, and in the ring elements of the stationary part are advantageously radially outer rings.

Generally advantageously, the drive device can have a base holder for connection to an external mechanical mass. The mechanical mass is understood to be the mechanical reference point for the drive movement. For example, this can be a base of a robotic joint. For a joint further out, the mechanical reference point can also be an output of an adjacent joint or a connec tion element connected to such an output. In any case, the base holder serves as an internal mechanical reference point for the drive device, relative to which an output body rotates.

This basic holder can advantageously have a disk element which is oriented perpendicular to the central axis. This disk element can in particular be arranged axially between the transmission and the radial bearing on the output side. It can therefore serve as an internal mechanical reference point and at the same time divide the drive device axially into an area on the engine side and an area on the output side. The disk element can also be connected to part of a measuring device for measuring an internal torque of the drive device, in particular to a spoked wheel.

In the embodiments with a base holder, this can have a base with a flange for connection to an external component. This outer component can, for example, be a base of a robot arm or also a further inside (trunk-side) robotics joint or a further outside (tool-side) robotics joint of the robot arm. In a first generally advantageous embodiment, the flange can have a flange axis which is perpendicular to the central axis of the drive device. In other words, a 90 ° angle is then created between the connection axis and the axis of rotation of the associated robot tic joint formed. According to an alternative embodiment, however, the flange can also have a flange axis which is essentially parallel to the central axis of the drive device. It is then a coaxial arrangement of the connecting axis and the axis of rotation.

Generally advantageously, the drive device can comprise a measuring device for measuring a torque acting within the drive device. This measuring device can have a spoked wheel as an essential component. The torque transmitted via this spoke wheel is measured by deforming the spokes. This torque can in particular be a transmission support torque. This type of internal torque measurement is described in detail in the patent application filed on the same filing date by the same applicant as "To drive device, robot arm and method for measuring torque", which should therefore be included in the content of the present application.

Generally advantageously, the drive device can have a lubricated and an unlubricated sub-area. These two partial areas can be separated by one or more sealing elements, in particular by

- at least one static seal,

- at least one rotary seal

- And / or at least one sealed radial bearing.

The two partial areas can advantageously be sealed from one another by several such sealing elements, in particular by one or more of all three types of sealing elements mentioned. A static seal should be understood to mean a lubricant-tight connection between two stationary elements. A rotary seal is to be understood as a lubricant-tight seal between two elements rotating relative to one another (without these being integrated into a rotary bearing). A sealed radial bearing should be understood to mean a radial bearing through which ben the mechanical mounting, a fluid-tight seal between the two rotatable elements is given.

The unlubricated sub-area can advantageously include one or more particularly sensitive areas of the drive device. Such a particularly sensitive area is, for example, the area of the rotor and the stator of the drive motor and / or the area of the braking device. Furthermore, these are the areas of the following optionally present lowing elements: a control device, a motor-side and / or output-side rotary encoder and the area of an axially internally guided electrical line. The unlubricated partial area preferably comprises the areas of several (and in particular even all) of the particularly sensitive elements mentioned. These sensitive elements are advantageously protected from the influences of the external environment by one or more moisture and dustproof seals.

The invention is described below on the basis of a few preferred exemplary embodiments with reference to the attached drawings, in which:

Figure 1 shows a schematic longitudinal section of a drive device according to a first example of the invention,

Figure 2 shows a longitudinal section of a drive device according to a second embodiment,

Figure 3 shows an exploded view of a similar drive mechanism,

FIG. 4 illustrates various partial areas for the drive device of FIG. 2 and

FIG. 5 shows a schematic perspective illustration of a robot arm.

Identical or functionally identical elements are provided with the same reference symbols in the figures. In Figure 1, a drive device 1 is shown according to a first example of the invention. Shown is a schematic longitudinal section along the central axis A. The drive device 1 comprises a drive housing 3, the radially delimiting wall is shown by a dashed line. The drive housing 3 encloses a drive motor 5, a gear 50, a braking device 8 and other, partly optional components. It is therefore a highly integrated drive device, which is here comparatively compact. The torque generated by the drive motor 5 is diverted via a drive shaft 7 and transmitted to a drive element 52 of the transmission 50. The drive shaft 7 is rotatably arranged with respect to the central axis A of the drive device 1. Overall, the drive device 1 has an axial end a1 on the engine side and an axial end a2 on the output side.

The drive motor 5 comprises a stationary stator 5a and a rotor 5b rotatably mounted for this purpose. The stationary stator 5a is firmly connected to the housing 3. In general, the fixed parts are shown in Figure 1 without hatching. The parts rotating at the speed of the rotor 5b, however, are shown with close hatching, and the parts rotating at the (in particular slower) speed of the output element 53 of the transmission 50 are shown with wider hatching.

The braking device 8 is arranged axially between the drive motor 5 and the transmission 50. In particular, it is arranged axially directly adjacent to the drive motor 5, so that there is no further functional element between the drive motor 5 and the braking device 8 (apart from the connecting, torque-transmitting drive shaft 7, which, however, is located radially further inward than the elements 5 and 8 and therefore not immediately in between). The braking device 8 is designed here as an electromagnetic Bremsein direction. It comprises a rotating with the speed of the rotor 5b and attached to the drive shaft 7 activated brake disc 8a. It also comprises a fixed part 8b in which an electromagnetic field coil 8c is integrated. This fixed part 8b of the Bremseinrich device surrounds the drive shaft 7 radially. When the field coil 8c is de-energized, the brake is closed, for example via a spring element, and the rotation of the drive shaft 7 is prevented. So it is a safety brake. The closing of the brake can be brought about, for example, by rubbing the contact between the brake disc 8a and a further sub-element of the stationary part 8b, not shown in detail here. This frictional contact with the brake disc can in principle be one-sided or two-sided mechanical contact of such a fixed braking element with the brake disc. With a suitable energization of the field coil 8c, however, this friction contact is weakened or even completely canceled, so that rotation of the output shaft 7 is made possible in the energized state.

In addition to the drive element 52, the gear 50 also includes an output element 53 and a fixed element 51 as essential components. In the example shown, the gear 50 is designed as a harmony drive gear, the drive element 52 being the wave generator, the Output element 53 forms the flex spline and the fixed element 51 forms the circular spline of this gear. The flex spline here comprises a bushing-like shaped sub-element 53a, which is connected to an output body 40 to transmit torque. From this drive body 40 is shown here as a rotationally symmetrical output shaft, with an enlarged diameter towards the output side a2. In this area, a flange for connection to an outer element to be rotated can also be provided.

The output body 40 is rotatably mounted here by means of a radial bearing 43 against the external fixed elements of the drive device, which are not shown in detail here, these fixed elements being collectively denoted by 44. The radial bearing 43 can be, for example, a crossed roller bearing. The radial bearing 43 can generally advantageously lie on a comparatively large radius.

In addition to radial mounting, it can also be used for axial mounting.

In the example of FIG. 1, the output body 40 is connected to a bearing shaft 45 in a fixed and torque-transmitting manner. The se bearing shaft is designed as a in relation to the drive motor 5, to the braking device 8 and to the gear 50 radially inwardly lowing hollow shaft. In the axial direction, this bearing shaft 45 extends at least over the areas of the drive motor 5, the braking device 8 and the gear 50. One or more electrical connection lines (not shown here) and other optional elements can be routed in its interior. The term "bearing shaft" comes from the fact that the drive shaft 7, which rotates at a different speed (and in particular faster) in relation to it, is rotatably mounted on this bearing shaft via one or more radial bearings 74.

In this example, the drive shaft 7 surrounds the bearing shaft 45 radially and concentrically and is supported rotatably on this in the motor-side area al. The rotatably mounted support at the opposite end of the drive shaft results from the bearing within the transmission 50, not shown here. However, these two rotary encoders are generally optional, and in principle such a rotary encoder would also suffice to determine the angular positions. Both the motor-side encoder 48 and the drive-side encoder 49 are connected here to the stationary parts of the drive device. The motor-side rotary encoder 48 is arranged on the front side adjacent to the rapidly rotating drive shaft 7 and measures its angular position. The output-side rotary encoder 49 is arranged on the front side adjacent to the slowly rotating bearing shaft 45 and measures it Angular position. From the combination and in particular the interpolation of the two measured values of the rotary encoders 48 and 49, the overall state of the system with regard to the angular positions can be determined particularly precisely.

In Figure 1, for the sake of clarity, only the essential fixed, rapidly rotating and slowly rotating elements of the drive device 1 of the first Ausführungsbei are shown game. The drive device can also comprise further optional elements, and the elements shown can be nested in one another in a much more compact manner, in particular in the axial direction. Both of these are illustrated by FIG. 2, in which a similar drive device according to a second exemplary embodiment of the invention is shown in a schematic longitudinal section.

The drive device 1 of FIG. 2 has the same essential core components that have already been described in connection with the simplified FIG. The radially delimiting housing 3 has only been omitted from FIG. 2 for the sake of clarity. The geometric shape of the individual elements already described is shown in more detail here, and further optional elements are shown.

Thus, the drive device 1 in the end region on the motor side has a control device 25, by means of which the drive motor 5 and optionally also the braking device 8 can be controlled. For this purpose, the control device 25 can comprise a control board aligned perpendicular to the axis A and a plurality of electronic compo elements arranged thereon. This can be, for example, one or more converters or other power electronics elements and optionally one or more readout elements for the rotary encoder 48 or 49 and / or a communication interface and / or a control module for controlling parameters such as current, torque, speed or position . The drive device 1 also includes a base holder 20, which is designed in particular for connection to an external mechanical mass. This basic holder 20 thus forms a kind of mechanical reference body of the drive device 1, against which the other elements are supported.

50, for example, the drive motor 5 is supported mechanically against a base 21 of this basic holder via a support element 9 from. This base 21 lies in a radially outer region of the entire drive device 1 and is designed for connection to external elements, for example via a flange 21a. In the example shown, the flange axis B of this flange is perpendicular to the axis of rotation A.

The drive device 1 also comprises a measuring device for measuring a torque acting within the drive device. A spoked wheel 31 forms an essential part of this measuring device. This spoked wheel 31 is designed to transmit a torque between a radially inner and a radially outer area. The torque transmitted by the spoked wheel is the quantity that is measured by the measuring device. In the present example, it is a support torque of the gear 50 against the base holder 20. In order to enable this variable to be measured, the radially outer area of the spoke wheel 31 is fixed and transmits torque with the fixed element

51 of the transmission 50 connected. In addition, the radially inner area of the spoked wheel 31 is firmly connected to the base holder 20 in a torque-transmitting manner. In order to enable the fixed connection with the radially inner part of the spoke wheel 31, the base holder in this example has a disk element 22 which is oriented perpendicular to the central axis A. The principle of this torque measurement is described in detail in the parallel application already cited above with the title "Drive device, robot arm and method for torque measurement". The bearing of the output body 40 against the stationary parts takes place via the already generally described radial bearing 43. The fixed element of the radial bearing is composed of two individual ring-shaped elements: the first outer ring element 44a and the second outer ring element 44b. These two ring elements 44a and 44b are arranged radially on the outside with respect to the radial bearing 43. The inner bearing partner of this radial bearing is again composed of two ring-shaped elements: the first inner ring element 41a and the second inner ring element 41b. These two ring elements 41a and 41b are firmly and torque-transmitting connected to the output body 40 and the output element 53 of the transmission. The connec tion of these output-side, comparatively slowly rotating the elements with one another is conveyed by a gear-side nut ring 54 and a long screw 55 screwed into it.

The mounting of the rapidly rotating drive shaft 7 on the slowly rotating bearing shaft 45 is effected in the example of FIG. 2 by two individual, axially adjacent radial bearings: a first radial bearing 74a arranged in the motor-side end area, which is designed as a sealed bearing, and an adjacent second radial bearing 74a, which can be designed as an unsealed bearing. The sealed radial bearing 74a supports the division of the drive device into a lubricated and an unlubricated area, as will become even clearer in connection with FIG.

In Figure 3, an exploded view of a drive device 1 is shown. The structure of this drive device and the functional principle of the individual components is on the whole analogous to the drive device of FIG. 2. The same reference symbols are therefore also used for all components. FIG. 3 only illustrates once again the relative axial or radial arrangement of the elements and the sequence with which they can be combined, for example, to form a higher-level drive device. FIG. 4 shows a further longitudinal section for the drive device 1 of FIG. 2, additional elements being shown in this view and the division into two sub-areas becoming clear, namely a lubricated sub-area 75 and an unlubricated sub-area 76 is highlighted by hatching and includes in particular an intermediate area between the drive shaft 7 and bearing shaft 45 as well as the area of the gear 50, the spoked wheel 31 and the radial bearing 43. In this lubricated sub-area 75, the low-friction rotational movement of the individual components with respect to one another is ensured by a lubricant promoted.

The unlubricated area 76, on the other hand, comprises the sensitive sub-areas of the drive motor 5, the braking device 8, the control device 25 and the electrical wiring that is guided within the bearing shaft 45 and is not shown in detail here. In all of these sub-areas there is no lubricant, so that the sensitive components arranged there are protected from a corresponding contamination by a lubricant.

The lubricant-tight separation of the two subregions 75 and 76 is achieved by a series of seals, which are also shown in FIG. In addition, there are additional seals to the outside for encapsulation. The main seals are the static seals 70a to 70d, the rotary seals 72a and 72b and the device of the sealed radial bearing 74a. In addition, the housing 3 is also shown in Figure 4, which effects an encapsulation to the outside.

The static seals 70a to 70e are all designed as O-ring seals. The O-ring of the first static log device 70a is located between the fixed part of the brake 8b and the housing 3 and here limits the lubricated area 75 on the outside next to the transmission 50. The O-ring the second static seal 70b is located between the disk member 22 and the first outer ring member 44a. Here it delimits the lubricated area 75 radially outward just before the radial bearing. The O-ring of the third static seal 70c is located between the first outer ring element 44a and the second outer ring element 44b. It thus forms the outer seal of the radial bearing 74. The O-ring of the fourth static seal 70d encloses a connecting line, not shown here, which leads to the outside through the flange 21a. So he seals the GE lubricated area 75 with respect to this cable bushing. The O-ring of the fifth static seal 70e is disposed within the flange 21a. It thus seals the flange connection to a next, external element to the outside. This is therefore an encapsulation against the external environment (and not an inner limitation of the lubricated area as with the other static seals 70a to 70d).

The rotary seals 72a to 72c can be designed, for example, as radial shaft sealing rings. The first rotary seal device 72a is located between the fixed part 8b of the braking device and the rotating drive element 52 of the transmission. So it seals the lubricated area of the Ge gear 50 against the unlubricated area of the Bremseinrich device 8. The second rotary seal 72b is located between the (static) second outer ring element 44b and the (rotating) second inner ring element. It thus seals the radial bearing 43 on the a2 side of this bearing and therefore delimits the lubricated area 75 at its axial end on the output side. The third rotary seal 72c is located between the rotatable output body 40 on the one hand and the fixed housing 3 and the fixed second outer ring element 44b on the other hand. Similar to the static seal 70e, this is also a seal to the outside and not an inner limitation of the lubricated area as with the other rotary seals 72a and 72b. The first radial bearing 74a is a sealed bearing, while the second radial bearing 74b is an unsealed bearing. Through the sealed bearing, the lubricated gap between tween the drive shaft 7 and the bearing shaft 45 is sealed to the motorsei term axial end al.

In summary, the static seals 70a to 70d, the rotary seals 72a and 72b and the sealed rotary bearing 74a achieve a completely lubricant-tight delimitation between the lubricated area 75 and the unlubricated area 76.

FIG. 5 shows a schematic perspective illustration of a robot arm 80 according to a further exemplary embodiment of the invention. The robot arm has seven Robotikge joints J1 to J7, which each allow a rotation about an associated axis of rotation A1 to A7. So it is a robotic arm with seven degrees of rotational freedom. The "innermost" joint J1 is connected to a base 81, which serves as a superordinate mechanical measuring device. The "outermost" joint J7 can, for example, carry a tool holder. Each of the individual joints J1 to J7 has a local mechanical mass for the respective rotary movement, which is given by the base of the respective joint.

For example, the base of the third joint J7 is denoted here by 21.

In the shown robot arm, at least one of the robotics joints J1 to J7 is provided with a drive device according to the invention. Several and in particular even all of these joints are particularly advantageously designed with drive devices according to the invention. This is explained in more detail by way of example for the third joint J3: The base 21 represents the local mechanical mass of this joint J3. This is the base of a basic holder, as was previously described in connection with FIG. Inside the Ge housing 3 of the drive device 1 for this robotic joint J3 are the other components, not visible here, such as Arranged drive motor, drive shaft, braking device, gearbox and output shaft. The end on the motor side is denoted by a1 and the end on the driven side is denoted by a2. An end cap 82 is located at the motor-side end a1. In the area of the output-side end a2, the output body (rotatable with respect to the local mechanical mass 21) merges into the base of the next robotic joint J4. The axially inner disk element belonging to the basic holder 20 is identified here by the dashed line 22. The braking device integrated between the drive motor 5 and the gear 50 brakes the rotational movement of the drive shaft already inside the articulated drive, with a rotational movement in this joint J3 being stopped immediately in the event of a power failure due to the design as a "normally closed" braking device especially advantageous when using the robot arm 80 in a collaborative work environment.

List of reference symbols

1 drive device

3 drive housing

5 drive motor

5a stator

5b rotor

7 drive shaft

8 braking device

8a brake disc

8b fixed part of the braking device

8c field coil

9 work support

20 basic holders

21 Base of the basic holder (coupling element)

21a flange

22 Disc element of the basic holder

25 Control device

31 spoked wheel

40 output body (output shaft)

41a first inner ring element

41b second inner ring element

43 radial bearings

44 Fixed element of the radial bearing

44a first outer ring element

44b second outer ring element

45 bearing shaft

48 rotary encoder on the motor side

49 rotary encoder on the output side

50 gear

51 Fixed element of the gear unit (circular spline)

52 Drive element of the transmission (wave generator)

53 Output element of the gear unit (Flex Spline)

53a Bush of the output element

54 nut ring

55 screw

70a first static seal

70b second static seal 70c third static seal

70d fourth static seal

70e fifth static seal

72a first rotary seal

72b second rotary seal

72c third rotary seal

74 radial bearings

74a first radial bearing (sealed)

74b second radial bearing (unsealed)

75 lubricated area

76 unlubricated area

80 robotic arm

81 base

82 end cap

A central axis al motor-side end a2 output-side end

B flange axis

J1 first robotic joint with axis Al

J2 second robotic joint with axis A2

J3 third robotic joint with axis A3

J4 fourth robotic joint with axis A4

J5 fifth robotic joint with axis A5

J6 sixth robotic joint with axis A6

J7 seventh robotic joint with axis A7

Claims

1. Drive device (1) for a robotic joint (J1-J7) to comprehend

- A drive motor (5) with a drive shaft (7) which is rotatable with respect to a central axis (A),

- A transmission (50) with a fixed element (51), a drive element (52) and an output element (53), the drive element (52) transmitting torque to the drive shaft (7) of the drive motor (5) is connected

- And a braking device (8) for braking the Drehbewe movement of the drive shaft (7), wherein the braking device (8) is arranged axially between the drive motor (5) and the gear (50).

2. Drive device (1) according to claim 1, wherein the braking device (8) is arranged axially adjacent to the drive motor (5).

3. Drive device (1) according to one of claims 1 or 2, in which the braking device (8) comprises an electromagnetic brake with at least one brake disc (8a) and at least one electromagnetic field coil (8c).

4. Drive device (1) according to one of the preceding claims, in which the braking device (8) is designed as a safety brake.

5. Drive device (1) according to one of the preceding claims, in which the gear (50) is designed as a Harmonie Drive Ge gear.

6. Drive device (1) according to one of the preceding claims, which has a bearing shaft (45) fixedly connected to the output element (53) of the gear unit (50) and extending in the axial direction at least over the axial areas the drive motor (5), the braking device (8) and the transmission (50) extends.

7. Drive device (1) according to claim 6, which in the motor-side end region (al) of the bearing shaft (45) has a rotary encoder (48) for determining the angular position of the drive shaft (7).

8. Drive device (1) according to one of claims 6 or 7, which in the output-side end region (a2) of the bearing shaft (45) has a rotary encoder (49) for determining the angular position of the bearing shaft (45).

9. Drive device (1) according to one of the preceding claims, which has an output body (40) which is rotatably supported by a radial bearing (43) on the output side.

10. Drive device (1) according to one of the preceding claims, which has a base holder (20) for connecting the drive device (1) to an external mechanical mass, the base holder (20) having a disc element (22) which is perpendicular to central axis (A) is aligned.

11. Drive device (1) according to claim 10, wherein the base holder (20) has a base (21) with a flange (21a) for connection to an external component,

- wherein the flange (21a) has a flange axis (B) which is perpendicular to the central axis (A) of the drive device (1).

12. Drive device (1) according to one of the preceding claims, which comprises a measuring device for measuring a torque acting within the drive device with a spoked wheel (31).

13. Drive device (1) according to one of the preceding claims, which has a lubricated sub-area (75) and an unlubricated sub-area (76), these two sub-areas (75, 76) by - at least one static seal (70a-70e),

- At least one rotary seal (72a-72c) and / or

- At least one sealed radial bearing (74a) are sealed against one another.

14. Drive device (1) according to claim 13, wherein the unlubricated partial area (76) comprises the area of a rotor (5b) and a stator (5a) of the drive motor (5) and / or the area of the braking device (8).

15. Robotic joint (J3) with a drive device (1) according to one of claims 1 to 14.