Strain wave gear, and drive device and robot arm having such a strain wave gear

Abstract

The invention relates to a strain wave gear comprising a main anti-friction bearing (18); a rigid outer ring (19) which is connected to an anti-friction bearing inner ring (18b) and has an internal toothing system (19a); a flexible transmission sleeve (20) which has an inner lateral wall (20a) and an external toothing system (20b) lying opposite the inner lateral wall (20a) and meshing with the internal toothing system (19a) of the rigid outer ring (19); a transmission sleeve flange (20c); a wave generator (21) rolling on the inner lateral wall (20a) of the flexible transmission sleeve (20) and to which a motor shaft (22a) of a drive motor (22) can be coupled, wherein the external toothing system (20b) of the flexible transmission sleeve (20) is in meshing engagement with the internal toothing system (19a) of the rigid outer ring (19); and a torque sensor (17), the sensor outer flange (17a) of which is connected to the anti-friction bearing outer ring (18a) of the main anti-friction bearing (18) and the sensor inner flange (17b) of which is connected to the flexible transmission sleeve (20). The invention also relates to a drive device (16) and to a robot arm (3) having such a strain wave gear (15).

Description

[0001] Stress wave gearbox, drive device, and robot arm with such a stress wave gearbox

[0002] The invention relates to a tension wave transmission comprising a main rolling bearing with an outer bearing ring, an inner bearing ring and rolling elements arranged between the outer bearing ring and the inner bearing ring, a rigid outer ring with internal teeth connected to the inner bearing ring, a flexible transmission bushing having an inner shell wall and an external toothing opposite the inner shell wall meshing with the internal teeth of the rigid outer ring, and a transmission bushing flange, a shaft generator rolling on the inner shell wall of the flexible transmission bushing, which has a hub with a connecting means designed for coupling the shaft generator to a motor shaft of a drive motor that can be coupled to the tension wave transmission.wherein the external teeth of the flexible transmission bushing are in meshing engagement with the internal teeth of the rigid outer ring depending on a rotational movement of the shaft generator, and a torque sensor comprising an inner sensor flange, an outer sensor flange and a torque transducer section connecting the inner sensor flange to the outer sensor flange. The invention also relates to a drive device and a robot arm with such a tension wave transmission.

[0003] EP 4 008 502 Al describes a robot joint comprising a housing, an output shaft which is at least partially housed within the housing and which is provided with a shaft section and a flange section at a first end of the shaft section, a first bearing section which is arranged in the housing and which supports a first area of ​​the flange section of the output shaft, a second bearing section which is arranged in the housing and which supports a second area of ​​the output shaft in an axial direction, and comprising a motor which is housed in the housing, wherein the second bearing section is arranged between the motor and the first bearing section along the axial direction of the output shaft.

[0004] The object of the invention is to create a tension wave drive with an improved torque sensor, in particular to create a drive device and a robot arm with such a tension wave drive in which the detection of the torque is improved.

[0005] The problem is solved by a stress wave gear, comprising:

[0006] - a main rolling bearing with a rolling bearing outer ring, a rolling bearing inner ring and rolling elements arranged between the rolling bearing outer ring and the rolling bearing inner ring,

[0007] - a rigid outer ring connected to the inner ring of the rolling bearing, with internal teeth,

[0008] - a flexible transmission bushing comprising an inner shell wall and an outer toothing opposite the inner shell wall, meshing with the internal toothing of the rigid outer ring, as well as a transmission bushing flange; - a shaft generator rolling on the inner shell wall of the flexible transmission bushing, comprising a hub with a connecting means designed for coupling the shaft generator to a motor shaft of a drive motor that can be coupled to the voltage shaft transmission;

[0009] - wherein the external teeth of the flexible transmission bushing are in meshing engagement with the internal teeth of the rigid outer ring depending on a rotational movement of the shaft generator, and

[0010] - a torque sensor comprising an inner sensor flange, an outer sensor flange and a torque transducer section connecting the inner sensor flange to the outer sensor flange, characterized in that

[0011] the outer flange of the torque sensor is connected to the outer ring of the main roller bearing, and the inner flange of the torque sensor is connected to the flexible transmission bushing.

[0012] The main rolling bearing, comprising the outer ring, the inner ring, and the rolling elements arranged between the outer and inner rings, can in particular be a crossed roller bearing. When the tension wave drive is used as a joint drive for a robot arm, the outer ring of the main rolling bearing can be connected to a first link of the robot arm, and the inner ring can be connected to a second link of the robot arm immediately adjacent in the kinematic chain of the robot arm. In this configuration, the tension wave drive forms the robot joint that rotatably connects the first link of the robot arm to the immediately adjacent second link.The outer ring of the rolling bearing can include an outer bearing flange section designed for bolting the outer ring to the first segment of the robot arm using screws from a side of the tension wave gear opposite the joint's drive motor. The inner ring of the rolling bearing can include an inner bearing flange section designed for bolting the inner ring to the second segment of the robot arm using screws, also from the side of the tension wave gear opposite the joint's drive motor. Accordingly, the tension wave gear can be bolted to both the first and second segments of the robot arm from the same side.

[0013] The transmission stage of the voltage wave gear comprises the rigid outer ring with internal teeth, the flexible transmission bushing with external teeth, and the wave generator. The rigid outer ring is also referred to as a "circular spline," the flexible transmission bushing as a "flexsp-line," and the wave generator as a "wave generator."

[0014] The flexible transmission bushing is cup-shaped and has a circular tube-shaped outer wall in the stress-free state. The outer wall of this outer wall carries the external teeth, and the shaft generator rolls against its inner wall. In this cup-shaped form, the flexible transmission bushing has a base that encompasses the transmission bushing flange.

[0015] The shaft generator has a hub that includes a connecting element by means of which the shaft generator can be coupled to a drive shaft, in particular a motor shaft of a drive motor. The connecting element can be a connecting profile, such as a splined shaft profile. However, other connecting elements can also be used. The connecting element can be a clamping connection, in particular a purely friction-fit clamping connection, such as a clamping sleeve. Alternatively, the connecting element can also be a shrink fit or a press fit, or another type of material-bonded connection to the motor shaft.

[0016] In a specific configuration, the drive torque is introduced into the tension wave gear via the shaft generator, and the translated torque is transmitted from the transmission stage via the rigid outer ring. The rigid outer ring, or a flange rigidly connected to it, thus forms an output flange or output element of the tension wave gear.

[0017] The drive motor is coupled to the side of the tension wave gear opposite the output flange. The motor shaft, or a transmission shaft connected to the motor shaft, transmits the torque generated by the drive motor through the tension wave gear to the side of the gear opposite the drive motor, where the motor shaft or transmission shaft is connected to the wave generator. Due to the specific arrangement of the torque sensor on the tension wave gear, the motor shaft, or the transmission shaft connected to the motor shaft, also transmits the torque generated by the drive motor through the torque sensor to the side of the tension wave gear opposite the drive motor, where the motor shaft or transmission shaft is connected to the wave generator.

[0018] A further advantage of such a design, in which the torque sensor is located on the same side of the tension wave gear as the drive motor, is that electrical leads running from the torque sensor to the drive electronics of the drive motor do not need to pass through the tension wave gear, and in particular not through the hollow gear shaft. In this respect, no space is required within the hollow gear shaft for routing the electrical leads of the torque sensor. In the design according to the invention, the electrical leads of the torque sensor can be routed directly from the torque sensor to the drive electronics of the drive motor on the same side of the tension wave gear, taking a short path.

[0019] The torque sensor has a circular disk shape and includes the sensor inner flange, the sensor outer flange and the torque receiver section connecting the sensor inner flange to the sensor outer flange.

[0020] The sensor's inner flange forms an inner sensor ring of smaller diameter, and the sensor's outer flange forms an outer sensor ring of larger diameter. The outer sensor flange is preferably arranged with the largest possible diameter and can, in particular, be located at the radial height of the rolling bearing's outer ring or at the radial height of the outer bearing flange section of the tension shaft drive. The sensor's inner flange, on the other hand, is preferably arranged with the smallest possible diameter and can, in particular, be located at the radial height of the transmission bushing flange of the transmission bushing. The sensor's inner flange can, in particular, be located in close proximity to the motor shaft or the transmission shaft, thus allowing it to coaxially surround the motor shaft or the transmission shaft from the outside, leaving only a small annular gap.

[0021] The torque transducer section of the torque sensor extends coaxially between the inner and outer sensor flanges, thus exhibiting the largest possible radial surface area. The torque transducer section is characterized by several connecting webs extending at least substantially or exactly radially, which connect the inner and outer sensor flanges. When a torque is applied to the torque sensor, a circumferential offset occurs between the inner and outer sensor flanges, resulting in elastic bending of the radial connecting webs. This elastic bending of the radial connecting webs, which in this respect constitute measuring elements, can be detected electrically, for example, by strain gauges attached to them.

[0022] The torque sensor can accordingly include strain gauges which are attached to specific locations on the measuring body or the connecting webs. The strain gauges detect the deformation, in particular the elongation and / or compression, of a surface area of ​​the connecting webs to which the strain gauges are attached, in particular by adhesive. The strain gauges thus detect a deformation occurring due to the torque transmitted across the connecting webs, in particular the bending of web sections of the connecting webs. Conductive tracks are arranged within the strain gauge for this purpose, which convert the deformation, in particular the elongation of the conductor tracks, into a change in electrical resistance. The electrical resistance detected at the strain gauge is then a measure of the transmitted torque.

[0023] By connecting the outer flange of the torque sensor to the outer ring of the main roller bearing and connecting the inner flange of the torque sensor to the flexible transmission bushing, a tension wave transmission with an improved torque sensor is created, in which the torque detection is improved.

[0024] Due to the special design of the torque sensor, a comparatively large radial installation space is provided, over which the torque transducer section can extend. If the radial connecting webs can extend over a relatively long radial distance, this improves the detection and evaluation of the applied torque. While the bending properties, as well as the strain and stress properties on the surfaces of the connecting webs, are generally proportional to the torque, they are only sufficiently accurate within a working range of small deformations of the connecting webs. A further advantage arises, in particular, from the fact that an applied torque can be detected with comparatively high accuracy, i.e., comparatively high resolution.An additional advantage arises from the fact that this torque sensor is very short in its axial extent, so that despite the use of a high-resolution torque sensor, the overall axial length of the tension shaft drive can be kept small.

[0025] The shaft generator can form the drive-side drive element of the voltage shaft transmission, wherein the connecting means of the shaft generator is designed for coupling the shaft generator to a motor shaft of a drive motor that can be coupled to the voltage shaft transmission, and the transmission bushing flange of the flexible transmission bushing is designed for coupling the flexible transmission bushing to a motor housing flange of the drive motor that can be coupled to the voltage shaft transmission.

[0026] The drive motor to be connected to the voltage wave gear can be coupled to a side of the voltage wave gear opposite the shaft generator and the output flange. The motor shaft, or a transmission shaft connected to the motor shaft, transmits the torque generated by the drive motor through the voltage wave gear to the side of the voltage wave gear opposite the drive motor, where the motor shaft or the transmission shaft is connected to the shaft generator in a coupled assembly.

[0027] The transmission bushing flange of the flexible transmission bushing is connected to a motor housing flange of the drive motor in the coupled assembly of the tension shaft gearbox and drive motor. Both the motor housing flange and the transmission bushing flange can be arranged, in particular, on a circumference close to the motor shaft, coaxially around the motor shaft. The transmission bushing flange can be bolted to the motor housing flange by means of third screws. The transmission bushing flange can be mounted, in particular, from the side of the tension shaft gearbox opposite the drive motor.This has the advantage that, for example, in the case of a tension wave gearbox to be mounted on a joint of a robot arm, not only can the outer ring of the rolling bearing be mounted on a first link of the robot arm using first screws from this side, but also the inner ring of the rolling bearing can be mounted on the second link of the robot arm using second screws from this side, and the transmission bushing flange can be mounted on the motor housing flange using third screws from this same side.

[0028] The torque sensor can be arranged with its sensor inner flange in an axial direction on a side of the transmission bushing flange of the flexible transmission bushing facing away from the shaft generator.

[0029] Accordingly, the torque sensor can be attached to the transmission bushing flange by means of its inner sensor flange. This attachment connects the torque sensor to the flexible transmission bushing in the area of ​​the bushing's cup base. Thus, the torque sensor does not extend on an outer circumference outside the flexible transmission bushing, but rather extends, at least substantially, in a radial direction, specifically axially behind the cup base of the flexible transmission bushing.

[0030] In the tension wave drive, the shaft generator rotates and transmits the torque to the flexible transmission sleeve at only two opposing points. Under the influence of the shaft generator, the flexible sleeve deforms accordingly and supports the torque against the rigid outer ring. The torque introduced into the tension wave drive is therefore not transmitted uniformly across the entire circumference of the flexible transmission sleeve. This can make torque measurement difficult or inaccurate if the torque sensor were located in or near the flexible circumferential wall. Therefore, it is specifically designed that the torque sensor, with its inner flange, is connected to the flexible transmission sleeve in the area of ​​the cup base, where any irregularities in the deforming circumferential wall of the flexible transmission sleeve are already compensated for or eliminated.

[0031] The torque sensor can be arranged with its sensor inner flange in the axial direction between the transmission bushing flange of the flexible transmission bushing and a motor housing flange of a drive motor that can be coupled to the voltage shaft gearbox.

[0032] In this configuration, the flexible transmission bushing is fixed to the motor housing flange by inserting the inner flange of the torque sensor. Accordingly, the inner flange of the torque sensor is also fixed to the motor housing flange.

[0033] The torque sensor can preferably be designed in a disc shape and have an outer sensor ring of larger diameter forming the sensor outer flange, an inner sensor ring of smaller diameter forming the sensor inner flange and an intermediate ring section forming the torque receiver section.

[0034] The sensor's outer flange is preferably arranged on the largest possible diameter and can, in particular, be located at the radial height of the rolling bearing's outer ring or at the radial height of the outer bearing flange section of the tension shaft drive. The sensor's inner flange, on the other hand, is preferably arranged on the smallest possible diameter and can, in particular, be located at the radial height of the transmission bushing flange of the transmission bushing. The sensor's inner flange can, in particular, be located in the immediate vicinity of the motor shaft or the transmission shaft, thus allowing this shaft to coaxially surround the motor shaft or the transmission shaft from the outside, leaving only a small annular gap.

[0035] The sensor's outer flange can have several bores evenly distributed around its circumference, lying on the same bolt circle and aligning with corresponding bores on the outer ring of the tension wave drive's rolling bearing, allowing the torque sensor to be attached to the outer ring of the tension wave drive's rolling bearing using screws. The diameter of the sensor's outer flange's bolt circle is, in particular, larger than the rolling circle of the main rolling bearing of the tension wave drive and, more specifically, larger than the diameter of the outer wall of the flexible transmission bushing of the tension wave drive.

[0036] Similarly, the sensor's inner flange can also have several bores evenly distributed around its circumference, lying on the same bolt circle and aligning with corresponding bores on the transmission bushing flange of the tension wave drive, so that the torque sensor can be attached to the transmission bushing flange of the tension wave drive by means of screws. The diameter of the bolt circle of the sensor's inner flange is, in particular, only slightly larger than the diameter of the motor shaft of the drive motor to be connected. The diameter of the bolt circle of the sensor's inner flange can, in particular, be smaller than the pitch circle of the wave generator rolling on the inner wall of the flexible transmission bushing.

[0037] The intermediate ring section can form a deformable measuring body to which deformation sensors, in particular strain gauges, are attached to detect a deformation of the intermediate ring section in order to determine or be able to determine a torque transmitted via the torque sensor.

[0038] The intermediate ring section can be completely closed. Accordingly, the intermediate ring section can be designed in the form of a membrane. Alternatively, the intermediate ring section can have spoke-like webs extending at least substantially radially, forming bending sections to which deformation sensors, in particular strain gauges, can be attached. The sensor gaps between the webs can be sealed.

[0039] The sensor gaps formed between the outer sensor ring and the intermediate ring section and / or the sensor gaps formed between the inner sensor ring and the intermediate ring section can be filled with an elastic material to seal the sensor gaps against liquid and / or gas flow from one axial side of the torque sensor to the other axial side of the torque sensor.

[0040] The elastic material can seal the sensor gaps accordingly, so that, for example, no grease or oil can escape from the voltage shaft gearbox, over the torque sensor, and towards the drive motor when the voltage shaft gearbox and torque sensor are assembled.

[0041] If separate, other sealing devices are provided for the torque sensor, which are designed and configured to prevent grease or oil from escaping from the voltage shaft transmission towards the drive motor, then the sensor gaps of the torque sensor can also remain free.

[0042] The problem is also solved by a drive device comprising a stress wave gear according to one of the described embodiments and a drive motor with a motor housing and with a motor shaft rotatably mounted in the motor housing, which is coupled to the connecting means of the shaft generator, wherein the motor housing comprises a motor housing flange to which the flexible transmission bushing is coupled.

[0043] Accordingly, the shaft generator can form the input element of the tension wave drive, and the external gearing of the tension wave drive and / or the inner ring of the roller bearing of the tension wave drive can form the output element of the tension wave drive. In this context, the flexible transmission bushing can form the support element of the tension wave drive or at least be connected to a support element of the tension wave drive. Accordingly, the flexible transmission bushing can be connected to the motor housing.

[0044] By providing a connecting element to the shaft generator, a motor shaft of the drive motor can be coupled to the shaft generator, so that a drive torque supplied via the motor shaft can be introduced into the voltage shaft transmission via the shaft generator. Within the scope of the invention, the connecting element can be understood as any type of connection that enables the coupling of the motor shaft to the shaft generator for the transmission of a drive torque, regardless of the specific design of the connecting element, such as a splined shaft profile or a clamping connection.

[0045] The motor housing includes a motor housing flange to which the flexible transmission bushing is coupled. The motor housing flange, like the sensor inner flange, can also have several bores, in particular threaded bores, evenly distributed around its circumference. These bores lie on the same bolt circle as the bores of the sensor inner flange and the bores of the flexible transmission bushing, so that the bores, especially the threaded bores, of the motor housing flange align with the corresponding bores on the transmission bushing flange of the voltage shaft drive. This allows the torque sensor to be fastened between the transmission bushing flange and the motor housing flange using screws. Similarly, the diameter of the bolt circle of the motor housing flange is only slightly larger than the diameter of the motor shaft of the drive motor to be connected.The diameter of the bolt circle of the motor housing flange can be smaller than the pitch circle of the shaft generator rolling on the inner shell wall of the flexible transmission bushing.

[0046] In the drive device, the transmission bushing flange of the flexible transmission bushing can be connected to the motor housing flange of the motor housing via the insertion of the inner sensor flange of the torque sensor. With this design, the inner sensor flange of the torque sensor is not only connected to the flexible transmission bushing but also to the motor housing flange of the motor housing. In such a configuration, the torque sensor detects the reaction torque of the drive motor as the support torque on the motor housing, which arises from the drive torque of the motor shaft. In this configuration, the total torque detected by the torque sensor represents the reaction torque to the joint torque applied at the transmission output. The joint torque is the torque acting at the joint of a robot arm to which the tension wave transmission with the torque sensor is attached.In this configuration, the torque sensor does not directly measure the output torque at the gearbox output, but rather its reaction torque.

[0047] The torque sensor may be covered on its side facing the motor housing by a sealing wall, which is designed to seal a gearbox chamber of the tension shaft transmission in order to prevent fluid leakage and / or gas leakage from the gearbox chamber towards the motor housing.

[0048] The sealing wall can prevent fluid and / or gas leakage from the gearbox chamber towards the engine housing, thus replacing a separate elastic material on the torque sensor for sealing sensor gaps.

[0049] Alternatively, to increase sealing reliability, a sealing wall can be provided in addition to elastic material on the torque sensor to seal sensor gaps.

[0050] The sealing wall can be arranged in the axial direction either on the side of the torque sensor facing the voltage wave gear or the sealing wall can be arranged in the axial direction on the side of the torque sensor facing the drive motor.

[0051] Specifically, if the sealing wall is arranged axially on the side of the torque sensor facing the drive motor, it can be positioned axially between the torque sensor and the motor housing flange. The sealing wall, separate from the torque sensor, can either be attached to the outer bearing race of the tension shaft drive and have a sealing edge that seals against the motor housing flange or the motor housing, or it can be attached to the motor housing flange or the motor housing and have a sealing edge that seals against the outer bearing race of the tension shaft drive.

[0052] The motor housing flange can have an axially extending shoulder which holds an end face of the motor housing flange at radial height of the torque receiver section of the torque sensor at such a distance from the torque receiver section of the torque sensor that a space is formed for receiving a sensor electronics board.

[0053] Accordingly, a sensor electronics board can be positioned between the torque sensor's transducer section and the motor housing flange. This close spatial positioning of the sensor electronics board and the torque sensor results in a very small distance to be bridged when electrical leads, for example, from the torque sensor's strain gauges to the sensor electronics board, need to be routed. By positioning the sensor electronics board between the torque sensor and the motor housing flange, a very compact design for the drive unit can be achieved. The shortest possible electrical leads also contribute to improved data transmission.

[0054] If a separate sealing wall is provided for the torque sensor, the sensor electronics board can preferably be arranged between the sealing wall and the motor housing flange. Accordingly, the sealing wall also protects the sensor electronics board from coming into contact with oil or grease from the voltage shaft drive.

[0055] The problem is further solved by a robot arm with several links and several joints, wherein each joint connects two immediately adjacent links in the kinematic chain of the robot arm in an adjustable manner relative to each other, with automatically controllable drives, each of which is designed to move one of the joints, so that by automatically controlled movement of the joints by means of the drives the links of the robot arm can be adjusted into a desired joint configuration, characterized in that at least one of the drives is designed as a drive device according to one of the described embodiments.wherein the rolling bearing outer ring of the tension shaft drive of the drive device is connected to one adjacent member of the joint driven by the drive device, and the rigid outer ring of the tension shaft drive of the drive device, connected to the rolling bearing inner ring, is connected to the other adjacent member of the joint driven by the drive device.

[0056] The outer flange of the torque sensor is connected to the adjacent link of the joint driven by the drive device. This adjacent link of the robot arm, to which the outer flange of the torque sensor is attached, can be the link upstream of the joint containing the torque sensor in the kinematic chain of robot arm links running from the proximal base frame to the distal tool flange of the robot arm.

[0057] Specific embodiments of the invention are explained in more detail in the following description with reference to the accompanying figures. Specific features of these exemplary embodiments, regardless of the specific context in which they are mentioned, may also represent advantageous features of alternative embodiments of the invention, either individually or in further combinations.

[0058] They show:

[0059] Fig. 1 shows a perspective view of a first embodiment of a robot, in particular an industrial robot, comprising a robot arm with limbs, joints and drive devices, as well as a control device designed and configured to automatically control the drive devices in order to move the robot arm.

[0060] Fig. 2 shows a perspective view of a second embodiment of a robot, in particular a lightweight robot designed for human-robot collaboration, comprising a robot arm with limbs, joints and drive devices, and a control device designed and configured to automatically control the drive devices to move the robot arm.

[0061] Fig. 3 shows a schematic sectional view of an exemplary first embodiment of a voltage wave drive according to the invention with a torque sensor according to the invention, and

[0062] Fig. 4 shows a schematic sectional view of an exemplary second embodiment of a voltage wave drive according to the invention with a torque sensor according to the invention, which additionally has a separate sealing wall.

[0063] Fig. 1 shows an exemplary robot 1 of the type of industrial robot with a control device 2 and a robot arm 3. The robot arm 3 has a base frame 5 as its first element G1, on which a carousel 7 as its second element G2 is rotatably mounted about a first vertical axis A1 and driven by a first drive motor M1. The axes A1-A6 of the robot arm 3 can also be referred to as joints L1-L6 of the robot arm 3. A rocker arm 8 as its third element G3 is pivotably mounted on the carousel 7 about a second horizontal axis A2 and driven by a second drive motor M2. The rocker arm 8 carries a boom 9, which is pivotably mounted about a third horizontal axis A3 and driven by a third drive motor M3.On the arm extension 9, whose base arm 10 forms a fourth link G4, a fourth axis A4 is provided, which runs in the longitudinal extension of the arm extension 9 and drives a front arm 11 via a fourth drive motor (not shown), which forms a fifth link G5.

[0064] From the forearm 11, a first leg 12a and a second leg 12b extend forward in a fork-like shape. The two legs 12a, 12b support a bearing for a hand 13, which forms a sixth link G6. The bearing defines a fifth axis A5 of the robot arm 3, about which the hand 13 can be pivoted by means of a fifth drive motor (not shown). Additionally, the hand 13 has a sixth axis A6 to enable a sixth drive motor (not shown) to drive a mounting flange 14, which forms a seventh link G7, in a rotatable manner. Each axis A5 to A6 is associated with a joint LI to L6, which, in the illustrated embodiment, connect the links G6 to G7 in the manner of a serial kinematic system of a kick-arm robot.

[0065] One or more of the joints LI to L6 of the robot arm 3 can have a tension wave drive 15 according to the invention.

[0066] Fig. 2 shows a modified design of a robot arm 3 in the form of a lightweight robot 3a with a total of six or seven axes. This lightweight robot 3a is particularly well suited for human-robot collaboration. The lightweight robot 3a can be operated in force / torque-controlled mode by means of the control device 2, in particular in compliance control mode. This lightweight robot 3a has several links G and joints L that adjust the links G relative to each other, each of which is designed as a rotary joint. In this respect, the joint L connects a first link G1 of the robot arm 3 to an immediately adjacent second link G2 of the robot arm 3 in a rotatable manner, wherein the corresponding rotary joint can each have a tension wave drive 15 or a drive device 16 according to the invention in one of the described embodiments.

[0067] In the robot arm 3 with the multiple links G and multiple joints L, each joint L connects two immediately adjacent links G in the kinematic chain of the robot arm 3 in an adjustable manner, by means of automatically controlled drive devices 16, each of which is designed to move each of the joints L, so that by automatically controlled movement of the joints L by means of the drive devices 16 the links G of the robot arm 3 can be adjusted into a desired joint configuration.

[0068] At least one of the drive devices 16, in particular all drive devices 16 of all joints L, are designed as a drive device 16 according to one of the described embodiments, wherein the rolling bearing outer ring 18a of the tension wave drive 15 of the drive device 16 is connected to one adjacent member G of the joint L driven by the drive device 16 and the rigid outer ring 19 of the tension wave drive 15 of the drive device 16, connected to the rolling bearing inner ring 18b, is connected to the other adjacent member G of the joint L driven by the drive device 16.

[0069] Figures 3 and 4 each show a drive device 16, in particular the tension wave gear 15 and a torque sensor 17 in a half-section.

[0070] The tension wave gear 15 has a main rolling bearing 18 with a rolling bearing outer ring 18a, a rolling bearing inner ring 18b and rolling elements 18c arranged between the rolling bearing outer ring 18a and the rolling bearing inner ring 18b.

[0071] The tension wave gear 15 also has a rigid outer ring 19 connected to the roller bearing inner ring 18b with an internal toothing 19a .

[0072] A flexible transmission bushing 20 of the tension wave transmission 15 has an inner shell wall 20a and an outer toothing 20b opposite the inner shell wall 20a, meshing with the internal toothing 19a of the rigid outer ring 19, as well as a transmission bushing flange 20c.

[0073] The tension wave gear 15 also has a shaft generator 21 rolling on the inner shell wall 20a of the flexible transmission bushing 20, which has a hub 21a with a connecting means designed for coupling the shaft generator 21 to a motor shaft 22a of a drive motor 22 coupled to the tension wave gear 15.

[0074] The external teeth 20b of the flexible transmission bushing 20 mesh with the internal teeth 19a of the rigid outer ring 19 depending on a rotational movement of the shaft generator 21. The tension shaft transmission 15 also includes the torque sensor 17, which has an inner sensor flange 17b, an outer sensor flange 17a and a torque receiver section 17c connecting the inner sensor flange 17b to the outer sensor flange 17a.

[0075] The outer sensor flange 17a of the torque sensor 17 is connected to the outer rolling bearing ring 18a of the main rolling bearing 18 and the inner sensor flange 17b of the torque sensor 17 is connected to the flexible transmission bushing 20.

[0076] In the present embodiments, the shaft generator 21 forms the drive-side drive element of the tension wave gear 15, wherein the connecting element of the shaft generator 21 is designed for coupling the shaft generator 21 to the motor shaft 22a of the drive motor 22 coupled to the tension wave gear 15. The transmission bushing flange 20c of the flexible transmission bushing 20 is designed for coupling the flexible transmission bushing 20 to a motor housing flange 22b of the drive motor 22 that can be coupled to the tension wave gear 15.

[0077] The sensor outer flange 17a can have several bores 23 evenly distributed around its circumference, which lie on the same pitch circle and can align with corresponding bores 24 on the outer bearing ring 18a of the tension wave drive 15, so that the torque sensor 17 can be attached to the outer bearing ring 18a of the tension wave drive 15 by means of screws (not shown). The diameter of the pitch circle of the sensor outer flange 17a is, in particular, larger than the pitch circle of the main bearing 18 of the tension wave drive 15 and, in particular, larger than the diameter of the inner wall 20a of the flexible transmission bushing 20 of the tension wave drive 15.

[0078] Similarly, the sensor inner flange 17b can also have several bores 25 evenly distributed around its circumference, which lie on the same bolt circle and can align with corresponding bores 26 on the transmission bushing flange of the tension wave gear 15, so that the torque sensor 17 can be attached to the transmission bushing flange 20c of the tension wave gear 15 by means of screws 27. The diameter of the bolt circle of the sensor inner flange 17b is, in particular, only slightly larger than the diameter of the motor shaft 22a of the connected drive motor 22. The diameter of the bolt circle of the sensor inner flange 17b can, in particular, be smaller than the pitch circle of the shaft generator 21 rolling on the inner shell wall 20a of the flexible transmission bushing 20.

[0079] The sensor gaps formed between the outer sensor ring and the intermediate ring section and / or between the inner sensor ring and the intermediate ring section can be filled with an elastic material to seal the sensor gaps against liquid and / or gas flow from one axial side of the torque sensor 17 to the other axial side. In the second embodiment according to Fig. 4, such filling of the sensor gaps with an elastic material is not necessary, since a separate sealing wall 28 is provided there.

[0080] The sealing wall 28 can prevent fluid leakage and / or gas leakage from the gearbox chamber towards the motor housing 22c or towards the motor housing flange 22b and can thus directly replace a separate elastic material on the torque sensor 17 for sealing sensor gaps.

[0081] The sealing wall 28 can be arranged in the axial direction either on the side of the torque sensor 17 facing the tension wave gear 15 or the sealing wall 28 can be arranged in the axial direction on the side of the torque sensor 17 facing the drive motor 22, as shown in Fig. 4.

[0082] Specifically, if the sealing wall 28 is arranged axially on the side of the torque sensor 17 facing the drive motor 22, as shown, the sealing wall 28 can thus be arranged axially between the torque sensor 17 and the motor housing flange 22b. The sealing wall 28, which is separate from the torque sensor 17, can either be attached to the outer bearing ring 18a of the tension shaft drive 15 or, as shown in Fig. 4, to the outer sensor ring and have a sealing edge sealing against the motor housing flange 22b, or it can be attached to the motor housing flange 22b or to the motor housing 22c and have a sealing edge sealing against the outer bearing ring 18a of the tension shaft drive 15 or against the outer sensor ring.

[0083] The torque sensor 17 can be arranged with its sensor inner flange 17b in the axial direction on a side of the transmission bushing flange 20c of the flexible transmission bushing 20 facing away from the shaft generator 21, as shown in Fig. 3 and Fig. 4.

[0084] The torque sensor 17 is accordingly arranged with its sensor inner flange 17b in the axial direction between the transmission bushing flange 20c of the flexible transmission bushing 20 and the motor housing flange 22b of the drive motor 22 coupled to the tension shaft gearbox 15.

[0085] The torque sensor 17 is designed in a disc shape and has an outer sensor ring of larger diameter forming the sensor outer flange 17a, an inner sensor ring of smaller diameter forming the sensor inner flange 17b and an intermediate ring section forming the torque receiver section 17c.

[0086] Figures 3 and 4 thus show a drive device 16 comprising the voltage wave gear 15 and the drive motor 22 with the motor housing 22c and with the motor shaft 22a rotatably mounted in the motor housing 22c, which is coupled to the connecting means of the shaft generator 21, wherein the motor housing 22c comprises the motor housing flange 22b to which the flexible transmission bushing 20 is coupled.

[0087] The transmission bushing flange 20c of the flexible transmission bushing 20 is connected to the motor housing flange 22b of the motor housing 22c by means of the sensor inner flange 17b of the torque sensor 17.

[0088] In the second embodiment according to Fig. 4, the torque sensor 17 is covered on its side facing the motor housing 22c by the sealing wall 28, which is designed to seal the gearbox compartment of the tension shaft drive 15 in order to prevent fluid and / or gas leakage from the gearbox compartment towards the motor housing 22c or towards the motor housing flange 22b. As shown, the motor housing flange 22b has an axially extending shoulder 29 which holds an end face of the motor housing flange 22b at the radial height of the torque sensor section 17c of the torque sensor 17 at such a distance from the torque sensor section 17c of the torque sensor 17 that a space is formed for receiving a sensor electronics board 30.

Claims

Patent claims 1. Tension wave gear ( 15) , comprising: - a main rolling bearing ( 18 ) with a rolling bearing outer ring ( 18a ), a rolling bearing inner ring ( 18b ) and rolling elements ( 18c) arranged between the rolling bearing outer ring ( 18a ) and the rolling bearing inner ring ( 18b ), - a rigid outer ring (19) connected to the rolling bearing inner ring (18b) with an internal toothing (19a) , - a flexible transmission bushing (20) comprising an inner shell wall (20a) and an outer toothing (20b) opposite the inner shell wall (20a) meshing with the internal toothing (19a) of the rigid outer ring (19) as well as a transmission bushing flange (20c), - a shaft generator (21) rolling on the inner shell wall (20a) of the flexible transmission bushing (20), which has a hub (21a) with a connecting means designed for coupling the shaft generator (21) to a motor shaft (22a) of a drive motor (22) that can be coupled to the voltage shaft transmission (15), - wherein the external toothing (20b) of the flexible transmission bushing (20) is in meshing engagement with the internal toothing (19a) of the rigid outer ring (19) depending on a rotational movement of the shaft generator (21), and - a torque sensor (17) comprising an inner sensor flange (17b), an outer sensor flange (17a) and a torque transducer section (17c) connecting the inner sensor flange (17b) to the outer sensor flange (17a), characterized in that the sensor outer flange (17a) of the torque sensor (17) is connected to the rolling bearing outer ring (18a) of the main rolling bearing (18) and the sensor inner flange (17b) of the torque sensor (17) is connected to the flexible transmission bushing (20).

2. Tension wave transmission (15) according to claim 1, characterized in that the shaft generator (21) forms the drive-side drive element of the tension wave transmission (15), wherein the connecting means of the shaft generator (21) is designed for coupling the shaft generator (21) to a motor shaft (22a) of a drive motor (22) that can be coupled to the tension wave transmission (15) and the transmission bushing flange (20c) of the flexible transmission bushing (20) is designed for coupling the flexible transmission bushing (20) to a motor housing flange (22b) of the drive motor (22) that can be coupled to the tension wave transmission (15).

3. A tension wave transmission (15) according to claim 1 or 2, characterized in that the torque sensor (17) with its sensor inner flange (17b) is arranged axially on a side of the transmission bushing flange (20c) of the flexible transmission bushing (20) facing away from the wave generator (21).

4. A tension wave transmission (15) according to claim 3, characterized in that the torque sensor (17) with its sensor inner flange (17b) is arranged axially between the transmission bushing flange (20c) of the flexible transmission bushing (20) and a motor housing flange (22b) of a drive motor (22) that can be coupled to the tension wave transmission (15).

5. Voltage wave gear ( 15) according to one of claims 1 to 4, characterized in that the torque sensor ( 17 ) is designed in a disc shape and has an outer sensor ring of larger diameter forming the sensor outer flange ( 17a ), an inner sensor ring of smaller diameter forming the sensor inner flange ( 17b ) and an intermediate ring section forming the torque receiver section ( 17c ).

6. Tension wave gear ( 15) according to claim 5, characterized in that the intermediate ring section forms a deformable measuring body on which deformation sensors, in particular strain gauges, are attached to detect a deformation of the intermediate ring section in order to be able to determine a torque transmitted via the torque sensor ( 17).

7. Drive device ( 16) comprising a voltage wave gear ( 15) according to one of claims 1 to 6 and a drive motor (22 ) with a motor housing (22c) and with a motor shaft (22a) rotatably mounted in the motor housing (22c) which is coupled to the connecting means of the shaft generator (21 ), wherein the motor housing (22c) comprises a motor housing flange (22b) to which the flexible transmission bushing (20) is coupled.

8. Drive device ( 16) according to claim 7, characterized in that the transmission bushing flange (20c) of the flexible transmission bushing (20) is connected to the motor housing flange (22b) of the motor housing (22c) by means of the sensor inner flange ( 17b) of the torque sensor ( 17 ).

9. Drive device ( 16) according to claim 7 or 8, characterized in that the motor housing flange (22b) has an axially extending shoulder (29) which holds an end face of the motor housing flange (22a) at radial height of the torque receiver section ( 17c) of the torque sensor ( 17 ) at such a distance from the torque receiver section ( 17c) of the torque sensor ( 17) that a space is formed for receiving a sensor electronics board (30).

10. Robot arm (3) with several links (G) and several joints (L), wherein each joint (L) adjustably connects two links (G) directly adjacent to each other in the kinematic chain of the robot arm (3), with automatically controllable drives, each of which is configured to move each of the joints (L) of the joints (L), such that the links (G) of the robot arm (3) can be adjusted into a desired joint configuration by automatically controlled movement of the joints (L) by means of the drives, characterized in that at least one of the drives is configured as a drive device (16) according to one of claims 7 to 9,wherein the rolling bearing outer ring (18a) of the tension shaft drive (15) of the drive device (16) is connected to one adjacent link (G) of the joint (L) driven by the drive device (16) and the rigid outer ring (19) of the tension shaft drive (15) of the drive device (16) connected to the rolling bearing inner ring (18b) is connected to the other adjacent link (G) of the joint (L) driven by the drive device (16).

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