Strain wave gear mechanism

Abstract

The invention relates to a strain wave gear mechanism comprising: a wave generator which is rotatably mounted relative to a flexspline about an axis of rotation; and a gear which meshes with the flexspline. The problem is solved by a strain wave gear mechanism which is characterised by: at least one deformation measurement sensor which measures a deformation, in particular a radial deformation, of the gear and / or of a transmission component which is connected to the gear or to the flexspline, said deformation being caused by the shape of the wave generator; and an evaluation device which receives measurement signals from the at least one deformation measurement sensor and, on the basis of the measurement signals, determines the rotational position and / or the rotational speed and / or the direction of rotation of the wave generator and / or of a transmission element rotating in accordance with the reduction ratio of the strain wave gear mechanism, in particular of the flexspline, in particular relative to the gear or relative to the flexspline.

Description

[0001] tension shaft gear

[0002] The invention relates to a stress wave transmission with a wave generator which is mounted so as to be rotatable about a rotation axis relative to a flexspline, and with a gear which meshes with the flexspline.

[0003] A stress wave transmission usually has a rigid, circular-section, internally toothed gear, called a circular spline, and a flexible, externally toothed gear, called a flexspline, which is arranged in the space surrounded by a rigid, internally toothed gear. A usually oval wave generator is rotatably arranged within the flexspline, the outer circumference of which has a bearing seat for a radially flexible rolling bearing. The wave generator is in contact with the radially flexible, externally toothed gear via the radially flexible rolling bearing. The radially flexible rolling bearing enables the wave generator to rotate relative to the radially flexible, externally toothed gear. The wave generator bends the rolling bearing and the flexspline into an oval shape in order to mesh the teeth of the circular spline and the flexspline along the vertical axis of the oval wave generator.

[0004] The flexspline has fewer teeth than the circular spline. When the wave generator rotates, the outer side of the flexspline rolls against the inner side of the circular spline, with the teeth of the flexspline circumferentially engaging and disengaging from the teeth of the circular spline on opposite sides. Due to the difference in the number of teeth, the flexspline rotates relative to the circular spline when the wave generator rotates and the flexspline is held in place, for example, relative to the gearbox housing. The wave generator is usually elliptical. However, any shape deviating from the circular shape is possible, resulting in the described engagement of the teeth of the flexible, externally toothed gear with the teeth of the rigid, internally toothed gear.It is also possible to design the wave generator in such a way that the teeth of the flexspline engage with the teeth of the circular spline at three or more points.

[0005] In the ring design of a stress wave gear, two internally toothed, rigid ring gears (circular spline and dynamic spline) with different numbers of teeth are present. Their teeth mesh with the external teeth of the radially flexible, externally toothed sleeve (flexspline). One of the internally toothed ring gears has the same number of teeth as the flexspline, while the other internally toothed ring gear has more teeth than the flexspline. Stress wave gears are known that offer a wider range of functions due to the ability to output an actual torque.

[0006] WO 2010 142318 A1 discloses a device for measuring the torque transmitted to an output shaft of a stress wave transmission. The device comprises a housing, a circular spline mounted in the housing, and a flex spline mounted on the output shaft. The device also includes sensors arranged between the circular spline and the housing for measuring forces, as well as a computing unit that receives measurement signals from the sensors and calculates the transmitted torque based on them.

[0007] DE 103 21 210 A1 also discloses a method for measuring torque in a stress wave transmission. The method provides for amplifying the gain of a torque output signal from each of several sets of strain sensors attached to the diaphragm of a flexible external gear before the output signals are then combined to form a measurement signal. Adjusting the gain of each strain sensor output signal enables compensation for rotational ripple contained in the output signal, with compensation down to nth-order ripple components possible with the aid of at least (2n + 1) rotation sensors.

[0008] A torque measuring device for a stress wave transmission is also known from DE 10 2018 124 685 A1. The torque measuring device comprises a plurality of strain sensors coupled to the flexspline and configured to detect stretching and / or compressive deformations of the flexspline and provide them as measurement signals. The torque measuring device also comprises a readout circuit coupled to the plurality of strain sensors and configured to preprocess the measurement signals and transmit them to a computer. The computer includes a neural network and is configured to calculate a torque acting on the flexspline from the preprocessed measurement signals using machine learning.

[0009] European patent application EP 4 257848 A1 discloses a transmission system comprising a torque support element and a three-shaft transmission. The three-shaft transmission has at least one, in particular annular, gear. The gear is designed as a flange or has a flange. The gear is secured to the torque support element by means of an elastically deformable coupling component having a counterflange that is rotationally connected to the flange.From the German patent DE 10 2020 107 674 B3 a stress wave transmission device is known which comprises a stress wave transmission with a first gearwheel which functions as a circular spline, a second gearwheel which functions as a flex spline, a wave generator and a spatially fixed component, wherein a coding embodiment is arranged on one of the gearwheels or the wave generator and at least one sensor is provided on the spatially fixed component which is designed to detect the coding embodiment in a contactless manner.

[0010] It is the object of the present invention to provide a stress wave transmission which offers an even further increased range of functions.

[0011] The object is achieved by a stress wave transmission which is characterized by a. at least one deformation measuring sensor which measures a deformation of the gearwheel and / or of a transmission component connected to the gearwheel or to the flexspline caused by the shape of the wave generator, in particular a radial deformation, and by b. an evaluation device which receives measurement signals from the at least one deformation measuring sensor and which determines from the measurement signals the rotational position and / or the rotational speed and / or the direction of rotation of the wave generator and / or of a transmission element rotating with the reduction ratio of the stress wave transmission, in particular relative to the gearwheel or relative to the flexspline.

[0012] The invention has the very special advantage that the rotational position and / or speed and / or direction of rotation determined from the measurement signals can be used, for example, to control or regulate a higher-level system, for example a robot or a robot joint or a vehicle component, into which the stress wave transmission according to the invention is installed. The higher-level system can be, for example, a robot, a robot joint or a vehicle component. In particular, the invention has the very special advantage that the rotational position and / or speed and / or direction of rotation determined from the measurement signals can be used, for example, to control or regulate a drive motor to which the stress wave transmission according to the invention is operatively connected, in particular downstream of it in terms of drive technology.

[0013] The gear element rotating with the reduction ratio of the stress wave gear can, for example, be the flexspline if the gear is fixed to the gear housing and the wave generator acts as the gear drive. The gear element rotating with the reduction ratio of the stress wave gear can, for example, be the gear if the flexspline is fixed to the gear housing and the wave generator acts as the gear drive. The gear element rotating with the reduction ratio of the stress wave gear can, for example, be another gear meshing with the flexspline if the stress wave gear is designed as a ring gear and the wave generator acts as the gear drive. In the latter case, for example, the gear can function as a dynamic spline and the other gear as a circular spline, or vice versa.

[0014] Even if the gear or the gear component connected to the gear or flexspline can be considered stiff, particularly with regard to their primary function within the stress wave transmission, small elastic deformations of the gear or gear component occur due to the periodic loading from the rotating wave generator. Although these elastic deformations are small, they exhibit characteristic patterns that arise from the interaction between the wave generator, flexspline, and gear. Preferably, the gear and gear component are designed to be just as stiff as in the stress wave transmissions known from the prior art. At the very least, the gear and gear component are designed to be so stiff that these minor elastic deformations have no influence, or at least no significant influence, on the primary function of the gear and gear component within the stress wave transmission.

[0015] It was recognized that these small elastic deformations can be measured, and information about the rotational position, speed, or direction of rotation of the shaft generator or the gear component can be derived from them. For example, it can advantageously be provided that an evaluation device performs a Fourier analysis of the measurement signals in order to identify periodic patterns in the deformations and take these into account in the evaluation. From the measurement signal, a kinematic variable, namely the speed, rotational position, and / or direction of rotation, and a dynamic variable, namely the torque, can be derived. These are essential parameters of a precision gear. The concept therefore uses an indirect measurement technique in which structural reactions to the excitation by the rotating shaft generator are analyzed.

[0016] The gear component can advantageously be attached to the gear or to the flexspline. In particular, the gear component can be attached to the gear or to the flexspline in a force-fitting, form-fitting, and / or material-fitting manner. For example, the gear component can be attached to the gear or to the flexspline by means of one or more screw connections. In an advantageous embodiment, the flexspline has external teeth. In this embodiment, the gear is an internally toothed ring gear. In particular, the gear can be a circular spline or a dynamic spline of the stress wave transmission.

[0017] Another design is also possible in the form of a so-called external rotor, in which the flexspline has an internal toothing, while the circular spline has an external toothing.

[0018] The connection between the gear component and the gear or the flexspline is preferably rigid and / or torsionally rigid. It can be a force-locking, form-locking, and / or material-locking connection. Alternatively, the connection can also be realized by manufacturing the connected parts as a single piece.

[0019] The transmission component connected to the gear or the flexspline can, for example, be a transmission housing.

[0020] In a special design that enables a compact and robust construction, the transmission component is part of a bearing. In particular, the transmission component can be an inner or outer ring of a rolling bearing.

[0021] Alternatively, the transmission component can be a flange.

[0022] In particular, the transmission component can be a flange connected to the flexspline. For example, the transmission component can be a flange arranged at the bottom of a cup-shaped flexspline or at the brim of a hat-shaped flexspline.

[0023] In particular, the transmission component can be a flange connected to the gear, in particular designed as a circular spline or as a dynamic spline.

[0024] In a particularly advantageous embodiment, the evaluation device records the measurement signals as a function of time. Such an embodiment makes it possible, in particular, to draw conclusions about the rotational speed of the shaft generator and / or the rotating transmission element relative to the gear from the continuous periodic change in the deformation of the gear and / or the transmission component connected to the gear or the flexspline caused by the shape of the wave generator.

[0025] The deformation sensor can, for example, comprise at least one strain gauge. However, alternatively or in addition to at least one strain gauge, other measuring means, such as a piezo-based length measuring sensor or a shear force sensor, can also be present to detect the deformation.

[0026] In a particularly precise and reliable design, the deformation measurement sensor has at least one deformation section whose shape continuously and repeatedly changes during rotation of the wave generator, particularly when the stress wave gear is unloaded. The deformation section can be formed, for example, by a section of the gear and / or the gear component connected to the gear or to the flexspline.

[0027] To detect the change in the shape of the deformation section, a measuring sensor, for example, at least one strain gauge, can be glued to the deformation section. However, alternatively or in addition to the at least one strain gauge, other measuring sensors, for example, a piezo-based length measuring sensor, can also be attached to the deformation section to detect the deformation.

[0028] In an advantageous embodiment, the deformation section is a compression section that experiences a continuously changing compressive load during rotation of the wave generator, especially when the stress wave gear is unloaded. In particular, the deformation section can advantageously be designed and arranged such that it experiences exclusively compressive loads during rotation of the wave generator. Such a design operates with particular precision.

[0029] It can also be provided that the deformation section is a tensile section that experiences a continuously changing tensile load during rotation of the wave generator, especially when the stress wave gear is unloaded. In particular, the deformation section can advantageously be designed and arranged such that it experiences only tensile loads during rotation of the wave generator. Such a design operates with particular precision.

[0030] The stress wave transmission preferably has a plurality of deformation sections. It can advantageously be provided that some of the deformation sections are compression sections and others are tension sections.

[0031] In a special embodiment, the deformation section is continuously subjected to alternating compressive and tensile loads during rotation of the wave generator, particularly when the stress wave gear is unloaded. In another embodiment, the deformation section is designed and arranged such that it experiences continuously alternating bending and / or shear loads during rotation of the wave generator, particularly when the stress wave gear is unloaded.

[0032] In a particularly precise design, a first group of deformation measuring sensors and a second group of deformation measuring sensors are provided. For example, a total of six deformation measuring sensors can be provided, with the first, third, and fifth deformation measuring sensors being assigned to the first group of deformation measuring sensors, while the second, fourth, and sixth deformation measuring sensors are assigned to the second group of deformation measuring sensors, viewed in the direction of rotation.The evaluation device processes the measurement signals of the first group of deformation measuring sensors and the second group of deformation measuring sensors separately from one another, wherein a comparison of the results is subsequently carried out for plausibility and / or a final result for the rotational position and / or the speed and / or the direction of rotation of the wave generator and / or the rotating gear element relative to the gear is obtained by calculating the results.

[0033] In a particularly advantageous embodiment, the evaluation device determines the current rotational position of the wave generator and / or the rotating gear element starting from an initial rotational position, taking into account a measured temporal profile of the measurement signals. In particular, it can advantageously be provided that the evaluation device determines the current rotational position of the wave generator and / or the rotating gear element starting from an initial rotational position, taking into account a measured temporal profile of the measurement signals and the gear reduction. Such an embodiment is particularly reliable.

[0034] The deformation sensor can be arranged, for example, on the gear or on the transmission component. In particular, the deformation sensor can comprise at least one strain gauge that is bonded to the gear or the transmission component.

[0035] In a particularly advantageous embodiment, the deformation measuring sensor is formed on a connector or part of a connector which connects two gear component elements of the gearwheel to one another, in particular elastically movable, or which connects two gear component elements of the gear component to one another, in particular elastically movable, or which connects the gearwheel to the gear component, in particular elastically movable, or which connects the gear component to another gear component, in particular elastically movable, or which connects the gear component to the flexspline, in particular elastically movable.In particular, a plurality of connectors, which are designed as deformation measuring sensors or are each part of a deformation measuring sensor, can be present, each of which connects two gear component elements of the gearwheel, in particular elastically movable, to one another, or which connects two gear component elements of the gear component, in particular elastically movable, to one another, or which connects the gearwheel to the gear component, in particular elastically movable, or which connects the gear component to another gear component, in particular elastically movable, or which connects the gear component to the flexspline, in particular elastically movable.

[0036] The connector can have a first fastening section and a second fastening section for fastening to the aforementioned components. The fastening can have a force-fitting, form-fitting, and / or material-fitting connection. In a particularly advantageous embodiment, the fastening of the connector is designed to be non-destructively removable. Such a design is particularly flexible in use, especially with regard to later conversion of the stress wave gear.

[0037] In general, it can advantageously be provided that the connector has at least one pressure section that is subjected to pressure, in particular exclusively to pressure. Such a design makes it possible, for example, to measure the pressure forces and, from the measured pressure forces, to infer the rotational position and / or the speed and / or the direction of rotation of the wave generator and / or the rotating gear element relative to the gear. The pressure section can in particular be designed as a pressure rod. The pressure rod, in turn, can be formed by a leg of the connector, in particular one of several legs of the connector.

[0038] Likewise, quite generally, it can advantageously be provided that the connector has at least one tensile section that is subjected to tensile stress, in particular exclusively tensile stress. Such a design makes it possible, for example, to measure the tensile forces and, from the measured tensile forces, to infer the rotational position and / or the rotational speed and / or the direction of rotation of the wave generator and / or the rotating gear element relative to the gear. The tensile section can, in particular, be designed as a tensile rod. The tensile rod, in turn, can be formed by a leg of the connector, in particular one of several legs of the connector.

[0039] In a particularly advantageous embodiment, the connector has at least one compression section and at least one tension section. Such a design makes it possible, for example, to measure the compression and tension forces simultaneously. Such a measurement is particularly accurate and robust against disturbances.

[0040] In particular, it can be provided that a section of the connector forms the pressure section in one direction of rotation of a shaft of the transmission, for example the drive shaft of the transmission, and the tension section in an opposite direction of rotation of the shaft.

[0041] The connector can advantageously have a U-shaped cross-section. Such a design allows, for example, one of the legs of the U-shaped connector in cross-section to be inserted, in particular axially or radially, into a first plug-in recess of the respective component for the purpose of fastening, in particular in a clamping and / or precise manner, and the other leg of the U-shaped connector in cross-section to be inserted, in particular axially or radially, into a second plug-in recess of the respective component for the purpose of fastening, in particular in a clamping and / or precise manner.

[0042] The connector can advantageously have an S-shaped cross-section, an X-shaped cross-section, or a V-shaped cross-section. For example, such a design can include axial plug-in pins that are inserted into axial plug-in recesses of the respective component for fastening purposes.

[0043] In a particularly advantageous embodiment, the connector is designed such that, depending on the sign of the torque, at least one leg of the connector is the tensile section and at least one other leg of the connector is the compressive section. Such a design is particularly precise and allows accurate measurement if the legs function as part of a deformation sensor, wherein, for example, at least one strain gauge can be glued to each of the individual legs. However, alternatively or in addition to at least one strain gauge, other measuring means, such as a piezo-based length measuring sensor, can also be present to detect the deformation of the connector.

[0044] The connector can generally advantageously have at least two legs, in particular one of the legs forming the compression section and the other the tension section.

[0045] As already mentioned, the stress wave transmission according to the invention preferably comprises a plurality of deformation measuring sensors. The deformation measuring sensors can be arranged distributed in the circumferential direction. In particular, the deformation measuring sensors can be arranged such that the distances between immediately adjacent deformation measuring sensors are equal. However, a particularly advantageous embodiment is one in which the deformation measuring sensors are arranged such that the distances between immediately adjacent deformation measuring sensors are unequal. Such an asymmetrical arrangement of the deformation measuring sensors allows, in particular, a particularly precise determination of the rotational position and / or the direction of rotation of the wave generator and / or the rotating transmission element relative to the gear. One advantage of an asymmetrical arrangement of a plurality of deformation measuring sensors with unequal spacing is that it enables measurements with greater precision and fewer ambiguities.If the strain measurement sensors are arranged symmetrically, certain periodic patterns can occur in the measurement signals that are ambiguous with regard to evaluation. By distributing the strain measurement sensors unevenly, this problem is avoided or at least reduced. An asymmetric sensor arrangement therefore makes it possible to determine finer details about the movement of the shaft generator or the gear element. In particular, by performing a Fourier analysis in combination with an asymmetric arrangement, particularly good evaluation results can be achieved to determine the rotational position and / or speed and / or direction of rotation of the shaft generator with particularly high accuracy.

[0046] In general, it can advantageously be provided that the deformation measurement sensors are arranged asymmetrically. Alternatively or additionally, the wave generator can also be designed asymmetrically. For example, the wave generator can be designed such that the cams that press the flexspline radially outward (which are identical if the wave generator has an elliptical cross-section) differ from one another, for example, with regard to their distance from the rotation axis and / or their curvature.

[0047] In a particularly versatile embodiment of the stress wave transmission according to the invention, it is provided that the at least one deformation measuring sensor detects, in addition to the deformation of the gearwheel or of the transmission component connected to the gearwheel caused by the shape of the wave generator, an additional deformation caused by a transmitted or supported torque of the loaded stress wave transmission, and that the evaluation device calculates a torque value from the detected additional deformation.

[0048] In an advantageous embodiment, the stress wave gear unit is equipped with an additional encoder for detecting the rotational position, speed, and / or direction of rotation of the wave generator or a gear element rotating with the reduction ratio, particularly relative to the gear or flexspline. This addition can significantly increase the accuracy of the measured values. While measurement via deformation sensors already enables precise indirect detection, the additional encoder allows for direct and redundant measurement, which can verify the measured values ​​and detect potential measurement errors. Particularly in applications with high demands on position accuracy, such as in robotics or precision drives, the combination of both measurement methods can ensure outstanding accuracy and operational reliability.

[0049] There are no fundamental restrictions regarding the design of the rotary encoder. The rotary encoder can advantageously comprise a rotary encoder sensor and a coding embodiment that interacts, preferably contactlessly, with the rotary encoder sensor, for example in the form of a graduation disk, a toothed ring, or a magnetic wheel. It can advantageously be provided that the rotary encoder sensor transmits its measurement signals to the evaluation device. The rotary encoder can, for example, be designed as an optical rotary encoder comprising a coding disk with printed or engraved markings, which is optically scanned by the rotary encoder sensor. Another variant is a magnetic rotary encoder that uses a Hall sensor or a magnetoresistive sensor to detect the movement of a permanent-magnetic ring or a magnetized gear rim.Alternatively, an inductive encoder can be used, which detects the movement of a metallic target object across an electromagnetic field. Another option is a capacitive encoder, which measures changes in capacitance between rotating and stationary electrodes.

[0050] A particularly advantageous design is one in which at least part of the rotary encoder and the evaluation device are arranged on a common carrier, in particular on a common circuit board. This integration reduces assembly effort and saves space, as the sensors can be compactly integrated into the system. Furthermore, cabling effort is reduced, which lowers both manufacturing costs and the risk of contact problems or electromagnetic interference. A combination of rotary encoder and evaluation device arranged on a common circuit board also allows for reliable, more direct signal processing, as long signal cables are avoided. This design offers the advantage of synergy, as the arrangement on a common carrier achieves great compactness and reliable signal processing.

[0051] The stress wave gear unit can advantageously be designed such that the evaluation device and at least part of the encoder, in particular the entire encoder, are arranged axially in the area of ​​the flexspline. This positioning optimally utilizes the available installation space and enables a compact design of the gear unit. At the same time, it allows for a direct coupling of the encoder to the gear element to be measured, enabling measurements with less backlash and greater precision. This arrangement offers significant advantages, as the sensor technology is compactly integrated into the existing mechanical structure of the gear unit. This design also has the advantage of synergy, as this special arrangement achieves good use of installation space and reliable signal processing.

[0052] An actuator which has a drive motor and a transmission according to the invention, which is connected downstream of the drive motor in terms of drive technology, is particularly advantageous. It can be provided that the evaluation device controls or regulates the drive motor depending on the measurement signals. Alternatively, the actuator can have a control device which receives signals from the evaluation device and which controls or regulates the drive motor depending on the measurement signals. In particular, this makes it possible, for example, to set a predetermined or predeterminable rotational position of the shaft generator or the flexspline. It is also possible, for example, to regulate the rotational speed of the shaft generator or the flexspline to a predetermined or predeterminable speed value. It is also possible, for example, to set the direction of rotation of the shaft generator or the flexspline to a predetermined or predeterminable direction of rotation.

[0053] A robot, in particular an industrial robot, that includes at least one gear mechanism or actuator according to the invention is particularly advantageous. In particular, the gear mechanism according to the invention can be used in a robot joint. The robot joint can be used and monitored in a particularly versatile manner through the use of the gear mechanism according to the invention.

[0054] Of particular advantage is a chassis, in particular an active chassis, for a motor vehicle that has at least one transmission or actuator according to the invention. A particularly advantageous feature is that high overload protection and reliable monitoring of the transmission can be easily implemented, thus increasing driving safety. A steering system, in particular a car steering system or a truck steering system, that has at least one transmission according to the invention is of particular advantage. The steering system can, in particular, be a power steering system and / or a superimposed steering system.

[0055] The subject matter of the invention is illustrated schematically and by way of example in the drawing and is described below with reference to the figures, wherein identical or similarly acting elements are generally provided with the same reference numerals even in different embodiments. In the drawings:

[0056] Fig. 1 shows a first embodiment of a stress wave transmission according to the invention,

[0057] Fig. 2 shows a connector of the first embodiment of a stress wave transmission according to the invention, Fig. 3 shows a second embodiment of a stress wave transmission according to the invention,

[0058] Fig. 4 is a detailed view of a second embodiment with a view along the rotation axis, wherein the gear housing and the evaluation device are not shown,

[0059] Fig. 5 the circular spline of the second embodiment,

[0060] Fig. 6 shows the rear view of one of the connectors for a stress wave transmission according to the invention according to the second embodiment,

[0061] Fig. 7 shows the front view of one of the connectors for an inventive

[0062] Stress wave transmission according to the second embodiment,

[0063] Fig. 8 is a side view of one of the connectors for a

[0064] Stress wave transmission according to the second embodiment,

[0065] Fig. 9 is a detailed view of a third embodiment of an inventive

[0066] Stress wave gear with a view along the rotation axis, whereby the gear housing and the evaluation device are not shown,

[0067] Fig. 10 shows a fourth embodiment of a stress wave transmission according to the invention,

[0068] Fig. 1 1 shows a fifth embodiment of a stress wave transmission according to the invention, and

[0069] Fig. 12 shows a sixth embodiment of a stress wave transmission according to the invention.

[0070] Fig. 1 shows a first embodiment of a stress wave transmission according to the invention in a cross-sectional view along the rotation axis 28.

[0071] The stress wave transmission has a wave generator 1, which is mounted for rotation about a rotation axis 28 relative to a flexspline 2 by means of a radially flexible roller bearing 12. The flexspline 2 has an external toothing 3. The stress wave transmission also has a gear 4, which forms a circular spline 15 and has an internal toothing 5. The internal toothing 5 engages with the external toothing 3 of the flexspline 2 at two opposite points. Arranged on the brim of the hat-shaped flexspline 2 is a flange 6, which is elastically movably connected to the outer ring 8 of a crossed roller bearing 9 by means of several connectors 7 arranged offset in the circumferential direction. The flange 6 can be designed in several parts to facilitate assembly of the stress wave transmission, although this is not shown for the sake of clarity.An inner ring 10 of the crossed roller bearing 9 is rotationally and rigidly connected to the gear 4. The outer ring 8 of the crossed roller bearing 9 is rotationally and rigidly connected to a gear housing 11.

[0072] The flange 6 has a plurality of radial plug-in recesses 13 for first plug-in sections 14 of the connectors 5, which have a U-shaped cross section. The outer ring 8 of the crossed roller bearing 9 has a plurality of radial plug-in recesses 13 for plug-in sections 14 of the connectors 7, which have a U-shaped cross section.

[0073] For example, the wave generator 1 can act as a gear drive and the circular spline 15 as a gear output, while the flex spline 2 attached to the gear housing 11 via the flange 6, the connectors 7 and the outer ring 8 acts as a fixed shaft.

[0074] Each of the connectors 7 forms a deformation sensor 16, which measures a deformation, in particular a radial deformation, of the gear 4 and / or of a transmission component connected to the gear 4 or to the flexspline 2, namely the flange 6, caused by the shape of the wave generator 1. For this purpose, each connector 7 has strain gauges 18 glued to a deformation section 17.

[0075] The stress wave transmission also has an evaluation device 19 that receives measurement signals from the at least one deformation measurement sensor 16 and uses the measurement signals to determine the rotational position and / or the rotational speed and / or the direction of rotation of the wave generator 1 and / or the flexspline 2 (and / or another rotating transmission element) relative to the gear 4. The evaluation device 19 has an annular plate that is attached to the outer ring 8.

[0076] Figure 2 shows a very schematic perspective detailed view of one of the connectors 7 of the first embodiment of a transmission according to the invention. The two legs of the U-shaped connector 7 function as plug-in sections 14, which are inserted into the radial plug-in recesses 13 of the flange 6 and the outer ring 8. In addition, fastening (not shown in Figure 11) can be achieved by means of screws (not shown) that extend through bores 20 in the legs of the U-shaped connector 7. The section connecting the legs of the U-shaped connector 7 functions as a deformation section 17, to which strain gauges 18 are glued to detect the respective elastic deformation.

[0077] Figure 3 shows a second embodiment of a stress wave transmission according to the invention. The stress wave transmission has a transmission housing 11 and a gear 4, namely a circular spline 15. The gear 4 (circular spline 15) is shown separately in Figure 5. The circular spline 15 is rotationally connected to the transmission housing 11.

[0078] The gear 4 (circular spline 15) has a first gear component element 21 and a second gear component element 22, which are elastically movably connected to one another by means of four connectors 7, each of which is fastened to the first gear component element 21 and the second gear component element 22. The first gear component element 21 is designed as a ring and has a plurality of axial bores, which are designed as plug-in recesses 13 for plug-in pins 23 of the connectors 7. The second gear component element 22 is designed as an internally toothed ring and also has a plurality of axial bores, which are designed as plug-in recesses 13 for plug-in pins 23 of the connectors 7.

[0079] The stress wave transmission also features a radially flexible, externally toothed, cup-shaped flexspline 2, which is arranged axially in the area of ​​its toothing in the space surrounded by the circular spline 15 and has a flange 6 at the bottom of the cup. Arranged within the flexspline 2 is a wave generator 1 with a radially flexible rolling bearing 12, which has an inner ring 24, an outer ring 25, and rolling elements 26. The wave generator 1 is rotationally connected to a transmission drive shaft 27. The wave generator 1 bends the flexspline 2 into an oval shape in order to engage the toothings of the circular spline 15 and the flexspline 2 along the vertical axis of the wave generator 1.

[0080] Each of the connectors 7 forms a deformation sensor 16, which measures a deformation, in particular a radial deformation, of the gear 4 and / or of a transmission component connected to the gear 4 or to the flexspline 2, namely the flange 6, caused by the shape of the wave generator 1. For this purpose, each connector 7 has strain gauges 18 glued to a deformation section 17.

[0081] The stress wave transmission also has an evaluation device 19, which receives measurement signals from the at least one deformation measurement sensor 16 and which determines the rotational position and / or the speed and / or the direction of rotation of the wave generator 1 and / or the flexspline 2 (or another rotating transmission element) relative to the gear 4 from the measurement signals. The evaluation device 1 can be ring-shaped and fastened to the transmission housing 11. Figure 4 shows a detailed view of a second exemplary embodiment, viewed along the rotation axis 28, wherein, among other things, the transmission housing 11 and the evaluation device 19 are not shown for the sake of clarity.

[0082] Figure 5 shows the circular spline of the second embodiment shown separately.

[0083] Figures 6 to 8 show various views of one of the connectors 7 of the stress wave transmission according to the invention shown in Figure 3. Figure 6 shows the rear view of one of the connectors 7. This figure shows that the connector 7 has a V-shaped deformation section 17, which can be made, for example, from a punched sheet metal. A strain gauge 18 is glued to the back of each leg of the V-shaped deformation section 17, which makes it possible to measure the tensile or compressive forces acting on the legs of the V-shaped deformation section 17.

[0084] On the V-shaped deformation section 17, protruding plug pins 23 are arranged on the front side, which are inserted into the plug recesses 13.

[0085] Figure 9 shows a detailed view of a third embodiment of a stress wave transmission according to the invention, viewed along the rotation axis, with the transmission housing and the evaluation device not shown.

[0086] Stress wave gear is essentially constructed in the same way as the

[0087] Stress wave transmission according to the second embodiment. However, the gear 4, which forms the circular spline 15, has an asymmetrical arrangement of the connectors 7.

[0088] Figure 10 shows a fourth embodiment of a stress wave transmission according to the invention. The stress wave transmission has a transmission housing 11 and a gear 4, namely a circular spline 15. The circular spline 15 is rotationally connected to the transmission housing 11.

[0089] The gear 4 (circular spline 15) has a first gear component element 21 and a second gear component element 22, which are elastically movably connected to one another by means of four connectors 7, each of which is fastened to the first gear component element 21 and the second gear component element 22. The first gear component element 21 is designed as a ring and has a plurality of axial bores, which are designed as plug-in recesses 13 for plug-in pins 23 of the connectors 7. The second gear component element 22 is designed as an internally toothed ring and also has a plurality of axial bores, which are designed as plug-in recesses 13 for plug-in pins 23 of the connectors 7. The stress wave transmission also has a radially flexible externally toothed annular flexspline 2, which is arranged axially in the region of its toothing in the spatial volume surrounded by the circular spline 15 and another gear 31, namely a dynamic spline 29.The dynamic spline 29 is rotationally connected to an output shaft 32. Arranged within the flex spline 2 is a wave generator 1 with two radially flexible rolling bearings 12, each with an inner ring 24, an outer ring 25, and rolling elements 26. The wave generator 1 is rotationally connected to a transmission input shaft 27. The wave generator 1 bends the flex spline 2 into an oval shape to engage the teeth of the circular spline 15 and the flex spline 2 along the vertical axis of the wave generator 1.

[0090] Each of the connectors 7 forms a deformation sensor 16, which measures a deformation of the gear 4 caused by the shape of the wave generator 1, in particular a radial deformation. For this purpose, each connector 7 has strain gauges 18 glued to a deformation section 17.

[0091] The stress wave transmission also has an evaluation device 19 that receives measurement signals from the at least one deformation measurement sensor 16 and uses the measurement signals to determine the rotational position and / or the rotational speed and / or the direction of rotation of the wave generator 1 and / or the flexspline 2 (or another rotating transmission element) relative to the gear 4. The evaluation device 19 can be ring-shaped and attached to the transmission housing 11.

[0092] Figure 11 shows a fifth embodiment of a stress wave transmission according to the invention. The stress wave transmission has a transmission housing 11 and a gear 4, namely a circular spline 15.

[0093] The circular spline 15 is rotationally connected to an annular gear component 30. The gear component 30 is rotationally connected to the gear housing 11.

[0094] The transmission component 30 has a first transmission component element 21 and a second transmission component element 22, which are elastically movably connected to one another by means of connectors 7, which are respectively fastened to the first transmission component element 21 and to the second transmission component element 22. The first transmission component element 21 is designed as a ring and has a plurality of axial bores, which are designed as plug-in recesses 13 for plug-in pins 23 of the connectors 7. The second transmission component element 22 is designed as an internally toothed ring and likewise has a plurality of axial bores, which are designed as plug-in recesses 13 for plug-in pins 23 of the connectors 7. The stress wave transmission also has a radially flexible, externally toothed, pot-shaped flexspline 2, which is arranged axially in the region of its toothing in the space surrounded by the circular spline 15 and which has a flange 6 on the pot base.Arranged within the flexspline 2 is a wave generator 1 with a radially flexible rolling bearing 12, which has an inner ring 24, an outer ring 25, and rolling elements 26. The wave generator 1 is rotationally connected to a transmission drive shaft 27. The wave generator 1 bends the flexspline 2 into an oval shape to engage the teeth of the circular spline 15 and the flexspline 2 along the vertical axis of the wave generator 1.

[0095] Each of the connectors 7 forms a deformation sensor 16, which measures a deformation of the transmission component 30 caused by the shape of the wave generator 1, in particular a radial deformation. For this purpose, each connector 7 has strain gauges 18 glued to a deformation section 17.

[0096] The stress wave transmission also has an evaluation device 1, which receives measurement signals from the at least one deformation measurement sensor 16 and determines the rotational position and / or the rotational speed and / or the direction of rotation of the wave generator 1 and / or the flexspline 2 (or another rotating transmission element) relative to the gear 4 from the measurement signals. The evaluation device 19 can be ring-shaped and attached to the transmission housing 11.

[0097] Figure 12 shows a sixth embodiment of a stress wave transmission according to the invention. The sixth embodiment is essentially constructed in the same way as the first embodiment, but unlike the first embodiment, an additional rotary encoder 35 is provided for determining the rotational position, speed, and / or direction of rotation of a transmission element rotating with the reduction ratio, namely the inner ring 10 connected to the circular spline 15. While the measurement via the deformation sensors 16 already enables precise detection, the additional rotary encoder 35 allows for redundant measurement, whereby the measured values ​​can be verified and possible measurement errors can be detected.

[0098] The rotary encoder 35 has a rotary encoder sensor 33 and a coding embodiment 34 that interacts contactlessly with the rotary encoder sensor 33, for example in the form of a line disk, a line ring of a toothed ring or a magnetic wheel.

[0099] The rotary encoder sensor 33 and the evaluation device 19 are arranged on a common carrier 36, in particular on a common printed circuit board.

[0100] In addition, the evaluation device 19 and the rotary encoder 35 are arranged axially in the area of ​​the flexspline 2.

[0101]

[0102] 1 wave generator

[0103] 2 Flexsplines

[0104] 3 External gearing

[0105] 4 gear

[0106] 5 Internal gearing

[0107] 6 Flange

[0108] 7 connectors

[0109] 8 Outer ring

[0110] 9 crossed roller bearings

[0111] 10 inner ring

[0112] 1 1 Gearbox housing

[0113] 12 rolling bearings

[0114] 13 Plug-in recess

[0115] 14 plug-in sections

[0116] 15 Circular splines

[0117] 16 Deformation measuring sensor

[0118] 17 Deformation section

[0119] 18 strain gauges

[0120] 19 Evaluation device

[0121] 20 holes

[0122] 21 first transmission component element

[0123] 22 second transmission component element

[0124] 23 plug pins

[0125] 24 inner ring

[0126] 25 Outer ring

[0127] 26 rolling elements

[0128] 27 Gearbox drive shaft

[0129] 28 Rotation axis

[0130] 29 Dynamicspline

[0131] 30 Gearbox component

[0132] 31 additional gear

[0133] 32 Output shaft

[0134] 33 Encoder sensor

[0135] 34 Coding embodiment

[0136] 35 rotary encoders

[0137] 36 carriers

Claims

Patent claims 1. A stress wave transmission with a wave generator (1) which is mounted so as to be rotatable about an axis of rotation (28) relative to a flexspline (2), and with a gear (4) which meshes with the flexspline (2), characterized by a. at least one deformation measuring sensor (16) which measures a deformation, in particular a radial deformation, of the gear (4) and / or of a transmission component connected to the gear (4) or to the flexspline (2) caused by the shape of the wave generator (1), and by b. an evaluation device (19) which receives measurement signals from the at least one deformation measuring sensor and which determines from the measurement signals the rotational position and / or the speed and / or the direction of rotation of the wave generator (1) and / or of a transmission element rotating with the reduction ratio of the stress wave transmission, in particular relative to the gear (4) or relative to the flexspline (2).

2. Stress wave transmission according to claim 1, characterized in that the flexspline (2) is the transmission element rotating with the reduction ratio of the stress wave transmission or that the gear (4) is the transmission element rotating with the reduction ratio of the stress wave transmission.

3. Stress wave transmission according to claim 1 or 2, characterized in that a. the flexspline (2) has external teeth and that the gear (4) is an internally toothed ring gear, and / or that b. the gear (4) is a circular spline (15) or a dynamic spline.

4. Stress wave transmission according to one of claims 1 to 3, characterized in that a. the transmission component is a transmission housing (11), or that b. the transmission component is part of a bearing, or that c. the transmission component is an inner ring or an outer ring of a rolling bearing, or that d. the transmission component is a flange (6), or that e. the transmission component is a flange (6) connected to the flexspline (2), or that f. the transmission component is a flange (6) connected to the gear (4).

5. Stress wave transmission according to one of claims 1 to 4, characterized in that the evaluation device (19) records the measuring signals as a function of time.

6. Stress wave transmission according to one of claims 1 to 5, characterized in that the deformation measuring sensor (16) has at least one strain gauge.

7. Stress wave transmission according to one of claims 1 to 6, characterized in that the deformation measuring sensor (16) has at least one deformation section (17) whose shape changes continuously and repeatedly during rotation of the wave generator (1), in particular also when the stress wave transmission is unloaded.

8. Stress wave transmission according to claim 6, characterized in that the deformation section (17) is a pressure section which experiences a continuously changing pressure load during rotation of the wave generator (1), in particular also when the stress wave transmission is unloaded.

9. Stress wave transmission according to claim 6, characterized in that the deformation section (17) is a tensile section which experiences a continuously changing tensile load during rotation of the wave generator (1), in particular also when the stress wave transmission is unloaded.

10. Stress wave transmission according to claim 6, characterized in that the deformation section (17) is continuously and alternately subjected to compression and tension during rotation of the wave generator (1), in particular also when the stress wave transmission is unloaded. 1 1. Stress wave transmission according to claim 6, characterized in that the deformation section (17) experiences a continuously changing bending load and / or shear load during rotation of the wave generator (1), in particular also when the stress wave transmission is unloaded.

12. Stress wave transmission according to one of claims 1 to 11, characterized in that the evaluation device (19) determines the respective current rotational position starting from an initial rotational position taking into account a measured temporal course of the measuring signals.

13. Stress wave transmission according to one of claims 1 to 12, characterized in that the deformation measuring sensor (16) is arranged on the gear (4) or on the transmission component.

14. Stress wave transmission according to one of claims 1 to 13, characterized in that the deformation measuring sensor (16) is formed on a connector or is part of a connector which a. connects two gear component elements of the gearwheel (4) to one another, in particular in an elastically movable manner, or b. connects two gear component elements of the gear component to one another, in particular in an elastically movable manner, or c. connects the gearwheel (4) to the gear component, in particular in an elastically movable manner, or d. connects the gear component to another gear component, in particular in an elastically movable manner, or e. connects the gear component to the flexspline (2), in particular in an elastically movable manner.

15. Stress wave transmission according to one of claims 1 to 14, characterized in that several deformation measuring sensors (16) are present.

16. Stress wave transmission according to claim 15, characterized in that the deformation measuring sensors (16) are arranged distributed in the circumferential direction.

17. Stress wave transmission according to claim 15 or 16, characterized in that the deformation measuring sensors (16) are arranged such that the distances between immediately adjacent deformation measuring sensors (16) are equal.

18. Stress wave transmission according to claim 15 or 16, characterized in that the deformation measuring sensors (16) are arranged such that the distances between at least two immediately adjacent deformation measuring sensors (16) are unequal.

19. Stress wave transmission according to claim 15 or 16, characterized in that the deformation measuring sensors (16) are arranged asymmetrically.

20. Stress wave transmission according to one of claims 1 to 1 , characterized in that the wave generator (1) is designed asymmetrically.

21. Stress wave transmission according to one of claims 1 to 20, characterized in that the at least one deformation measuring sensor (16) detects, in addition to the deformation of the gear (4) or of the transmission component connected to the gear (4) caused by the shape of the wave generator (1), an additional deformation caused by a transmitted or supported torque of the loaded stress wave transmission, and in that the evaluation device (19) calculates a torque value from the detected additional deformation.

22. Stress wave transmission according to one of claims 1 to 21, characterized by an additional rotary encoder (35) for detecting the rotational position and / or the speed and / or the direction of rotation of the wave generator (1) and / or a Reduction ratio of the stress wave gear rotating gear element, in particular relative to the gear (4) or relative to the flexspline (2).

23. Stress wave transmission according to claim 22, characterized in that at least a part of the rotary encoder (35) and the evaluation device (19) are arranged on a common carrier, in particular on a common printed circuit board.

24. Stress wave transmission according to claim 22 or 23, characterized in that the evaluation device (1) and at least a part of the rotary encoder (35) are arranged axially in the region of the flexspline (2).

25. Actuator comprising a drive motor and a transmission according to one of claims 1 to 24, which is connected downstream of the drive motor.

26. Actuator according to claim 25, characterized in that a. the evaluation device (19) controls or regulates the drive motor depending on the measurement signals, or that b. a control device which receives signals from the evaluation device (19) controls or regulates the drive motor depending on the measurement signals.

27. Robot joint comprising at least one gear mechanism according to one of claims 1 to 24 and / or an actuator according to claim 25 or 26.

28. A robot comprising at least one gear mechanism according to one of claims 1 to 24 and / or an actuator according to claim 25 or 26.

29. Chassis, in particular active chassis for a motor vehicle, which has at least one according to one of claims 1 to 24 and / or an actuator according to claim 25 or 26.

30. Steering system, in particular car steering system or truck steering system, which has at least one transmission according to one of claims 1 to 24 and / or an actuator according to claim 25 or 26.

31. Steering system according to claim 30, characterized in that the steering system is a power steering system and / or a superposition steering system.

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