Parallel high-efficiency composite flexspline-based internal-meshing harmonic transmission in motor rotor

Abstract

A parallel high-efficiency composite flexspline-based internal-meshing harmonic transmission in a motor rotor. A moving component of the parallel high-efficiency composite flexspline-based internal-meshing harmonic transmission consists of a thin-walled composite flexspline and rolling wave generators; outer raceways of inner rings of flexible bearings and inner bevel gear rings are integrated at two ends of the thin-walled composite flexspline, and an inner gear ring is integrated in the middle thereof; the rolling wave generators are respectively and fixedly connected to two ends of a hollow inner rotor of a motor, the structural dimensions of the rolling wave generators being the same, but a semi-minor axis at one end being coplanar with a semi-major axis at the other end; a motor outer stator, to which two cap-shaped rigid gears are fixed, functions as a stationary component; by means of antisymmetric deformations of the two ends of the composite flexspline, half of an input torque of the motor is amplified in the same proportion by two back-to-back parallel internal-meshing harmonic transmission assemblies having same structural parameters, and, after superposition on a constant-circular middle section of the composite flexspline, the torque is output by means of a variable-stiffness coupling formed by the inner-wall gear ring of the composite flexspline and a hollow splined shaft. Three waveform calculation formulas for the composite flexspline are provided, and a curvature inflection point value is introduced to determine the meshing mode between the composite flexspline and the bevel teeth of the rigid gears; the wall thickness of the composite flexspline is effectively reduced, and the middle section does not require a circularity-maintaining constraint, such that the elastic deformation energy and friction power consumption can be reduced, thus achieving high transmission efficiency.

Description

Parallel high-efficiency composite flexible tube meshing harmonic speed changer in motor rotor TECHNICAL FIELD

[0001] The present application belongs to the field of mechanical transmission technology, and particularly relates to five kinds of parallel high-efficiency composite flexible tube meshing harmonic speed changers in motor rotor. The present application proposes the idea and technical method of realizing two meshing harmonic transmission assemblies sharing a composite flexible tube and working in a back-to-back parallel mode by means of electromechanical fusion. The total deformation energy consumption and friction power loss of the speed changer are reduced by integrating and reducing some static and dynamic parts and the material of non-working flexible parts, and by making the elastic deformation forces in the moving parts offset each other. Since the speed changer is built into the rotor of the driving source, the motor, the deformation of the active meshing radial harmonic speed changer is reasonable, the structure is compact, the volume is small, the transmission is coaxial, and the transmission efficiency is high. BACKGROUND

[0002] Harmonic speed reducers have the characteristics of small volume, large transmission ratio, high transmission precision, and light weight, and are the core transmission components of automatic control devices such as robots, mechanical equipment, and medical devices. With more and more devices developing towards automation and intelligence, higher and higher requirements are put forward for the performance of harmonic speed reducers. The commonly used commercial harmonic speed reducers on the market are all radial harmonic speed reducers with single outer meshing harmonic transmission assemblies, while the description of radial harmonic speed reducers with single inner meshing harmonic transmission assemblies [1, 2] or face-to-face parallel inner meshing radial harmonic speed reducers [2] in the rotor of the motor is only found in patent documents.

[0003] Unlike general transmission devices, the core principle of harmonic speed reducers is to use the elastic deformation of flexible components during operation to produce harmonic motion to transmit motion and power. The inner meshing radial harmonic speed reducer described in the patent document is mainly composed of a radial non-circular inner recess wave generator, a flexible bearing, a flexible gear with an inner tooth ring at the port end, and a rigid gear with the same modulus of outer teeth. The flexible bearing is embedded in the non-circular inner recess of the wave generator and installed on the flexible gear. When the wave generator operates, the flexible gear can produce controllable elastic deformation, allowing the inner tooth ring of the deformed flexible gear at both short shaft ends to mesh with the outer teeth of the rigid gear, and due to the small tooth difference between the rigid and flexible gears, the inner teeth of the deformed flexible gear at the long shaft end are completely disengaged from the outer teeth of the rigid gear, forcing the flexible gear to produce harmonic deformation motion to transmit motion and torque, achieving a large reduction ratio.

[0004] The flexible bearing inner ring and the flexspline are two core flexible parts of the internal meshing radial harmonic reducer, but they are manufactured by different parts, both of which will have the elastic wall thickness material required by the independent part processing process, but not needed in work, but these elastic wall thickness materials not needed in work will also produce elastic deformation and consume energy when the reducer works. The flexible bearing outer ring is manufactured in a circular shape before being embedded in the wave generator, but after being embedded in the wave generator, the outer ring becomes a non-circular concave shape as the wave generator and needs to withstand assembly bending stress, and the curvature of each radial section of the inner raceway will also change due to the non-circular wave generator, thereby affecting the high-speed operation and stress of the bearing rolling element. The assembly of separate parts inevitably increases the number of interfaces in the force or torque transmission path, complicates the constraints between parts, and reduces the structural strength of each part.

[0005] Patent CN 105090372 A [1] discloses a new type of harmonic gear transmission device with an external wave generator, which adopts a wine cup-shaped flexspline; and patent US 7,409,891 B2 [2] discloses a radial harmonic reducer with a single internal meshing harmonic transmission assembly in the motor rotor driven by a belt pulley and a radial harmonic reducer with a face-to-face parallel internal meshing double harmonic transmission assembly in the motor rotor. The latter three reducers all adopt the internal meshing harmonic transmission assembly of the top hat-shaped flexspline, so both patents have the same problem as the existing flexspline type harmonic reducer, i.e. the inner gear ring end of the flexspline produces harmonic reduction movement and amplifies torque, while the torque output at the other end of the flexspline needs to rely on the diaphragm structure such as the cup bottom or hollow flange of the hat to provide circular constraint, which consumes elastic deformation energy when working. This is one of the main reasons for the low transmission efficiency of the existing flexspline type harmonic reducer. The radial harmonic reducer with a face-to-face parallel internal meshing double harmonic transmission assembly in the motor rotor simply connects the inner gear ring ends of the internal meshing harmonic transmission assemblies of two top hat-shaped flexsplines face-to-face in the middle of the motor inner rotor, driven by the same wave generator, while the torque output at both ends still relies on the hollow flange diaphragm structure to provide circular constraint, so it only increases the transmission power of the reducer, but does not improve its efficiency.

[0006] The document [2] is characterized in that each point on the circumference of the opening end of the flexible gear rotates and swings outward and inward with the maximum swing value with the hat edge cross section point on the flexible gear generatrix as the center during rotation. The swing value of the straight toothed ring at the port is not equal, but the teeth on the rigid and flexible gears are processed as parallel straight gears, causing additional elastic constraints when the rigid and flexible gears mesh at the short shaft end, increasing the sliding friction and wear of the meshing tooth surface. Patent CN 117847173 A [3] discloses a back-to-back parallel high-efficiency composite flexible cylinder outer meshing radial harmonic reducer that uses an internal bevel gear meshing method to perform harmonic meshing on the inclined end surface to fully utilize the elastic material of the flexible cylinder end, increase the meshing area, and reduce the deformation energy consumption.

[0007] The wave generator, flexible bearing, and flexible gear in the existing flexible gear type harmonic reducer are independent components of each other. The wave shape of the high-speed rotating wave generator is combined with the meshing of the rigid and flexible gear teeth with a small tooth difference, which converts the radial rotation wave of the flexible bearing high-speed moving ring into a harmonic motion of the low-speed moving ring and the flexible gear. Because there is only a single harmonic transmission assembly, the outward expansion and inward contraction of the opening end of the flexible gear, and the low-speed moving ring torsional stiffness of the flexible gear and the flexible bearing, the radial elastic deformation force of the flexible gear and the flexible bearing that is compressed together must be transmitted to the input bearing system of the wave generator and the output bearing system of the flexible gear through the interfaces of the three components, thereby generating large friction power consumption and heat on the two independent rotation degree of freedom bearing systems.

[0008] Because the radial displacement of the wave generator that determines the meshing and disengagement of the rigid and flexible gears in the existing flexible gear type harmonic reducer is generally several times larger than the play of conventional rolling bearings, the cage of the flexible bearing is forced to move or deform radially, and there is a large radial displacement between the cage and the balls. Although grease lubrication is used, the high-speed centrifugal motion of the balls often throws off the lubricating grease, which easily causes lubrication failure. SUMMARY

[0009] In view of the above-mentioned defects of the prior art, the present application provides five types of parallel high-efficiency composite flexible cylinder inner meshing harmonic reducers. The core principle is that the thin-walled composite flexible cylinder has an outer raceway and an inner bevel gear integrated on the outer surface of both ends, and a straight gear integrated on the inner wall of the middle part. Due to the rotation of the two types of rolling wave generators with the same structure and size, but with the opposite ends of the half short shaft and the half long shaft coplanar, the anti-symmetric deformation is generated. Through the two inner meshing radial harmonic transmission assemblies with the same module and tooth difference that are parallel and back-to-back, the high-speed rotating torque input to the reducer by the motor inner rotor is amplified by the same proportion. The low-speed rotating torque of the same direction at both ends is superimposed on the constant circle cross section of the composite flexible cylinder, and then output by the toothed ring on the inner wall of the composite flexible cylinder and the gear on the hollow shaft.

[0010] The parallel high-efficiency compound flexible tube meshing harmonic transmission in motor rotor is composed of moving parts, static parts and variable stiffness tooth coupling output in radial and axial compact. The moving parts are composed of the above-mentioned thin-walled compound flexible tube and two types of different groups of bending wave generators with the same structure size, but the half-length shaft at one end and the half-short shaft at the other end are in the same axial plane, which are fixed at both ends of the hollow inner rotor of the motor. The two rigid end covers integrated with bevel gears are fixed on the outer stator of the motor to form the static part. By using the feature that the cross section of the compound flexible tube always maintains circular during the operation, that is, there is no radial displacement of each point on the circumference of the cross section tube wall, only different direction micro deflection exists, the inner straight tooth ring is integrated on the inner wall of the cross section, and the rigid herringbone straight gear with the same modulus and tooth number on the hollow shaft forms the axial low stiffness and circumferential high stiffness coupling output. The modulus and tooth number difference of the two bevel gears and the inner bevel gears at both ends of the compound flexible tube are the same. At the inner shrink arc segment of the half-short shaft end at both ends of the compound flexible tube, the bevel gears mesh with the part of the non-circular bevel gears of the compound flexible tube in the bevel gear mode, so as to achieve the purpose of fully utilizing the deformation of the thin-walled cylinder, gear meshing and bearing support, optimizing the elastic material at the end of the compound flexible tube, improving the meshing area and reducing the deformation and friction energy consumption at this place.

[0011] The herringbone tooth cross section of the variable stiffness tooth coupling output must be located on the cross section of the compound flexible tube, and the tooth length direction generatrix of the tooth top and tooth root of the two herringbone straight teeth is parallel to the tooth profile generatrix of the inner bevel gears at the maximum shrink angle at both ends of the compound flexible tube. Through the meshing transmission of the variable stiffness tooth coupling, the low-speed rotating torque can be output, so as to reduce the constraint of the output coupling on the micro deflection deformation of each point on the circumference of the cross section of the compound flexible tube and the deformation of the points near the micro deflection deformation, and effectively reduce the constraint energy consumption at this place. The radial and axial external force outside the rotating torque output end is borne by a pair of angular contact ball bearings between the hollow toothed shaft and the fixed end cover.

[0012] There are two types of rolling wave generators: one type is a wave generator with the same structure size, but the half-length shaft at one end and the half-short shaft at the other end are coplanar, the inner surface of the flexible bearing outer ring inner raceway, and can generate two or three groups of concave bending waves. The wave generator is assembled by two identical equal-diameter balls-retainer assemblies; the other type is assembled by two unequal-diameter ball sets in the retainer and thick-walled circular raceway bearing outer ring. The radial and circumferential relative positions between the two unequal-diameter balls of the two unequal-diameter ball sets driven by the retainer in the work remain unchanged, the outer envelope of the ball set is a circle, and the inner envelope can be two or three groups of concave bending waves, so the inner envelope of the two unequal-diameter ball sets can ensure that the half-length shaft at one end and the half-short shaft at the other end are coplanar.

[0013] The features that each point on the circumference of the composite flexible tube port is in the maximum swing value when the point on the generatrix is in the inner shrink and outer swing in the rotating work, that is, the swing value of the axial points on the end bevel gear wheel teeth is not equal, the tooth length direction generatrix of the rigid gear tooth root meshed with the bevel gear in the inclined end surface should be designed to be parallel to the tooth length direction generatrix of the bevel gear outer contour at the maximum inner shrink angle of the composite flexible tube, and the tooth length direction generatrix of the rigid gear tooth top should be designed to be parallel to the tooth length direction generatrix of the bevel gear outer contour at the maximum outer swing angle of the composite flexible tube; in this case, the tooth end chamfer is used, the difference between the half long axis and the half short axis of the wave generator is 1 / 3 or less as the separation gap, and 2 / 3 or more of the length difference is used as the bevel gear meshing height to increase the meshing area, and the material quantity of the flexible tube end part is effectively reduced due to the shared part of the material of the bearing inner ring raceway, which can maximize the meshing area and reduce the deformation energy consumption of the composite flexible tube at this part, and the half taper angle of the inner bevel gear ring of the composite flexible tube end part needs to be determined by comprehensively considering the length / diameter ratio of the composite flexible tube, the diameter and curvature of the bearing inner ring raceway groove bottom, and the half long axis length / half short axis length of the non-circular inner concave wave generator.

[0014] The moving parts of the transmission and the inner rotor of the motor are supported or suspended by the inner shrink arc segment teeth at the half short axis end of the two ends of the composite flexible tube, and are coaxial with the two rigid gears; the axial displacement of the ball-retainer assembly is constrained by the outer swing and inner shrink deformation of the composite flexible tube port, and the coaxial rigid gear and the composite flexible tube bevel gear meshing constraint; in addition, the hollow shaft supported by the angular contact ball bearing can assist in constraining the radial and axial displacement of the inner rotor through the composite flexible tube middle section through the variable stiffness tooth profile coupling, so that the stator and rotor of the motor do not need to be supported by bearings, thereby reducing the number of bearings required, simplifying the structure of the reducer, reducing unnecessary friction loss and temperature rise, and the separation of the motor compartment and the transmission compartment can be solved by a pair of sealing rings between the moving parts and the end cover; of course, the moving parts of the transmission and the inner rotor of the motor can also be radially supported in the two end covers by a pair of deep groove ball bearings with sealing rings, to ensure coaxial operation with the two rigid gears, and to separate the motor compartment and the transmission compartment; because the elastic deformation forces on the two inner meshing radial harmonic drive assemblies working in back-to-back parallel on the composite flexible tube cancel each other out in the moving parts, there is no axial force on the deep groove ball bearing.

[0015] The cylindrical coordinate calculation formula of two or three groups of equal bending wave surface of the composite flexible tube with the end half long axis and the other end half short axis coplanar is:

[0016] ;

[0017] Wherein, R=(r o +r i ) / 2 is the constant radius of the middle section of the thin-walled composite flexible tube, ro r is the length of the half long axis of the composite flexible cylinder end face, R is the length of the half long axis of the composite flexible cylinder end face, r is the length of the half short axis of the composite flexible cylinder end face, L is the length of the composite flexible cylinder; for the composite flexible cylinder with the number n of curved waveforms, the curvature inflection point value at the half short axis is 1 / n i r is the length of the half long axis of the composite flexible cylinder end face, R is the length of the half long axis of the composite flexible cylinder end face, r is the length of the half short axis of the composite flexible cylinder end face, L is the length of the composite flexible cylinder; for the composite flexible cylinder with the number n of curved waveforms, the curvature inflection point value at the half short axis is 1 / n 2 When ε=(R-r i ) / r i is less than the curvature inflection point value, the part of the conical gear of the rigid gear wheel meshing with the non-circular conical gear ring of the composite flexible cylinder in the inner contraction arc segment at the half short axis end of the two ends of the composite flexible cylinder is in radial co-curvature meshing; when ε is greater than the curvature inflection point value, the same part of the conical gear will be in radial reverse curvature meshing, and the number of meshing teeth will be less than that in the co-curvature meshing.

[0018] For the second type of rolling wave generator, two or three groups of curved surfaces at the two ends of the composite flexible cylinder are rolled by balls with different diameters to form the inner envelope shape, and the deformation amount at the contact position of each ball and the composite flexible cylinder is always constant, thereby controlling the sequential rotation of each curved deformation surface in the circumferential direction, and the deformation amount changes from zero to small to large, and then back to small and zero, and the cycle is repeated; the radial force on all balls is borne by the outer ring of the thick-walled circular raceway bearing which is free to rotate, but the resultant force thereon is zero; unlike the first type of rolling wave generator, the cage of this type of rolling wave generator has no radial bending and the radial displacement of each ball with different diameters is very small, so it can be lubricated by solid oil to avoid the centrifugal throwing of lubricating grease due to high-speed movement of the ball and to increase the resistance to abrasive contamination; when the curvature at the half short axis end of each group of curved wave surfaces is less than the corresponding inflection point value, this type of rolling wave generator can change the constant cross-sectional radius in the composite flexible cylinder to change the number of tooth difference and thereby change the reduction ratio without increasing the volume of the speed reducer by adjusting the ball spacing or the number of balls or the ball diameter of the ball group with different diameters. Because the constraint of the elastic film structure at the cup bottom or the hollow flange cap along of the output end of the original flexible gear type internal meshing harmonic reducer or face-to-face parallel internal meshing harmonic reducer is removed, the deformation energy consumption of the original harmonic reducer or face-to-face parallel internal meshing harmonic reducer in operation is eliminated; because the flexible cylinder with a conical gear ring and the two inner rings of the flexible bearing are combined into one flexible part, the wall thickness of the elastic part of the original independent parts required by the machining process but not needed in operation is greatly reduced, and the multidirectional friction between the independent parts in operation is eliminated, so the deformation energy and friction power loss of the flexible part, which is the most core part of the harmonic reducer, in operation can be greatly reduced; compared with the flexible gear type internal meshing harmonic reducer or face-to-face parallel internal meshing harmonic reducer with only a single harmonic transmission assembly, under the same input power, the two internal meshing harmonic transmission assemblies working in back-to-back parallel mode have a reduced load by half, and under the same wall thickness of the flexible part for resisting bending and torsion, the wall thickness of the elastic part of the latter can be less than half of that of the former. The above-mentioned features can effectively improve the transmission efficiency of the reducer, reduce the temperature rise during operation, and reduce the failure rate of the flexible part.

[0019] Because the number of teeth of the inner cone gear ring on the composite flexible tube is slightly more than the number of teeth of the bevel gear on the two rigid end covers, in the case that the former only produces two sets of orthogonal antisymmetry deformation, such as the difference between the number of teeth is an odd multiple of 2, the two bevel gears of the latter need to be circumferentially misaligned by half a tooth for correct work; but if the difference between the number of teeth is an even multiple of 2, the latter does not need to be circumferentially misaligned; in the case that the former only produces three sets of antisymmetry deformation, such as the difference between the number of teeth is an odd multiple of 3, the two bevel gears of the latter need to be circumferentially misaligned by half a tooth for correct work; but if the difference between the number of teeth is an even multiple of 3, the latter does not need to be circumferentially misaligned; if the former is forced to produce more sets of antisymmetry deformation, the misalignment installation conditions of the two bevel gears of the latter are similar. The ball-retainer assembly only bears the composite flexible tube deformation and gear meshing force between the high-speed rotating inner rotor and the composite flexible tube raceway, which is only related to the structural size and material of the composite flexible tube and the output torque, and is an internal force, which is relatively stable and predictable; while the supporting bearing of the hollow shaft associated with the variable stiffness tooth profile coupling member bears varying external forces, but its speed is low, it is in the conventional working condition range of rolling bearings, and the installation space is large. That is, from the power input of the high-speed motor to the large reduction ratio output of the transmission, only a pair of generalized flexible bearings and a pair of angular contact ball bearings are used to comprehensively complete the deformation reduction, "suspended" moving parts and the inner rotor of the motor, share different nature of internal and external loads and work at high and low speeds respectively, which is clear division of labor and cooperation to bear the support of each structural member.

[0020] Even if the moving parts and static parts of the transmission are not integrated, but are assembled into discrete components, the name can remove the composite two words, but the function and advantage of the back-to-back parallel composite flexible tube internal meshing harmonic transmission are the same, only the radial size is larger, there are several interfaces in the force or torque transmission path, the transmission efficiency is slightly lower, but the manufacturing process is relatively more mature and simple.

[0021] The transmission can also be used in reverse to become a speed increaser, that is, the low-speed large-torque input can be converted into a high-speed low-torque output, so that the inner rotor motor can be replaced by a generator to realize a parallel high-efficiency composite flexible tube internal meshing harmonic speed increaser, thereby converting low-speed mechanical energy into electrical energy output. BRIEF DESCRIPTION OF DRAWINGS

[0022] Herein, Fig. 1 is a schematic diagram of a parallel high-efficiency composite flexible tube internal meshing harmonic transmission in a motor rotor with two sets of bending waveforms generated by a first type of rolling wave generator and three radial cross-sectional structures of a preferred embodiment of the present application.

[0023] Fig. 2 is a schematic diagram of a parallel high-efficiency composite flexible tube internal meshing harmonic transmission in a motor rotor with two sets of bending waveforms generated by a second type of rolling wave generator and a generalized flexible bearing structure driven by a retainer-driven eccentric diameter ball set of the present application.

[0024] Figure 3 is a radial cross-sectional view of the structure inside the high-efficiency compound flexible tube internal meshing harmonic speed variator in the motor rotor of the present application, which uses the second type of rolling wave generator to generate three sets of curved waveforms.

[0025] Figure 4 is a radial cross-sectional view of the structure inside the wave generator of the present application, which uses the first type of rolling wave generator to generate three sets of curved waveforms.

[0026] Figure 5 is a three-dimensional view of the curved wave surface of the compound flexible tube of the present application, which generates two to four sets of curved waveforms with the end half-long axis and the opposite end half-short axis coplanar, and the curved shape of the inner retracted arc segment at the half-short axis end varies with the value of (R-r i ) / r i .

[0027] Figure 6 is a radial support structure comparison diagram of the present application, which adds a pair of deep groove ball bearings with sealing rings between the moving part and the static part, and whether they are integrated or not. Key in the description of the drawing. DETAILED DESCRIPTION

[0028] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects more clear and explicit, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0029] In the following description, specific details are set forth in order to provide a thorough understanding of the embodiments of the present application for purposes of explanation and not for purposes of limitation. It will be obvious to one skilled in the art that the present application can be practiced without some or all of these specific details. In other instances, well-known systems, apparatuses, circuits, and methods have not been described in detail in order to not unnecessarily obscure the description of the present application.

[0030] In view of the problems described in the background, the present application will describe the high-efficiency compound flexible tube internal meshing harmonic speed variator in the motor rotor in combination with five examples.

[0031] Example One

[0032] As shown in Fig. 1, the embodiment provides a parallel high-efficiency composite flexible tube meshing harmonic speed variator in a motor rotor with two sets of curved waveforms generated by a first type of rolling wave generator. In the embodiment, the variator is composed of a moving part, a static part and a variable stiffness toothed coupling output in a compact radial and axial direction. The integrated moving part is composed of a thin-walled composite flexible tube 9 with an outer raceway and an inner bevel gear integrated into the outer surface of both ends, and a straight gear integrated into the inner wall of the middle part. The tube is fixed to both ends of a hollow inner rotor 12 of a motor with embedded permanent magnets 13 by bolts 4, and has the same structure and size as the wave generator 11, but the half long shaft at one end and the half short shaft at the other end are coplanar, the inner surface has a flexible bearing outer ring inner raceway, and can generate two sets of concave bending waves. The wave generator 11 is composed of two identical equal-diameter ball-retainer assemblies 10. The two rigid end covers 3 integrated with bevel gears are fixed to the housing 2 with the motor outer stator 15 by bolts 1, forming the static part. The power supply line 14 is inserted into the wall hole of the left end cover 3 and electrically connected to the outer stator 15.

[0033] As shown in Fig. 1 and the F-F cross-sectional view therein, a straight gear is integrated into the constant cross-section inner wall of the composite flexible tube 9, which, together with the rigid herringbone straight gear on the hollow shaft 7 with the same modulus and tooth number, forms an axial low stiffness and circumferential high stiffness coupling output. The herringbone tooth intersection cross-section must be located on the middle cross-section of the composite flexible tube 9, and the tooth length direction generatrix of the two herringbone straight tooth tips and the tooth profile generatrix of the maximum inward angle of the inner bevel gears at both ends of the composite flexible tube 9 are parallel. The inner straight gear and the large end of the inner bevel gears at both ends of the composite flexible tube 9 can have the same tooth type and tooth number, or different tooth types and tooth numbers. The radial and axial external force on the hollow shaft 7 is borne by a pair of angular contact ball bearings 6 between the hollow shaft 7 and the rigid end cover 3, which are positioned and pre-tightened on the hollow shaft 7 by a pair of nuts 8.

[0034] As shown in the D-D and E-E cross-sectional views in Fig. 1, the modulus and tooth number difference of the two bevel gear wheels 3 and the inner bevel gears at both ends of the composite flexible tube 9 is the same. In the inward arc segment at the half short shaft end of both ends of the composite flexible tube 9, the bevel gears of the gear wheels 3 mesh with the partial bevel gears of the non-circular bevel gears of the composite flexible tube 9 in the form of bevel gears, i.e. the two harmonic transmission assemblies actually perform the same proportional speed reduction work in parallel as shown in the functional block diagram. The moving part is supported or suspended by the inward arc segment gear meshing of the half short shaft end of both ends of the composite flexible tube 9 and coaxial with the two gear wheels 3 due to the two sets of orthogonal anti-symmetrical deformations of the composite flexible tube 9 at both ends. The axial displacement of the ball-retainer assembly 10 is constrained by the two sets of outward and inward deformations of the composite flexible tube 9 at both ends, as well as the bevel gear meshing of the shaft-symmetrical gear wheels 3 and the composite flexible tube 9. The hollow shaft 7 supported by a pair of angular contact ball bearings 6 also has an auxiliary constraint function through the variable stiffness toothed coupling member via the middle cross-section of the composite flexible tube 9, so that the motor does not need to be supported by bearings between the stator and the rotor, and the separation of the motor compartment and the variator compartment can be solved by a pair of sealing rings 5 between the moving part and the end cover.

[0035] As shown in Fig. 1, the tooth length direction generatrix of the tooth root of the bevel gear 3 must be parallel to the bevel gear outer profile generatrix at the maximum retraction angle of the composite flexible tube 9, and the tooth length direction generatrix of the tooth top of the gear wheel 3 must be parallel to the bevel gear outer profile generatrix at the maximum extension angle of the composite flexible tube 9; by means of tooth end chamfer, the difference between the length of the half major axis and the length of the half minor axis of the wave generator is used as the disengagement gap, and the difference between the length of the half major axis and the length of the half minor axis of the wave generator is used as the bevel gear meshing height, so as to increase the meshing area.

[0036] Example Two

[0037] The parallel high-efficiency composite flexible tube internal meshing harmonic speed changer in the motor rotor with two sets of curved waveforms generated by the second type of rolling wave generator and its generalized flexible bearing structure driven by the sun orbiting unequal diameter ball set of the retainer are shown in Fig. 2. The speed changer described in this embodiment still consists of a moving part, a stationary part and a variable stiffness tooth profile coupling output in the radial and axial directions. The integrated moving part is a thin-walled composite flexible tube 39 with flexible bearing inner ring outer raceway and inner bevel gear ring integrated on the outer surface of both ends, and a spur gear ring integrated on the inner wall of the middle part. It is assembled with the same structure size retainer fixed on both ends of the hollow inner rotor 42 of the motor embedded with permanent magnets 43, and the unequal diameter ball set 40 in the pocket hole and the thick-walled circular raceway bearing outer ring 41 that can withstand the radial force of the unequal diameter ball set without circumferential constraint. The two rigid end covers 33 integrated with bevel gears are fixed on the outer shell 32 with the motor outer stator 45 by bolts 31, forming the stationary part. The motor compartment and the speed changer compartment are separated by a pair of sealing rings 35 between the stationary part and the moving part. The radial and axial external force on the hollow shaft 37 is borne by a pair of angular contact ball bearings 36 between the hollow shaft 37 and the rigid end cover 33. The pair of bearings 36 are positioned and pre-tightened on the hollow shaft 37 by a pair of nuts 38. The power supply line 44 passes through the wall hole of the left end cover 33 and is electrically connected to the outer stator 45.

[0038] Fig.2b shows the schematic diagram of the generalized flexible bearing structure of the unequal-diameter ball set driven by the cage in revolution. The outer envelope of the ball set is a circle, because the circumferential relative position between the unequal-diameter balls in the unequal-diameter ball set 40 is fixed, although the interval can be unequal. The ball set rolls on the circular raceway of the thick-walled bearing outer ring 41. The bearing outer ring 41 is axially limited by the cage side surface of the cage in the unequal-diameter ball set 40 and the clamp 46 embedded in the inner wall of the motor hollow rotor, but it has no circumferential rotation constraint and can rotate at high speed while bearing the radial force of the unequal-diameter ball set. The inner envelope of the unequal-diameter ball set 40 is two sets of concave curved waves, which roll on the outer raceway of the flexible bearing inner ring integrated on the outer surface of the two ends of the composite flexible tube 39. Therefore, the two inner envelopes can ensure the realization of the orthogonal antisymmetry deformation of the end half long shaft and the other end half short shaft. The orthogonal curved surface of the two ends of the composite flexible tube 39 is the bending deformation state rolled by the two cage unequal-diameter ball sets 40. The deformation amount at the contact between each ball and the composite flexible tube 39 is always constant, thereby controlling the sequential rotation of each bending deformation surface along the circumference. The deformation amount changes from zero to small to large, and then back to small and zero, and then repeats. Since the radial and circumferential relative positions between the balls remain unchanged during operation, the cage has no radial movement or deformation, and the radial displacement between the cage and the balls is small. Therefore, solid oil solution can be used for lubrication to avoid the centrifugal throwing of lubricating grease by high-speed centrifugal motion of the balls and to increase the resistance to abrasive contamination. The radial force on all the balls must be borne by the thick-walled circular raceway bearing outer ring 41, but the resultant force on it is zero.

[0039] Example Three

[0040] Fig.3 shows the radial sectional view of the parallel high-efficiency composite flexible tube internal meshing harmonic speed variator in the motor rotor using the second type of rolling wave generator to generate three sets of curved waveforms and the inner structure of the unequal-diameter ball set driven by the cage in revolution. The variator described in this embodiment still consists of a moving part, a stationary part, and a variable stiffness toothed coupling output in the radial and axial directions. The integrated moving part is composed of a thin-walled composite flexible tube 59, whose outer surface at both ends integrates the outer raceway and the inner bevel gear, and whose inner wall in the middle also integrates a spur gear, which is assembled with the same structure and size cage at both ends of the motor hollow inner rotor 62 embedded with permanent magnets 63, the unequal-diameter ball set 60 in the pocket hole of the cage, and two thick-walled circular raceway bearing outer rings 61 that have no circumferential constraint but need to bear the radial force of the unequal-diameter ball set. The two rigid end covers 53 integrated with bevel gears are fixed on the outer shell 52 with the motor outer stator 65 by bolts 51, constituting the stationary part. A pair of sealing rings 55 separates the motor compartment from the variator compartment between the stationary and moving parts. The radial and axial external force on the hollow shaft 57 is borne by a pair of angular contact ball bearings 56 between the hollow shaft 57 and the rigid end covers 53, which are positioned and pre-tightened on the hollow shaft 57 by a pair of nuts 58. The power supply line 64 passes through the wall hole of the left end cover 53 and is electrically connected to the outer stator 65.

[0041] The G-G sectional view in Fig. 3 gives the radial section of the inner structure of the race driving revolved unequal diameter ball sets. It can be seen from the figure that the composite flexible tube 59 has three sets of curved wave forms, i.e. three half major axes and three half minor axes, which mesh with the rigid gear 53 teeth at the three half minor axis ends and disengage at the three half major axis ends. The outer envelope of each unequal diameter ball set of the race driving revolved two unequal diameter ball sets 60 is a circle, which rolls on the circular race of the thick wall bearing outer ring 61, which is axially limited by the race side of the race - unequal diameter ball set 60 and the clamp 66 embedded on the inner wall of the motor hollow rotor, but it has no circumferential rotation constraint and can rotate at high speed while bearing the radial force of the unequal diameter ball set. The inner envelope of the race - unequal diameter ball set 60 is three sets of concave curved waves, which rolls on the outer race of the flexible bearing inner ring integrated on the outer surface of both ends of the composite flexible tube 59, so that the two inner envelopes can ensure the realization of the anti-symmetrical deformation of the co-planar half major axis and half minor axis at both ends. The three sets of curved surfaces at both ends of the composite flexible tube 59 are rolled and deformed by the two race - unequal diameter ball sets 60, and the deformation amount at the contact between each ball and the composite flexible tube 59 is always constant, thereby controlling the sequential rotation of each curved deformation surface along the circumference, and the deformation amount changes from zero to small to large, and then back to small and back to zero, and so on. Since the radial and circumferential relative positions between the balls remain unchanged during work, the race has no radial movement or deformation, and the radial displacement between the race and the balls is small, so the solid oil scheme can be used for lubrication to avoid the throwing of lubricating grease by high-speed centrifugal motion of the balls, and to increase the resistance to abrasive contamination. The radial force on all the balls must be borne by the thick wall circular race bearing outer ring 61, which rotates freely, but the resultant force on it is zero.

[0042] As shown in the H-H sectional position in the G-G sectional view in Fig. 3, the entire sectional structure of the transmission is the same as that in Fig. 2a. When the composite flexible tube 59 has a concave curvature at each point of the three sets of curved wave forms, it meshes with the rigid gear cone teeth in a co-curvature manner in the radial direction, so the number of teeth difference between the rigid and flexible gears can be changed by adjusting the ball spacing or the number of balls or the ball diameter of the race - unequal diameter ball set 60 near the half major axis end, without increasing the volume of the transmission, so as to change the reduction ratio.

[0043] Example Four

[0044] As shown in Fig. 4, the embodiment only provides the radial section schematic diagram of the wave generator to produce three sets of curved waveforms in the inner structure of the first type of rolling wave generator. The rolling wave is generated by the wave generator 81 with the same structure size at both ends, but the half long axis at one end is coplanar with the half short axis at the other end, the inner surface with flexible bearing outer ring inner raceway, and the wave generator 81 can generate three sets of concave curved waves. It is composed of two identical equal-diameter ball-cage assemblies 80. As can be seen from Fig. 4, the composite flexible tube 59 also generates three sets of curved waveforms with the wave generator 81, that is, there are three half long axes and three half short axes, which are engaged at the ends of the three half short axes with the teeth of the rigid wheel 53, and are disengaged at the ends of the three half long axes of the rigid wheel 53. The three sets of curved surfaces at both ends of the composite flexible tube 59 are rolled and deformed by the wave generator 81 of the three sets of concave curved waves in the equal-diameter ball-cage assembly 80, but the deformation amount at the contact between each ball and the composite flexible tube 59 changes with the change of the circumferential position of the ball, and because the cage has radial movement or deformation, the radial movement amount between the cage and each ball is large, and it is impossible to lubricate with solid oil scheme. Since the two equal-diameter ball-cage assemblies 80 and the three sets of concave curved waves at both ends of the composite flexible tube 59 are not fixed, they cannot increase the constant circular radius R in the composite flexible tube 59 without increasing the volume of the speed reducer, and the structure outside the I-I section position in Fig. 4 is exactly the same as the front view of Fig. 1 (the I-I section corresponds to the D-D section in Fig. 1), which will not be described in detail.

[0045] Fig. 5 shows the three-dimensional shape of the composite flexible tube generating the two-four sets of curved wave surfaces with the half long axis at one end coplanar with the half short axis at the other end, and the law of the retracted arc segment curved shape at the half short axis end with the change of (R-r i ) / r i value, the horizontal column is n=2-4 sets of curved wave surfaces, and the vertical column is the law of the three sets of curved wave surfaces with the change of (R-r i ) / r i value, wherein Fig. 5a shows the cylindrical coordinates and their variables x, φ. As can be seen from the figure, when (R-r i ) / r i <1 / n 2 , each half short axis end is concave; when (R-r i ) / r i =1 / n 2 , each half short axis end is a straight line; but when (R-r i ) / r i >1 / n 2 , each half short axis end is convex.

[0046] Example Five

[0047] Figure 6 gives a pair of deep groove ball bearings with sealing rings between the moving part and the static part and the structure of the integrated or not. The left side is the embodiment improved on the basis of the first embodiment, which is a pair of deep groove ball bearings with sealing rings 5c between the moving part and the static part and the coplanar end cover 3c and the end half long shaft and the other end half short shaft, the inner surface of the flexible bearing outer ring inner raceway, the wave generator 11c can produce two sets of concave curved wave, to ensure the coaxial operation of the two, and attached to the motor compartment and the transmission compartment, because the elastic deformation force on the two parallel working back-to-back inner meshing harmonic transmission components in the composite flexible tube cancels out, so there is no axial force on the pair of deep groove ball bearings 5c.

[0048] Figure 6 right side gives the moving part and the static part without corresponding integration, but using discrete components to assemble into parallel flexible tube inner meshing harmonic transmission, which is also a pair of deep groove ball bearings with sealing rings 5d between the moving part and the static part and the coplanar end cover 3d and the end half long shaft and the other end half short shaft, the inner surface of the flexible bearing outer ring inner raceway, the wave generator 11d can produce two sets of concave curved wave, to ensure the coaxial operation of the two, and attached to the motor compartment and the transmission compartment, because the elastic deformation force on the two parallel working back-to-back inner meshing harmonic transmission components in the composite flexible tube cancels out, so there is no axial force on the pair of deep groove ball bearings 5d; the thin-walled flexible tube 9d only has an inner straight tooth ring on the inner surface of both ends and the inner wall of the middle part, and the two flexible bearings are composed of the same equal-diameter ball-cage assembly 10 and the thin-walled inner ring 16 and the thin-walled outer ring 17; the rest of the parallel flexible tube inner meshing harmonic transmission in the motor rotor is the same as that in Figure 1, and will not be described in detail.

[0049] Comparing the left and right sides of Figure 6, it can be seen that their basic functions and advantages have not changed, only the number of components is different, the shape is slightly different, the radial size of the right side is larger than that of the left side, and there are several more interfaces in the force or torque transmission path, so the transmission efficiency of the right side is lower than that of the left side.

[0050] The above describes five preferred embodiments of the present application in detail, and in fact some concepts between them can be used interchangeably, such as the inner wall of the cross section of the composite flexible tube integrated into a herringbone straight tooth ring, which can have multiple forms with the rigid spur gear on the hollow shaft with the same modulus and number of teeth as the axial low stiffness and circumferential high stiffness coupling output, etc.

[0051] It should be understood that those skilled in the art can make many modifications and changes without creative labor according to the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment on the basis of the prior art according to the concept of the present application shall be within the protection scope determined by the claims. Reference

[0052] [1] Wang Yuejun, “Novel Harmonic Gear Transmission Device with External Wave Generator”, Chinese Invention Patent CN 105090372 A.

[0053] [2] Yoshinari Takemura, “DRIVE UNIT WITH REDUCER” U.S. Pat. No. 7,409,891 B2.

[0054] [3] Chen Xiaoyang, Chen Xiangyu, Shen Xuejin, and Qiu Liangwei, “Parallel Type High-efficiency Composite Flexible Tube Harmonic Reducer with Built-in Outer-rotor Motor”, Chinese Invention Patent CN 117847173 A.

Claims

1. A parallel type high efficiency compound flexspline internal meshing harmonic transmission in an electric machine rotor, characterized in that, By means of the outer raceway and inner bevel gear ring of flexible bearing inner ring integrated on the outer surface of both ends, and the straight gear ring integrated on the inner wall of the middle part of the thin-walled composite flexible tube, the anti-symmetric deformation generated by the rotation of two types of rolling wave generators with the same structure size but the end half short shaft and the other end half long shaft coplanar fixed on both ends of the motor hollow inner rotor, through the two internal meshing radial harmonic drive assemblies with the same modulus and tooth number difference working in parallel and back to back, the half of the high-speed rotating torque input to the transmission from the motor inner rotor is amplified in the same proportion respectively; the amplified low-speed rotating torque of the same direction at both ends is superimposed on the constant circle cross section of the composite flexible tube, and the tooth ring on the inner wall of the composite flexible tube and the gear on the hollow shaft constitute a tooth difference free variable stiffness coupling output.

2. The parallel type high efficiency compound flex tube internal meshing harmonic transmission in the motor rotor according to claim 1, characterized in that, The transmission is composed of moving parts, static parts and variable stiffness tooth shape coupling output in radial and axial compact; the moving parts are composed of thin-walled composite flexible tube, two types of different group number bending wave rolling wave generators with the same structure size but the half short shaft at one end and the half long shaft at the other end in the same axial plane fixed on both ends of the motor hollow inner rotor; and the two rigid end covers integrated with bevel gears are fixed on the motor outer stator to form the static parts; the modulus and tooth number difference of the two bevel gear wheels and the inner bevel gear rings at both ends of the composite flexible tube are the same, and the partial bevel gears of the bevel gear wheels and the non-circular bevel gear rings of the composite flexible tube are meshed in the bevel gear way at the inner shrink arc segment of the half short shaft end of the composite flexible tube.

3. The parallel high-efficiency compound flexspline internal-harmonic gear in electric machine rotor according to claim 1 or 2, characterized in that, The straight gear ring is integrated at the middle cross section inner wall of the constant circle of the composite flexible tube, which constitutes the axial low stiffness and circumferential high stiffness coupling output with the rigid herringbone straight gear on the hollow shaft with the same modulus and tooth number; the herringbone tooth intersection cross section must be located on the middle cross section of the composite flexible tube, and the tooth length direction generatrix of the two herringbone straight tooth tips and roots are respectively parallel to the tooth profile generatrix at the maximum inner shrink angle of the inner bevel gear rings at both ends of the composite flexible tube; the inner straight gear ring and the inner bevel gear rings at both ends of the composite flexible tube can have the same tooth type and tooth number, or different tooth type and tooth number; the hollow toothed shaft is supported in the fixed end cover through a pair of angular contact ball bearings to bear the radial and axial external force of the output end.

4. The parallel type high efficiency compound flexspline internal meshing harmonic transmission in the motor rotor according to claim 1 or 2, characterized in that, The first type of rolling wave generator is composed of the same structure size but the half long shaft at one end and the half short shaft at the other end fixed on both ends of the motor hollow inner rotor, the inner surface with flexible bearing outer ring inner raceway, and the wave generator capable of generating two or three groups of equal concave bending waves, which is assembled by two same equal diameter ball-retainer assemblies; the second type of rolling wave generator is composed of the same structure size retainer and the unequal diameter ball group in the retainer hole at both ends of the motor hollow inner rotor, and the thick-walled circular raceway bearing outer ring assembled by two unequal diameter ball groups without circumferential constraint but bearing radial force; the radial and circumferential relative position of the balls in the two unequal diameter ball groups driven by the retainer to revolve remains unchanged, the outer envelope of the ball group is a circle, and the inner envelope can be two or three groups of equal concave bending waves, so the two inner envelopes can ensure that the half long shaft at one end and the half short shaft at the other end are coplanar.

5. The parallel high-efficiency compound flexspline internal harmonical gear in motor rotor according to claim 1 or 2, characterized in that, The tooth length direction generatrix of the bevel gear tooth root must be parallel to the bevel gear outer profile generatrix at the maximum retraction angle of the composite flexible tube, and the tooth length direction generatrix of the bevel gear tooth top must be parallel to the bevel gear outer profile generatrix at the maximum extension angle of the composite flexible tube; the tooth end chamfer is used as the difference between the half long axis length and the half short axis length of the wave generator, and the difference is 1 / 3 or less for the disengagement gap, and 2 / 3 or more for the bevel gear meshing height, so as to increase the meshing area.

6. The parallel type high efficiency compound flexspline internal meshing harmonic transmission in an electric motor rotor according to claim 1 or 2 or 3 or 4 or 5, characterized in that, The moving part of the transmission is supported or suspended by the tooth meshing of the retraction arc segment of the half short axis end of the two end groups of the composite flexible tube, and is coaxial with the two bevel gears, and the axial displacement of the ball-retainer assembly is constrained by the extension and retraction deformation of each group of the two end ports of the composite flexible tube, and the coaxial hollow shaft supported by the angular contact ball bearing can also play an auxiliary constraint function through the variable stiffness tooth profile coupling in the middle section of the composite flexible tube, so that the stator and rotor of the motor do not need to be supported by bearings, and the separation of the motor compartment and the transmission compartment can be solved by the sealing ring between the moving part and the end cover. Of course, the moving part of the transmission can also be radially supported in the two end covers by a pair of deep groove ball bearings with sealing rings, to ensure its coaxial rotation with the two bevel gears, and to separate the motor compartment and the transmission compartment.

7. The parallel high-efficiency compound flexspline internal harmonical gear in motor rotor according to claim 2 or 4, characterized in that, The cylindrical coordinate calculation formula of the two types of rolling wave generators to generate two or three groups of equal bending wave surface of the composite flexible tube with the half long axis end and the half short axis end coplanar is: ； Wherein, R=(r o +r i ) / 2 is the constant circle radius of the middle cross section of the thin-walled composite flexible cylinder, r o is the length of the half long axis of the end face of the composite flexible cylinder, r i is the length of the half short axis of the end face of the composite flexible cylinder, and L is the length of the composite flexible cylinder; for the composite flexible cylinder with the bending wave form group number n, the curvature inflection point value at the half short axis is 1 / n 2 When ε=(R-r i ) / r i is less than the curvature inflection point value, the part of the bevel gear of the non-circular bevel gear ring of the composite flexible cylinder at the inner shrink arc segment of the half short axis end of the two ends of the composite flexible cylinder is engaged in the radial common curvature way; if ε is greater than the curvature inflection point value, the same part of the bevel gear will be engaged in the radial reverse curvature way, and the number of the engaged teeth will be less than that in the common curvature way.

8. The parallel type high efficiency compound flexspline internal meshing harmonic transmission in the motor rotor according to claim 4 or 7, characterized in that, For the second type of rolling wave generator, the bending wave shapes of two or three groups at both ends of the composite flexible tube are rolled and rolled out by the inner envelope shape of each unequal diameter ball group, and the deformation of each ball contact point with the composite flexible tube is always constant, thereby controlling the sequential rotation of each bending deformation point on the composite flexible tube along the circumference, and the deformation of any point is from zero to small to large, then back to small and back to zero, and the cycle is repeated; the radial forces on all balls are borne by the outer ring of the thick-walled circular raceway bearing which is free to rotate, but the resultant force thereon is zero; unlike the first type of rolling wave generator, the cage of this type of rolling wave generator has no radial bending and the radial displacement of each unequal diameter ball is very small, so it can be lubricated with solid oil scheme; without changing r i , by adjusting the ball spacing, or the number of balls, or the ball diameter of the unequal diameter ball group, r o is changed, so that the number of tooth difference between the composite flexible tube and the bevel gear is different, and the reduction ratio is changed.

9. The parallel type high efficiency compound flexspline internal meshing harmonic transmission in electric machine rotor according to claim 1 or 2 or 7, characterized in that, Since the number of teeth of the inner bevel gear ring at the two ends of the composite flexible tube is slightly more than the number of teeth of the bevel gear, in the case that only two groups of orthogonal anti-symmetric deformations are generated in the former, if the difference between the number of teeth is an odd multiple of 2, the two bevel gears need to be circumferentially offset by half a tooth for correct operation; but if the difference between the number of teeth is an even multiple of 2, the latter does not need to be circumferentially offset; in the case that three groups of anti-symmetric deformations are generated in the former, if the difference between the number of teeth is an odd multiple of 3, the two bevel gears also need to be circumferentially offset by half a tooth for correct operation; but if the difference between the number of teeth is an even multiple of 3, the latter does not need to be circumferentially offset; if more groups of anti-symmetric deformations are forced to be generated in the former, the offset installation conditions of the two bevel gears are similar.

10. The parallel high-efficiency compound flexspline internal harmonical transmission in motor rotor according to claim 1 or 2, characterized in that, Even if the moving part and the static part of the transmission are not integrated, but are assembled by separate parts, the name can remove the composite two words, but the function and advantages of the back-to-back parallel type flexible tube type internal meshing harmonic transmission are all in, only the radial size is larger, there are several interfaces in the force or torque transmission path, and the transmission efficiency is reduced.

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