CN112013094A

CN112013094A - Homothetic differential speed reducer

Info

Publication number: CN112013094A
Application number: CN202010038434.6A
Authority: CN
Inventors: 周承岗
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-05-28
Filing date: 2020-01-14
Publication date: 2020-12-01
Also published as: WO2020238816A1

Abstract

The homothetic differential speed reducer is a speed reducer with homothetic differential gear train, its transmission structure is designed by combining difference logic and multiple logic, the size of speed reducing ratio is inversely related to the size of difference value of two contrasted rotating speeds, and said difference value can be infinitely close to zero from positive and negative directions, so that the speed reducing ratio also can be moved toward infinity or infinity, and the speed reducing ratio can not mainly determine how large the multiple of geometric parameter between the components of the transmission wheel set can be, but mainly determines how close the multiple of geometric parameter of two transmission wheel sets can be, so that under the condition of identical size, it can obtain wider output range and larger speed reducing ratio, or under the same speed reducing ratio it has smaller volume or larger load-carrying capacity. On the basis, return difference is reduced by adopting various zero backlash transmission methods, and more excellent comprehensive performance and a larger application range are obtained by matching with other various technical methods.

Description

Homothetic differential speed reducer

Technical Field

The invention relates to a speed reducer, in particular to a speed reducer related to extreme technical characteristics such as ultra-large speed reduction ratio, zero backlash and the like.

Background

The reducer, which is an indispensable transmission device in the field of power machinery, has evolved into a great number of structural types along with the development of industrial civilization in the world for hundreds of years, and is now developing at a high speed in the fields of aerospace, automation, robots and the like, and is also facing a new round of development opportunity, and meanwhile, the reducer also faces higher requirements in various aspects such as transmission ratio, return difference, precision, strength and the like. The prior coaxial speed reducer mainly comprises planets, pinwheel cycloid, rotation vector RV and harmonic wave, the transmission mode is tooth transmission, wherein, as the type with the widest application, the reduction ratio of the planetary speed reducer is determined by the multiple relation of the geometrical parameters such as the diameter, the tooth number and the like of a transmission pair component, the whole transmission structure is also designed according to multiple logic, the basic speed change principle forms the planetary speed reducer, but the basic speed change principle also forms an elbow braking factor which hinders the performance of the planetary speed reducer to be further improved, because of the limitation of material strength and correct meshing conditions, the geometrical parameters of a pinion of the transmission pair can easily reach the minimum limit, the diameter and the tooth number of a bull gear can be increased or the transmission stage number can be increased when a larger transmission ratio is obtained, so that the structure becomes more complex, the volume, the weight and the manufacturing cost are increased, more importantly, the side clearance is gradually increased to increase the return difference, therefore, the method is not suitable for being applied to the fields such as robots and the like which require small volume and high precision. The pin wheel cycloid speed reducer, rotation vector RV reduction gear and harmonic reduction gear have higher transmission precision, but what adopt is few tooth difference speed reduction principle, the size of drive ratio is determined by the tooth number difference and the gear wheel number of teeth, the tooth number difference is too little or the number of teeth of gear wheel is too few all produces the interference easily, also can face the gear wheel when needing big drive ratio big not big enough, the condition that the number of teeth difference is not little enough, for avoiding interfering, the gear often still need the type of repairing and make manufacturing and maintenance inconvenient, in addition, comparatively complicated for planetary reduction gear structure, weak, make load-carrying capacity restricted. Different technical types have advantages and disadvantages, and one type of speed reducer is difficult to simultaneously meet the requirements of multiple aspects.

Disclosure of Invention

The invention mainly aims to provide a speed reducer with a homothetic differential gear train, wherein a transmission structure is designed by combining difference logic and multiple logic, so that the difference of the reduction ratios of two transmission wheel sets is related to the output result of the speed reducer, and a wider output range and a larger reduction ratio are more easily obtained, or the speed reducer has smaller volume or larger load capacity under the same reduction ratio. On the basis, the backlash is reduced by adopting various methods for reducing the backlash, and other various technical methods are matched to obtain more excellent comprehensive performance and a larger application range.

The transmission wheel of the invention comprises a homothetic differential gear train; the homothetic differential gear train with a basic structure is provided with two homothetic transmission wheel sets, each two transmission wheels correspond to each other to form a homothetic group, the two transmission wheels of one group can synchronously rotate, revolve, rotate horizontally or rotate and revolve simultaneously, the homothetic group is called as a synchronous group, the transmission wheels of the other group which are in matched transmission with the synchronous group have coaxial or parallel shafts, one of the transmission wheels is fixedly installed as a stator, the other transmission wheel is rotatably installed as a rotor, and the homothetic group is called as a differential group; the synchronous group and the differential group are directly driven or driven through an intermediate wheel; the homothetic differential gear train takes the synchronous set as an input element and the rotor as an output element to carry out speed reduction transmission and can also carry out acceleration transmission in reverse; the type of the transmission wheel is a gear, a chain wheel, a belt wheel, a flexible wheel, a friction wheel or a magnetic wheel.

The invention is characterized in that a synchronous set and a differential set are in direct transmission, the differential set is two coaxial outer rings or sun wheels, the synchronous set is a composite planet wheel or a flat rotating wheel set, a middle shaft is a power shaft, the synchronous set and the middle shaft are connected in a way that a rotating arm or an eccentric wheel is fixedly connected with the middle shaft, and the composite planet wheel is rotatably arranged on the rotating arm or the flat rotating wheel set is rotatably connected with the eccentric wheel; or the middle shaft and the composite planet wheel or the flat rotating wheel are connected through a preceding-stage speed reducing mechanism; or the middle shaft is a hollow shaft, and the composite planet wheel is directly rotatably arranged on the non-coaxial position of the middle shaft.

The homothetic differential gear train of the invention adopts a synchronous group grouping backlash eliminating mode to drive, synchronous group units are divided into two groups which respectively work only in different directions, when one group works, the other group is at a working position which is closer to the other direction than the group, and the specific methods include but are not limited to a gear tooth dislocation method, an overrunning clutch method and a reverse circumferential force method.

The homothetic differential gear train adopts the prior anti-backlash gear to carry out zero backlash transmission, and the homothetic differential gear train comprises but is not limited to a non-standard tooth profile gear, a layered staggered gear and an axial staggered herringbone gear, or adopts an installation mode of pre-pressure in the meshing direction to eliminate backlash.

The two transmission wheels of the differential group of the invention are in axially different positions and do not occupy the radial outer space of each other, or no other component occupies the radial outer space of the stator or rotor, so that their transmission points can be arranged in a more central position in the overall structure, thus making the backlash return angle smaller.

The invention is characterized in that the transmission wheel is axially transmitted on a central shaft, two homothetic wheels of a synchronous set are combined into a step wheel, a differential set is mutually nested in the radial direction, and a rotor directly uses a stator as a slewing bearing or separates a supporting device with motion drag reduction effect or axial force bearing effect.

The invention is provided with an axial position adjusting device and a control device thereof, can be used for adjusting the backlash of the driving wheel, or balancing the axial force of the driving wheel, or adjusting the friction force of the driving wheel, and can be manually or automatically controlled.

The invention is provided with an integrated power device, an input part of the homothetic differential gear train is also an output part of the power device, or a stator of the homothetic differential gear train is directly arranged on a fixed part of the power device, or the homothetic differential gear train and the power device are radially nested and distributed.

The homothetic differential gear train comprises an asymmetric gear, wherein the tooth profile of the gear is in a left-right asymmetric shape, or the left tooth surface and the right tooth surface of the gear have different mechanism structures, roughness or physical properties.

The same homothetic differential gear train of the invention uses gears with different modules in a mixed way, so that the transmission gear train and even the whole homothetic differential gear train have richer transmission ratio selection under the same magnitude size.

Positive effect

The reduction ratio of the homothetic differential gear train is inversely related to the difference between two contrast rotating speeds of the differential group, and the difference can be infinitely close to zero from positive and negative directions, so the reduction ratio of the homothetic differential gear train can also tend to be infinite or infinitesimal, the reduction ratio can not determine how large the times of the geometric parameters between the components of one transmission wheel group are but determine how close the times of the geometric parameters of the two transmission wheel groups are, the restriction degree of the size of the transmission wheel on the reduction ratio is weakened, a wider output range and a larger reduction ratio can be obtained under the condition of equivalent size, or smaller volume or larger load capacity can be obtained under the same reduction ratio. Taking a basic structure as an example, in a homothetic differential gear train formed by two transmission gear sets of a 109-tooth pair 37 teeth with a modulus of 0.5 and a 91-tooth pair 31 teeth with a modulus of 0.6, the 37 teeth and the 31 teeth are synchronous sets, and the 109 teeth and the 91 teeth are differential sets; the synchronous group is used as an input element to drive the differential group in a driving revolution mode, 91 teeth are fixed, and 109 teeth are used as output elements; the synchronous group rotates for 2.94 circles in each 1 revolution, the angular displacement difference of 91 teeth and 109 teeth is only 0.0012 circles in each 1 revolution, and the total speed reduction ratio of the whole gear train is 283: 1, a larger reduction ratio is obtained under the condition of less teeth, and the limit is far not reached, which is difficult to be achieved by other reducers under a single-stage reduction structure; in conventional applications, the reduction ratio is generally less than 100, the transmission wheels require fewer teeth, the same module can be maintained to make the gear volume smaller, and a larger module can be used to make the gear teeth larger to improve the load capacity. The homothetic differential gear train has at least four driving wheels of two driving wheel sets to participate in transmission, the number of the driving wheels is more, but the transmission ratio range is greatly expanded, because the number of the driving wheels is more, the variables influencing the output result are more, and the selectable output result is richer due to the application of different moduli, so the application range is wider. In general, the longer the transmission chain, the worse the precision, but because two transmission wheel sets of the homodromous differential gear train are in homodromous relationship, the total amount of the radial clearance of the gear in the whole size and the difficulty of precision control are not increased, in some embodiments, such as a structure that a synchronous set and a rotor move in the same direction, the gear backlash influencing the backlash size is only from the transmission wheel set with the larger backlash, and the backlash link of one transmission wheel set can be only one, when a transmission point is arranged at a position with a larger diameter on the basis of the shortest transmission chain or a zero backlash transmission mode is combined, and the high rigidity characteristic of the gear transmission is combined, the backlash can be controlled in a small range, which is an important characteristic that an excellent speed reducer should have. The transmission wheel of the homothetic differential gear train can achieve the performances of large reduction ratio, zero backlash and the like only by a standard involute gear, the system has the advantages of reliable transmission, strong impact resistance, balanced stress, long service life, low manufacturing cost and the like, and when the embodiment of the friction wheel or the magnetic wheel is adopted, the structure is simpler, and the system is valuable in application occasions of low precision, low load, maintenance-free, flexible silence, miniature light weight, overload protection and the like. When the homothetic differential gear train adopts a transmission structure with intersecting shafts or staggered shafts, the backlash can be adjusted through the displacement between the meshing pairs in the axial direction or the offset direction, the differential groups can be radially overlapped to save space, and the distribution radius of the synchronous groups can be smaller than that in a parallel shaft structure, so that the radial size and the motion inertia are smaller. In the zero backlash transmission embodiment, one of the left tooth surface and the right tooth surface is a working surface, and the other is a non-working surface, and the asymmetrical tooth profile shape and different materials, processing methods or processing precisions are adopted in a targeted manner to enable the tooth surfaces to have different mechanism structures, roughness or physical properties, so that different tooth surfaces can meet different requirements or save cost. The reduction transmission system is integrated with the power device, so that the whole structure is more compact, and the reduction transmission system is beneficial to simplifying the structure, reducing the volume and lowering the cost.

Drawings

FIG. 1 is an embodiment in which the synchronizing group is a planetary gear set;

FIG. 2 is an embodiment in which the synchronization group is a sun gear;

FIG. 3 is an embodiment in which the synchronization group is a level wheel;

FIG. 4 is a plan view of a two-stage reduction embodiment of the rotatable wheels;

FIG. 5 is a planetary secondary reduction embodiment;

FIG. 6 is a hollow shaft embodiment;

FIG. 7 illustrates a first method for eliminating backlash of synchronization packets;

FIG. 8 is a second synchronization group packet anti-backlash method;

FIG. 9 illustrates a third method for anti-backlash of the sync group;

FIG. 10 is a radially nested embodiment of bevel gears;

fig. 11 shows an integrated embodiment of the reduction mechanism and the power unit.

Detailed Description

The transmission wheel of the invention comprises a homothetic differential gear train; the homothetic differential gear train with a basic structure is provided with two homothetic transmission wheel sets, each two transmission wheels correspond to each other to form a homothetic group, the two transmission wheels of one group can synchronously rotate, revolve, rotate horizontally or rotate and revolve simultaneously, the homothetic group is called as a synchronous group, the transmission wheels of the other group which are in matched transmission with the synchronous group have coaxial or parallel shafts, one of the transmission wheels is fixedly installed as a stator, the other transmission wheel is rotatably installed as a rotor, and the homothetic group is called as a differential group; the synchronous group and the differential group are directly driven or driven through an intermediate wheel; the homothetic differential gear train takes the synchronous set as an input element and the rotor as an output element to carry out speed reduction transmission and can also carry out acceleration transmission in reverse; the type of the transmission wheel is a gear, a chain wheel, a belt wheel, a flexible wheel, a friction wheel or a magnetic wheel. The homothetic transmission wheel set refers to two transmission wheel sets, wherein the transmission wheel of one transmission wheel set and the transmission wheel of the other transmission wheel set correspond to each other in mounting direction or transmission relationship, a common rotating shaft or a rotating shaft which is parallel to each other is arranged, at least one of the transmission wheels in the respective sets is in the same transmission direction, for example, both the transmission wheels are sun wheels, planet wheels or outer rings, or the transmission objects are sun wheels, planet wheels or outer rings; the transmission wheels corresponding to each other are the same-position wheels, the corresponding mode of the same-position wheels can be that the driving wheels correspond to the driving wheels and the driven wheels correspond to the driven wheels, or the driving wheels and the driven wheels correspond to each other in a crossed manner. In the inventive co-located transmission wheel set, there is a group of co-located wheels moving synchronously, also called as synchronized wheels, their combination is a synchronized group, and they revolve, rotate or revolve and rotate simultaneously at the same or opposite angular velocity, the specific form of combination includes but is not limited to stepped wheel, coaxial wheel, the other two co-located wheels moving asynchronously, called as differential wheel, one of which can rotate, called as rotor, the other fixed installation as reference system, called as stator, and their combination is a differential group. Referring to fig. 1, a middle shaft 6 is rotatably connected with a base 12 through a shaft sleeve 13, a rotating arm 5 is fixedly connected with the middle shaft 6 and is rotatably connected with a rotating shaft 4 through a bearing 3, a planet wheel 2 and a planet wheel 10 are fixedly connected into a synchronous set through the rotating shaft 4, the synchronous set can synchronously rotate and revolve, and more than two synchronous sets are uniformly distributed in the circumferential direction; the outer ring 9 is fixedly arranged on the base 12, the outer ring 1 takes a bearing 8 fixed on the end face of the outer ring 9 as a rotary support, and the outer ring 1 can also only take the planet wheel 2 as a floating support; the outer ring 1 and the outer ring 9 form a differential group by taking the middle shaft 6 as a common shaft center, and are respectively transmitted with the planet wheels 2 and the planet wheels 10 to form two homothetic transmission wheel sets, namely a homothetic differential gear train with a basic structure. When power is input from the middle shaft 6 to drive the synchronous set to revolve, the rotating speed of the outer ring 1 with the outer ring 9 as a reference is positively correlated with the difference of the transmission ratios of the two homothetic transmission wheel sets, the transmission ratio of the whole homothetic differential gear train is negatively correlated with the rotating speed of the outer ring 1 with the outer ring 9 as the reference, the smaller the difference of the transmission ratios of the two transmission wheel sets is, the larger the value of the transmission ratio of the whole homothetic differential gear train is, and when the difference of the transmission ratios of the two transmission wheel sets is zero, the transmission ratio is infinite or infinitesimal. The homothetic differential gear train performs speed reduction transmission by taking the outer ring 1 as an output element, or performs acceleration transmission by taking the outer ring 1 as an input element, and different transmission ratios can be obtained by changing the difference of the transmission ratios of the two transmission wheel sets. In order to balance the forces on the bearing 3, a sun wheel, which is movably connected to the central shaft 6, may be provided to balance the radial forces on the

planet wheels

2 and 9. The types of drive wheels that can be used in the co-located differential gear train include, but are not limited to, gears, sprockets, pulleys, flexspline, friction wheel, magnetic wheel, and other closed-turn flexures that function in a configuration including, but not limited to, an inner ring, an outer ring, a sun wheel, a planet wheel, a roller wheel, a flat wheel, and a vector of rotation RV wheel. When the drive wheels are gears, of the type including but not limited to spur, helical, bevel or face gears, and of the type including but not limited to involute, circular arc, cycloid or parabola, different sets of drive wheels preferably have the same modulus, but may have different moduli to achieve a more suitable drive ratio. In the embodiment of fig. 1, the synchronizing wheel and the differential wheel are directly driven, or an intermediate wheel may be provided for driving, as in the embodiment shown in fig. 2, the sun wheel 20 and the sun wheel 21 are fixedly connected with the middle shaft 22 to form a synchronizing set, and the intermediate wheel set formed by fixedly connecting the intermediate wheel 17 and the intermediate wheel 18 is used for driving the outer ring 15 and the outer ring 16 of the differential set. Fig. 3 shows an embodiment in which the synchronizing group is a flat wheel-the flat wheel 26 and the flat wheel 32 are rotatably connected by a plurality of small cranks 27 and by a sleeve 28 and an eccentric 30 to a central shaft 29, thus forming a synchronizing group which can be eccentrically rotated flat and which is in transmission with the outer ring 25 and the outer ring 31 of the differential group, respectively. The homothetic differential gear train can also be provided with a speed change device to form a two-stage speed change structure, for example, the embodiment shown in fig. 4, the outer ring 35 and the outer ring 39 are differential groups, the flat rotating wheel 36 and the flat rotating wheel 41 are synchronous groups, the small crank 37 rotationally connected with the flat rotating wheel 36 and the flat rotating wheel 41 is connected with the central shaft 38 through

speed reducing wheels

40 and 42, for example, the embodiment shown in fig. 5, the outer ring 43 and the outer ring 49 are differential groups, and the planet wheels 44 and the planet wheels 50 form a synchronous group and are connected with the central shaft 47 through speed reducing wheel groups 45. In the case of multiple output results, the homothetic differential gear train may be of composite structure with multiple transmission wheel sets, synchronous sets, differential sets, stators or rotors, and different working combinations may be selected by switching the output gears.

The synchronous group and the differential group are in direct transmission, the differential group is two coaxial outer rings or sun wheels, the synchronous group is a compound planet wheel or a flat rotating wheel group, a middle shaft is used as a power shaft, the synchronous group and the middle shaft are connected in a way that a rotating arm or an eccentric wheel is fixedly connected with the middle shaft, the compound planet wheel is rotatably arranged on the rotating arm or the flat rotating wheel group is rotatably connected with the eccentric wheel, as in the embodiment of the previous figures 1 and 3; or, in order to reduce the rotating speed of the assembly or the motion inertia of the system, the central shaft and the compound planet wheel or the flat wheel are connected through a preceding stage speed reducing mechanism, as in the embodiment of the previous fig. 4 and 5; alternatively, the central shaft is a hollow shaft, and the compound planetary gear is directly and rotatably mounted at a non-central position of the central shaft, as shown in fig. 6, the synchronizing group is a compound planetary gear consisting of a planetary gear 52 and a planetary gear 55, and is directly and rotatably mounted on a non-coaxial shaft of a hollow shaft 56, and the hollow shaft 56 is connected with an output element at the same radial position on the power plant, or is an output element of the power plant itself.

Referring to fig. 7, the co-located differential gear train is driven by adopting a synchronous group grouping anti-backlash manner — an outer ring 57 and an outer ring 58 depicted by a dotted line are differential groups, the outer ring 57 is a stator, the outer ring 58 is a rotor, the planetary wheels 59 and the planetary wheels 60 depicted by a solid line form a compound planetary wheel as a synchronous group; planet wheels 59 transmit the outer ring 57, planet wheels 60 transmit the outer ring 58, the rotation direction of the outer ring 58 is opposite to the revolution direction of the compound planet wheels by selecting the magnitude relation of the transmission ratio of the two transmission wheel sets, the working surfaces of the outer ring 57 and the outer ring 58 face oppositely at the same time, and the working surfaces of the two transmission wheels of the same compound planet wheel unit face oppositely; more than two composite planet wheel units are divided into two groups, for the purpose of stress balance, the number of the composite planet wheel units in each group is preferably even, and the composite planet wheel units are uniformly distributed in the same group in the circumferential direction or uniformly mixed; the relative angles of the two driving wheels of the compound planetary wheel units of different groups are different, so that the planetary wheels 59 of one group work only in the clockwise direction, the planetary wheels 60 work only in the anticlockwise direction, the planetary wheels 59 of the other group work only in the anticlockwise direction, the planetary wheels 60 work only in the clockwise direction, when one group works, the other group is in a working position which is closer to the other direction than the group, and is not in contact with the working tooth surfaces of the differential group or is in pressure-free contact with the non-working tooth surfaces of the differential group, or a small backlash which does not influence normal transmission can be reserved, and therefore zero backlash transmission can be realized by using common gears. Zero backlash in the drive means that there is not absolutely no backlash, but that the backlash approaches the minimum backlash under ideal conditions when the drive is running normally. The synchronous grouping backlash can also be realized by an overrunning clutch method shown in fig. 8, wherein fig. 8 is added with an overrunning clutch 85, a magnetic ring 86 and a planet carrier 87 on the basis of fig. 5; by selecting the magnitude relation of the transmission ratios of the two transmission wheel sets, the rotation direction of the outer ring 43 is the same as the revolution direction of the compound planet wheel, the working surfaces of the outer ring 43 and the outer ring 49 face the same at the same time, and the working surfaces of the two transmission wheels of the same compound planet wheel unit face the same; the rotating shaft of each compound planet wheel is rotationally connected with the planet carrier 87 and is provided with an overrunning clutch 85, the magnetic ring 87 is fixed on the ring 47, and the outer ring of the overrunning clutch 85 is a magnetic ring which can be driven by the magnetic force action with the magnetic ring 86; a plurality of composite planet wheel units are divided into two groups A and B, more than two groups are suitable for each group, and the installation directions of the overrunning clutches 85 of the two groups are opposite; the transmission ratio of the transmission wheel 48 to the transmission wheel 45 is greater than that of the overrunning clutch 85 to the magnetic ring 86, when the middle shaft 47 drives the transmission wheel 48 to rotate towards one direction, the overrunning clutch 85 of the group A is in a separation state, the state of the compound planetary wheel unit is not influenced, and the overrunning clutch 85 of the group B is in a combination state, so that the compound planetary wheel unit connected with the overrunning clutch 85 leaves a working position at a rotating speed which is faster than the working rotating speed, finally reaches the working position in the other direction and keeps a preparation state, at this time, the magnetic force between the outer ring of the overrunning clutch 85 and the magnetic ring 86 on the overrunning clutch is far smaller than the rigid resistance between the transmission wheel sets to mutually slip and rotate, when the middle shaft 47 drives the transmission wheel 48 to rotate reversely, the group B works, the group A is in the preparation state, and therefore, the backlash between the transmission wheel 48; the positions of the magnetic ring 86 and the overrunning clutch 85 can be interchanged, and the outer rings of the magnetic ring 86 and the overrunning clutch 85 can be replaced by friction rings; the backlash between the sync and differential sets of the embodiment of fig. 1 can be eliminated by the same principle. The 'reverse circumferential force method' can also be adopted, as shown in fig. 9, the compound planetary wheel units 88 of the same group are arranged in pairs and opposite to each other, and are meshed with the gears 89 at the two ends of the reed 90, the gears 89 are tightened towards the center under the action of the reed 90, and the compound planetary wheel units 88 of different groups are respectively applied with reverse circumferential forces to be located at working positions in different directions. The specific method of implementing packet anti-slot is not limited to the above list.

In addition to the synchronous grouping anti-backlash mode, the homothetic differential gear train can also adopt the existing anti-backlash gears to perform zero backlash transmission, and the homothetic differential gear train comprises but is not limited to non-standard tooth profile gears, layered staggered gears and axial staggered herringbone gears. The gear teeth of the gear with the non-standard tooth profile can be transmitted with zero backlash after being specially modified and ground; the layered staggered gear is a cylindrical straight gear, a cylindrical helical gear or a bevel gear, and is axially divided into two thin-plate gears which are mutually staggered in the circumferential direction by a small angle, the bevel gear can also be radially layered, and the layered staggered gear is matched with a non-layered gear to reduce the backlash on the whole tooth width; the axial dislocation herringbone gear refers to that two correctly meshed herringbone helical gears are displaced in the axial direction, so that one section of two sections of the herringbone gear teeth is withdrawn from the working position, and the backlash on the whole tooth width is reduced. In addition, an installation mode of applying pre-pressure in the meshing direction can be adopted, no side gap is left during installation, and the device is particularly suitable for a cycloidal gear and a pin wheel meshing pair.

Referring to fig. 1, the outer ring 1 and the outer ring 9 of the differential set are at different positions in the axial direction, do not occupy the radial outer space of each other, the connection position between the outer ring 1 and the outer ring 9 is in the end face direction, and no housing or other components occupy the radial outer space of the outer ring 1 or the outer ring 9, so that the transmission points can be arranged at positions far from the center in the whole structure, and the backlash return angle is small.

As in the embodiment of fig. 10, the driving wheel is a bevel gear, a face gear or a helical gear which drives in the axial direction, and may also be a friction wheel or a magnetic wheel, and the differential group is composed of an outer ring 67 and an inner ring 69, one of which is a stator and the other of which is a rotor; the synchronous group is formed by fixedly connecting a driving wheel 61 and a driving wheel 63; the rotating shaft 62 is rotatably connected with a connecting block 64 fixed on a middle shaft 65, and the middle shaft 65 is rotatably connected with an inner ring 69; the outer ring 67 and the inner ring 69 may be supported axially via a sleeve 68, and one of the rotors may be directly used as a slewing bearing or one of the stators may be used as a slewing bearing, or the sleeve 68 may be a composite structure. This radially nested configuration saves axial space and for other design purposes can also be arranged opposite each other on both axial sides of the synchronization group.

Referring to fig. 10, the threaded sleeve 66 can move axially along the external thread of the central shaft 65 when rotating in different directions, and can be used to adjust the backlash of the gears, or to balance the axial force of the driving wheel, or to adjust the friction force of the driving wheel. The threaded sleeve 66 is also connected with a locking device, a manual control device or an automatic control device. The threaded sleeve 66 is a position adjusting device, and the technical type thereof and the control device matched with the threaded sleeve are not limited to a threaded structure, and the technical types thereof can be adopted by the position adjusting device and the control device matched with the position adjusting device include but not limited to mechanical devices such as a lever, a pull rope, an eccentric wheel, a wedge block and the like, and liquid, gas, sound, light, magnetism, electricity, heat or the combination of the above various types.

To improve the integration, the homothetic differential gear train can be integrated with an electric motor, an engine or other types of power plants, the input part of the homothetic differential gear train is also the output part of the power plant, or the stator of the homothetic differential gear train is directly mounted on the fixed part of the power plant, or the homothetic differential gear train and the power plant are nested and distributed in the radial direction. As in the embodiment of fig. 11, the differential group is composed of an outer ring 70 and an outer ring 78, the synchronous group is composed of

planetary gears

72 and 80 fixedly connected by a rotating shaft 73, the rotating shaft 73 is rotatably connected by a bearing 71 with a rotating arm 75 fixed on an outer rotor 76 of the motor, and a stator 77 of the motor and the outer ring 78 of the differential group are both fixed on a base 81.

When a synchronous component group backlash eliminating structure is adopted or layered staggered gears and axial staggered herringbone gears are adopted for transmission, the same gear tooth of some transmission wheels only bears load in one direction, a pressure bearing face needs to have higher hardness and better heat resistance, wear resistance and friction reduction performance, a non-pressure bearing face needs to have higher compressive strength and toughness, and in order to enable different gear faces to respectively meet different requirements, an asymmetric tooth profile shape can be adopted, for example, a working face is taken as a standard parameter, a non-working face is thickened in the circumferential direction and provided with oil grooves, or different surface materials or processing methods are respectively adopted, so that the non-pressure bearing face and the non-pressure bearing face have different mechanism structures, roughness or physical properties.

The gears with different modules are mixed in the same homothetic differential gear train, and different transmission wheel sets adopt different modules, so that the transmission wheel sets and even the whole homothetic differential gear train have richer transmission ratio selection under the same magnitude size.

Claims

1. The homothetic differential speed reducer comprises an input element, an output element and a transmission wheel, is directly arranged on other objects or is also provided with a base or a middle shaft, and is characterized in that the transmission wheel comprises a homothetic differential gear train; the homothetic differential gear train with a basic structure is provided with two homothetic transmission wheel sets, each two transmission wheels correspond to each other to form a homothetic group, the two transmission wheels of one group can synchronously rotate, revolve, rotate horizontally or rotate and revolve simultaneously, the homothetic group is called as a synchronous group, the transmission wheels of the other group which are in matched transmission with the synchronous group have coaxial or parallel shafts, one of the transmission wheels is fixedly installed as a stator, the other transmission wheel is rotatably installed as a rotor, and the homothetic group is called as a differential group; the synchronous group and the differential group are directly driven or driven through an intermediate wheel; the homothetic differential gear train takes the synchronous set as an input element and the rotor as an output element to carry out speed reduction transmission and can also carry out acceleration transmission in reverse; the type of the transmission wheel is a gear, a chain wheel, a belt wheel, a flexible wheel, a friction wheel or a magnetic wheel.

2. The homothetic differential reducer according to claim 1, wherein the differential group is directly driven between the synchronous group and the differential group, the differential group is two coaxial outer rings or sun wheels, the synchronous group is a compound planetary wheel or a flat-turn wheel group, the central shaft is a power shaft, the connection between the synchronous group and the central shaft is in a manner that a rotating arm or an eccentric wheel is fixedly connected with the central shaft, the compound planetary wheel is rotatably mounted on the rotating arm or the flat-turn wheel group is rotatably connected with the eccentric wheel; or the middle shaft and the composite planet wheel or the flat rotating wheel are connected through a preceding-stage speed reducing mechanism; or the middle shaft is a hollow shaft, and the composite planet wheel is directly rotatably arranged on the non-coaxial position of the middle shaft.

3. The speed reducer of claim 2, wherein the speed reducer is driven by a synchronous group backlash method, the synchronous group units are divided into two groups, and the two groups work in different directions respectively, and when one group works, the other group is in a working position closer to the other direction than the other group, and the working positions are determined by methods including but not limited to a gear tooth dislocation method, an overrunning clutch method and a reverse circumferential force method.

4. The homothetic differential reducer of claim 2, wherein the homothetic differential gear train uses existing anti-backlash gears to perform zero backlash transmission, including but not limited to non-standard tooth profile gears, layered offset gears, axially offset herringbone gears, or mesh direction pre-compression mounting to eliminate backlash.

5. A reduction gear according to claim 1, 2, 3 or 4, characterized in that the two transmission wheel portions of the differential set are at axially different positions, not occupying the radial outer space of each other, or no other component occupies the radial outer space of the stator or rotor, so that their transmission points can be arranged at more remote positions in the overall structure, thus making the backlash return angle smaller.

6. A speed reducer according to claim 1, 2, 3 or 4, characterized in that the drive wheels drive in the axial direction of the central shaft, the two co-located wheels of the synchronizing group are combined into a step wheel, the differential group is nested radially with each other, the rotor is directly supported by the stator as a rotary support, or via a support device having a motion-drag-reducing action or bearing the axial force.

7. A reduction gear according to claim 6, wherein the differential gearing is provided with means for adjusting the axial position and means for controlling the same, which means can be used to adjust the backlash of the drive wheels, or to balance the axial forces of the drive wheels, or to adjust the friction of the drive wheels, and which means can be controlled manually or automatically.

8. A reduction gear unit according to claim 1, 2, 3, 4 or 7, characterized by an integrated power unit, wherein the input member of the parity differential gear train is also the output member of the power unit, or wherein the stator of the parity differential gear train is mounted directly on a stationary member of the power unit, or wherein the parity differential gear train and the power unit are nested radially.

9. The reduction gear of claim 8, wherein the homothetic differential gear train comprises an asymmetric gear having a tooth profile with left and right asymmetric shapes, or having left and right tooth surfaces with different mechanical structures, roughness or physical properties.

10. A reduction gear according to claim 1, 2, 3, 4, 7 or 9, wherein gears of different modules are used in a single homothetic differential gear train, so that the gear train and thus the whole homothetic differential gear train have a richer choice of transmission ratio at the same order of magnitude.