CN114607756A - Planetary gear reducer for robot - Google Patents

Abstract

The invention discloses a planetary gear reducer for a robot, which solves the problems of increased span of a planetary shaft and weakened rigidity caused by larger axial size of the conventional planetary gear reducer. The reducer adopts the retainer ring for holes to axially position the planet wheel of the first-stage planetary gear reduction mechanism, the planet wheel bearing of the current-stage planet carrier is axially positioned, the planet carrier of the previous stage is axially positioned through the first external teeth of the sun wheel of the next stage, and the planet wheel and the planet carrier of the same stage are directly contacted to realize mutual axial positioning.

Description

Planetary gear reducer for robot

Technical Field

The invention relates to a gear transmission device, in particular to a planetary gear reducer for a robot.

Background

The existing robot speed reducer generally adopts an RV speed reducer structure, and the RV speed reducer has the advantages of small size and large speed reduction ratio, but relatively speaking, due to the adoption of a cycloid gear structure, the robot speed reducer is difficult to machine, high in cost, low in transmission efficiency and poor in precision retentivity. The planetary gear reducer is superior to the RV reducer in the aspects of cost, efficiency, precision retentivity and the like.

For example: chinese patent, application number is: CN200710068194.9 discloses a closed planetary gear reducer, which is a three-stage planetary gear structure as shown in fig. 1, wherein the input end high-speed stage sun gear 14 contacts with the casing (actually, the end cover 18) through the bearing 19 for axial positioning, and the output end low-speed stage planetary shaft 5 contacts with the output flange (i.e., the three-stage planetary carrier 34) for axial positioning. The sun wheels at all levels are in contact positioning with each other; each planet carrier is axially positioned through a snap spring on the sun gear and the end surface of the gear tooth of the sun gear; the planet wheel shaft is axially fixed on the planet carrier through a shaft shoulder and a clamp spring; the planet wheel is positioned on the planet shaft through one side of the bearing of the planet shaft, and the other side of the bearing is positioned on the planet carrier.

However, the planetary gear reducer with the above structure has the following problems:

1. the snap springs are adopted for axial positioning in a large number, so that the axial size is occupied, the span of the planet shaft is enlarged, the rigidity is weakened, and the situation that some scenes with harsh requirements on the use space cannot be met due to the large axial size is achieved.

2. A deep groove ball bearing is adopted between a low-speed-stage planet carrier serving as an output end of the planetary gear reducer and an inner gear shell, but the deep groove ball bearing is mainly used for bearing radial loads, so that the bearing capacity of the planetary gear reducer to axial and bending moment loads is reduced. In some structures, the deep groove ball bearing is replaced by a double-row angular contact ball bearing, but the bearing is adopted, so that the space occupied by the whole speed reducer is too large, and the power density of the speed reducer is reduced.

3. The planet wheel bearings between the planet wheels and the planet shafts in all stages of the planet gear speed reducing mechanisms are needle roller bearings, and the needle roller bearings are in line contact with inner holes of the planet wheels and outer circles of the planet shafts after assembly is completed.

However, due to manufacturing errors (cylindricity errors of the three parts, i.e., the roller pin, the inner hole of the planet wheel and the excircle of the planet shaft), the manufacturing errors can actually become point contacts close to one end of the axial direction of the roller pin, so that radial loads borne by the roller pin are not uniformly distributed along the axial direction, further, the friction force of the roller pin along the axial direction is not uniform, the axis of the roller pin is not perpendicular to the moving direction, the friction resistance can be increased due to the inclination, the dragging phenomenon is generated, and the roller pin is enabled to be out of work quickly.

In addition, after the speed reducer is loaded, when the planet carrier serving as the low-speed output end resists the output torque, the torsion load which needs to be carried is far greater than that of the other end (input end), so that the planet carrier serving as the low-speed output end generates torsion deformation, the planet shaft generates bending deformation, and the deformation further destroys the linear contact of the needle bearing.

The two factors greatly reduce the transmission efficiency of the needle bearing, so that the needle bearing is very easy to lose efficacy, the service life is shortened, and the needle bearing is the link which is most easy to lose efficacy and damage in the speed reducer.

Disclosure of Invention

The invention provides a planetary gear reducer for a robot, aiming at solving the problems that the span of a planetary shaft is increased and the rigidity is weakened due to larger axial size of the conventional planetary gear reducer, the problems that a deep groove ball bearing or a double-row angular contact ball bearing is adopted between a planetary frame and an inner gear shell at the output end, and the problem that a planetary gear bearing is easy to lose efficacy when a needle bearing is adopted.

The specific technical scheme of the invention is as follows:

a planetary gear reducer for a robot comprises an inner gear shell and N-stage planetary gear speed reducing mechanisms which are sequentially arranged along the axial direction of the inner gear shell; n is more than or equal to 2; each stage of planetary gear speed reducing mechanism comprises a sun gear, a planetary carrier and a planetary shaft;

the improvement is as follows:

a planet wheel of the 1 st-stage planetary gear speed reducing mechanism is axially positioned by a retainer ring through a hole clamped in the inner gear shell;

in the 2 nd to N-stage planetary gear speed reducing mechanisms, the sun gear is provided with a first external tooth and a second external tooth, and the tooth height of the first external tooth is larger than that of the second external tooth; the first external teeth are meshed with the planet wheel of the current stage, and the second external teeth are in key connection with the planet carrier of the previous stage; the end face of the previous-stage planet carrier is in contact with the end face of the first external tooth on the current-stage sun gear, and simultaneously forms a micro gap with the end face of the current-stage planet gear;

the planet shaft of each stage of planetary gear speed reducing mechanism is in interference fit with the planet shaft mounting hole on the planet carrier, and the planet gear of the Nth stage of planetary gear speed reducing mechanism is in mutual contact with the planet carrier to realize the axial positioning of the planet gear in the Nth stage of planetary gear speed reducing mechanism;

in the 1-N-stage planetary gear speed reducing mechanism, S first inner ring outer raceways are axially arranged on the outer surface of a planetary shaft in a planetary wheel bearing mounting hole side by side, S is more than or equal to 2, and a plurality of first steel balls are arranged between each first inner ring outer raceway and the hole wall of the planetary wheel bearing mounting hole along the circumferential direction; first steel balls arranged in every two adjacent first inner ring outer raceways are arranged in a staggered manner in the circumferential direction, so that a planetary wheel bearing of the N-stage planetary gear speed reducing mechanism is formed; one side of the planet wheel bearing mounting hole, which is close to the planet carrier, is provided with an arc-shaped groove which protrudes inwards and is used for axially positioning the first steel ball;

the planet carrier of the Nth-stage planetary gear speed reducing mechanism is in rotary connection with the inner gear shell through at least one row of contact type ball bearing structures, and meanwhile, the contact type ball bearing structures realize the axial positioning of the planet carrier in the Nth-stage planetary gear speed reducing mechanism;

the contact type ball bearing structure comprises M second inner ring outer raceways which are arranged on the outer surface of a planet carrier of the Nth-stage planetary gear speed reducing mechanism along the axial direction, and M second outer ring inner raceways which are in one-to-one correspondence with the M second inner ring outer raceways are arranged on the inner wall of the inner gear shell along the axial direction; m is more than or equal to 1;

m steel ball mounting raceways are formed between the M second inner ring outer raceways and the M second outer ring inner raceways; a plurality of second steel balls are arranged in each steel ball mounting roller path along the circumferential direction;

at least one axial hole is formed in a planet carrier of the Nth-stage planetary gear speed reducing mechanism, M ball filling holes are formed in the positions, corresponding to the outer raceway of the second inner ring, of the axial holes, and anti-falling-out structures for preventing balls from falling out are arranged in the ball filling holes;

a key groove used for being connected with the output end of an external motor is arranged in a central through hole of a sun gear of the 1 st-stage planetary gear speed reducing mechanism.

Further, each stage of the sun wheel is provided with a central through hole; a positioning through hole for mounting a motor is formed in the center of a planet carrier of the Nth-stage planetary gear speed reducing mechanism, and a key groove is formed in a central through hole of a sun gear in the 1 st-stage planetary gear speed reducing mechanism.

Furthermore, a planet carrier of the Nth-stage planetary gear speed reducing mechanism is also provided with a limiting hole, and the limiting hole is communicated with the ball filling hole; and a limiting device for preventing the anti-falling structure from moving is arranged in the limiting hole.

Furthermore, the limiting hole is a screw hole parallel to the axial hole, and the limiting device is a fastening screw.

Further, when M is 1: the steel ball mounting raceway comprises four sections of eccentric circular arcs, each section occupies 1/4 of the section perimeter, and the second steel ball is in point contact with the four sections of circular arcs of the steel ball mounting raceway.

Further, when M is 2,

the first steel ball mounting raceway comprises four sections of eccentric circular arcs, and each section of the circular arcs occupies 1/4 of the perimeter of the section;

the second steel ball mounting roller path comprises four sections of eccentric circular arcs, and each section of the circular arcs occupies 1/4 of the section perimeter;

the circular arcs of the first steel ball mounting raceway and the second steel ball mounting raceway are the same, and the second steel ball is in point contact with the four circular arcs of the first steel ball mounting raceway and the four circular arcs of the second steel ball mounting raceway.

Further, when M is 2,

the first steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section of the eccentric circular arcs accounts for 1/2 of the perimeter of the section;

the second steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section occupies 1/2 of the section perimeter;

the circular arc of the first steel ball mounting raceway and the circular arc of the second steel ball mounting raceway are arranged in a mirror image mode.

Further, when M is 3,

the first steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section of the eccentric circular arcs accounts for 1/2 of the perimeter of the section;

the second steel ball mounting raceway comprises four sections of eccentric circular arcs, each section occupies 1/4 of the perimeter of the cross section, and the second steel ball and the four sections of circular arcs of the second steel ball mounting raceway are all in point contact;

the third steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section of the eccentric circular arcs accounts for 1/2 of the perimeter of the section;

the circular arc of the first steel ball mounting raceway and the circular arc of the third steel ball mounting raceway are arranged in a mirror image mode.

Furthermore, S shallow grooves are arranged on the inner wall of a planet wheel bearing mounting hole of each stage of the planet gear speed reducing mechanism, and the S shallow grooves correspond to the S first inner ring outer raceways one to one; the first inner ring outer raceway is composed of a first arc and a second arc which are arranged eccentrically, and the first steel balls are respectively in point contact with the first arc and the second arc and are in contact with the shallow grooves, so that a three-point contact type ball bearing structure is formed.

Furthermore, the N-stage planetary gear speed reducing mechanism shares one inner gear shell, and the modulus of the planet gears in each stage of planetary gear speed reducing mechanism is the same.

The invention has the following beneficial effects:

1. the reducer of the invention axially positions the planet wheel of the first-stage planetary gear reducing mechanism by adopting the retainer ring for holes, axially positions the planet wheel bearing by the planet carrier of the current stage, axially positions the planet carrier of the previous stage by the first external tooth of the sun wheel of the next stage, and simultaneously, the planet wheel of the same stage and the planet carrier are directly contacted to realize mutual axial positioning, compared with the structure of the existing reducer, the structure of the invention not only shortens the whole axial size of the planetary gear reducer, but also reduces the characteristics and the quantity of parts, and reduces the manufacturing cost, meanwhile, the planet carrier center of the N-stage planetary gear reducing mechanism is provided with a positioning through hole for installing a motor, each stage of the sun wheel is provided with a central through hole, and the central through hole of the sun wheel of the 1-stage planetary gear reducing mechanism is internally provided with a key groove for connecting with the output end of an external motor, and the design ensures that the motor matched with the reducer can be arranged at the high-speed side (power input side), the speed reducer can be arranged on a low-speed side (power output side), so that the structure adaptability of the whole speed reducer is strong, and the speed reducer is suitable for different use scenes.

2. According to the invention, the end face of the planet carrier at the upper stage of the adjacent two-stage planetary gear speed reducing mechanism and the end face of the planet gear at the current stage form a micro gap, so that a space is reserved for grease while the axial positioning function is borne, an oil film is established between contact surfaces, the lubrication is improved, and the abrasion is reduced; meanwhile, the manufacturing tolerance is increased, and the manufacturing difficulty is reduced.

3. The planet wheel bearing in the Nth-stage planetary gear speed reducing mechanism adopts a three-point contact type ball bearing structure, and compared with the cylindrical needle bearing adopted by the existing planet wheel bearing, the manufacturing precision is higher, the bearing capacity and the rigidity are stronger, and the transmission precision is higher; meanwhile, the three-point contact type ball bearing structure can be preloaded to eliminate bearing play, so that the reverse clearance of the speed reducer is reduced, the number of rows of steel balls is increased in order to shorten the axial size of the planetary gear speed reducing mechanism or in the same axial space, and the bearing capacity is improved.

4. The planet carrier of the N-stage planetary gear speed reducing mechanism of the speed reducer is in rotary connection with the inner gear shell through the single-row contact type ball bearing, the bearing can bear radial load and axial load at the same time, and compared with the structure of the existing speed reducer, the bearing capacity of the speed reducer to axial and bending moment loads is greatly improved; meanwhile, the contact type ball bearing structure adopts the filling structure consisting of the axial hole, the ball filling hole and the anti-falling structure, so that the problem that the splicing gap is inevitably generated by adopting an upper splicing structure and a lower splicing structure is solved, the manufacturing precision is improved, the rigidity of the roller path is effectively ensured, and the abrasion of the ball in the roller path caused by the splicing type roller path gap is reduced.

5. The invention adopts the design that all stages of planetary gear reduction mechanisms share one inner gear shell and all stages of planetary gears have the same modulus, thereby enabling the width size of the planetary gears in all stages of planetary gear reduction mechanisms to be thinner and further reducing the axial size of the speed reducer.

Drawings

Fig. 1 is a schematic structural view of a conventional planetary gear reducer.

Fig. 2 is a schematic structural view of a planetary gear reducer for a robot according to the present invention.

FIG. 3 is a schematic view of a planet wheel bearing without shallow grooves.

Fig. 4 is a schematic view of a planetary wheel bearing with shallow grooves.

FIG. 5 is a schematic diagram of two adjacent rows of first steel balls in the planet wheel bearing in a circumferentially staggered arrangement.

Fig. 6 is a schematic end view of a carrier of the 3 rd stage planetary gear reduction mechanism.

FIG. 7 is a partial schematic view of a contact ball bearing arrangement mounted on a carrier;

FIG. 8 is a schematic view of a single row contact ball bearing configuration;

FIG. 9 is a schematic view of a first form of 2 row contact ball bearing configuration;

FIG. 10 is a schematic view of a second form of 2-row contact ball bearing arrangement;

FIG. 11 is a schematic view of a third form of 2 row contact ball bearing configuration;

FIG. 12 is a schematic view of a 3-row contact ball bearing configuration;

FIG. 13 is a schematic view of the motor as it is disposed on the power input side;

fig. 14 is a schematic diagram when the motor is disposed on the power output side.

The reference numbers are as follows:

100-inner gear shell, 1001-second outer ring inner raceway;

200-planetary gear speed reducing mechanism, 201-sun gear, 2011-first outer gear, 2012-second outer gear, 2013-central through hole, 202-planet gear, 203-planet carrier, 2031-second inner ring outer raceway, 2032-axial hole, 2033-ball filling hole, 2034-motor positioning through hole, 204-planet shaft, 2041-first inner ring outer raceway, 2042-circular arc channel, 206-planet shaft mounting hole, 207-planet gear inner hole and 2071-shallow groove;

300-hole retainer ring;

400-a first steel ball;

500-mounting a raceway by steel balls;

600-a second steel ball;

700-anti-disengagement structure, 701-pin shaft, 702-limit hole and 703-tightening screw.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below, and it is apparent that the described embodiments are a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present invention.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Meanwhile, in the description of the present invention, it should be noted that the terms "upper, lower, inner and outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and operate, and thus, cannot be construed as limiting the present invention. Furthermore, the terms first, second, or third are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The terms "mounted, connected and connected" in the present invention are to be understood broadly, unless otherwise explicitly specified or limited, for example: can be fixedly connected, detachably connected or integrally connected: they may be mechanically, electrically, or directly connected, or indirectly connected through intervening media, or may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The present embodiment provides a planetary gear reducer for a robot, specifically as shown in fig. 2, the reducer includes an inner gear housing 100 and N-stage planetary gear reduction mechanisms 200 sequentially arranged along an axial direction of the inner gear housing 100; n is greater than or equal to 2, and in the embodiment, N is 3, wherein the first-stage planetary gear reduction mechanism is a high-speed-stage input end of the speed reducer, the 2 nd-stage planetary gear reduction mechanism is a medium-speed stage, and the 3 rd-stage planetary gear reduction mechanism is a low-speed-stage output end of the speed reducer; each stage of the planetary gear reduction mechanism 200 includes a sun gear 201, a planetary gear 202, a planetary carrier 203, and a planetary shaft 204.

In order to solve the problems of the existing planetary gear reducer, the planetary gear reducer has the following three-point core design: a: the planetary gear reducer adopts the structural design of an integral axial reduced scale; b: the planet wheel bearing adopts the structural design of a three-point contact type ball bearing; c: the contact type ball bearing structure at the Nth-stage planet carrier is designed; the above three-point core design is described in detail below with reference to the accompanying drawings:

A. structural design of integral axial reduced scale

In the embodiment, as shown in fig. 2, the planet gear 202 of the 1 st stage planetary gear speed reduction mechanism 200 is axially positioned by a retainer ring 300 for a hole that is snap-fitted inside the inner gear case 100;

a first external tooth 2011 and a second external tooth 2012 are arranged on the sun wheel 201 of the 2 nd to 3 rd stages of planetary gear speed reducing mechanisms 200 along the axial direction of the sun wheel, and the tooth height of the first external tooth 2011 is greater than that of the second external tooth 2012; the first external teeth 2011 of each stage of the sun gear 200 are meshed with the planet gear 202 of the current stage, and the second external teeth 2012 are in key connection with the planet carrier 203 of the previous stage; the end surface of the previous-stage planet carrier 203 is in end surface contact with the first external teeth 2011 on the current-stage sun gear 201;

the planet shaft 204 of each stage of planetary gear reduction mechanism is in interference fit with the planet shaft mounting hole 206 on the planet carrier 203, and the planet gear 202 and the planet carrier 203 of the 3 rd stage planetary gear reduction mechanism are in mutual contact to realize the axial positioning of the planet gear in the 3 rd stage planetary gear reduction mechanism;

in addition, in order to further reduce the axial size of the speed reducer, in the present embodiment, the 3-stage planetary gear speed reducing mechanism shares one inner gear case 100, and the module of the planet wheels 202 in each stage of planetary gear speed reducing mechanism is the same, so that the width size of the planet wheels 202 (particularly, the 1 st stage planet wheels and the 2 nd stage planet wheels) in each stage of planetary gear speed reducing mechanism can be reduced.

B. Structural design of three-point contact type ball bearing adopted by planet wheel bearing

As shown in fig. 2 and 3, in the 1 st to 3 rd planetary gear speed reduction mechanisms 200, S first inner ring outer raceways 2041 are axially and side by side formed on the outer surface of the planet shaft 204 located in the planet wheel bearing mounting hole 207, S is not less than 2, and a plurality of first steel balls 400 are circumferentially arranged between each first inner ring outer raceway 2041 and the hole wall of the planet wheel bearing mounting hole 207; first steel balls 400 mounted in every two adjacent first inner ring outer raceways 2041 are arranged in a staggered manner in the circumferential direction, so that a planetary wheel bearing of the N-stage planetary gear reduction mechanism is formed; one side of the planet wheel bearing mounting hole 207, which is close to the planet carrier, is provided with an inwardly protruding circular arc-shaped groove 2042 for axially positioning the first steel ball 400.

In order to more reliably position the first steel ball 400, as shown in fig. 2 and 4, in this embodiment, an S-bar shallow groove 2071 is further formed on an inner wall of the planet wheel bearing mounting hole 207, the S-bar shallow groove 2071 corresponds to the S-bar first inner ring outer raceway 2041 one to one, the first inner ring outer raceway 2041 is formed by two arcs arranged eccentrically and respectively marked as a fifth arc and a sixth arc, and the first steel ball 400 is in point contact with the two arcs and is in contact with the shallow groove 2071, so as to form a more reliable three-point contact type ball bearing structure.

C. Contact type ball bearing structure design at Nth-stage planet carrier

As shown in fig. 2 and 6, the planet carrier 203 of the 3 rd-stage planetary gear speed reducing mechanism is rotationally connected with the inner gear housing 100 through at least one row of contact ball bearing structures (in this embodiment, the contact ball bearing structure is a row), and at the same time, the contact ball bearing structures realize axial positioning of the planet carrier of the 3 rd-stage planetary gear speed reducing mechanism;

the contact type ball bearing structure comprises M second inner ring outer raceways 2031 arranged on the outer surface of a planet carrier 203 of the 3 rd-level planetary gear speed reducing mechanism along the axial direction, and M second outer ring inner raceways 1001 corresponding to the M second inner ring outer raceways 2031 one by one are arranged on the inner wall of the inner gear housing 100 along the axial direction; m is more than or equal to 1;

m steel ball mounting raceways 500 are formed between the M second inner ring outer raceways 2031 and the M second outer ring inner raceways 1001; a plurality of second steel balls 600 are arranged in each steel ball mounting roller path along the circumferential direction;

at least one axial hole 2032 is formed in the carrier 203 of the 3 rd stage planetary gear reduction mechanism, M ball filling holes 2033 are formed in positions corresponding to the positions of the axial hole 2032 and the second inner ring outer raceway 2031, and an anti-disengagement structure 700 for preventing the balls from disengaging is provided in each ball filling hole 2033.

The anti-falling structure can be selected in many forms, and the purpose of the anti-falling structure is that after the processing is completed, the second steel ball 600 cannot fall out of the ball filling hole 2033 during the working process, especially under the condition of large load; preferably, the second steel ball 600 cannot be separated from the ball filling hole 2033 during operation, and the raceway can be opened to remove the second steel ball 600 when maintenance is required.

The ball filling hole 2033 should be perpendicular to the ball mounting raceway 500, that is: the direction perpendicular to the axial hole 2032 is set to be the best, and an oblique direction can be set, but when the oblique direction is set, firstly, the processing cost is increased, and secondly, the risk of reducing the rigidity of the bearing exists.

Based on the above conditions, two specific structures of the anti-disengagement structure are provided for reference, and the embodiment adopts the 1 st:

1. as shown in fig. 7, a pin 701 is provided in the ball filling hole 2033, a stopper hole 702 is provided in the carrier 203 of the 3 rd stage planetary gear reduction mechanism, the stopper hole 702 communicates with the ball filling hole 2033, and the pin 701 is positioned by fitting a fastening screw 703 into the stopper hole 702. The better way of the position limiting hole 702 is that the central axis is parallel to the central axis of the axial hole 2032, so that the stress is relatively balanced when the position limiting and jacking are carried out. The pin 701 is fixed. If the contact ball bearing structure has multiple rows, the position-limiting holes 702 should be arranged in a staggered manner, and the position-limiting holes closer to the central row are deeper, in which case the axial holes 2032 should be equal to the number of raceways.

The method for processing and assembling the contact type ball bearing structure in the embodiment specifically comprises the following steps:

step 1: machining M second outer ring inner raceways 1001 on the inner gear shell 100;

and 2, step: an axial hole 2032, M ball filling holes 2033, and M limit holes 702 that are processed in the carrier 203 of the 3 rd stage planetary gear reduction mechanism; after the axial hole 2032, the M ball filling holes 2033 and the M limiting holes 702 are manufactured, the pin shafts 701 are respectively installed in the M ball filling holes 2032, then the limiting devices are installed in the limiting holes 702 to fix the pin shafts 701, and after the fixing, the pin shafts 701 are processed, so that one ends of the pin shafts 701, far away from the second outer ring inner raceway 1001, are coplanar with the hole wall of the axial hole 2032;

alternatively, M ball filling holes 2032 and M limit holes 702 on the carrier 203 of the 3 rd stage planetary gear reduction mechanism are first made; after the M ball filling holes 2032 and the M limiting holes 702 are manufactured, the pin shafts 701 are all installed in the M ball filling holes 2032, then the limiting devices are installed in the limiting holes 702 to fix the pin shafts 701, and after the fixing, the axial holes 2032 are manufactured, so that one end of each pin shaft 701, which is far away from the second outer ring inner raceway 1001, is coplanar with the hole wall of the axial hole 2032;

and step 3: processing M second inner ring outer raceways 2031 on a planet carrier 203 of the 3 rd-level planetary gear reduction mechanism, and simultaneously processing each pin shaft 701 extending into the second inner ring outer raceway 2031 through a ball filling hole 2032, so that one end of each pin shaft 701 extending into the second inner ring outer raceway 2031 is coplanar with the wall of the second inner ring outer raceway 2031; after the manufacturing is finished, the pin shaft 701 and the limiting device are removed;

and 4, step 4: the second steel ball 600 is loaded, and the step has the following two modes:

mode 1:

step 4.1: filling a second steel ball 600 into a raceway through the ball filling hole 2032 manufactured in the step 3; grease can be coated in the second steel balls 600 and/or the roller paths to reduce the installation difficulty;

step 4.2: rotating the inner gear shell 100 to enable the second steel balls 600 filled in the step 4.1 to stagger the ball filling holes 2032;

step 4.3: a second steel ball 600 is filled into the raceway through the ball filling hole 2032;

step 4.4: the steps 4.2 to 4.3 are circulated until all the second steel balls 600 are filled into the raceway;

step 4.5: the steps 4.1 to 4.4 are circulated to fill other raceways until all the raceways are filled;

the second method comprises the following steps:

step 4.1: respectively filling a second steel ball 600 into each raceway through the ball filling hole 2032 manufactured in the step 3;

step 4.2: rotating the inner gear shell 100 to enable each second steel ball 600 filled in the step 4.1 to stagger the ball filling hole 2032;

step 4.3: filling a second steel ball 600 into each raceway through the ball filling hole 2032;

step 4.4: the steps 4.2 to 4.3 are circulated until all the second steel balls 600 are filled into each raceway;

and 5: and installing a pin shaft 701 in the ball filling hole 2032 for plugging, and installing a limiting device in the limiting hole 702 for fixing the pin shaft 701.

2. Set up isosceles trapezoid elastic sleeve in the ball filling hole, the great bottom surface of this sleeve pipe area is towards the bearing center, and the less top surface of area is towards second inner circle outer raceway, and the great diameter of area is greater than the second steel ball diameter, and the less diameter of area is less than the second steel ball diameter, but the difference need ensure that the deformation that produces when the installation can be crowded into the second steel ball, can not extruded through its intensity when this position department atress of second steel ball during operation simultaneously.

In this embodiment, when the number M of the ball mounting raceways 500 is 1: the steel ball mounting raceway 500 comprises four segments of eccentric circular arcs, each segment occupies 1/4 of the section perimeter, and the second steel ball 600 is in point contact with the four segments of circular arcs of the steel ball mounting raceway 500. Specifically, as shown in fig. 8, each second outer ring inner raceway 1001 is formed by a first arc a1 and a second arc a2 which are eccentrically arranged, and the second steel ball 600 is in point contact with the first arc a1 and the second arc a2 respectively, and the contact points are respectively denoted as S1 and S2; each second inner ring outer raceway 2031 is formed by a third arc A3 and a fourth arc a4 which are arranged eccentrically, and the second steel ball 600 is in point contact with the third arc A3 and the fourth arc a4 respectively, and the contact points are respectively marked as S3 and S4, so that a four-point contact ball bearing structure is formed. In order to further reduce the wear of the steel balls, the contact points of the second steel ball 600 with the first arc and the fourth arc and three points at the center of the second steel ball 600 are collinear (as shown in fig. 8, namely three points S1, S4 and O are collinear); the contact points of the second steel ball 600 with the second arc, the third arc and the center of the second steel ball 600 are collinear (as shown in fig. 8, i.e., the three points S2, S3 and O are collinear).

When the number M of the steel ball mounting raceways 500 is 2, three structural forms exist:

the first form is:

the first steel ball mounting raceway comprises four sections of eccentric circular arcs, and each section of the circular arcs occupies 1/4 of the perimeter of the section; the second steel ball mounting raceway comprises four sections of eccentric circular arcs, and each section of the eccentric circular arcs accounts for 1/4 of the perimeter of the section; the circular arc of the first steel ball mounting raceway is the same as the circular arc of the second steel ball mounting raceway, and the second steel ball 600 is in point contact with the four circular arcs of the first steel ball mounting raceway, and the second steel ball 600 is in point contact with the four circular arcs of the second steel ball mounting raceway, as shown in fig. 8;

the second and third forms are:

the first steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section of the eccentric circular arcs accounts for 1/2 of the perimeter of the section; the second steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section occupies 1/2 of the section perimeter; the circular arcs of the first ball mounting raceway and the circular arcs of the second ball mounting raceway are arranged in mirror image, and the structures presented by the circular arcs are back-to-back mirror images (as shown in figure 9) or face-to-face mirror images (as shown in figure 10).

As shown in fig. 11, when the number M of the steel ball mounting raceways is 3, the first steel ball mounting raceway includes two sections of eccentric circular arcs, each section occupying 1/2 of the section circumference; the second steel ball mounting raceway comprises four sections of eccentric circular arcs, each section occupies 1/4 of the perimeter of the cross section, and the second steel ball and the four sections of circular arcs of the second steel ball mounting raceway are all in point contact; the third steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section of the eccentric circular arcs accounts for 1/2 of the perimeter of the section; the circular arc of the first steel ball mounting raceway and the circular arc of the third steel ball mounting raceway are arranged in a mirror image mode.

In addition to the above three cores, in order to be applicable to different use scenarios, in the present embodiment, through the special design of the sun gear of each stage and the carrier of the nth stage, it is realized that the motor used in cooperation with the speed reducer can be installed on both the high-speed side (power input side) and the low-speed side (power output side), and the specific structure is as shown in fig. 13 and fig. 14:

each stage of sun gear 201 is provided with a central through hole 2013, and a key groove used for being connected with the output end of an external motor is arranged in the central through hole 2013 of the sun gear 201 of the 1 st stage of planetary gear speed reducing mechanism; a motor positioning through hole 2034 is formed in the center of the planet carrier 203 of the 3 rd-stage planetary gear speed reducing mechanism; when the motor sets up in the high-speed side, as shown in fig. 13, outside motor is close to 1 st level planetary gear reduction mechanism one side, and the direct sun gear key-type connection with 1 st level planetary gear reduction mechanism of output of motor, when the motor sets up in the high-speed side, as shown in fig. 14, the motor is close to N th level planetary gear reduction mechanism one side, and the motor passes through behind the motor positioning hole location, the motor output passes behind 2 nd level planetary gear reduction mechanism's the sun gear with 1 st level planetary gear reduction mechanism's sun gear key-type connection.

Claims (10)

1. A planetary gear reducer for a robot comprises an inner gear shell and N-stage planetary gear reducing mechanisms which are sequentially arranged along the axial direction of the inner gear shell; n is more than or equal to 2; each stage of planetary gear speed reducing mechanism comprises a sun gear, a planetary carrier and a planetary shaft;

the method is characterized in that:

a planet wheel of the 1 st-stage planetary gear speed reducing mechanism is axially positioned by a retainer ring through a hole clamped in the inner gear shell;

in the 2 nd to N-stage planetary gear speed reducing mechanisms, the sun gear is provided with a first external tooth and a second external tooth, and the tooth height of the first external tooth is larger than that of the second external tooth; the first external teeth are meshed with the planet wheel of the current stage, and the second external teeth are in key connection with the planet carrier of the previous stage; the end face of the previous-stage planet carrier is in contact with the end face of the first external tooth on the current-stage sun gear, and simultaneously forms a micro gap with the end face of the current-stage planet gear;

the planet shaft of each stage of planetary gear speed reducing mechanism is in interference fit with the planet shaft mounting hole on the planet carrier, and the planet gear of the Nth stage of planetary gear speed reducing mechanism is in mutual contact with the planet carrier to realize the axial positioning of the planet gear in the Nth stage of planetary gear speed reducing mechanism;

in the 1-N-stage planetary gear speed reducing mechanism, S first inner ring outer raceways are axially arranged on the outer surface of a planetary shaft in a planetary wheel bearing mounting hole side by side, S is more than or equal to 2, and a plurality of first steel balls are arranged between each first inner ring outer raceway and the hole wall of the planetary wheel bearing mounting hole along the circumferential direction; first steel balls arranged in every two adjacent first inner ring outer raceways are arranged in a staggered manner in the circumferential direction, so that a planetary wheel bearing of the N-stage planetary gear speed reducing mechanism is formed; one side of the planet wheel bearing mounting hole, which is close to the planet carrier, is provided with an arc-shaped groove which protrudes inwards and is used for axially positioning the first steel ball;

the planet carrier of the Nth-stage planetary gear speed reducing mechanism is in rotary connection with the inner gear shell through at least one row of contact type ball bearing structures, and meanwhile, the contact type ball bearing structures realize the axial positioning of the planet carrier in the Nth-stage planetary gear speed reducing mechanism;

the contact type ball bearing structure comprises M second inner ring outer raceways which are arranged on the outer surface of a planet carrier of the Nth-stage planetary gear speed reducing mechanism along the axial direction, and M second outer ring inner raceways which are in one-to-one correspondence with the M second inner ring outer raceways are arranged on the inner wall of the inner gear shell along the axial direction; m is more than or equal to 1;

m steel ball mounting raceways are formed between the M second inner ring outer raceways and the M second outer ring inner raceways; a plurality of second steel balls are arranged in each steel ball mounting roller path along the circumferential direction;

the planet carrier of the Nth-stage planetary gear speed reducing mechanism is provided with at least one axial hole, M ball filling holes are formed in the axial hole and at the positions corresponding to the outer raceway of the second inner ring, and an anti-disengagement structure for preventing the balls from disengaging is arranged in each ball filling hole;

a key groove used for being connected with the output end of an external motor is arranged in a central through hole of a sun gear of the 1 st-stage planetary gear speed reducing mechanism.

2. The planetary gear reducer for robots as set forth in claim 1, wherein: each stage of sun wheel is provided with a central through hole; a positioning through hole for mounting a motor is formed in the center of a planet carrier of the Nth-stage planetary gear speed reducing mechanism, and a key groove is formed in a central through hole of a sun gear in the 1 st-stage planetary gear speed reducing mechanism.

3. The planetary gear reducer for robots according to claim 2, characterized in that: a planet carrier of the Nth-stage planetary gear speed reducing mechanism is also provided with a limiting hole, and the limiting hole is communicated with the ball filling hole; and a limiting device for preventing the anti-falling structure from moving is arranged in the limiting hole.

4. The planetary gear reducer for robots according to claim 3, characterized in that: the limiting hole is a screw hole parallel to the axial hole, and the limiting device is a fastening screw.

5. A planetary gear reducer for a robot according to any one of claims 1 to 4, wherein: when M is 1: the steel ball mounting raceway comprises four sections of eccentric circular arcs, each section occupies 1/4 of the section perimeter, and the second steel ball is in point contact with the four sections of circular arcs of the steel ball mounting raceway.

6. A planetary gear reducer for a robot according to any one of claims 1 to 4, wherein:

when the M is 2, the compound is,

the first steel ball mounting raceway comprises four sections of eccentric circular arcs, and each section of the circular arcs occupies 1/4 of the perimeter of the section;

the second steel ball mounting raceway comprises four sections of eccentric circular arcs, and each section of the eccentric circular arcs accounts for 1/4 of the perimeter of the section;

the circular arcs of the first steel ball mounting raceway and the second steel ball mounting raceway are the same, and the second steel ball is in point contact with the four circular arcs of the first steel ball mounting raceway and the four circular arcs of the second steel ball mounting raceway.

7. A planetary gear reducer for a robot according to any one of claims 1 to 4, wherein:

when the M is 2, the compound is,

the first steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section occupies 1/2 of the section perimeter;

the second steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section occupies 1/2 of the section perimeter;

the circular arc of the first steel ball mounting raceway and the circular arc of the second steel ball mounting raceway are arranged in a mirror image mode.

8. A planetary gear reducer for a robot according to any one of claims 1 to 4, wherein:

when the M is 3, the compound is,

the first steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section of the eccentric circular arcs accounts for 1/2 of the perimeter of the section;

the second steel ball mounting raceway comprises four sections of eccentric circular arcs, each section occupies 1/4 of the perimeter of the cross section, and the second steel ball and the four sections of circular arcs of the second steel ball mounting raceway are all in point contact;

the third steel ball mounting raceway comprises two sections of eccentric circular arcs, and each section of the eccentric circular arcs accounts for 1/2 of the perimeter of the section;

the circular arc of the first steel ball mounting raceway and the circular arc of the third steel ball mounting raceway are arranged in a mirror image mode.

9. The planetary gear reducer for robots according to claim 1, characterized in that: s shallow grooves are formed in the inner wall of a planet wheel bearing mounting hole of each stage of planet gear speed reducing mechanism and correspond to the S first inner ring outer raceways one by one; the first inner ring outer raceway is composed of a first circular arc and a second circular arc which are arranged in an eccentric manner, and the first steel balls are respectively in point contact with the first circular arc and the second circular arc and are in contact with the shallow grooves, so that a three-point contact type ball bearing structure is formed.

10. The planetary gear reducer for robots according to claim 1, characterized in that: the N-stage planetary gear speed reducing mechanism shares one inner gear shell, and the modulus of the planetary gears in each stage of planetary gear speed reducing mechanism is the same.

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