Patent Publication Number: US-2022231575-A1

Title: Tubular motor assembly using coreless motor structure

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention belongs to the technical field of motor devices, and particularly relates to a tubular motor assembly using a coreless motor structure. 
     BACKGROUND OF THE INVENTION 
     With the rapid development of the mechanical and electrical industry, motors have been widely used in people&#39;s life at present. For example, as driving devices, tubular motors have the advantages of compact structure, large torque, low rotating speed and the like, so the tubular motors are increasingly used in products that use motors to realize lifting motion, such as roller shutters, sun shading systems and projection screens. Since the motor shafts of the tubular motors are too high in rotating speed, for ease of use, speed reducers are generally provided on the tubular motors, so that the rotating speed of the output shafts satisfies the requirements for normal use. Existing DC tubular motors are generally ordinary rare-earth or ferrite motors, that is, they have the structural characteristic that rotor cores and magnetic shoes are attached to the housing. The existing tubular rare-earth or ferrite motors have many deficiencies. For example, firstly, due to the large mass of the rotor cores, the rotors have slow response, high energy consumption and large vibration, resulting in a serious damage to components and limiting the service life of the whole machine. Then, the rotor cores will produce an eddy current in the magnetic field, resulting in motor heating, high energy consumption and low efficiency. Secondly, since the magnetic shoes (permanent magnets) are fixed on the housing, the magnetic shoes (permanent magnets) must have a certain thickness. When the outer diameter of the motors is given, the outer diameter of the motor rotors will be greatly limited, and the output torque of the motors is thus greatly limited. In addition, the speed reducers of the existing tubular motors cannot satisfy the requirements in term of the speed reduction ratio and are not compact enough in structure and poor in stability during the transmission process. These problems have caused great inconvenience to the existing tubular motors when in use. 
     In order to solve the deficiencies in the prior art, long-term exploration has been conducted, and a variety of solutions have been proposed. For example, Chinese Patent Document disclosed a planetary reducer of a tubular motor [200720184522.7], including a sun gear, an inner toothed end cover, an inner toothed sleeve and an inner toothed sleeve seat, wherein the planetary reducer is internally provided with: a primary support main body, on which three support pins are provided, primary planetary gears being provided on the support pins, gears being provided at lower ends of the primary planetary gears; a secondary support main body, on which three support pins being provided on the secondary support main body, secondary planetary gears being provided on the support pins, gears being provided at lower ends of the support pins; and, a tertiary support main body, on which three support pins are provided, tertiary planetary gears being provided on the support pins, output shafts being provided at lower ends of the support pins. Although the above solution solves the problem that the speed reducers of the existing tubular motors cannot satisfy the requirements in terms of the speed reduction ratio to a certain extent, this solution still has many deficiencies of ordinary rare-earth or ferrite motor. Meanwhile, this solution still has other deficiencies such as poor transmission stability. 
     SUMMARY OF THE INVENTION 
     In view of the above problems, an objective of the present invention is to provide a tubular motor assembly using a coreless motor structure, which has rational structure and uses a coreless motor structure. 
     In order to achieve the above objective, the present invention employs the following technical solutions. A tubular motor assembly using a coreless motor structure is provided, including a hollow steel tube body, a motor main body being internally provided in the steel tube body, wherein the motor main body is a coreless motor, and one end of the motor main body is inserted at one end of a battery circuit board housing; a control circuit board and/or a power supply battery which is connected to the motor main body and has a control circuit is provided within the battery circuit board housing through a battery circuit board positioning structure; the other end of the motor main body is connected to one end of a primary gear ring through a motor connecting seat, and a motor shaft of the motor main body is connected to a primary planetary gear assembly provided within the primary gear ring; the other end of the primary gear ring is connected to a secondary/tertiary gear ring having a secondary planetary gear assembly and a tertiary gear ring connected to each other through a brake outer sleeve; the primary planetary gear assembly is connected to the secondary planetary gear assembly through a brake structure located in the brake outer sleeve; the tertiary planetary gear assembly is connected to an output shaft which extends to the outer side of one end of the steel tube body; and, the other end of the steel tube body away from the output shaft is connected to a cover body through a limiting ring. 
     In the tubular motor assembly using a coreless motor structure, the battery circuit board positioning structure includes a circuit board mounting region and a battery mounting region successively formed within the battery circuit board housing; a mounting opening which extends in the axial direction of the battery circuit board housing and is respectively communicated with the circuit board mounting region and the battery mounting region is formed on the outer circumferential side of the battery circuit board housing; the control circuit board is provided within the circuit board mounting region through a first positioning structure; and, the power supply battery is provided within the battery mounting region through a second positioning structure. 
     In the tubular motor assembly using a coreless motor structure, the battery circuit board housing includes a cylindrical motor mounting drum; the motor mounting drum is coaxially connected to a battery circuit board mounting drum; the circuit board mounting region and the battery mounting region are successively formed within the battery circuit board mounting drum; the mounting opening is axially provided on the outer circumferential side of the battery circuit board mounting drum; one end of the motor main body is inserted into the motor mounting drum; the motor mounting drum and the battery circuit board mounting drum are separated from each other through a closure plate; a number of through holes for allowing terminals at one end of the motor main body to be inserted therein are formed on the closure plate; the terminals of the motor main body are connected to the control circuit board, respectively; mounting plates which go beyond the mounting opening and extend in the axial direction of the battery circuit board mounting drum are provided on two sides of the mounting opening, respectively; the mounting plates are parallel to each other; and, one end of each of the mounting plates is connected to the closure plate, while the other end thereof extends to an end of the battery circuit board mounting drum. 
     Preferably, herein, the first positioning structure includes positioning steps provided on bottoms of opposite sides of the mounting plates; two sides of the control circuit board are clamped between the two mounting plates, and the inner side of the control circuit board is resisted against the positioning steps; and, a battery circuit board upper housing which can seal the part of the mounting opening corresponding to the control circuit board and is shaped as an arc-shaped plate is provided on the battery circuit board mounting drum through a detachable assembly. The detachable assembly includes a number of snaps or necks provided on the outer sides of the mounting plates, respectively; a number of necks or snaps are provided on two sides of the battery circuit board upper housing, respectively; the snaps are clamped into the necks; and, the battery circuit board upper housing and the battery circuit board mounting drum are encircled to form a cylindrical structure. The second positioning structure includes a partition plate which is provided between the two mounting plates and partitions the inner cavity of the battery circuit board housing into the circuit board mounting region and the battery mounting region; a battery limiting portion connected to the mounting plates is provided at one end of the battery circuit board mounting drum away from the circuit board mounting region; the power supply battery is rod-shaped and clamped between the partition plate and the battery limiting portion; and, the outer side of the power supply battery goes beyond the mounting opening. The motor mounting drum and the battery circuit board mounting drum are connected to form an integral structure, the outer side of the motor mounting drum is flush with the outer side of the battery circuit board upper housing, and the outer side of the power supply battery does not go beyond the outer side of the motor mounting drum. 
     In the tubular motor assembly using a coreless motor structure, the brake structure includes a brake mandrel which is provided within the brake outer sleeve through a circumferential positioning structure; a cylindrical brake drum is provided at one end of the brake mandrel, and a brake torsion spring is sleeved on the brake drum; a brake driving member and a brake driven member arranged coaxially are internally provided in the brake outer sleeve; the brake driving member is connected to an output end of the primary planetary gear assembly, and the brake driven member is connected to an input end of the secondary planetary gear assembly; the brake driving member is provided with two driving jaws, and one end of the brake driven member close to the brake driving member passes through the brake mandrel and is provided with two driven jaws; the driving jaws and the driven jaws are staggered one by one, and any one of the driving jaws is located on one side of any one of the driven jaws; and, a brake control assembly, which enables the brake torsion spring to expand in the circumferential direction and the brake driven member to rotate synchronously with the brake driving member in the same direction when the brake driving member rotates in the circumferential direction or enables the brake torsion spring to contract in the circumferential direction and the brake driven member to stop in the circumferential direction when the brake driven member rotates in the circumferential direction, is provided between the driving jaws and the driven jaws. 
     In the tubular motor assembly using a coreless motor structure, the brake control structure includes bent legs which are formed at two ends of the brake torsion springs and bent outward in the radial direction; any one of the two driven jaws of the brake driven member is located between the two bent legs, and any one of the two bent legs is located between the driven jaws and the driving jaws; steps which extend outward in the widthwise direction of the driven jaws and are resisted against one side of the driving jaws are provided on two sides of one end of each of the driven jaws close to the brake driven member; and, gas for allowing the bent legs to extend therein are formed between the outer side of ends of the driven jaws away from the steps and the driving jaws. 
     In the tubular motor assembly using a coreless motor structure, the distance between the two bent legs of the brake torsion spring in the center line direction of the brake torsion spring is greater than the width of ends of the driven jaws away from the steps. 
     In the tubular motor assembly using a coreless motor structure, the brake mandrel includes a mandrel ring body coaxially connected to the brake drum; the mandrel ring body and the brake drum are of an integral structure, and the inner circumferential side of the mandrel ring body is communicated with the inner circumferential side of the brake drum to form a mandrel passage; the circumferential positioning structure includes a number of positioning slots formed on the inner circumferential side of one end of the brake outer sleeve; the positioning slots are arranged in the circumferential direction at uniform intervals and extend in the axial direction of the brake outer sleeve; a number of positioning lugs in one-to-one correspondence to the positioning slots are provided on the outer circumferential side of the mandrel ring body; and, the positioning lugs are clamped into the positioning slots, respectively. 
     In the tubular motor assembly using a coreless motor structure, the motor main body includes a motor shell; a carbon brush set connected to a control circuit is provided at one end of the motor shell; a rotor carrier with the motor shaft is rotatably provided on the carbon brush set, and a coreless coil is provided on the motor shaft; a permanent magnet located on the inner circumferential side of the coreless coil is provided within the motor shell; and, the motor shaft passes through the permanent magnet and extends to the outer side of the motor shell. 
     In the tubular motor assembly using a coreless motor structure, the brake driving member includes a driving mandrel which is coaxially and rotatably provided on the inner circumferential side of one end of the brake outer sleeve through a first rotating bearing; a driving member connecting hole is formed at one end of the driving mandrel, while the other end thereof is coaxially connected to a driving ring body; the driving jaws are correspondingly provided on the outer circumferential side of the driving ring body, respectively; and, one end of the driving ring body away from the driving mandrel is coaxially connected to a rotating drum. 
     In the tubular motor assembly using a coreless motor structure, the brake driven member include a driven mandrel which is coaxially and rotatably provided on the inner circumferential side of one end of the brake outer sleeve away from the driving mandrel through a second rotating bearing; a driven member connecting hole is formed at one end of the driven mandrel, while the other end thereof passes through the mandrel passage and is coaxially connected to a driven drum; the driven jaws are correspondingly provided on the outer circumferential side of one end of the driven drum, respectively; a rotating hole for allowing the rotating drum to be inserted therein is provided at one end of the driven drum, while a limiting ring body is provided at the other end thereof; and, an annular limiting step resisted against the limiting ring body is provided on the inner circumferential side of the brake drum. 
     Herein, the primary planetary gear assembly includes a primary planetary carrier having a primary planetary output shaft provided at its one end and connected to the driving member connecting hole; three primary planetary roller needles are provided on the primary planetary carrier in the circumferential direction at uniform intervals; primary planetary gears are provided on the primary planetary roller needles, and the primary planetary gears are distributed in the circumferential direction at uniform intervals and all connected to the motor shaft of the motor main body; a number of primary gear teeth meshed with the primary planetary gears are provided on the inner circumferential side of the primary gear ring; and, the primary gear teeth and the primary planetary gears are of helical tooth structures. The secondary planetary gear assembly includes a secondary planetary carrier having a secondary planetary output shaft provided at its one end; three secondary planetary roller needles are provided at the other end of the secondary planetary carrier; secondary planetary gears are provided on the secondary planetary roller needles; the secondary planetary gears are distributed in the circumferential direction at uniform intervals and all meshed with a secondary center gear connected to the driven member connecting hole; and, a number of secondary/tertiary gear teeth meshed with the secondary planetary gears are provided on the inner circumferential side of the secondary/tertiary gear ring. The tertiary planetary gear assembly includes a tertiary planetary carrier having an output shaft provided at its one end; three tertiary planetary roller needles are provided at the other end of the tertiary planetary carrier in the circumferential direction at uniform intervals; tertiary planetary gears are provided on the tertiary planetary roller needles; the tertiary planetary gears are distributed on the tertiary planetary gears in the circumferential direction at uniform intervals and all meshed with a small gear on the secondary planetary output shaft; and, secondary/tertiary gear teeth on the inner circumferential side of the secondary/tertiary gear ring are meshed with the tertiary planetary gears, respectively. 
     Preferably, the brake outer sleeve is provided between the primary gear ring and the secondary/tertiary gear ring through a circumferential fixation structure; the circumferential fixation structure includes a first concave-convex positioning assembly provided on the inner circumferential side of one end of the brake outer sleeve; a first concave-convex mating assembly corresponding to the first concave-convex positioning assembly is provided on the inner circumferential side of the primary gear ring; the first concave-convex positioning assembly and the first concave-convex matting assembly are mutually clamped and positioned in the circumferential direction; a second concave-convex assembly is provided on the inner circumferential side of the other end of the brake outer sleeve; a second concave-convex mating assembly corresponding to the second concave-convex positioning assembly is provided on the inner circumferential side of one end of the secondary/tertiary gear ring; and, the second concave-convex positioning assembly and the second concave-convex mating assembly are mutually clamped and positioned in the circumferential direction. 
     Compared with the prior art, the present invention has the following advantages. 
     1. Since the rotor core structure is omitted, the coreless motor does not experience a cogging effect and will not produce an eddy current, thereby reducing heat generation, reducing energy consumption and improving efficiency. Moreover, since there is no rotor core, the mass of the entire rotor is greatly reduced, so that the response speed of a rotor when starting and stopping is greatly improved and vibration is greatly attenuated, thus prolonging the service life of the entire machine. 
     2. The permanent magnet is arranged inside a rotor coil, so the radius of the rotor is increased when the outer diameter of the motor remains unchanged, and the output torque of the motor is increased. 
     3. The transmission between the primary planetary gear assembly and the secondary/tertiary planetary gear assembly is realized by the driving jaws and the driven jaws, and the brake driving member and the brake driven member each have two corners and are resisted against each other, so that the transmission stability is improved, the speed reduction ratio is large, the layout of components is rational, and the structure is compact. 
     4. By making the brake torsion spring be in interference fit with the brake mandrel, the braking process is realized by the deformation of the torsion spring, thereby achieving good braking effect of the brake and high braking sensitivity. 
     5. By supplying power by a battery, the charging interval period is longer, and the vibration and noise of the entire machine are greatly improved, the motor has higher mounting stability, and the components of the motor, the circuit board and the battery are firmly fixed and high in reliability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic structure diagram according to the present invention; 
         FIG. 2  is an exploded view according to the present invention; 
         FIG. 3  is a schematic structure diagram when a motor main body is connected to a battery circuit board housing according to the present invention; 
         FIG. 4  is an exploded view when the motor main body is connected to the battery circuit board housing according to the present invention; 
         FIG. 5  is a schematic structure diagram of the battery circuit board housing according to the present invention; 
         FIG. 6  is a schematic structure diagram when the motor main body is connected to a transmission structure according to the present invention; 
         FIG. 7  is a sectional view when the motor main body is connected to the transmission structure according to the present invention; 
         FIG. 8  is an exploded view when the motor main body is not mounted to the transmission structure according to the present invention; 
         FIG. 9  is an exploded view from another perspective when the motor main body is not mounted to the transmission structure according to the present invention; 
         FIG. 10  is an exploded view when planetary gear assemblies are connected according to the present invention; 
         FIG. 11  is an exploded view from another perspective when planetary gear assemblies connected are connected according to the present invention; 
         FIG. 12  is a partially exploded view of the transmission structure according to the present invention; 
         FIG. 13  is a partially exploded view from another perspective according to the present invention; and 
         FIG. 14  is a schematic structure diagram of a braking process according to the present invention; 
     
    
    
     in which:  1 : primary gear ring;  2 : primary planetary gear assembly;  21 : primary planetary carrier;  211 : primary planetary output shaft;  22 : primary planetary roller needle;  23 : primary planetary gear;  24 : primary gear tooth;  3 : secondary/tertiary gear ring;  4 : secondary planetary gear assembly;  41 : secondary planetary carrier;  411 : secondary planetary output shaft;  42 : secondary planetary roller needle;  43 : secondary planetary gear;  44 : secondary center gear;  45 : secondary/tertiary gear tooth;  5 : tertiary planetary gear assembly;  51 : tertiary planetary carrier;  52 : tertiary planetary roller needle;  53 : tertiary planetary gear;  6 : output shaft;  7 : circumferential fixation structure;  71 : first concave-convex positioning assembly;  72 : first concave-convex mating assembly;  73 : second concave-convex positioning assembly;  74 : second concave-convex mating assembly;  8 : brake outer sleeve;  81 : brake driving member;  811 : driving jaw;  812 : driving mandrel;  8121 : driving member connecting hole;  813 : driving ring body;  814 : rotating drum;  815 : first rotating bearing;  82 : brake driven member;  821 : driven jaw;  821   a : step;  821   b : gap;  822 : driven mandrel;  8221 : driven member connecting hole;  823 : driven drum;  824 : rotating hole;  825 : limiting ring body;  826 : annular limiting step;  827 : second rotating bearing;  83 : brake mandrel;  831 : brake drum;  832 : mandrel ring body;  833 : mandrel passage;  84 : brake torsion spring;  841 : bent leg;  85 : positioning slot;  86 : positioning lug;  9 : motor main body;  91 : motor connecting seat;  92 : motor shaft;  93 : motor shell;  931 : carbon brush set;  932 : rotor carrier;  933 : coreless coil;  934 : permanent magnet;  94 : steel tube body;  95 : battery circuit board housing;  951 : circuit board mounting region;  952 : battery mounting region;  953 : mounting opening;  954 : motor mounting drum;  955 : battery circuit board mounting drum;  956 : closure plate;  957 : through hole;  958 : mounting plate;  96 : control circuit board;  961 : positioning step;  962 : battery circuit board upper housing;  963 : snap;  964 : neck;  97 : power supply battery;  971 : partition plate;  972 : battery limiting portion;  98 : limiting ring; and,  99 : cover body. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be further described below in detail by specific implementations with reference to the accompanying drawings. 
     As shown in  FIGS. 1-5 and 7 , the tubular motor assembly using a coreless motor structure includes a hollow steel tube body  94 . A motor main body  9  is internally provided in the steel tube body  94 . The motor main body  9  is a coreless motor. Herein, the motor main body  9  includes a motor shell  93 . A carbon brush set  931  connected to a control circuit is provided at one end of the motor shell  93 . A rotor carrier  932  with the motor shaft  92  is rotatably provided on the carbon brush set  931 , and a coreless coil  933  is provided on the motor shaft  92 . A permanent magnet  934  located on the inner circumferential side of the coreless coil  933  is provided within the motor shell  93 . The motor shaft  92  passes through the permanent magnet  934  and extends to the outer side of the motor shell  93 . Preferably, herein, one end of the motor main body  9  is inserted at one end of a battery circuit board housing  95 . A control circuit board  96  and/or a power supply battery  97  which is connected to the motor main body  9  and has a control circuit is provided within the battery circuit board housing  95  through a battery circuit board positioning structure. Preferably, herein, the power supply battery  97  may be a rechargeable battery. By supplying power by the battery, the charging interval period is longer, and the vibration and noise of the entire machine are greatly improved. 
     Since the rotor core structure is omitted in the motor main body  9 , the coreless motor does not experience a cogging effect and will not produce an eddy current, thereby reducing heat generation, reducing energy consumption and improving efficiency. Moreover, since there is no rotor core, the mass of the entire rotor is greatly reduced, so that the response speed of a rotor when starting and stopping is greatly improved and vibration is greatly attenuated, thus prolonging the service life of the entire machine. Meanwhile, the permanent magnet  934  is arranged inside a rotor coil, so the radius of the rotor is increased when the outer diameter of the motor remains unchanged, and the output torque of the motor is increased. 
     Further, in this embodiment, the battery circuit board positioning structure includes a circuit board mounting region  951  and a battery mounting region  952  successively formed within the battery circuit board housing  95 . A mounting opening  953  which extends in the axial direction of the battery circuit board housing  95  and is respectively communicated with the circuit board mounting region  951  and the battery mounting region  952  is formed on the outer circumferential side of the battery circuit board housing  95 . The control circuit board  96  is provided within the circuit board mounting region  951  through a first positioning structure, and the power supply battery  97  is provided within the battery mounting region  952  through a second positioning structure. 
     Preferably, herein, the battery circuit board housing  95  includes a cylindrical motor mounting drum  954 . The motor mounting drum  954  is coaxially connected to a battery circuit board mounting drum  955 . The circuit board mounting region  951  and the battery mounting region  952  are successively formed within the battery circuit board mounting drum  955 . The mounting opening  953  is axially provided on the outer circumferential side of the battery circuit board mounting drum  955 , and one end of the motor main body  9  is inserted into the motor mounting drum  954 . The motor mounting drum  954  and the battery circuit board mounting drum  955  are separated from each other through a closure plate  956 , a number of through holes  957  for allowing terminals at one end of the motor main body  9  to be inserted therein are formed on the closure plate  956 , and the terminals of the motor main body  9  are connected to the control circuit board  96 , respectively. Mounting plates  958  which go beyond the mounting opening  953  and extend in the axial direction of the battery circuit board mounting drum  955  are provided on two sides of the mounting opening  953 , respectively. The mounting plates  958  are parallel to each other; and, one end of each of the mounting plates  958  is connected to the closure plate  956 , while the other end thereof extends to an end of the battery circuit board mounting drum  955 . 
     Preferably, herein, the first positioning structure includes positioning steps  961  provided on bottoms of opposite sides of the mounting plates  958 . Two sides of the control circuit board  96  are clamped between the two mounting plates  958 , and the inner side of the control circuit board  96  is resisted against the positioning steps  961 . A battery circuit board upper housing  962  which can seal the part of the mounting opening  953  corresponding to the control circuit board  96  and is shaped as an arc-shaped plate is provided on the battery circuit board mounting drum  955  through a detachable assembly. Herein, the detachable assembly includes a number of snaps  963  or necks  964  provided on the outer sides of the mounting plates  958 , respectively; a number of necks  964  or snaps  963  are provided on two sides of the battery circuit board upper housing  962 , respectively; the snaps  963  are clamped into the necks  964 ; and, the battery circuit board upper housing  962  and the battery circuit board mounting drum  955  are encircled to form a cylindrical structure. In addition, herein, the second positioning structure includes a partition plate  971  which is provided between the two mounting plates  958  and partitions the inner cavity of the battery circuit board housing  95  into the circuit board mounting region  951  and the battery mounting region  952 ; a battery limiting portion  972  connected to the mounting plates  958  is provided at one end of the battery circuit board mounting drum  955  away from the circuit board mounting region  951 ; the power supply battery  97  is rod-shaped and clamped between the partition plate  971  and the battery limiting portion  972 ; and, the outer side of the power supply battery  97  goes beyond the mounting opening  953 . The motor mounting drum  954  and the battery circuit board mounting drum  955  are connected to form an integral structure, the outer side of the motor mounting drum  954  is flush with the outer side of the battery circuit board upper housing  962 , and the outer side of the power supply battery  97  does not go beyond the outer side of the motor mounting drum  954 . 
     Furthermore, as shown in  FIGS. 1-2 and 6-13 , in this embodiment, the transmission structure of the motor main body mainly includes the following. Herein, one end of the motor main body  9  is connected to one end of a primary gear ring  1  through a motor connecting seat  91 , and a motor shaft  92  of the motor main body  9  is connected to a primary planetary gear assembly  2  provided within the primary gear ring  1 . The other end of the primary gear ring  1  is connected to a secondary/tertiary gear ring  3  having a secondary planetary gear assembly  4  and a tertiary gear ring  5  connected to each other through a brake outer sleeve  8 . The primary planetary gear assembly is connected to the secondary planetary gear assembly  4  through a brake structure located in the brake outer sleeve  8 , and the tertiary planetary gear assembly  5  is connected to an output shaft  6  which extends to the outer side of one end of the steel tube body  94 . The other end of the steel tube body  94  away from the output shaft  6  is connected to a cover body  99  through a limiting ring  98 . Herein, a fixation hole connected to an external shaft is formed on the cover body  99 . It is also possible to provide a charging interface, a data interface or the like connected to the control circuit board  96  or the power supply battery  97 . 
     Preferably, herein, the brake structure includes a brake mandrel  83  which is provided within the brake outer sleeve  8  through a circumferential positioning structure. A cylindrical brake drum  831  is provided at one end of the brake mandrel  83 , and a brake torsion spring  84  is sleeved on the brake drum  831 . A brake driving member  81  and a brake driven member  82  arranged coaxially are internally provided in the brake outer sleeve  8 . The brake driving member  81  is connected to an output end of the primary planetary gear assembly  2 , and the brake driven member  82  is connected to an input end of the secondary planetary gear assembly  4 . The brake driving member  81  is provided with two driving jaws  811 , and one end of the brake driven member  82  close to the brake driving member  81  passes through the brake mandrel  83  and is provided with two driven jaws  821 . The driving jaws  811  and the driven jaws  821  are staggered one by one, and any one of the driving jaws  811  is located on one side of any one of the driven jaws  821 . A brake control assembly, which enables the brake torsion spring  84  to expand in the circumferential direction and the brake driven member  82  to rotate synchronously with the brake driving member  81  in the same direction when the brake driving member  81  rotates in the circumferential direction or enables the brake torsion spring  84  to contract in the circumferential direction and the brake driven member  82  to stop in the circumferential direction when the brake driven member  82  rotates in the circumferential direction, is provided between the driving jaws  811  and the driven jaws  821 . 
     Specifically, herein, the brake control structure includes bent legs  841  which are formed at two ends of the brake torsion spring  84  and bent outward in the radial direction. Any one of the two driven jaws  821  of the brake driven member  82  is located between the two bent legs  841 , and any one of the two bent legs  841  is located between the driven jaws  821  and the driving jaws  811 . Steps  821   a  which extend outward in the widthwise direction of the driven jaws  821  and are resisted against one side of the driving jaws  811  are provided on two sides of one end of each of the driven jaws  821  close to the brake driven member  82 . Gaps  821   b  for allowing the bent legs  841  to extend therein are formed between the outer side of ends of the driven jaws  821   a  away from the steps  821   a  and the driving jaws  811 . Herein, the distance between the two bent legs  841  of the brake torsion spring  84  in the center line direction of the brake torsion spring  84  is greater than the width of ends of the driven jaws  821  away from the steps  821   a.    
     Preferably, herein, the brake mandrel  83  includes a mandrel ring body  832  coaxially connected to the brake drum  831 . The mandrel ring body  832  and the brake drum  831  are of an integral structure, and the inner circumferential side of the mandrel ring body  832  is communicated with the inner circumferential side of the brake drum  831  to form a mandrel passage  833 . The circumferential positioning structure includes a number of positioning slots  85  formed on the inner circumferential side of one end of the brake outer sleeve  8 . The positioning slots  85  are arranged in the circumferential direction at uniform intervals and extend in the axial direction of the brake outer sleeve  8 . A number of positioning lugs  86  in one-to-one correspondence to the positioning slots  85  are provided on the outer circumferential side of the mandrel ring body  832 . The positioning lugs  86  are clamped into the positioning slots  85 , respectively. 
     The primary planetary gear assembly  2  is transmitted to the secondary planetary gear assembly  4  through the driving jaws  811  and the driven jaws  821  and then connected to the output shaft  6  through the tertiary planetary gear assembly  5 , so that the transmission stability is improved. Meanwhile, a brake mandrel  83  can be provided within the brake outer sleeve  8 , a brake torsion spring  84  is sleeved on the brake mandrel  83 , and the brake torsion spring  84  acts on the driving jaws  811  and the driven jaws  821 , respectively, so that the purpose of providing a brake between the primary planetary gear assembly and the secondary and tertiary planetary gear assemblies is achieved. 
     Specifically, as shown in  FIG. 14 , no manner when the brake driving member  81  rotates forward or backward in the circumferential direction, the driving jaws  811  are driven to rotate together. The driving jaws  811  first come into contact with one bent leg  841  of the brake torsion spring  84 . When the driving jaws  811  push the bent legs  841 , the brake torsion spring  84  expands in the circumferential direction, so that the inner diameter of the brake torsion spring  84  becomes larger, and the brake torsion spring  84  is separated from the brake mandrel  83 . When the driving jaws  811  continuously rotates to drive the bent legs  841  to move in the gaps  821   b , the inner diameter of the brake torsion spring  84  further becomes larger until one side of the driving jaws  811  is resisted against the steps  821   a  of the driven jaws  821 , so that the driving jaws  811  drive the driven jaws  821  to rotate synchronously when the brake torsion spring  841  is in an expanded state, and the power is transferred to a next stage. No matter when the brake driven member  82  rotates forward or backward in the circumferential direction, the driven jaws  821  are driven to rotate together. Before the steps  821   a  of the driven jaws  821  do not come into with the driving jaws  811 , the driven jaws  821  first make the inner diameter of the brake torsion spring  84  smaller, so that the brake torsion spring  84  is tightly clung to the brake mandrel  83 , and a large friction is generated between the brake torsion spring  84  and the brake mandrel  83 . Thus, the whole braking process is realized, and the power will not be transferred to the brake driving member  81 . 
     For the brake part in this embodiment, the brake mandrel  83  and the brake outer sleeve  8  are fixed. The brake torsion spring  84  is in interference fit with the brake mandrel  83 , and the brake driving member  81  and the brake driven member  82  each have two corners. During rotation, the torque of the motor shaft  92  is transferred to the brake driving member  81  through the primary planetary gear assembly  2 . Regardless of clockwise rotation or counterclockwise rotation, the brake driving member  81  will make the inner diameter of the brake torsion spring  84  larger, so that the brake torsion spring  84  is separated from the brake mandrel  83 , and the torque is transferred to the driven member  82 , then transferred to the secondary planetary gear assembly  4  and the tertiary planetary gear assembly  5  and finally transferred out by the output shaft  6 . When the torque is transferred from the output shaft  6  to the secondary planetary gear assembly  4  and the tertiary planetary gear assembly  5  and then to the brake driven member  82 , regardless of clockwise rotation or counterclockwise rotation, the brake driven member  82  will make the inner diameter of the brake torsion spring  84  smaller, so that the brake torsion spring  84  is tightly clung to the brake mandrel  83 , and a large friction is generated between the brake torsion spring  84  and the brake mandrel  83 . Moreover, since the brake mandrel  83  is fixed, the torque cannot be transferred to the primary planetary gear assembly  2 , thereby realizing the braking effect. 
     Herein, the brake driving member  81  includes a driving mandrel  812  which is coaxially and rotatably provided on the inner circumferential side of one end of the brake outer sleeve  8  through a first rotating bearing  815 . A driving member connecting hole  8121  is formed at one end of the driving mandrel  812 , while the other end thereof is coaxially connected to a driving ring body  813 . The driving jaws  811  are correspondingly provided on the outer circumferential side of the driving ring body  813 , respectively. One end of the driving ring body  813  away from the driving mandrel  812  is coaxially connected to a rotating drum  814 . 
     Further, the brake driven member  82  includes a driven mandrel  822  which is coaxially and rotatably provided on the inner circumferential side of one end of the brake outer sleeve  8  away from the driving mandrel  812  through a second rotating bearing  827 . A driven member connecting hole  8221  is formed at one end of the driven mandrel  822 , while the other end thereof passes through the mandrel passage  833  and is coaxially connected to a driven drum  823 . The driven jaws  821  are correspondingly provided on the outer circumferential side of one end of the driven drum  823 , respectively. A rotating hole  824  for allowing the rotating drum  814  to be inserted therein is formed at one end of the driven drum  823 , while a limiting ring body  825  is provided at the other end thereof. An annular limiting step  826  resisted against the limiting ring body  825  is provided on the inner circumferential side of the brake drum  831 . 
     The primary planetary gear assembly  2  includes a primary planetary carrier  21  having a primary planetary output shaft  211  provided at its one end and connected to the driving member connecting hole  8121 . Three primary planetary roller needles  22  are provided on the primary planetary carrier  21  in the circumferential direction at uniform intervals. Primary planetary gears  23  are provided on the primary planetary roller needles  22 , and the primary planetary gears  23  are distributed in the circumferential direction at uniform intervals and all connected to the motor shaft  92  of the motor main body  9 . A number of primary gear teeth  24  meshed with the primary planetary gears  23  are provided on the inner circumferential side of the primary gear ring  1 . The primary gear teeth  24  and the primary planetary gears  23  are of helical tooth structures. 
     Similarly, herein, the secondary planetary gear assembly  4  includes a secondary planetary carrier  41  having a secondary planetary output shaft  411  provided at its one end. Three secondary planetary roller needles  42  are provided at the other end of the secondary planetary carrier  41 , and secondary planetary gears  43  are provided on the secondary planetary roller needles  42 . The secondary planetary gears  43  are distributed in the circumferential direction at uniform intervals and all meshed with a secondary center gear  44  connected to the driven member connecting hole  8221 . A number of secondary/tertiary gear teeth  45  meshed with the secondary planetary gears  43  are provided on the inner circumferential side of the secondary/tertiary gear ring  3 . 
     Herein, the tertiary planetary gear assembly  5  includes a tertiary planetary carrier  51  having an output shaft  6  provided at its one end. Three tertiary planetary roller needles  52  are provided at the other end of the tertiary planetary carrier  51  in the circumferential direction at uniform intervals, and tertiary planetary gears  53  are provided on the tertiary planetary roller needles  52 . The tertiary planetary gears  53  are distributed in the circumferential direction at uniform intervals and all meshed with a small gear on the secondary planetary output shaft  411 . The secondary/tertiary gear teeth  45  on the inner circumferential side of the secondary/tertiary gear ring  3  are meshed with the tertiary planetary gears  53 , respectively. 
     In order to position the primary gear ring  1  and the secondary/tertiary gear ring  3  at two ends of the brake outer sleeve  8 , herein, the brake outer sleeve  8  is provided between the primary gear ring  1  and the secondary/tertiary gear ring  3  through a circumferential fixation structure  7 . Preferably, the circumferential fixation structure  7  includes a first concave-convex positioning assembly  71  provided on the outer circumferential side of one end of the brake outer sleeve  8 . A first concave-convex mating assembly  72  corresponding to the first concave-convex positioning assembly  71  is provided on the inner circumferential side of one end of the primary gear ring  1 . The first concave-convex positioning assembly  71  and the first concave-convex mating assembly  72  are mutually clamped and positioned in the circumferential direction. A second concave-convex positioning assembly  73  is provided on the outer circumferential side of the other end of the brake outer sleeve  8 . A second concave-convex mating assembly  74  corresponding to the second concave-convex positioning assembly  73  is provided on the inner circumferential side of the secondary/tertiary gear ring  3 . The second concave-convex positioning assembly  73  and the second concave-convex mating assembly  74  are mutually clamped and positioned in the circumferential direction. Preferably, herein, all the first concave-convex positioning assembly  71 , the first concave-convex mating assembly  72 , the second concave-convex positioning assembly  73  and the second concave-convex mating assembly  74  can be of positioning teeth structures, so that circumferential positioning is realized by inserting teeth into each other. 
     The specific embodiments described herein are merely for illustrating the spirit of the present invention. Those skilled in the art can make various modifications or supplements to the specific embodiments described herein or replace the specific embodiments described herein in a similar way, without departing from the spirit of the present invention or the scope defined by the appended claims. 
     Although the terms such as the primary gear ring  1 , the primary planetary gear assembly  2 , the primary planetary carrier  21 , the primary planetary output shaft  211 , the primary planetary roller needle  22 , the primary planetary gear  23 , the primary gear tooth  24 , the secondary/tertiary gear ring  3 , the secondary planetary gear assembly  4 , the secondary planetary carrier  41 , the secondary planetary output shaft  411 , the secondary planetary roller needle  42 , the secondary planetary gear  43 , the secondary center gear  44 , the secondary/tertiary gear tooth  45 , the tertiary planetary gear assembly  5 , the tertiary planetary carrier  51 , the tertiary planetary roller needle  52 , the tertiary planetary gear  53 , the output shaft  6 , the circumferential fixation structure  7 , the first concave-convex positioning assembly  71 , the first concave-convex mating assembly  72 , the second concave-convex positioning assembly  73 , the second concave-convex mating assembly  74 , the brake outer sleeve  8 , the brake driving member  81 , the driving jaw  811 , the driving mandrel  812 , the driving member connecting hole  8121 , the driving ring body  813 , the rotating drum  814 , the first rotating bearing  815 , the brake driven member  82 , the driven jaw  821 , the step  812   a , the gap  812   b , the driven mandrel  822 , the driven member connecting hole  8221 , the driven drum  823 , the rotating hole  824 , the limiting ring body  825 , the annular limiting step  826 , the second rotating bearing  827 , the brake mandrel  83 , the brake drum  831 , the mandrel ring body  832 , the mandrel passage  833 , the brake torsion spring  84 , the bent leg  841 , the positioning slot  85 , the positioning lug  86 , the motor main body  9 , the motor connecting seat  91 , the motor shaft  92 , the motor shell  93 , the carbon brush set  931 , the rotor carrier  932 , the coreless coil  933 , the permanent magnet  934 , the steel tube body  94 , the battery circuit board housing  95 , the circuit board mounting region  951 , the battery mounting region  952 , the mounting opening  953 , the motor mounting drum  954 , the battery circuit board mounting drum  955 , the closure plate  956 , the through hole  957 , the mounting plate  958 , the control circuit board  96 , the positioning step  961 , the battery circuit board upper housing  962 , the snap  963 , the neck  964 , the power supply battery  97 , the partition plate  971 , the battery limiting portion  972 , the limiting ring  98  and the cover body  99  are frequently used herein, the possibility of using other terms is not excluded. These terms are merely used to describe and explain the essence of the present invention more conveniently, and the interpretation of the terms into any additional limitations shall be deviated from the spirit of the present invention.