Actuator and robot including the same

Abstract

The present invention relates to the technical field of robots, and discloses an actuator and a robot including the same. The actuator includes: a housing, a motor, and a speed reducer; the motor is an inner rotor motor, and includes: a stator, a rotor having an annular rotor cavity, and a rotor shaft fixedly connected to or integrated with the rotor; one end of the housing extends inward to form a mounting bracket, the mounting bracket encloses a speed reducer installation cavity, a stator installation cavity is formed between the mounting bracket and the side wall of the housing, and the stator is disposed in the stator installation cavity; the speed reducer is connected to the rotor shaft and is disposed in the speed reducer installation cavity, and at least part of the speed reducer installation cavity is located in the annular rotor cavity. Embodiments of the present invention can provide an actuator with a smaller volume, better heat dissipation and better performance to meet the requirements of high-performance robots, especially small and micro high-performance robots.

Description

Technical Field

[0001] The present invention relates to the technical field of robots, and particularly to an actuator and a robot including the same. Background Art

[0002] In recent years, the field of robots has developed rapidly. The development of robots has put forward higher requirements for actuators. However, currently available actuators on the market, especially small servo motors, generally use high-speed motors with high reduction ratios to achieve a certain output torque. This damages the dynamic performance of the actuator. There has also emerged a batch of QDD actuators (Quasi-direct drive: near direct drive actuators) on the market; QDD actuators mainly use outer rotor motors with low reduction ratios. Although these QDD actuators can achieve certain dynamic performance, they are not compact enough in terms of space and mass and have poor heat dissipation. Restricted by the structure of QDD actuators and the size of motors in the prior art, their size scalability is poor, especially unable to meet the requirements of actuators with a size of 50 mm or less in diameter for small servo motors, and thus unable to meet the needs of high-performance robots, especially small and micro high-performance robots. Summary of the Invention

[0003] In view of this, an object of the present invention is to provide an actuator and a robot including the same, aiming to provide an actuator with a smaller volume, better heat dissipation and better performance to meet the needs of high-performance robots, especially small and micro high-performance robots.

[0004] To solve the above technical problems, an embodiment of the present invention provides an actuator, including: a housing, a motor, and a reducer;

[0005] The motor is an inner rotor motor, including: a stator, a rotor having an annular rotor cavity, and a rotor shaft fixedly connected to or integrally formed with the rotor;

[0006] One end of the housing extends inward to form a mounting bracket. The mounting bracket encloses a reducer mounting cavity, and a stator mounting cavity is formed between the mounting bracket and the side wall of the housing. The stator is disposed in the stator mounting cavity; the reducer is connected to the rotor shaft and disposed in the reducer mounting cavity, and at least part of the reducer mounting cavity is located in the annular rotor cavity.

[0007] An embodiment of the present invention also provides a robot, including: the actuator as described above.

[0008] The actuator and robot of the embodiments of the present invention adopt an inner rotor motor, the rotor has an annular rotor cavity, a mounting frame is provided in the outer shell, the mounting frame forms a reducer mounting cavity, the reducer is connected to the rotor and is arranged in the reducer mounting cavity, and at least part of the reducer mounting cavity is located in the annular rotor cavity, so that the reducer and the rotor can reuse at least part of the axial space, thereby reducing the overall volume of the actuator, which is conducive to meeting the application requirements of high-performance robots.

[0009] As an embodiment, the ratio of the motor constant of the motor to the weight of the motor is greater than or equal to 1.5 Nm / kg√(w);

[0010] Optionally, the inner diameter of the stator is greater than or equal to 75% of the outer diameter of the stator;

[0011] Optionally, the diameter of the annular rotor cavity is greater than or equal to 60% of the outer diameter of the stator.

[0012] As an embodiment, the reducer is a single-stage planetary reducer;

[0013] Optionally, the reduction ratio of the reducer is greater than or equal to 3 and less than or equal to 10;

[0014] Optionally, the reduction mechanism of the single-stage planetary reducer is partially or completely located in the annular rotor cavity;

[0015] Optionally, the input mechanism of the single-stage planetary reducer is a sun gear, which is fixed to the rotor shaft; the reduction mechanism of the single-stage planetary reducer includes: an inner ring gear fixed to the mounting frame and planetary gears meshing with the sun gear and the inner ring gear, and the planetary gears are arranged on a support step formed by extending the mounting frame.

[0016] As an embodiment, the output mechanism of the reducer is a planet carrier;

[0017] Optionally, the actuator further includes an output flange, and the planet carrier and the output flange are integrated into a flange planet carrier.

[0018] As an embodiment, the actuator further includes: a first bearing, a second bearing and a third bearing;

[0019] The rotor is fixed to the mounting frame by means of the first bearing;

[0020] The output mechanism of the reducer is fixed to the rotor through the second bearing;

[0021] The output mechanism of the reducer is fixed to the mounting frame by means of the third bearing;

[0022] The actuator further includes a first limiting structure for defining the axial position of the first bearing, a second limiting structure for defining the axial position of the second bearing, and a third limiting structure for defining the axial position of the third bearing;

[0023] Optionally, the first limiting structure includes: a first limiting portion located on the rotor and a second limiting portion formed by extending from the mounting bracket, and the first limiting portion and the second limiting portion jointly restrict the axial position of the first bearing;

[0024] The second limiting structure includes: a third limiting portion provided on the output mechanism of the speed reducer and a fourth limiting portion provided at the rotor shaft, and the third limiting portion and the fourth limiting portion jointly restrict the axial position of the second bearing;

[0025] The third limiting structure includes: a fifth limiting portion located on the output mechanism of the speed reducer and a sixth limiting portion formed by extending from the mounting bracket, and the fifth limiting portion and the sixth limiting portion jointly restrict the axial position of the third bearing.

[0026] As an embodiment, the actuator further includes a housing cover that is fixedly covered on the motor side of the housing and a circuit board that is fixed to the inner side of the housing cover.

[0027] As an embodiment, the actuator further includes: a motor-side encoder;

[0028] The motor-side encoder includes: a motor-side code disk fixed to the rotor and a motor-side encoder reading device fixed to the circuit board;

[0029] Optionally, the motor-side encoder is an absolute encoder.

[0030] As an embodiment, the actuator further includes: an output-side encoder;

[0031] The output-side encoder includes: an output-side code disk fixed to the output mechanism of the speed reducer, an output-side reading device fixed to the housing, and the output-side reading device is connected to the circuit board through a wire;

[0032] Optionally, the output-side encoder is an absolute position encoder, the output-side code disk is a hollow circular magnet, and is radially magnetized with two magnetic poles;

[0033] The output-side reading device includes: a first Hall sensor and a second Hall sensor, the first Hall sensor is a linear Hall sensor; the second Hall sensor is a linear Hall sensor or a switch Hall sensor.

[0034] As an embodiment, the actuator further includes a digital compass;

[0035] The digital compass is fixed to the circuit board;

[0036] Optionally, the digital compass is a three-axis magnetic field digital compass.

[0037] As an embodiment, the rotor shaft is of a hollow structure;

[0038] Optionally, a heat dissipation structure is further provided on the outer side of the housing;

[0039] Optionally, the heat dissipation structure includes one or any combination of the following: a liquid cooling device sleeved on the housing, a heat dissipation sleeve sleeved on the housing, and heat dissipation fins integrally formed with the housing;

[0040] Optionally, the housing is a hollowed-out housing. Brief Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. It can be understood that the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0042] Figure 1 It is a schematic cross-sectional view of an actuator provided by an embodiment of the present invention;

[0043] Figure 2 It is an exploded schematic view of an actuator provided by an embodiment of the present invention;

[0044] Figure 3 It is a schematic structural view of an output-side encoder provided by an embodiment of the present invention;

[0045] Figure 4 It is a schematic structural view of a motor provided by an embodiment of the present invention;

[0046] Figure 5 It is a schematic structural view of a stator provided by an embodiment of the present invention;

[0047] Figure 6 It is a schematic structural view of a rotor provided by an embodiment of the present invention;

[0048] Figures 7 to 12 It is a schematic diagram of the torque performance simulation effect of a motor provided by an embodiment of the present invention;

[0049] Wherein: 1 - actuator, 2 - motor, 3 - reducer, 4 - housing, 5 - housing cover, circuit board 11, 21 - stator, 211 - stator limiting groove, 22 - rotor, 221 - annular rotor cavity, 222 - rotor shaft, 41 - mounting bracket, 411 - reducer mounting cavity, 31 - sun gear, 32 - planetary gear, 33 - internal gear ring, 34 - flange planetary carrier, 121 - first bearing, 122 - second bearing, 123 - third bearing, 1241 - first limiting portion, 1242 - second limiting portion, 1243 - third limiting portion, 1244 - fourth limiting portion, 1245 - fifth limiting portion, 1246 - sixth limiting portion, 42 - cover screw, 43 - screw hole, 13 - motor side encoder, 131 - motor side code disk, 132 - motor side encoder reading device, 14 - output side encoder, 141 - output side code disk, 142 - output side encoder reading device, 143 - wire, 1421 - output side first Hall sensor, 1422 - output side second Hall sensor, 1423 - output side encoder circuit board, 210 - stator core, 212 - stator yoke, 213 - stator tooth, 214 - winding coil, 223 - permanent magnet, 224 - permanent magnet carrier. Detailed implementation manners

[0050] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0051] In order to enable those skilled in the art in the technical field to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0052] In this disclosure, unless otherwise stated, the directional terms such as "inside" and "outside" refer to "inside" and "outside" relative to the contour of the corresponding component itself. In addition, the terms "first", "second", "third", etc. used in this disclosure are used to distinguish one element from another element, and do not have sequentiality and importance. In addition, in the following description, when referring to the accompanying drawings, unless otherwise explained, the same reference numerals in different drawings represent the same or similar elements. The above definitions are only used to explain and illustrate this disclosure and should not be construed as a limitation to this disclosure.

[0053] As Figures 1 to 3As shown in the figure, an embodiment of the present invention provides an actuator 1, which can be applied to small and micro robots. The actuator 1 includes: a motor 2, a reducer 3, a housing 4, a housing cover 5, and a circuit board 11. The motor 2 is an inner rotor motor, including: a stator 21, a rotor 22 having an annular rotor cavity 221, and a rotor shaft 222 fixedly connected to or integrally formed with the rotor. The main body of the housing 4 is cylindrical. One end of the housing 4 extends inward to form a mounting bracket 41, and the mounting bracket 41 encloses a reducer mounting cavity 411. A stator mounting cavity is formed between the mounting bracket 41 and the side wall of the housing 4. The stator 21 is disposed in the stator mounting cavity. The reducer 3 is connected to the rotor shaft 222 and is disposed in the reducer mounting cavity 411. At least part of the reducer mounting cavity 411 is located in the annular rotor cavity 221. In the embodiment of the present invention, an inner rotor motor is adopted. The rotor has an annular rotor cavity. The housing is circular and is formed with a mounting bracket. The reducer is connected to the rotor and is disposed in the reducer mounting cavity enclosed by the mounting bracket, and at least part of the reducer mounting cavity is located in the annular rotor cavity, so that at least part of the axial space can be reused by the reducer and the rotor, thereby reducing the overall volume of the actuator. Moreover, in this embodiment, the stator that generates heat during operation is directly fixed to the housing, and the heat dissipation effect is better than that of the existing QDD actuator, which is beneficial to meeting the application requirements of high-performance small and micro robots.

[0054] The reducer 3 includes an input mechanism, a reduction mechanism, and an output mechanism. Optionally, in this embodiment, as Figure 4 shown, the inner diameter d2 of the stator 21 is greater than or equal to 75% of the outer diameter d1 of the stator 21. Optionally, in this embodiment, the diameter of the annular rotor cavity 41 is greater than or equal to 60% of the outer diameter d1 of the stator. Thereby, the stator 21 has a large annular cavity, which is convenient for the reducer 3 and the rotor 22 to reuse the annular cavity of the stator 21, improving the space utilization rate. In this embodiment, the reducer 3 is a single-stage planetary reducer. The input mechanism is a sun gear 31. The reduction mechanism includes planetary gears 32 and an internal gear ring 33. The output mechanism is a planet carrier. The sun gear 31 is fixed to the rotor shaft 222. The planetary gears 32 are meshed with the sun gear 31 and the internal gear ring 33. The internal gear ring 33 is fixed to the mounting bracket 41. The planetary gears 32 are disposed on a support step formed by the extension of the mounting bracket 41. In this embodiment, as Figure 1 shown, most of the reduction mechanism of the reducer is located in the annular rotor cavity 221, but it is not limited thereto. In some examples, the reduction mechanism of the reducer can also be entirely located in the annular rotor cavity 221, making the actuator more compact. Preferably, as Figure 1 shown, in this embodiment, the planet carrier and the output flange are integrally formed into a flange planet carrier 34, which is convenient for fixing a connecting rod or other components to the flange planet carrier 34. Optionally, the reduction ratio of the reducer 3 can be greater than or equal to 3 and less than or equal to 10, so that the actuator has better dynamic performance and a reasonable torque-speed output curve.

[0055] In this embodiment, the stator 21 is disposed in the stator mounting cavity. Optionally, the stator 21 can be fixed to the side wall of the housing 4. By way of example and not limitation, the stator 21 and the housing 4 can be fixed with a thermally conductive glue to improve the heat dissipation performance of the actuator. In this embodiment, by way of example and not limitation, the stator 21 is further provided with a stator limiting groove 211 for passing through and limiting the wire 143 of the output side encoder 14. The rotor 22 is coaxially arranged with the stator 21. Optionally, in this embodiment, the rotor 22, the mounting bracket 41, and the output mechanism of the speed reducer 3 are coaxially arranged and axially limited. The mounting bracket 41 and the output mechanism of the speed reducer 3 are coaxially arranged and axially limited. Specifically, the actuator 1 is provided with a first bearing 121, a second bearing 122, and a third bearing 123. The rotor 22 and the mounting bracket 41 are fixedly engaged through the first bearing 121; the output mechanism of the speed reducer 3 and the rotor 22 are fixedly engaged through the second bearing 122; the output mechanism of the speed reducer 3 and the mounting bracket 41 are fixedly engaged through the third bearing 123; the actuator 1 further includes a first limiting structure for defining the axial position of the first bearing 121, a second limiting structure for defining the axial position of the second bearing 122, and a third limiting structure for defining the axial position of the third bearing 123. Optionally, in this embodiment, the first limiting structure includes: a first limiting portion 1241 located on the rotor 22 and a second limiting portion 1242 formed by extending the mounting bracket 41. Optionally, the first limiting portion 1241 is a snap ring provided on the rotor 22, and the second limiting portion 1242 is a limiting step formed by extending the mounting bracket 41. The first bearing 121 can be fixed to the second limiting portion 1242 by glue or the like, and the axial position of the first bearing 121 is jointly restricted by the first limiting portion 1241 and the second limiting portion 1242. The second limiting structure includes: a third limiting portion 1243 provided on the output mechanism of the speed reducer 3 and a fourth limiting portion 1244 provided at the rotor shaft 222. The third limiting portion 1243 is a limiting step formed on the flange planet carrier 34, and the fourth limiting portion 1244 is a snap ring located on the rotor shaft 222. The second bearing 122 can be fixed to the third limiting portion 1243 by glue, and the axial position of the second bearing 122 is jointly restricted by the third limiting portion 1243 and the fourth limiting portion 1244. The third limiting structure includes: a fifth limiting portion 1246 located on the output mechanism of the speed reducer 3 and a sixth limiting portion 1246 formed by extending the mounting bracket 41. The fifth limiting portion 1245 is an annular flange formed on the flange planet carrier 34, and the sixth limiting portion 1246 is a limiting step formed by extending the mounting bracket 41. The axial position of the third bearing 123 is jointly restricted by the fifth limiting portion 1245 and the sixth limiting portion 1246. It can be understood that in practical applications, the axial limiting of the first bearing, the second bearing, and the third bearing can also be achieved by other means, and the specific axial limiting method in this embodiment is not specifically limited.

[0056] In this embodiment, most of the reduction mechanism of the speed reducer 3 is located within the annular rotor cavity 221. In other examples, the reduction mechanism of the speed reducer 3 can also be entirely located within the annular rotor cavity 221, thereby significantly reducing the axial length of the actuator, improving the space utilization rate, and reducing the volume of the actuator.

[0057] Optionally, as Figure 1 , 2 shown, the housing cover 5 can be fixedly covered on the motor side of the outer housing 4 through the cover screws 42. The housing cover 5 can also be fixed to the outer housing 4 by glue. In this embodiment, the outer housing 4 has a plurality of screw holes 43, and the outer housing 4 is fixed to an external base or other components through the screw holes 43 and screws matching the screw holes 43. The present invention does not limit the fixing method of the outer housing 4 or the housing cover 5 to the external base or other components. Optionally, in one embodiment, the outer housing 4 can be made of aluminum alloy and provided with a weight-reducing hollow groove on the output side, thereby further reducing the weight of the actuator.

[0058] As Figure 2 shown, in this embodiment, the circuit board 11 is fixed to the inner side of the housing cover 5. By way of example and not limitation, the circuit board 11 and the housing cover 5 can be fixed by glue. The circuit board 11 can integrate a drive module for controlling the motor, a communication module with a host computer, a power connector, and a communication connector. The present invention does not limit the fixing method of the circuit board 11 to the housing cover 5 and the functions of the circuit board 11.

[0059] As Figures 1 to 2 shown, in this embodiment, the actuator 1 includes a motor-side encoder 13 and an output-side encoder 14. The motor-side encoder 13 includes: a motor-side coding disk 131 fixed to the rotor 22 and a motor-side encoder reading device 132 fixed to the circuit board 11. Optionally, the motor-side encoder 13 can be an absolute encoder. In this embodiment, the motor-side coding disk 131 is a two-pole hollow magnet with radial magnetization, which is fixed in the hollow groove of the rotor 22 on the side close to the circuit board 11 of the motor, and the motor-side encoder reading device 132 is an integrated circuit chip with a Hall sensor. In this embodiment, the motor-side encoder can be classified according to the principle and includes but is not limited to magnetic encoders, inductive encoders, capacitive encoders, and optical encoders. According to the function, it can include absolute position encoders and incremental encoders. The structure of the motor-side encoder includes but is not limited to: non-contact shaft encoders and non-contact hollow encoders. The present invention does not limit this.

[0060] The output-side encoder 14 includes: an output-side coding disk 141 fixed to the output mechanism of the speed reducer and an output-side encoder reading device 142 fixed to the outer housing. The output-side encoder reading device 142 is connected to the circuit board 11 through a wire.

[0061] Optionally, the output - side encoder 14 can be an absolute - position encoder. Specifically, the output - side encoding disk 141 is a hollow circular magnet, and is radially magnetized with two magnetic poles. The output - side encoder reading device 142 can include: a first Hall sensor and a second Hall sensor. The first Hall sensor is a linear Hall sensor that outputs an analog signal; the second Hall sensor is a linear Hall sensor or a switching Hall sensor that outputs an analog or digital signal. As Figures 1 to 3 shown, in this embodiment, the output - side encoding disk 141 is a hollow magnet sleeved on the outer ring of the flange planet carrier 34. The output - side encoder reading device 142 is fixed to the housing 4 and is located on the outer side of the output - side encoding disk 141 in the radial direction. The wire 143 of the output - side encoder 14 passes through the inner cavity of the housing 4, passes through the stator limiting groove 211, and is fixed and connected to the circuit board 11. In this embodiment, the output - side encoder 14 can be the same as or different from the motor - side encoder, which will not be elaborated here. This embodiment does not limit the type of the output - side encoder.

[0062] As Figure 3 shown, in this embodiment, the output - side encoder 14 is an absolute - position encoder. The output - side encoding disk 141 is a hollow circular magnet, and is radially magnetized with two magnetic poles. The output - side encoder reading device 142 includes: an output - side first Hall sensor 1421 and an output - side second Hall sensor 1422. Among them, the output - side first Hall sensor 1421 is a linear Hall sensor that outputs an analog signal according to the magnetic - pole direction and magnetic - field magnitude generated by the output - side encoding disk 141; the output - side second Hall sensor 1422 is a linear Hall sensor or a switching Hall sensor that outputs an analog signal or a digital signal. In this embodiment, by way of example and not limitation, the output - side first Hall sensor 1421, the output - side second Hall sensor 1422, and the wire 143 of the output - side encoder are simultaneously fixed on the output - side encoder circuit board 1423; the circuit board 11 is provided with a device for processing the signals generated by the output - side first Hall sensor 1421 and the output - side second Hall sensor 1422 and converting them into the absolute - position information of the flange planet carrier 34 relative to the housing 4.

[0063] Optionally, in another embodiment, the actuator 1 can further include a digital compass fixed to the circuit board 11. Optionally, the digital compass can be a three - axis magnetic - field digital compass for detecting the direction and motion state of the actuator in space.

[0064] Optionally, in another embodiment, the rotor shaft 222 is a hollow structure to facilitate threading of cables, signal lines, and other lines, etc.

[0065] Optionally, in another embodiment, a heat dissipation structure (not shown in the figure) is further provided outside the housing 4. Optionally, the heat dissipation structure may include one or any combination of the following: a liquid cooling device sleeved on the housing, a heat dissipation sleeve sleeved on the housing, heat dissipation fins integrally formed with the housing, and other housing structures that increase the contact area with the environment. The adoption of the heat dissipation structure can effectively improve the maximum power, rated power, maximum torque, and rated torque of the actuator.

[0066] Optionally, in this embodiment, the motor constant of the motor 2 is greater than or equal to 1.5 Nm / kg√(w), so that the actuator has higher performance and lighter weight. The definition of the motor constant is:

[0067]

[0068] The specific structure of the motor 2 to achieve the aforementioned motor constant is as follows:

[0069] As Figures 4 to 5 shown, the motor 2 is a fractional-slot inner-rotor motor. The motor 2 includes: a stator 21 and a rotor 22. Among them, the stator 21 includes a stator core 210 and a stator winding. In this embodiment, the stator core 210 includes: a stator yoke 212 and stator teeth; the stator teeth include: a plurality of stator teeth 213 provided on the stator yoke 212. In this embodiment, the stator core 210 is an integral structure. By way of example and not limitation, the stator core 210 may be laminated from silicon steel sheets or soft magnetic material sheets. The stator winding includes a preset number of winding coils 214 formed by machine winding. The stator winding is a concentrated winding, that is, the pitch of the winding coils is 1, and each winding coil 214 is correspondingly sleeved on one rather than multiple stator teeth 213. In this embodiment, an insulating layer is provided on the surface of the stator teeth to ensure the insulation between the stator winding and the stator core. In this embodiment, each stator tooth is sleeved with 1 or more winding coils 214. As Figure 4 shown, one winding coil is sleeved on each stator tooth. As an alternative implementation, two winding coils may be sleeved on each stator tooth. The number of winding coils sleeved on each stator tooth in this embodiment is not specifically limited.

[0070] In this embodiment, after the winding coils are separately processed by machine winding, they can be sleeved and installed on the stator teeth and can be connected by welding to form a stator winding. Alternatively, multiple connected winding coils can also be directly wound by machine. The connection method between the winding coils in this embodiment is not specifically limited. By way of example and not limitation, in this embodiment, the number of winding coils included in the stator winding can be determined according to the number of stator teeth and the number of winding coils sleeved on each stator tooth. For example, when the number of stator teeth of the motor is 48 and 2 winding coils are sleeved on each stator tooth, the stator winding includes 96 winding coils.

[0071] As Figure 6 shown, in this embodiment, the rotor 22 of the permanent magnet brushless motor includes: a permanent magnet 223 and a permanent magnet carrier 224, wherein the permanent magnet is used for exciting to generate a rotating magnetic field.

[0072] Optionally, in this embodiment, from the tooth end away from the stator yoke 212 to the tooth root close to the stator yoke 212, the width of the stator teeth is the same everywhere, which is convenient for the manufacture of the corresponding winding coils 214, and can improve the space utilization rate, thereby enhancing the motor constant density. It can be understood that in some examples, from the tooth end away from the stator yoke 212 to the tooth root close to the stator yoke 212, the widths of the stator teeth can also gradually increase. It should be noted that in the prior art, the stator teeth are generally of an inverted T-shaped structure (i.e., the stator teeth have a boot structure), and the stator teeth with boots will affect the size of the winding coil cavity, thereby reducing the space utilization rate of the winding coils. In this embodiment, the cancellation of the stator tooth boots improves the space utilization rate of the winding coils, which is beneficial to further improving the motor constant density.

[0073] On the basis of the above embodiment, this embodiment further improves the size structure of the motor 2, specifically as follows:

[0074] In this embodiment, the width w at the narrowest part of the stator teeth is greater than or equal to 30% of the stator inner circumference / N and less than or equal to 65% of the stator inner circumference / N, where N is the number of stator teeth 213, and the diameter of the stator inner circle is the stator inner diameter d1. In this embodiment, N = 48. As Figure 7 shown, it is a simulation effect schematic diagram of the stator tooth width / (stator inner circumference / number of teeth) and the motor constant density. The thickness L of the stator yoke is greater than or equal to 30% of the width w at the narrowest part of the stator teeth and less than or equal to 250% of the width w at the narrowest part of the stator teeth. As Figure 8 shown, it is a simulation effect schematic diagram of the stator yoke thickness / stator tooth width and the motor constant density. The inner diameter d1 of the stator core is greater than or equal to 75% of the outer diameter d2 of the stator core and less than or equal to 90% of the outer diameter d2 of the stator core. As Figure 9 shown, it is a simulation effect schematic diagram of the ratio of the inner diameter of the stator core to the outer diameter of the stator core and the motor constant density. The axial height of the stator core is less than or equal to 20% of the outer diameter d2 of the stator. As Figure 10 shown, it is a simulation effect schematic diagram of the stator core height / stator outer diameter and the motor constant density. An air gap is formed between the stator 21 and the rotor 22, and the average air gap distance g of the motor is less than or equal to 0.7% of the outer diameter d2 of the stator. As Figure 11As shown, it is a schematic diagram of the simulation effect of the ratio of the average air gap distance to the outer diameter of the stator and the motor constant density. The average radial thickness t of the permanent magnet is less than or equal to 30 times the average air gap distance g and greater than or equal to 2 times the average air gap distance g. As Figure 12 shown, it is a schematic diagram of the simulation effect of the ratio of the average radial thickness of the permanent magnet to the average air gap distance and the motor constant density.

[0075] It should be noted that the further optimization of the above structural dimensions and the like in this embodiment is proposed by the inventor after comprehensive consideration of factors such as the difficulty of process implementation and the electromagnetic performance of the motor. By making the above optimizations to the relevant dimensions of the motor in this embodiment, the manufacturing, processing, and assembly of the motor are made easier, and it is beneficial to increase the slot fill factor, enlarge the air gap area, and improve the electromagnetic performance, thereby increasing the motor constant density of the permanent magnet brushless motor.

[0076] As Figure 6 shown, in this embodiment, the permanent magnet 223 is disposed on one side surface of the permanent magnet carrier 224 opposite to the stator 1. The permanent magnet 223 can be made of neodymium iron boron magnet.

[0077] As an implementation manner, in this embodiment, the permanent magnet 223 includes a plurality of permanent magnet blocks, and each permanent magnet block is attached to the surface of the permanent magnet carrier 224, that is, the permanent magnet block is a surface-mounted permanent magnet block.

[0078] As another implementation manner, the permanent magnet 223 can be an integral ring structure and is sleeved and fixed on the surface of the permanent magnet carrier 224. The permanent magnet 223 can be fixed to the permanent magnet carrier 224 by glue.

[0079] Optionally, in this embodiment, the permanent magnet carrier 224 is a rotor core made of soft magnetic material. As another implementation manner, the permanent magnet carrier 224 can also be a non-soft magnetic material. By way of example and not limitation, the material of the permanent magnet carrier 224 can be aluminum alloy. The weight of the permanent magnet carrier 224 made of aluminum alloy is significantly reduced compared to the rotor core made of soft magnetic material, thereby increasing the motor constant density.

[0080] Optionally, in this embodiment, a plurality of permanent magnet blocks can form a Halbach array.

[0081] In this embodiment, the installation of the permanent magnet 223 on the surface of the permanent magnet carrier 224, compared with the permanent magnet embedded in the permanent magnet carrier 224, not only makes the manufacturing process simpler and the motor weight smaller, but also can reduce the influence of the coil current on the rotating magnetic field, making the induction linearity of the motor better, so that the motor is easier to control and runs more smoothly. The reluctance torque of the permanent magnet brushless motor in this embodiment is less than or equal to the larger value of 10% of the rated torque and 5% of the peak torque, thereby ensuring the stability of the motor operation.

[0082] In this embodiment, the motor can be a three-phase motor, and the ratio of the number of teeth and poles of the motor is an integer multiple of 12 / 10 or 12 / 14; among them, the number of magnetic poles of the permanent magnet 223 can be 40, and this ratio of the number of teeth and poles can effectively reduce the cogging torque and make the motor run smoothly.

[0083] It should be noted that the structure of the motor 2 involved in this embodiment can also refer to the invention patent application with the application number 202010330604.8 filed by the applicant on April 24, 2020, and this patent application is incorporated herein by reference in its entirety.

[0084] The motor constant per unit mass in this embodiment can reach which is significantly improved compared with the prior art. When the motor weights are equal or similar, under the same working voltage and good heat dissipation conditions, the power output density of the permanent magnet brushless motor in this embodiment can reach 12 kw / kg.

[0085] The present invention also provides a robot, including the actuator as described above.

[0086] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes can be made in form and details without departing from the spirit and scope of the present invention.

Claims

1. An actuator, characterized in that, Applied to small or micro robots, including: a housing, a motor, and a speed reducer; The motor is an inner rotor motor, including: a stator, a rotor having an annular rotor cavity, and a rotor shaft fixedly connected to or integrally formed with the rotor; One end of the housing extends inward to form a mounting bracket, the mounting bracket encloses a speed reducer mounting cavity, a stator mounting cavity is formed between the mounting bracket and the side wall of the housing, and the stator is disposed in the stator mounting cavity; the speed reducer is connected to the rotor shaft and is disposed in the speed reducer mounting cavity, and at least part of the speed reducer mounting cavity is located in the annular rotor cavity; The diameter of the annular rotor cavity is greater than or equal to 60% of the outer diameter of the stator; The actuator further includes: a first bearing, a second bearing, and a third bearing; The rotor and the mounting bracket are fixedly fitted through the first bearing; The output mechanism of the speed reducer and the rotor are fixedly fitted through the second bearing; The output mechanism of the speed reducer and the mounting bracket are fixedly fitted through the third bearing.

2. The actuator according to claim 1, characterized in that, The ratio of the motor constant of the motor to the motor weight is greater than or equal to 1.5 Nm / kg√(w).

3. The actuator according to claim 1, characterized in that, The inner diameter of the stator is greater than or equal to 75% of the outer diameter of the stator.

4. The actuator according to claim 1, wherein, The speed reducer is a single-stage planetary speed reducer.

5. The actuator according to claim 4, characterized in that, The reduction ratio of the speed reducer is greater than or equal to 3 and less than or equal to 10.

6. The actuator according to claim 4, characterized in that, Part or all of the reduction mechanism of the single-stage planetary speed reducer is located in the annular rotor cavity.

7. The actuator according to claim 4, wherein The input mechanism of the single-stage planetary speed reducer is a sun gear, and the sun gear is fixed to the rotor shaft; The reduction mechanism of the single-stage planetary speed reducer includes: an internal gear ring fixed to the mounting bracket and planetary gears meshing with the sun gear and the internal gear ring, and the planetary gears are disposed on a support step formed by the extension of the mounting bracket.

8. The actuator according to any one of claims 4 to 7, characterized in that The output mechanism of the speed reducer is a planet carrier.

9. The actuator according to claim 8, characterized in that, The actuator further includes an output flange, and the planet carrier and the output flange are integrally formed into a flange planet carrier.

10. The actuator according to claim 1, characterized in that, The actuator further includes a first limiting structure for limiting the axial position of the first bearing, a second limiting structure for limiting the axial position of the second bearing, and a third limiting structure for limiting the axial position of the third bearing.

11. The actuator according to claim 10, wherein The first limiting structure includes: a first limiting portion on the rotor and a second limiting portion formed by the extension of the mounting bracket, and the first limiting portion and the second limiting portion jointly restrict the axial position of the first bearing.

12. The actuator according to claim 10, wherein The second limiting structure includes: a third limiting portion provided on the output mechanism of the speed reducer and a fourth limiting portion provided at the rotor shaft, and the third limiting portion and the fourth limiting portion jointly restrict the axial position of the second bearing.

13. The actuator according to claim 10, characterized in that, The third limiting structure includes: a fifth limiting portion on the output mechanism of the speed reducer and a sixth limiting portion formed by the extension of the mounting bracket, and the fifth limiting portion and the sixth limiting portion jointly restrict the axial position of the third bearing.

14. The actuator according to claim 1, characterized in that, The actuator further includes a housing cover fixedly attached to the motor side of the housing and a circuit board fixed to the inner side of the housing cover.

15. The actuator according to claim 14, characterized in that, The actuator further includes: a motor side encoder; The motor-side encoder includes: a motor-side code disk fixed to the rotor and a motor-side encoder reading device fixed to the circuit board.

16. The actuator according to claim 15, wherein The motor-side encoder is an absolute encoder.

17. The actuator according to claim 14, wherein The actuator further includes: an output-side encoder; The output-side encoder includes: an output-side code disk fixed to the output mechanism of the speed reducer, an output-side reading device fixed to the housing, and the output-side reading device is connected to the circuit board through a wire.

18. The actuator according to claim 17, wherein The output-side encoder is an absolute position encoder, the output-side code disk is a hollow circular magnet and is magnetized radially with two magnetic poles; the output-side reading device includes: a first Hall sensor and a second Hall sensor, the first Hall sensor is a linear Hall sensor; the second Hall sensor is a linear Hall sensor or a switch Hall sensor.

19. The actuator according to claim 14, characterized in that, The actuator includes: a digital compass.

20. The actuator according to claim 19, characterized in that, The digital compass is a three-axis magnetic field digital compass and is fixed to the circuit board.

21. The actuator according to claim 1, characterized in that, The rotor shaft is of a hollow structure.

22. The actuator according to claim 1, characterized in that, A heat dissipation structure is further provided on the outer side of the housing.

23. The actuator according to claim 22, wherein, The heat dissipation structure includes one or any combination of the following: a liquid cooling device sleeved on the housing, a heat dissipation sleeve sleeved on the housing, and heat dissipation fins integrally formed with the housing.

24. The actuator according to claim 1, characterized in that, The housing is a hollowed-out housing.

25. A robot, comprising the actuator according to any one of claims 1 to 24.

Images