Miniature NGW multi-stage planetary gear speed reducing motor

Abstract

The invention is suitable for the technical field of miniature NGW speed reducing motor structures, and discloses a miniature NGW multi-stage planetary gear speed reducing motor which comprises a motor and a miniature NGW multi-stage planetary speed reducer installed at one end of the motor. The planetary reducer comprises a shell, a planetary reducing mechanism arranged in the shell and an output shaft, one end of the output shaft extends out of the shell, the other end of the output shaft penetrates through the shell and is connected with one end of the planetary reducing mechanism, a motor is provided with a driving shaft, one end of the driving shaft penetrates through the shell and is connected with the other end of the planetary reducing mechanism, and the length-diameter ratio t of the motor meets the relation that t is larger than or equal to 1 and smaller than or equal to 2; the ratio y of the diameter of the speed reduction motor to the diameter of the speed reduction box meets the relation that y is larger than 0.95 and smaller than 1.05, the transmission ratio i of the planetary speed reduction mechanism meets the relation that i is larger than or equal to 40 and smaller than or equal to 360, and the ratio k of the axial length of the shell to the outer diameter of the shell meets the relation that k is larger than 0 and smaller than 1. The planetary gear reduction motor provided by the invention not only meets the design requirement of large transmission ratio of the planetary gear reduction motor, but also reduces the length-diameter ratio of the planetary reducer.

Description

Technical Field

[0001] The present invention relates to the technical field of reduction motor structures, and in particular to a micro NGW multi-stage planetary gear reduction motor. Background Art

[0002] A micro NGW multi-stage reduction motor is a combination of a micro motor and a reducer. Specifically, a micro NGW multi-stage motor is small in size, capacity, and output power. Currently, the most popular micro reduction motors on the market are mainly divided into two types: fixed-axis gear type and planetary gear type. Planetary gear type micro reduction motors are increasingly widely used due to their compact structure and large transmission ratio.

[0003] In the planetary gear reduction motor industry, usually the micro NGW multi-stage planetary gear reduction motor is In 38mm the following In this field, for common miniature NGW multi-stage planetary gear reduction motors, the best a person skilled in the art can do is to design a planetary gear reducer with an aspect ratio between 1.5 and 3.0. Conventional designs only meet the technical effect of "almost working". However, those skilled in the art will know that, under the premise of meeting the requirements of reduction motors of the same size and type (diameter <38mm), it is actually a technical problem that this field has sought to solve but has struggled to overcome to achieve a smaller aspect ratio, thereby increasing the output torque, extending the service life of the planetary gear trains at all levels, increasing the overall load, reducing vibration, reducing noise, and reducing weight.

[0004] Because the NGW planetary gearbox has a graded feature and can be combined with different transmission ratios, it can flexibly adapt to the needs of service terminals and become a relatively standardized product. However, the current reduction gearboxes or reduction motors on the market have problems with unreasonable matching with the motor, or are noisy or insufficient in strength. Their overall length is significantly longer than that of the fixed-axis reduction gearbox or reduction motor of the same model. In the existing NGW planetary gear micro reduction motor, the reducer mainly has the following two structural design schemes:

[0005] 1) The first solution is: except for the primary plastic planetary gears (usually nylon or POM materials) to moderately reduce noise, the rest of the planetary reduction components are made of metal materials, and the planetary support columns on the planetary frame are mostly combined (the embedded columns will increase the height of the planetary frame flange, otherwise it will be unstable), and the shell is also usually made of metal materials. The height of the planetary gears and the height of the planetary frame inside are not further optimized, and the difference in strength of each level (equal strength design means equal safety factor) and equal life design are not considered in detail. The basis for matching with the motor power is also insufficient. This type of reducer not only has a small load capacity but is also relatively heavy and lengthy as a whole; its length exceeds that of the fixed-axis reducer of the same model, which runs counter to the principle of power diversion and small size of planetary transmission. Patent CN201150022Y belongs to this common category on the market.

[0006] 2) The second solution is: all levels of planetary reduction components are made of plastic materials, and the design of the metal planetary reduction box is completely copied, and the incremental effect of the torque strength of each layer is not considered. This will cause insufficient strength at the output end, weak impact bearing capacity, and the wear life will first fail at the level close to the output shaft end (Patent CN207093680 U belongs to this situation. The core idea of ​​using plastic materials is to reduce costs, and the deep-seated principles of the planetary reduction box are not understood). Some designs adopt the design of supporting the planetary gears at both ends of the planetary frame for fear of insufficient load of the planetary frame (Patent CN203067760U belongs to this situation), which greatly lengthens the axial length of the reduction box. Even if the planetary frame body still adopts the design of cantilever beam supporting the planetary gear, there is a lack of theoretical and experimental basis for the optimization of the thickness of the planetary frame, the thickness of the gear, and the module, resulting in a slender reduction box, and unable to carry large loads and the micro brushed motor cannot reasonably power. Matching, when using plastic materials, it is necessary to take into account factors such as strength, temperature, precision, wear life between relative materials, grease, thermal expansion and contraction. Therefore, there are very few manufacturers who can independently develop plastic planetary reducers, because each test verification requires mold opening, and the R&D investment is large. Since the strength of plastic and metal is not on the same order of magnitude, the practical value of a purely all-plastic reducer is not high. Even if it can be used, it is very long and cannot work for a long time under high temperature and high load. In particular, life verification requires a large number of tests on different materials and temperatures to obtain reliable and effective data. Summary of the Invention

[0007] The object of the present invention is to provide a micro planetary gear reduction motor, which aims to solve the technical problem of the existing micro planetary gear reduction motor being too long.

[0008] To achieve the above-mentioned purpose, the present invention provides a solution: a miniature NGW multi-stage planetary gear reduction motor, comprising a motor and a planetary reducer installed at one end of the motor, the motor being a DC brushed motor, the ratio t of the axial length to the diameter of the reduction motor satisfying the relationship: 1≤t≤2, the ratio y of the diameter of the reduction motor and the reduction box satisfying the relationship: 0.95<y<1.05, the planetary reducer comprising a housing, a planetary reduction mechanism disposed in the housing, and an output shaft having one end extending outside the housing and the other end passing through the housing and connected to one end of the planetary reduction mechanism, the motor having a drive shaft having one end passing through the housing and connected to the other end of the planetary reduction mechanism, the transmission ratio i of the planetary reduction mechanism satisfying the relationship: 40≤i≤360, and the ratio k of the axial length of the housing to the outer diameter of the housing satisfying the relationship: 0<k<1.

[0009] It should be noted that this field does not refer to all planetary gear reduction motors, but to micro planetary gear reduction motors, and the limited parameters are aspect ratio range 0-1, transmission ratio range 40-360, reduction motor and reducer box diameter ratio range 0.95-1.05, micro reduction motor axial length and diameter ratio range 1-2. It is a universal standard solution derived and tested based on equal strength, equal life, low noise between multi-stage planetary gears, and reasonable matching and power matching with general micro brushed DC motors and reduction diameters. The range of aspect ratio is related to volume miniaturization and motor matching. First of all, the design of micro brushed DC motors originated from abroad, and also has the concept of aspect ratio. It has now formed an industry standard. The domestic reference is mainly Japan's Mabuchi Motor Co., Ltd. Motor), the brush DC motor is too short in axis (i.e., the aspect ratio is less than 1), and the commutator, bearings, etc. have a larger proportion of the allocated length in the axial direction, so the length of the effective work (magnetic induction) becomes less, and it is not suitable for the core requirement of energy conversion in the smallest possible volume. When the length of the motor is too long (for example, greater than 2), the dynamic balance decreases under the force of the magnetic field due to the longer rotating shaft of the motor, and the longer the motor shaft, the more difficult it is to process, the manufacturing cost and process cost also increase significantly, and the accuracy is not easy to guarantee. Therefore, the aspect ratio of the existing micro DC brush motor is basically in the range of 1 to 2. Due to the characteristics of the brush motor, it cannot generate high torque at low speed (usually less than 2000 rpm), so it needs to match the deceleration to achieve the effect. Due to the professionalism of transmission design, it is difficult for general manufacturers to have professional design and manufacturing capabilities, so a relatively specialized standardized reducer has emerged. The same situation occurs in the industrial field (such as industrial planetary reducers, RV reducers and harmonic reducers). Due to N GW planetary reduction transmissions have graded characteristics, making them universally applicable when matching motors to achieve the required terminal output torque and speed. From a design perspective, matching the reducer diameter to the motor diameter is the most universally applicable and also offers a relatively small surface area. Just as the concept of an aspect ratio is used in the manufacture of micro brushed motors, this application also proposes an aspect ratio and constrains it to be less than 1. This 1 is actually related to the maximum power and lifespan of micro brushed motors of the same diameter. Brushed DC motors typically have a speed range of 2000 to 20,000 rpm. Higher speeds increase power but shorten lifespan (due to brush commutation and contact wear), while lower speeds increase lifespan. This aspect ratio of 1, when the reducer's longest length is equal to its diameter, meets the requirements for matching a brushed motor with a shorter lifespan corresponding to maximum power and a relatively long lifespan at low speeds. This is the result of a combination of theoretical derivation and experimentation (the reducer bodies corresponding to the micro standard reducers marketed by various companies are far higher than this value).For example, a commonly used 20mm miniature brushed DC motor has a standard model number of 180 and a length of approximately 32mm. Based on current manufacturing standards, its power conversion efficiency is unlikely to exceed 70%, and therefore its upper power limit corresponding to its volume is approximately 10W (at room temperature, the heat generated by unworked work is balanced with the heat dissipation generated by the volume and does not damage the motor). Therefore, the matching length of the reduction gearbox under the same diameter conditions requires theoretical calculation, design, and experimentation. Another key indicator here is the safety factor. What should the safety factor be at each level (equal strength, i.e., equal safety factor)? This requires not only theoretical design but also experimental testing and verification. The applicant's testing content includes: static destructive torque testing at each level (the method is to lock the primary sun gear to load the output shaft to destruct torque and lock the output end to load the input end to destruct), impact strength destructive testing (testing impact destructiveness by locking the output end for different time periods), normal operating temperature rise testing, maximum output power temperature rise testing, continuous and discontinuous operating life testing, etc. These verification tests in the field of miniature reduction motors cannot be completed in a short time and at a low cost.

[0010] The rationality of the transmission ratio is also a complex matter. For example, if the single-stage NGW planetary transmission is designed to be 4:1, then as the transmission level increases, the transmission ratio can be changed to: 16, 64, 256, 1024... Although the speed range of brushed DC motors is usually arbitrarily designed within 2000~20000, the enameled wire wound inside the rotor also has an industrial universal diameter standard (for example: 0.1mm, 0.2mm, etc.), plus the motor speed and torque manufacturing error (usually + / -10%), it is difficult to use a single-stage fixed transmission ratio to meet most working conditions. According to the usual practice, the ratio between adjacent transmission ratios should not exceed 50%, such as 4, 6, 9, 13, 20, 30, 45, 65, 100..., and some even have a smaller ratio between adjacent transmission ratios, but this will increase the development cost. Since micro brushed DC motors have corresponding standards, the speed of micro brushed DC motors of different diameters is different. Shaft diameters also have corresponding standards, thus placing limits on the diameter of the sun gear. The number of teeth and module of the sun gear must also consider factors such as meshing strength, contact, lifespan, and the maximum single-stage transmission ratio. For example, the industry standard shaft diameter for a 20mm micro DC brush motor is 2mm, with sizes 130 (25mm length) and 180 (32mm length). Given a fixed outer diameter for the reduction gearbox, the ring gear pitch diameter can be estimated to be approximately 17mm based on the housing manufacturing process and materials. From a practical perspective, a larger single-stage transmission ratio is preferred, with the maximum transmission ratio primarily determined by the sun gear pitch diameter. Given a 2mm motor shaft diameter, manufacturing difficulty, cost constraints, and gear strength, the sun gear pitch diameter is approximately 3mm, resulting in a maximum transmission ratio of approximately 7. A 24mm diameter micro DC brush motor, with a 2mm shaft diameter, allows for a larger transmission ratio than a single stage, thus limiting the upper limit of a three-stage transmission to 360. Since the three-stage transmission ratio needs to be combined and matched, the lower limit of the single-stage transmission ratio can be 3.5, and the three-stage transmission ratio corresponds to 42.8, with a lower limit of 40. Therefore, the correlation between the transmission ratio and the aspect ratio is the result of a combination of various factors. In practice, the module is 0.35 for the 20cm micro planetary reducer, 0.27 for the 16cm micro reducer, 0.4 for the 24mm micro reducer, 0.5 for the 28mm micro reducer, and 0.63 for the 36mm micro reducer. The minimum number of sun teeth is 9 teeth, which verifies that the comprehensive performance meets the above-mentioned correlation factors. In addition, in the field of micro brushed motors, there is a high sensitivity to the noise of the matching reducer because the noise of the motor itself is relatively small. In addition, most micro reducer motors are suitable for personal care, home use, and other occasions. Balancing noise is particularly important. Therefore, it is usually necessary to make an extremely reasonable balance between torque, speed, life, noise, and volume.

[0011] Furthermore, the micro NGW multi-stage planetary gear reduction motor has an input end sun gear, an input end planetary gear, an input end planetary carrier, an intermediate sun gear, an intermediate planetary gear, an intermediate planetary carrier, an output end sun gear, an output end planetary gear, an output end planetary carrier, and an inner ring gear on the inner side wall.

[0012] Furthermore, the intermediate sun gear and the input-end planet carrier are integrally formed; the output-end sun gear and the intermediate planet carrier are integrally formed.

[0013] It should be noted that, within the common range of planetary gear reduction motors, the common sun gear and the planetary carrier connected thereto are usually two separate structures, which results in the need for an additional connection structure between the sun gear and the planetary carrier (not limited to riveting, interlocking, and screw connection methods). Because they are two separate structures, it is inevitable that the radial length of the two structures will be longer due to the existence of the connection structure. The design provided in this application integrates the sun gear of the upper level and the planetary carrier of the lower level (the intermediate sun gear and the input end planetary carrier are integrally formed; the output end sun gear and the intermediate planetary carrier are integrally formed). In terms of the win, the mold can be opened as an integrated whole, eliminating the need for connectors. Compared with the separate type, replacement is simpler, assembly is more convenient, and the cost is lower. Factors such as noise, vibration, and life can also be greatly reduced. When the aspect ratio range is within the range of 0-1, the integrated design solution in this application can undoubtedly meet this requirement more effectively.

[0014] Furthermore, the hardness of the input-end planetary gear is smaller than the hardness of the intermediate planetary gear, and the elastic modulus of the input-end planetary gear is larger than the elastic modulus of the intermediate planetary gear.

[0015] Furthermore, the hardness of the input-end planetary gear is 52 Shore D to 72 Shore D in Shore hardness, and the elastic modulus is 300 MPa to 800 MPa.

[0016] It should be noted that this application is about a micro planetary gear reduction reducer (diameter less than 38mm, aspect ratio of 0-1, power P < 30W) that is paired with a micro motor. The reason for designing the elastic modulus to decrease and the hardness to increase from the input end to the output end is to consider the overall load balance, life balance, and noise level of the planetary gear as a whole (from input to output three stages). First of all, it is important to note that the elastic modulus of the input planetary gear is greater than the elastic modulus of the intermediate planetary gear (the elastic modulus is the largest in the three-stage transmission). This is based on the consideration of reducing noise and large transmission ratio. Those skilled in the art should know that in a micro planetary gear reduction motor, the loss and noise caused by continuous operation are actually common and difficult-to-solve technical problems in this field. The reason why this application chooses a material with the largest elastic modulus and the smallest hardness is based on the factors of the fastest input speed and the smallest torque. Because the input planetary gear reduction is directly connected to the input shaft of the motor, its speed is the output speed of the motor, which is the maximum speed. Under the premise of high-speed operation, high speed means high-frequency vibration. Assuming that the input planetary gear is made of a material with a small elastic modulus and high hardness, such as metal, the high-speed rotating metal planetary gear (generally more than three) will produce a large noise. Therefore, a material with a large elastic modulus and a small hardness, such as TPEE plastic, is used here. The material has a more elastic property. When rotating at high speed, the buffering effect brought by the elastic lock of the material itself can fully reduce the noise generated by its vibration lock.

[0017] It should also be noted that the intermediate planetary gears are made of a material with a lower elastic modulus and greater hardness than the input planetary gears (still plastic, such as nylon) because the intermediate planetary gears actually rotate at a much lower speed than the input planetary gears (the intermediate speed is 1 / 4 to 1 / 6 of the input speed), and the corresponding torque is 4 to 6 times that of the input. Therefore, the intermediate planetary gears experience greater losses than the input planetary gears. Therefore, the material used for the intermediate planetary gears is primarily to meet load requirements, requiring higher hardness and strength. Secondly, to account for noise, metal, which can generate significant noise, cannot be used directly for all three stages of the planetary gears. Therefore, the intermediate planetary gears are made of a plastic with a higher hardness and lower elastic modulus than the input planetary gears. This allows for equivalent load and reduced noise requirements, ensuring that both the input and intermediate gears have the same service life, preventing the overall life of the planetary gear reducer from being shortened due to excessive wear of the intermediate gears.

[0018] Furthermore, the hardness range of the integrally formed intermediate sun gear and the input-end planet carrier is Rockwell M70-M105, and the hardness range of the integrally formed output-end sun gear and the intermediate planet carrier is (HRC15-35).

[0019] Further, the input sun gear is a metal gear made of metal or a plastic gear made of plastic; the input planetary gear is a plastic gear made of plastic, the input planet carrier is a plastic carrier body made of plastic, the intermediate sun gear is a plastic gear made of plastic, the intermediate planetary gear is a plastic gear made of plastic, the intermediate planet carrier is a metal carrier body made of metal, the output sun gear is a metal gear made of metal, the output planetary gear is a metal gear made of metal, and the output planet carrier is a metal carrier body made of metal.

[0020] Further, the input planetary gear is made of thermoplastic polyester elastomer (TPEE plastic), the integrally formed intermediate sun gear and the input planet carrier are made of polyoxymethylene plastic (POM plastic) or nylon plastic (PA plastic), the intermediate planetary gear is made of polyoxymethylene plastic (POM plastic) or nylon plastic (PA plastic), and the metal used in the intermediate planet carrier, the output sun gear, the output planetary gear, and the output planet carrier is copper or steel.

[0021] It should be noted that the selection and matching of materials for the three-stage transmission gear of the present application takes into account many factors, one of which is noise. Those skilled in the art can undoubtedly determine that the noise of the collision and friction between plastics is much smaller than that of the collision and friction between metals. Therefore, when considering the noise factor, the present application does not design both gears between two levels to be made of metal, but uses POM plastic or PA plastic (or similar materials) for the second level and metal (for bearing large torque) for the third level. Therefore, the intermediate and output ends are in contact with each other between plastic and metal, which makes the noise generated by the multi-stage planetary gear reducer of the present application much smaller than that of a pure metal reducer.

[0022] Further, the engagement height of the intermediate sun gear and the intermediate planetary gear is 1-1.2 times the engagement height of the output sun gear and the output planetary gear.

[0023] Further, the engagement height of the input sun gear and the input planetary gear is 0.5-1 times the engagement height of the intermediate sun gear and the intermediate planetary gear.

[0024] It should be noted that the design of the meshing height is also based on the miniaturization of the reduction box, while considering the factors of equal strength, equal life and low noise. From the input end to the middle end to the output end, the speed gradually decreases and the torque gradually increases. Based on this, the torque borne by the input end planetary gear and the input end sun gear is lower than the torque borne by the middle end planetary gear and the middle end sun gear. For example, the transmission ratio between the input end sun gear and the middle sun gear is 6:1, so the torque borne by the middle sun gear is 6 times that of the input sun gear, and the speed of the middle sun gear is 1 / 6 of that of the input sun gear. Assuming that the material selection of the present application is not adopted and the same material is used to manufacture two different levels of sun gears, from the static strength and dynamic strength, if the material and modulus are the same, the height of the middle sun gear should be 6 times that of the input sun gear. Similarly, the height of the output sun gear should also be the corresponding multiple height relationship of the transmission ratio of the middle sun gear, but in fact, whether metal or plastic material, the height of each level of planetary gears or sun gears of the reduction motor or reduction box on the market and known is the same or similar, which obviously does not conform to the logic. The internal reason is obviously not studied in depth. In fact, in addition to the static strength and dynamic strength of each level, there is also a load sharing coefficient, a bending moment of the planet carrier, wear of the planet gear and planet carrier column, replenishment of lubricating grease, stability of noise, and difficulty and cost of manufacturing of parts. It is a very comprehensive problem, and the result of the deduction and test of the present applicant is that if the same material, the same modulus, and the same number of planet gears are used, the height of the planet gears (or sun gears) of each level is preferably increased by 2-3 times with a transmission ratio of 4-6. This is derived from a large amount of test data. The present application balances each comprehensive factor, uses different materials for different levels, and the heights are also different. It is also derived from the above-mentioned research of comprehensive factors. Therefore, one of the important points of the present application is that it fully considers the characteristics of torque increase and speed decrease between the levels of planetary gears, and also considers the length-diameter ratio and noise problems. Therefore, the materials used for the middle planetary gear and the middle sun gear are polyoxymethylene plastic (POM plastic) or nylon plastic (PA plastic), which have greater hardness and smaller elastic modulus than the materials used for the input sun gear and the input planetary gear (TPEE plastic). In short, the torque difference between the levels of planetary gears is designed through the comprehensive design of material selection and meshing height, that is:

[0025] I. The meshing height of the output end sun gear and the output end planetary gear is 1-1.2 times

[0026] II. The materials used for the middle planetary gear and the middle sun gear are polyoxymethylene plastic (POM plastic) or nylon plastic (PA plastic), and the materials used for the input sun gear and the input planetary gear are TPEE plastic

[0027] The combination of one and two makes it possible to achieve low noise and small aspect ratio (0-1).

[0028] It should also be noted that at the output end, the output sun gear and output planetary gears are made of metal, such as steel. In terms of material properties, steel is much harder than POM or PA plastics. Therefore, its torque-bearing capacity is much greater than that of the intermediate sun gear and intermediate planetary gears (steel is more than six times harder than POM or PA plastics). Therefore, based on the consideration of a small aspect ratio, the thickness of the output sun gear and output planetary gears is allowed to be smaller than that of the intermediate sun gear and intermediate planetary gears, and "the meshing height between the input sun gear and the input planetary gears is 0.5 to 1 times the meshing height between the intermediate sun gear and the intermediate planetary gears."

[0029] It's also worth noting that the selection of materials and meshing height for the three stages is based on the technical considerations of achieving equal loads across the three stages, meaning equivalent losses and lifespans for the three planetary gears. Because the input planetary gears are made of the lowest-hardness material, it's important to understand that the lowest hardness also results in the lowest load-bearing capacity (losses are also minimized at the input end, with a Shore D hardness of 52 to 72). Therefore, with a low meshing height, the input planetary gears can still meet load requirements while also minimizing radial dimensions, meeting the overall planetary gear reducer's aspect ratio requirement of 0-1. Assuming the intermediate planetary gears are made of the same material as the input planetary gears, to achieve equivalent loads, the meshing height between the intermediate sun gear and the intermediate planetary gears should be 4 to 6 times that of the input sun gear and the input planetary gears. This design makes it virtually impossible to meet the aspect ratio requirement of less than one. For this reason, the middle-end sun gear is made of a harder material (Rockwell M70-M105). Because hardness acts as a loss balance, the meshing height of the middle end does not need to be 4-6 times that of the input end; instead, it can be only 1-2 times that. This range ensures both load balance between the input and middle ends while also minimizing radial clearance (overall aspect ratio < 1). It's also important to note that the plastic used for the input and output planetary gears actually has a much lower elastic modulus than metal, and consequently, a much lower hardness (steel's hardness is a geometric multiple of nylon plastic, HRC 15-35). Therefore, while the output planetary gears are made of steel, their meshing height can be made even smaller (1-1.2 times the meshing height of the output sun gear and the output planetary gears) than the middle end, while still bearing the maximum load. This allows the output sun gear to still meet the load requirements.

[0030] It should also be noted that the torque increases between the three levels. If the same material is used, for example, POM plastic, and if the strength and life are equal (noise is not considered), the thickness must be increased in proportion to the three levels. If all metal materials are used, according to the same logic, what is a reasonable axial length? In fact, the commercially available NGW planetary reducers do not achieve such a detailed design. This is why the transmission ratio and aspect ratio need to be associated in this application: that is, the further detailed material and height scheme of each layer in this application is the optimal solution for the rationality of the micro reduction motor. If the intermediate layer and input layer are replaced with metal materials instead of the optimal solution of this application, the relationship between the aspect ratio and the transmission ratio can also be met without considering noise conditions. However, no commercially available or publicly known materials clearly propose to meet the associated conditions proposed in this application. The reason is that foreign designs in the industrial field are directly transplanted to the field of micro brushed reduction motors without understanding the comprehensive balance of factors that leads to this result. The present application creatively combines three materials and also specially designs the meshing height difference, so that, in an extremely narrow space, it can meet the requirements of the use of micro planetary gear reduction motors with small aspect ratios (0-1) and large transmission ratios (40-360). This is a creative design that uses systems engineering thinking.

[0031] Preferably, the transmission ratio i of the planetary reduction mechanism satisfies the relationship: 40≤i≤360.

[0032] Preferably, a ratio k of the axial length of the housing to the outer diameter of the housing satisfies the relationship: 0<k<1.

[0033] The planetary gear reduction motor provided by the present invention has a three-stage (input, intermediate, and output) structure. The input planetary gears are made of TPEE elastomer material; the integrally formed intermediate sun gear and the input planetary carrier are made of POM or PA plastic; the intermediate planetary gears are also made of POM or PA plastic; and the integrally formed output sun gear and intermediate planetary carrier are made of copper or steel metal materials. This has the following technical effects:

[0034] 1. Lower assembly difficulty. The intermediate sun gear is integrated with the input planetary carrier, and the output sun gear is integrated with the intermediate planetary carrier. Compared with the traditional assembly method in which the sun gear and the planetary carrier are assembled separately, the micro NGW multi-stage planetary gear reduction motor provided in this application is easier to assemble, has fewer parts, and has less problems such as wear, vibration, and noise due to the connection between parts.

[0035] 2. Lower cost, smaller size, and lighter weight. The material selection in this application is based on the fact that the micro NGW multi-stage planetary gearbox has the characteristics of gradually decreasing speed and gradually increasing torque from input to output. Specifically, at the input end of the reduction gearbox directly connected to the motor, the speed is the fastest and the torque is the smallest. Therefore, TPEE elastic plastic (largest elastic modulus, lowest hardness, suitable for the input end) is suitable for the planetary gear at the input end; the intermediate sun gear and the input end planetary carrier of the integrated design, the intermediate end planetary gear, use PA or POM plastic (Shore hardness of 52ShoreD~72ShoreD, elastic modulus of 300MPa~800MPa). Compared with the input end sun gear, the integrated intermediate sun gear and the input end planetary carrier have a lower speed and a higher torque; and compared with the integrated intermediate sun gear and the input end planetary carrier, the speed of the intermediate end planetary gear is smaller and the torque is larger. Therefore, a material with a higher hardness and a lower elastic modulus (PA or POM plastic, Rockwell hardness of HRM70~105) is used here to meet this requirement. The integrated output sun gear, planetary carrier, and sun gear section withstand the highest torque and lowest speed because they are made of the hardest materials (copper or steel, with a Rockwell hardness of HRC15-35). Compared to traditional methods that use only one material (all metal or all plastic), this application's material selection takes into account various factors, such as cost and material properties, resulting in a high transmission ratio (40≤i≤360), greater durability than all-plastic, smaller size, and lighter weight than all-metal.

[0036] 3. The aspect ratio is smaller. The aspect ratio of the same type of miniature NGW multi-stage planetary gear reduction motor is usually 1.5<k<3.0. The assembly method of this application is adopted (the input planetary carrier of the first stage and the intermediate sun gear of the second stage are integrated into one design, and the intermediate planetary carrier of the second stage and the output sun gear of the third stage are integrated into one design, eliminating the connection redundancy between components), and its aspect ratio k can be 0<k<1. This is actually the applicant's systematic analysis of the transmission relationship between the levels of the multi-stage planetary gears (the sun gear of the upper stage and the planetary carrier of the lower stage are synchronized in transmission), and then creative design (transmission synchronization, so it can be integrated). Therefore, the miniature NGW multi-stage planetary gear designed in this application has a three-stage internal transmission structure, and can still achieve an aspect ratio of: 0<k<1.

[0037] 4. Design of equal lifespan at each level. Since the strength of NGW planetary reduction gearbox increases, the speed decreases, and the noise decreases at each level, how to balance the pros and cons and consider the use of various materials and wear conditions. How to reasonably match it with the motor, considering the power density and torque density of the reduction gearbox, and adapting it to the power density, torque density and lifespan of the existing brushed motor, so as to facilitate the module combination to serve the terminal needs. Gearboxes of the same diameter are preferentially adapted to DC brushed motors of the same diameter, and brushed motors are already mature and relatively standardized products (the commonly used brushed motor aspect ratio is also 1 to 2). The power of the motor is basically proportional to the volume of the motor, and the strength, power, and torque of the reduction gearbox are proportional to the square of the module and the axial length. It is based on this principle that the universality of the aspect ratio and motor matching in this application is achieved.

[0038] 5. Compared with the traditional micro NGW multi-stage planetary reduction motor, the micro NGW multi-stage reduction motor of the present application has a volume reduction of more than 20% (aspect ratio 0 to 1) and a torque and power increase of more than 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0040] Figure 1 1 is a three-dimensional schematic diagram of a planetary gear reduction motor provided by an embodiment of the present invention;

[0041] Figure 2 yes Figure 1 Schematic diagram of the cutaway AA in the figure;

[0042] Figure 3 1 is a left-side plan view schematic diagram of a planetary gear reduction motor provided by an embodiment of the present invention;

[0043] Figure 4 1 is a schematic front cross-sectional view of a planetary gear reduction motor provided by an embodiment of the present invention;

[0044] Figure 5 1 is an exploded schematic diagram of a planetary gear reduction motor provided by an embodiment of the present invention;

[0045] Figure 6 is an exploded schematic diagram of a planetary reduction mechanism provided by an embodiment of the present invention;

[0046] Figure 7 This is a schematic diagram of the shell provided by the embodiment of the present invention. Figure 1 ;

[0047] Figure 8 This is a schematic diagram of the shell provided by the embodiment of the present invention. Figure 2 ;

[0048] Figure 9 It is an exploded schematic diagram of the output shaft, guide sleeve and housing provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0050] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0051] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element.

[0052] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0053] like Figure 1-9As shown, a planetary gear reduction motor provided by an embodiment of the present invention includes a motor 100 and a planetary reducer 200 mounted at one end of the motor 100. The planetary reducer 200 includes a housing 210, a planetary reduction mechanism 220 disposed within the housing 210, and an output shaft 230, one end of which extends outside the housing 210 and the other end of which passes through the housing 210 and is connected to one end of the planetary reduction mechanism 220. The motor 100 includes a drive shaft 110, one end of which passes through the housing 210 and is connected to the other end of the planetary reduction mechanism 220. The transmission ratio i of the planetary reduction mechanism 220 satisfies the relationship: 40≤i≤360, and the ratio k of the axial length L of the housing 210 to the outer diameter D of the housing 210 satisfies the relationship: 0<k<1. I is the transmission ratio of the planetary reducer 200, and k is the aspect ratio of the housing 210 or the aspect ratio of the planetary reducer 200. The power output by the motor 100 is reduced by the planetary reduction mechanism 220 and then output to the actuator via the output shaft 230. In the planetary gear reduction motor provided in an embodiment of the present invention, the transmission ratio i of the planetary reduction mechanism 220 is between 40 and 360, and the aspect ratio k of the planetary reducer 200 is less than 1. In this way, it not only meets the design requirements of the planetary gear reduction motor with a large transmission ratio, but also meets the installation requirements of certain applications requiring a small aspect ratio.

[0054] Preferably, 45≤i≤360; and / or, 0<k≤0.95. As a preferred implementation of this embodiment, 45≤i≤360; and 0<k≤0.95.

[0055] More preferably, 45≤i≤300; and / or, 0.4≤k≤0.9, so that the transmission ratio and aspect ratio of the planetary reducer 200 can be optimized to an excellent degree.

[0056] Preferably, refer to Figure 2 and Figure 4 As shown, the planetary reduction mechanism 220 includes an input sun gear 221 mounted on the drive shaft 110, an input planetary assembly 222 drivingly connected at one end to the input sun gear 221, an output planetary assembly 223 drivingly connected at one end to the output shaft 230, and an intermediate planetary assembly 224 drivingly connected between the input planetary assembly 222 and the output planetary assembly 223. The planetary reduction mechanism 220 in this embodiment is a three-stage reduction transmission mechanism, wherein the transmission between the input sun gear 221 and the input planetary assembly 222 constitutes a first-stage reduction transmission, the transmission between the input planetary assembly 222 and the intermediate planetary assembly 224 constitutes a second-stage reduction transmission, and the transmission between the intermediate planetary assembly 224 and the output planetary assembly 223 constitutes a third-stage transmission.

[0057] Preferably, refer to Figure 2 、 Figure 4 and Figure 6As shown, the input-end planetary assembly 222 includes a plurality of input-end planetary gears 2221 surrounding the periphery of the input-end sun gear 221 and meshing with the input-end sun gear 221, an input-end planetary carrier 2222 connected to the input-end planetary gears 2221 at one end, and an intermediate sun gear 2223 connected to the input-end planetary carrier 2222; the intermediate planetary assembly 224 includes a plurality of intermediate planetary gears 2241 surrounding the periphery of the intermediate sun gear 2223 and meshing with the intermediate sun gear 2223, an intermediate planetary carrier 2242 connected to the intermediate planetary gears 2241 at one end, and The output sun gear 2243 is connected to the intermediate planetary carrier 2242. The output planetary assembly 223 includes a plurality of output planetary gears 2231 surrounding the outer circumference of the output sun gear 2243 and meshing with the output sun gear 2243, and an output planetary carrier 2232 connected at one end to the output planetary gears 2231 and at the other end to the drive shaft 110. An inner ring gear 2113 is provided on the inner sidewall of the housing 210, with which each of the input planetary gears 2221, each of the intermediate planetary gears 2241, and each of the output planetary gears 2231 meshes. The provision of the inner ring gear 2113 on the inner sidewall of the housing 210 for meshing with each of the input planetary gears 2221, each of the intermediate planetary gears 2241, and each of the output planetary gears 2231 helps improve the operational stability and reliability of the planetary reducer 200.

[0058] Preferably, the input end sun gear 221 is a metal gear made of metal or a plastic gear made of plastic; the input end planetary gear 2221 is a plastic gear made of plastic; the input end planetary carrier 2222 is a plastic frame made of plastic; the intermediate sun gear 2223 is a plastic gear made of plastic; the intermediate planetary gear 2241 is a plastic gear made of plastic; the intermediate planetary carrier 2242 is a metal frame made of metal; the output end sun gear 2243 is a metal gear made of metal; the output end planetary gear 2231 is a metal gear made of metal; and the output end planetary carrier 2232 is a metal frame made of metal. Here, by optimizing the material design of each component in the planetary reduction mechanism 220, an optimized combination of metal components and plastic components is achieved. This is beneficial for ensuring the strength and service life of the reduction transmission structure at each level of the planetary reduction mechanism 220, and for reducing the vibration, noise, weight and size of the planetary reducer 200. As a result, when the transmission ratio i of the planetary reduction mechanism 220 is between 40 and 360, the aspect ratio of the planetary reducer 200 can be designed to be less than 0.9, which is an excellent optimization effect.

[0059] Preferably, the intermediate sun gear 2223 and the input-end planetary carrier 2222 are integrally formed, and the intermediate sun gear 2223 and the input-end planetary carrier 2222 are made of the same material, and the subsequent assembly process of the intermediate sun gear 2223 and the input-end planetary carrier 2222 is eliminated, thereby improving the connection stability between the intermediate sun gear 2223 and the input-end planetary carrier 2222, thereby helping to reduce the vibration and noise generated during the operation of the planetary reduction mechanism 220.

[0060] Preferably, the output end sun gear 2243 and the intermediate planetary carrier 2242 are integrally formed, and the output end sun gear 2243 and the intermediate planetary carrier 2242 are made of the same material, and the subsequent assembly process of the output end sun gear 2243 and the intermediate planetary carrier 2242 is eliminated, thereby improving the connection stability between the output end sun gear 2243 and the intermediate planetary carrier 2242, thereby helping to reduce the vibration and noise generated during the operation of the planetary reduction mechanism 220.

[0061] Preferably, the hardness of the input planetary gears 2221 is less than that of the intermediate planetary gears 2241, and the elastic modulus of the input planetary gears 2221 is greater than that of the intermediate planetary gears 2241. The input planetary gears 2221 are made of plastic with a lower hardness and a higher elastic modulus, which can improve the vibration and noise reduction effects of the input planetary gears 2221. Meanwhile, the intermediate planetary gears 2241 are made of plastic with a higher hardness and a lower elastic modulus, which can improve the strength and wear resistance of the intermediate planetary gears 2241, thereby extending the service life of the intermediate planetary gears 2241.

[0062] As a preferred implementation scheme of this embodiment, the number of input-end planetary gears 2221, intermediate planetary gears 2241 and output-end planetary gears 2231 is three. Of course, in specific applications, the number of input-end planetary gears 2221, intermediate planetary gears 2241 and output-end planetary gears 2231 is not limited to this, and can also be two or more than four.

[0063] Preferably, the meshing height between the intermediate sun gear 2223 and the intermediate planetary gears 2241 is 1 to 1.2 times the meshing height between the output sun gear 2243 and the output planetary gears 2231. This helps ensure transmission stability and reliability while also reducing the overall axial length of the planetary reducer 200. The meshing height between the intermediate sun gear 2223 and the intermediate planetary gears 2241 is specifically the projected dimension of the meshing portion of the intermediate sun gear 2223 and the intermediate planetary gears 2241 in the axial direction of the planetary reducer 200. The meshing height between the output sun gear 2243 and the output planetary gears 2231 is specifically the projected dimension of the meshing portion of the output sun gear 2243 and the output planetary gears 2231 in the axial direction of the planetary reducer 200.

[0064] Preferably, the meshing height between the input sun gear 221 and the input planetary gears 2221 is 0.5 to 1 times the meshing height between the intermediate sun gear 2223 and the intermediate planetary gears 2241. This helps ensure stable and reliable transmission while also reducing the overall axial length of the planetary reducer 200. The meshing height between the input sun gear 221 and the input planetary gears 2221 is specifically the projected dimension of the meshing portion of the input sun gear 221 and the input planetary gears 2221 in the axial direction of the planetary reducer 200.

[0065] Preferably, the number of teeth of the input end sun gear 221, the number of teeth of the intermediate sun gear 2223, and the number of teeth of the output end sun gear 2243 are all the same. For ease of description, the number of teeth of the input end sun gear 221, the number of teeth of the intermediate sun gear 2223, and the number of teeth of the output end sun gear 2243 are all defined as z1, and the number of teeth of the inner ring gear 2113 is defined as z2, then i = (z2 / z1+1) 3 .

[0066] As a preferred embodiment of this embodiment, the number of teeth z2 of the inner ring gear 2113 is 48, the number of teeth of the input end sun gear 221, the number of teeth of the intermediate sun gear 2223, and the number of teeth z1 of the output end sun gear 2243 are all 9, and according to the formula i = (z2 / z1+1) 3 Calculation shows that i≈45. Of course, the values ​​of z1 and z2 are not limited to this. In specific applications, different transmission ratios i can be obtained by adjusting different combinations of z1 and z2.

[0067] Preferably, refer to Figure 6 As shown, the input planetary carrier 2222 includes an input baseplate 201 and a plurality of circumferentially spaced input positioning posts 202. The input positioning posts 202 and the intermediate sun gear 2223 are respectively projecting from either side of the input baseplate 201, and each input planetary gear 2221 is sleeved onto each input positioning post 202. The input positioning posts 202 radially limit the input planetary gears 2221, thereby improving the operational stability and reliability of the input planetary gears 2221. The axial ends of the input planetary gears 2221 respectively abut against the input planetary carrier 2222 and the housing 210 at the ends proximal to the motor 100, thereby axially limiting the input planetary gears 2221.

[0068] Preferably, refer to Figure 6As shown, the intermediate carrier 2242 comprises an intermediate base plate 203 and a plurality of intermediate positioning columns 204 distributed along the circumference, the intermediate positioning columns 204 and the output sun gear 2243 are respectively protruded on both sides of the intermediate base plate 203, and each intermediate planetary gear 2241 is sleeved on each intermediate positioning column 204. The intermediate positioning column 204 can play a role of radially limiting the intermediate planetary gear 2241, thereby facilitating to improve the stable reliability of the operation of the intermediate planetary gear 2241. The axially opposite ends of the intermediate planetary gear 2241 are respectively abutted on the intermediate carrier 2242 and the output carrier 2232, thereby playing a role of axially limiting the intermediate planetary gear 2241.

[0069] Preferably, referring to Figure 6 As shown, the output carrier 2232 comprises an output base plate 205 and a plurality of input positioning columns 202 distributed along the circumference, each output positioning column 206 is protruded on one side of the input base plate 201, and each output planetary gear 2231 is sleeved on each output positioning column 206. The output positioning column 206 can play a role of radially limiting the output planetary gear 2231, thereby facilitating to improve the stable reliability of the operation of the output planetary gear 2231. The axially opposite ends of the output planetary gear 2231 are respectively abutted on the output carrier 2232 and the end of the housing 210 away from the motor 100, thereby playing a role of axially limiting the output planetary gear 2231.

[0070] Preferably, referring to Figure 2 、 Figure 4 and Figure 7-9 As shown, the housing 210 comprises a main shell 211 and an end cover 212, the main shell 211 comprises a hollow cylinder portion 2111 and a cover plate portion 2112 provided at one end of the hollow cylinder portion 2111, the end cover 212 is detachably installed at the other end of the hollow cylinder portion 2111, and the inner ring gear 2113 is provided on the inner side wall of the hollow cylinder portion 2111. The planetary reduction mechanism 220 is installed in the inner cavity formed by the cover plate portion 2112, the hollow cylinder portion 2111 and the end cover 212. The drive shaft 110 passes through the inner cavity from the end cover 212 and is connected to one end of the planetary reduction mechanism 220, and the output shaft 230 passes through the inner cavity from the cover plate portion 2112 and is connected to the other end of the planetary reduction mechanism 220. In this embodiment, the outer side of the housing 210 is in a cylindrical shape.

[0071] Preferably, referring to Figure 2 、 Figure 4 and Figure 7-9As shown, the outer wall of the end portion of the output shaft 230 connected to the output end planetary carrier 2232 is provided with a knurled pattern 231 formed by a knurling process. The output shaft 230 cooperates with the hole on the output end planetary carrier 2232 through the knurled pattern 231, which helps prevent the output shaft 230 and the output end planetary carrier 2232 from rotating with each other, thereby helping to improve the reliability of the output end planetary carrier 2232 driving the output shaft 230 to rotate.

[0072] Preferably, refer to Figure 2 、 Figure 4 and Figure 7-9 As shown, the cover portion 2112 is provided with a mounting hole 2116 for the output shaft 230 to pass through, and a guide sleeve 240 is provided between the output shaft 230 and the mounting hole 2116. The provision of the guide sleeve 240 can prevent the output shaft 230 from directly contacting the cover portion 2112, thereby helping to increase the service life of the housing 210.

[0073] Preferably, the hollow cylinder 2111 and the end cover 212 are detachably connected by a snap connection, so that the assembly and disassembly of the main shell 211 and the end cover 212 can be completed by hand without the aid of any auxiliary tools, and the assembly and disassembly operations are very simple and convenient.

[0074] Preferably, refer to Figure 2 、 Figure 4 and Figure 7-9 As shown, the sidewall of the end of the hollow cylindrical portion 2111 away from the cover portion 2112 is provided with a plurality of positioning notches 2114 and a plurality of buckle holes 2115. The positioning notches 2114 and the buckle holes 2115 are alternately distributed along the circumference of the hollow cylindrical portion 2111. The end cover 212 is provided with a plurality of positioning protrusions 2121 for respectively engaging with the positioning notches 2114 and a plurality of buckles 2122 for respectively engaging with the buckle holes 2115. During installation, the positioning protrusions 2121 are engaged in the positioning notches 2114, and the buckles 2122 are engaged in the buckle holes 2115, thereby achieving a buckle connection between the main housing 211 and the end cover 212.

[0075] Preferably, the power of the motor 100 is 30W or less.

[0076] In the embodiment of the present invention, the working principle of the planetary gear reduction motor is as follows: the motor 100 is started, the drive shaft 110 drives the input end sun gear 221 to rotate, the input end sun gear 221 drives the input end planetary gear 2221 to rotate, the input end planetary gear 2221 drives the input end planetary carrier 2222 and the intermediate sun gear 2223 to rotate, the intermediate sun gear 2223 drives the intermediate planetary gear 2241 to rotate, the intermediate planetary gear 2241 drives the intermediate planetary carrier 2242 and the output end sun gear 2243 to rotate, the output end sun gear 2243 drives the output end planetary gear 2231 to rotate, the output end planetary gear 2231 drives the output end planetary carrier 2232 to rotate, and the output end planetary carrier 2232 drives the output shaft 230 to rotate, thereby realizing the transmission output of the power of the planetary gear reduction motor.

[0077] In the planetary reduction mechanism 220 of the embodiment of the present invention, the output end transmission part is made entirely of metal parts (i.e., the output end sun gear 2243, the output end planetary carrier 2232, and the output end planetary gear 2231 are all made of metal), the intermediate transmission part is made of a combination of a metal planetary carrier, a plastic planetary gear, and a plastic sun gear (i.e., the intermediate planetary carrier 2242 is made of metal, the intermediate planetary gear 2241 is made of plastic, and the intermediate sun gear 2223 is made of plastic), and the input end transmission part is made of a combination of a plastic planetary carrier, a plastic planetary gear, and a metal sun gear or a plastic sun gear (i.e., the input end planetary carrier 222 2 is made of plastic, the input-end planetary gear 2221 is made of plastic, and the input-end sun gear 221 is made of metal or plastic). In this way, the input-end transmission part can achieve good vibration reduction, noise reduction, and weight reduction effects. While ensuring the strength, the intermediate transmission part can further achieve the effects of vibration reduction, noise reduction, and weight reduction. The output-end transmission part can better meet the strength and impact resistance requirements of the components, thereby ensuring the vibration reduction and noise reduction effects of the planetary reducer 200, and ensuring the strength and service life of the planetary reducer 200, while also effectively reducing the aspect ratio and weight of the planetary reducer 200.

[0078] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A micro NGW multi-stage planetary gear reduction motor, comprising a motor and a planetary reducer mounted on one end of the motor, characterized in that: The motor is a brushed DC motor. The ratio t of the motor's axial length to its diameter satisfies the relationship: 1≤t≤2. The ratio y of the diameter of the reduction motor and the reduction box satisfies the relationship: 0.95<y<1.

05. The planetary reducer includes a housing, a planetary reduction mechanism disposed in the housing, and an output shaft with one end extending outside the housing and the other end passing through the housing and connected to one end of the planetary reduction mechanism. The motor has a drive shaft with one end passing through the housing and connected to the other end of the planetary reduction mechanism. The transmission ratio i of the planetary reduction mechanism satisfies the relationship: 40≤i≤360. The ratio k of the axial length of the housing to the outer diameter of the housing satisfies the relationship: 0<k<1.

2. The micro NGW multi-stage planetary gear reduction motor according to claim 1 comprises an input end sun gear, an input end planet gear, an input end planet carrier, an intermediate sun gear, an intermediate planet gear, an intermediate planet carrier, an output end sun gear, an output end planet gear, an output end planet carrier, and an inner ring gear on the inner side wall, characterized in that: The intermediate sun gear is integrally formed with the input end planet carrier; and / or, The output end sun gear and the intermediate planet carrier are formed in one piece.

3. The micro NGW multi-stage planetary gear reduction motor according to claim 2, characterized in that: The hardness of the input-end planetary gear is smaller than that of the intermediate planetary gear, and the elastic modulus of the input-end planetary gear is larger than that of the intermediate planetary gear.

4. The micro NGW multi-stage planetary gear reduction motor according to claim 2, characterized in that: The meshing height between the intermediate sun gear and the intermediate planetary gears is 1 to 1.2 times the meshing height between the output end sun gear and the output end planetary gears; and / or, The meshing height between the input-end sun gear and the input-end planetary gears is 0.5 to 1 times the meshing height between the intermediate sun gear and the intermediate planetary gears.

5. The micro NGW multi-stage planetary gear reduction motor according to claim 3, characterized in that: The hardness of the input end planetary gear is 52ShoreD to 72ShoreD in Shore hardness, and the elastic modulus is 300MPa to 800MPa.

6. The micro NGW multi-stage planetary gear reduction motor according to claim 3, characterized in that: The hardness range of the integrally formed intermediate sun gear and the input-end planet carrier is Rockwell M70-M105, and the hardness range of the integrally formed output-end sun gear and the intermediate planet carrier is (HRC15-35).

7. The micro NGW multi-stage planetary gear reduction motor according to any one of claims 3, 5 and 6, characterized in that: The input end sun gear is a metal gear made of metal or a plastic gear made of plastic; The planetary gear at the input end is a plastic gear made of plastic; The input end planetary carrier is a plastic frame made of plastic; The intermediate sun gear is a plastic gear made of plastic; The intermediate planetary gear is a plastic gear made of plastic; The intermediate planet carrier is a metal frame made of metal; The output end sun gear is a metal gear made of metal; The output end planetary gear is a metal gear made of metal; The output end planetary carrier is a metal frame made of metal.

8. The micro NGW multi-stage planetary gear reduction motor according to any one of claims 7, characterized in that: The input end planetary gear is made of thermoplastic polyester elastomer (TPEE plastic); The integrally formed intermediate sun gear and the input end planetary carrier are made of polyoxymethylene plastic (POM plastic) or nylon plastic (PA plastic); The intermediate end planetary gear is made of polyoxymethylene plastic (POM plastic) or nylon plastic (PA plastic); The metal used for the intermediate planet carrier, the output end sun gear, the output end planet gear, and the output end planet carrier is copper.

9. The micro NGW multi-stage planetary gear reduction motor according to claim 1, characterized in that: 45≤i≤360; and / or, 0<k≤0.

95.

10. The micro NGW multi-stage planetary gear reduction motor according to claim 9, characterized in that: 45≤i≤300; and / or, 0.4≤k≤0.9.

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