Rotary joint module and method for controlling the air gap between the stator and the rotor

Abstract

This application discloses a rotary joint module and a method for controlling the air gap between the stator and rotor, relating to the field of motor technology. The rotary joint module includes: a reducer having an input shaft; an axial flux motor including a motor housing, a rotor shaft, a rotor assembly, a first stator assembly, and a second stator assembly; the motor housing is detachably fixedly connected to the reducer; the rotor shaft is rotatably connected within the motor housing and its axial movement is restricted by the motor housing, while one end of the rotor shaft is connected to the input shaft; the rotor assembly is sleeved on the rotor shaft and rotates synchronously with it; the first stator assembly and the second stator assembly are fixedly disposed within the motor housing and arranged on both sides of the rotor assembly, forming two axial air gaps respectively; the axial flux motor also includes an axial adjustment component, which is fixedly installed on the rotor shaft and abuts against the rotor assembly; the axial adjustment component has a preset thickness for limiting the two axial air gaps to a target value.

Description

Technical Field

[0001] This application relates to the field of motor technology, and in particular discloses a rotary joint module and a method for controlling the air gap between the stator and rotor. Background Technology

[0002] Under the driving requirements of high compactness and high dynamic response of humanoid robots, traditional radial flux motors are limited by low power density and axial dimension redundancy, making it difficult to meet the stringent integration requirements of rotary joint modules. Axial flux motors, with their advantages of short axial dimension, high torque density and excellent heat dissipation performance, can significantly improve the power density and dexterity of joints, and therefore have become an essential technical path for driving the rotary joints of high-performance humanoid robots.

[0003] To achieve axial compactness, existing axial flux motor rotary joint modules integrate core components such as the motor, reducer, encoder, and driver into a single unit. This typically employs a coaxial structure where the reducer input shaft and motor rotor shaft are coaxial. However, this approach has several drawbacks: First, the air gap between the motor stator and rotor requires high precision. In a coaxial structure, the air gap is affected by the reducer assembly dimension chain and the axial movement of the reducer input shaft. This places high demands on component machining tolerances and assembly processes, resulting in low mass production efficiency. Second, during operation, the reducer input shaft experiences axial movement exceeding ±0.1mm due to bearing clearance and assembly gaps. Since the reducer shaft and motor rotor shaft are coaxial, this movement is directly transmitted to the motor rotor, causing changes in the axial air gap between the stator and rotor, thus affecting the motor's electromagnetic performance and output stability. Industry standards require that the air gap variation not exceed ±10% of the average air gap. Simulation results show... Figures 1 to 3 As shown, when the air gap deviation at both ends reaches or exceeds ±0.05mm, magnetic field asymmetry will occur, the excitation current will increase abnormally, the overall efficiency of the motor can decrease by 5%~15%, and the torque fluctuation can rise to more than 3 times that of the uniform air gap state. At the same time, the non-uniform air gap will generate unbalanced axial magnetic pull, which will significantly increase the additional load on the bearing and accelerate the wear rate by 2~3 times. In severe cases, it will cause rotor rubbing failure. In addition, with the coaxial structure of the reducer and the motor rotor, if any component of the reducer or the motor is damaged, the entire joint module must be disassembled, and the stator and rotor air gaps need to be readjusted after reassembly, resulting in high maintenance costs. Therefore, improvements are needed. Summary of the Invention

[0004] The purpose of this application is to provide a rotary joint module.

[0005] Another objective of this application is to provide a method for controlling the air gap between the stator and rotor.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: a rotary joint module, comprising: a reducer having an input shaft; an axial flux motor including a motor housing, a rotor shaft, a rotor assembly, a first stator assembly, and a second stator assembly; the motor housing being detachably fixedly connected to the reducer; the rotor shaft being rotatably connected within the motor housing and having its axial movement restricted by the motor housing, with one end connected to the input shaft; the rotor assembly being sleeved on the rotor shaft and rotating synchronously therewith; the first stator assembly and the second stator assembly being fixedly disposed within the motor housing and arranged on both sides of the rotor assembly, forming two axial air gaps respectively; the axial flux motor also includes an axial adjustment component, which is fixedly installed on the rotor shaft and abuts against the rotor assembly; the axial adjustment component has a preset thickness for limiting the two axial air gaps to a target value.

[0007] As a preferred embodiment, the rotor shaft has a shoulder, and the axial adjustment member is located between the shoulder and the rotor assembly, with one side abutting against the shoulder and the other side abutting against the rotor assembly, thereby fixing the axial position of the rotor assembly on the rotor shaft.

[0008] As a preferred embodiment, the rotor shaft further comprises a first groove and a second groove, the first groove and the second groove being located on opposite axial sides of the shoulder, the first groove containing a first retaining ring and the second groove containing a second retaining ring; the rotor shaft is also fitted with a first bearing and a second bearing, the first bearing and the second bearing being located on opposite axial sides of the rotor assembly, one side of the inner ring of the first bearing abutting against the first retaining ring and the other side abutting against the shoulder, one side of the inner ring of the second bearing abutting against the second retaining ring and the other side abutting against the rotor assembly; the first retaining ring and the second retaining ring axially confine the first bearing, the second bearing and the rotor assembly on the rotor shaft.

[0009] As a preferred embodiment, the motor housing includes a motor housing and a motor end cover, the motor housing and the motor end cover being detachably fixedly connected, the first stator assembly being fixedly mounted on the motor housing, and the second stator assembly being fixedly mounted on the motor end cover; the outer ring of the first bearing abuts against the motor housing, the outer ring of the second bearing abuts against the motor end cover, and the rotor shaft is rotatably connected within the motor housing via the first bearing and the second bearing, and its axial movement is restricted by the motor housing.

[0010] Further preferably, the motor housing has a first mounting surface and an end face, and the motor end cover has a third mounting surface and a fourth mounting surface. When the motor housing and the motor end cover are fitted together, the end face abuts against the fourth mounting surface. When the first stator assembly is assembled, its side facing away from the rotor assembly abuts against the first mounting surface. When the second stator assembly is assembled, its side facing away from the rotor assembly abuts against the third mounting surface. The motor housing also has a second mounting surface, and the motor end cover also has a positioning surface. The outer ring of the first bearing abuts against the second mounting surface on the side facing the first retaining ring, and the outer ring of the second bearing abuts against the positioning surface on the side facing the second retaining ring. After the axial positions of the first stator assembly, the rotor assembly, and the second stator assembly are fixed, the target value is that the axial size deviation of the two axial air gaps is less than 0.05 mm.

[0011] As a preferred embodiment, the two axial air gaps are respectively a first axial air gap and a second axial air gap. The rotor assembly includes a rotor hub and a plurality of permanent magnets symmetrically arranged on both sides of the rotor hub. The permanent magnets on the rotor hub facing the first stator assembly form the first axial air gap with the first stator assembly, and the permanent magnets on the rotor hub facing the second stator assembly form the second axial air gap with the second stator assembly.

[0012] As a preferred embodiment, the preset thickness of the axial adjustment member is determined based on the dimensions of the motor housing, the rotor shaft, the rotor assembly, the first stator assembly, the second stator assembly, and the first bearing, and satisfies the following: S = δ1 + F1 - G2 - E1 - Z2 - L2, Wherein, S is the preset thickness of the axial adjustment component, δ1 is the axial dimension of the first axial air gap, F1 is the axial thickness of the first stator assembly, G2 is the axial distance between one end face of the rotor hub and the same end face of the permanent magnet on the same side, E1 is the axial thickness of the first bearing, Z2 is the axial thickness of the shoulder, and L2 is the axial distance between the first mounting surface and the second mounting surface. The axial dimension δ1 of the first axial air gap satisfies: δ1=0.5×(L1-F1-G1-F2-D2), Wherein, L1 is the axial distance between the first mounting surface and the end face, G1 is the axial distance between the outer surfaces of the permanent magnets on both sides, F2 is the axial thickness of the second stator assembly, and D2 is the axial distance between the third mounting surface and the fourth mounting surface.

[0013] As a preferred embodiment, the reducer further includes a reducer housing and an output flange. The reducer housing is detachably and fixedly connected to the motor housing. The input shaft is rotatably mounted inside the reducer housing. The output flange is sleeved on one end of the input shaft. A low-speed shaft is also fixedly connected to the output flange, and the low-speed shaft passes through the input shaft and the rotor shaft in sequence before connecting to the encoder assembly. A driver cover is also detachably and fixedly connected to the end of the axial flux motor facing away from the reducer. A driver is disposed inside the driver cover and is mounted on the motor end cover. A bushing is fixedly disposed on the driver cover and is connected to the end of the low-speed shaft.

[0014] As a preferred embodiment, an inner support frame is fixedly provided at the end of the low-speed shaft, and an outer support frame is fixedly provided at the end of the rotor shaft away from the reducer. The encoder assembly includes an encoder circuit board, an outer induction ring, and an inner induction ring. The outer induction ring is connected to the outer support frame and rotates synchronously with the rotor shaft, and is used to collect the speed and number of revolutions of the axial flux motor as input signals. The inner induction ring is connected to the inner support frame and rotates synchronously with the low-speed shaft, and is used to collect the speed and number of revolutions of the axial flux motor as output signals. A read head is fixed on the encoder circuit board, and the read head is arranged opposite to the outer induction ring and the inner induction ring, and is used to read the signals of the outer induction ring and the inner induction ring.

[0015] A stator-rotor air gap control method is used for the axial flux motor in the rotary joint module. The control method includes the following steps: Step A: Obtain the dimensional values ​​of each component inside the axial flux motor; Step B: Based solely on the obtained dimensional values ​​of the internal components of the axial flux motor, calculate the target value of the axial air gap between the stator assembly and the rotor assembly, and calculate the preset thickness value of the axial adjustment component. Step C: Select an axial adjustment component with the preset thickness value and install it on the rotor shaft to fix the axial position of the rotor assembly, thereby adjusting the axial air gap and limiting it to the target value.

[0016] As a preferred embodiment, step B, calculating the target value of the axial air gap and the preset thickness value of the axial adjustment component, includes the following steps: Step a: Calculate the target values ​​of the first axial air gap δ1 and the second axial air gap δ2 based on the dimensions of the motor housing, motor end cover, rotor assembly, first stator assembly, and second stator assembly. δ1=δ2= 0.5×(L1-F1-G1-F2-D2), Where L1 is the axial distance between the first mounting surface and the end face, G1 is the axial distance between the outer surfaces of the two permanent magnet bodies, F2 is the axial thickness of the second stator assembly, and D2 is the axial distance between the third mounting surface and the fourth mounting surface. Step b: Calculate the distance L0 between the first mounting surface and the opposite surface of the rotor hub. L0 = δ1 + F1 - G2, Where F1 is the axial thickness of the first stator assembly, and G2 is the axial distance between one end face of the rotor hub and the same end face of the permanent magnet on the same side. Step c: Calculate the preset thickness S of the axial adjustment component: S= L0-E1-Z2-L2=δ1+F1-G2-E1-Z2-L2, Where E1 is the axial thickness of the first bearing, Z2 is the axial thickness of the shoulder, and L2 is the axial distance between the first mounting surface and the second mounting surface. After step B, calculate the thickness H1 of the first retaining ring and the thickness H2 of the second retaining ring respectively: H1=Z3-E1, H2=Z1-Z3-Z2-G3-E2-S, Where Z3 is the distance between the outer wall of the first groove and the inner wall of the shoulder, Z1 is the axial distance between the outer wall of the first groove and the outer wall of the second groove, G3 is the axial thickness of the rotor hub, and E2 is the axial thickness of the second bearing.

[0017] Compared with the prior art, the beneficial effects of this application are as follows: (1) This application restricts the axial movement of the rotor assembly by fixing the axial adjustment component on the rotor shaft and abutting against the rotor assembly. The axial position of the rotor assembly is independently limited by the preset thickness of the axial adjustment component, rather than determined by the axial position of the reducer input shaft. Since the axial movement of the rotor shaft is restricted by the motor housing, the axial movement of the reducer input shaft cannot be transmitted to the rotor shaft. The axial air gap between the motor stator and rotor remains constant, avoiding problems such as decreased electromagnetic performance, increased torque fluctuation, unbalanced axial magnetic pull, and aggravated bearing wear caused by changes in the axial air gap.

[0018] (2) In this application, the axial flux motor is an independent sub-component. Its axial air gap adjustment depends only on the dimensional chain of the internal parts of the motor. The assembly dimensional chain of the reducer will not be introduced into the calculation of the axial air gap adjustment. The axial flux motor can independently complete the axial air gap pre-adjustment on the assembly line and then be assembled with the reducer as a whole. This greatly shortens the dimensional chain during the assembly of the whole machine, reduces the requirements for the machining tolerance and assembly process of the reducer parts, and is conducive to mass production.

[0019] (3) Since the axial air gap of the axial flux motor is independently limited by its internal axial adjustment component, it is not related to the size and assembly state of the reducer. There is no one-to-one assembly relationship between the axial flux motor and the reducer due to the coupling of the size chain. When any component of the reducer or the axial flux motor is damaged, the corresponding component can be directly disassembled and replaced. After replacement, there is no need to readjust the axial air gap between the motor stator and rotor, which greatly reduces the maintenance cost and maintenance difficulty.

[0020] (4) The axial air gap control method of this application can complete the accurate calculation and adjustment of the axial air gap based only on the size values ​​of each part inside the axial flux motor. It does not need to rely on the assembly dimension chain of external components such as reducers. This allows the axial flux motor to be pre-adjusted as an independent sub-component before being assembled with external components. This avoids the influence of the assembly dimension chain of external components and the axial movement of external components on the accuracy of the axial air gap, effectively reduces the assembly difficulty of the whole machine, and improves the maintenance performance of the axial flux motor and external components. Attached Figure Description

[0021] Figure 1 This is a simulation result of the cogging torque of the rotor assembly under no offset condition.

[0022] Figure 2 This is a simulation result of the cogging torque when the rotor assembly is offset by 0.05mm.

[0023] Figure 3 Simulation results of the axial magnetic pull of the stator assembly at different offset distances of the rotor assembly.

[0024] Figure 4 This is a three-dimensional structural diagram of the present invention.

[0025] Figure 5 This is an exploded view of the three-dimensional structure of the present invention.

[0026] Figure 6 This is a three-dimensional structural cross-sectional view of the present invention.

[0027] Figure 7 This is a cross-sectional view of the present invention.

[0028] Figure 8 This is a three-dimensional structural diagram of the axial flux motor of the present invention.

[0029] Figure 9 This is an exploded view of the three-dimensional structure of the axial flux motor of the present invention.

[0030] Figure 10 This is a cross-sectional view of the axial flux motor of the present invention.

[0031] Figure 11 This is a partial enlarged cross-sectional view of the axial flux motor of the present invention.

[0032] Figure 12 This is a cross-sectional view of the rotor assembly and rotor shaft in the engagement state of the present invention.

[0033] Figure 13 This is a cross-sectional view of the rotor assembly of the present invention.

[0034] Figure 14 This is a cross-sectional view of the rotor shaft of the present invention.

[0035] Figure 15 This is a cross-sectional view of the axial adjustment component of the present invention.

[0036] Figure 16 This is a cross-sectional view of the motor housing of the present invention.

[0037] Figure 17 This is a cross-sectional view of the motor end cover of the present invention.

[0038] In the diagram: 1. Reducer; 11. Reducer housing; 12. Output flange; 13. Input shaft; 2. Axial flux motor; 201. Motor housing; 2011. First mounting surface; 2012. End face; 2013. Second mounting surface; 202. First stator assembly; 203. Rotor assembly; 2031. Permanent magnet; 2032. Rotor hub; 204. Second stator assembly; 205. Motor end cover; 2051. Third mounting surface; 2052. Positioning surface; 20 53. Fourth mounting surface; 206. Rotor shaft; 2061. First groove; 2062. Second groove; 2063. Shoulder; 207. First retaining ring; 208. First bearing; 209. Axial adjustment component; 210. Second bearing; 211. Second retaining ring; 3. Driver; 4. Driver cover; 5. Outer support frame; 6. Encoder assembly; 61. Encoder circuit board; 62. Outer sensing ring; 63. Inner sensing ring; 7. Inner support frame; 8. Bushing; 9. Low-speed shaft. Detailed Implementation

[0039] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0040] In the description of this application, it should be noted that the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., which indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of this application.

[0041] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0042] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0043] A preferred embodiment of this application, such as Figures 4 to 17 As shown, a rotary joint module includes: Reducer 1 has an input shaft 13.

[0044] The axial flux motor 2 includes a motor housing, a rotor shaft 206, a rotor assembly 203, a first stator assembly 202, and a second stator assembly 204. The motor housing is detachably fixedly connected to the reducer 1. The rotor shaft 206 is rotatably connected inside the motor housing and its axial movement is restricted by the motor housing. At the same time, one end of the rotor shaft 206 is connected to the input shaft 13. The rotor assembly 203 is sleeved on the rotor shaft 206 and rotates synchronously with it. The first stator assembly 202 and the second stator assembly 204 are fixedly disposed inside the motor housing and arranged on both sides of the rotor assembly 203, forming two axial air gaps respectively. The axial flux motor 2 also includes an axial adjustment member 209, which is fixedly installed on the rotor shaft 206 and abuts against the rotor assembly 203. The axial adjustment member 209 has a preset thickness and is used to limit the two axial air gaps to a target value.

[0045] The above design clarifies that within the axial flux motor 2, the motor housing restricts the axial movement of the rotor shaft 206. In other words, the rotor shaft 206 can only rotate around its own axis within the motor housing. One end of the rotor shaft 206 is connected to the input shaft 13. However, during operation, the possible axial movement of the input shaft 13 will not affect the rotor shaft 206. Structurally, the axial flux motor 2, as an independent sub-component, is not affected by other components. This is completely different from the structure in the prior art where the rotor shaft 206 is coaxial with the input shaft 13 and is affected by the axial movement of the input shaft 13.

[0046] Under this design concept, the axial air gap adjustment is decoupled from the reducer 1, so the axial air gap can be preset. Specifically, the first stator assembly 202 and the second stator assembly 204 are fixedly connected to the motor housing. The two will not move relative to the rotor shaft 206 in the axial direction. Then, the axial position of the rotor assembly 203 on the rotor shaft 206 is fixed by the axial adjustment component 209, which can ensure that the rotor assembly 203 and the first stator assembly 202 and the second stator assembly 204 are relatively stationary in the axial direction. Therefore, the size of the two axial air gaps is fixed.

[0047] When the deviation between the two axial air gaps reaches or exceeds 0.05mm, magnetic field asymmetry will occur, the excitation current will increase abnormally, the overall efficiency of the motor will decrease by 5% to 15%, and the torque fluctuation range can rise to more than 3 times that of the uniform air gap state. At the same time, the non-uniform air gap will generate unbalanced axial magnetic pull, which will significantly increase the additional load on the bearing and accelerate the wear rate by 2 to 3 times. In severe cases, it will cause rotor rubbing failure. Therefore, this application calculates and selects an axial adjustment component 209 with a suitable preset thickness to adjust the deviation value of the two axial air gaps and control it within the target value, that is, within 0.05mm.

[0048] In this embodiment, the two axial air gaps are the first axial air gap and the second axial air gap. The rotor assembly 203 includes a rotor hub 2032 and a plurality of permanent magnets 2031 symmetrically arranged on both sides of the rotor hub 2032. The permanent magnets 2031 on the rotor hub 2032 facing the first stator assembly 202 form the first axial air gap with the first stator assembly 202. The permanent magnets 2031 on the rotor hub 2032 facing the second stator assembly 204 form the second axial air gap with the second stator assembly 204.

[0049] A key point in this application is that the preset thickness of the axial adjustment member 209 is determined based on the dimensions of the motor housing, rotor shaft 206, rotor assembly 203, first stator assembly 202, second stator assembly 204, and first bearing 208, and satisfies the following: S = δ1 + F1 - G2 - E1 - Z2 - L2, Wherein, S is the preset thickness of the axial adjustment component 209, δ1 is the axial dimension of the first axial air gap, F1 is the axial thickness of the first stator assembly 202, G2 is the axial distance between one end face 2012 of the rotor hub 2032 and the same end face 2012 of the permanent magnet 2031 on the same side, E1 is the axial thickness of the first bearing 208, Z2 is the axial thickness of the shoulder 2063, and L2 is the axial distance between the first mounting surface 2011 and the second mounting surface 2013. The axial dimension δ1 of the first axial air gap satisfies: δ1=0.5×(L1-F1-G1-F2-D2), Wherein, L1 is the axial distance between the first mounting surface 2011 and the end face 2012, G1 is the axial distance between the outer surfaces of the two permanent magnets 2031, F2 is the axial thickness of the second stator assembly 204, and D2 is the axial distance between the third mounting surface 2051 and the fourth mounting surface 2053.

[0050] To clarify, in order to ensure that the deviation between the two axial gaps is less than 0.05mm, the two axial gaps are equal during the calculation, that is, the theoretical deviation should be 0. Also, from a structural point of view, since the first stator assembly 202 and the second stator assembly 204 are symmetrically arranged on both sides of the rotor assembly 203, the two axial gaps should theoretically be equal. Therefore, in the specific calculation process, only the first axial air gap is calculated.

[0051] It is clear from the two formulas above that the calculation of the preset thickness of the axial adjustment component 209 is strictly limited to the size range of the internal parts of the motor and does not involve any size parameters of the reducer 1. This achieves the purpose of decoupling the axial air gap adjustment from the reducer 1 from a mathematical perspective. Its dimensional chain depends only on and is limited to the axial flux motor 2 itself, avoiding the introduction of the internal assembly dimensional chain of the reducer 1 when it is coaxial with the input shaft 13 of the reducer 1. This would cause the dimensional chain to be too long and difficult to adjust during axial air gap adjustment, thereby greatly reducing the requirements for the assembly dimensional tolerance chain of the reducer 1 and improving the assembly efficiency and the accuracy of axial air gap control.

[0052] The above formula can also provide guidance at the design level. By referring to the above formula, the structural design of the axial flux motor 2 can be quickly transformed into an adaptive design formula, thereby ensuring that the two axial air gaps are equal in design. This ensures that the deviation between the two axial air gaps is less than 0.05mm after assembly. The specific adjustments can be made by those skilled in the art based on the above formula and the actual structural design.

[0053] In practical applications, the axial adjustment component 209 can be an adjustment shim. The adjustment shims are graded in 0.01mm thickness. By calculating and selecting an adjustment shim of appropriate thickness using the above formula, the difference between the first axial air gap and the second axial air gap can be controlled within 0.05mm, ensuring the stable performance of the axial flux motor 2.

[0054] In this embodiment, the rotor shaft 206 has a shoulder 2063, and the axial adjustment member 209 is located between the shoulder 2063 and the rotor assembly 203, with one side abutting against the shoulder 2063 and the other side abutting against the rotor assembly 203, thereby fixing the axial position of the rotor assembly 203 on the rotor shaft 206; the rotor shaft 206 also has a first groove 2061 and a second groove 2062, which are located on the axial sides of the shoulder 2063, respectively. A first retaining ring 207 is embedded in the first groove 2061, and a first retaining ring 207 is embedded in the second groove 2062. A second retaining ring 211 is provided; a first bearing 208 and a second bearing 210 are also sleeved on the rotor shaft 206. The first bearing 208 and the second bearing 210 are respectively located on both sides of the rotor assembly 203 along the axial direction. One side of the inner ring of the first bearing 208 abuts against the first retaining ring 207 and the other side abuts against the shoulder 2063. One side of the inner ring of the second bearing 210 abuts against the second retaining ring 211 and the other side abuts against the rotor assembly 203. The first retaining ring 207 and the second retaining ring 211 limit the first bearing 208, the second bearing 210 and the rotor assembly 203 along the axial direction on the rotor shaft 206.

[0055] With the above configuration, the first retaining ring 207 and the shoulder 2063 clamp the inner ring of the first bearing 208 from both sides, and the second retaining ring 211 and the rotor assembly 203 clamp the inner ring of the second bearing 210. The shoulder 2063 restricts the axial movement of the axial adjustment member 209 and the rotor assembly 203. In this way, all rotating parts on the rotor shaft 206 are completely limited along the axial direction, eliminating axial movement between parts and ensuring the stability of the two axial air gaps.

[0056] In this embodiment, the motor housing includes a motor housing 201 and a motor end cover 205. The motor housing 201 and the motor end cover 205 are detachably fixedly connected. The first stator assembly 202 is fixedly mounted on the motor housing 201, and the second stator assembly 204 is fixedly mounted on the motor end cover 205. The outer ring of the first bearing 208 abuts against the motor housing 201, and the outer ring of the second bearing 210 abuts against the motor end cover 205. The rotor shaft 206 is rotatably connected to the motor housing through the first bearing 208 and the second bearing 210, and its axial movement is restricted by the motor housing.

[0057] With the above configuration, the outer rings of the first bearing 208 and the second bearing 210 abut against the motor housing 201 and the motor end cover 205 respectively, constraining the axial position of the rotor shaft 206 and the rotating components within the motor housing. This allows the rotor shaft 206 to be directly constrained by the motor housing rather than by the reducer 1, thus making the axial flux motor 2 an independent component. The first stator assembly 202 and the second stator assembly 204 are fixed to the motor housing 201 and the motor end cover 205 respectively. The axial air gap is entirely determined by the internal dimensional chain of the axial flux motor 2 and is independent of external components.

[0058] More specifically, the motor housing 201 has a first mounting surface 2011 and an end face 2012, and the motor end cover 205 has a third mounting surface 2051 and a fourth mounting surface 2053. When the motor housing 201 and the motor end cover 205 are fitted together, the end face 2012 abuts against the fourth mounting surface 2053. When the first stator assembly 202 is assembled, its side facing away from the rotor assembly 203 abuts against the first mounting surface 2011. When the second stator assembly 204 is assembled, its side facing away from the rotor assembly 203 abuts against the third mounting surface 2051. 1. Abutment; The motor housing 201 also has a second mounting surface 2013, and the motor end cover 205 also has a positioning surface 2052. The outer ring of the first bearing 208 abuts against the second mounting surface 2013 on the side facing the first retaining ring 207, and the outer ring of the second bearing 210 abuts against the positioning surface 2052 on the side facing the second retaining ring 211. After the axial positions of the first stator assembly 202, the rotor assembly 203 and the second stator assembly 204 are fixed, the target value is that the axial size deviation of the two axial air gaps is less than 0.05mm.

[0059] In this embodiment, the reducer 1 further includes a reducer housing 11 and an output flange 12. The reducer housing 11 is detachably and fixedly connected to the motor housing 201. The input shaft 13 is rotatably mounted inside the reducer housing 11. The output flange 12 is sleeved on one end of the input shaft 13. A low-speed shaft 9 is also fixedly connected to the output flange 12. The low-speed shaft 9 passes through the input shaft 13 and the rotor shaft 206 in sequence and is connected to the encoder assembly 6. The axial flux motor 2 is also detachably and fixedly connected to a driver cover 4 at the end opposite to the reducer 1. A driver 3 is provided inside the driver cover 4 and is mounted on the motor end cover 205. A bushing 8 is fixedly provided on the driver cover 4. The bushing 8 is connected to the end of the low-speed shaft 9 and is used to support the low-speed shaft 9.

[0060] More specifically, both sides of the motor housing are provided with positioning stops and threaded holes, and the corresponding surfaces of the reducer housing 11 and the driver cover 4 are provided with corresponding positioning stops and through holes. The three are centered by the positioning stops and are detachably connected and fixed by fasteners.

[0061] In addition, an inner support frame 7 is fixedly installed at the end of the low-speed shaft 9, and an outer support frame 5 is fixedly installed at the end of the rotor shaft 206 away from the reducer 1. The encoder assembly 6 includes an encoder circuit board 61, an outer induction ring 62, and an inner induction ring 63. The outer induction ring 62 is connected to the outer support frame 5 and rotates synchronously with the rotor shaft 206. It is used to collect the speed and number of revolutions of the axial flux motor 2 as input signals. The inner induction ring 63 is connected to the inner support frame 7 and rotates synchronously with the low-speed shaft 9. It is used to collect the speed and number of revolutions of the axial flux motor 2 as output signals. A reading head is fixed on the encoder circuit board 61. The reading head is arranged opposite to the outer induction ring 62 and the inner induction ring 63. It is used to read the signals of the outer induction ring 62 and the inner induction ring 63.

[0062] The rotary joint module of this application is assembled according to the following steps: First, the axial flux motor 2 is pre-assembled independently, including: 1. Press the first stator assembly 202 and the second stator assembly 204 into the motor housing 201 and the motor end cover 205 respectively; 2. Select an axial adjustment component 209 of appropriate thickness according to the dimensions of each part, and press the axial adjustment component 209, the first bearing 208, the second bearing 210 and the rotor assembly 203 onto the rotor shaft 206, and limit the two ends with a first retaining ring 207 and a second retaining ring 211 of appropriate thickness respectively; 3. Assemble the rotor shaft 206 and the motor end cover 205 as a whole and install them into the motor housing 201; The second step is the installation of driver 3 and encoder assembly 6, including: 4. Fix the outer sensing ring 62 on the outer support frame 5, fix the inner sensing ring 63 on the inner support frame 7, and fix the encoder circuit board 61 on the driver cover 4. 5. Install the driver 3 onto the motor end cover 205; Finally, there is the overall system integration, including: 6. Align and install the input shaft 13 of the reducer 1 with the rotor shaft 206 until the positioning stop on the motor housing 201 is completely fitted with the positioning stop on the reducer housing 11, and connect them with fasteners. 7. Pass the low-speed shaft 9 through the input shaft 13 and the rotor shaft 206 from one side of the reducer 1, and fix it on the output flange 12; 8. Install the outer support frame 5 on the end of the rotor shaft 206 away from the reducer 1, and install the inner support frame 7 on the end of the low-speed shaft 9; 9. Fix the driver cover 4 to the motor end cover 205, and fix the bushing 8 on the driver cover 4 so that the end of the low-speed shaft 9 is inserted into the bushing 8 for support, thus completing the assembly.

[0063] This embodiment provides a stator-rotor air gap control method, which can be used in the axial flux motor 2 in the above-mentioned rotary joint module. The control method includes the following steps: Step A: Obtain the dimensional values ​​of each component inside the axial flux motor 2; Step B: Based solely on the obtained dimensional values ​​of each component inside the axial flux motor 2, calculate the target value of the axial air gap between the stator assembly and the rotor assembly 203, and calculate the preset thickness value of the axial adjustment component 209. The calculation of the target value of the axial air gap and the preset thickness value of the axial adjustment component 209 includes the following steps: Step a: Calculate the target values ​​of the first axial air gap δ1 and the second axial air gap δ2 based on the dimensions of the motor housing 201, motor end cover 205, rotor assembly 203, first stator assembly 202, and second stator assembly 204. δ1=δ2= 0.5×(L1-F1-G1-F2-D2), Wherein, L1 is the axial distance between the first mounting surface 2011 and the end face 2012, G1 is the axial distance between the outer surfaces of the two permanent magnets 2031, F2 is the axial thickness of the second stator assembly 204, and D2 is the axial distance between the third mounting surface 2051 and the fourth mounting surface 2053. Step b: Calculate the distance L0 between the first mounting surface 2011 and the opposite surface of the rotor hub 2032. L0 = δ1 + F1 - G2, Wherein, F1 is the axial thickness of the first stator assembly 202, and G2 is the axial distance between the end face 2012 on one side of the rotor hub 2032 and the end face 2012 on the same side of the permanent magnet 2031. Step c: Calculate the preset thickness S of the axial adjustment component 209: S= L0-E1-Z2-L2=δ1+F1-G2-E1-Z2-L2, Wherein, E1 is the axial thickness of the first bearing 208, Z2 is the axial thickness of the shoulder 2063, and L2 is the axial distance between the first mounting surface 2011 and the second mounting surface 2013. After step B, calculate the thickness H1 of the first retaining ring 207 and the thickness H2 of the second retaining ring 211 respectively: H1=Z3-E1, H2=Z1-Z3-Z2-G3-E2-S, Wherein, Z3 is the distance between the outer wall of the first groove 2061 and the inner wall of the shoulder 2063, Z1 is the axial distance between the outer wall of the first groove 2061 and the outer wall of the second groove 2062, G3 is the axial thickness of the rotor hub 2032, and E2 is the axial thickness of the second bearing 210.

[0064] Step C: Select an axial adjustment piece 209 with the preset thickness value and install it on the rotor shaft 206 to fix the axial position of the rotor assembly 203, thereby adjusting the axial air gap and limiting it to the target value.

[0065] In step B of the above method, "based solely on the dimensional values ​​of each component inside the axial flux motor 2" is the core limitation of this method, which is significantly different from the existing schemes in the background art where the axial air gap is affected by the assembly dimension chain of the reducer 1. This method strictly limits the adjustment process of the axial air gap to be completed independently inside the axial flux motor 2, so that the axial flux motor 2 can be pre-adjusted as an independent sub-component before being assembled with external components. This completely eliminates the influence of the external dimension chain on the accuracy of the axial air gap, simplifies the overall assembly process, and improves the efficiency of mass production and maintenance performance.

[0066] This application provides a specific embodiment: The motor housing 201 provided in this embodiment has an axial distance L1 between the first mounting surface 2011 and the end surface 2012 of 33.5 mm, and an axial distance L2 between the first mounting surface 2011 and the second mounting surface 2013 of 1 mm. The motor end cover 205 provided in this embodiment has an axial distance D1 between the positioning surface 2052 and the fourth mounting surface 2053 of 5mm, and an axial distance D2 between the third mounting surface 2051 and the fourth mounting surface 2053 of 1.5mm. The rotor assembly 203 provided in this embodiment has an axial distance G1 between the outer surfaces of the permanent magnets 2031 on both sides, a axial distance G2 between the end face 2012 on one side of the rotor hub 2032 and the end face 2012 on the same side of the permanent magnet 2031, a axial thickness G3 of 10.5mm. The first stator assembly 202 and the second stator assembly 204 provided in this embodiment have the same structural dimensions, and their axial thickness F1=F2=11.8mm; The rotor shaft 206 provided in this embodiment has an axial distance Z1 of 29.5 mm between the outer wall of the first groove 2061 and the outer wall of the second groove 2062, an axial thickness Z2 of 2.5 mm, and a distance Z3 of 8 mm between the outer wall of the first groove 2061 and the inner wall of the shoulder 2063. In this embodiment, the first bearing 208 and the second bearing 210 have the same structural dimensions, and their axial thickness E1=E2=7mm. Based on the dimensional data of the above parts, the following can be calculated: δ1=δ2= 0.5×(L1-F1-G1-F2-D2)=0.5×(33.5-11.8-6.8-11.8-1.5)=0.8mm; L0=δ1+F1-G2=0.8+11.8-1.6=11mm; S= L0-E1-Z2-L2=11-7-2.5-1=0.5mm; H1 = Z3 - E1 = 8 - 7 = 1 mm; H2=Z1-Z3-Z2-G3-E2-S=29.5-8-2.5-10.5-7-0.5=1mm; Based on the above calculations, it can be determined that an axial adjustment component 209 with a thickness of 0.5 mm is required to ensure that both the first and second axial air gaps are 0.8 mm. At the same time, the rotor shaft 206 is limited at both ends by a first retaining ring 207 and a second retaining ring 211 with a thickness of 1 mm.

[0067] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A rotary joint module, characterized in that, include: A speed reducer having an input shaft; An axial flux motor includes a motor housing, a rotor shaft, a rotor assembly, a first stator assembly, and a second stator assembly. The motor housing is detachably fixedly connected to the reducer. The rotor shaft is rotatably connected inside the motor housing and its axial movement is restricted by the motor housing. At the same time, one end of the rotor shaft is connected to the input shaft. The rotor assembly is sleeved on the rotor shaft and rotates synchronously with it. The first stator assembly and the second stator assembly are fixedly disposed inside the motor housing and arranged on both sides of the rotor assembly, forming two axial air gaps respectively. The axial flux motor is also provided with an axial adjustment component, which is fixedly installed on the rotor shaft and abuts against the rotor assembly. The axial adjustment component has a preset thickness and is used to limit the two axial air gaps to a target value.

2. A rotary joint module as described in claim 1, characterized in that, The rotor shaft has a shoulder, and the axial adjustment member is located between the shoulder and the rotor assembly, with one side abutting against the shoulder and the other side abutting against the rotor assembly, thereby fixing the axial position of the rotor assembly on the rotor shaft.

3. A rotary joint module as described in claim 2, characterized in that, The rotor shaft also has a first groove and a second groove, which are located on opposite axial sides of the shoulder. A first retaining ring is embedded in the first groove, and a second retaining ring is embedded in the second groove. A first bearing and a second bearing are also fitted on the rotor shaft. The first bearing and the second bearing are located on opposite axial sides of the rotor assembly. One side of the inner ring of the first bearing abuts against the first retaining ring, and the other side abuts against the shoulder. One side of the inner ring of the second bearing abuts against the second retaining ring, and the other side abuts against the rotor assembly. The first retaining ring and the second retaining ring axially confine the first bearing, the second bearing, and the rotor assembly on the rotor shaft.

4. A rotary joint module as described in claim 3, characterized in that, The motor housing includes a motor housing and a motor end cover. The motor housing and the motor end cover are detachably fixedly connected. The first stator assembly is fixedly mounted on the motor housing, and the second stator assembly is fixedly mounted on the motor end cover. The outer ring of the first bearing abuts against the motor housing, and the outer ring of the second bearing abuts against the motor end cover. The rotor shaft is rotatably connected to the motor housing through the first bearing and the second bearing, and its axial movement is restricted by the motor housing.

5. A rotary joint module as described in claim 4, characterized in that, The motor housing has a first mounting surface and an end face, and the motor end cover has a third mounting surface and a fourth mounting surface. When the motor housing and the motor end cover are fitted together, the end face abuts against the fourth mounting surface. When the first stator assembly is assembled, its side facing away from the rotor assembly abuts against the first mounting surface. When the second stator assembly is assembled, its side facing away from the rotor assembly abuts against the third mounting surface. The motor housing also has a second mounting surface, and the motor end cover also has a positioning surface. The outer ring of the first bearing abuts against the second mounting surface on the side facing the first retaining ring, and the outer ring of the second bearing abuts against the positioning surface on the side facing the second retaining ring. After the axial positions of the first stator assembly, the rotor assembly, and the second stator assembly are fixed, the target value is that the axial size deviation of the two axial air gaps is less than 0.05 mm.

6. A rotary joint module as described in claim 5, characterized in that, The two axial air gaps are a first axial air gap and a second axial air gap, respectively. The rotor assembly includes a rotor hub and a plurality of permanent magnets symmetrically arranged on both sides of the rotor hub. The permanent magnets on the rotor hub facing the first stator assembly form the first axial air gap with the first stator assembly, and the permanent magnets on the rotor hub facing the second stator assembly form the second axial air gap with the second stator assembly.

7. A rotary joint module as described in claim 6, characterized in that, The preset thickness of the axial adjustment component is determined based on the dimensions of the motor housing, the rotor shaft, the rotor assembly, the first stator assembly, the second stator assembly, and the first bearing, and satisfies the following: S = δ1 + F1 - G2 - E1 - Z2 - L2, Wherein, S is the preset thickness of the axial adjustment component, δ1 is the axial dimension of the first axial air gap, F1 is the axial thickness of the first stator assembly, G2 is the axial distance between one end face of the rotor hub and the same end face of the permanent magnet on the same side, E1 is the axial thickness of the first bearing, Z2 is the axial thickness of the shoulder, and L2 is the axial distance between the first mounting surface and the second mounting surface. The axial dimension δ1 of the first axial air gap satisfies: δ1=0.5×(L1-F1-G1-F2-D2), Wherein, L1 is the axial distance between the first mounting surface and the end face, G1 is the axial distance between the outer surfaces of the permanent magnets on both sides, F2 is the axial thickness of the second stator assembly, and D2 is the axial distance between the third mounting surface and the fourth mounting surface.

8. A rotary joint module as described in claim 4, characterized in that, The reducer also includes a reducer housing and an output flange. The reducer housing is detachably and fixedly connected to the motor housing. The input shaft is rotatably mounted inside the reducer housing. The output flange is sleeved on one end of the input shaft. A low-speed shaft is also fixedly connected to the output flange. The low-speed shaft passes through the input shaft and the rotor shaft in sequence and is connected to the encoder assembly. A driver cover is also detachably and fixedly connected to the end of the axial flux motor facing away from the reducer. A driver is disposed inside the driver cover and is mounted on the motor end cover. A bushing is fixedly disposed on the driver cover and is connected to the end of the low-speed shaft. An inner support frame is fixedly installed at the end of the low-speed shaft, and an outer support frame is fixedly installed at the end of the rotor shaft away from the reducer. The encoder assembly includes an encoder circuit board, an outer induction ring, and an inner induction ring. The outer induction ring is connected to the outer support frame and rotates synchronously with the rotor shaft, and is used to collect the speed and number of revolutions of the axial flux motor as input signals. The inner induction ring is connected to the inner support frame and rotates synchronously with the low-speed shaft, and is used to collect the speed and number of revolutions of the axial flux motor as output signals. A read head is fixed on the encoder circuit board, and the read head is arranged opposite to the outer induction ring and the inner induction ring, and is used to read the signals of the outer induction ring and the inner induction ring.

9. A method for controlling the air gap between the stator and rotor, characterized in that, The control method for the axial flux motor used in the rotary joint module as described in any one of claims 1 to 8 includes the following steps: Step A: Obtain the dimensional values ​​of each component inside the axial flux motor; Step B: Based solely on the obtained dimensional values ​​of each component inside the axial flux motor, calculate the target value of the axial air gap between the stator assembly and the rotor assembly, and calculate the preset thickness value of the axial adjustment component. Step C: Select an axial adjustment component with the preset thickness value and install it on the rotor shaft to fix the axial position of the rotor assembly, thereby adjusting the axial air gap and limiting it to the target value.

10. The stator-rotor air gap control method as described in claim 9, characterized in that, In step B, calculating the target value of the axial air gap and the preset thickness value of the axial adjustment component includes the following steps: Step a: Calculate the target values ​​of the first axial air gap δ1 and the second axial air gap δ2 based on the dimensions of the motor housing, motor end cover, rotor assembly, first stator assembly, and second stator assembly. δ1=δ2= 0.5×(L1-F1-G1-F2-D2), Where L1 is the axial distance between the first mounting surface and the end face, G1 is the axial distance between the outer surfaces of the two permanent magnet bodies, F2 is the axial thickness of the second stator assembly, and D2 is the axial distance between the third mounting surface and the fourth mounting surface. Step b: Calculate the distance L0 between the first mounting surface and the opposite surface of the rotor hub. L0 = δ1 + F1 - G2, Where F1 is the axial thickness of the first stator assembly, and G2 is the axial distance between one end face of the rotor hub and the same end face of the permanent magnet on the same side. Step c: Calculate the preset thickness S of the axial adjustment component: S= L0-E1-Z2-L2=δ1+F1-G2-E1-Z2-L2, Where E1 is the axial thickness of the first bearing, Z2 is the axial thickness of the shoulder, and L2 is the axial distance between the first mounting surface and the second mounting surface. After step B, calculate the thickness H1 of the first retaining ring and the thickness H2 of the second retaining ring respectively: H1=Z3-E1, H2=Z1-Z3-Z2-G3-E2-S, Where Z3 is the distance between the outer wall of the first groove and the inner wall of the shoulder, Z1 is the axial distance between the outer wall of the first groove and the outer wall of the second groove, G3 is the axial thickness of the rotor hub, and E2 is the axial thickness of the second bearing.

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