Coreless motor having protective sleeve and potting method therefor

Abstract

The present invention provides a coreless motor having a protective sleeve and a potting method therefor. The coreless motor having a protective sleeve comprises a stator assembly, a rotor assembly, and a housing. The stator assembly is arranged in the housing; the stator assembly is provided with a cavity penetrating in the axial direction; the rotor assembly penetrates the cavity; the housing is sleeved on the outer wall of the stator assembly, and two ends of the housing extend out of two ends of the stator assembly; a stator protection sleeve is provided on the inner wall of the stator assembly; two ends of the stator protection sleeve extend out of the two ends of the stator assembly; stator encapsulation layers are provided at the two ends of the stator assembly; the stator protection sleeve, the housing, and the stator encapsulation layers isolate and seal the stator assembly; the rotor assembly comprises magnetic steel and a shaft core; the shaft core penetrates the center of the magnetic steel; a rotor protection sleeve is provided on the outer wall of the magnetic steel; two ends of the rotor protection sleeve extend out of two ends of the magnetic steel; a rotor encapsulation layer is provided at the end of the magnetic steel; and the rotor protection sleeve and the rotor encapsulation layer isolate and seal the magnetic steel. The present invention achieves the protection of a motor having no biocompatible material.

Description

A hollow cup motor with a protective cover and a potting method thereof

[0001] Cross-reference to related applications

[0002] This patent application claims priority to the Chinese patent application filed on February 26, 2024, with application number 202410205840.5 and invention name “A hollow cup motor with a protective cover and its potting method”. The full text of the above application is incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of coreless motors, and in particular to a coreless motor with a protective sleeve and a potting method thereof. Background Art

[0004] Coreless motors are often used in medical devices due to their compact size, high efficiency, and stable operation. In addition to these features, biocompatibility and safety are also essential requirements for medical devices. Therefore, careful consideration must be given to motor material selection and insulation protection to address various unexpected situations that may arise when the motor is operating in the human body. Under these operating requirements, designing a motor structure with a reliable structure, strong sealing, and improved electromagnetic performance and output torque is paramount.

[0005] Currently, the commonly used isolation protection methods for implantable hollow cup motors are polymer film coating or glue potting. The non-biocompatible parts of the motor, such as the iron core, coil, and magnet, are covered to isolate the blood and protect the metal materials from oxidation and falling off and flowing into the blood, causing human contamination. However, whether it is polymer film coating or glue potting, its reliability is not high, and it is inevitable that there will be low yields, collision vibration, and the risk of falling off under alternating hot and humid temperatures. A highly reliable protective structure is needed to ensure the protection of the motor's non-biocompatible materials.

[0006] Therefore, it is necessary to design a hollow cup motor with a protective cover and a potting method thereof to solve the above problems.

[0007] Summary of the Invention

[0008] The technical problem solved by the embodiment of the present invention is mainly to provide a protective cover for protecting the stator assembly and the rotor assembly and to achieve sealing and isolation through the packaging layer, thereby protecting the non-biocompatible materials of the motor.

[0009] In order to solve the above technical problems, an embodiment of the present invention provides a coreless motor with a protective cover and a potting method thereof. The hollow cup motor with a protective sleeve comprises a stator assembly, a rotor assembly and a casing; the stator assembly is arranged in the casing and is provided with a cavity extending axially therethrough, and the rotor assembly is rotatably passed through the cavity, and is characterized in that the casing is sleeved on the outer wall of the stator assembly and two ends of the casing extend axially beyond the two ends of the stator assembly, the inner wall of the stator assembly is provided with a stator protective sleeve, the two ends of the stator protective sleeve extend axially beyond the two ends of the stator assembly, the two ends of the stator assembly are provided with a stator packaging layer, the stator protective sleeve, the casing and the stator packaging layer isolate and seal the stator assembly; the rotor assembly comprises a magnet and a shaft core, the shaft core passes through the center of the magnet, the outer wall of the magnet is provided with a rotor protective sleeve, the two ends of the rotor protective sleeve extend axially beyond the two ends of the magnet, the ends of the magnet are provided with a rotor packaging layer, and the rotor protective sleeve and the rotor packaging layer isolate and seal the magnet.

[0010] Optionally, both the stator protective cover and the rotor protective cover are made of biocompatible metal materials, and the biocompatible metal materials include stainless steel 316, stainless steel 317, titanium alloy, cobalt alloy, gold, silver, platinum and memory metal.

[0011] Optionally, the stator protective cover and the rotor protective cover are both cylindrical tube structures, and are both welded from metal sheets made of the biocompatible metal material, and the thickness of the metal sheets is 0.01 mm-0.05 mm.

[0012] Optionally, the stator packaging layer and the rotor packaging layer are both formed by glue potting.

[0013] Optionally, the outer diameter of the stator protective cover is smaller than the inner diameter of the stator assembly, the minimum difference between the outer diameter of the stator protective cover and the inner diameter of the stator assembly is 0.02 mm, the stator protective cover and the stator assembly are coaxially arranged, so that the minimum gap formed between the stator protective cover and the stator assembly is 0.01 mm, and the stator protective cover and the stator assembly are bonded by glue coated on the outer wall of the stator protective cover.

[0014] Optionally, the difference between the length of the stator protective cover and the length of the stator assembly is 1 mm-2 mm; the distance between the end of the stator protective cover and the end of the stator assembly at the same end is 0.5 mm-1 mm, and the stator encapsulation layer is arranged between the end of the stator protective cover and the end of the stator assembly at the same end.

[0015] Optionally, the inner diameter of the rotor protection cover is larger than the outer diameter of the magnetic steel, the difference between the inner diameter of the rotor protection cover and the outer diameter of the magnetic steel is at least 0.02 mm, the inner diameter of the rotor protection cover is coaxially arranged with the magnetic steel, so that the minimum gap formed between the rotor protection cover and the magnetic steel is 0.01 mm, and the rotor protection cover and the magnetic steel are bonded by glue coated on the inner wall of the rotor protection cover.

[0016] Optionally, the difference between the length of the rotor protective cover and the length of the magnetic steel is 1mm-2mm; the distance between the end of the rotor protective cover and the end of the magnetic steel at the same end is 0.5mm-1mm, and the rotor encapsulation layer is arranged between the end of the rotor protective cover and the end of the magnetic steel at the same end.

[0017] Optionally, the outer diameter of the stator assembly is equal to the inner diameter of the housing, and the stator assembly is connected to the housing with a clearance fit.

[0018] Based on the same concept, an embodiment of the present invention further provides a potting method for a coreless motor with a protective sleeve, wherein the coreless motor with a protective sleeve comprises a stator assembly, a rotor assembly, and a housing; the stator assembly is disposed in the housing and is provided with a cavity extending axially therethrough; the rotor assembly is rotatably disposed in the cavity; the rotor assembly comprises a magnet and a shaft core, wherein the shaft core is disposed at the center of the magnet; and the method comprises the following steps:

[0019] Providing the stator assembly and the stator protective sleeve, sleeve-mounting the stator protective sleeve on the inner wall of the stator assembly, and controlling the two ends of the stator protective sleeve to extend axially beyond the two ends of the stator assembly, and the two ends of the stator protective sleeve are equidistant from the two ends of the stator assembly in the axial direction;

[0020] Providing the housing, sleeved on the outer wall of the stator assembly on which the stator protective cover is installed, and controlling the two ends of the housing to extend axially beyond the two ends of the stator assembly, so that a stator potting space is formed between the outer wall of the stator protective cover, the inner wall of the housing, the end face of the stator assembly, and the end face of the stator protective cover;

[0021] dripping glue into the stator potting space to form a stator packaging layer to isolate and seal the stator assembly;

[0022] Provide the rotor assembly and the rotor protective cover, and sleeve the rotor protective cover over the outer wall of the magnetic steel. Control the two ends of the rotor protective cover to extend axially beyond the two ends of the magnetic steel, and keep the two ends of the rotor protective cover equidistant from the two ends of the magnetic steel in the axial direction. A rotor potting space is formed between the outer wall of the shaft core, the inner wall of the rotor protective cover, the end surface of the magnetic steel, and the end surface of the rotor protective cover.

[0023] Glue is dripped into the rotor potting space to form a rotor packaging layer to isolate and seal the magnetic steel.

[0024] Optionally, the outer diameter of the stator protective cover is smaller than the inner diameter of the stator assembly, and the stator protective cover and the stator assembly are coaxially arranged, so that the minimum difference between the outer diameter of the stator protective cover and the inner diameter of the stator assembly is 0.02 mm, and the minimum gap formed between the stator protective cover and the stator assembly is 0.01 mm. The potting method comprises the following steps:

[0025] Apply glue on the outer wall of the stator protective sleeve,

[0026] The stator protection sleeve is sleeved on the inner wall of the stator assembly so that the stator protection sleeve and the stator assembly are bonded together as a whole.

[0027] Optionally, the inner diameter of the rotor protective cover is larger than the outer diameter of the magnetic steel, the minimum difference between the inner diameter of the rotor protective cover and the outer diameter of the magnetic steel is 0.02 mm, the inner diameter of the rotor protective cover is coaxial with the magnetic steel, so that the minimum gap formed between the rotor protective cover and the magnetic steel is 0.01 mm, and the potting method comprises the following steps:

[0028] Apply glue on the inner wall of the rotor protective cover,

[0029] The rotor protection cover is sleeved on the outer wall of the magnetic steel so that the rotor protection cover and the rotor assembly are bonded together.

[0030] Compared with the prior art, the technical solution of the embodiment of the present invention has beneficial effects.

[0031] For example, the hollow cup motor with a protective cover and its potting method of the present invention use a protective cover to protect the stator assembly and the rotor assembly, and form an encapsulation layer by dripping glue at the end to achieve sealing and isolation, thereby realizing reliable protection of the non-biocompatible materials of the motor; especially when water enters the inside of the motor, the encapsulation layer is not easy to fall off under the water pressure flushing, and the reliability is high.

[0032] For another example, the protective cover is made of metal sheets, usually titanium alloy sheets. Titanium alloy has good biocompatibility, high strength, and stable structure, which is conducive to providing stable and reliable protection. Titanium alloy has low electrical conductivity, which can effectively filter the time and space harmonics in the stator magnetic field, reduce the eddy current loss on the rotor surface, reduce the heat of the rotor, improve the efficiency of the motor, and ensure the safety of the motor operation; the welding process is simple and easy to produce, and the small thickness of the metal sheet will not affect the overall size of the motor.

[0033] For another example, the protective cover extends out from both ends of the magnetic steel of the stator assembly or the rotor assembly to form a potting space, which is conducive to drip irrigation of the packaging layer to achieve sealing, while preventing the packaging layer from falling off due to vibration during motor operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a cross-sectional view of a coreless motor with a protective cover according to an embodiment of the present invention;

[0035] FIG2 is a schematic diagram of the installation of the stator assembly and the stator protective cover in an embodiment of the present invention;

[0036] FIG3 is a schematic structural diagram of a housing, a stator assembly, and a stator protective cover according to an embodiment of the present invention;

[0037] Figure 4 is an enlarged view of point A in Figure 3;

[0038] 5 is a schematic structural diagram of a rotor assembly and a rotor protection cover according to an embodiment of the present invention;

[0039] Figure 6 is an enlarged view of point B in Figure 5;

[0040] 7 is a schematic structural diagram of a stator protective cover or a rotor protective cover according to an embodiment of the present invention;

[0041] FIG8 is a schematic diagram of the metal sheet structure according to an embodiment of the present invention;

[0042] FIG9 is a schematic diagram of another metal sheet structure according to an embodiment of the present invention;

[0043] FIG10 is a schematic diagram of a model of a coreless motor without a protective cover in the prior art;

[0044] FIG11 is a schematic diagram of a model of a coreless motor with a protective cover according to an embodiment of the present invention;

[0045] FIG12 is an FFT diagram of the back electromotive force of a coreless motor without a protective cover in the prior art;

[0046] FIG13 is an FFT diagram of the back electromotive force of the coreless motor with a protective cover according to an embodiment of the present invention;

[0047] FIG14 is a torque diagram of a coreless motor without a protective sleeve in the prior art;

[0048] FIG15 is a torque diagram of a coreless motor with a protective cover according to an embodiment of the present invention;

[0049] FIG16 is a diagram of the cogging torque of a coreless motor without a protective sleeve in the prior art;

[0050] FIG17 is a torque diagram of a coreless motor with a protective cover according to an embodiment of the present invention.

[0051] In the figure: 1. Rotor protective cover; 2. Stator protective cover; 3. Rotor assembly, 31. Shaft core, 32. Magnet; 4. Stator assembly, 41. Winding coil, 42. Iron core; 5. Casing; 6. Rotor packaging layer; 7. Stator packaging layer; 8. Front cover; 9. Rear cover; 10. Connection cover. DETAILED DESCRIPTION

[0052] To make the objectives, features, and beneficial effects of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described below are merely illustrative of the present invention and are not intended to limit the present invention. Furthermore, the same or similar reference numerals may be used in the drawings to refer to the same or similar elements in different embodiments, and descriptions of the same or similar elements in different embodiments, as well as descriptions of prior art elements, features, and effects, may be omitted.

[0053] 1 to 9 , an embodiment of the present invention provides a coreless motor with a protective cover.

[0054] Specifically, the hollow cup motor with a protective sleeve includes a stator assembly 4, a rotor assembly 3 and a casing 5; the stator assembly 4 is arranged in the casing 5 and is provided with a cavity extending axially therethrough, the rotor assembly 3 is rotatably inserted into the cavity, the casing 5 is sleeved on the outer wall of the stator assembly 4 and the two ends of the casing 5 extend axially from the two ends of the stator assembly 4, the inner wall of the stator assembly 4 is provided with a stator protective sleeve 2, the two ends of the stator protective sleeve 2 extend axially from the two ends of the stator assembly 4, the two ends of the stator assembly 4 are provided with a stator packaging layer 7, the stator protective sleeve 2, the casing 5 and the stator packaging layer 7 isolate and seal the stator assembly 4; the rotor assembly 3 includes a magnet 32 ​​and a shaft core 31, the shaft core 31 is inserted into the center of the magnet 32, the outer wall of the magnet 32 ​​is provided with a rotor protective sleeve 1, the two ends of the rotor protective sleeve 1 extend axially from the two ends of the magnet 32, the end of the magnet 32 ​​is provided with a rotor packaging layer 6, the rotor protective sleeve 1 and the rotor packaging layer 6 isolate and seal the magnet 32.

[0055] In some embodiments, the outer diameter φC1 of the stator protective sleeve 2 is smaller than the inner diameter φC of the stator assembly 4. The minimum difference between the outer diameter φC1 of the stator protective sleeve 2 and the inner diameter φC of the stator assembly 4 is 0.02 mm, i.e., φC - φC1 = 0.02 mm. The maximum difference between the outer diameter φC1 of the stator protective sleeve 2 and the inner diameter φC of the stator assembly 4 is determined based on the size of the motor, suffices to ensure that there is no friction between the stator and the rotor. For example, when the outer diameter of the motor is less than 6 mm, the difference between the outer diameter φC1 of the stator protective sleeve 2 and the inner diameter φC of the stator assembly 4 can be in the range of 0.02 mm to 0.03 mm. The stator protective sleeve 2 and the stator assembly 4 are coaxially arranged so that the minimum gap formed between the stator protective sleeve 2 and the stator assembly 4 is 0.01 mm. The stator protective sleeve 2 and the stator assembly 4 are bonded together using glue applied to the outer wall of the stator protective sleeve 2. A smaller gap is provided between the stator protective cover 2 and the stator assembly 4 to facilitate coaxial nesting and bonding of the two without occupying a large radial space, thereby avoiding an increase in the size of the motor.

[0056] In some embodiments, the difference between the length D1 of the stator protective cover 2 and the length D of the stator assembly 4 is 1 mm to 2 mm, i.e., D1 - D = 1 mm to 2 mm. The stator assembly 4 includes winding coils 41 and an iron core 42, arranged sequentially from the inside to the outside. The winding coils 41 are typically arranged axially within the iron core 42, and the length D of the stator assembly 4 typically refers to the length of the iron core 42. The distance between the end of the stator protective cover 2 and the end of the stator assembly 4 at the same end is 0.5 mm to 1 mm. The stator encapsulation layer 7 is disposed between the end of the stator protective cover 2 and the end of the stator assembly 4 at the same end. The stator encapsulation layer 7 is embedded and fills the axial ends of the stator assembly 4, i.e., it fully fills the end surfaces of the stator assembly 4 along the axial direction to cover the entire area of ​​the end surfaces, ensuring a sealing effect while preventing vibration and dislodging during motor operation.

[0057] In some embodiments, the distances between the ends of the stator protective sleeve 2 and the end of the stator assembly 4 at the same end can be the same or different, that is, the axial heights of the stator encapsulation layer 7 at both ends of the stator assembly can be the same or different, as long as the potting height on one side is greater than 0.3 mm.

[0058] In some embodiments, the inner diameter φA1 of the rotor protective cover 1 is greater than the outer diameter φA of the magnet 32. The minimum difference between the inner diameter φA1 of the rotor protective cover 1 and the outer diameter φA of the magnet 32 ​​is 0.02 mm, i.e., φA1 - φA = 0.02 mm. The maximum difference between the inner diameter φA1 of the rotor protective cover 1 and the outer diameter φA of the magnet 32 ​​is determined based on the size of the motor, suffices to ensure that there is no friction between the stator and the rotor. For example, if the outer diameter of the motor is less than 6 mm, the difference between the inner diameter φA1 of the rotor protective cover 1 and the outer diameter φA of the magnet 32 ​​can be in the range of 0.02 mm to 0.03 mm. The inner diameter of the rotor protective cover 1 is coaxial with the magnet 32, such that the minimum gap between the rotor protective cover 1 and the magnet 32 ​​is 0.01 mm. The rotor protective cover 1 and the magnet 32 ​​are bonded together using glue applied to the inner wall of the rotor protective cover 1. A smaller gap is provided between the rotor protection cover 1 and the rotor assembly 3 to facilitate coaxial nesting and bonding of the two without occupying a large radial space, thereby avoiding an increase in the size of the motor.

[0059] In some embodiments, the difference between the length B1 of the rotor protective cover 1 and the length B of the magnet 32 ​​is 1 mm to 2 mm. The distance between the end of the rotor protective cover 1 and the end of the magnet 32 ​​at the same end is 0.5 mm to 1 mm. The rotor encapsulation layer 6 is disposed between the end of the rotor protective cover 1 and the end of the magnet 32 ​​at the same end. The rotor encapsulation layer 6 is embedded and fills the axial ends of the magnet 32, that is, it fully fills the axial end surfaces of the magnet 32 ​​along the axial direction to cover the entire area of ​​the end surfaces, ensuring a good seal while preventing vibration and shedding during motor operation.

[0060] In some embodiments, the distances between the ends of the rotor protective cover 1 and the ends of the magnet 32 ​​at the same end can be the same or different, that is, the axial heights of the rotor encapsulation layer 6 at both ends of the magnet can be the same or different, as long as the potting height on one side is greater than 0.3 mm.

[0061] In some embodiments, the outer diameter of the stator assembly 4 is equal to the inner diameter of the casing 5, and the stator assembly 4 is connected to the casing 5 with a clearance fit; in specific implementation, the stator protective cover 2 can be first radially glued and fixed to the stator assembly 4, and then the stator assembly 4 and the casing 5 with the assembled stator protective cover 2 are positioned by a positioning device, and then the stator assembly 4 and the casing 5 are cured and connected with glue.

[0062] In some embodiments, the stator packaging layer 7 and the rotor packaging layer 6 are both formed by glue potting.

[0063] FIG7 is a schematic diagram of the structure of a stator protective cover or a rotor protective cover in an embodiment of the present invention; FIG8 is a schematic diagram of the structure of a metal sheet in an embodiment of the present invention; FIG9 is a schematic diagram of the structure of another metal sheet in an embodiment of the present invention.

[0064] Please refer to Figures 7 to 9. Both the stator protection cover 2 and the rotor protection cover 1 have cylindrical tube structures and are welded from metal sheets. The thickness of the metal sheets is t = 0.01 mm - 0.05 mm to ensure that only plastic deformation occurs. πA / πC are the circumferences of the rotor protection cover 1 / stator protection cover 2, and B1 / D1 are the axial lengths of the rotor protection cover 1 / stator protection cover 2. The shape of the metal sheets includes but is not limited to a rectangle. Other sheet structures that can be formed into a cylindrical shape can also be used.

[0065] The metal sheets selected for the stator protective cover 2 and the rotor protective cover 1 need to be biocompatible and only produce plastic deformation at a thickness of 0.01mm-0.05mm to achieve a cylindrical structure. It is also best to have a certain electrical conductivity to achieve the function of reducing spatial harmonics. They are usually welded from titanium alloy sheets. The metal sheets can also be made of stainless steel 316, stainless steel 317, cobalt alloy, gold, silver, platinum, memory metal and other materials.

[0066] In the prior art, other motors such as permanent magnet motors also use a magnetic steel protective cover that is sleeved on the outside of the magnetic steel to achieve the roundness positioning of the surface-mounted magnetic steel and the relative positioning of the Hall element; the magnetic steel protective cover can be formed by plastic injection molding or metal machining to ensure positioning, and a certain magnetic circuit optimization is achieved when using metal materials. Compared with the magnetic steel protective cover, the rotor protective cover 1 in the embodiment of the present invention is made of a biocompatible metal material and is applied to a hollow cup motor. Since the motor volume is very small, this requires the rotor protective cover 1 to have a small wall thickness (0.01mm-0.05mm). Under this wall thickness condition, the metal material easily loses its elastic rebound ability and undergoes plastic deformation. Therefore, machining cannot be used in the manufacturing process. It is necessary to roll a metal sheet made of a biocompatible metal material into a cylindrical structure and weld it into shape, and then place it on the outside of the rotor to achieve shielding and isolation from materials that do not have biocompatibility, and it has relatively strong rigidity.

[0067] In some embodiments, the end of the stator assembly 4 is provided with an FPC (Flexible Printed Circuit), PCB (Printed Circuit Board) or a bracket to connect the winding coil 41 of the stator assembly 4 with the external power line, as well as other auxiliary parts. The parts arranged at the end of the stator assembly 4 are sealed together by the stator packaging layer 7 after being fixed.

[0068] In some embodiments, the axial end of the rotor assembly 3 is provided with auxiliary parts such as a balancing ring or a limit ring. The limit ring or the balancing ring is a part that assists in rotor positioning or satisfies dynamic balance and can be provided at both ends of the magnet. The auxiliary parts provided at the end of the rotor assembly 3 are sealed together with the rotor packaging layer 6 after being fixed. After adding the auxiliary parts, the end face of the auxiliary parts is in contact with the magnet 32, which may cause the sealing volume of the rotor packaging layer 6 on one side to be reduced.

[0069] An embodiment of the present invention further provides a potting method for a coreless motor with a protective sleeve. The coreless motor with a protective sleeve includes a stator assembly 4, a rotor assembly 3, and a housing 5. The stator assembly 4 is disposed in the housing 5 and has a cavity extending axially therethrough. The rotor assembly 3 is rotatably disposed in the cavity. The rotor assembly 3 includes a magnet 32 ​​and a shaft core 31. The shaft core 31 is disposed at the center of the magnet 32. The method includes the following steps:

[0070] Provide a stator assembly 4 and a stator protective sleeve 2. Sleeve the stator protective sleeve 2 over the inner wall of the stator assembly 4. Ensure that both ends of the stator protective sleeve 2 extend axially beyond the ends of the stator assembly 4. Ensure that both ends of the stator protective sleeve 2 are equidistant from the ends of the stator assembly 4 in the axial direction.

[0071] A casing 5 is provided, and the casing 5 is sleeved on the outer wall of the stator assembly 4 installed with the stator protective cover 2, and the two ends of the casing 5 are controlled to extend axially from the two ends of the stator assembly 4, and a stator potting space is formed between the outer wall of the stator protective cover 2, the inner wall of the casing 5, the end face of the stator assembly 4 and the end face of the stator protective cover 2; at this time, the stator protective cover 2 and the winding coil 41 of the stator assembly 4 are bonded with glue, and the glue of the stator assembly 4 and the casing 5 is cured and bonded, and the radial bonding is completed. A groove is formed between the outer wall of the stator protective cover 2 and the inner wall of the casing 5 in the axial direction, and the groove forms a stator potting space that needs to be filled with glue. The axial height limit of the glue is the end face of the stator protective cover 2, and the bottom surface is the end face of the iron core 42 and the winding coil 41 of the stator assembly 4.

[0072] Drip glue into the stator potting space to form a stator encapsulation layer 7 to isolate and seal the stator assembly 4; gradually expel the air in the stator potting space through drip irrigation to avoid the formation of bubbles that affect the sealing effect;

[0073] A rotor assembly 3 and a rotor protective cover 1 are provided, and the rotor protective cover 1 is sleeved on the outer wall of the magnet 32, and the two ends of the rotor protective cover 1 are controlled to extend axially from the two ends of the magnet 32, and in the axial direction, the two ends of the rotor protective cover 1 are respectively at equal distances from the two ends of the magnet 32, and a rotor potting space is formed between the outer wall of the shaft core 31, the inner wall of the rotor protective cover 1, the end face of the magnet 32 ​​and the end face of the rotor protective cover 1; at this time, the shaft core 31 is radially connected to the magnet 32, and the rotor protective cover 1 is radially bonded to the magnet 32. After the radial bonding is completed, a groove is formed between the outer wall of the shaft core 31 and the inner wall of the rotor protective cover 1, where the groove forms a rotor potting space that needs to be filled with glue, and the axial height limit of the glue is the end face of the rotor protective cover 1, and the bottom face is the end face of the magnet 32.

[0074] Glue is dripped into the rotor potting space to form a rotor packaging layer 6 to isolate and seal the magnetic steel 32. The air in the rotor potting space is gradually discharged through drip irrigation to avoid the formation of bubbles that affect the sealing effect.

[0075] After potting is completed, the hollow cup motor is assembled. The rotor assembly 3 with the rotor protection cover 1 installed and potted is installed into the cavity. The front end cover 8 and the rear end cover 9 for fixing the rotor assembly 3 are installed at both ends of the casing 5. The connection cover 10 for introducing the external power line is installed on the rear end cover 9 to complete the assembly.

[0076] In a specific implementation, the outer diameter φC1 of the stator protective cover 2 is smaller than the inner diameter φC of the stator assembly 4. The minimum difference between the outer diameter φC1 of the stator protective cover 2 and the inner diameter φC of the stator assembly 4 is 0.02 mm, that is, φC-φC1=0.02 mm. The stator protective cover 2 and the stator assembly 4 are coaxially arranged so that the minimum gap formed between the stator protective cover 2 and the stator assembly 4 is 0.01 mm. The potting method includes the following steps:

[0077] Apply glue to the outer wall of the stator protective sleeve 2.

[0078] The stator protection cover 2 is sleeved on the inner wall of the stator assembly 4 so that the stator protection cover 2 and the stator assembly 4 are bonded together.

[0079] In a specific implementation, the inner diameter φA1 of the rotor protective cover 1 is larger than the outer diameter φA of the magnetic steel 32. The minimum difference between the inner diameter φA1 of the rotor protective cover 1 and the outer diameter φA of the magnetic steel 32 is 0.02 mm, that is, φA1-φA=0.02 mm. The inner diameter of the rotor protective cover 1 is coaxial with the magnetic steel 32, so that the minimum gap formed between the rotor protective cover 1 and the magnetic steel 32 is 0.01 mm. The potting method includes the following steps:

[0080] Apply glue to the inner wall of the rotor protective cover 1.

[0081] The rotor protection cover 1 is sleeved on the outer wall of the magnetic steel 32 so that the rotor protection cover 1 and the rotor assembly 3 are bonded together.

[0082] FIG10 is a schematic diagram of a model of a coreless motor without a protective cover in the prior art; FIG11 is a schematic diagram of a model of a coreless motor with a protective cover in an embodiment of the present invention.

[0083] Please refer to Figures 10 and 11. The volume of the hollow cup motor without a protective cover and the hollow cup motor with a protective cover in the radial space is basically unchanged, indicating that the provision of the stator protective cover 2 and the rotor protective cover 1 has basically no effect on the volume of the hollow cup motor.

[0084] FIG12 is an FFT diagram of the back electromotive force of a coreless motor without a protective cover in the prior art; FIG13 is an FFT diagram of the back electromotive force of a coreless motor with a protective cover in an embodiment of the present invention.

[0085] Please refer to Figure 12 and Figure 13, where the horizontal axis represents frequency in KHz, and the vertical axis represents back electromotive force. The number of harmonics in the FFT decomposition of the no-load back electromotive force of the hollow cup motor with a protective cover is greatly reduced compared with the hollow cup motor without a protective cover; reducing the harmonics in the FFT decomposition of the no-load back electromotive force means reducing the component of the fundamental wave of the no-load back electromotive force, which means improving the output capacity of the motor. At the same time, reducing harmonics will also greatly improve noise and vibration.

[0086] FIG14 is a torque diagram of a coreless motor without a protective cover in the prior art; FIG15 is a torque diagram of a coreless motor with a protective cover in an embodiment of the present invention.

[0087] Please refer to Figure 14 and Figure 15, where the horizontal axis represents time in ms, and the vertical axis represents torque. The torque fluctuation of the hollow cup motor with a protective cover is 1.74mN·m, and the torque fluctuation of the hollow cup motor without a protective cover is 1.81mN·m. The torque fluctuation of the hollow cup motor with a protective cover is reduced by about 4%; as the range of torque fluctuation decreases, the operating stability of the motor is improved; the decrease in the slot torque reduces the vibration of the motor.

[0088] FIG16 is a cogging torque diagram of a coreless motor without a protective cover in the prior art; FIG17 is a torque diagram of a coreless motor with a protective cover in an embodiment of the present invention.

[0089] Please refer to Figure 16 and Figure 17, where the horizontal axis represents the rotation angle and the vertical axis represents the cogging torque. The cogging torque of the hollow cup motor with a protective cover is 0.03mN, and the cogging torque of the hollow cup motor without a protective cover is 0.9mN. It can be seen that the cogging torque of the hollow cup motor with a protective cover is significantly reduced.

[0090] The coreless motor with a protective sleeve can effectively filter the time and space harmonics in the stator magnetic field, reduce the eddy current loss on the rotor surface, reduce the heat generation of the rotor, and improve the efficiency of the motor.

[0091] In summary, the hollow cup motor with a protective cover and the potting method thereof of the present invention adopt a protective cover to protect the stator assembly 4 and the rotor assembly 3, and form a packaging layer by dripping glue at the end to achieve sealing and isolation, thereby realizing reliable protection of the non-biocompatible materials of the motor; especially when water enters the inside of the motor, the packaging layer is not easy to fall off under the water pressure flushing, and the reliability is high.

[0092] Furthermore, the protective cover of the present invention is made of metal sheet, usually titanium alloy. Titanium alloy has good biocompatibility, high strength and stable structure, which is conducive to providing stable and reliable protection. Titanium alloy has low electrical conductivity, effectively filters the time and space harmonics in the stator magnetic field, reduces eddy current loss on the rotor surface, reduces the heat generation of the rotor, improves the efficiency of the motor, and ensures the safety of the motor operation; the welding process is simple and easy to manufacture, and the small thickness of the metal sheet will not affect the overall size of the motor.

[0093] Furthermore, the protective cover of the present invention extends out from both ends of the magnetic steel 32 of the stator assembly 4 or the rotor assembly 3 to form a potting space, which is conducive to drip irrigation of the packaging layer to achieve sealing, while preventing the packaging layer from falling off due to vibration during motor operation.

[0094] Finally, it should be noted that the axial direction, radial direction and circumferential direction in the embodiment of the present invention respectively represent the axial direction, radial direction and circumferential direction of the rotor assembly 3 .

[0095] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present disclosure, even when only a single embodiment is described with respect to specific features. The feature examples provided in the present disclosure are intended to be illustrative, not limiting, unless otherwise stated. In specific implementations, the technical features of one or more dependent claims may be combined with the technical features of the independent claims, depending on actual needs and where technically feasible, and the technical features from the corresponding independent claims may be combined in any appropriate manner rather than solely through the specific combinations listed in the claims.

[0096] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A coreless motor with a protective sleeve, comprising a stator assembly, a rotor assembly, and a housing; the stator assembly is disposed in the housing, the rotor assembly is provided with an axially extending cavity, and the rotor assembly is rotatably disposed in the cavity, characterized in that: The housing is sleeved on the outer wall of the stator assembly and two ends of the housing extend axially out of the two ends of the stator assembly. The inner wall of the stator assembly is provided with a stator protective sleeve. The two ends of the stator protective sleeve extend axially out of the two ends of the stator assembly. The two ends of the stator assembly are provided with a stator packaging layer. The stator protective sleeve, the housing and the stator packaging layer isolate and seal the stator assembly; the rotor assembly includes a magnet and a shaft core. The shaft core is provided at the center of the magnet. The outer wall of the magnet is provided with a rotor protective sleeve. The two ends of the rotor protective sleeve extend axially out of the two ends of the magnet. The ends of the magnet are provided with a rotor packaging layer. The rotor protective sleeve and the rotor packaging layer isolate and seal the magnet.

2. The coreless motor with a protective cover according to claim 1, wherein: The stator protection cover and the rotor protection cover are both made of biocompatible metal materials, and the biocompatible metal materials include stainless steel 316, stainless steel 317, titanium alloy, cobalt alloy, gold, silver, platinum and memory metal.

3. The coreless motor with a protective cover according to claim 2, wherein: The stator protection cover and the rotor protection cover are both cylindrical tube structures, and are both welded by metal sheets made of the biocompatible metal material. The thickness of the metal sheets is 0.01mm-0.05mm.

4. The coreless motor with a protective cover according to claim 1, wherein: The stator packaging layer and the rotor packaging layer are both formed by glue potting.

5. The coreless motor with a protective cover according to claim 1, wherein: The outer diameter of the stator protective cover is smaller than the inner diameter of the stator assembly. The minimum difference between the outer diameter of the stator protective cover and the inner diameter of the stator assembly is 0.02 mm. The stator protective cover and the stator assembly are coaxially arranged so that the minimum gap formed between the stator protective cover and the stator assembly is 0.01 mm. The stator protective cover and the stator assembly are bonded by glue applied to the outer wall of the stator protective cover.

6. The coreless motor with a protective cover according to claim 1, wherein: The difference between the length of the stator protective cover and the length of the stator assembly is 1mm-2mm; the distance between the end of the stator protective cover and the end of the stator assembly at the same end is 0.5mm-1mm, and the stator encapsulation layer is arranged between the end of the stator protective cover and the end of the stator assembly at the same end.

7. The coreless motor with a protective cover according to claim 1, wherein: The inner diameter of the rotor protection cover is larger than the outer diameter of the magnetic steel. The minimum difference between the inner diameter of the rotor protection cover and the outer diameter of the magnetic steel is 0.02 mm. The inner diameter of the rotor protection cover is coaxially arranged with the magnetic steel, so that the minimum gap formed between the rotor protection cover and the magnetic steel is 0.01 mm. The rotor protection cover and the magnetic steel are bonded by glue coated on the inner wall of the rotor protection cover.

8. The coreless motor with a protective cover according to claim 1, wherein: The difference between the length of the rotor protective cover and the length of the magnetic steel is 1mm-2mm; the distance between the end of the rotor protective cover and the end of the magnetic steel at the same end is 0.5mm-1mm, and the rotor encapsulation layer is arranged between the end of the rotor protective cover and the end of the magnetic steel at the same end.

9. The coreless motor with a protective cover according to claim 1, wherein: The outer diameter of the stator assembly is equal to the inner diameter of the housing, and the stator assembly is connected to the housing with a clearance fit.

10. A potting method for a coreless motor with a protective sleeve according to claims 1-9, wherein the coreless motor with a protective sleeve comprises a stator assembly, a rotor assembly, and a housing; the stator assembly is disposed in the housing and has a cavity extending axially therethrough, the rotor assembly is rotatably disposed in the cavity, the rotor assembly comprises a magnet and an axis core, the axis core being disposed through the center of the magnet, wherein: The steps include: Providing the stator assembly and the stator protective sleeve, sleeve-mounting the stator protective sleeve on the inner wall of the stator assembly, and controlling the two ends of the stator protective sleeve to extend axially beyond the two ends of the stator assembly, and the two ends of the stator protective sleeve are equidistant from the two ends of the stator assembly in the axial direction; Provide the housing, and sleeve the housing on the outer wall of the stator assembly installed with the stator protective cover, and control the two ends of the housing to extend axially beyond the two ends of the stator assembly, and the outer wall of the stator protective cover, the inner wall of the housing, the end face of the stator assembly and the stator protective cover are in contact with each other. A stator potting space is formed between the sleeve end faces; dripping glue into the stator potting space to form a stator packaging layer to isolate and seal the stator assembly; Provide the rotor assembly and the rotor protective cover, and sleeve the rotor protective cover over the outer wall of the magnetic steel. Control the two ends of the rotor protective cover to extend axially beyond the two ends of the magnetic steel, and keep the two ends of the rotor protective cover equidistant from the two ends of the magnetic steel in the axial direction. A rotor potting space is formed between the outer wall of the shaft core, the inner wall of the rotor protective cover, the end surface of the magnetic steel, and the end surface of the rotor protective cover. Glue is dripped into the rotor potting space to form a rotor packaging layer to isolate and seal the magnetic steel.

11. The potting method of the coreless motor with a protective cover according to claim 10, characterized in that: The outer diameter of the stator protective cover is smaller than the inner diameter of the stator assembly. The stator protective cover and the stator assembly are coaxially arranged, so that the minimum difference between the outer diameter of the stator protective cover and the inner diameter of the stator assembly is 0.02 mm, and the minimum gap formed between the stator protective cover and the stator assembly is 0.01 mm. The potting method comprises the following steps: Apply glue on the outer wall of the stator protective sleeve, The stator protection sleeve is sleeved on the inner wall of the stator assembly so that the stator protection sleeve and the stator assembly are bonded together as a whole.

12. The potting method of the coreless motor with a protective cover according to claim 10, characterized in that: The inner diameter of the rotor protective cover is larger than the outer diameter of the magnetic steel. The minimum difference between the inner diameter of the rotor protective cover and the outer diameter of the magnetic steel is 0.02 mm. The inner diameter of the rotor protective cover is coaxial with the magnetic steel so that the minimum gap between the rotor protective cover and the magnetic steel is 0.01 mm. The potting method comprises the following steps: Apply glue on the inner wall of the rotor protective cover, The rotor protection cover is sleeved on the outer wall of the magnetic steel so that the rotor protection cover and the rotor assembly are bonded together.

Images