CN113765283B

CN113765283B - Miniature permanent magnet motor for liquid cooling pump

Info

Publication number: CN113765283B
Application number: CN202111136890.5A
Authority: CN
Inventors: 李吉兴; 李玉涛; 曹宽; 韩凯; 郭宇帆; 张丽娟
Original assignee: Xian Aerospace Precision Electromechanical Institute
Current assignee: Xian Aerospace Precision Electromechanical Institute
Priority date: 2021-09-27
Filing date: 2021-09-27
Publication date: 2023-01-10
Anticipated expiration: 2041-09-27
Also published as: CN113765283A

Abstract

The invention particularly relates to a miniature permanent magnet motor for a liquid cooling pump, which solves the structural design problems of large friction loss, large mechanical clearance, low efficiency, insufficient structural strength and weak resistance of radial impact force of a traditional miniature liquid cooling pump motor sealing piece. A miniature permanent magnet motor for a liquid cooling pump comprises an end cover assembly, a shell, a stator assembly and a rotor assembly; the end cover assembly and the shell are fixedly and hermetically connected to form a stator and rotor mounting cavity; the stator component is positioned in the stator and rotor mounting cavity and comprises a stator sheath and a stator armature which are coaxially arranged from inside to outside in sequence; the rotor assembly comprises a motor shaft, and a rotor core, magnetic steel and a rotor sheath which are positioned in the stator and rotor mounting cavity and coaxially arranged on the motor shaft from inside to outside in sequence; according to the invention, the end cover assembly is provided with the first flow channel, the rear bushing is provided with the second flow channel, the motor shaft is internally provided with the third flow channel, and the three flow channels are matched with the gap for use, so that the flow resistance of cooling liquid in the motor is reduced, and the motor efficiency is improved.

Description

Miniature permanent magnet motor for liquid cooling pump

Technical Field

The invention belongs to the technical field of motors, and particularly relates to a miniature permanent magnet motor for a liquid cooling pump.

Background

With the progress of aerospace technology, the liquid cooling pump technology is widely applied, and the permanent magnet motor serves as an important component of the liquid cooling pump system and provides power for the liquid cooling pump. The structure design that the output shaft stretches out the dynamic seal is adopted in the traditional permanent magnet motor structure, and the cooling liquid is prevented from entering the motor.

The permanent magnet motor of the existing liquid cooling pump adopts a structure that cooling liquid circulates in a cavity inside an immersion motor. The structure has overlarge flow resistance and unreasonable flow passage opening positions, and easily causes the problems of leakage of cooling liquid and uneven cooling.

The stator sheath is generally made of metal or nonmetal materials, and when the stator sheath is made of metal, the structural strength is good, but because the stator sheath has an eddy current effect, when the rotating speed of the permanent magnet motor is too high, the eddy current loss is too large, and the loss can account for 15% -30% of the total power.

When the stator sheath is manufactured in a non-metal mode, no eddy current effect exists, but the structural strength is insufficient, the mechanical gap is too large, the gap magnetic density of the permanent magnet motor is low, the material utilization rate is low, the motor is large in size and weight, resistance to radial impact force is weak, and the efficiency of the permanent magnet motor is low.

In addition, the permanent magnet motor bearing with the structure is generally a graphite bearing, the graphite bearing needs cooling liquid lubrication when in work, when the cooling liquid in a liquid cooling pump system is insufficient, the graphite bearing cannot work at a high speed, and carbon powder is produced in the rotating process to pollute the cooling liquid.

Meanwhile, due to the limitations of space, total amount and the like of aerospace products, a permanent magnet motor with small volume and light weight is generally required to be selected, and the permanent magnet motor is required to have reliable work, impact resistance and high efficiency, so that the permanent magnet motor of the liquid cooling pump with larger volume at present can not meet the use requirement.

Disclosure of Invention

The miniature permanent magnet motor for the liquid cooling pump solves the structural design problems of unreasonable flow passage arrangement, insufficient structural strength and weak resistance to radial impact force of the traditional miniature liquid cooling pump motor.

The technical solution of the invention is as follows:

a miniature permanent magnet motor for a liquid cooling pump comprises an end cover assembly, a shell, a stator assembly and a rotor assembly;

the end cap assembly includes an end cap and a front bushing;

the end cover and the shell are fixedly, hermetically and fixedly connected to form a stator and rotor mounting cavity;

the stator assembly is positioned in the stator and rotor mounting cavity and comprises a stator sheath and a stator armature which are coaxially arranged from inside to outside in sequence; the stator assembly also comprises a rear bushing which is positioned at the tail part of the machine shell;

the rotor assembly comprises a motor shaft, a rotor iron core, magnetic steel and a rotor sheath, wherein the rotor iron core, the magnetic steel and the rotor sheath are positioned in the stator and rotor mounting cavity and coaxially arranged on the motor shaft from inside to outside in sequence;

the front end of the motor shaft is supported on the end cover assembly through a front bearing arranged in the front bushing and extends to the outside, and the rear end of the motor shaft is supported on the inner wall of the rear end of the shell through a rear bearing arranged in the rear bushing;

an annular gap is formed between the rotor sheath and the stator sheath;

it is characterized in that:

a plurality of first flow passages are arranged on the end cover assembly and communicated with the annular gap; a plurality of second flow passages are arranged on the rear bushing;

a third flow channel is arranged in the motor shaft along the axial direction;

and the cooling liquid flows into the annular gap through the first flow channels and flows out of the third flow channels through the second flow channels, so that the circulating cooling is realized.

Furthermore, two cavities are respectively formed among the front end of the stator armature, the front end in the shell and the end cover, as well as the rear end of the stator assembly and the rear end in the shell, and the two cavities are filled with sealant;

the stator sheath is made of a non-metal material, one end of the stator sheath is embedded into the rear end of the shell, and the part of the stator sheath embedded into the shell is thickened; the other end of the stator sheath is close to the end cover component;

the sealant, the end cap assembly and the casing together form a support structure for the stator sheath.

Further, the front bushing and the rear bushing are consistent in structure;

the inner walls of the front bushing and the rear bushing are respectively formed by a plurality of planes and a plurality of arc surfaces in an alternating mode and are used for forming a limiting structure for mounting the bearing;

the number of planes and arc surfaces forming the inner wall of the front bushing is consistent with the number of the first flow channels;

the number of the planes and the arc surfaces forming the inner wall of the rear bushing is consistent with that of the second flow passages.

Further, the front bearing and the rear bearing are both special-shaped ceramic ball bearings.

Furthermore, the rotor assembly further comprises a balance ring, the balance ring is sleeved on the motor shaft, two ends of the rotor sheath are provided with the balance ring, and the balance ring is provided with a plurality of conical grooves.

Further, the stator armature is installed through the front end of the machine shell to form a stator armature front-installation structure.

Further, the diameter of the third flow channel inside the stator and rotor installation cavity is larger than that of the other part of the third flow channel.

Further, the first flow channel and the second flow channel can be set to be three, four, five, six or seven, the more the number of the flow channels is set, the more the oil storage amount is, but the more complex the processing is.

Compared with the prior art, the invention has the beneficial effects that:

(1) In the invention, the end cover, the rear bushing and the motor shaft are provided with the first flow passages, the second flow passages and the third flow passages to form the circulating cooling flow passages of the motor, and the passages can reduce the flow resistance, effectively reduce the weight of the motor and improve the efficiency of the motor when in use.

(2) In the invention, the stator sheath is contacted with the cooling liquid and the sealant; the stator sheath extends towards the rear end of the interior of the shell and extends to be close to the shell, and the rear end of the stator sheath is thickened to strengthen the radial impact resistance of the motor; the stator boot extends toward the front interior of the housing and extends to abut the end cap assembly. The motor has the advantages that the size of the motor is reduced, the air gap length of the motor is reduced, the magnetic load of the motor is improved, and the efficiency of the motor is increased. When the motor works, the stator sheath is supported by the two sides to bear larger radial impact.

(3) The front bearing and the rear bearing are both special-shaped ceramic ball bearings, and the arrangement reduces the axial space of the bearings, thereby reducing the axial length of the motor, and having small bearing loss and light weight; the special-shaped structure is matched with the front and rear bushing supporting structures, so that relative rotary motion between the bearing outer ring and the bushing is avoided; when the cooling liquid is insufficient or an experimental test is carried out by using a water medium, self-lubrication can be realized, and the motor can rotate without generating impurities to pollute the cooling liquid.

(4) According to the invention, the inner walls of the front bushing and the rear bushing are provided with the bearing limiting structures alternately formed by a plurality of planes and a plurality of arc surfaces, and the bearing limiting structures are matched with the special-shaped ceramic ball bearings, so that the relative rotation motion between the bearing outer ring and the bushing is avoided.

(5) The balancing ring is provided with the tapered groove, so that the precision level of dynamic balance of the micro rotor assembly can be improved, and the rotor assembly can stably rotate at a high speed.

(6) The stator armature front-mounted structure is structurally designed, the stator armature and the wire outlet hole in the shell are sealed together, effective sealing of the wire outlet position of the motor is achieved, the stator assembly and the end cover assembly are fixedly connected in a welding mode, axial space for screw connection is saved, the welding position on the structural design is staggered with the position of the O-shaped ring, the O-shaped ring is prevented from being burnt out due to local overheating caused by welding, and the end face of the end cover assembly on the structural design is higher than the front end face of the shell; when the motor is matched with the pump, the end surface of the end cover assembly is stressed, when the motor bears large axial impact, the welding position is not stressed, and the motor can bear large axial impact.

(7) Compared with the traditional graphite sliding bearing, the ceramic ball bearing support structure has the advantages that the bearing is small in size and light in weight, can achieve a self-lubricating effect when the flow of a cooling liquid medium is insufficient or a water test is carried out, and is high in reliability; secondly, the bearing loss is small in the working state, and impurities cannot be generated in the running process to pollute the cooling liquid; the motor is ensured to work reliably under the environment of load, overload and vibration impact.

Drawings

FIG. 1 is a schematic view of the motor structure of the present invention;

FIG. 2 is a schematic three-dimensional view of the end cap assembly of the present invention;

FIG. 3 is a schematic axial cross-sectional view of an end cap assembly of the present invention;

FIG. 4 is a schematic view of the front bushing structure of the present invention;

FIG. 5 is a schematic view of a stator assembly of the present invention;

FIG. 6 is a schematic three-dimensional view of the rear bushing of the present invention;

FIG. 7 is a schematic view of a rotor assembly according to the present invention;

FIG. 8 isbase:Sub>A cross-sectional view A-A of the rotor assembly structure of FIG. 7;

FIG. 9 is a schematic view of a rotor core structure according to the present invention;

fig. 10 is a schematic view of a balanced ring structure according to the present invention.

The reference numerals are specifically as follows:

1. the motor comprises an end cover assembly, a front bearing 2, a 3.O ring, a stator assembly 4, a rotor assembly 5, a rear bearing 6, an annular gap 7, an outlet hole 8, an end cover 11, a front bushing 12, a sealant 41, a stator sheath 642, a stator armature 43, a stator armature 44, a rear bushing 45, a machine shell 51, a motor shaft 52, a balance ring 53, a rotor iron core 54, magnetic steel 55 and a rotor sheath.

Detailed Description

The invention is further illustrated and described with reference to the following figures and detailed description.

The micro permanent magnet motor for the liquid cooling pump has the advantages that the outer diameter of the motor is 8mm, the motor efficiency can reach 95%, and the rated rotating speed of the motor is 16000r/min. As shown in fig. 1: the motor comprises an end cover assembly 1, a machine shell 45, a stator assembly 4 and a rotor assembly 5, wherein the end cover assembly 1 and the machine shell 45 are fixedly sealed to form a stator and rotor installation cavity of the stator assembly 4 and the rotor assembly 5. In deciding the rotor installation intracavity, rotor subassembly 5 is connected with end cover subassembly 1 through front bearing 2, and rotor subassembly 5 is connected with stator module 4 through rear bearing 6, and rear bearing 6 is located the 45 afterbody of casing, and stator module 4 is located the inside both sides of casing 45 on the surface, carries out static seal through O type circle 3 between stator module 4 and the end cover subassembly 1, and the casing afterbody still is provided with wire hole 8.

In the invention, the front bearing 2 and the rear bearing 6 both adopt special-shaped ceramic ball bearings. Compared with the traditional graphite sliding bearing, the special-shaped ceramic ball bearing has the advantages that the special-shaped ceramic ball bearing is small in axial length, small in size and light in weight, can realize a self-lubricating effect when the flow of a cooling liquid medium is insufficient or a test medium is replaced by a water test, namely the test medium is replaced at low cost, and is high in reliability; secondly, the bearing loss is small under the working state, and impurities can not be generated in the running process to pollute the cooling liquid. Through calculation of load and fatigue life of the bearing, the thickness of the front bearing 2 is 3mm, the thickness of the rear bearing 6 is 2.5mm, and the size design can ensure that the motor can reliably work under the environments of load, overload and vibration impact and can also ensure that the bearing loss of the motor is minimum under the working state.

As shown in fig. 2 and 3: the end assembly comprises an end cover 11 and a front bushing 12, the end cover 11 and the front bushing 12 are in interference fit, a sealing groove and five first flow passages are designed on the end cover 11, and the first flow passages can also be arranged on the outer ring surface of the front bushing 12 matched with the end cover 11 or the inner surface of the front bushing 12; the cross section of the first flow channel is semicircular, the flow cross section of the flow channel is 7L-shaped, and the shape is easy to process. The cross section of the first flow passage can also be square or rectangular, and the cross section is larger than that of a semicircle, so that more cooling liquid can be stored, but the processing is complicated; the flow passage cross section can also be a spiral type, and compared with the L-shaped cross section, the flow passage cross section can store more cooling liquid, but the processing is complex and the price is high. The five first flow channels are matched with other flow channel parts in the motor for use, so that the minimum flow resistance of the motor is ensured.

Front bushing 12 is as shown in fig. 4, and front bushing 12 inner wall is provided with the limit structure who supports spacing front bearing 2, and limit structure constitutes for plane and arc surface cycle in turn, and plane quantity equals the quantity that arc surface quantity equals first flow channel, and front bushing 12 internal surface and front bearing 2 clearance fit for when the motor is high-speed rotatory, bearing inner race atress is even, can not produce radial relative motion with front bushing 12, has avoided the loss that bearing inner race and front bushing 12 radial relative motion arouse.

As shown in fig. 5, the stator assembly 4 includes a stator sheath 42, a stator armature 43, and a rear liner 44. The stator assembly is sequentially and coaxially provided with a stator sheath 42 and a stator armature 43 from inside to outside, the stator armature 43 is attached to the inner surface of the machine shell 45, and the stator armature 43 is assembled from the front end of the machine shell 45 to form a stator armature front-assembled structure; the rear bushing 44 is located at the tail of the casing 45 and is in interference fit with the casing, and the rear bushing 44 is connected with the rear bearing 6. The cavity among the stator sheath 42, the stator armature 43, the machine shell 45 and the end cover assembly 1 is sealed by the sealant 41, the stator armature 43 and the wire outlet hole 8 are sealed together by the sealant 41, the sealant 41 prevents the cooling liquid from contacting with the stator armature 43, and can support the stator sheath 42 and reduce the thickness of the stator sheath 42. As shown in fig. 6, the number of the inner surface limiting surfaces of the rear bushing 44 is consistent with that of the second flow passages, and the effect of the rear bushing is consistent with that of the front bushing 12; the rear bushing 44 is designed with 5 second flow channels, and the second flow channels are matched with the rest flow channels to ensure the minimum flow resistance.

The stator armature front-loading structure is such that the stator armature 43 is loaded through the front end of the housing 45. Make welding position and O type circle 3 position on the casing 45 stagger, avoid the local overheat that end cover subassembly 1 and casing 45 welding arouse to burn out

O type circle

3, 1 terminal surface 8 of structure upper end cover subassembly is higher than the 4 terminal surfaces of stator module. When the shell 45 is matched with the liquid cooling pump, the end face of the end cover assembly 1 is stressed, when the motor bears large axial impact, the welding position is not stressed, and the motor can bear large axial impact.

The stator sheath 42 is made of a non-metal material, and two sides of the stator sheath 42 are in contact with cooling liquid or sealant; one end of the stator sheath 42 is embedded into the rear end of the casing 45, and the rear end of the stator sheath 42 embedded into the casing 45 is thickened to be matched with a bearing chamber for supporting the rear bearing 6; the other end of the stator sheath 42 extends to be in close proximity to the end cap assembly 1; when the motor works, the stator sheath 42 can bear larger radial impact supported by two sides, so the thickness can be designed to be thinner. The structural design reduces the electric clearance of the motor, reduces the volume of the motor, improves the magnetic load of the motor and increases the efficiency of the motor.

As shown in fig. 7 and 8, the rotor assembly 5 includes a motor shaft 51, a balance ring 52, a rotor core 53, magnetic steel 54, and a rotor sheath 55. With a motor shaft 51 as an axis, a rotor core 53, a magnetic steel 54, and a rotor sheath 55 are sequentially sleeved from the inside to the outside. The rotor core 53 is a regular hexagonal prism with an axial through hole, six side faces of the rotor core 53 are respectively provided with a magnetic steel 54 with the same area as the side faces, the rotor sheath 55 is a circular column, and the rotor sheath 55 is sleeved on the outer surface of the magnetic steel 54. The motor shaft 51 is also sleeved with a balance ring 52 on the side, and the balance ring 52 is in contact with both side ends of the rotor core 53, the magnetic steel 54 and the rotor sheath 55. The balance ring 52 is used for realizing dynamic balance when the rotor assembly 5 rotates at a high speed; as shown in fig. 9, the outer surface of the rotor core 53 is provided with a glue storage groove, and the glue storage groove is used for fixing the magnetic steel 54; the rotor sheath 55 serves to protect the magnetic steel 54 from contact corrosion by the coolant. The balance ring 52, the motor shaft 51 and the rotor sheath 55 are sealed by welding, and the cavity between the rotor sheath 55 and the magnetic steel 54 and the rotor core 53 is sealed by glue.

The motor shaft 51 is provided with a third flow passage inside, the third flow passage is of a sectional structure, and flow passage holes are opened in sections according to the axial outer diameter of the motor shaft 51, and the diameters of the two flow passage holes are different. The axial section of the third flow passage is in a spiral shape, the structure is suitable for overload of the flow of the cooling liquid caused by unstable working conditions 9, but the structure is complex to process and expensive.

The third flow channel structure reduces the flow resistance of the cooling liquid, effectively reduces the weight of the motor and reduces the rotational inertia of the rotor assembly 5.

As shown in fig. 10, the balance ring 52 is provided with a plurality of tapered grooves uniformly distributed, when the amount of unbalance is determined, the weight of the solder can be weighed, and the solder is heated and added into the corresponding tapered grooves, so that the precision level of the dynamic balance of the micro rotor assembly 5 can be improved, and the high-speed stable rotation of the permanent magnet motor 16000r/min can be realized.

In the invention, the shape of the special-shaped ceramic ball bearing outer ring is consistent with the shape and the structure of the front bushing 12 and the rear bushing 44, and the special-shaped ceramic ball bearing outer ring and the front bushing can be matched with each other, so that the bearing outer ring and the bushings are prevented from generating relative rotation motion. The inner ring of the front bearing 2 is matched with the front end installation position of the motor shaft 51, the outer ring of the front bearing 2 is in clearance fit with the inner surface of the front bushing 12, the inner ring of the rear bearing 6 is matched with the rear end installation position of the motor shaft 51, and the outer ring of the rear bearing 6 is in clearance fit with the inner surface of the rear bushing 44.

The coolant medium flows in from the gap between the end cover assembly 1 and the motor shaft 51, flows through the first flow channel, the annular gap 7 between the stator assembly 4 and the rotor assembly 5, the second flow channel and the third flow channel, and flows out from the shaft extension end of the motor shaft 51, and the flow path of the flow channel is shown in fig. 1. The thickness of a mechanical gap structure of the motor is designed to be 0.356mm and the thickness of an electrical gap structure is designed to be 0.75mm under the limitation of volume, and through fluid simulation, the structural design can reduce the volume and the weight of the motor, increase the magnetic load of the motor and improve the high-efficiency performance of the motor; and the flow resistance is minimum, the flow loss of the cooling liquid medium is minimum, and the high-efficiency performance of the motor is ensured.

Claims

1. A miniature permanent magnet motor for a liquid cooling pump comprises an end cover assembly (1), a shell (45), a stator assembly (4) and a rotor assembly (5);

the end cover assembly (1) comprises an end cover (11) and a front bushing (12);

the end cover (11) and the shell (45) are fixedly, hermetically and fixedly connected to form a stator and rotor mounting cavity;

the stator assembly (4) is positioned in the stator and rotor mounting cavity and comprises a stator sheath (42) and a stator armature (43) which are coaxially arranged from inside to outside in sequence; the stator assembly (4) also comprises a rear bushing (44), and the rear bushing (44) is positioned at the tail part of the machine shell (45);

the rotor assembly (5) comprises a motor shaft (51), a rotor iron core (53), magnetic steel (54) and a rotor sheath (55), wherein the rotor iron core (53) is positioned in the stator and rotor mounting cavity and sequentially and coaxially arranged on the motor shaft (51) from inside to outside;

the front end of the motor shaft (51) is supported on the end cover assembly (1) through a front bearing (2) arranged in the front bushing (12) and extends to the outside, and the rear end of the motor shaft (51) is supported on the inner wall of the rear end of the shell (45) through a rear bearing (6) arranged in the rear bushing (44);

an annular gap (7) exists between the rotor sheath (55) and the stator sheath (42);

the method is characterized in that:

a plurality of first flow channels are arranged on the end cover assembly (1), the first flow channels are communicated with the annular gap, and the flow cross section of each first flow channel is spiral;

a plurality of second flow passages are arranged on the rear bushing (44);

a third flow channel is axially arranged in the motor shaft (51), and the flow section of the third flow channel is spiral;

the cooling liquid flows into the annular gap through the first flow channels and flows out of the third flow channels through the second flow channels, so that circulating cooling is realized;

two cavities are formed among the front end of the stator armature (43), the stator sheath (42), the front end inside the machine shell (45) and the end cover (11), and the rear end of the stator assembly (4), the rear end inside the stator sheath (42) and the rear end inside the machine shell (45), and the two cavities are filled with sealant (41);

the stator sheath (42) is made of a non-metal material, one end of the stator sheath (42) is embedded into the rear end of the shell (45), and the part of the stator sheath (42) embedded into the shell (45) is thickened; the other end of the stator sheath (42) is close to the end cover component (1);

the sealant (41), the end cover assembly (1) and the shell (45) jointly form a supporting structure of the stator sheath (42);

the front bushing (12) and the rear bushing (44) are consistent in structure;

the inner walls of the front bushing (12) and the rear bushing (44) are respectively formed by a plurality of planes and a plurality of arc surfaces in an alternating mode and are used for forming a limiting structure for mounting a bearing;

the number of the planes and the arc surfaces forming the inner wall of the front bushing (12) is consistent with that of the first flow passages;

the number of planes and arc surfaces forming the inner wall of the rear bushing (44) is the same as the number of the second flow passages.

2. The miniature permanent magnet motor for the liquid-cooled pump according to claim 1, wherein: the front bearing (2) and the rear bearing (6) are both special-shaped ceramic ball bearings.

3. The miniature permanent magnet motor for the liquid-cooled pump according to claim 1, wherein: the rotor assembly (5) further comprises a balance ring (52), the balance ring (52) is sleeved on the motor shaft (51), two ends of the rotor sheath (55) are provided with the balance ring (52), and a plurality of conical grooves are formed in the balance ring (52).

4. The miniature permanent magnet motor for the liquid cooling pump according to claim 1, wherein: the stator armature (43) is installed through the front end of the casing (45) to form a stator armature front-installation structure.

5. The miniature permanent magnet motor for the liquid-cooled pump according to claim 4, wherein: the diameter of the third flow channel positioned in the stator and rotor mounting cavity is larger than that of the other part of the third flow channel.

6. The miniature permanent magnet motor for the liquid-cooled pump according to claim 1, wherein: the number of the first flow passages and the number of the second flow passages can be three, four, five, six or seven.