CN218829290U - Permanent magnet rotor of low-power motor and electric water pump - Google Patents

Abstract

The utility model provides a permanent magnet rotor of miniwatt motor, include: permanent magnet and the portion of moulding plastics, the permanent magnet is the cylinder that the diameter is D, and oval-shaped connecting hole has been seted up to its middle part axial, the portion of moulding plastics uses the permanent magnet as the basis injection moulding, the permanent magnet is in its terminal surface around connecting hole circumference interval ground is provided with a plurality of recessed recesses of axial concave, the portion of moulding plastics cladding connecting hole, recess and terminal surface are whole or partly, the portion center of moulding plastics is equipped with a diameter and is D cylindrical shaft hole, then has: d =15mm-23mm, D/D =15% -25%. The ratio of the diameter d of the shaft hole of the injection molding part to the diameter of the permanent magnet is set, so that slight separation and dislocation of the injection molding part and the permanent magnet are avoided. The utility model also provides an electric water pump, including pivot, impeller and foretell permanent magnet rotor, permanent magnet rotor's shaft hole cover is located can drive in the pivot and impeller are rotatory together.

Description

Permanent magnet rotor of low-power motor and electric water pump

Technical Field

The utility model belongs to permanent magnet rotor preparation field especially relates to a permanent magnet rotor of miniwatt motor and applied this permanent magnet rotor's electric water pump, and IPC is categorised belongs to H02K1/27.

Background

The existing permanent magnet rotor, such as a permanent magnet rotor disclosed in chinese patent publication CN214314747U, includes a magnet and a rotating shaft, wherein the rotating shaft passes through an axial connecting hole of the magnet; the magnet and the rotating shaft are connected through an injection molding piece. The injection molding piece is obtained by adopting an injection molding mode, and the injection molding piece is integrally injection molded on the basis of the magnet and the rotating shaft; the injection molding piece comprises a first part, a second part and a third part, wherein the first part is a filling space between the rotating shaft and the axial connecting hole, the second part is a filling space of a tooth groove in the end face of the magnet and/or a filling space in a sunken step, the third part is a filling space from the tooth groove to the end face of the injection molding piece, and the third part is used for covering the end plane of the magnet. The injection molding part is used for transmitting power between the rotating shaft and the magnet, but after long-term operation, noise often appears when the permanent magnet rotor is started.

The common knowledge and terms can be found in the mechanical engineering handbook 2 edition and the motor engineering handbook 1997 of mechanical industry publishers, the pump theory and technology 1 edition of mechanical industry publishers 2014, the national standard GB/T7021 noun terms of centrifugal pumps, the AC permanent magnet drainage pump starting mechanism in Chinese patent CN203500035U, and the transmission device between the rotor and the working component of the permanent magnet synchronous motor in Chinese patent CN 101408228B.

Disclosure of Invention

The utility model discloses inventor's experiment discovers prior art's permanent magnet rotor after long-term operation, slight separation dislocation appears between magnetic core and the injection molding contact layer, and when positive and negative rotation starts, they strike each other, and the noise is sent. For solving above-mentioned problem, to the permanent magnet of different diameters, because the electromagnetic torque that it provided is different, can optimize the contact layer area of magnetic core and injection molding structure, magnetic core and injection molding contact layer, the thickness isoparametric of contact layer, specifically as follows:

the utility model provides a permanent magnet rotor of miniwatt motor, include: permanent magnet and the portion of moulding plastics, the permanent magnet is the cylinder that the diameter is D, and oval-shaped connecting hole has been seted up to its middle part axial, the portion of moulding plastics uses the permanent magnet as basis injection moulding, the permanent magnet centers on its terminal surface the connecting hole circumference interval is provided with 2 above along the recessed concave part of axial, the portion cladding of moulding plastics connecting hole, concave part and terminal surface are whole or partly to fill the concave part and form a plurality of connecting portions, the portion center of moulding plastics is equipped with one and supplies the rotor shaft of motor passes through and the cylindrical shaft hole that the diameter is D, then has: d =15mm-23mm, D/D =15% -25%.

Aiming at the permanent magnet with a certain diameter range, the combination of the diameter D of the shaft hole of the injection molding part and the diameter D of the permanent magnet is set according to the proportion, so that the strength of the transmission of electromagnetic torque of the rotating shaft contained in the shaft hole can be ensured, the large contact area between the injection molding part and the permanent magnet can be further limited, and the injection molding part and the permanent magnet are prevented from being slightly separated and dislocated to cause the mutual impact and generate noise when the forward and reverse rotation is started.

Further, the major diameter of the oval connecting hole is a, and the minor diameter is b, then there are: 0.6mm to (a-b) to 1.5mm and 1.5mm to (b-d) to 3mm.

According to experimental verification, by setting the difference range of the long diameter and the short diameter of the connecting hole and the minimum thickness of the short diameter, the strength of the connecting hole-coated pipe body of the injection molding part for transmitting electromagnetic torque can be guaranteed, the larger contact area between the pipe body and the permanent magnet can be further strengthened and limited, the connection strength of the pipe body and the permanent magnet can be guaranteed, and the phenomenon that the injection molding part and the permanent magnet are slightly separated and dislocated to cause the pipe body and the permanent magnet to mutually impact and generate noise when the forward and reverse rotation is started can be avoided.

Furthermore, the end face of the permanent magnet is provided with a conical surface inclined towards the inner wall of the connecting hole around the connecting hole, the concave part comprises a first end and a second end, the first end is communicated with the conical surface, and the second end extends along the end face in the radial direction to leave the first end for a certain distance.

Preferably, the number of the recesses is not less than 4

Preferably, the width of the first end is less than the width of the second end.

Preferably, the width of the first end is equal to the width of the second end.

The arrangement of the conical surface increases the thickness of the injection molding part in the axial direction of the part covering the conical surface, prevents the permanent magnet inside from being directly exposed after the plastic of the part is stripped by collision in production and use, and leads the permanent magnet to be easily corroded.

The arrangement of the recesses and the number thereof are set to 4 or more so that the recesses are closely distributed at the end face. Generally, the connecting portion is loosened from the recess portion due to a clearance between the connecting portion and the recess portion after being shrunk by cooling, thereby generating collision noise during rotation. Under the condition of ensuring that the concave parts have certain structural strength, the more the concave parts are opened, the smaller the space volume occupied by each concave part is, therefore, even if the connecting part formed in the concave part is shrunk by cooling, the shrunk volume of each connecting part is also reduced, the gap between the concave part formed by shrinkage and the connecting part is correspondingly reduced, and the collision noise is effectively reduced.

The utility model also provides an electric water pump, including pivot, impeller and foretell permanent magnet rotor, permanent magnet rotor's shaft hole cover is located in the pivot and can drive pivot and impeller are rotatory together.

Drawings

Fig. 1 is a perspective view of a permanent magnet of the present invention;

fig. 2 is an axial sectional view of the permanent magnet of the present invention;

fig. 3 is a radial cross-sectional view of the permanent magnet of the present invention;

fig. 4 is an axial cross-sectional view of the permanent magnet rotor of the present invention;

fig. 5 is a radial cross-sectional view of the permanent magnet rotor of the present invention;

fig. 6 is a sectional view of an embodiment of the electric water pump of the present invention.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The utility model provides a pair of miniwatt motor's permanent magnet rotor, including permanent magnet 10 and the portion of moulding plastics 30.

As shown in fig. 1 to 3, the permanent magnet 10 is a cylindrical magnetic ring formed by sintering or bonding anisotropic ferrite powder, the diameter of the cylinder is D, an oval connecting hole 11 penetrating through both ends is axially formed in the middle of the permanent magnet 10, the major diameter of the oval is a, and the minor diameter of the oval is b. The end face 12 of the permanent magnet 10 is provided with a conical surface 13 and more than 2 concave parts 14 which are concave along the axial direction around the connecting hole 11, the conical surface 13 inclines towards the inner wall of the connecting hole 11, the concave parts 14 are grooves which are arranged around the connecting hole 11 at equal angular intervals and are concave on the end face 12, each concave part comprises a first end 141 close to the axis of the permanent magnet 10 and a second end 142 away from the axis of the permanent magnet 10, the first end 141 is communicated with the conical surface 13 into a whole, and the second end 142 is radially outwards away from the first end 141 for a certain distance and can be communicated with the conical surface 13 in the axial projection range of the conical surface 13, and preferably communicated with the end face 12 in the axial projection range away from the conical surface 13 as shown in fig. 1. The width of the first end 141 may preferably be designed to be the same as the width of the second end 142, and may also be smaller than the width of the second end 142 to form an inverted shape, thereby enhancing the connection. The number of recesses 14 of the end face 12 may be set to be generally 2, 3, 4, 6, etc.

As shown in fig. 4-5, the injection part 30 is an integral injection structure formed by injecting plastic into the permanent magnet 10 as an insert, wherein the plastic covers the entire inner wall and end 12 of the connection hole 11, including the tapered surface 13 and the concave parts 14, and flows from the first end 141 of each concave part 14 to the second end 142 of the corresponding concave part 14, so as to form a plurality of connection parts 31 and concave parts 14, the number of which is the same as that of the concave parts 14, and are tightly connected with each other. The connection portion 31 circumferentially interferes with the end face 12 so that the injection molded portion 30 and the permanent magnet 10 can rotate synchronously. The injection molding part 30 covers the inner wall of the connecting hole 11 to form a tube, and a circular shaft hole 32 with a diameter d is formed in the center of the tube, and the shaft hole 32 is penetrated by a rotating shaft of the electric water pump so that the permanent magnet rotor can drive or rotate around the rotating shaft. In other embodiments, the plastic of the injection molded part may not cover all of the end portion 12, but must cover the portion including the recess 14.

The present inventors have found that when the number of the concave portions 14 is designed to be large, the concave portions 14 are densely distributed on the end surface 12. Generally, the connecting portion 31 is loosened by a gap between the connecting portion and the recess 14 after being shrunk by cooling, thereby generating collision noise during rotation. Under the condition of ensuring that the concave parts 14 have certain structural strength, the more the concave parts 14 are opened, the smaller the space occupied by each concave part 14 is, therefore, even if the connecting parts 31 formed in the concave parts 14 shrink due to cooling, the shrunk volume of each connecting part 31 is also smaller, the gap between the concave parts 14 and the connecting parts 31 formed by shrinkage is correspondingly smaller, the loosening phenomenon is effectively reduced, and the collision noise generated during rotation is avoided. Therefore, it is preferable that the number of the concave portions 14 is not less than 4, and the concave portions are uniformly arranged in the circumferential direction around the center line of the connecting hole 11.

The utility model discloses inventor's experiment discovers, to the permanent magnet 10 of different diameter D, because the electromagnetic torque that it provided is different, thereby the selection of the circular shaft hole diameter D of the portion of moulding plastics 30 is to avoiding long-term operation back permanent magnet and the portion of moulding plastics not hard up each other and produce collision noise and electric water pump's low pressure start-up performance crucial when starting. Specifically, the utility model discloses the inventor selects a certain permanent magnet rotor to assemble on electric water pump, and the parameter of permanent magnet connecting hole 11 satisfies: the short diameter b = D +2mm, the long diameter a = b +1mm, for different permanent magnet diameters D, the circular shaft hole diameters D of different injection parts are selected for carrying out a start life test (the rated voltage is 220V, the frequency is 50Hz, 5s on and 5s off are a period, the circular operation test is carried out until collision noise occurs in the permanent magnet 10, the collision noise does not occur in more than 30 ten thousand periods, and the start life test is qualified) and a low-voltage start voltage test (the minimum voltage for qualified start can be tested, each voltage test is carried out for 5 times, and the rated rotating speed is reached within 5s every time to be qualified for start), wherein the test data are as follows:

it can be seen from the above test data that, as the (D/D)% is reduced to below 15%, the connection area between the pipe body of the injection part and the permanent magnet is reduced, the injection part and the permanent magnet will slightly loosen after long-term use, and they will collide with each other to generate noise, which cannot meet the requirement of the start-up life test, i.e., (D/D)% needs to be greater than 15%. That is, the ratio of the diameter D of the circular shaft hole of the injection molded part 30 to the diameter D of the permanent magnet 10 is greater than 15%.

In addition, it can be seen that when the (D/D)% is greater than 25%, the volume of the permanent magnet is reduced due to the increase of the pipe body of the injection part, the supplied electromagnetic torque is reduced, and the starting voltage exceeds 187V, that is, the requirement of normal starting at 0.85 times of rated voltage cannot be met. I.e., (D/D)% needs to be less than 25%. That is, the ratio of the diameter D of the circular shaft hole of the injection molded part 30 to the diameter D of the permanent magnet 10 is greater than 25%.

Compare in current design, be equipped with the utility model discloses an electric water pump of permanent magnet rotor possesses good low pressure startability, moreover, can satisfy the start-up life test that is greater than 30 ten thousand cycles, guarantees that electric water pump uses the back for a long time, and not hard up phenomenon can not appear with the permanent magnet in the portion of moulding plastics, does not start the noise of striking each other.

Further, the utility model discloses the inventor has selected the permanent magnet in above-mentioned qualified scope and the different groups of the portion of moulding plastics, the difference of the major diameter a of the connecting hole 11 that changes the permanent magnet and minor diameter b and the difference of minor diameter b and the shaft hole diameter d of the portion of moulding plastics 30, be 220V at rated voltage, the frequency is under 50 Hz's test condition, the start life test has been carried out (5 s stop 5s are a cycle, the cyclic operation test appears the collision noise to permanent magnet 10 and ends, it is qualified for the start life test to be greater than 30 ten thousand cycles collision noise disappearance), test data is as follows:

as can be seen from the above test data, as the difference (a-b) between the major diameter a and the minor diameter b of the connection hole 11 is reduced to 0.6mm

When the difference (b-d) between the short diameter b and the diameter d of the through hole is reduced to be less than 1.5mm, the deformation resistance strength of the pipe body of the injection part is insufficient, the connecting area of the pipe body and the permanent magnet is reduced, the injection part and the permanent magnet are slightly loosened after long-term use, the injection part and the permanent magnet collide with each other to generate noise, and the starting life test requirement cannot be met, namely (a-b) is required to be more than 0.6mm; (b-d) needs to be larger than 1.5mm.

In addition, it can be seen that, when the difference (a-b) between the major diameter a and the minor diameter b of the connecting hole 11 is increased to more than 1.5mm and the difference (b-d) between the minor diameter b and the diameter d of the through hole is increased to more than 3.0mm, the injection molding defect is generated due to the increase of the wall thickness of the pipe body of the injection molding part, so that the pipe body is easy to deform and the connection surface of the pipe body and the permanent magnet is not in good contact, the injection molding part and the permanent magnet are slightly loosened after long-term use, and the injection molding part and the permanent magnet collide with each other to generate noise, so that the start life test requirement cannot be met, namely (a-b) cannot be more than 1.5mm; (b-d) cannot be greater than 3.0mm.

Compare in current design, be equipped with the utility model discloses an electric water pump of permanent magnet rotor can satisfy the start-up life test that is greater than 30 ten thousand cycles, guarantees that electric water pump uses the back for a long time, and not hard up phenomenon can not appear in the portion of moulding plastics and permanent magnet, does not start the noise of striking each other.

As shown in fig. 6, the present invention further provides an electric water pump equipped with the above permanent magnet rotor, which includes a rotating shaft 20 and an impeller 40, wherein the permanent magnet rotor is rotatably sleeved on the rotating shaft 20 through a shaft hole 32, the rotating shaft 20 can be driven to rotate by adopting a starting structure disclosed in chinese patent CN203500035U of the present applicant, and the impeller 40 is fixedly connected to the rotating shaft 20 and rotates synchronously with the rotating shaft 20; alternatively, the permanent magnet rotor is fixedly sleeved on the rotating shaft 20 through the shaft hole 32 (the rotating shaft 20 can be fixed by knurling interference or even integrally injection-molded by using the rotating shaft 20 as an insert) to drive the rotating shaft 20 to rotate, and then the rotating shaft 20 drives the impeller 40 to rotate by adopting a transmission device disclosed in chinese patent CN101408228B of the present applicant. The starting mechanism and the transmission device are both in the prior art and are not described in detail herein.

While particular embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: numerous changes, modifications, substitutions and alterations can be made to the described embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims (7)

1. A permanent magnet rotor for a low power electric machine comprising: the permanent magnet structure comprises a permanent magnet (10) and an injection molding part (30), wherein the permanent magnet (10) is a cylinder with the diameter of D, an oval connecting hole (11) is axially formed in the middle of the permanent magnet (10), the injection molding part (30) is formed by injection molding on the basis of the permanent magnet (10), more than 2 axially recessed concave parts (14) are arranged on the end face (12) of the permanent magnet (10) at intervals around the connecting hole (11), the injection molding part (30) coats all or part of the connecting hole (11), the concave parts (14) and the end face (12), and a cylindrical shaft hole (32) which is used for a rotor shaft of the motor to pass through and has the diameter of D is formed in the center of the injection molding part (30); the method is characterized in that: d =15mm-23mm, D/D =15% -25%.

2. A permanent magnet rotor according to claim 1, characterised in that the oblong connecting holes (11) have a major diameter a and a minor diameter b, with: 0.6mm to (a-b) to 1.5mm and 1.5mm to (b-d) to 3mm.

3. A permanent magnet rotor according to claim 1 or 2, characterized in that the end surface (12) of the permanent magnet (10) is provided with a conical surface (13) at the periphery of the connection hole (11) inclined towards the inner wall of the connection hole (11), and that the recess (14) comprises a first end (141) and a second end (142), the first end (141) communicating with the conical surface (13), and the second end (142) being at a distance from the first end (141) radially outwards along the end surface (12).

4. A permanent magnet rotor according to claim 3, characterized in that the number of recesses (14) is not less than 4.

5. A permanent magnet rotor according to claim 3, characterized in that the width of the first end (141) is equal to the width of the second end (142).

6. A permanent magnet rotor according to claim 3, characterised in that the width of the first end (141) is smaller than the width of the second end (142).

7. An electric water pump, comprising a rotating shaft (20), an impeller (40) and the permanent magnet rotor of any one of claims 1 to 6, wherein the permanent magnet rotor is sleeved on the rotating shaft (20) through the shaft hole (32) to drive the rotating shaft (20) and the impeller (40) to rotate together.

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