Rotor of permanent magnet motor, permanent magnet motor and air blower

Abstract

The present disclosure relates to a rotor (101) of a permanent magnet motor configured to drive an impeller of a blower, the rotor (101) comprising a shaft and a set of permanent magnets (103) wound around the shaft by a sleeve (102), where the shaft further comprises a blind hole (104) configured as a cooling channel, the blind hole (104) extending axially and centrally from a first open end to a second closed end, the shaft also includes a set of open holes (106, 202) connected to the blind hole (104) at the second closed end and extending toward an exterior of the shaft. According to the present disclosure, a rotor of a permanent magnet motor can be provided, which can be more effectively cooled without compromising the normal operation of the motor. The disclosure also relates to a permanent magnet motor and a blower.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of air blower driven by permanent magnet motor, more specifically, it is related to the rotor of this permanent magnet motor. BACKGROUND

[0002] Air blower or simply referred to as hair dryer is a kind of machine that exchanges energy between fluid flow and blade system performing rotary movement. In the case of air blower, the blade system is also referred to as impeller.

[0003] The impeller provides flow and is driven by a motor, such as a permanent magnet motor. The permanent magnet motor comprises a stator and a rotor. The rotor can then directly drive the impeller by a direct mechanical connection of the impeller to the rotor of the motor.

[0004] The rotor can comprise a set of permanent magnets and a stator comprising a set of windings and winding heads. In the windings, in combination with the winding heads, a rotating magnetic field is generated which in turn rotates the rotor to drive the impeller. During operation, the rotor and the stator will generate heat. For reasons of safety and efficiency as well as machine lifetime, this heat has to be dissipated by providing a cooling system.

[0005] In CN207518404, an electric motor is disclosed in which the rotor is cooled by passing an air flow over and around the rotor. However, a problem that can arise is that the cooling is superficial and that too large temperature gradients can arise locally. This can hamper the normal operation of the motor.

[0006] It is therefore an object of the utility model to provide a rotor of a permanent magnet motor which can be cooled more effectively without hampering the normal operation of the motor. SUMMARY

[0007] According to the utility model, the above-mentioned object is achieved by a rotor of a permanent magnet motor according to the first aspect of the utility model, the rotor being configured to drive an impeller of an air blower, the rotor comprising a shaft and a set of permanent magnets wound around the shaft by a sleeve, wherein the shaft further comprises a blind hole configured as a cooling channel, the blind hole extending axially and centrally from a first open end to a second closed end, the shaft further comprising a set of open holes connected to the blind hole at the second closed end and extending towards the outside of the shaft.

[0008] Certain terms or definitions are used to describe the utility model. Here, "direction" is understood to mean an (imaginary) line along which something can be moved, while "pointing" is understood to mean which side of this line the movement can be directed towards, as indicated by the direction.

[0009] The rotor is configured to drive an impeller of a blower. To this end, it is provided with a set of permanent magnets wound around the shaft of the rotor. These permanent magnets are fixedly held around the shaft by a sleeve. Other names for the sleeve are collet, tube or hose. The sleeve is for example a carbon fiber layer which can be said to form a one-piece tube. The sleeve can also be a metal tube which is heated to slide over the cylindrical magnets and thus fixedly hold them. The permanent magnet motor in which the rotor is fitted comprises a stator with windings and a winding head for generating a rotating magnetic field.

[0010] Furthermore, the rotor shaft comprises a blind hole over an axial length. Thus, the hole extends axially and centrally in the shaft from one end. For the blind hole it must be understood that the hole does not extend over the entire length, but is limited to a certain depth which is the length between the first open end and the second closed end. Thus, the feature "closed end" also relates to the blind hole, but, as will be further explained, from this closed end to the outside of the shaft a further opening is provided.

[0011] The hole also has a certain circumference which is determined by the diameter or radius of the hole. In order to avoid unbalance, the diameter is preferably uniform over the length. However, it should be understood that during the manufacture of the rotor, due to the provision of the hole, a slight deviation from the circumference over the length can occur.

[0012] Furthermore, the shaft comprises an open hole which is connected to the blind hole and extends to the outside or circumference of the shaft. This allows air to flow between the first open end to the second closed end and then through the open hole to the outside of the shaft.

[0013] According to one embodiment, the blind hole of the rotor also comprises cooling fins. These cooling fins can be inserted into the hole and ensure that the cooling surface in the hole is increased. Alternatively, the cooling fins can also be grooves in the hole and comprise a thread profile. Furthermore, these cooling fins in the hole can comprise or exhibit a helical pattern, viewed in the axial direction. As a result, the cooling surface is even further increased over the length. Furthermore, according to one embodiment, the rotor can comprise an axial fan at the first open end. The term "axial fan" must be understood to mean a fan in which the air flow moves in a longitudinal direction, wherein this longitudinal direction and thus the axial direction corresponds to the longitudinal direction of the shaft and thus to the longitudinal direction of the blind hole. In this case, the axial fan is driven by the rotation of the rotor itself. In other words, the term "axial fan" must also be understood to mean mechanical blades which cause the displacement of air, thus not externally driven.

[0014] Further, according to an embodiment, a stationary tube can be mounted in a bore fixed to the housing of the motor. Through this non-rotating tube, cooling medium under a certain pressure can be supplied from the outside of the blower. This allows the cooling medium to flow through the set of open holes to the outside of the rotor. Further, a part of the cooling medium can flow back to the open end along the space between the stationary tube and the inner wall of the bore in order to obtain more cooling of the shaft.

[0015] The set of holes can be configured in different ways, as will be further explained.

[0016] According to a first configuration, the set of open holes are radial holes, wherein the second closed end is the center. This means that the open holes extend perpendicularly to the direction of the shaft and thus of the blind holes, and radially from the center of the second end towards the outside of the shaft.

[0017] A second configuration is a configuration wherein the angle between the semi- angle according to the direction of the blind hole on the one hand and the semi-angle according to the direction of the respective open hole on the other hand, with the center at the closed end as corner point, is obtuse. In other words, the open holes extend obliquely towards the outside according to the direction from the open end to the closed end. This has the advantage that when the gas flow flows through the blind holes to the set of open holes, the gas flow does not have to change direction abruptly. This also reduces the chance of unwanted vibrations of the rotor when it rotates around its shaft and the mechanical losses resulting therefrom.

[0018] A third configuration is a configuration wherein the set of open holes tangentially connects to the circumference of the second closed end. This means that the open holes do not point to the center of the second closed end, and thus not to the shaft, but to a point that is offset from the center of the second end in a radial direction. This point lies at or on the circumference of the second closed end. Two alternative configurations are then possible.

[0019] A first alternative configuration is a configuration wherein the direction of the open holes is parallel to a plane perpendicular to the axial axis of the rotor. In other words, this means that the angle between the semi-angle according to the direction of the blind hole and the semi-angle according to the direction of the respective open hole, with the point on the circumference of the closed end as corner point, comprises a right angle.

[0020] A second alternative configuration is a configuration wherein the direction of the open holes is at an angle to a plane perpendicular to the axial axis of the rotor. In other words, this means that the angle between the semi-angle according to the direction of the blind hole and the semi-angle according to the direction of the respective open hole, with the point on the circumference of the closed end as corner point, comprises an obtuse angle.

[0021] Since the open holes are tangentially connected to the circumference of the second closed end, the cooling medium will also be able to flow tangentially from the closed end to the outside of the rotor. When used as a method of cooling the rotor by allowing the cooling medium to flow through the blind hole to the set of open holes and outwards as the rotor rotates, preferably the direction of rotation of the rotor is opposite to the pointing of the flow of the cooling medium out of the rotor projected onto the arc of a circle with the centre of the second end as centre, and the circle further comprises the open holes on the outside of the rotor as points of the circle.

[0022] According to a preferred embodiment, according to each of the above configurations and alternatives, the open holes are distributed rotationally symmetrically and / or line symmetrically. The point of rotational symmetry is then on the axial axis of the rotor. The line of line symmetry is then the axial axis of the rotor.

[0023] Furthermore, the hole can also be a continuous hole instead of a blind hole, and thus extend over the entire length of the shaft. In this case, the cooling medium can be drawn in from both sides of the rotor. In addition, according to the same configurations and alternatives as described above, both ends can be provided with a set of open holes.

[0024] It should be noted that the rotor comprising a cooling channel as described above is also applicable to machines with a shaft without permanent magnets, such as solid rotor induction motor technology, and to generator applications in addition to motor applications.

[0025] According to an embodiment, the rotor further comprises a conduit configured to supply cooling medium to the cooling channel. The conduit is provided at the first open end and is configured to blow cooling medium, such as air, into the cooling channel. This causes the cooling medium to flow through the blind hole to the second closed end and then through the set of open holes. The conduit can be rigidly positioned at the first open end and partially inserted into the blind hole, whereby there is no contact between the conduit and the wall of the blind hole. This then prevents the conduit from rotating when the rotor is rotating while housed in a motor and the motor is in operation.

[0026] According to an embodiment, the conduit is a hollow tube configured to guide cooling medium from the first open end to the second closed end, and the outer radius of the hollow tube is smaller than the radius of the blind hole, so that the air flow can be further guided between the circular ring at the first open end and the circular ring at the second closed end.

[0027] A circular ring, also called an annulus, is a ring-shaped geometry with an inner radius and an outer radius. In this case, the inner radius of the circular ring is the outer radius of the hollow tube, and the outer radius of the circular ring is the radius of the blind hole. The hollow tube is then mounted in the blind hole with one end up to the second closed end. This creates an open surface that is the same as the circular ring and extends axially over the blind hole. The cooling medium can then flow through this open surface, as will be further explained.

[0028] According to one embodiment, the rotor further comprises a second set of open holes adjacent the blind hole at a position between the first open end and the second closed end and extending to the outside of the shaft. This second set of open holes can then have the same properties as the set of open holes already discussed above.

[0029] According to a second aspect of the present invention, a permanent magnet motor is disclosed, configured to drive an impeller of a blower, comprising a stator and a rotor according to the first aspect of the present invention.

[0030] According to one embodiment, the stator comprises winding heads behind its end portions, and the set of open holes is directed towards these winding heads of the stator. This allows the winding heads to be effectively cooled.

[0031] Furthermore, winding heads can exist on both sides of the stator, and the rotor can have holes as cooling channels, which extend over the entire length. Here, a set of open holes is also provided on both sides, which are then directed towards the respective winding heads to cool them.

[0032] According to a third aspect of the present invention, a blower is disclosed, comprising an impeller and a permanent magnet motor according to the second aspect of the present invention for driving the impeller.

[0033] According to a fourth aspect of the present invention, a method of cooling a rotor of a permanent magnet motor according to the second aspect of the present invention is disclosed, comprising the step of flowing a cooling medium through the blind hole to the set of open holes. Preferably, the cooling medium is air, but in general, it can also be another gas.

[0034] According to one embodiment, the cooling further comprises the step of flowing the cooling medium through the conduit up to the second closed end, and wherein the cooling medium is further distributed on the one hand to the set of open holes and on the other hand from the annulus at the second closed end to the annulus at the first open end.

[0035] The cooling medium is injected into the blind hole up to the second closed end. At this position, the cooling medium is then distributed on the one hand over the open holes and on the other hand over the axial volume formed by the annulus, i.e. over the space between the tube and the blind hole. As a result, part of the cooling medium is directed back to the first open end.

[0036] In addition to the above rotor application to a blower driven by a permanent magnet motor, this can also be applied to other technologies, such as compressors and expanders. BRIEF DESCRIPTION OF DRAWINGS

[0037] The present invention will be further described with reference to the drawings, in which

[0038] Figure 1A cross section of a permanent magnet motor according to a first embodiment of the present application is shown;

[0039] Figure 2 A cross section of a permanent magnet motor according to a second embodiment of the present application is shown; and

[0040] Figure 3 A cross section of a set of open holes according to an embodiment of the present application is shown;

[0041] Figure 4 A cross section of a permanent magnet motor according to a third embodiment of the present application is shown; and

[0042] Figure 5 A cross section of a permanent magnet motor according to a fourth embodiment of the present application is shown. DETAILED DESCRIPTION

[0043] The present application will be described with reference to certain embodiments and to certain drawings but the application is not limited thereto and is only defined by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements can be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not necessarily correspond to the actual proportions in a patentable application.

[0044] Moreover, the use of the terms first, second, third, etc. do not necessarily indicate an order of one before another or one before another but rather are used for distinguishing between two elements having a same or similar nature. The terms first, second, third, etc. are interchangeable under appropriate circumstances and embodiments of the application can operate in other sequences than described or illustrated herein.

[0045] Furthermore, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. The terms top, bottom, over, under and the like are interchangeable under appropriate circumstances and embodiments of the application described herein can operate in other orientations than described or illustrated herein.

[0046] In addition, while the various embodiments of the application have been described above, it should be understood that they have been presented by way of example only, and not limitation. Numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of the application.

[0047] The term "comprising", as used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, elements, steps or components as referred to, but does not preclude the presence or addition of one or more other features, elements, steps or components or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, only the components A and B are required, but not excluding the presence of one or more other components.

[0048] Figure 1 A cross-section of a permanent magnet motor according to an embodiment of the present invention is shown. Here, there is a stator 105 and a rotor 101. In this illustration, the stator 105 is shown on only one side, but it should also be understood that in a practical embodiment of the present invention, the stator 105 extends completely around the rotor 101. It should also be understood that there are also bearings at the ends of the rotor 101 to maintain it in its radial and axial position.

[0049] The stator 105 comprises windings as indicated by reference 107. These windings 107 provide a rotating magnetic field that drives the rotor 101 comprising permanent magnets 103. These permanent magnets 103 are permanently held in place by a sleeve 102.

[0050] It is an object of the present invention to cool a permanent magnet motor, more specifically the rotor, by providing air ducts through which air can flow for cooling. A first air duct 108 is located between the stator 105 and the rotor 101 and more specifically between the stator 105 and the sleeve 102 of the rotor. This air duct is also referred to as the air gap of the motor. Furthermore, the rotor 101 has on one side a hole 104 along the shaft of the rotor 101. This hole 104 is a blind hole, extending axially to the other end of the rotor 101, without extending over the entire shaft or length of the rotor 101. On the other end, there are then a set of open holes 106 connected to the blind hole 104. This allows the air flow to flow through the hole 104 to the open holes 106 and to the outside. The blind holes 106 are then oriented in such a way that they cool the windings 107 at the end of the stator 105.

[0051] In Figure 1 In the embodiment shown, the open holes 106 taper or are inclined towards the outer circumference of the rotor 101 when viewed from the direction of the opening on the hole 104 to the open holes 106. As a result, the air flow will not experience a sudden change in direction, preventing an undesired pressure drop in the rotor flow.

[0052] In Figure 2The second embodiment of this utility model is disclosed herein. Here again, a stator 105, a group of permanent magnets 103, and a sleeve 102 are provided. As already described... Figure 1 As illustrated in the diagram, an air passage 108 is also provided between the stator 105 and the rotor 101. Furthermore, a winding head 202 is provided at the end.

[0053] Here, the opening 201 is oriented perpendicular to the axis of the rotor 101. In this embodiment, the opening 201 also points towards the winding head 202 of the stator 105.

[0054] As shown in this embodiment, cooling fins 204 can also be disposed in the holes 104. Note that these cooling fins 204 can also be present in... Figure 1 In the illustrated embodiment, these cooling fins 204 ensure an increased cooling surface area compared to embodiments without cooling fins 204. These cooling fins 204 may be arranged in an axial direction or may follow other patterns, such as a spiral pattern.

[0055] Furthermore, as indicated by reference numeral 203 in the attached drawing, an axial flow fan can also be installed at the open end of the blind hole 104. Again, note that this axial flow fan 203 can also be installed as shown in... Figure 1 In the rotor shown.

[0056] The axial fan 203 then ensures that air is drawn in when the rotor 101 rotates. The air intake occurs axially toward the interior of the rotor toward the openings 106, 201 in the direction of the axial fan 203.

[0057] Figure 3 An embodiment of the configuration 300 of the set of openings 106, 201 is further shown. The figure is a cross-section of the rotor as observed at the second end, i.e., at the set of openings.

[0058] According to the illustrated embodiment 300, the openings, such as openings 301 and 302, are not radially oriented toward the center 304 of the rotor, but rather toward a point on the circumference of the second end. As a result, an angle exists between the orientation of the openings and the radial direction (i.e., toward the center 304). This angle is indicated by reference numeral 303.

[0059] like Figure 3 The illustrated embodiment 300 is also related to, for example Figure 1 The embodiments shown and as Figure 2 The illustrated embodiment is compatible. This means that the group of openings 301, 302 pointing toward corresponding points on the circumference have a direction parallel to a plane perpendicular to the axial direction of the rotor shaft (e.g., Figure 2 (as shown), or at a certain angle to the plane (such as...) Figure 1 (As shown).

[0060] Figure 4 One embodiment of the rotor is shown, wherein a duct 401 is provided to inject a cooling medium into the blind hole. The cooling medium is then injected from the first open end 404 until the second closed end 402. Here, a part of the cooling medium is then further guided to the open holes 106. Another part is then axially flowing back to the open end 404. This is shown by reference 403, which refers to the space between the duct 401 and the outer circumference of the blind hole. The volume of this space then depends on the difference between the outer radius of the duct 402 and the radius of the blind hole.

[0061] Figure 5 One embodiment is shown, wherein the rotor is also provided with a second set of open holes 602, thus a set of open holes in addition to the set of open holes referenced as 201. It is noted that the properties of this second set of open holes correspond to the properties of the first set of open holes, and thus they can also be designed as the set of open holes referenced as 106 in the embodiment of Figure 1 "corresponding" also means that the second set of open holes can be designed for example according to the set of open holes referenced as 106 and according to the first set of open holes referenced as 201. The advantage of the second set of open holes 602 is that the winding head 601 on the side of the first open end 203 can also be effectively cooled.

Claims

1. A rotor of a permanent magnet motor, characterized by, The permanent magnet motor is configured to drive an impeller of a blower, the rotor comprising a shaft and a set of permanent magnets wound by a sleeve around the shaft, wherein the shaft further comprises a blind hole configured as a cooling channel, the blind hole extending axially and centrally from a first open end to a second closed end, the shaft further comprising a set of open holes connected to the blind hole at the second closed end and extending towards the outside of the shaft.

2. The rotor of a permanent-magnet motor according to claim 1, characterized by The set of open holes comprises radial holes centered on the second closed end.

3. The rotor of a permanent-magnet motor according to claim 1, characterized by An angle between a half-angle according to the direction of the blind hole and a half-angle according to the direction of the respective open hole comprises an obtuse angle with the second closed end as a corner point.

4. The rotor of a permanent-magnet motor according to claim 1, characterized by The set of open holes is tangentially connected to the circumference of the second closed end.

5. The rotor of a permanent-magnet motor according to claim 4, characterized in that An angle between a half-angle according to the direction of the blind hole and a half-angle according to the direction of the respective open hole comprises a right angle with a point on the circumference of the second closed end as a corner point.

6. The rotor of a permanent-magnet motor according to claim 4, characterized by An angle between a half-angle according to the direction of the blind hole and a half-angle according to the direction of the respective open hole comprises an obtuse angle with a point around the circumference of the second closed end as a corner point.

7. The rotor of a permanent-magnet motor according to any one of claims 1 to 6, characterized in that The set of open holes is rotationally and / or line symmetrically distributed.

8. The rotor of a permanent-magnet motor according to any one of claims 1 to 6, characterized in that The blind hole further comprises cooling fins.

9. The rotor of a permanent-magnet motor according to claim 8, characterized in that The cooling fins comprise a helical pattern in axial direction.

10. The rotor of a permanent-magnet motor according to any one of claims 1 to 6, characterized in that A axial fan is further comprised at the first open end.

11. The rotor of a permanent-magnet motor according to any one of claims 1 to 6, characterized in that A conduit is further comprised, the conduit being configured to supply a cooling medium to the cooling channel.

12. The rotor of a permanent-magnet motor according to claim 11, characterized in that The conduit comprises a hollow tube configured to guide the cooling medium from the first open end to the second closed end, and wherein an outer radius of the hollow tube is smaller than a radius of the blind hole, such that the cooling medium can be further guided between a circular ring at the first open end and a circular ring at the second closed end.

13. The rotor of a permanent-magnet motor according to any one of claims 1 to 6, characterized in that A second set of open holes is further comprised, the second set of open holes being connected to the blind hole at a position between the first open end and the second closed end and extending towards the outside of the shaft.

14. A permanent magnet motor configured to drive an impeller of a blower, characterized by The permanent magnet motor comprises a stator and a rotor according to any of claims 1-13.

15. The permanent magnet motor of claim 14, wherein, The stator comprises one or more winding heads, and wherein the open holes are directed towards the winding heads of the stator.

16. A blower characterized by The blower comprises an impeller and a permanent magnet motor according to claim 14 or 15, the permanent magnet motor being configured to drive the impeller.

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