Rotor of permanent magnet motor for driving impeller of blower

Abstract

According to one embodiment, there is disclosed 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) wherein the shaft further comprises a blind hole (104) configured as a cooling channel, the shaft includes a blind bore (104) extending axially and centrally from a first open end to a second closed end, the shaft further including a set of open bores (106, 202) connected to the blind bore (104) at the second closed end and extending toward an exterior of the shaft.

Description

Technical Field

[0001] The present invention relates to a blower driven by a permanent magnet motor, and more particularly to a rotor of the permanent magnet motor. Background Art

[0002] A blower or simply a hair dryer is a machine that exchanges energy between a fluid flow and a blade system that performs a rotational movement. In the case of a blower, the blade system is also called an impeller.

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

[0004] The rotor may include a set of permanent magnets and a stator, which includes 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 stator will generate heat. For reasons of safety and efficiency as well as machine life, this heat must be dissipated by providing a cooling system.

[0005] CN207518404 discloses an electric motor in which the rotor is cooled by passing an air flow over and around the rotor. However, a problem that may occur is that the cooling is superficial and local temperature gradients that are too large may occur. This may prevent the normal operation of the motor.

[0006] It is therefore an object of the present invention to provide a rotor of a permanent magnet motor which can be cooled more effectively without impairing the proper operation of the motor. Summary of the invention

[0007] According to the present invention, the above-mentioned object is achieved by providing a rotor of a permanent magnet motor according to the first claim according to a first aspect of the present invention, the rotor being configured to drive an impeller of a blower, the rotor comprising a shaft and a group of permanent magnets wound around the shaft through 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, and the shaft further comprises a group of open holes connected to the blind hole at the second closed end and extending toward the outside of the shaft.

[0008] Certain terms or definitions are used to describe the present invention. Here, "direction" is understood to mean an (imaginary) line along which movement is possible, while "pointing" is understood to mean towards which side of the line indicated by the direction movement is possible.

[0009] The rotor is designed to drive the impeller of a blower. For this purpose, it is provided with a group of permanent magnets wound around the shaft of the rotor. These permanent magnets are fixedly held around the shaft by means of a sleeve. Other names for the sleeve are a chuck, a tube or a hose. The sleeve is, for example, a carbon fiber layer, which forms, so to speak, a one-piece tube. The sleeve can also be a metal tube, which is heated so as to slide over the cylindrical magnets and thus hold them fixedly. The permanent magnet motor in which the rotor is assembled comprises a stator with a winding and a winding head for generating a rotating magnetic field.

[0010] Furthermore, the rotor shaft comprises a blind hole over a certain axial length. Thus, the hole extends axially and centrally in the shaft starting from one end. With a 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 a first open end and a second closed end. Thus, the feature "closed end" also relates to a blind hole, but, as will be explained further, a further opening is provided starting from this closed end to the outside of the shaft.

[0011] The hole also has a certain circumference determined by the diameter or radius of the hole. To avoid imbalance, the diameter is preferably uniform over the length. However, it should be understood that during the manufacture of the rotor, slight deviations from the circumference may occur over the length due to the arrangement of the hole.

[0012] In addition, the shaft includes an open hole connected to the blind hole and extending to the exterior or periphery of the shaft. This allows air to flow between the first open end to the second closed end and then reach the exterior of the shaft through the open hole.

[0013] According to one embodiment, the blind hole of the rotor also includes 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 include a thread profile. In addition, these cooling fins in the hole can include or present a spiral pattern when viewed in the axial direction. As a result, the cooling surface is even further increased over this length. In addition, according to one embodiment, the rotor can include an axial fan at the first open end. The term "axial fan" must be understood to mean a fan in which the airflow moves in a longitudinal direction, wherein the longitudinal direction and therefore the axial direction correspond to the longitudinal direction of the shaft and therefore 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 a mechanical blade that causes air displacement and is therefore not externally driven.

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

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

[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 are perpendicular to the direction of the shaft and thus the blind hole, and extend radially from the center of the second end toward the outside of the shaft.

[0017] The second configuration is a configuration in which the angle between the semi-right according to the direction of the blind hole on the one hand and the semi-right according to the direction of the corresponding opening hole on the other hand is an obtuse angle with the center at the closed end as the corner point. In other words, the opening hole extends obliquely toward the outside according to the direction from the open end to the closed end. This has the advantage that the airflow does not have to change direction suddenly when it flows through the blind hole to the group of opening holes. This also reduces the chance of undesirable vibrations of the rotor when it rotates around its axis and the resulting mechanical losses.

[0018] A third configuration is one in which the set of open holes is connected tangentially to the circumference of the second closed end. This means that the open holes are not directed towards the center of the second closed end, and thus not towards the axis, but towards a point offset in a radial direction away from the center of the second end. This point is located at or on the circumference of the second closed end. Thus, two alternative configurations are possible.

[0019] A first alternative configuration is a configuration in which the direction of the opening hole is parallel to a plane perpendicular to the axial axis of the rotor. In other words, this means that the angle between the half angle according to the direction of the blind hole and the half angle according to the direction of the corresponding opening hole includes a right angle when a point on the circumference of the closed end is used as a corner point.

[0020] A second alternative configuration is a configuration in which the direction of the opening hole 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 half angle according to the direction of the blind hole and the half angle according to the direction of the corresponding opening hole with a point on the circumference of the closed end as a corner point includes an obtuse angle.

[0021] Because the opening 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 holes to the set of opening holes and flow outwardly as the rotor rotates, preferably the direction of rotation of the rotor is opposite to the direction in which the cooling medium flows out of the rotor projected onto an arc of a circle centered on the center of the second end, and the circle also includes the opening 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 openings are distributed rotationally symmetrically and / or lineally symmetrically. The rotationally symmetrical point is then located on the axial axis of the rotor. The line of lineal symmetry is then the axial axis of the rotor.

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

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

[0025] According to one embodiment, the rotor further comprises a conduit configured to supply a cooling medium to the cooling channel. The conduit is arranged at the first open end and is configured to blow a 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 may 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 housed in the motor and the motor is functioning.

[0026] According to one embodiment, the conduit is a hollow tube configured to guide the 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 torus, also called a ring, is a ring-shaped geometric figure with an inner radius and an outer radius. In this case, the inner radius of the torus is the outer radius of the hollow tube, and the outer radius of the torus is the radius of the blind hole. The hollow tube is then installed in the blind hole with one end up to the second closed end. This creates an open surface that is identical to the torus and extends axially over the blind hole. As will be explained further, the cooling medium can then flow through this open surface.

[0028] According to one embodiment, the rotor further comprises a second set of open holes adjacent to the blind hole at a position between the first open end and the second closed end and extending to the outside of the shaft. The second set of open holes can then have the same characteristics 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, which is 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 ends, and the open holes of the set are directed towards these winding heads of the stator. This allows these winding heads to be cooled effectively.

[0031] In addition, there can be winding heads on both sides of the stator, and the rotor can have holes as cooling channels, which extend over the entire length. Here, groups of open holes are also provided on both sides, which are then directed toward the corresponding 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 invention, a method of cooling a rotor of a permanent magnet motor according to the second aspect of the 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 generally, it may also be another gas.

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

[0035] The cooling medium is injected into the blind hole up to the second closed end. At this point, the cooling medium is then distributed on the one hand over the opening hole and on the other hand over the axial volume formed by the ring, 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] Besides the application of the above-described rotor to blowers driven by permanent magnet motors, this can also be applied to other technologies such as compressors and expanders. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0038] Figure 1 shows a cross section of a permanent magnet motor according to a first embodiment of the present invention;

[0039] Figure 2 shows a cross section of a permanent magnet motor according to a second embodiment of the invention; and

[0040] Figure 3 shows a cross section of a group of open holes according to an embodiment of the present invention;

[0041] Figure 4 shows a cross section of a permanent magnet motor according to a third embodiment of the present invention; and

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

[0043] The present invention will be described with reference to certain embodiments and with reference to certain drawings, but the invention is not limited thereto and is limited only by the claims. The drawings described are only schematic and non-restrictive. In the drawings, for illustrative purposes, the dimensions of certain elements may be exaggerated and not drawn to scale. The dimensions and relative sizes do not necessarily correspond to actual embodiments of the present invention.

[0044] Furthermore, the terms first, second, third, etc. are used in the description and claims to distinguish similar elements without necessarily describing a sequential or chronological order. These terms are interchangeable under appropriate circumstances, and the embodiments of the invention may be implemented in an order other than that described or illustrated herein.

[0045] In addition, the terms above, below, over, under, etc. are used in the specification and claims for illustrative purposes and not necessarily to describe relative positions. The terms so used are interchangeable where appropriate, and the embodiments of the invention described herein may be implemented in other than those described or illustrated herein.

[0046] Furthermore, although referred to as "preferred forms," ​​the various embodiments should be construed as examples of how the invention may be practiced rather than limitations on the scope of the invention.

[0047] The term "comprising" used in the claims should not be interpreted as being limited to the means or steps listed thereafter; the term should not exclude other elements or steps. The term should be interpreted as specifying the presence of the specified features, elements, steps or components mentioned, but should not exclude the presence or addition of one or more other features, elements, steps or components or combinations thereof. Therefore, the scope of the expression "a device comprising means A and B" should not be limited to a device consisting of only components A and B. The meaning is that, for the present invention, only components A and B of the device are listed, and the claims should also be interpreted as including equivalents of these components.

[0048] Figure 1 A cross section of a permanent magnet motor according to an embodiment of the invention is shown. Here, there is a stator 105 and a rotor 101. In this illustration, the stator 105 is shown on one side only, but it should also be understood that in a practical embodiment of the 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 numeral 107. These windings 107 provide a rotating magnetic field which drives the rotor 101 comprising permanent magnets 103. These permanent magnets 103 are permanently held in place by sleeves 102.

[0050] The object of the present invention is to cool a permanent magnet motor, more specifically, a rotor, by providing an air duct 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. In addition, the rotor 101 has a hole 104 along the axis of the rotor 101 on one side. The hole 104 is a blind hole that extends axially to the other end of the rotor 101 without extending over the entire axis or length of the rotor 101. At the other end, there are groups of open holes 106 connected to the blind holes 104. This allows the airflow to flow through the holes 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 ends of the stator 105.

[0051] exist Figure 1 In the illustrated embodiment, the opening holes 106 taper or slope gradually toward the periphery of the rotor 101 when viewed from the opening on the bore 104 to the opening holes 106. As a result, the airflow will not experience a sudden change in direction, thereby preventing undesirable pressure drops in the rotor flow.

[0052] exist Figure 2 In the second embodiment of the present invention, a stator 105, a set of permanent magnets 103 and a sleeve 102 are provided again. Figure 1 As illustrated in the figure, an air passage 108 is also provided between the stator 105 and the rotor 101. In addition, a winding head 202 is provided at the end.

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

[0054] As shown in this embodiment, cooling fins 204 may also be provided in the holes 104. Note that these cooling fins 204 may also be present in the Figure 1In the embodiment shown, these cooling fins 204 ensure that the cooling surface is increased compared to embodiments in which no cooling fins 204 are present. These cooling fins 204 may be arranged in an axial direction or may follow another pattern, for example a spiral pattern.

[0055] In addition, as shown by reference numeral 203, an axial flow fan may be provided at the open end of the blind hole 104. Figure 1 The rotor shown.

[0056] This axial fan 203 then ensures that air is sucked in when the rotor 101 rotates. The suction takes place axially in the direction of the axial fan 203 towards the inside of the rotor towards the opening holes 106, 201.

[0057] Figure 3 Further shown is an embodiment of a configuration 300 of the set of open holes 106, 201. The figure is a cross section of the rotor viewed at the second end, ie at the set of open holes.

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

[0059] like Figure 3 The embodiment 300 shown is also similar to Figure 1 The embodiments shown and Figure 2 This means that the groups of opening holes 301, 302 pointing towards 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 ), or at an angle to the plane (as shown in Figure 1 as shown).

[0060] Figure 4 An embodiment of a rotor is shown, in which 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 up to the second closed end 402. Here, part of the cooling medium is then further directed to the open hole 106. Another part then flows back axially to the open end 404. This is shown by reference numeral 403, which refers to the space between the duct 401 and the outer periphery 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 5An embodiment is shown in which the rotor is also provided with a second set of opening holes 602, thus in addition to the set of opening holes referenced 201. Note that the properties of this second set of opening holes correspond to the properties of the first set of opening holes, and thus they can also be Figure 1 "Corresponding" also means that the second group of opening holes can be designed, for example, according to the group of opening holes marked 106 in the figure and according to the first group of opening holes marked 201 in the figure. The advantage of the second group of opening holes 602 is that the winding head 601 on one side of the first open end 203 can also be effectively cooled.

Claims

1. A rotor (101) of a permanent magnet motor, the permanent magnet motor being configured to drive an impeller of a blower, the rotor (101) comprising a shaft and a group of permanent magnets (103) wound around the shaft by a sleeve (102), wherein 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, and the shaft further comprises a group of open holes (106, 201) connected to the blind hole (104) at the second closed end and extending toward the outside of the shaft.

2. The rotor (101) according to claim 1, wherein: The group of open holes includes a radial hole (201) centered on the second closed end.

3. The rotor (101) according to claim 1, wherein: With the closed end as the corner point, the angle between the half angle according to the direction of the blind hole (106) on the one hand and the half angle according to the direction of the corresponding opening hole (106) on the other hand comprises an obtuse angle.

4. The rotor (101) according to claim 1, wherein: The group of open holes (302, 303) are tangentially connected to the circumference of the second closed end.

5. The rotor (101) according to claim 4, wherein: In the case of a point on the circumference of the closed end as a corner point, the angle between the half angle according to the direction of the blind hole on the one hand and the half angle according to the direction of the corresponding opening hole on the other hand comprises a right angle.

6. The rotor (101) according to claim 4, wherein: The angle between the half angle according to the direction of the blind hole on the one hand and the half angle according to the direction of the corresponding opening hole on the other hand comprises an obtuse angle when a point around the circumference of the closed end is used as a corner point.

7. A rotor (101) according to any one of the preceding claims, wherein: The groups of opening holes are distributed rotationally symmetrically and / or line-symmetrically.

8. A rotor (101) according to any one of the preceding claims, wherein: The blind hole also includes a cooling fin (204).

9. The rotor (101) according to claim 8, wherein: The cooling fin (204) comprises a spiral pattern along the axial direction.

10. The rotor (101) according to any one of the preceding claims, further comprising an axial fan (203) located at the first open end (104).

11. The rotor (101) according to any one of the preceding claims, further comprising a duct configured to supply a cooling medium to the cooling channel.

12. The rotor (101) according to claim 11, wherein: The conduit comprises a hollow tube (401) configured to guide the cooling medium from the first open end (404) to the second closed end (402), and wherein an outer radius of the hollow tube (401) is smaller than a radius of the blind hole (104), so that the air flow can be further guided between the circular ring at the first open end (404) and the circular ring at the second closed end (402).

13. The rotor (101) according to any one of the preceding claims, further comprising a second set of open holes (602) 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, the permanent magnet motor comprising a stator (105) and a rotor (101) according to any one of the preceding claims.

15. The permanent magnet motor according to claim 14, wherein: The stator (105) comprises one or more winding heads (107, 202), and wherein the opening holes (106, 201) are directed towards the winding heads (107, 202) of the stator.

16. A blower comprising an impeller and a permanent magnet motor according to any one of claims 14 to 15, the permanent magnet motor being configured to drive the impeller.

17. A method of cooling a permanent magnet motor according to any one of claims 14 to 15, comprising the step of flowing a cooling medium through the blind holes towards the set of open holes.

18. A method for cooling a permanent magnet motor configured to drive an impeller of a blower, the permanent magnet motor comprising a stator (105) and a rotor (101) according to claim 12, the method comprising the steps of causing a cooling medium to flow through the duct up to the second closed end (402) and also distributing the cooling medium on the one hand to the set of open holes and on the other hand from the annular ring at the second closed end (402) to the annular ring at the first open end (404).

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