Rotor, in particular for brushless DC motor and actuator

Abstract

The invention relates to a rotor (R), in particular for a brushless DC motor, comprising a substantially hollow cylindrical permanent magnet (2) and a substantially hollow cylindrical rotor core (1) composed of at least one laminated core arranged in the permanent magnet (2), the rotor (R) comprising a substantially hollow cylindrical plastic part (3), the plastic part is arranged between the rotor core (1) and the permanent magnets (2).

Description

Technical Field

[0001] The present invention relates to a rotor, in particular a rotor for a brushless DC motor, comprising substantially hollow-cylindrical permanent magnets and a substantially hollow-cylindrical rotor core consisting of at least one laminated core arranged in the permanent magnets. The present invention also relates to a method for producing the rotor and a motor having such a rotor. Furthermore, the present invention relates to an actuator having such a rotor. Background Art

[0002] The rotor for a brushless DC motor can, in principle, have a rotor core or can also be designed without a rotor core. The permanent magnets are therefore fixed directly to the motor shaft. To ensure a secure fit of the magnets on the motor shaft, knurling is often provided on the motor shaft. The magnets are therefore preferably connected to the motor shaft by gluing, as they are very fragile and can break during the extrusion process. A rotor without a rotor core can have a plastic injection-molded encapsulation of the permanent magnets. Due to the lack of a rotor core, motors with such a rotor often have low performance.

[0003] A rotor with a rotor core can be constructed and manufactured in various ways. For example, one method is known in which the permanent magnets and the rotor core are connected to each other by gluing. This requires the use of an adhesive that is tailored to both the components to be bonded and the operating conditions. Furthermore, for such adhesive connections, close component tolerances must be maintained, as otherwise the bond could become loose. These tight component tolerances make the components complex and expensive to manufacture.

[0004] Another method for manufacturing the rotor involves connecting the magnets to the rotor core by injection molding the magnets onto the rotor core. This creates a fixed, load-bearing connection between the magnets and the rotor core. A disadvantage of this type of rotor is that the injection-molded magnets are weaker than magnets manufactured in other ways, which can lead to a loss of motor performance. Summary of the Invention

[0005] The present invention is therefore based on the problem of improving the rotor so that, on the one hand, a reliable fixed fit of the rotor on the motor shaft and a fixed connection of the rotor core and the permanent magnets can be achieved and, on the other hand, the advantages of introducing an iron core into the magnets to increase the motor power can also be achieved, so that the motor has better performance than a motor with a rotor without a rotor core when the rotor has the same structural space.

[0006] According to the invention, this object is achieved in that the rotor has a substantially hollow cylindrical plastic component, which is arranged between the rotor core and the permanent magnets. A fixed connection is established between the rotor core and the permanent magnets by means of this plastic component. Since the rotor core is arranged inside the plastic component and the permanent magnets, the rotor core forms a component of the rotor that is connected or connected to the shaft of the motor. As experience has shown, a fixed, load-bearing connection can be achieved between the lamination stack forming the rotor core and the motor shaft without a special design of the motor shaft. Since the magnets for connecting to the rotor core are not injection-molded onto the rotor core, but the plastic component between the rotor core and the permanent magnets realizes the connection between these two components, strong magnets can be used in the rotor according to the invention. A motor with a rotor according to the invention can be more efficient than a motor with the same structural space and a rotor without a rotor core.

[0007] The laminations of the rotor core can be arranged in parallel planes perpendicular to the rotor axis.

[0008] The rotor core can have recessed and / or projecting portions on its outer side. These can be produced by having the narrow outer surfaces of the laminations not lie on the cylindrical surface, but rather be completely or partially recessed relative to or projecting relative to the cylindrical surface. By recessing or projecting the outer surfaces of the individual laminations, the lamination stack can have an outer surface with a structure comprising recessed and / or projecting portions. For example, grooves or slots can be used as recessed portions. Projecting portions can be tabs. The recessed and / or projecting portions can extend from one end of the rotor core to the other.

[0009] According to the present invention, the plastic component can have recesses and / or projections on its inner side. The projections of the rotor core can have a shape complementary to the recesses of the plastic component, and / or the recesses of the rotor core can have a shape complementary to the projections of the plastic component. Thus, the projections of one component can engage with the recesses of the other. This creates a positive-locking connection between the rotor core and the plastic component that is load-bearing in the direction of rotation of the rotor and / or in the longitudinal direction of the rotor.

[0010] The plastic component of the rotor according to the present invention may have recesses and / or protrusions at its end or on the outside. Such recesses and / or protrusions provided on the outside can extend from one end of the plastic component to the other end of the rotor core. If recesses and / or protrusions are provided at the end of the end, they can extend completely or partially from the rotor axis to the outside of the permanent magnet. A flange may also be provided, which extends inwardly toward the rotor axis or toward the outside of the permanent magnet at the end of the end. The flange may also have recesses and / or protrusions. The flange may also extend completely or partially from the rotor axis to the outside of the permanent magnet.

[0011] The permanent magnets of the rotor according to the present invention can have projections and / or recesses at their end faces or on their inner sides. The projections of the plastic component can have a shape complementary to the recesses of the permanent magnets, and / or the recesses of the plastic component can have a shape complementary to the projections of the permanent magnets. The projections of one component can engage with the recesses of the other component. This creates a positive connection between the rotor core and the plastic component that is load-bearing in the direction of rotation of the rotor and / or in the longitudinal direction of the rotor.

[0012] The rotor according to the present invention can be manufactured by a method comprising the following steps:

[0013] • Arrange the permanent magnets in the injection mold,

[0014] • arranging the rotor core in the injection mold in such a way that there is a spacing between the outer side of the rotor core and the inner side of the permanent magnets, so that a cavity is formed between the outer side of the rotor core, the inner side of the permanent magnets and one or more walls of the injection mold,

[0015] • Close the injection mold if necessary, and

[0016] • Liquid plastic is injected into the cavity.

[0017] These steps can be carried out in the order described. However, the first two steps can also be interchanged, wherein the permanent magnets can then be arranged at a certain distance from the outside of the rotor core in such a way that a cavity is formed between the outside of the rotor core, the inside of the permanent magnets, and one or more walls of the injection mold.

[0018] It is also possible to design the magnet as an injection-molded part and thus form a so-called plastic-bonded magnet. Thus, the magnet can first be injection-molded in a mold, and in a further step, the magnet and rotor core can be positioned relative to each other before the plastic used to produce the plastic component is injected. Plastic-bonded magnets and plastic components can be produced by two-component injection molding.

[0019] Finally, the object set forth at the outset can be achieved by an actuator having the aforementioned rotor. The actuator is advantageously used as a regulator for a valve or other movable object. Advantageously, the actuator is used in a vehicle, in particular in an automobile. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] An example of a rotor according to the invention is shown in the accompanying drawings. In the drawings:

[0021] Figure 1 A view showing an assembly consisting of a motor shaft according to the invention, a worm of a worm gear arranged on the motor shaft, and a rotor according to the invention arranged on the motor shaft,

[0022] Figure 2 A view showing a rotor according to the invention, and

[0023] Figure 3 An exploded view of a rotor according to the invention is shown. DETAILED DESCRIPTION

[0024] The rotor R according to the present invention has a rotor core 1 formed from a set of laminations 11. The laminations 11 in the illustrated example have the same shape. The laminations 11 are essentially annular, with the inner side 111 and outer side 112 of each lamination 11 having protruding sections 1111, 1121 and recessed sections 1112, 1122. In general, three protruding sections 1111, 1121 and three recessed sections 1112, 1122 are provided on each inner side 111 and each outer side 112, respectively. The rotor core is essentially a straight hollow cylinder. The rotor R can be connected to a worm screw thread via the rotor axis.

[0025] The rotor R according to the invention has a permanent magnet 2. The permanent magnet 2 also has the shape of a substantially straight hollow cylinder. Its inner surface 21 and its outer surface 22 are smooth. Two diametrically opposed, radially extending recesses 23 are provided on each end face.

[0026] Finally, the rotor R according to the present invention also has a plastic component 3, which is arranged essentially between the rotor core 1 and the permanent magnets 2. The portion 31 of the plastic component between the rotor core 1 and the permanent magnets 2 has the shape of a substantially straight hollow cylinder. The inner surface 311 of this component 31 is shaped complementary to the outer sides 112 of the laminations 11 of the rotor core 1, and the outer surface 312 of the component 31 is shaped complementary to the inner surfaces 21 of the permanent magnets 2. Thus, the inner surface 311 has projections and depressions, while the outer surface 312 is smooth. This creates a form-fitting, rotationally fixed connection between the rotor core 1 and the portion 31 of the plastic component 3.

[0027] The plastic component also has an inwardly projecting flange 331 and an outwardly projecting flange 332 on one of the two end faces. These flanges lie in a single plane. The inwardly projecting flange 331 overlaps and rests on the end face of the rotor core 1 located on the side of the rotor R, while the outwardly projecting flange 332 overlaps and rests on the end face of the permanent magnet 2 located on the side of the rotor R. Because the outwardly projecting flange 332 has a projection 3321 on the side of the end face facing the permanent magnet 2 (which engages in a recess 23 provided on the end face of the permanent magnet located on the side of the rotor R), a positively locking, non-rotatable connection is also established between the plastic component 3 and the permanent magnet 2. Furthermore, two radially outwardly projecting projections 32 are provided on the component 31 , more precisely at its end opposite the flanges 331 , 332 , which engage in recesses 23 in the end faces of the permanent magnets 2 on this side of the rotor R.

[0028] As in Figure 1 As shown in FIG, the rotor R according to the invention can be fastened to a motor shaft W. A worm S of a worm gear can also be fastened to the shaft, which transmits the movement of the motor shaft W and the rotor to another component.

[0029] Reference Signs List

[0030] 1 rotor core

[0031] 11 stacks

[0032] 111 inside

[0033] 1111 inner protruding section

[0034] 1112 inner recessed section

[0035] 112 outside

[0036] 1121 The protruding section on the outside

[0037] 1122 outer recessed section

[0038] 2 permanent magnets

[0039] 21 Inner surface of permanent magnet

[0040] 22 The outer surface of the permanent magnet

[0041] 23 Recessed part of permanent magnet

[0042] 3 plastic parts

[0043] 31 plastic parts 31

[0044] 311 Inner surface of component 31

[0045] 312 outer surface of component 31

[0046] 32 radially outwardly extending convex portion

[0047] 331 inwardly extending flange

[0048] 332 outwardly extending flange

[0049] 3321 convex portion of the outwardly extending flange

[0050] R rotor

[0051] S worm

[0052] W motor shaft

Claims

1. A rotor (R), in particular a rotor for a brushless DC motor, comprising a substantially hollow-cylindrical permanent magnet (2) and a substantially hollow-cylindrical rotor core (1) consisting of at least one laminated core arranged in the permanent magnet (2), characterized in that: The rotor (R) has a substantially hollow-cylindrical plastic component (3) which is arranged between the rotor core (1) and the permanent magnets (2).

2. The rotor (R) according to claim 1, characterized in that The rotor core (1) has concave portions and / or convex portions on the outer side.

3. The rotor (R) according to any one of claims 1 or 2, characterized in that The plastic component (3) has recesses and / or projections on the inner side.

4. Rotor (R) according to claims 2 and 3, characterized in that The convex portion of the rotor core (1) has a shape complementary to the concave portion of the plastic component (3), and / or the concave portion of the rotor core (1) has a shape complementary to the convex portion of the plastic component (3), and the convex portion of one component is engaged in the concave portion of the other component.

5. The rotor (R) according to any one of claims 1 to 4, characterized in that The plastic component (3) has recesses and / or projections at its end face or on the outer side.

6. A rotor (R) according to any one of claims 1 to 5, characterized in that The permanent magnet (2) has projections and / or recesses at its end faces or on its inner side.

7. The rotor (R) according to claim 5 or 6, characterized in that The convex portion of the plastic component (3) has a shape complementary to the concave portion of the permanent magnet (2), and / or the concave portion of the plastic component (3) has a shape complementary to the convex portion of the permanent magnet (2), and the convex portion of one component is engaged in the concave portion of the other component.

8. Method for producing a rotor (R) according to any one of claims 1 to 7, characterized in that The steps are as follows: • placing the permanent magnet (2) in an injection mold, • arranging the rotor core (1) in the injection mold in such a way that there is a spacing between the outer side of the rotor core and the inner side of the permanent magnets (2), so that a cavity is formed between the outer side of the rotor core, the inner side of the permanent magnets (2) and one or more walls of the injection mold, • closing the injection mold if necessary, and • Liquid plastic is injected into the cavity.

9. A motor, in particular a brushless DC motor, comprising a stator and a rotor (R), characterized in that The rotor is a rotor (R) according to any one of claims 1 to 7. 10 . An actuator, in particular for use in a vehicle, comprising a rotor (R) according to claim 1 .

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