Electric machine

Abstract

The invention relates to an electric machine (10) comprising: a stator unit (14) with a ferromagnetic stator body (18), a plastic holding body (24) surrounding the stator body (18), at least one stator winding (22) arranged on the plastic holding body (24), a rotor unit (16) with a rotor shaft (40), which is rotatably mounted on the plastic holding body (24) via a shaft radial bearing (25), and a rotor body (42) which is secured to the rotor shaft (40) and is arranged inside the stator body (18), with the plastic holding body (24) having two axially adjacent plastic holding elements (241, 242), and with the shaft radial bearing (25) being detachably secured to one of the plastic holding elements (241, 242) via an engaging connection.

Description

[0001] DESCRIPTION

[0002] Electric machine

[0003] The present invention relates to an electrical machine having a stator unit comprising a ferromagnetic stator body, a plastic holding body surrounding the stator body and at least one stator winding arranged on the plastic holding body, and a rotor unit comprising a rotor shaft rotatably mounted on the plastic holding body via a shaft radial bearing and a rotor body fastened to the rotor shaft and arranged within the stator body.

[0004] Such electrical machines are generally known from the prior art. For example, the stator body can be overmolded by the plastic retaining body. The radial shaft bearing is arranged on a separate bearing plate, with the radial shaft bearing being glued or caulked to the bearing plate. The disadvantage of such designs is that the manufacture of the plastic retaining body and the accommodation of the radial shaft bearing is complex and costly. When manufacturing the stator unit, the plastic retaining body must be inserted into the injection mold so that it can be overmolded. This significantly increases the complexity of the injection mold. In addition, a separate bearing plate must be manufactured and assembled, which increases the assembly effort.

[0005] The present invention is based on the object of creating a relatively cost-effective and easily assembled electrical machine. This object is achieved by an electrical machine having the features of main claim 1.

[0006] The electric machine according to the invention comprises a fixed stator unit and a rotatable rotor unit.

[0007] The stator unit comprises a ferromagnetic stator body and a multi-part plastic support body that surrounds the stator body. Typically, the stator body defines a plurality of stator poles distributed along a circumference of the rotor unit. The stator body can be designed as a solid body. However, the stator body preferably consists of a plurality of sheet metal parts. A stator body constructed in this way is also referred to as a laminated stator body or a laminated stator body and exhibits particularly low eddy currents during operation of the electrical machine. The stator body is generally made of a ferromagnetic metal. The stator body comprises at least one, typically several, winding support sections on which an electromagnetic stator winding is arranged.

[0008] The plastic holding body is preferably produced by an injection molding process and serves, among other things, to provide electrical insulation between the stator body and the stator windings, which is why at least a main section of the plastic holding body surrounding the stator body is preferably made of a plastic material with good electrical insulation properties, i.e. with a high specific electrical resistance, typically at least 10 10 Qcm, and a high dielectric strength.

[0009] The rotor unit comprises a rotor shaft, which is supported in the plastic support body via a radial shaft bearing, and a rotor body, which is attached to the rotor shaft and arranged within the stator body. The radial shaft bearing can be configured for exclusively radial support or can be configured for radial and axial support of the rotor shaft. Typically, the rotor shaft is supported in a housing part of the electric machine via another radial shaft bearing, which is arranged on a side of the rotor body opposite the radial shaft bearing arranged on the plastic support body.

[0010] The rotor body can be designed as a solid, permanent-magnetic body, can be configured to support at least one permanent magnet, or can be configured to support at least one electromagnetic rotor winding. In the latter two cases, the rotor body is generally made of a ferromagnetic metal and can be designed either as a solid body or consist of several interconnected individual parts, typically sheet metal parts.

[0011] According to the invention, the plastic retaining body has two axially adjacent plastic retaining elements, wherein the shaft radial bearing is detachably fastened to one of the plastic retaining elements via a snap-in connection. By dividing the plastic retaining body into two plastic retaining elements, the manufacture of the stator unit can be simplified, wherein the plastic retaining elements can be manufactured using relatively simple injection molds and subsequently fastened to the stator body in a simple assembly step, namely by sliding the plastic retaining elements onto the stator body. Furthermore, the manufacture of the stator unit is simplified by mounting the shaft radial bearing to the plastic retaining body via a snap-in connection.The radial shaft bearing simply needs to be inserted into an opening provided on the plastic retaining element. The inserted radial shaft bearing abuts axially against an inwardly projecting radial projection on the one hand and is held axially by a locking element, preferably in the form of a locking lug, on the other. This secures the radial shaft bearing in both axial directions.

[0012] In this way, the electrical machine according to the invention can be assembled relatively easily and manufactured relatively inexpensively.

[0013] The shaft radial bearing is preferably a rolling bearing, preferably a ball bearing. The rolling bearing has an inner ring, an outer ring, and a plurality of rolling elements arranged between the inner ring and the outer ring. For example, the inner ring is provided with a

[0014] inner peripheral surface on the rotor shaft of the rotor unit. The outer ring is fixed with an outer peripheral surface on the

[0015] Plastic retaining element is locked axially and supported radially with an outer peripheral surface on a bearing surface.

[0016] The plastic retaining body preferably has at least two axially spaced-apart parting planes, with both plastic retaining elements each having at least one first, short axial section and at least one second, long axial section, with the first axial section of the first plastic retaining element and the second axial section of the second plastic retaining element defining a first parting plane, and the first axial section of the second plastic retaining element and the second axial section of the first plastic retaining element defining a second parting plane. This ensures that, when the stator unit is subjected to torsional stress, there is no transverse plane along which the two plastic retaining elements exclusively slide in the circumferential direction.At the first parting plane, the two plastic retaining elements would slide against each other in the circumferential direction, but the two axial sections defining the second parting plane support the area of ​​the first parting plane in the direction of rotation. Likewise, the two plastic elements at the second parting plane support each other in the direction of rotation through the axial sections defining the first parting plane.

[0017] Preferably, the stator body has a plurality of radial projections distributed over the circumference, and the plastic retaining body has a radial opening for each radial projection, such that the plastic retaining elements are positively connected to the stator body in the circumferential direction by the engagement of the radial projections in the radial openings. This allows the plastic retaining body to be easily fastened to the stator body in the circumferential direction.

[0018] In a preferred embodiment, the first axial section is arranged in the circumferential direction on a first side of a radial projection and the second axial section is arranged on a second side of the

[0019] radial projection. In this way, the

[0020] Plastic retaining bodies are divided at each radial projection of the stator body in both parting planes, thus increasing the rigidity of the stator unit at each radial projection. Preferably, the same axial section of a plastic retaining element is arranged in the circumferential direction on the two mutually facing sides of the adjacent radial projections.

[0021] Preferably, one plastic retaining element has a section in the circumferential direction between two axial sections, which has a recess into which a projection of a section of the other plastic retaining element arranged in the circumferential direction between two axial projections engages. This creates an additional positive connection between the two plastic retaining elements, which further increases the torsional rigidity, i.e., the rigidity in the circumferential direction, of the stator unit.

[0022] Preferably, the plastic retaining elements are each made in one piece. This allows for simple and cost-effective production. The plastic retaining elements are preferably manufactured using an injection molding process.

[0023] In a preferred embodiment, the plastic retaining elements are axially secured to one another by the stator winding wound onto the plastic retaining body. The coil winding is wound around the sections of the plastic retaining elements in the area of ​​the radial projections, thereby axially securing the plastic retaining elements to one another. This allows the plastic retaining elements to be axially connected to one another easily and cost-effectively, eliminating the need for additional, cost-intensive joining elements.

[0024] Preferably, the plastic retaining elements are each pot-shaped, with the plastic elements each having a front end portion and a sheathing portion surrounding the base body. At least one of the plastic retaining elements has an opening on the front end portion through which the rotor unit can be pushed when the stator unit is fully assembled. Alternatively, the rotor unit could first be inserted into the through-opening of the stator unit, and then at least one of the two plastic retaining elements could be fully assembled. In this case, an opening for pushing the rotor unit through on one of the plastic retaining elements would not be required. An exemplary embodiment of the present invention is described below with reference to the accompanying figures. Herein:

[0025] Figure 1 is an exploded view of an electrical machine according to the invention,

[0026] Figure 2 is a perspective view of a fully assembled stator unit of an electrical machine from Figure 1, and

[0027] Figure 3 is a sectional view of the electrical machine from Figure 1.

[0028] Figures 1 and 3 show an electrical machine 10 with a stator unit 14, also shown in Figure 2, and a rotatable rotor unit 16.

[0029] The stator unit 14 comprises a stator body 18, which consists of a plurality of ferromagnetic sheet metal parts 181 stacked in the axial direction to form a laminated core 182. The stator body 18 comprises six radial projections 20 distributed over the circumference, which extend axially from a first end face to the second end face of the laminated core 182. Each radial projection 20 forms a winding support section 183, on which a stator winding 22 is arranged.

[0030] The stator unit 14 further comprises a plastic holding body 24, which is composed of a first plastic holding element 241 and a second plastic holding element 242. The plastic holding elements 241, 242 are each pot-shaped and have an end face section 26 and a covering section 28. Both plastic holding elements 241, 242 have

[0031] Enclosure section 28 has six radially projecting sections 29 distributed over the circumference, each of which includes an open radial opening 30. In the final assembled state, radial projections 20 of the stator body 18 are arranged within the radial openings 30 of the plastic holding elements 241, 242.

[0032] During assembly of the stator unit 14, the pot-shaped first plastic retaining element 241 is pushed onto the laminated core via the first end face of the stator body 18 with the enclosing section 28. The pot-shaped second plastic retaining element 242 is also pushed onto the laminated core 182 via the second end face of the stator body 18 with the enclosing section 28. In the final assembled state, the two plastic retaining elements 241, 242 abut or rest against one another with the axial end facing away from the end face section 26 and are axially connected to one another by the wound stator winding 22.

[0033] The plastic holding body 24 has two axially spaced-apart parting planes E1, E2, at which the two plastic holding elements 241, 242 axially adjoin or bear against one another. For this purpose, the two plastic holding elements 241, 242 each have six first, short axial sections 321, 341 and six second, long axial sections 322, 342, wherein the first axial sections 321, 341 all have the same length and the second axial sections 322, 342 also all have the same length. The first axial sections 321 of the first plastic holding element 241 and the second axial sections 342 of the second plastic holding element 242 define the first parting plane E1. The first axial sections 341 of the second plastic holding element 242 and the second axial sections 322 of the first plastic holding element 241 define a second parting plane E2. The total length of the two axially adjacent, ieaxial sections 321, 342 and 322, 341 of the two, which are arranged in alignment with one another.

[0034] The plastic retaining elements 241, 242 always remain the same. The axial sections 321, 322, 341, 342 are arranged in the circumferential direction on the radial projections 20 of the stator body 18 such that the first axial section 321, 341 is arranged on a first side of a radial projection 20 and the second axial section 322, 342 is arranged on a second side of the radial projection 20, wherein the same axial section 321, 322, 341, 342 is arranged on the sides of the adjacent radial projections 20 facing each other in the circumferential direction.

[0035] In addition, both plastic holding elements 241, 242 have a plurality of sections 36 in the circumferential direction between the two axial sections 321, 322, 341, 342, each of which has a recess 361 or a projection 362, wherein each projection 362 of a plastic holding element 241, 242 engages in a recess 361 of the other plastic holding element 241, 242.

[0036] The plastic holding elements 241, 242 are each made of a single plastic material which has relatively good electrical insulation properties.

[0037] The rotor unit 16 comprises a rotor shaft 40 and a rotor body 42 fastened to the rotor shaft 40. The rotor shaft 40 is rotatably mounted on a first axial side of the rotor body 42 via the shaft radial bearing 25, which is designed as a rolling bearing, in particular as a ball bearing, on the plastic holding body 24, in particular on the first plastic holding element 241. The shaft radial bearing 25 is arranged in an opening 260. The shaft radial bearing 25 is fastened to the rotor shaft 40 by an inner circumferential surface of an inner ring, on the one hand. The shaft radial bearing 25 is firmly connected to the first plastic holding element 241 by an outer circumferential surface of an outer ring. The shaft radial bearing 25 is supported radially with its outer circumferential surface on a bearing receiving surface 261 provided by the opening 260.In the axial direction, the shaft radial bearing 25 is held, on the one hand, by a plurality of radial projections 262 provided on the end face portion 26 and extending radially inward, and, on the other hand, by a plurality of locking elements 263 distributed over the circumference. The shaft radial bearing 25 rests with a first end face against the radial projections 262 and with a second end face against the locking elements 263. As a result, the shaft radial bearing is held axially on the first plastic retaining element 241 in a simple manner.

[0038] The rotor shaft 40 is rotatably mounted on a second axial side of the rotor body 42 via a further bearing element not shown in the figures on a housing (also not shown). Alternatively, the rotor shaft 40 could also be rotatably mounted on the plastic holding body 24, in particular on the second plastic holding element 242.

[0039] In this way, the electrical machine 10 according to the invention can be assembled relatively easily and manufactured relatively inexpensively.

Claims

Pierburg GmbH PATENT CLAIMS 1. Electrical machine (10), comprising: - a stator unit (14) with • a ferromagnetic stator body (18), • a plastic holding body (24) which surrounds the stator body (18), • at least one stator winding (22) which is arranged on the plastic holding body (24), - a rotor unit (16) with • a rotor shaft (40) which is rotatably mounted on the plastic holding body (24) via a shaft radial bearing (25), and • a rotor body (42) which is fastened to the rotor shaft (40) and is arranged within the stator body (18), characterized in that the plastic holding body (24) has two axially adjacent plastic holding elements (241, 242), wherein the Shaft radial bearing (25) is releasably attached to one of the plastic holding elements (241, 242) via a locking connection.

2. Electrical machine (10) according to claim 1, wherein the Shaft radial bearing (25) is a rolling bearing.

3. Electrical machine (10) according to claim 1, wherein the Shaft radial bearing (25) receiving plastic retaining element (241, 242) has an opening (260) in which the shaft radial bearing (25) is arranged, wherein the shaft radial bearing (25) is axially supported with a first end face against an inwardly projecting radial projection (262) of the plastic holding element (241, 242) and is held axially with a second end face by a locking element (263).

4. Electrical machine (10) according to claim 1 or 2, wherein the plastic holding body (24) has at least two axially spaced-apart parting planes (E1, E2), wherein both plastic holding elements (241, 242) each have at least a first, short axial section (321, 341) and at least a second, long axial section (322, 342), wherein the first axial section (321) of the first plastic holding element (241) and the second axial section (342) of the second plastic holding element (242) define a first parting plane (E1) and the first axial section (341) of the second plastic holding element (242) and the second axial section (322) of the first plastic holding element (241) define a second parting plane (E2).

5. Electrical machine (10) according to claim 1 or 2, wherein the stator body (18) has a plurality of radial projections (20) distributed over the circumference and the plastic holding body (24) has a radial opening (30) for each radial projection (20), such that the plastic holding elements (241, 242) are positively connected to the stator body (18) in the circumferential direction by the engagement of the radial projections (20) in the radial openings (30).

6. Electrical machine (10) according to claim 2 and 3, wherein the first axial section (321, 341) is arranged in the circumferential direction on a first side of a radial projection (20) and the second axial section (322, 342) is arranged on a second side of the radial projection (20).

7. Electrical machine (10) according to claim 4, wherein in the circumferential direction on the two mutually facing sides of the mutually adjacent radial projections (20) the same axial section of a plastic holding element (241, 242) is arranged.

8. Electrical machine (10) according to claim 5, wherein the one plastic holding element (241, 242) has a section (36) in the circumferential direction between two axial sections (321, 341, 322, 342), which section has a recess (361) into which a projection (362) of a section (36) of the other plastic holding element (241, 242) arranged in the circumferential direction between two axial sections (321, 341, 322, 342) engages.

9. Electrical machine (10) according to one of the preceding claims, wherein the plastic holding elements (241, 242) are each designed in one piece.

10. Electrical machine (10) according to one of the preceding claims, wherein the plastic holding elements (241, 242) are axially fastened to one another by the stator winding (22) wound onto the plastic holding body (24).

11. Electrical machine (10) according to one of the preceding claims, wherein the plastic holding elements (241, 242) are each pot-shaped, wherein the plastic holding elements (241, 242) each have an end face section (26) and a covering section (28) surrounding the stator body (18), wherein the shaft radial bearing is arranged on the end face section.

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