DE102022116139A1 - Rotor for an electrical machine and method for producing the same - Google Patents

Abstract

The invention provides a rotor (10) for an electrical machine with the following features: The rotor (10) carries an outer magnet (15) and a bandage (11) spanning the outer magnet (15); and the rotor (10) has a pretensioning element (20) arranged radially below the outer magnet (15) for tightening the bandage (11). The invention further provides a corresponding manufacturing method, a corresponding electrical machine and a corresponding motor vehicle.

Description

The present invention relates to a rotor for an electrical machine. The present invention also relates to a corresponding manufacturing method, a corresponding electrical machine and a corresponding motor vehicle.

State of the art

IEC 60034-16-1 standardizes different types of excitation for single-phase and three-phase synchronous machines. According to the state of the art, synchronous machines of small to medium power, such as those used as servo motors in vehicle technology, are predominantly permanently excited (permanently excited synchronous machine, PSM). The magnets used for this can be applied to or inserted into the laminated cores of the rotor in a variety of ways.

What is well known are superficially attached and embedded (“buried”) magnets, which are often arranged in a star shape in the rotor to concentrate the flux. In order to further increase the flux density in the air gap, rare earth magnets in particular are often arranged in a V-shape under a pole. In the pursuit of a compromise between the lowest possible magnetic edge scatter and manageable tensile and shear stresses, both configurations are sometimes combined.

To secure the surface magnets of rapidly rotating rotors, they usually have reinforcement that absorbs the centrifugal force acting on the magnets during operation. In high-performance engines, thin-walled bandages made of fiber-reinforced plastic are used instead of metallic sleeves in order to avoid eddy currents in the reinforcement.

In the design and manufacture of bandaged rotors, a deliberately defined overlap of the laminated core and rotor bandage components is required with regard to operational functionality.

The bandage must therefore always be “tightened” for operation under all load spectrums.

According to the state of the art, the required preload is achieved by a geometric transition to press fit. The overlap between the laminated core and the bandage is typically less than 1 percent of the rotor diameter.

This makes the joining process a challenge, as the components inevitably have to be joined below ambient temperature or under contact (with high demands on the respective surfaces) for damage-free and contactless assembly. For this purpose, the laminated core is cooled strongly - for example with nitrogen - and its outer surface is finely ground.

US2014009024A1 discloses a rotor of an electric motor, wherein the rotor has a rotor base body, a plurality of magnets arranged on an outer peripheral surface of the rotor base body, and a bandage.

DE102004046440A1 discloses a rotor of an electric motor, with a rotor base body, a plurality of magnets arranged on an outer peripheral surface of the rotor base body and a bandage, wherein a clamping device is provided for aligning the rotor base body on a rotor shaft.

US2016028282A1 discloses a rotor of an electric motor, wherein the rotor has a rotor base body, a plurality of magnets arranged on an outer peripheral surface of the rotor base body and a bandage, an end element being arranged at at least one axial end of the rotor base body, which is arranged radially between the bandage and an edge magnet.

DE10216856A1 discloses a rotor of an electric motor, wherein the rotor has a rotor base body, a plurality of magnets arranged on an outer circumferential surface of the rotor base body and a bandage, a locking ring being provided in each case for fixing the two axial ends of the bandage.

Disclosure of the invention

The invention provides a rotor, a method for producing the same, an electrical machine and a motor vehicle according to the independent claims.

The invention is based on the idea of providing a generic rotor with additional components or additional geometric features on existing components to generate the radial preload.

This approach gives rotors according to the invention high operational stability and speed.

Further advantageous embodiments of the invention are specified in the dependent claims. The components in question can either already be present as punched tabs or other spring elements on the components used or additionally radially or axially Elements introduced are introduced as part of pre- or post-processing during assembly.

One advantage of this approach is the reduction of complex pre-processes - such as grinding the outer diameter of the rotor lamination stacks - and cold-hot processes in production. Rather, the production of a rotor according to the invention is achieved sustainably through resource-saving processes.

Brief description of the drawings

• 1 zeigt den Stand der Technik.
• 2 zeigt erfindungsgemäße Ausprägungen an vorhandenen Bauteilen.
• 3 zeigt erfindungsgemäße Zusatzbauteile zum Einsetzen vor, während oder nach der Montage.

Embodiments of the invention are shown in the drawings and are described in more detail below.

• 1 shows the state of the art.
• 2 shows characteristics of the invention on existing components.
• 3 shows additional components according to the invention for insertion before, during or after assembly.

Embodiments of the invention

1 shows the segment of a bandaged rotor (10) in its cross section, which is composed of an inner (12) and outer laminated core (14), which embed two magnets (13) aligned at an obtuse angle to one another and symmetrically to the rotor radius. Together, the magnets (13) describe the shape of the letter “V”, so to speak. The outer laminated core (14) also carries an outer magnet (15), which in turn is spanned by the bandage (11) of the rotor (10).

The term “bandage” should be interpreted in a broad sense, which includes reinforcements wound directly on the rotor (10) as well as inherently strong components for fixing the loose outer laminated core (14) and magnets (15). If this bandage (11) is not tight on the rotor (10), there is insufficient strength and it will fail when it rotates quickly, as the illustration clearly shows. Such a component design presents the expert with the challenge of generating a pre-tension in the bandage (11).

2 illustrates the corresponding segment of a rotor (10) according to the invention, which faces this challenge. For this purpose, the electrical sheets of the laminated cores (12, 14) were cut or punched by laser during production in such a way that they each have a tab (20) on their surface facing the inner magnet (13), which is received by a corresponding groove in the same . The tabs (20) shown here in the unstressed state after punching or cutting are tensioned during assembly so that they tighten the bandage (11) via the inner magnet (13) after final assembly.

3 highlights a modification of this principle, in which instead of the molded tabs (20 - 2 ) a wedge (20) manufactured independently of the laminated cores (12, 14) serves as a prestressing element, which - pointing radially outwards with respect to the rotor (10) and thus in the direction of the outer magnet (15) - in the cavity between the inner magnets ( 13) and is therefore located at the apex of the letter “V” formed by the latter. Such a wedge (20) can either be inserted during assembly or subsequently inserted along the rotor (10) into its cavity without departing from the scope of the invention.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2014009024 A1 [0009]
• DE 102004046440 A1 [0010]
• US 2016028282 A1 [0011]
• DE 10216856 A1 [0012]

Claims (10)

Rotor (10) for an electrical machine, characterized by the following features: - the rotor (10) carries an outer magnet (15) and a bandage (11) spanning the outer magnet (15) and - the rotor (10) has a radial pretensioning element (20) arranged below the outer magnet (15) for tightening the bandage (11). Rotor (10). Claim 1 , characterized by the following features: - the rotor (10) comprises an inner laminated core (12) and an outer laminated core (14), - the rotor (10) contains an inner magnet (13) aligned along a secant of its cross section and - the inner Magnet (13) is embedded between the laminated cores (12, 14) in such a way that the prestressing element (20) acts on the bandage (11) via the inner magnet (13). Rotor (10). Claim 2 , characterized by the following features: - the prestressing element (20) is a tab (20) on the inner (12) or outer laminated core (14) and - the inner magnet (13) has a groove for receiving the tab (20). Rotor (10). Claim 2 , characterized by the following features: - the rotor (10) contains a further inner magnet (13), - the inner magnets (13) are aligned at an obtuse angle to one another, - the rotor (10) has a magnet extending between the inner magnets (13). Cavity on and - the biasing element (20) is a wedge (20) directed towards the outer magnet (15) within the cavity. Rotor (10). Claim 4 , characterized by the following features: - the inner magnets (13) are aligned symmetrically to a radius of the cross section and - the wedge (20) points in the direction of the radius. Method for producing a rotor (10) according to one of Claims 2 until 5 , characterized by the following features: - Electrical sheet metal is cut or punched and assembled into the laminated cores (12, 14) and - the laminated cores (12, 14) and magnets are assembled and reinforced with the bandage (11). Procedure according to Claim 6 , characterized by the following features: - the prestressing element (20) is formed when cutting or punching on the electrical sheet and - the prestressing element (20) is tensioned during assembly. Procedure according to Claim 6 , characterized by the following features: - the prestressing element (20) is manufactured independently of the laminated cores (12, 14) and - the prestressing element (20) is inserted during assembly or inserted lengthwise into a cavity of the rotor (10) that remains after assembly. Electric machine with a rotor (10) according to one of the Claims 1 until 5 . Motor vehicle with an electric machine Claim 9 .

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