DE102019115737A1 - Method for mounting a rotor shaft for an electric motor - Google Patents

Abstract

The invention relates to a method for assembling a rotor shaft (1) for an electric motor, and comprises the steps of: a) positioning a laminated core (2) on the rotor shaft (1), b) positively locking the laminated core (2) to the rotor shaft (1 ) by hydroforming.

Description

The invention relates to a method for mounting a rotor shaft for an electric motor, a rotor shaft and an electric motor.

The US20170241471A1 discloses the mounting of a shaft for a vehicle.

1. a) Positionierung eines Blechpaketes auf der Rotorwelle;
2. b) Formschlüssiges Verbinden des Blechpakets mit der Rotorwelle durch Hydroforming.

The method according to the invention for mounting a rotor shaft for an electric motor comprises the steps:

1. a) positioning a laminated core on the rotor shaft;
2. b) Form-fitting connection of the laminated core to the rotor shaft by hydroforming.

In hydroforming, a metallic hollow body is deformed by a pressure which is generated in the hollow body. By forming a positive fit of the hollow body is achieved to a defined outer shape, which is positioned adjacent to the outer wall of the hollow body. The pressure is achieved by a liquid which is introduced into the interior of the hollow body for this purpose.

The laminated core comprises individual, stacked sheets. The sheets have at least partially a magnetic material. The individual sheets are separated by a separating layer. Thus, an adaptation of the magnetic properties of the sheet metal Pakt, which allows an optimization of the operation of the electric motor. The release layer comprises a lacquer, an adhesive and / or another, non-magnetic material. The sheets have an inner diameter with which they are positioned adjacent to the rotor shaft on this.

In electric motors, in particular in electric motors, which are used in electrically operated and / or partially electrically operated vehicles, a low weight of the rotor shaft is desirable. At the same time a positive connection between the rotor shaft and a laminated core is essential, as this connection, a transmission of torque takes place, which allows safe and long-lasting operation of the electric motor.

The inventive method allows the use of a hollow body as a rotor shaft. This allows a weight reduction of the rotor shaft, as well as an increase in the efficiency during operation of the electric motor.

In addition, cooling of the rotor shaft is made possible by the use of the hollow body, without the need for an additional long bore. This would be required in the event that the rotor shaft would be made of a solid material. Thus, a reduction of the manufacturing cost is made possible.

A rotor shaft according to the invention is mounted by a method according to the invention.

An electric motor according to the invention comprises a rotor shaft according to the invention.

The advantageous weight reduction of the rotor achieved by the method according to the invention and the reduction of the production costs and material costs of the rotor shaft are also advantageously produced for the electric motor according to the invention.

The dependent claims describe further advantageous embodiments of the invention.

• 1 eine Seitenansicht einer erfindungsgemäßen Rotorwelle 1 mit einem Blechpaket 3, und
• 2 einen Querschnitt durch ein Blech aus der ersten Anzahl an Blechen 3, und
• 3 eine Seitenansicht einer Rotorwelle 1 mit.

Preferred embodiments will be explained in more detail with reference to the following figures. It shows

• 1 a side view of a rotor shaft according to the invention 1 with a laminated core 3 , and
• 2 a cross section through a sheet of the first number of sheets 3 , and
• 3 a side view of a rotor shaft 1 With.

1 shows a side view of a rotor shaft according to the invention 1 , The rotor shaft 1 is mounted by a method according to the invention.

1. a) Positionierung eines Blechpaketes 2 auf der Rotorwelle 1;
2. b) Formschlüssiges Verbinden des Blechpakets 2 mit der Rotorwelle 1 durch Hydroforming.

The inventive method for mounting a rotor shaft 1 for an electric motor includes the steps:

1. a) positioning a laminated core 2 on the rotor shaft 1 ;
2. b) positive connection of the laminated core 2 with the rotor shaft 1 by hydroforming.

The rotor shaft 1 is pronounced as a tube, wherein the tube has a wall thickness and a pipe diameter, and wherein the wall thickness is between 5% and 30% of the pipe diameter.

By using a thin-walled tube, the weight reduction of the shaft is increased over full metal shafts and thick-walled tubes. It eliminates complex manufacturing steps, such as a subsequent long hole drilling to achieve a weight reduction in a full metal shaft. Furthermore, such a larger volume for a cooling liquid is available, which through the rotor shaft 1 can be directed. This allows an increase in the maximum possible cooling capacity. In addition, a faster heat dissipation through the thin-walled tube is made possible, which leads to a further effective increase in cooling capacity.

By choosing the wall thickness in a range between 5% and 30% of the pipe diameter, the stability and longevity of the rotor shaft 1 and the electric motor is not affected. In this embodiment, the diameter of the tube is 30 mm. After hydroforming, the diameter of the rotor shaft is between 30 mm and 50 mm.

In this embodiment, in step a) two end plates 4 on the rotor shaft 1 positioned, with the end plates 4 adjacent to the laminated core 2 positioned.

The use of the end plates 4 increases the stability of the laminated core 2 on the rotor shaft 1 ,

Conventionally, these end plates are provided with a clamping device to hold the laminated cores compressed and / or fixed with screws, resulting in an increase in weight and an increase in the production cost. Advantageously, the assembly of the end plates 4 therefore in the same step as the assembly of the laminated core 2 , This enables a positive and simple assembly without additional mounting material.

In this embodiment, the laminated core comprises 2 a first number of sheets 3 , wherein the sheets of the first number of sheets 3 be shaped by punching with a die.

In this embodiment, all sheets from the first number of sheets 3 shaped with an identical die. On the one hand, this makes it possible to reduce the production costs, since only one stamping mold has to be provided. In addition, it allows a simplification in the work processes of assembly, since the sheets of the first number of sheets 3 not sorted by shape on the rotor shaft 1 must be positioned.

The advantage of simplifying the work processes also results in the event that the sheets of the first number of sheets 3 be brought into shape by laser cutting and / or water cutting.

2 shows a cross section through a sheet of the first number of sheets 3 , The sheet has an inner diameter 6 on, with the inside diameter 6 three grooves 7 has, which are arranged symmetrically.

The sheets have at least partially a magnetic material in this embodiment. To adapt the properties of the electric motor, the sheets of the first number of sheets 3 each rotated by a first angle on the rotor shaft 1 positioned.

By using hydroforming, it is not necessary for the sheets to have correspondingly twisted grooves. This would require different dies, which would make production more costly. By hydroforming the grooves 3 positive fit with the rotor shaft 1 connected. In addition, such a simplified transfer of torque between the rotor shaft 1 and laminated core 3 allows.

3 shows a side view of the rotor shaft 1 after carrying out the method according to the invention. The rotor shaft has an outer diameter 8th on, with the outside diameter 8th at least one groove and / or a spring 5 having.

This results in springs 5 in the places where the sheets grooves 7 respectively. By step b) results in a shape transfer between the rotor shaft 1 and the laminated core 2 , In the event that the sheets have a spring, resulting in the rotor shaft corresponding to a groove.

In addition, in step a) slip rings, bearings, position encoders, bearing seats and / or gears on the rotor shaft 1 positioned.

This allows a simplification of the assembly of these components. It eliminates additional mounting materials, as well as additional installation costs.

An electric motor according to the invention, not shown, comprises a rotor shaft according to the invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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 20170241471 A1 [0002]

Claims (10)

Method for mounting a rotor shaft (1) for an electric motor, comprising the steps: a) positioning a laminated core (2) on the rotor shaft (1); b) positive connection of the laminated core (2) with the rotor shaft (1) by hydroforming. Method according to Claim 1 wherein the rotor shaft (1) is formed as a tube, and wherein the tube has a wall thickness and a tube diameter, and wherein the wall thickness is between 5% and 30% of the tube diameter. Method according to one of the preceding claims, wherein in step a) at least one end plate (4) on the rotor shaft (1) is positioned, and wherein the end plate (4) adjacent to the laminated core (2) is positioned. Method according to one of the preceding claims, wherein the laminated core (2) comprises a first number of sheets (3), and wherein the sheets of the first number of sheets (3) are shaped by punching with a punching die. Method according to one of the preceding claims, wherein the sheets of the first number of sheets (3) each have an inner diameter (6), and wherein the inner diameter (6) at least one groove (7) and / or a spring. Method according to one of the preceding claims, wherein the rotor shaft (1) has an outer diameter (8), and wherein the outer diameter (8) has at least one groove and / or a spring (5). Method according to one of the preceding claims, wherein in step a) slip rings, bearings, position encoders, bearing seats and / or gears are positioned on the rotor shaft (1). Method according to Claim 7 , Wherein the sheets of the first number of sheets (3) are each rotated by a first angle on the rotor shaft (1) are positioned. Rotor shaft (1), mounted by a method according to one of Claims 1 to 8th , Electric motor, comprising a rotor shaft (1) according to Claim 9 ,

Images