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DE-102024132604-A1 - Stator for an electric machine, in particular for an electric radial flux machine

DE102024132604A1DE 102024132604 A1DE102024132604 A1DE 102024132604A1DE-102024132604-A1

Abstract

The invention relates to a stator (1) for an electric machine (2), in particular for an electric radial flux machine, comprising a hollow cylindrical stator body (3) with a plurality of annular stator segments (4) with axially extending stator slots (25) in which an energizable stator winding (26) is inserted, wherein a rotor (6) is rotatably mounted in the stator body (3) forming an annular air gap (5), wherein the stator segments (4) are coupled to one another by means of a gear arrangement (7) and can be displaced in a radial and/or circumferential direction via the gear arrangement (7) so that the height of the air gap (5) is adjustable during operation of the electric machine (2).

Inventors

  • Matthias Dienst
  • Pascal Czygan
  • Johannes Kolb
  • Dominik Krahe
  • Roman Weisenborn
  • Pascal Strasser
  • Michael Stadtmüller
  • Martin Loth

Assignees

  • Schaeffler Technologies AG & Co. KG

Dates

Publication Date
20260513
Application Date
20241108

Claims (14)

  1. Stator (1) for an electric machine (2), in particular for an electric radial flux machine, comprising a hollow cylindrical stator body (3) with a plurality of annular stator segments (4) with axially extending stator slots (25) in which an energizable stator winding (26) is inserted, wherein a rotor (6) is rotatably mounted in the stator body (3) forming an annular air gap (5), characterized in that the stator segments (4) are coupled to each other by means of a gear arrangement (7) and can be displaced in a radial and/or circumferential direction via the gear arrangement (7) so that the height of the air gap (5) is adjustable during operation of the electric machine (2).
  2. Stator (1) after Claim 1 , characterized in that each stator segment (4) has an associated geared adjustment mechanism (8).
  3. Stator (1) after Claim 2 , characterized in that the geared adjustment mechanisms (8) of the stator segments (4) are essentially identical.
  4. Stator (1) according to one of the preceding claims, characterized in that the gear arrangement (7) has a synchronizing device (9) by which the kinematics of the adjustment mechanisms (8) of the stator segments (4) are synchronized with each other.
  5. Stator (1) according to one of the preceding claims, characterized in that the geared adjustment mechanism (8) comprises a rocker element (10) coupled to a stator segment (4), with at least one roller raceway (11) on which at least one roller (12) is guided to roll, and the adjustment mechanism (8) further comprises a roller guide element (13) fixed in a rotationally fixed manner relative to the stator (1) with a roller raceway (14) on which the roller (12) rolls relative to the roller guide element (13), wherein the roller raceway (11) of the rocker element (10) and the roller raceway (14) of the roller guide element (13) are configured such that the stator segment (4) can be displaced in a radial and/or circumferential direction.
  6. Stator (1) according to one of the previous Claims 4 - 5 , characterized in that the synchronization device (9) comprises a ring (27) to which the rocker elements (10) of the stator segments (4) are fixed in the circumferential direction.
  7. Stator (1) according to one of the preceding claims, characterized in that the stator segment (4) has a cylindrical ring segment-shaped cooling body (15) through which a cooling fluid can flow, which is in contact with the outer surface (16) of the stator segment (4).
  8. Stator (1) according to one of the preceding claims, characterized in that a spring element (17), in particular a leaf spring, is arranged in the circumferential direction between two adjacent stator segments (4).
  9. Stator (1) according to one of the previous Claims 7 - 8 , characterized in that the spring element (17) rests against the circumferentially adjacent cooling elements (15) of the stator segments (4).
  10. Stator (1) according to one of the previous Claims 1 - 7 , characterized in that the spring element (17) is in particular designed as a bow spring which is supported on one side against a stator segment (4) and on the other side against the motor housing (38).
  11. Stator (1) according to one of the preceding claims, characterized in that a stop means (20) is provided which defines at least a first end position (21) and preferably also a second end position (22) of the stator segment (4).
  12. Stator (1) after Claim 11 , characterized in that an axially extending groove (19) is formed on the outer surface (18) of the stator segment (4) and/or the heat sink (15), into which the stop element (20) which is designed to be rotationally fixed relative to the stator (1) engages, so that a first end position (21) of the stator segment (4) and a second end position (22) of the stator segment (4) are defined by the circumferential stops of the stop element (20) in the groove (19).
  13. Stator (1) according to one of the previous Claims 4 - 7 , characterized in that the gear arrangement (7) is coupled to a drive (23) and the gear arrangement (7) can be actuated by external force.
  14. Stator (1) after Claim 13 , characterized in that the synchronizing device (9) of the gear arrangement (7) is coupled to the drive (23).

Description

The present invention relates to a stator for an electric machine, in particular for an electric radial flux machine, comprising a hollow cylindrical stator body with a plurality of annular stator segments with axially extending stator slots in which an energizable stator winding is inserted, wherein a rotor can be rotatably mounted in the stator body forming an annular air gap. Developments in the field of permanent magnet synchronous machines are characterized, among other things, by the challenge of optimizing the air gap between the rotor and stator to maximize both machine efficiency and torque density. Conventional solutions often use fixed stators or simple mechanical adjustment devices that can adapt the air gap to a limited extent. However, in many known systems, the air gap between the rotor and stator is dimensioned statically, leading to suboptimal efficiency, especially in operating cycles with frequently changing load conditions. A common problem with fixed stators is their inability to adequately resolve the trade-off between high efficiency at partial load and high power density at full load. A fixed air gap is typically a compromise, designed for either high power or high efficiency, but not optimizing both equally. This leads to unnecessarily high iron losses at low loads because the magnetic flux in the machine cannot be reduced. Simultaneously, at high loads, the fixed air gap limits efficiency, as the magnetic coupling between the rotor and stator cannot be maximized. Another well-known concept is the use of movable stators or rotors, where the air gap is changed by mechanical adjustment. However, such systems often require complex and expensive mechanisms, implemented with a multitude of components and moving parts. Maintaining mechanical stability and precise air gap positioning during operation is particularly challenging with axially movable stators or rotors. Uneven air gaps can lead to torque irregularities, impairing machine performance and increasing wear. Furthermore, many of these systems require the air gap to be adjusted either manually or indirectly via motor torque, which severely limits the flexibility of machine control. With these solutions, the air gap is often only adjustable to two end positions – a maximum and a minimum air gap. This restricts the ability to dynamically adapt the air gap to different operating conditions, which can lead to suboptimal efficiency, particularly during rapid load changes and in deceleration (recuperation) operation. Another problem with existing systems is that they often rely on mechanical spring elements to move the air gap into one of its two end positions. This not only makes the machine design more susceptible to mechanical wear but also complicates precise control of the air gap in intermediate positions. Furthermore, such mechanical components increase the system's complexity and make it more maintenance-intensive. Overall, the known methods for adjusting the air gap are limited in their flexibility and efficiency. They either require complex mechanical structures, which increase production effort and costs, or offer only limited control options that are unable to dynamically adapt the air gap to the respective operating conditions of the machine. It is therefore the object of the present invention to provide a stator that avoids or at least reduces the problems known from the prior art. This problem is solved by a stator for an electric machine, in particular for an electric radial flux machine, comprising a hollow cylindrical stator body with a plurality of annular stator segments with axially extending stator slots in which an energizable stator winding is inserted, wherein a rotor can be rotatably mounted in the stator body forming an annular air gap, wherein the stator segments are coupled to each other by means of a gear arrangement and can be displaced in a radial and/or circumferential direction via the gear arrangement, so that the height of the air gap can be adjusted during operation of the electric machine. This stator offers the advantage of flexibly adjusting the air gap between the rotor and stator of an electric machine during operation. This enables precise control of the magnetic flux, which improves the machine's efficiency in the partial load range and optimizes performance at higher loads. Furthermore, the adjustability of the stator segments reduces the Iron losses are reduced because the air gap can be enlarged when less magnetic flux is required, without significantly increasing copper losses. Mechanical adjustment of the air gap allows for field-weakening operation without the need for additional power components, resulting in overall higher efficiency and improved energy consumption of the machine. For the purposes of this patent application, the phrase "the stator segments are coupled to one another by means of a gear arrangement" means that the stator segments are interconnected by an arrangement that