The present invention refers to a stator for an electric machine and to a process for manufacturing such a stator. In particular, the invention refers to a stator for a rotating electric machine with open or closed slots comprising a winding made using a metal conductor.
Known electric machines include a fixed part, the stator, and a moving part, the rotor, arranged coaxially one inside the other. Typically, the rotor comprises a pack of laminations fixed on a rotation shaft, and is inserted inside the stator, which includes an electric winding capable of generating a magnetic field that causes the rotor to rotate.
The stator is generally annular in shape and includes a plurality of radial slots, inside which the electric winding is obtained.
Electric machines are known, for example a synchronous reluctance electric motor assisted by permanent magnets, comprising a stator with open slots; also known are electric machines with a stator with closed slots which provides a wall for closing the stator slots at the rotor, to reduce the problems caused by the torque ripple, with the vibrations and noise associated therewith.
For making the electric windings of the stators, it is known to use electric conductors made using strips or continuous wires, or copper strips that are bent in the central part to form hairpin-shaped strips, to be inserted in the stator slots.
In known stators, both with open slots and with closed slots, there is a need to optimize efficiency and operation of the electric machine in a desired operating condition, for example with a certain direction of rotation of the rotor.
Object of the present invention is solving these problems by means of a stator for an electric machine, which allows improving the efficiency and operation of the electric machine in a desired operating condition, without complicating the production process.
The aforementioned and other objects and advantages of the invention, which will appear from the following description, are achieved with a stator for an electric machine and a process for the construction of such a stator as described in the independent claims.
Preferred embodiments and non-trivial variants of the present invention are the subject matter of the dependent claims.
It is understood that all attached claims form an integral part of the present description.
It will be immediately obvious that innumerable variations and modifications (for example relating to shape, dimensions, arrangements and parts with equivalent functionality) can be made to what is described, without departing from the scope of the invention as appears from the attached claims.
The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the attached drawings, in which:
With reference to the figures, the stator 15 for an electric machine according to the invention will be described below, and comprises an external annular portion 35 and an internal portion 25, delimited by a cylindrical internal wall 32 of the stator 15 which is configured to house a rotor 5, the internal portion 25 comprising a plurality of slots 14, 24 inside which the electric winding is made, arranged along the direction of a longitudinal Y axis of the stator 15, spaced by a space 27, at least one of the slots 14, 24 having an asymmetrical conformation; preferably, each of the slots 14, 24 has an asymmetrical conformation; preferably, the Y axis is the longitudinal, central axis of symmetry of the stator 15.
In particular, the slot 14, 24 has an asymmetrical conformation with respect to a plane R passing through the longitudinal Y axis of the stator 15 and through a centreline P of the slot 14, 24 in correspondence with the internal wall 32.
The slot 14, 24 of the stator 15 comprises two side walls 42 made in the internal portion 25 of the stator, and an upper wall 40 made in the external annular portion 35.
In a preferred embodiment of the invention, the side walls 42 of the slot 14, 24 are asymmetrical, in particular with respect to the plane R passing through the longitudinal Y axis of the stator 15 and the centreline P of the slot 14, 24 at the inner wall 32; preferably, the side walls 42 of the slot 14, 24 are curved or concave, and more preferably have the concavity made in such a way as to optimize the efficiency or operation of the electric machine in a desired operating direction; for example, the concavity faces in a specific direction with respect to a preferred rotation direction Z of the rotor 5. The stator 15 of the invention preferably comprises a continuous winding made with a strip 11 or a wire inserted inside the slots 14, 24.
In a first embodiment of the invention, the stator 15 comprises a plurality of closed slots 14 arranged, preferably equidistant from each other, along the cylindrical internal wall 32 of the stator 15, and each slot 14 comprises a bottom wall 38 arranged along the direction of the longitudinal Y axis of the stator 15, in proximity to the internal wall 32 at a distance E from the internal wall 32.
Each closed slot 14 of the stator 15 is composed of two side walls 42 and of a bottom wall 38 made in the internal portion 25 of the stator, and of an upper wall 40 made in the external annular portion 35; for example, the bottom wall 38 has a semi-circular or arched shape.
These closed slots 14 have an asymmetrical conformation with respect to a plane R passing through the Y axis and the centreline P of the bottom wall 38.
The stator 15 with closed slots according to the first embodiment of the invention preferably comprises a plurality of longitudinal teeth 26 made in the internal portion 25 of the stator, spaced apart by a space 27 configured to form the lower part of the closed slots 14, and a plurality of seats 36 made in the outer annular portion 35, complementary to the teeth 26 and configured to fit together with the inner portion 25 of the stator by means of a reciprocal sliding movement of the inner portion 25 and of the outer annular portion 35, in order to form the closed slots 14 and stator 15.
Preferably, each closed slot 14 of the stator 15 according to the first embodiment of the invention is composed of two side walls 42 of two adjacent teeth 26 made in the internal portion 25 of the stator, of the bottom wall 38 connecting the two adjacent teeth 26 and of an upper wall 40 formed by a wall for connecting two adjacent seats 36 made in the outer annular portion 35 of the stator.
The stator 15 with closed slots according to the first embodiment of the invention preferably comprises a continuous winding made with a strip 11 or a wire inserted inside the closed slots 14 of the stator 15, preferably wrapping the strip 11 on the teeth 26 by means of a relative rotation of the internal portion 25 with respect to the strip 11.
In the first embodiment of the stator 15 with closed slots according to the invention, the external annular portion 35 of the stator is composed of interlocked sectors, for example by providing a guide that allows the sectors to be assembled by sliding them in the direction of the Y axis longitudinal stator 15.
The process for making a closed-slot stator with continuous winding according to the first embodiment of the invention includes the following steps:
In a second embodiment of the invention shown in
Each open slot 24 of the stator 15 is formed by two side walls 42 made in the internal portion of the stator, by an opening 48 and by an upper wall 40 made in the external annular portion 35.
The open slots 24 have an asymmetrical conformation with respect to a plane R passing through the Y axis and the centreline P of the opening 48 in correspondence with the internal wall 32.
The stator 15 with open slots according to the second embodiment of the invention preferably comprises a plurality of longitudinal teeth 26 made in the internal portion 25 of the stator, spaced from a space configured to make the open slots 24.
Preferably, each open slot 24 of the stator 15 according to the second embodiment of the invention is composed of two side walls 42 of two adjacent teeth 26 made in the internal portion 25 of the stator, and of an upper wall 40 formed by a wall of connection of two adjacent teeth 26.
The stator 15 with open slots according to the second embodiment of the invention preferably comprises a continuous winding made with a strip 11 or a wire inserted inside the open slots 24 of the stator 15, preferably by wrapping the strip 11 on the teeth 26 by means of a relative rotation of the stator 15 with respect to the strip 11.
The process for making a stator with open slots with continuous winding according to the second embodiment of the invention includes the following steps:
Advantageously, the stator for a rotating electric machine with open or closed slots according to the invention makes it possible to facilitate the insertion of the winding in the stator slots to fill them in an optimal way, and to optimize the efficiency and operation of the electric machine in a desired operating condition, for example with a certain direction of rotation of the rotor.
Filing Document | Filing Date | Country | Kind |
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PCT/IT2020/000089 | 12/31/2020 | WO |