Displacement body for rotor and rotor formed therewith - Patent application

Abstract

To provide means for efficiently cooling a rotor winding.SOLUTION: Provided is a displacement body (20) for a rotor, wherein the displacement body (20) is configured to be inserted into a groove between two respective rotor teeth. The displacement body (20) has a main part (21), and a head part (22) adjoining the main part. The head part (22) has a region expanding toward the outside of the displacement body (22), and at least one cooling channel (25) which extends through the displacement body (20) in a depth direction. The displacement body (20) is formed as a laminate of layers having at least two adjoining layers (23, 24) in the depth direction. Moreover, a correspondingly configured rotor and a relevant electric motor are provided.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a displacer body for a rotor that is inserted into a groove in the rotor, and to a rotor formed thereby. [Background technology]

[0002] In separately excited synchronous machines (FAMs), the magnetic field in the rotor is generated by a current-carrying coil (electromagnet). The rotor magnetic flux can be variably adjusted by the excitation current flowing through the coil. The coil is often wound around a single pedestal.

[0003] To generate the strongest possible magnetic field in the rotor of a separately excited synchronous machine, the rotor winding must carry the highest possible current and have the most number of turns. To ensure the maximum number of turns is available in the installation space for the winding, the rotor winding is made of small-diameter round wire. To prevent this wire from slipping under the influence of centrifugal force, wedges are used to secure the winding, usually made of plastic.

[0004] In contrast to laminated cores for the rotor, the rotor windings experience a higher loss density, resulting in significantly higher temperatures than laminated cores. Therefore, the continuous power output of separately excited synchronous machines is generally limited by heating of the rotor windings. The hottest point of the windings is generally located relatively centrally in the radial direction, directly against the displacement body.

[0005] Cooling of the rotor windings is necessary due to the large rotor losses caused by the current in the rotor coils. As with other electric machines, heat dissipation from the rotor can be improved by rotor shaft cooling. Such rotor shaft cooling is known, for example, from U.S. Pat. No. 7,489,057, in which a cooling fluid flows axially through the rotor shaft. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent No. 7,489,057 Summary of the Invention [Problem to be solved by the invention]

[0007] A further development of rotor cooling compared to the embodiments described in the aforementioned U.S. patents is the spraying of oil onto the rotor winding head from the cooling circuit of the stator of a transmission or electronic machine. Compared to rotor shaft cooling, this concept dissipates heat at the source of loss. However, it has the disadvantage that only the outer ends of the rotor winding head are cooled, not the center of the rotor.

[0008] Also, to dissipate heat in the rotor center, the displacement bodies can be configured so that grooves for cooling the windings are integrated into each displacement body, resulting in a groove channel in each groove. To provide the necessary cavity in the displacement body, the rotor windings must be sealed with a plastic material, which also forms the cooling channels and the structure of the displacement body.

[0009] However, providing cooling channels through which a cooling medium flows within the rotor groove is only a prerequisite for dissipating waste heat generated during operation. To efficiently channel this waste heat from the windings into the cooling medium, low thermal resistance between the windings and the cooling channels is necessary. If the cooling channels are provided within a plastic displacement body, the low thermal conductivity of plastic hinders heat dissipation, resulting in wasted cooling capacity.

[0010] It can be seen from the above that the object of the present invention is to provide means for cooling the rotor windings as efficiently as possible without requiring additional installation space. [Means for solving the problem]

[0011] This problem is solved by the invention of the independent claims. Further preferred embodiments can be found in the dependent claims.

[0012] The present invention is based on the basic idea of ​​designing the displacement body body to have better heat conduction. For this purpose, according to the present invention, the displacement body can be designed as a stack of sheets insulated from each other. In this way, eddy current losses in the displacement body acting or being used as a heat sink can be avoided. The individual sheets can be made of aluminum, for example. When sheets coated with an insulating material are arranged adjacent to each other, the stack of sheets (layers) functionally corresponds to an alternating arrangement of conductive and non-conductive layers. The stacking direction of the sheets is parallel to the rotation axis of the rotor. In other words, the displacement body has a structure stacked in the depth direction.

[0013] In this type of displacement body, the displacement body through which the coolant flows is made of a metal material with good thermal conductivity instead of a plastic material with poor thermal conductivity. This improves the heat transfer from the rotor winding to the coolant, allowing for more efficient heat dissipation. To prevent stray losses in the metal displacement body, the displacement body configured as a metal heat sink can contain a paramagnetic metal, such as aluminum.

[0014] In various embodiments, a displacement body for a rotor is provided, the displacement body being configured to be inserted into a groove between every two rotor teeth, also commonly referred to as a rotor groove, and the displacement body can have a depth corresponding to the axial extension of the rotor groove.

[0015] In this case, the displacement body has a main portion and a head portion adjacent to the main portion perpendicular to the direction of extension of the displacement body, the head portion having a region extending outside the displacement body. The main portion may have a rectangular shape, and the head portion may have a trapezoidal shape adjacent to it. The displacement body further has at least one cooling channel extending in the depth direction through the displacement body. The depth direction corresponds to the axial direction of the rotor when the displacement body is inserted therein. The displacement body is configured as a layer stack (sheet or layer stack), and this layer stack includes at least two adjacent layers in the depth direction. Preferably, the layer stack can have several tens of layers. In particular, the first layer can include a conductive layer and the second layer can include a non-conductive layer, with the first and second layers forming an alternating layer arrangement. In this case, two adjacent insulating layers can be arranged as coatings on the conductive layer. In principle, all layers can have the same shape, i.e., they can be adjacent to each other without protruding laterally.

[0016] According to a further embodiment of the displacement body, the stack of layers can constitute a series of metal layers insulated from one another, in which, in the assembled state, the insulating protective layers of the sheets correspond to the insulating layers arranged between them.

[0017] According to a further embodiment of the displacement body, the individual sheets can consist of a metallic material, preferably a paramagnetic metal, for example aluminium, which is also a relatively light metal.

[0018] According to a further embodiment, the displacement body may further include at least one rib extending laterally outward from a main portion of the displacement body. When the displacement body is inserted into the rotor groove, the rib extends perpendicular to the axial direction of the rotor groove and therefore into the conductors of the winding. Each rib may be rod-shaped in cross section.

[0019] According to a further embodiment of the displacement body, an equal number of ribs may be arranged on each of two opposing side surfaces of the displacement body. Preferably, the displacement body may have a mirror-symmetric shape with an equal number of ribs on each of two corresponding side surfaces of the displacement body's main part.

[0020] According to a further embodiment of the displacement body, the length of the ribs may decrease from the inner end of the main part to the outer end of the main part. [Effects of the Invention]

[0021] The present invention also provides a rotor for an electric motor, the rotor having a laminated core on which rotor teeth are formed, and rotor windings disposed in grooves formed between the rotor teeth and wound around the rotor teeth, wherein at least some of the grooves are fitted with respective displacement bodies as described herein in the axial direction of the rotor. For example, such displacement bodies may be present in each rotor groove.

[0022] The use of the displacement body according to the invention in the stator of an electric machine can increase its continuous power output due to a higher thermal conductivity between the windings and the cooling channels. Furthermore, the layered structure of the heat sink can avoid degradation of the electromagnetic properties of the electric machine, so that the electric machine can still operate with high efficiency.

[0023] Further, according to the present invention, there is provided an electric motor having a stator and a rotor attached to the stator, the rotor being configured using at least one displacement body as described in the preceding paragraph and as described in this specification.

[0024] It is understood that the features mentioned above and those to be described below may not only be used in the combinations specified, but may also be used in other combinations or alone without departing from the scope of the present invention.

[0025] Further advantages and features of the invention can be obtained from the description and accompanying drawings. [Brief explanation of the drawings]

[0026] [Figure 1] 1 shows the rotor structure of a separately excited synchronous machine with groove channel cooling in a displacement body according to the prior art; [Figure 2] 1 shows the structure of a displacement body according to the invention having an axially layered structure. [Figure 3A] 10 shows a further embodiment of a displacement body inserted into a rotor groove; [Figure 3B] 10 shows a further embodiment of a displacement body inserted into a rotor groove; DETAILED DESCRIPTION OF THE INVENTION

[0027] 1 shows an exemplary structure of a rotor 1 of an individually excited synchronous machine with groove channel cooling in a displacement body 20. The rotor 1 comprises a rotor lamination (rotor lamination core) 2 in which rotor teeth are formed, spaced apart from one another by rotor grooves 3. In each rotor groove 3, a conductor 4 is arranged, which together form a rotor winding. In each rotor groove 3, a displacement body 20 having a wedge-shaped radial outer region is arranged, which prevents the conductor 4 from slipping under the effect of centrifugal force and thereby fixes the rotor winding 4 in the rotor groove 3. The rotor 1 is supported on a rotor shaft 5.

[0028] FIG. 2 shows an exemplary structure of a displacement body 20 according to the present invention, which has an axially stacked structure. The displacement body 20 according to the present invention is thus embodied as a sheet stack structure and can be divided into a main part 21 and a head part 22 directly connected thereto. Each sheet 23 of the sheet stack structure can be integrally formed and have a main part 21 and a head part 22. Each sheet 23 is surrounded by an insulating layer 24, which exists between the sheets 23, particularly in the axial direction (depth direction of the displacement body 20), and thereby functions as a separate layer. The stacking direction of the sheets 23 is parallel to the rotation axis of the rotor 1 shown in FIG. 1. To effectively dissipate heat loss, two cooling channels 25 are provided, each extending depthwise through the displacement body 20.

[0029] 3A and 3B show a further embodiment of a displacement body 20 inserted into a rotor groove 3 in a cross-section in the plane of the rotor seat. The displacement body 20 shown in FIG. 3A corresponds to the displacement body 20 shown in the cross-section of FIG. 2. The displacement body 20 shown in FIG. 3B has ribs 26 protruding laterally outward from its main part. Each rib 26 located on one side of the main part has a corresponding part on the opposite side of the main part. Furthermore, it can be seen that the length of the ribs 26 decreases as they are positioned closer to the outer or lower end of the main part of the displacement body body 20. This is thought to be due in particular to the shape of the rotor groove 3. [Explanation of symbols]

[0030] 1: rotor, 2: rotor laminated core, 3: rotor groove, 4: conductor, rotor winding, 5: rotor shaft, 20: displacement body, 21: main part, 22: head part, 23: sheet layer; 24: insulating layer; 25: cooling channel; 26: rib

Claims

1. A displacement body (20) for a rotor (1), comprising: The displacement body (20) is configured to be inserted into a groove between each of two rotor teeth; The displacement body (20) has a main portion (21) disposed in the groove in the radial direction of the rotor and a head portion (22) adjacent to the main portion, and the head portion (22) has a portion of the displacement body (20) that extends outward in the circumferential direction of the rotor, At least one cooling passage (25) is provided, which passes through the main portion of the displacement body (20) and extends in the direction of the rotation axis of the rotor; The displacement body (20) is configured as a layer stack having rows (23, 24) of metal layers insulated from each other in the rotation axis direction of the rotor, The displacement body (20) further has at least one rib (26) extending outward in the circumferential direction from a position where the cooling flow passage is provided in the main portion (21) of the displacement body (20) and extending into a conductor of a rotor winding disposed in the groove.

2. The displacement body (20) of claim 1, wherein the metal layer comprises a paramagnetic metal.

3. The displacement body (20) according to claim 1, wherein the same number of ribs (26) are arranged on each of two opposing sides of the displacement body (20).

4. 2. The displacement body (20) according to claim 1, wherein a plurality of the ribs are respectively arranged on both sides of the displacement body, and the plurality of ribs (26) include a first rib provided at the radially inner end of the main portion (21) and having a first lateral length, and a second rib provided at the radially outer end of the main portion (21) and having a second lateral length longer than the first lateral length.

5. A rotor (1) for an electric motor, comprising: The rotor (1) has a laminated core (2) in which rotor teeth are formed, A rotor winding is disposed in the grooves (3) formed between the rotor teeth, A rotor (1), wherein the displacement body (20) according to any one of claims 1 to 4 is inserted in the axial direction of the rotor (1) in at least a plurality of the grooves (3).

6. a stator; 6. An electric motor comprising: a rotor (1) mounted in the stator according to claim 5.

Images