STATOR OF AN ELECTRIC MACHINE

Description

State of the art

[0001] The invention is based on a stator of an electrical machine according to the preamble of the main claim.

[0002] A stator of an electrical machine is already known from EP 1 364 440 B1, which has stator slots and conductor elements arranged in the stator slots, each having two conductor ends. A plurality of adjacent conductor ends of different conductor elements are each connected to one another by means of a welded connection provided on the end faces of the respective conductor ends, without additional material. The interconnected conductor ends each form a common quadrangular conductor cross-section having a height H and a width B, wherein the height H corresponds to the height h of an individual cross-section of the conductor ends and the width B of the common conductor cross-section results from the sum of the widths b of the individual cross-sections of the conductor ends. The welded connection is provided in each case between two unmelted edge sections of the outermost conductor ends, viewed in the direction of the width B.The weld cross-section in the direction of height H is comparatively small, which impacts the mechanical fatigue strength of the welded joint and can cause temperature peaks at the welded joint due to high current density during operation of the electrical machine. Further relevant prior art is disclosed in US 2014 / 048518 A1, US 2016 / 118869 A1, and DE 600 01 526 T2. Advantages of the invention

[0003] The stator of an electrical machine according to the invention with the characterizing features of the main claim has the advantage that the mechanical strength of the welded joint is increased and the temperature peaks at the welded joint are at least reduced by the extent of the welded joint in the direction of the height H being at least partially greater than the height H of the common conductor cross-section. The welded joint therefore protrudes in the direction of the height H relative to the edge sections of the outermost conductor ends. The bilateral protrusion or projection of the welded joint requires material that comes from the molten weld pool and causes the surface of the welded joint to sink in relation to the end faces of the edge sections. The sunken welded joint has the advantage that it does not raise the winding overhang in the axial direction of the stator, thus saving installation space.

[0004] The measures listed in the subclaims enable advantageous further developments and improvements of the stator specified in the main claim.

[0005] According to an advantageous embodiment, the welded joint is oval or circular when viewed from above at the end faces of the respective conductor ends. Furthermore, the welded joint has an oval cross-section when viewed in the direction of its longitudinal extension.

[0006] It is particularly advantageous if the ratio of the width B to the height H of the common conductor cross-section is greater than two, since this facilitates the sinking of the molten weld pool and thus prevents the winding head from raising in the axial direction.

[0007] It is also advantageous if the cross-section of the conductor ends each has a height h and a width b, with the ratio of the width b to the height h of the cross-section of the conductor ends being greater than or equal to one. This creates a favorable aspect ratio for two conductor ends to be connected, which facilitates the sinking of the molten weld pool. Using a ratio of the width b to the height h of the cross-section of the conductor ends greater than or equal to 1.4 allows the use of flat wires that place low demands on the enamel wire coating process.

[0008] It is very advantageous if the cross-section of the conductor ends is square or rectangular, in particular with rounded edges, since this enables a high electrical fill factor for the electrical machine. drawing

[0009] An embodiment of the invention is shown in simplified form in the drawing and explained in more detail in the following description. Fig.1 shows a three-dimensional view of a stator of an electrical machine to which the invention can be applied, Fig.2 a side view of a welded connection according to the invention between two conductor ends of two conductor elements and Fig.3 a plan view of the welded connection according to Fig.2 . Description of the embodiment

[0010] Fig.1 shows a three-dimensional view of a stator of an electrical machine to which the invention can be applied.

[0011] The stator 1 of the electrical machine has a stator laminated core 2 with stator slots 3. Conductor elements 4 of an electrical winding, each having two conductor ends 5, are provided in the stator slots 3. In order to form an electrical winding, for example a multi-phase winding, the conductor ends 5 of the plurality of conductor elements 4 must be firmly bonded to one another according to a so-called winding pattern. For this purpose, two or more adjacent conductor ends 5 of different conductor elements 4 are connected to one another by means of a welded joint or a weld seam 8. This welded joint 8 is provided on the end faces 6 of the respective conductor ends 5 and is produced by means of a laser and without the use of any additional material.After welding, the welded joints 8 can each be enclosed by an insulation (not shown) in order to prevent sparkovers between conductor ends 5 of different electrical phases.

[0012] Fig.2 shows a side view of a welded joint according to the invention between two conductor ends of two conductor elements. In the view according to Fig.2 are the opposite of the opinion Fig.1 Parts that remain the same or have the same function are identified by the same reference symbols.

[0013] The end faces 6 of the conductor ends 5 to be connected are provided flush with one another. The individual cross-sections of the conductor ends 5 each have a height h and a width b. The conductor ends 5 to be connected to one another each form a common square, in particular rectangular, conductor cross-section 9 which has a height H and a width B, wherein the height H corresponds to the height h of the individual cross-sections of the conductor ends 5 and the width B of the common conductor cross-section 9 results from the sum of the widths b of the individual cross-sections of the conductor ends 5. The common conductor cross-section 9 therefore refers to the cross-section resulting from the juxtaposition of the square, in particular rectangular, individual cross-sections of the conductor ends 5. The individual cross-sections have, for example, rounded edges. The ratio of the width B to the height H of the common conductor cross-section 9 is greater than two.The ratio of the width b to the height h of each individual cross-section of the conductor ends 5 is greater than or equal to one. The conductor ends 5 to be connected have a common circumference formed by two opposite wide circumferential sides U1 and two opposite narrow circumferential sides U2.

[0014] According to the example in Fig.2 Two conductor ends 5 are connected by means of the welded joint 8. The welded joint 8 is provided between two unmelted edge sections 10 of the outermost conductor ends 5, as viewed in the direction of width B. The welded joint 8 is thus designed such that, as viewed in the direction of width B, the edge sections 10 remain unmelted at the two opposite edges of the common conductor cross-section 9. Thus, the weld seam 8, with its longitudinal extension L1, does not extend across the entire width B of the common conductor cross-section 9.

[0015] According to the invention, the extension L2 of the welded joint 8 transversely, for example perpendicularly, to the longitudinal extension L1 in the direction of the height H is at least partially greater than the height H of the common conductor cross-section 9, and the surface of the welded joint 8 is consequently sunk in relative to the end faces 6 of the edge sections 10. The reference point for the sunk in of the welded joint can also be the entire end face 6 of the conductor ends 5 before welding.

[0016] Due to the inventive design, the welded joint 8 protrudes with its extension L2 on both wide circumferential sides U1 relative to the edge portions 10 of the outermost conductor ends 5. Furthermore, the welded joint 8 protrudes on both sides relative to the circumferential sides U1 in the area immediately below the welded joint 8.

[0017] The surface of the welded joint 8 has sunk by a certain depth T over the entire extension L1 of the welded joint 8, forming a recess 12. The material from the recess 12 has flowed into the two laterally projecting sections 8.1 of the welded joint 8. The welded joint 8 has an oval cross-section viewed in the direction of the longitudinal extension L1 of the welded joint 8.

[0018] The welded joint 8 is oval or circular in shape when viewed in the direction of the end faces of the respective conductor ends.

[0019] The welded joint 8 according to the invention is produced according to the following method steps: First, the conductor ends to be connected are stripped of insulation and arranged side by side. Subsequently, the material at the end faces 6 of the conductor ends 5 is locally melted by oscillating a laser beam back and forth, with the pivoting range of the laser being adjusted such that the forming weld pool is held between a non-melted edge section 10 of one of the two outermost conductor elements 4 and a non-melted edge section 10 of the other outermost conductor element 4. The welding parameters, in particular the laser power, a laser beam thickness, and a welding time, are adjusted such that the extension of the welded joint in the direction of the height H is, at least in some sections, greater than the height H of the common conductor cross-section 9.

[0020] The welded conductor ends 5, in particular the edge sections 10 of the conductor ends 5, can each be rounded at their edges in order to achieve a reduced field line concentration and thus a higher insulation or dielectric strength by avoiding burrs and points. An electrically insulating coating (not shown) can be applied to the rounded, welded conductor ends 5 after welding. By rounding the welded conductor ends 5, the insulation coating on the welded conductor ends 5 has a more uniform layer thickness than with non-rounded conductor ends 5. Without the rounding of the conductor ends 5, the insulation coating would have a smaller layer thickness at the edges, burrs or points of the conductor ends 5, so that the insulation or dielectric strength would be reduced there.The rounding of the conductor ends 5 can be produced before the welding of the conductor ends 5, for example by mechanical processing or during the welding process by melting the edges or after welding by mechanical processing.

[0021] Fig.3 shows a top view of the front side of the conductor ends with the welded connection according to Fig.2 . When viewed according to Fig.3 are the opposite of the opinion Fig.1 and Fig.2 Parts that remain the same or have the same function are identified by the same reference symbols.

Claims

1. Method for producing a weld connection (8) of a stator of an electric machine having stator slots (3) and conductor elements (4) that are arranged in the stator slots (3) and that each comprise two conductor ends (5), wherein multiple adjacent-lying conductor ends (5) of different conductor elements (4) are mutually connected without the use of an additional material by means of a weld connection (8) that is provided at the end faces (6) of the relevant conductor ends (5), wherein the mutually connected conductor ends (5) each form a common four-cornered conductor cross section (9) that has a height (H) and a width (B), wherein the height (H) corresponds to the height (h) of an individual cross section of the conductor ends (5) and the width (B) of the common conductor cross section (9) is formed from the sum of the widths (b) of the individual cross sections of the conductor ends (5), the method comprising the following steps: - arranging the conductor ends (5) adjacent to one another, - locally melting the material at the end faces (6) of the conductor ends (5) by means of moving a laser beam to and fro in a pendulum manner, wherein the pivot range of the laser is adjusted in such a manner that the weld pool that is formed is retained between a non-melted boundary section (10) of one of the two outermost conductor elements (4) and a non-melted boundary section (10) of the other outermost conductor element (4), characterized by the following steps: - stripping insulation from the conductor ends (5) that are to be connected, and - adjusting the weld parameters, in particular the power of the laser, a beam thickness of the laser and a weld time in such a manner that the extension (L2) of the weld connection (8) in the direction of the height (H) is greater at least in sections than the height (H) of the common conductor cross section (9) and the surface of the weld connection (8) with regard to the end faces (6) of the boundary sections (10) is sunk in as a result.

2. Method according to Claim 1, additionally comprising the step of applying an insulation coating to the mutually welded conductor ends.

3. Method according to either one of the preceding claims, characterized in that the weld connection (8), when viewed in the direction of the height (H), protrudes beyond the boundary sections (10) of the outermost conductor ends (5), in particular on both sides.

4. Method according to any one of the preceding claims, characterized in that the surface of the weld connection (8) is sunken in over the entire longitudinal extension (L1) of the weld connection (8).

5. Method according to any one of the preceding claims, characterized in that the weld connection (8) in the case of a plan view of the end faces (6) of the relevant conductor ends (5) is configured in an oval shape.

6. Method according to any one of the preceding claims, characterized in that, when viewed in the direction of the longitudinal extension (L1) of the weld connection (8), the weld connection (8) has an oval cross section.

7. Method according to any one of the preceding claims, characterized in that the ratio of the width (B) with respect to the height (H) of the common conductor cross section (9) is greater than two.

8. Method according to any one of the preceding claims, characterized in that the individual cross section of the conductor ends (5) has in each case a height (h) and a width (b), wherein the ratio of the width (b) with respect to the height (h) of the individual cross section of the conductor ends (5) is in each case greater than or equal to one.

9. Method according to any one of the preceding claims, characterized in that the individual cross section of the conductor ends (5) is configured in each case in a square-shaped or rectangular manner, in particular with rounded edges.

10. Method according to any one of the preceding claims, characterized in that the mutually connected conductor ends (5), in particular the boundary sections (10), are configured in a rounded manner.