ROTOR OF AN ELECTRICAL MACHINE

Description

State of the art

[0001] The invention is based on a rotor of an electrical machine according to the preamble of the independent main claim 1.

[0002] A rotor of an electrical machine is already known from US 5,889,342 B, having a rotor body rotatable about a rotor axis, which consists of at least one rotor sub-body designed as a rotor laminated core, and which has a plurality of cooling channels, each of which has a cooling channel opening at its end, wherein one cooling channel opening of one of the cooling channels is arranged radially further outward than the other cooling channel opening of the same cooling channel, such that a flow, in particular an air flow, is established in the cooling channel upon rotation of the rotor due to centrifugal forces. A cover element is provided on at least one of the two end faces of the rotor body, which cover a radially innermost partial cross-section of one of the cooling channel openings. The driving force for generating the air flow is generated by a radial offset between a channel of a hollow shaft of the rotor and one of the cooling channel openings of the rotor.

[0003] JPH02219447 A is considered to be the closest prior art and discloses the features of the preamble of independent main claim 1.

[0004] The object of the invention is to provide a rotor of an electrical machine, the rotation of which enables more efficient cooling of the rotor due to improved air flows in the rotor body.

[0005] The object of the invention is achieved by a rotor of an electrical machine according to the features of the independent main claim 1. Advantages of the invention

[0006] The rotor of the electric machine according to the invention with the characterizing features of independent main claim 1 has the advantage that no hollow shaft is required to generate the air flow in the rotor. The driving force for generating the air flow is generated solely in the respective cooling channel, which runs essentially in the axial direction, of the at least one rotor part body of the rotor. This is achieved according to the invention in that the first cover element covers the radially innermost partial cross-section of the respective cooling channel opening with an edge section that is radially outer with respect to the rotor axis and leaves a radially outermost partial cross-section of the same cooling channel opening uncovered as a cooling channel outlet. Furthermore, according to the invention, the other cooling channel opening of the same cooling channel is in each case a cooling channel inlet, wherein an inflow that is axial with respect to the rotor axis is provided upstream of the cooling channel inlets.In addition, according to the invention, the geometric center of gravity of the cooling channel outlet of one of the cooling channels is offset from the geometric center of gravity of the cooling channel inlet of the same cooling channel in the radial direction with respect to the rotor axis.

[0007] By means of the measures listed in the subclaims, advantageous further developments and improvements of the rotor specified in the independent main claim 1 are described in the dependent claims.

[0008] According to the invention, a second cover element is arranged on the other end face of the rotor body, and one of the cooling channel inlets is covered by one of the two cover elements at a radially outermost partial cross-section, and the associated cooling channel outlet of the same cooling channel is covered by the other cover element at a radially innermost partial cross-section, such that a radial offset is created between the uncovered or open cross-sections of the two cooling channel openings of one of the cooling channels. In this way, an air flow is generated in the rotor body upon rotation of the rotor.

[0009] It is very advantageous if the radial offset of the two cooling channel openings of one of the cooling channels is created exclusively by the two cover elements. In this way, the design of the rotor body remains unchanged, for example, with regard to the axial length, and the air flow is adjusted by the geometry or design of the cover elements.

[0010] It is also advantageous if the cooling channel inlet and outlet of each cooling channel in a first group of cooling channels are swapped end faces with the respective cooling channel inlet and outlet of a second group of cooling channels such that the cooling channels in the first group and the cooling channels in the second group are traversed in the opposite direction when the rotor rotates. In other words, the cooling channel inlet of the first group of cooling channels is located on one end face of the rotor and the cooling channel inlet of the second group of cooling channels is located on the other end face of the rotor. The same applies to the cooling channel outlets of the first and second groups of cooling channels. In this way, the air flows through the rotor body do not create a pressure difference between the cavities adjacent to the end face of the rotor.

[0011] According to advantageous embodiments, one or more sequences of at least one cooling channel of the first group of cooling channels and of at least one cooling channel of the second group of cooling channels can be provided along the circumference of the rotor.

[0012] Furthermore, it is advantageous if the cooling channel openings arranged on one of the two end faces of the rotor are each covered, in particular alternately in the circumferential direction, either at the radially outermost or at the radially innermost partial cross-section, and if the two cover elements are offset from one another in the circumferential direction, in particular by an angle corresponding to the angular distance between two adjacent cooling channels. In this way, two groups of cooling channels are formed in the rotor, through which flow occurs in opposite directions when the rotor rotates.

[0013] According to an advantageous embodiment, the two cover elements each have regions with different radial extensions. The first regions of the two cover elements each cover the radially innermost partial cross-sections of the cooling channel outlets. The second regions of the two cover elements, in contrast, each cover the radially outermost partial cross-sections of the cooling channel inlets and have through-openings opening into the respective cooling channel radially within the covered outermost partial cross-sections. Furthermore, the first regions of the two cover elements each have a smaller radial extension than the second regions. For example, the first region 15 forms an indentation, and the second region 16 forms a bulge.

[0014] It is also advantageous if the cover element is a disk, in particular a balancing disk or a sheet metal lamination of the at least one rotor sub-body. In this way, the function of generating air flow is integrated into an existing element of the rotor, allowing the axial length of the rotor to be reduced. drawing

[0015] 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 sectional view of a rotor according to the invention of an electrical machine along a line II in Fig.2 , Fig.2 a side view of the rotor according to the invention according to Fig.1 , Fig.3 a side view of the rotor according to the invention according to Fig.1 without a cover element according to the invention, Fig.4 a three-dimensional view of the rotor according to the invention of an electrical machine and Fig.5 an electrical machine with the rotor according to the invention according to Fig.1 bis Fig.4 . Description of the embodiment

[0016] Fig.1 shows a sectional view of a rotor according to the invention of an electrical machine along a line II in Fig.2 .

[0017] The rotor 1 of an electric machine has a rotor body 3 which is rotatable about a rotor axis 2 and which comprises at least one rotor sub-body 4, for example a rotor laminated core 4, and each has a plurality of cooling channels 5 distributed over the circumference of the rotor 1. A cooling channel 5 is understood to be a channel of the rotor body 3 through which air can flow. The cooling channels 5 each run from one end face of the rotor 1 with a substantially axial longitudinal extension to the other end face of the rotor 1. According to the exemplary embodiment, the rotor 1 has a plurality of rotor sub-bodies 4 which are rotated relative to one another in the circumferential direction with respect to the rotor axis 2 in a known manner and have corresponding cooling channel sections 5.1 to form the cooling channels 5. The cooling channels 5 each have a cooling channel opening 8 at their ends, wherein one cooling channel opening 8.1, one of the cooling channels 5 is arranged radially further outward than the other cooling channel opening 8.2 of the same cooling channel 5, such that a flow, in particular an air flow, is established in the cooling channel 5 upon rotation of the rotor 1 due to the centrifugal forces. In addition to the rotor body 3, the rotor 1 has a rotatable rotor shaft 6, which is connected to the rotor body 3 in a rotationally fixed manner.

[0018] On one of the two end faces of the rotor body 3, a first cover element 10 is provided, which covers a radially innermost partial cross-section of at least one of the cooling channel openings 8 of at least one of the cooling channels 5 with respect to the rotor axis 2.

[0019] According to the invention, the first cover element 10 covers the radially innermost partial cross-section of the respective cooling channel opening 8 with a radially outer edge section 11 with respect to the rotor axis 2 and leaves a radially outermost partial cross-section of the same cooling channel opening 8 uncovered as a cooling channel outlet 8.1. The other cooling channel opening 8.2 of the same cooling channel 5 is in each case a cooling channel inlet 8.2. Upstream of the cooling channel inlets 8.2, an axial inflow is provided with respect to the rotor axis 2. According to the invention, the geometric center of gravity S1 of the cooling channel outlet 8.1 is offset in the radial direction with respect to the rotor axis 2 relative to the geometric center of gravity S2 of the cooling channel inlet 8.2 of the same cooling channel 5. This can apply, for example, to all cooling channels 5 of the rotor 1.

[0020] A second cover element 12 is arranged on the other end face of the rotor body 3, which, for example, is designed identically to the first cover element 10. The two cover elements 10, 12 rest flush against one of the axially outer rotor sub-bodies 4 on one of the two end faces of the rotor body 3 and can be made of metal or plastic. The two cover elements 10, 12 can be designed as a disc, for example, as a balancing disc or as a sheet metal lamination of one of the rotor sub-bodies 4.

[0021] The respective cooling channel inlet 8.2, for example each cooling channel inlet 8.2 of the cooling channels 5 of the rotor 1, is covered by one of the two cover elements 10, 12 at a radially innermost partial cross-section, and the associated cooling channel outlet 8.1 of the same cooling channel 5 is covered by the other cover element 10, 12 at a radially outermost partial cross-section in such a way that a radial offset V is generated with respect to the rotor axis 2 between the uncovered or open cross-sections of the two cooling channel openings 8.1, 8.2 of one of the cooling channels 5. The radial offset V of the two cooling channel openings 8 of one of the cooling channels 5 is generated exclusively by the two cover elements 10, 12.

[0022] The cooling channel inlet 8.2 and the cooling channel outlet 8.1 of each cooling channel 5 of a first group of cooling channels 5 are each swapped end faces with respect to the respective cooling channel inlet 8.2 and cooling channel outlet 8.1 of a second group of cooling channels 5 such that the cooling channels 5 of the first group and the cooling channels 5 of the second group are flowed through in the opposite direction when the rotor 1 rotates.

[0023] The cooling channels 5 of the first group of cooling channels 5 and the cooling channels 5 of the second group of cooling channels 5 can be distributed as desired over the circumference of the rotor 1. For example, one or more sequences of at least one cooling channel 5 of the first group of cooling channels 5 and of at least one cooling channel 5 of the second group of cooling channels 5 are provided along the circumference of the rotor 1. According to the exemplary embodiment, a sequence of a cooling channel 5 of the first group and a cooling channel 5 of the second group is arranged multiple times one behind the other in the circumferential direction. Alternatively, a plurality of cooling channels of the first group or even a plurality of cooling channels of the second group can be arranged adjacent to one another, so that a sequence of a plurality of cooling channels 5 of the first group and a plurality of cooling channels 5 of the second group is formed.Furthermore, only one sequence of cooling channels 5 of the first group and cooling channels 5 of the second group can be provided over the circumference of the rotor 1.

[0024] The two cover elements 10, 12 are offset from one another in the circumferential direction in order to achieve the radial offset of the two cooling channel openings 8 of one of the cooling channels 5 according to the invention, for example by an angle which corresponds to an angular distance between two adjacent cooling channels 5.

[0025] Fig.2 shows a side view of the rotor according to the invention according to Fig.1 .

[0026] In the rotor body 3, at least one permanent magnet 13 is also arranged per rotor pole, the receptacle of which in the rotor body 3 is covered on the front side, for example by a cover 14.

[0027] The cooling channel openings 8 arranged on one of the two end faces of the rotor 1 are each covered, for example alternately in the circumferential direction, either at the radially outermost or at the radially innermost partial cross-section.

[0028] The two cover elements 10, 12 each have regions with different radial extensions. First regions 15 of the two cover elements 10, 12 each cover the radially innermost partial cross-sections of the cooling channel outlets 8.1 with the radially outer edge section 11. Second regions 16 of the two cover elements 10, 12 each cover the radially outermost partial cross-sections of the cooling channel inlets 8.2 with the radially outer edge section 11 and have through-openings 17 opening into the respective cooling channel 5 radially within the covered outermost partial cross-sections. Furthermore, the first regions 15 of the two cover elements 10, 12 each have a smaller radial extension than the second regions 16. According to the exemplary embodiment, a sequence of a first region 15 and a second region 16 is arranged several times one behind the other in the circumferential direction. Thus, a first region 15 is arranged between each two second regions 16.The first region 15 forms, for example, an indentation and the second region 16 forms, for example, a bulge.

[0029] The number of through openings 17 in the cover element 10, 12 corresponds to half the number of cooling channel openings 8 on one of the two end faces of the rotor body 3.

[0030] Fig.3 shows a side view of the rotor according to the invention according to Fig.1 without the cover element according to the invention. The cross-section of the cooling channels 5 is arbitrary and, according to the exemplary embodiment, is diamond-shaped.

[0031] Fig.4 shows a three-dimensional view of the rotor of an electrical machine according to the invention.

[0032] Fig.5 shows an electrical machine with the rotor according to the invention according to Fig.1 bis Fig.4 The rotor 1 is surrounded by a stator 20. The stator 20 is arranged in a machine housing 21.

[0033] The two cooling channel openings 8 of the respective cooling channels 5 of the rotor 1 lead in the axial direction relative to the rotor axis 2 into a housing interior 22 of the electric machine, which is adjacent to the rotor 1 at the end face and is, for example, air-filled. The housing interior 22 comprises a volume formed radially within a winding head 23 of the stator 20.

Claims

1. Rotor of an electric machine, having a rotor body (3) which is rotatable about a rotor axis (2), comprises at least one rotor body element (4), in particular a rotor laminated core (4), and has in each case one or more cooling ducts (5) which each have a cooling duct opening (8.1, 8.2) at their ends, wherein the one cooling duct opening (8.1) of one of the cooling ducts (5) is in each case arranged radially farther outside than the other cooling duct opening (8.2) of the same cooling duct (5), in such a way that an air flow is established in the cooling duct (5) owing to the centrifugal forces when the rotor (1) rotates, wherein a first cover element (10) is provided on one of the two end sides of the rotor body (3) and covers a radially innermost partial cross section of at least one of the cooling duct openings (8.1) of at least one of the cooling ducts (5), characterized in that - the first cover element (10) covers the radially innermost partial cross section of the respective cooling duct opening (8.1) by way of a radially outer edge portion (11) with respect to the rotor axis (2) and in each case leaves a radially outermost partial cross section of the same cooling duct opening (8.1) uncovered as cooling duct outlet (8.1), in that - the other cooling duct opening (8.2) of the same cooling duct (5) is in each case a cooling duct inlet, and in that a respective axial inflow with respect to the rotor axis (2) is provided upstream of the cooling duct inlets (8.2), in that - the geometric centre (S1) of the cooling duct outlet (8.1) is offset in the radial direction with respect to the rotor axis (2) in each case in relation to the geometric centre (S2) of the cooling duct inlet (8.2) of the same cooling duct (5), in that - a second cover element (12) is arranged on the other end side of the rotor body (3), and one of the cooling duct inlets (8.2) is covered in each case by one of the two cover elements (10, 12) at a radially outermost partial cross section, and the assigned cooling duct outlet (8.1) of the same cooling duct (5) is covered in each case by the other cover element (10, 12) at a radially innermost partial cross section, in such a way that a respective radial offset (V) between the uncovered or open cross sections of the two cooling duct openings (8.1, 8.2) of one of the cooling ducts (5) is generated.

2. Rotor according to Claim 1, characterized in that the radial offset (V) of the two cooling duct openings (8.1, 8.2) of one of the cooling ducts (5) is generated exclusively by the two cover elements (10, 12).

3. Rotor according to either of the preceding claims, characterized in that the cooling duct inlet (8.2) and the cooling duct outlet (8.1) of each cooling duct (5) of a first group of cooling ducts (5) are in each case reversed in terms of end side in relation to the respective cooling duct inlet (8.2) and cooling duct outlet (8.1) of a second group of cooling ducts (5) in such a way that the cooling ducts (5) of the first group and the cooling ducts (5) of the second group are flowed through in opposite directions when the rotor (1) rotates.

4. Rotor according to Claim 3, characterized in that one or more sequences of at least one cooling duct (5) of the first group of cooling ducts (5) and of at least one cooling duct (5) of the second group of cooling ducts (5) is / are provided along the circumference of the rotor (1).

5. Rotor according to one of Claims 1 to 4, characterized in that the cooling duct openings (8.1, 8.2) arranged on one of the two end sides of the rotor (1) are in each case covered, in particular so as to alternate in the circumferential direction, either at the radially outermost or at the radially innermost partial cross section, and in that the two cover elements (10, 12) are offset relative to one another in the circumferential direction, in particular by an angle which corresponds to an angular spacing between two adjacent cooling ducts (5).

6. Rotor according to Claim 5, characterized in that the two cover elements (10, 12) each have regions (15, 16) of different radial extent, wherein first regions (15) of the two cover elements (10, 12) cover in each case the radially innermost partial cross sections of the cooling duct outlets (8.1), wherein second regions (16) of the two cover elements (10, 12) cover in each case the radially outermost partial cross sections of the cooling duct inlets (8.2) and have passage openings (17) which lead into the respective cooling duct (5) radially within the covered outermost partial cross sections, and wherein the first regions (15) of the two cover elements (10, 12) each have a smaller radial extent than the second regions (16).

7. Rotor according to one of the preceding claims, characterized in that the first and / or second cover element (10, 12) are / is a disc, in particular a balancing disc or a sheet-metal lamination of the at least one rotor body element (4).

8. Rotor according to one of the preceding claims, characterized in that the cooling ducts (5) of the rotor body (3) and / or the cooling duct portions (5.1) of each rotor body element (4) of the rotor body (3) run in the axial direction with respect to the rotor axis (2).

9. Electric machine having a stator (20) and a rotor (1) according to one of the preceding claims, wherein the two cooling duct openings (8.1, 8.2) of the respective cooling duct (5) of the rotor (1) lead in the axial direction into an in particular air-filled housing interior (22) of the electric machine, said housing interior adjoining the rotor (1) at the end side.