Electric machine

Abstract

The present invention relates to an electrical machine (1) with a stator (2) and a rotor shaft (4) mounted on the stator so as to be rotatably adjustable about a rotational axis (3), with a primary coil (5) arranged on the stator (2) and a secondary coil (6) arranged on the rotor shaft (4), which is inductively coupled to the primary coil (5) during operation of the electrical machine (1) so that electrical energy is transferred from the primary coil (5) to the secondary coil (6). It is essential for the invention that the electronic rectifier components (9) of a rectifier device (7) are arranged within a receptacle (15) of a rectifier housing (8) of the rectifier device (7) and are indirectly cooled by cooling channels (17) of the rectifier housing (8).

Description

[0001] The invention relates to an electrical machine according to the preamble of claim 1.

[0002] Such electrical machines, especially so-called separately excited synchronous machines, require a direct current in their rotor to generate the magnetic rotor field. This process is referred to as "rotor excitation." In conventional separately excited synchronous machines, the electrical rotor voltage is transferred to the rotating rotor as a direct current using so-called carbon brush slip ring contacts. A disadvantage of this is that the carbon brushes wear down due to wear, especially at high speeds, and can generate unwanted electrically conductive carbon dust.

[0003] As an alternative to such a transmission of direct current using slip rings, it is known to realize the electrical voltage transmission to the rotating rotor inductively, i.e., contactlessly. Such a configuration, as part of a separately excited synchronous machine, is also referred to as a "rotary transformer" or inductive transformer.

[0004] The operating principle of this inductive energy transfer is based on an electrical transformer, with the primary coil of the transformer located on the stator of the electrical machine and the secondary coil on the rotating rotor. Since inductive energy transfer always initially generates an alternating voltage in the secondary coil, it is necessary to electrically rectify the generated alternating voltage using a suitable rectifier, i.e., convert it into a direct voltage.

[0005] During this conversion specifically, as well as during the operation of the electrical machine in general, various energy losses occur in the form of heat, which causes the rotor of the electrical machine, in particular, to heat up. A maximum permissible operating temperature is determined by the insulation materials used (e.g., insulating paper, enameled copper wire) and, in particular, by the electronic rectifier components of the rectifier device. This temperature is generally in the range of approximately 140°C to 180°C. Accordingly, efficient cooling of the rotor and the electronic rectifier components is crucial for the electrical machine to deliver the required peak and continuous power.

[0006] An electrical machine of the type mentioned above is known from DE 28 19 824 C2, in which, for cooling electronic rectifier components accommodated in a housing of a rectifier device, a coolant flows into the housing via an axial central opening, is guided past the rectifier components, and then flows out through slots arranged radially on the outside of a housing cover. A particular disadvantage is that the housing of the rectifier device has a relatively complex construction due to the cooling implemented, with the precise positioning of the housing cover on a bottom wall of the housing supporting the electronic rectifier components, in particular, posing a risk of rotor imbalance at high speeds. Furthermore, individual wires for electrically connecting the electronic rectifier components to terminals of the housing have proven to be mechanically vulnerable and costly.

[0007] Further electrical machines are discussed in the documents DE 28 19 824 C2, DE 10 2015 014 535 A1 and US 2006 / 0176720 A1.

[0008] The object of the invention is therefore to provide an improved or at least a different embodiment for an electrical machine. In particular, improved cooling of the electronic rectifier components is to be achieved.

[0009] In the present invention, this object is achieved in particular by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims and the description.

[0010] Accordingly, an electrical machine is proposed, in particular a separately excited synchronous electrical machine, comprising a stator and a rotor mounted thereon so as to be rotatably adjustable about a rotational axis, with a rotor shaft. Furthermore, a primary coil is arranged on the stator, and a secondary coil is arranged on the rotor shaft. During operation of the electrical machine, the secondary coil is inductively coupled to the primary coil, so that electrical energy is transferred from the primary coil to the secondary coil without contact.The electrical machine further comprises a rectifier device for converting an alternating electrical voltage generated in the secondary coil during inductive energy transfer into a direct electrical voltage, wherein the rectifier device comprises a rectifier housing arranged on the rotor shaft and electronic rectifier components for converting the alternating electrical voltage into a direct electrical voltage. The rectifier housing has an annular housing base oriented transversely, and in particular perpendicularly, to the axis of rotation and concentric with respect to the axis of rotation, with a through-opening for stationary reception of the rotor shaft, and an outer peripheral wall projecting away from the housing base, in particular parallel with respect to the axis of rotation and / or perpendicular to the housing base, concentric with respect to the axis of rotation and with an inner circumference facing the axis of rotation.The housing base and the outer peripheral wall are preferably designed as an integral part, i.e., made from a single casting, so to speak. Furthermore, it is provided that the rectifier housing has a receptacle which is arranged transversely with respect to the axis of rotation, and in particular perpendicular to the axis of rotation, between the inner circumference of the outer peripheral wall and the axis of rotation. The receptacle could therefore also be referred to as an inner receptacle. The receptacle can be designed to be open on one side, for example in the direction of the axis of rotation, and can have a receptacle opening so that, for example, the electronic rectifier components can be inserted into the receptacle during assembly. The receptacle opening can be closed by a cover of the rectifier housing or it can be open.It is essential for the invention that the said electronic rectifier components are evenly distributed in a circumferential direction around the axis of rotation, are arranged within the receptacle of the rectifier housing on the inner circumference of the outer circumferential wall and that the rectifier housing has cooling channels through which coolant can flow to realize indirect cooling of the electronic rectifier components.

[0011] This allows for efficient cooling of the electronic rectifier components arranged on the inner circumference, particularly at higher rotor shaft speeds. This has the advantage that the proposed electric machine can either provide higher continuous power at a constant operating temperature or operate at a lower operating temperature while maintaining constant continuous power, thus reducing thermal stress and increasing the expected service life.Furthermore, during operation of the electric machine, the electronic rectifier components can be supported on the inner circumference of the rectifier housing against the centrifugal forces acting on them, which advantageously reduces the risk of damage and ensures optimal thermal connection of the electronic rectifier components to the inner circumference due to the increased contact pressure caused by the centrifugal forces. Arranging the electronic rectifier components on the inner circumference also has the advantage that the thermal path between an electronic rectifier component and the coolant flowing through a cooling channel is relatively short, allowing heat to be optimally transferred from the electronic rectifier components to the coolant. This improves the efficiency and expected overall service life of the electric machine.

[0012] An electrically non-conductive cooling oil can be used as a coolant.

[0013] Furthermore, it can be provided that the rectifier device, in particular the rectifier housing, is integrated into a balancing plate and / or a winding support of the rotor of the electrical machine.

[0014] It is also conceivable for the rotor shaft to be pushed through the through-opening of the rectifier housing, and for the rectifier housing to then be pressed onto the rotor shaft, so that the rotor shaft and the rectifier housing are practically permanently fixed to one another. In this context, it is also conceivable for the through-opening of the rectifier housing to have a cylindrical bearing projection arranged on the housing base and projecting away from the housing base, particularly parallel to the axis of rotation.

[0015] It is expedient for said cooling channels to run, in particular exclusively, through the outer peripheral wall. The cooling channels can be integrated into the outer peripheral wall relatively easily and inexpensively. In addition, the arrangement of the cooling channels in the outer peripheral wall offers the advantage that heat absorbed by the coolant, in particular by the electronic rectifier components, during operation of the electrical machine as it flows through the cooling channels can be transferred and carried away via an outer peripheral surface of the outer peripheral wall radially opposite the inner peripheral surface of the outer peripheral wall to, for example, a coolant that is applied to this outer peripheral surface, in particular by spraying. This can significantly improve the removal of heat from the electronic rectifier components and thus provide efficient cooling.

[0016] Furthermore, different designs of the cooling channels are conceivable. In particular, it can be provided that the cooling channels are designed as longitudinal channels that pass through the outer peripheral wall parallel to the axis of rotation. A "longitudinal channel" within the meaning of the invention is a straight, curvature-free channel through which flow runs parallel to the axis of rotation. The length of the longitudinal channels expediently corresponds to an axial width of the rectifier housing, which is to be measured in the direction of the axis of rotation between an end ring surface of the housing base facing away from the receptacle and a counter end ring surface of the outer peripheral wall facing away from the end ring surface of the housing base. In this case, the said end ring surface and the counter end ring surface expediently lie opposite one another parallel to the axis of rotation.This allows the coolant to flow through the cooling channels parallel to the rotational axis during operation of the electric machine, enabling efficient cooling, especially since a comparatively high mass flow of coolant can be transported through the rectifier housing. Furthermore, the longitudinal channels can be provided cost-effectively, for example, by machining the outer peripheral wall, in particular by drilling, or by casting the rectifier housing. The longitudinal channels are then created by cores inserted and encapsulated during the casting or injection molding of the rectifier housing.

[0017] Furthermore, it can be provided that the cooling channels are designed as helical channels, each of which penetrates the outer circumferential wall in a cylindrical spiral shape and coaxial with the axis of rotation. The helical channels can run twisted into one another through the outer circumferential wall. In other words, the helical channels run in the direction of the axis of rotation along a spiral or screw line that are intertwined with one another. The helical channels and in particular their twisting ensure that heat that is absorbed by the coolant during operation of the electrical machine as it flows through the cooling channels, in particular by the electronic rectifier components, is evenly distributed across the entire outer circumferential wall, so that a comparatively homogeneous temperature distribution that is free of local heat hotspots is achieved in the rectifier housing.This also significantly improves heat dissipation from the electronic rectifier components, thus providing efficient cooling. Such helical channels can be produced cost-effectively, particularly through casting. For example, they can be created during the manufacture of the rectifier housing by casting or injection molding using cores inserted and encapsulated in the rectifier housing.

[0018] It is understood that at least one cooling channel can be realized as a longitudinal channel and / or at least one cooling channel as a helical channel.

[0019] Furthermore, it may be expedient for the housing base to have an end ring surface facing away from the receptacle, oriented transversely and in particular perpendicularly to the axis of rotation, and for the outer peripheral wall to have a counter end ring surface facing away from the end ring surface of the housing base, in particular opposite the end ring surface of the housing base parallel to the axis of rotation, and oriented transversely and in particular perpendicularly to the axis of rotation. In this case, the cooling channels open out at least partially at an outer edge of the end ring surface of the housing base, forming inlet openings, and furthermore at the counter end ring surface of the outer peripheral wall, forming outlet openings. As a result, during operation of the electric machine, the coolant can be applied, for example, to the end ring surface of the housing base, for example by spraying it on, and then flow via the end ring surface into the inlet openings of the cooling channels.The coolant can then flow through the cooling channels, taking heat with it, particularly from the electronic rectifier components, and then flow out of the cooling channels downstream through the opposite outlet openings.

[0020] Furthermore, said end ring surface of the housing base can be designed to be completely flat or at least partially flat. Furthermore, it may be expedient for the end ring surface of the housing base to be curved at its outer edge toward the receptacle and otherwise flat. The end ring surface of the housing base can thus have an overall dome-shaped configuration.

[0021] Conveniently, the inner circumference of the outer circumferential wall can run parallel to the axis of rotation.

[0022] It is also expedient if the coolant is applied, in particular sprayed, to the end ring surface of the housing base during operation of the electric machine and, since the rotor shaft rotates about the axis of rotation during operation of the electric machine, is then accelerated radially outwards by the acting centrifugal forces. Since the inlet openings of the cooling channels are arranged on an outer edge of the end ring surface of the housing base, the coolant can flow relatively easily, so to speak automatically, via the end ring surface of the housing base into the inlet openings of the cooling channels. The end ring surface of the housing base thus serves, so to speak, on the one hand as a collecting surface for the coolant and, on the other hand, as a guide surface along which the coolant is accelerated radially outwards and guided to the inlet openings.

[0023] In order to apply the coolant to the end ring surface of the housing base by spraying it, as mentioned, the electric machine can be provided with one or more spray nozzles for spraying coolant. The spray nozzles can expediently apply coolant not only to the end ring surface of the housing base, but also to an outer circumference of the outer circumferential wall, which is radially opposite the inner circumference of the outer circumferential wall and faces away from the axis of rotation. Furthermore, it is conceivable for the rotor shaft to be designed as a hollow rotor shaft through which the coolant can flow, so that the coolant can be sprayed from a coolant source onto the end ring surface of the housing base and / or the said outer circumference of the outer circumferential wall via one or more radial and / or axial outlet bores in the rotor shaft.Alternatively, it can be provided that coolant conveying geometries for conveying coolant are arranged on the rotor shaft, which convey the coolant from a coolant source onto the end ring surface of the housing base and / or the said outer circumference of the outer circumferential wall.

[0024] It is expedient to arrange the cooling channels within the outer circumferential wall so that they are evenly distributed relative to one another in the circumferential direction. This can mean, in particular, that the cooling channels are spaced identically from one another in the circumferential direction. This allows for homogeneous heat dissipation from the rectifier housing and, at the same time, smooth, unbalance-free running of the rotor of the electric machine.

[0025] Furthermore, it can be provided that each electronic rectifier component is assigned exactly one or two cooling channels, in particular one or two said longitudinal or helical channels, in such a way that the coolant flowing through two such cooling channels assigned to an electronic rectifier component has a greater heat exchange with this electronic rectifier component than with a neighboring, further electronic rectifier component. In this case, the two cooling channels assigned to an electronic rectifier component can be spaced apart from one another in the circumferential direction, wherein this spacing is smaller than a further spacing from a neighboring, further cooling channel assigned to a further electronic rectifier component in the circumferential direction. As a result, heat can be transferred particularly efficiently from the electronic rectifier components to the coolant and then carried away.

[0026] It is expedient for the cooling channels to taper in the direction of the rotation axis. This can be provided in particular for the said longitudinal channels or also for the said helical channels. In this case, the cooling channels can taper from the said counter-end ring surface of the outer peripheral wall in the direction of the rotation axis to the end ring surface of the housing base. This means that the cooling channels converge from the counter-end ring surface towards the end ring surface of the housing base. As a result, the said inlet openings of the cooling channels can each have an inlet opening cross-sectional area that is smaller in area than the outlet opening cross-sectional areas of the opposite outlet openings.This promotes the outflow of coolant through the outlet openings of the cooling channels, since as the cross-sectional area of ​​a cooling channel increases, the pressure loss within the cooling channel through which it flows is reduced. This creates a preferred flow direction of the coolant in the cooling channels from the inlet openings to the outlet openings. Furthermore, such a geometry—a cross-sectional area that increases in the channel direction and especially in the axial direction—can be used as a draft angle in an injection molding or casting process and enables or simplifies production by casting, e.g., die casting, using reusable casting cores.

[0027] It is further expediently provided that the housing base has an end ring surface facing away from the receptacle, oriented transversely and in particular perpendicularly to the axis of rotation, the housing base furthermore having a rim which completely surrounds the end ring surface of the housing base radially outward in the circumferential direction and protrudes above the end ring surface of the housing base, in particular in the direction of the axis of rotation. The rim has an inner circumference facing the axis of rotation, which has or is formed by an impact surface running parallel or at an angle to the axis of rotation for deflecting coolant into the cooling channels. Expediently, as mentioned above, coolant is applied, in particular sprayed, to the end ring surface of the housing base during operation of the electrical machine and, since the rotor shaft rotates about the axis of rotation during operation of the electrical machine, is then accelerated radially outwards by the acting centrifugal forces.In this case, the coolant impacts the impact surface of the rim and is deflected by it toward the inlet openings of the cooling channels. Since the inlet openings of the cooling channels are located on an outer edge of the end ring surface of the housing base, which conveniently borders the impact surface of the rim, the coolant can flow into the cooling channels relatively easily.

[0028] Furthermore, it can be provided that the outer peripheral wall has a counter-end ring surface pointing away from the end ring surface of the housing base, in particular opposite the end ring surface of the housing base, and oriented transversely and in particular perpendicularly to the axis of rotation. The cooling channels open, forming inlet openings, at least in sections at the end ring surface of the housing base and at least in sections at the impact surface. Furthermore, the cooling channels open, forming outlet openings, at the counter-end ring surface of the outer peripheral wall. As a result, the inlet openings of the cooling channels are provided at the end ring surface of the housing base and at the impact surface.In this case, it can be provided that the inlet openings of the cooling channels are not flat, as is the case, for example, when the inlet openings of the cooling channels open out at the flat end ring surface of the housing base, but rather have opening sections arranged at an angle to one another, in particular at right angles. The opening sections of the inlet openings arranged on the impact surface can expediently face a direction of rotation of the rotor, in which the rotor shaft rotates about the axis of rotation during operation of the electric machine. In other words, the inlet openings extend sectionally over the end ring surface of the housing base and sectionally over the impact surface of the rim. This allows a relatively large coolant mass flow of coolant to be guided into the inlet openings of the cooling channels.

[0029] In order to improve the deflection of the coolant and the supply of the coolant to the inlet openings of the cooling channels, it can be advantageous in this context if the outer peripheral wall has a counter-end ring surface pointing away from the end ring surface of the housing base, in particular opposite the end ring surface of the housing base, and oriented transversely and in particular perpendicularly to the axis of rotation. A coolant collector structure is arranged on the impact surface of the rim, or the impact surface forms such a coolant collector structure, which is designed to deflect the coolant and supply it to the inlet openings of the cooling channels. The coolant collector structure can ensure optimal flow through the cooling channels even at different and, in particular, relatively high rotor shaft speeds.

[0030] A flow-optimized embodiment of the coolant collector structure can provide for the coolant collector structure to have collector valleys and collector peaks that alternate in the circumferential direction. As a result, the coolant collector structure has an overall wave-like shape. The collector valleys can expediently be assigned to an inlet opening of a cooling channel, and the collector peaks can be arranged circumferentially between two adjacent inlet openings. Furthermore, the collector valleys and the collector peaks are each expediently curved, with a concave side of the collector valleys aligned with the rotational axis and / or a convex side of the collector peaks pointing towards the rotational axis. This has the advantage that coolant can be reliably collected from the end ring surface of the housing base by means of the coolant collector structure and guided to the inlet openings of the cooling channels.

[0031] Furthermore, the deflection of the coolant and the supply of the coolant can be aerodynamically optimized using the coolant collector structure depending on the direction of rotation of the rotor, in which the rotor rotates around the axis of rotation when the electric machine is in operation. For this purpose, the collector peaks can be designed as guide ribs running over the end ring surface of the housing base or can have such guide ribs. In a first variant, the guide ribs can be arranged symmetrically with respect to a radial line running through the axis of rotation and point radially to the axis of rotation. This can ensure optimal deflection and supply of the coolant to the cooling channels, independent of the direction of rotation of the rotor shaft.In an alternative variant, the guide ribs can be designed in a blade-like manner and curved in the opposite direction of rotation of the rotor shaft, in which the rotor rotates around the axis of rotation during operation of the electric machine. This ensures optimal deflection and delivery of the coolant to the cooling channels, dependent on the direction of rotation of the rotor shaft. Overall, coolant can be collected in a targeted manner and in comparatively large mass flows from the end ring surface of the housing base and directed to the inlet openings of the cooling channels.

[0032] Furthermore, the shape of the end ring surface of the housing base can be adapted to reduce the protrusion of said flange. For this purpose, the end ring surface of the housing base can be curved at its outer edge toward the receptacle and otherwise flat. The end ring surface of the housing base thus has an overall dome-shaped configuration. This allows the axial installation space required by the rectifier housing to be kept small.

[0033] It can expediently be provided that the inner circumference of the outer circumferential wall has a plurality of inner circumferential surfaces or is formed by such inner circumferential surfaces. In this case, the inner circumferential surfaces are each flat or have at least one flat component mounting section, with at least one electronic rectifier component being arranged on a respective flat inner circumferential surface or component mounting section of a respective inner circumferential surface. The flat inner circumferential surfaces or the said component mounting sections can each be aligned perpendicularly with respect to a radial running through the axis of rotation, or in other words, normals that are each on the flat inner circumferential surfaces or the said component mounting sections can point radially inward and in particular run through the axis of rotation.This allows the electronic rectifier components to be optimally supported on the inner circumference against centrifugal forces that occur during operation of the electric machine due to the rotation of the rotor around its axis of rotation. This protects the electronic rectifier components from mechanical damage and possible faulty contact. Furthermore, the thermal connection of the electronic rectifier components can be improved due to the increased contact pressure caused by the centrifugal forces.

[0034] Furthermore, it can be provided that the electronic rectifier components are each thermally contacted or connected to the inner circumference, in particular a flat inner circumferential surface of the inner circumference or a component section of an inner circumferential surface of the inner circumference, via a heat-conducting element, in particular a heat-conducting compound, a gap pad, a thermal interface material (TIM) or heat-conducting paste, which can simultaneously serve for electrical insulation from surrounding components.

[0035] Furthermore, it can be provided that recesses for receiving the electronic rectifier components or inserted or molded-on holding frames for receiving the electronic rectifier components are arranged on the inner circumference of the outer circumferential wall, in particular in the region of said flat inner circumferential surfaces or said component-mounting sections of the inner circumferential surfaces. This allows the electronic rectifier components to be easily and securely mounted in a fixed position on the outer circumferential wall.

[0036] It can expediently be provided that the inner circumference of the outer circumferential wall has a plurality of inner circumferential surfaces or is formed by such inner circumferential surfaces, wherein the inner circumferential surfaces are arranged in a prism shape. In other words, the receptacle of the rectifier housing has, or the inner circumferential surfaces thus form, a prism-shaped configuration, wherein a respective base surface of a prism-shaped configuration is preferably polygonal, hexagonal, or octagonal.

[0037] Furthermore, the outer peripheral wall can have a cylindrical, in particular circular-cylindrical, outer periphery. The outer periphery of the outer peripheral wall is expediently located radially opposite the inner periphery of the outer peripheral wall.

[0038] In summary, the present invention preferably relates to an electrical machine with a stator and a rotor shaft mounted thereon so as to be rotatably adjustable about a rotational axis, with a primary coil arranged on the stator and a secondary coil arranged on the rotor shaft, which is inductively coupled to the primary coil during operation of the electrical machine, so that electrical energy is transferred from the primary coil to the secondary coil. Essential to the invention is that the electronic rectifier components of a rectifier device are arranged within a receptacle of a rectifier housing of the rectifier device and are indirectly cooled by cooling channels of the rectifier housing.

[0039] Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures with reference to the drawings.

[0040] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0041] Preferred embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein like reference numerals refer to like or similar or functionally identical components.

[0042] They show, schematically Fig. 1 a highly simplified electrical machine in a side view, Fig. 2 a preferred embodiment of a highly simplified rectifier device in a perspective view, Fig. 3 the rectifier device Fig. 2 in a sectional view running through the axis of rotation, Fig. 4 the rectifier device Fig. 2 in a side view according to a Fig. 3 arrow IV, Fig. 5 a detail of the rectifier device from Fig. 2 in a front view according to a Fig. 2 arrow V, Fig. 6 a detail of another preferred embodiment of a rectifier device, Fig. 7 shows a further preferred embodiment of a highly simplified rectifier device in a perspective view, Fig. 8 the rectifier device from Fig. 7 in a sectional view through the axis of rotation, Fig. 9 shows a further preferred embodiment of a highly simplified rectifier device in a perspective view, wherein a rectifier housing of the rectifier device is shown transparently so that cooling channels of the rectifier device can be seen, Fig. 10 the rectifier device from Fig. 9 in a sectional view according to a Fig. 9 arrow X, Fig. 11 and Fig. 12 each shows a detail of a further preferred embodiment of a rectifier device, Fig. 13 to 18 each show a further preferred embodiment of a highly simplified rectifier device in a sectional view.

[0043] The Fig. 1 shows a side view of a highly simplified electrical machine 1 having a stator 2 (only partially indicated) and a rotor 40 having a rotor shaft 4 mounted on the stator 2 via a rolling bearing 41 so as to be rotatably adjustable about an axis of rotation 3 (indicated by dash-dotted lines). A secondary coil 6 is arranged on the rotor shaft 4 and, during operation of the electrical machine 1, is inductively coupled to a primary coil 5 arranged on the stator 2, so that electrical energy is transferred from the primary coil 5 to the secondary coil 6 without contact.

[0044] The electrical machine 1 further comprises a rectifier device, designated overall by 7, which comprises a rectifier housing 8 and electronic rectifier components 9 for converting an alternating electrical voltage generated in the secondary coil 6 during the inductive energy transfer into a direct electrical voltage.

[0045] The rectifier housing 8 has an annular housing base 10 which is oriented perpendicular to the axis of rotation 3 and concentric with the axis of rotation 3 and has a through-opening 11. The rotor shaft 4 is pushed through the through-opening 11 of the rectifier housing 8 and the rectifier housing 8 is pressed onto the rotor shaft 4 such that the rectifier housing 8 is connected to the rotor shaft 4 in a rotationally and axially fixed manner. The rectifier housing 8 also has an outer peripheral wall 13 which projects integrally from the housing base 10, is parallel with the axis of rotation 3, perpendicular to the housing base 10 and concentric with the axis of rotation 3. The outer peripheral wall 13 has an inner circumference 14 which faces the axis of rotation 3, i.e. which faces radially inwards. A receptacle 15 of the rectifier housing 8 is arranged transversely, and in particular radially, with respect to the axis of rotation 3 between the inner circumference 14 of the outer peripheral wall 13 and the axis of rotation 3.

[0046] Furthermore, the housing base 10 has an end ring surface 20 pointing away from the receptacle 15 and oriented perpendicularly to the axis of rotation 3, and the outer peripheral wall 13 has a counter end ring surface 21 pointing away from the end ring surface 20 of the housing base 10, opposite the end ring surface 20 of the housing base 10 and oriented perpendicularly to the axis of rotation 3.

[0047] In Fig. 1 further shows that the electronic rectifier components 9 are evenly distributed in a circumferential direction 16 around the rotation axis 3, are arranged within said receptacle 15, supported on the inner circumference 14 of the outer circumferential wall 13, and that the rectifier housing 8 further comprises cooling channels 17. To achieve indirect cooling of the electronic rectifier components 9, it is provided in the present case that the cooling channels 17 can be flowed through by coolant 18 in a flow direction 42 indicated by arrows.

[0048] The Fig. 2 to 5 show a preferred embodiment of a highly simplified rectifier device 7. In particular, in Fig. 3 that the said cooling channels 17 run exclusively through the outer peripheral wall 13 and that the cooling channels 17 are each designed as longitudinal channels 19 which pass through the outer peripheral wall 13 parallel to the axis of rotation 3.

[0049] With regard to the cooling channels 17 and the longitudinal channels 19, it should be explained that they each open out at least in sections at an outer edge 24 of the end ring surface 20 of the housing base 10, forming an inlet opening 23, and downstream at the counter-end ring surface 21 of the outer peripheral wall 13, forming outlet openings 25.

[0050] The coolant 18 is applied, in particular sprayed, onto the end ring surface 20 of the housing base 10 during operation of the electrical machine 1, for example using a spray nozzle 43. Since the rotor 40 or the rotor shaft 4 rotates in the direction of rotation 16 about the axis of rotation 3 during operation of the electrical machine 1, the coolant 18 is then accelerated in a spiral radially outwardly towards the edge 24 of the end ring surface 20 by the acting centrifugal forces 39, as shown in particular in Fig. 2 is shown.

[0051] Since the inlet openings 23 of the cooling channels 17 are arranged on the outer edge 24 of the end ring surface 20, the coolant 18 can flow relatively easily into the cooling channels 17 via the end ring surface 20 and via the inlet openings 23. The end ring surface 20 thus serves, so to speak, on the one hand as a collecting surface for the coolant 18 and, on the other hand, as a guide surface along which the coolant 18 is guided and accelerated radially outward.

[0052] Especially in Fig. 4 to 6, it can be seen that the cooling channels 17 are arranged within the outer circumferential wall 13 so as to be evenly distributed relative to one another in the circumferential direction 16, and that exactly two cooling channels 17 are assigned to each electronic rectifier component 9. The coolant 18, which flows through two such cooling channels 17 assigned to an electronic rectifier component 9, is in a greater heat exchange with this electronic rectifier component 9 than with an adjacent, further electronic rectifier component 9.

[0053] In Fig. 3 it can be seen that the cooling channels 17 taper in the direction of the rotation axis 3, so that the said inlet openings 23 of the cooling channels 17 each have an inlet opening cross-sectional area which is smaller in area than the outlet opening cross-sectional areas of the opposite outlet openings 25.

[0054] In the Fig. 2 to 6, it can also be clearly seen that the housing base 10 has a rim 28. The rim 28 completely surrounds the end ring surface 20 of the housing base 10 radially outward in the circumferential direction 16 and projects upwards beyond the end ring surface 20 of the housing base 10 in the direction of the rotation axis 3. The rim 28 thereby encloses the end ring surface 20 like a fence. The rim 28 has an inner circumference 29 facing the rotation axis 3, which has or is formed by an impact surface 30 running parallel or at an angle to the rotation axis 3 for deflecting coolant 18 into the cooling channels 17. The coolant 18 sprayed onto the end ring surface 20 during operation of the electric machine 1 can thus impact the impact surface 30 of the rim 28 and be deflected in the direction of the inlet openings 23 of the cooling channels 17, so that the coolant 18 reaches the cooling channels 17 via the inlet openings 23.Since the inlet openings 23 of the cooling channels 17 are arranged on the outer edge 24 of the end ring surface 20, the coolant 18 can flow into the cooling channels 17 relatively easily and with a comparatively large mass flow.

[0055] In order to improve the deflection and guidance of the coolant 18 to the inlet openings 23 of the cooling channels 17, it is provided, by way of example, that a coolant collector structure 31 is formed on the impact surface 30 of the rim 28, which is designed to deflect and guide the coolant 18 to the inlet openings 23 of the cooling channels 17, or that the impact surface 30 forms the same. The coolant collector structure 31 is characterized in particular by collector valleys 32 and collector peaks 33 alternating in the circumferential direction 16, see in particular the Fig. 5 and Fig. 6. The collector valleys 32 are each spatially assigned to an inlet opening 23 of a cooling channel 17, and the collector peaks 33 are arranged in the circumferential direction 16 between two adjacent inlet openings 23. The collector valleys 32 and collector peaks 33 are further each bent or curved, with concave sides 44 of the collector valleys 32 pointing toward the rotation axis 3 and convex sides 45 of the collector peaks 33 pointing toward the rotation axis 3.

[0056] Furthermore, in Fig. 5 and Fig. 6, it is provided that the deflection and guidance of the coolant 18 to the inlet openings 23 is carried out by means of the coolant collector structure 31 depending on the direction of rotation 16 of the rotor 40 or the rotor shaft 3. Thus, in Fig. 5, the deflection and guidance of the coolant 18 to the inlet openings 23 is designed independently of the direction of rotation 16 of the rotor 40 or the rotor shaft 3, in that the collector peaks 33 are realized as guide ribs 34 extending over the end ring surface 20 of the housing base 10, which are each arranged symmetrically with respect to a radial 35 running through the axis of rotation 3 and point radially to the axis of rotation 3. Alternatively, the guide ribs 34 can be designed as in Fig. 6, each of them can be designed in a blade-like manner and bent or curved counter to the direction of rotation 36 of the rotor 40 or the rotor shaft 4. This ensures a flow 42 through the cooling channels 17 that depends on the direction of rotation 16 of the rotor shaft 4.

[0057] With regard to the rectifier housing 8, in particular with regard to Fig. 3 and Fig. 4, it should be explained that the inner circumference 14 of the outer circumferential wall 13 has a plurality of inner circumferential surfaces 37. These inner circumferential surfaces 37 each have a flat mounting section 38 for mounting at least one electronic rectifier component 9, wherein in the present case, an electronic rectifier component 9 is fixed to each mounting section 38 of an inner circumferential surface 37 via a heat-conducting element 46. The heat-conducting elements 46 can each be formed by a heat-conducting compound, a gap pad, a thermal interface material (TIM), or thermal paste.

[0058] In Fig. 7 to 10 show further preferred embodiments of a highly simplified rectifier device 7 in a perspective view. It differs from the previously described embodiment in particular in that the cooling channels 17 are designed as intertwined, cylindrically spiral-shaped helical channels 22, which also open out, forming inlet openings 23, both in sections at the end ring surface 20 of the housing base 10 and in sections at the impact surface 30, and open out downstream, forming outlet openings 25 at the counter-end ring surface 21 of the outer peripheral wall 13.

[0059] The Fig. 13 shows a further preferred embodiment of a highly simplified rectifier device 7 in a sectional view, wherein it can be seen that coolant 18 is sprayed onto the end ring surface 20 of the housing base 10 by means of a spray nozzle 43 and is then accelerated radially outward onto the impact surface 30 of the rim 28 due to the rotation of the rotor 40 or the rotor shaft 4 about the rotation axis 3. The coolant 18 is deflected by the impact surface 30 into the cooling channels 17 (not illustrated here). The end ring surface 20 of the housing base 10 is completely flat here.

[0060] The Fig. 14 shows a further preferred embodiment of a highly simplified rectifier device 7 in a sectional view, wherein it can be seen that the flat component sections 38 of the inner circumferential surfaces 37 are angularly tilted with respect to the rotation axis 3 and merge into a rear surface 47 of the housing base 10 facing the receptacle 15. As a result, the electronic rectifier components 9, which are arranged on the component sections 38, are angularly tilted with respect to the rotation axis 3.

[0061] The Fig. 15 shows a further preferred embodiment of a highly simplified rectifier device 7 in a sectional view, wherein it can be seen that the flat component mounting sections 38 of the inner circumferential surfaces 37 are angularly tilted with respect to the rotation axis 3 and merge into a rear surface 47 of the housing base 10 facing the receptacle 15. As a result, the electronic rectifier components 9 arranged on the component mounting sections 38 are angularly tilted with respect to the rotation axis 3. Furthermore, a circuit board 48 is arranged on the rear surface 47 of the housing base 10 and is connected to the electronic rectifier components 9 via wires 49 or the like.

[0062] The Fig. 16 shows a further preferred embodiment of a highly simplified rectifier device 7 in a sectional view, wherein it can be seen that the flat component sections 38 of the inner circumferential surfaces 37 are angularly tilted with respect to the rotation axis 3 and merge into a rear surface 47 of the housing base 10 facing the receptacle 15. As a result, the electronic rectifier components 9 arranged on the component sections 38 are angularly tilted with respect to the rotation axis 3.

[0063] The Fig. 17 and Fig. 18 show a further preferred embodiment of a highly simplified rectifier device 7 in a sectional view, wherein it can be seen that the end ring surface 20 of the housing base 10 is tilted at an angle in order to reduce the axial projection of the said rim 28. As a result, the end ring surface 20 has an approximately dome shape. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 28 19 824 C2 [0006, 0007] DE 10 2015 014 535 A1

[0007] US 2006 / 0176720 A1

[0007]

Claims

[1] Electrical machine (1), in particular a separately excited synchronous electrical machine, - with a stator (2) and a rotor (40) mounted on the same so as to be rotatably adjustable about a rotational axis (3) and having a rotor shaft (4), - with a primary coil (5) arranged on the stator (2) and a secondary coil (6) arranged on the rotor shaft (4), which is inductively coupled to the primary coil (5) during operation of the electrical machine (1), so that electrical energy is transferred from the primary coil (5) to the secondary coil (6), - with a rectifier device (7) which has a rectifier housing (8) arranged on the rotor shaft (4) and electronic rectifier components (9) for converting an electrical alternating voltage generated in the secondary coil (6) during the inductive energy transfer into an electrical direct voltage, - wherein the rectifier housing (8) has an annular housing base (10) aligned transversely to the axis of rotation (3) and concentric with respect to the axis of rotation (3) with a through-opening (11) for receiving the rotor shaft (4) and an outer peripheral wall (13) projecting axially away from the housing base (10) with respect to the axis of rotation (3) and concentric with respect to the axis of rotation (3) with an inner circumference (14) facing the axis of rotation (3), - wherein the rectifier housing (8) further comprises a receptacle (15) arranged transversely with respect to the axis of rotation (3) between the inner circumference (14) of the outer circumferential wall (13) and the axis of rotation (3), characterized by , that - the electronic rectifier components (9) are arranged within the receptacle (15) of the rectifier housing (8) in a circumferential direction (16) around the axis of rotation (3) evenly distributed on the inner circumference (14) of the outer circumferential wall (13), - the rectifier housing (8) has cooling channels (17) through which coolant (18) can flow to achieve indirect cooling of the electronic rectifier components (9). [2] Electrical machine (1) according to claim 1, characterized by , that - the cooling channels (17) run through the outer peripheral wall (13). [3] Electrical machine (1) according to claim 1 or 2, characterized by , that - the cooling channels (17) are designed as longitudinal channels (19) which pass through the outer peripheral wall (13) parallel to the axis of rotation (3). [4] Electrical machine (1) according to claim 1 or 2, characterized by , that - the cooling channels (17) are designed as helical channels (22) which pass through the outer peripheral wall (13) in a cylindrical spiral shape and coaxially to the axis of rotation (3). [5] Electrical machine (1) according to one of the preceding claims, characterized by , that - the housing base (10) has a front ring surface (20) pointing away from the receptacle (15) and oriented transversely to the axis of rotation (3), - the outer peripheral wall (13) has a counter-end ring surface (21) pointing away from the end ring surface (20) of the housing base (10) and oriented transversely to the axis of rotation (3), - the cooling channels (17) open out at least in sections at an outer edge (24) of the end ring surface (20) of the housing base (10) to form inlet openings (23) and at the counter-end ring surface (21) of the outer peripheral wall (13) to form outlet openings (25). [6] Electrical machine (1) according to one of the preceding claims, characterized by , that - the cooling channels (17) are arranged within the outer peripheral wall (13) in a uniformly distributed manner relative to one another in the circumferential direction (16). [7] Electrical machine (1) according to one of the preceding claims, characterized by , that - each electronic rectifier component (9) is assigned exactly two cooling channels (17), in such a way that the coolant (18) flowing through two such cooling channels (17) assigned to an electronic rectifier component (9) is in a greater heat exchange with this electronic rectifier component (9) than with an adjacent, further electronic rectifier component (9). [8] Electrical machine (1) according to one of the preceding claims, characterized by , that - the cooling channels (17) taper in the direction of the axis of rotation (3). [9] Electrical machine (1) according to one of the preceding claims, characterized by , that - the housing base (10) has a front ring surface (20) pointing away from the receptacle (15) and oriented transversely to the axis of rotation (3), - the housing base (10) further comprises a rim (28) which completely surrounds the end ring surface (20) of the housing base (10) radially outward in the circumferential direction (16) and projects upwards above the end ring surface (20) of the housing base (10), - wherein the rim (28) has an inner circumference (29) facing the axis of rotation (3), which has or is formed by an impact surface (30) running parallel or at an angle to the axis of rotation (3) for deflecting coolant (18) into the cooling channels (17). [10] Electrical machine (1) according to claim 9, characterized by , that - the outer peripheral wall (13) has a counter-end ring surface (21) pointing away from the end ring surface (20) of the housing base (10) and oriented transversely to the axis of rotation (3), - the cooling channels (17) open out at least partially at the end ring surface (20) of the housing base (10) and at least partially at the impact surface (30), forming inlet openings (23), - the cooling channels (17) open out to form outlet openings (25) on the counter-end ring surface (21) of the outer peripheral wall (13). [11] Electrical machine (1) according to claim 9 or 10, characterized by , that - the outer peripheral wall (13) has a counter-end ring surface (21) pointing away from the end ring surface (20) of the housing base (10) and oriented transversely to the axis of rotation (3), - a coolant collector structure (31) designed to deflect and guide the coolant (18) to the inlet openings (23) of the cooling channels (17) is arranged on the impact surface (30) of the rim (28) or the impact surface (30) forms such a coolant collector structure (31). [12] Electrical machine (1) according to claim 11, characterized by , that - the coolant collector structure (31) has collector valleys (32) and collector peaks (33) which alternate in the circumferential direction (16). [13] Electrical machine (1) according to claim 12, characterized by , that - the collector peaks (33) are designed as guide ribs (34) extending over the end ring surface (20) of the housing base (10) or have such guide ribs (34), - wherein the guide ribs (34) are each arranged symmetrically with respect to a radial (35) running through the axis of rotation (3) and point radially to the axis of rotation (3), or - wherein the guide ribs (34) are each designed in a blade-like manner and are curved counter to a direction of rotation (36) of the rotor shaft (4), in which direction the rotor shaft (4) rotates about the axis of rotation (3) during operation of the electrical machine (1). [14] Electrical machine (1) according to one of the preceding claims, characterized by , that - the inner circumference (14) of the outer circumferential wall (13) has a plurality of inner circumferential surfaces (37) or is formed by such inner circumferential surfaces (37), - wherein the inner peripheral surfaces (37) each have a flat mounting section (38) with at least one electronic rectifier component (9) arranged thereon, - wherein the assembly sections (38) are each aligned perpendicularly with respect to a radial (35) running through the axis of rotation (3). [15] Electrical machine (1) according to one of the preceding claims, characterized by , that - the inner circumference (14) of the outer circumferential wall (13) has a plurality of inner circumferential surfaces (37) or is formed by such inner circumferential surfaces (37), - wherein the inner peripheral surfaces (37) are arranged in a prism shape.

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