Tubular insulation layer for primary coil of a contactless transformer for an external excited synchronous machine

Abstract

This invention relates to a primary coil of a non-contact transformer for an externally excited synchronous motor, comprising a ferrite core configured as a hollow cylinder with a slotted groove on its radially outer side for accommodating a winding; a winding disposed within the slotted groove, having a radially inner cylindrical surface and a radially outer cylindrical surface, a first axial side, and a second axial side opposite to the first axial side; and a tubular insulating layer disposed on the radially inner cylindrical surface between the winding and the slotted groove, covering the winding on the first axial side and the second axial side; wherein the tubular insulating layer forms a first portion extending along the radially outer cylindrical surface of the winding at least in a partial axial section from the first axial side; and the tubular insulating layer forms a second portion extending along the radially outer cylindrical surface of the winding at least in a partial axial section from the second axial side. The invention also relates to a non-contact transformer, an externally excited synchronous motor, and a method for manufacturing a primary coil of a non-contact transformer for an externally excited synchronous motor.

Description

[0001] The present invention relates to a primary coil of a non-contact transformer for an externally excited synchronous motor, comprising a ferrite core, a winding, and a tubular insulating layer disposed on a radially inner cylindrical surface between the winding and a slotted groove.

[0002] The present invention also relates to a non-contact transformer, an externally excited synchronous motor, and a method for manufacturing the primary coil of a non-contact transformer for an externally excited synchronous motor.

[0003] In motor vehicles, electric motors are increasingly being used as drive systems to replace internal combustion engines that require fossil fuels. Significant efforts have been made to improve the everyday usability of electric drives and provide users with a familiar driving experience.

[0004] In addition to purely electric drive systems, hybrid drive systems are also known. These hybrid vehicles typically combine an internal combustion engine and an electric motor, enabling pure electric operation, for example, in urban areas while still providing sufficient range and availability for intercity travel. Furthermore, under certain operating conditions, both the internal combustion engine and the electric motor can drive the vehicle simultaneously.

[0005] In the development of electric motors, particularly for those used in E-axis or hybrid modules, there is a persistent need to improve power density and efficiency while reducing manufacturing costs. Against this backdrop, it is known to construct externally excited synchronous motors (FSMs) from electric motors. In an FSM, the electrical power used to excite the rotor windings must be transferred to the rotor. For traction motors, contact transformers are typically used for this purpose. When these windings are energized, a magnetic field is generated, which interacts with the stator magnetic field to produce torque. The strength of the rotor magnetic field can be adjusted by the magnitude of the excitation current. Thus, the machine's operating behavior can always be adjusted in an efficiency-optimized manner according to its specific operating conditions.

[0006] The disadvantages of this type of contact transformer are that the contact between stationary and rotating parts introduces mechanical and electrical losses. Further disadvantages include wear and tear on the rubbing parts, resulting in abrasive debris contamination, and a relatively large installation space requirement.

[0007] As an alternative to this type of contact transformer, non-contact induction transformers are also known, for example. Induction transformers are typically rotationally symmetric transformers with an air gap, consisting of primary and secondary coils. Typically, induction transformers also have a magnetic core, for example, made of ferrite. This magnetic core can be made from one or more components.

[0008] For example, all components of the core can be fixed to the stationary side of the motor, with the secondary winding rotating inside the core. Alternatively, the core components can be fixed to a rotating part of the machine. In this case, the primary and secondary core components are separated by an air gap. This air gap must be large enough that the core components do not come into contact with each other, taking into account all tolerances and operating conditions. To withstand the rotational speed, the rotating transformer components are typically strapped or assembled into other components. An example of such an implementation can be found in DE 10 2017 214 776 A1 or DE201210201826 A1.

[0009] A non-contact transformer, such as those used in externally excited synchronous motors, is essentially a transformer consisting of a primary section or primary coil and a secondary section or secondary winding. This structure allows alternating current to be transmitted based on electromagnetic induction. Alternatively, the term "induction transformer" can be used. For example, when a single-phase alternating current is applied to the primary section, a magnetic field is generated in the primary coil winding, which in turn induces a single-phase alternating current in the secondary coil winding. The secondary voltage can be set according to the number of turns in the primary and secondary windings and the primary voltage. The magnitude of the primary voltage and the number of turns vary depending on the application. In some cases, the primary voltage is significantly higher than the secondary voltage, which leads to higher requirements for insulation.

[0010] Coil insulation is particularly important in high-voltage applications, such as those required for externally excited synchronous motors in the automotive industry. Insufficient insulation can lead to breakdown or partial discharge within the system, potentially causing system failure. A key aspect of coil insulation is interlayer insulation. Due to voltage drops in the copper wire, the dielectric strength of the enameled wire may become insufficient, necessitating additional insulation between the conductor layers. Current technology utilizes conventional sheet insulation materials such as paper or film. These sheet insulation materials are primarily used for two-dimensional insulation. To achieve continuous 360-degree insulation, individual sheet insulation material components must be bonded together at adhesive points.

[0011] Therefore, the object of the present invention is to provide a primary winding for a non-contact energy transfer device or a non-contact transformer for an externally excited synchronous motor rotor, particularly in a motor vehicle drivetrain, which possesses a compact structure and high operational reliability even when high power transmission is required. In particular, it relates to the primary winding of a non-contact transformer for an externally excited synchronous motor. Furthermore, another object of the present invention is to provide a method for manufacturing the corresponding primary winding.

[0012] This task is achieved through the following scheme: a primary coil of a non-contact transformer for an externally excited synchronous motor, comprising a ferrite core configured as a hollow cylinder, the ferrite core having a slotted groove on its radially outer side for accommodating a winding. The primary coil further includes a winding disposed within the slotted groove, having a radially inner cylindrical surface and a radially outer cylindrical surface, a first axial side and a second axial side opposite to the first axial side. The primary winding also includes a tubular insulating layer disposed on the radially inner cylindrical surface between the winding and the slotted groove, and covering the winding on the first axial side and the second axial side. The tubular insulating layer forms a first portion extending along the radially outer cylindrical surface of the winding at least in a partial axial section from the first axial side. The tubular insulating layer also forms a second portion extending along the radially outer cylindrical surface of the winding at least in a partial axial section from the second axial side.

[0013] Advantageously, the tubular insulating layer extends from the radially inner cylindrical surface, covering the winding in the direction from the first axial side to the second axial side and / or from the second axial side to the first axial side, thereby increasing the creepage distance. Creepage distance is the shortest distance between two conductive components along the surface of a solid insulating material.

[0014] Of particular advantage is that the tubular insulating layer integrally forms continuous insulation between the winding and the ferrite, thereby reducing the risk of short circuits.

[0015] As an alternative to ferrite cores, cores made of other hard or soft magnetic materials can be used.

[0016] First, the various elements of the inventive subject matter described in the claims are explained in accordance with their importance or the order of mention in the set of claims, and then particularly preferred embodiments of the inventive subject matter are described.

[0017] The rotor is the rotating component of an electric motor. The rotor specifically includes a rotor shaft. The rotor shaft can be hollow, which reduces weight and allows lubricating or cooling media to be delivered to the rotor body.

[0018] The motor can be specifically configured as a rotary motor. The rotary motor can be specifically configured as a radial flux motor. A radial flux motor is characterized in that the magnetic field lines in the air gap formed between the rotor and stator extend radially. The air gap refers to the gap that exists between the rotor and stator. In a radial flux motor, this air gap is annular in cross-section, and its radial width corresponds to the distance between the rotor body and the stator body.

[0019] This motor is particularly suitable for use in the drivetrain systems of hybrid or pure electric vehicles. Specifically, the motor's dimensions are configured to achieve vehicle speeds greater than 50 km / h, preferably greater than 80 km / h, and especially greater than 100 km / h. Particularly preferably, the motor's power is greater than 50 kW, preferably greater than 80 kW, and especially greater than 150 kW. Furthermore, it is preferable that the motor provides a speed greater than 8,000 U / min, particularly preferably greater than 12,000 U / min, and most preferably greater than 1500 U / min.

[0020] Motor vehicles as referred to in this application include land vehicles that are mechanically powered and do not rely on tracks. Motor vehicles may be selected from, for example, the following groups: passenger cars (PKW), trucks (LKW), mopeds, light motor vehicles, motorcycles, buses (KOM), or tractor-trailers.

[0021] A non-contact transformer, such as those used in externally excited synchronous motors, is essentially composed of a primary and a secondary section, much like a traditional transformer. This structure allows alternating current to be transmitted based on electromagnetic induction. Alternatively, the term "induction transformer" can be used. For example, when a single-phase alternating current is applied to the primary section, a magnetic field is generated in the primary winding, which in turn induces a single-phase alternating current in the secondary winding. The secondary voltage can be set according to the number of turns in the primary and secondary sections and the primary voltage. The magnitude of the primary voltage and the number of turns vary depending on the application. In some cases, the primary voltage is significantly higher than the secondary voltage, which leads to higher requirements for insulation.

[0022] The induction transformer can be arranged inside a hollow shaft. The hollow shaft can be made as a single piece or a multi-piece structure. In principle, it is conceivable that the hollow shaft is completely or only partially penetrated by an opening along its length. For example, it is also conceivable that the hollow shaft has a blind hole into which the induction transformer can then be inserted. Preferably, the hollow shaft is formed of a metallic material, especially steel.

[0023] The induction transformer is configured to transmit power, preferably greater than 1 kW and more preferably greater than 2 kW, for at least a short period of time without overloading the transformer electrically or thermally. Most preferably, the induction transformer is configured to transmit power between 0.5 kW and 10 kW, preferably between 1 kW and 5 kW, and more preferably between 2 kW and 4 kW.

[0024] The transformer windings are made of a highly conductive but non-ferromagnetic material (e.g., copper or aluminum) and are electrically insulated from each other. Preferably, the windings are arranged tangentially around a hollow shaft, forming a hollow cylindrical winding body with an axial length and a diameter. Most preferably, the windings are wound on and / or located on and / or within a magnetic core made of a ferromagnetic material.

[0025] The winding can be composed of one or more electrical conductors with a circular cross-section. Alternatively, the conductors constituting the winding may have a cross-sectional shape that deviates from a circle, particularly being rectangular. Particularly preferred is that the winding can be composed of insulating copper foil, which can be wound together in a manner similar to a toilet paper roll.

[0026] According to an advantageous improvement of the invention, the primary coil winding can have more turns than the secondary coil winding. Therefore, when transferring electrical energy between the primary and secondary coils, the relatively high battery voltage can be simultaneously converted to a lower rotor voltage.

[0027] In this context, it is further preferred that a voltage of 40–1500 V be present on the primary coil, more preferably 100–1000 V, and most preferably 300–850 V. Furthermore, in this context, it is also preferred that a voltage of 70–500 V be present on the secondary coil.

[0028] The primary and / or secondary magnetic cores are made of ferromagnetic materials, preferably ferrite materials. The primary and / or secondary magnetic cores can be configured in multiple parts. Each core component is preferably constructed to be largely rotationally symmetric, but may include elements and grooves for fixing or guiding other components.

[0029] Particularly preferred is that the primary core and / or secondary core each have an annular spatial shape. Most preferred is that the primary core and / or secondary core have a U-shaped cross-sectional profile with circumferential slots. Preferably, the slots in the U-shaped cross-sectional profiles of the primary and secondary cores face each other. Particularly preferred is that the primary winding is located within a slot in the primary core and / or the secondary winding is located within a slot in the secondary core.

[0030] The axial length of the hollow cylindrical secondary winding is preferably greater than 50% of the radial outer diameter, more preferably greater than 70%, and especially greater than 70% of the secondary winding diameter. This "slender" winding structure has proven particularly advantageous for energy transfer in induction transformers. In short, the flat and slender design of the hollow cylindrical secondary winding has proven especially advantageous in terms of the energy transfer characteristics of induction transformers.

[0031] Furthermore, the preferred option is that the axial length of the hollow cylindrical primary coil corresponds to 80% to 120% of the axial length of the hollow cylindrical secondary coil, which also contributes to good energy transfer between the primary and secondary windings.

[0032] Furthermore, it is advantageous that the axial lengths of the two hollow cylindrical coils completely overlap in the axial direction, thereby further optimizing the energy transfer between the primary and secondary coils.

[0033] Furthermore, it is advantageous for the primary and secondary magnetic cores to each form adjacent air gaps, which serve to guide magnetic flux from one to the other. If the surface of the primary core's adjacent air gap completely covers the surface of the secondary core's adjacent air gap, and / or if the surface of the secondary core's adjacent air gap completely covers the surface of the primary core's adjacent air gap, energy transfer between the primary and secondary windings can be further optimized.

[0034] In the context of this application, a tubular insulating layer is a flexible tubular object composed of a three-dimensional solid insulating material. The insulating material is characterized by being composed of a non-conductive material, i.e., possessing only extremely low, and therefore negligible, electrical conductivity. Insulating materials are used in electrical engineering to confine current to live parts. The solid insulating material preferably shrinks significantly under heat and / or exhibits flexible properties, and therefore preferably can also stretch under heat.

[0035] Heat shrink tubing is a thermoplastic tubing that shrinks significantly in the radial direction when heated (e.g., by a heat gun). Heat shrink tubing is used for insulation, mechanical protection, or sealing. It is particularly made of materials such as polyolefins, polyvinylidene fluoride (PVDF), Viton, polyvinyl chloride (PVC), and polytetrafluoroethylene (PTFE or Teflon).

[0036] Implementation method: According to one embodiment, the lead wire of the winding extends from the first axial side to the second axial side along the radially outer cylindrical surface. Further, a second portion of the tubular insulating layer is disposed between the winding and the lead wire from the second axial side toward the first axial side. Additionally, a first portion of the tubular insulating layer covers at least a portion of the lead wire and the winding on the radially outer cylindrical surface from the first axial side toward the second axial side.

[0037] The advantage of this embodiment is that the tubular insulation layer, which radially covers the winding from the inner cylindrical surface in the first axial direction to the second axial direction and / or from the second axial direction to the first axial direction, does not need to be interrupted; in other words, there is no need to provide through holes for the leads in the insulation layer. Therefore, the leads are initially located below the first portion of the tubular insulation layer in the first axial direction. In the second portion of the tubular insulation layer, the leads are located above the tubular insulation layer. Thus, the arrangement of the leads and the combination with the tubular insulation layer do not negatively affect the creepage distance.

[0038] According to another embodiment, a first portion and a second portion of the tubular insulating layer at least partially overlap axially on the radially outer cylindrical surface of the winding.

[0039] This allows for a particularly advantageous insulation that completely encloses the windings, thereby maximizing the creepage distance.

[0040] According to another embodiment, the tubular insulating layer is composed of a plurality of tubular insulating layers, which overlap each other axially on the radial inner cylindrical surface of the winding in the groove region.

[0041] This allows for a design suitable for assembly, because the ferrite core is not located at the axial center of a single tubular insulating layer, but rather each tubular insulating layer can be fitted onto the ferrite core from its respective axial direction. This helps simplify the automated handling of the ferrite core.

[0042] According to a particularly preferred embodiment, the tubular insulating layer is a heat shrink tubing.

[0043] When using heat shrink tubing, the shrinkage process allows for a better fit to the edges and corners of the insulated components. This enables the windings to be placed into the slots of the ferrite core with the highest possible fill factor. Particularly preferred is the elimination of additional bonding or setting of bonding points, as with sheet insulation materials. This translates to cost savings and avoids potential defects in the insulation, thereby maximizing creepage distance and reducing the risk of short circuits.

[0044] According to another embodiment, the winding is configured as Litz wire, particularly copper Litz wire.

[0045] Of particular advantage is that the Litz wire is a high-frequency Litz wire, also known as an HF-Litz wire. The HF-Litz wire consists of a large number of fine conductors, which are typically insulated from each other by varnish and twisted together in such a way that, on average, each single conductor appears as many times as possible at each position in the total cross-section of the Litz wire. High-frequency Litz wire can compensate for eddy currents, thereby improving efficiency. Another advantage of high-frequency Litz wire is its better thermal conductivity, and high-frequency losses are also reduced.

[0046] According to one embodiment, the ferrite core has an axially extending groove on its radially outer side for allowing the lead wire of the winding to be axially led out from the groove to the end face.

[0047] The advantage of axially extending grooves is that the lead wires do not extend radially beyond the ferrite core. This allows for optimized spatial arrangement of the primary coil relative to the secondary coil, as it allows for optimal air gap positioning between them.

[0048] According to another aspect, a non-contact transformer for an externally excited synchronous motor includes a primary coil according to any of the above aspects or embodiments. The non-contact transformer also includes a secondary coil arranged coaxially with the primary coil and forming a radial air gap.

[0049] According to another aspect, an externally excited synchronous motor includes a non-contact transformer or primary coil according to any of the above aspects or embodiments.

[0050] According to another aspect, a method for manufacturing a primary coil of a contactless transformer for an externally excited synchronous motor, wherein the primary coil has a tubular insulating layer, includes the following steps: a) Provide a hollow cylindrical ferrite core having slotted grooves on its radially outer side for accommodating windings. b) Provide several mounting bushings designed as thin-walled hollow cylindrical components, the inner diameter of which is selected to substantially correspond to the outer diameter of the ferrite core, allowing the mounting bushings to be axially fitted onto the outer diameter of the ferrite core. c) A tubular insulating layer is provided, the inner diameter of which allows the tubular insulating layer to be fitted onto the mounting bushing and the ferrite core, and the axial length of the tubular insulating layer is greater than the axial length of the ferrite core. d) The mounting bushings are positioned on two opposite axial sides of the ferrite core, and the tubular insulating layer is positioned so that it extends axially beyond the ferrite core on both axial sides of the ferrite core. e) Applying a winding to the slotted groove region, wherein the lead wire of the winding extends radially on the first axial side of the slotted groove corresponding to the first axial side of the winding. f) The mounting bushing, located on the second axial side opposite to the first axial side, is pushed axially so that the mounting bushing pushes the tubular insulation layer over the winding from the second axial side toward the first axial side. g) Lay the lead wires of the winding on the area of ​​the pushed-over tubular insulation layer. h) The mounting bushing disposed on the first axial side is pushed axially so that the mounting bushing pushes the tubular insulation layer over the winding from the first axial side toward the second axial side and at least partially covers the lead wire.

[0051] Of particular advantage is that the tubular insulating layer is composed of multiple tubular insulating layers that overlap axially on the radially inner cylindrical surface of the winding in the slotted region. This allows for a design suitable for assembly, because the ferrite core is not located at the axial center of a single tubular insulating layer, but rather each tubular insulating layer can be fitted onto the ferrite core from its respective axial direction. This facilitates the automated handling of the ferrite core.

[0052] According to an advantageous embodiment, the tubular insulating layer is a heat-shrink tubing, and the method further includes the following steps: d1) The tubular insulating layer is thermally shrunk onto the ferrite core in the grooved region. f1) The tubular insulation layer to be pushed onto the winding is thermally shrunk in the grooved area. h1) The tubular insulation layer to be pushed over is heat-shrinked to the winding and the lead wire in the grooved area, wherein Step d1) is executed after step d). Step f1) is executed after step f). And perform step h1) after step h).

[0053] When using heat shrink tubing, the shrinkage process allows for a better fit to the edges and corners of the insulated components. This enables the windings to be placed into the slots of the ferrite core with the highest possible fill factor. Particularly preferred is the elimination of additional bonding or setting of bonding points, as with sheet insulation materials. This translates to cost savings and avoids potential defects in the insulation, thereby maximizing creepage distance and reducing the risk of short circuits.

[0054] According to an advantageous embodiment, a vacuum is applied in step d1) and / or step f1) and / or step h1).

[0055] Applying a vacuum during heat shrinking has the advantage of preventing gas entrainment. In particular, it prevents gas entrainment between the insulation layer and the ferrite core, and between the insulation layer and the windings. Furthermore, applying a vacuum advantageously allows the tubular insulation layer or heat shrink tubing to better conform to the ferrite core and / or windings and leads. Thus, especially when using heat shrink tubing, the edges and corners of the insulated components can be reproduced more accurately.

[0056] According to an advantageous embodiment, in step h), the tubular insulating layer is pushed onto at least the radial outer cylindrical surface of the winding to form a partial double-layer overlap.

[0057] This allows for a particularly advantageous insulation that completely encloses the windings, thereby maximizing the creepage distance.

[0058] The present invention and its technical background will now be described in more detail with reference to the accompanying drawings. It should be noted that the present invention should not be limited to the embodiments shown. In particular, unless otherwise explicitly stated, certain aspects of the content illustrated in the drawings may be extracted and combined with other components and understandings in this specification and / or the drawings. It should be particularly noted that the drawings, especially the scale shown, are merely schematic. The same reference numerals denote the same objects, and therefore, supplementary descriptions in other drawings may be used where necessary. Terms such as "radial" and "axial" refer to the rotating shaft of the motor unless a different reference is explicitly adopted. Furthermore, to improve readability, reference numerals may be used only for some or a few identical elements.

[0059] It is shown below: Figure 1. Cross-sectional view of the primary coil of the non-contact transformer for an externally excited synchronous motor. Figure 2 Figure 1 The diagram shows a cross-sectional view of the primary coil during the first assembly step.

[0060] Figure 3 Figure 1 The diagram shows a cross-sectional view of the primary coil during the second assembly step.

[0061] Figure 4 Figure 1 The primary coil shown is a cross-sectional view in the third assembly step.

[0062] Figure 5 Figure 1 The primary coil shown is a cross-sectional view in the fourth assembly step.

[0063] Figure 6 Figure 1 The primary coil shown is a cross-sectional view in the fifth assembly step.

[0064] Figure 7 Figure 1 The primary coil shown is a cross-sectional view in the sixth assembly step.

[0065] Figure 1 shows a cross-sectional view of the primary coil 1 of a non-contact transformer used for an externally excited synchronous motor.

[0066] The primary coil 1 includes a ferrite core 2 and a winding 4. The winding 4 is covered by a tubular insulating layer 5, which is a heat-shrink tubing 9, on the radially inner cylindrical surface and the radially outer cylindrical surface, on the first axial side, and on the second axial side opposite to the first axial side. The winding 4 is disposed in a slotted recess 3 of the ferrite core, which is constructed as a hollow cylinder. The slotted recess 3 is located on the radially outer side of the ferrite core 2. In cross-section, this results in a substantially U-shaped profile.

[0067] Thus, the tubular insulating layer is located on the radial inner cylindrical surface of the winding 4 between it and the groove 3, and further extends on the first and second axial sides of the winding 4 respectively, and is covered by forming the first and second portions 6 and 7 respectively.

[0068] The second portion 7 extends axially along the radial outer cylindrical surface of the winding 4 from the second axial side.

[0069] The first portion 6 of the tubular insulating layer extends axially along the radial outer cylindrical surface of the winding 4, at least in a portion of the first axial side. In this embodiment, the first portion 6 together with the second portion 7 constitutes a double layer of insulation because the second and first portions 7 and 6 overlap each other axially on the radial outer cylindrical surface of the winding 4.

[0070] The winding forms a lead 8 on the first axial side, thereby allowing the winding to be connected to a current or voltage source. The lead 8 extends from the first axial side to the second axial side along the radially outer cylindrical surface. They are axially located between the first portion 6 and the second portion 7 of the tubular insulating layer 5. The lead 8 is guided from the slotted groove 3 to the axial end face of the ferrite core via an axially extending groove 11 on the radially outer side of the ferrite core.

[0071] The winding 4 is configured as a Litz wire 10, particularly a copper Litz wire or an HF-Litz wire made of copper.

[0072] Figures 2 through 7 show... Figure 1 The diagram shows a cross-sectional view of the primary coil at different assembly steps.

[0073] A mounting bushing 12 is arranged on each of the two opposite axial sides of the ferrite core 2. Preferably, the mounting bushing 12 is arranged before the tubular insulating layer 5 is placed on the ferrite core 2. For subsequent assembly steps, it is important that the inner diameter of the mounting bushing 12 is designed to substantially correspond to the outer diameter of the ferrite core 2, but allows the mounting bushing to be pushed axially. In other words, the inner diameter of the mounting bushing 12 has a clearance fit relative to the outer diameter of the ferrite core 2.

[0074] The tubular insulating layer is centrally positioned above the mounting bushing 12 and the ferrite core 2. The tubular insulating layer is chosen such that its inner diameter substantially corresponds to the outer diameter of the mounting bushing, allowing the tubular insulating layer 5 to be positioned above the mounting bushing 12 and the ferrite core 2 and to be axially aligned. The tubular insulating layer 5 extends axially beyond the ferrite core 2 on both sides of the axial direction.

[0075] The hollow cylindrical ferrite core 2 has a slotted groove 3 on its radially outer side for accommodating the winding 4. The mounting bushing 12 covers the ferrite core 2 in axial segments but does not cover the slotted groove area. Initially, the tubular insulating layer is not attached to the ferrite core 2 in the slotted groove 3 area.

[0076] The axial length of the tubular insulating layer is greater than that of the ferrite core 2. For subsequent assembly steps, it is important that the tubular insulating layer 5 is designed such that it has such an axial length that it can be disposed on the mounting bushing at least in a certain section before the mounting bushing 12 is pushed in.

[0077] Figure 3 shows the assembly state where the tubular insulating layer 5 is heat-shrinked onto the ferrite core 2 in the groove region 3. A vacuum is applied to avoid gas entrainment in the groove region 3. Due to heat shrinkage, the axial length of the tubular insulating layer is shortened. The tubular insulating layer is now also attached to the ferrite core in the groove region and covers the ferrite core circumferentially. The tubular insulating layer 5 is also disposed on the mounting bushing at least in a portion of the section.

[0078] Figure 4 shows the assembled state after the winding 4 is applied to the slotted groove 3 region. The winding thus forms a substantially hollow cylindrical shape, having a radially inner cylindrical surface and a radially outer cylindrical surface, a first axial side, and a second axial side opposite to the first axial side. The tubular insulating layer 5 is thus disposed on the radially inner cylindrical surface of the winding, thereby positioned between the winding and the ferrite core. The winding leads 8 extend radially from the first axial side of the slotted groove 3, which corresponds to the first axial side of the winding 4. The tubular insulating layer 5 is disposed between the first axial side of the winding and the first axial side of the slotted groove.

[0079] Figure 5 illustrates the assembly state during the axial pushing of the mounting bushing 12, which is disposed on the second axial side of the ferrite core opposite the first axial side. The mounting bushing 12 pushes the tubular insulating layer 5 axially such that the tubular insulating layer 5 is pushed over the winding 4 from the second axial side of the winding towards the first axial side. In other words, the tubular insulating layer is flipped over the winding to form a second portion 7, which is disposed at least in a portion of the radially outer cylindrical surface of the winding.

[0080] Figure 6 shows Figure 5 The assembly state is as follows: the mounting bushing 12 is pushed in, the tubular insulation layer 5 to be pushed is heat-shrinked onto the winding (4) in the groove 3 area, and the lead wire 8 of the winding 4 is laid onto the area of ​​the pushed tubular insulation layer 5. The mounting bushing 12 used for pushing is removed and is not retained as part of the primary coil. It is particularly preferred that the mounting bushing can be reused.

[0081] Figure 7 illustrates the assembly state during the axial pushing of the mounting bushing 12 disposed on the first axial side. The mounting bushing 12 pushes the tubular insulation layer 5 axially, causing the tubular insulation layer 5 to cover the winding 4 from the first axial side to the second axial side, and at least partially cover the lead wire 8. In other words, the tubular insulation layer is flipped over the winding to form a first portion 6, which is disposed at least partially on the radially outer cylindrical surface of the winding 4, the lead wire 8, and the heat-shrinkable second portion 7.

[0082] In addition to the above, Figure 1 also shows the completion. Figure 7 The mounting bushing 12 is pushed in, and the tubular insulation layer 5 to be pushed in the groove 3 region is heat-shrinked into a heat-shrinked tubular insulation layer, forming an assembly state on the winding 4 and the lead wire 8. The mounting bushing 12 used for pushing is removed and is not retained as part of the primary coil. Particularly preferred is that the mounting bushing can be reused.

[0083] Explanation of reference numerals in the attached figures 1. Primary coil 2 Ferrite core 3. Groove-shaped groove 4 windings 5. Tubular insulation layer 6 Part 1 7 Part Two 8 Lead wires 9. Heat shrink tubing 10 Leeds Line 11 Grooves 12 Install bushings

Claims

1. A primary coil (1) of a non-contact transformer for an externally excited synchronous motor, comprising: A ferrite core (2) is constructed as a hollow cylinder and has a slotted groove (3) on its radial outer side for accommodating the winding (4); A winding (4) is disposed in the groove (3) and has a radial inner cylindrical surface and a radial outer cylindrical surface, a first axial side and a second axial side opposite to the first axial side; A tubular insulating layer (5) is disposed on the radially inner cylindrical surface between the winding (4) and the groove (3), and covers the winding (4) on the first axial side and the second axial side; characterized in that the tubular insulating layer (5) forms a first portion (6) which extends along the radially outer cylindrical surface of the winding (4) at least in a partial axial section from the first axial side; and the tubular insulating layer (5) forms a second portion (7) which extends along the radially outer cylindrical surface of the winding (4) at least in a partial axial section from the second axial side.

2. The primary coil (1) according to claim 1, wherein, The lead wire (8) of the winding (4) extends from the first axial side to the second axial side along the radial outer cylindrical surface; the second portion (7) of the tubular insulating layer (5) is disposed between the winding (4) and the lead wire (8) from the second axial side toward the first axial side; and the first portion (6) of the tubular insulating layer (5) covers the lead wire (8) and the winding (4) at least in a partial section on the radial outer cylindrical surface from the first axial side toward the second axial side.

3. The primary coil (1) according to any one of the preceding claims, wherein, The first portion (6) and the second portion (7) of the tubular insulating layer (5) overlap at least partially along the axial direction on the radial outer cylindrical surface of the winding (4).

4. The primary coil (1) according to any one of the preceding claims, wherein, The tubular insulating layer (5) is composed of a plurality of tubular insulating layers (5), which overlap each other axially on the radial inner cylindrical surface of the winding (4) in the groove (3) region.

5. The primary coil (1) according to any one of the preceding claims, wherein, The tubular insulating layer (5) is a heat shrink tubing (9).

6. The primary coil (1) according to any one of the preceding claims, wherein, The winding (4) is Litz wire (10), especially copper Litz wire.

7. The primary coil (1) according to any one of claims 2 to 5, wherein, The ferrite core (2) has an axially extending groove (11) on its radially outer side for the lead wire (8) of the winding (4) to be axially led out from the groove (3) to the end face.

8. A non-contact transformer for an externally excited synchronous motor, comprising: A primary coil (1) as described in any one of claims 1 to 6; as well as A primary coil, wherein the secondary coil is arranged coaxially with the primary coil (1) and forms a radial air gap.

9. An externally excited synchronous motor, comprising: A non-contact transformer as described in claim 7, or A primary coil (1) as described in any one of claims 1 to 6.

10. A method for manufacturing a primary coil (1) of a non-contact transformer for an externally excited synchronous motor, wherein the primary coil (1) has a tubular insulating layer (5), the method comprising the steps of: a) Provide a hollow cylindrical ferrite core (2) having a slotted groove (3) on the radially outer side for accommodating the winding (4); b) Provide a number of mounting bushings (12) designed as thin-walled hollow cylindrical components, the inner diameter of which is selected to substantially correspond to the outer diameter of the ferrite core (2) and allows the mounting bushings (12) to be axially fitted onto the outer diameter of the ferrite core; c) Provide a tubular insulating layer (5) with an inner diameter such that the tubular insulating layer (5) can be fitted onto the mounting bushing (12) and the ferrite core (2), and the axial length of the tubular insulating layer (5) is greater than the axial length of the ferrite core (2). d) The mounting bushing (12) is placed on the two opposite axial sides of the ferrite core (2), and the tubular insulating layer (5) is positioned so that it extends beyond the ferrite core (2) along the axial direction on both axial sides of the ferrite core (2). e) Apply a winding (4) to the groove (3) region, wherein the lead wire (8) of the winding extends radially on the first axial side of the groove (3) corresponding to the first axial side of the winding; f) Push the mounting bushing (12) located on the second axial side opposite to the first axial side along the axial direction, so that the mounting bushing (12) pushes the tubular insulation layer (5) from the second axial side toward the first axial side onto the winding (4). g) Lay the lead wire (8) of the winding (4) on the area of ​​the pushed tubular insulation layer (5); h) Push the mounting bushing (12) disposed on the first axial side axially so that the mounting bushing (12) pushes the tubular insulation layer (5) over the winding (4) from the first axial side toward the second axial side and at least partially covers the lead wire (8).

11. The method according to claim 10, wherein, The tubular insulating layer (5) is a heat-shrink tubing (9), and the method further includes the following steps: d1) The tubular insulating layer (5) is thermally shrunken onto the ferrite core (2) in the groove (3) region; f1) The tubular insulation layer (5) to be pushed over is thermally shrunk onto the winding (4) in the groove (3) region; h1) The tubular insulation layer (5) to be pushed over is thermally shrunk to the winding (4) and the lead wire (8) in the groove (3) region; and step d1) is performed after step d), step f1) is performed after step f), and step h1) is performed after step h).

12. The method according to claim 11, wherein, The steps d1) and / or f1) and / or h1) are performed under vacuum conditions.

13. The method according to any one of claims 10 to 12, wherein, In step h), the tubular insulation layer (5) is pushed onto at least the radial outer cylindrical surface of the winding (4) to form a partial double layer.

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