Line sleeve

Abstract

The invention relates to a pump assembly having a pump (1) driven by a wet rotor motor (2), the wet rotor motor (2) being surrounded by a motor housing (3) and having a stator winding (24). The motor housing (3) comprises a bushing assembly (4) for powering a stator winding (24) of the wet rotor motor (2). The bushing assembly (4) has an opening (6) on a portion (5) of the motor housing (3), into which opening a line bushing (7) is arranged in a fastened manner by means of a retaining element (8). The line bushings (7) each have an electrical conductor (9) and an insulating body (10). The electrical conductor (9) and the stator winding (24) have a connection (15), the connection (15) being designed as a crimp connection.

Description

TECHNICAL FIELD

[0001] The invention relates to a pump aggregate with a pump driven by a wet rotor electric machine, wherein the wet rotor electric machine is surrounded by a machine housing and has a stator winding, wherein the machine housing comprises a bushing assembly for supplying the stator winding of the wet rotor electric machine with electrical power, and the bushing assembly has an opening at a portion of the machine housing into which a line bushing (Leitungsdurchführung) is arranged in a fastened manner by means of a holding element each, wherein the line bushing has one conductor and one insulator each. BACKGROUND

[0002] Such a pump aggregate can be used, for example, in the construction of power plants. The housing parts constitute a pressure casing which delimits an interior space relative to the surrounding atmosphere. The pressure casing is mostly designed for very high system pressures.

[0003] An exemplary device is described in EP 1 910 685 B1. The device comprises a pump driven by a liquid-filled electric machine. The electric machine has a housing which is part of a pressure casing.

[0004] Sealless circulating pumps are also called canned circulating pumps and are usually vertical pumps which are driven by a wet rotor electric machine with or without a barrier tube.

[0005] The wet rotor electric machine is mostly an asynchronous squirrel cage electric machine whose rotor and bearings run in the conveying medium. The wet rotor electric machine requires special attention in design, assembly and commissioning so that its machine interior space is reliably filled and vented and solids in the conveying medium are kept away from the liquid-lubricated sliding bearings.

[0006] Here, the pump and the electric machine are located in a common, pressure-resistant housing which has a thermal barrier between the pump and the electric machine part. The thermal barrier can be implemented as an active or passive structural element and allows temperatures of up to 420°C of the conveying medium. The bearings are lubricated by the conveying medium and do not require dynamic seals in addition.

[0007] The wet rotor electric machine is completely filled with liquid. With the rotor and its bearings, the stator and the winding, including the supply line coupling, are also in the liquid. A prerequisite is a water-resistant and pressure-resistant insulation of all live parts. In conventional power plants, the wet rotor electric machine is used as a drive machine for canned circulating pumps.

[0008] In conventional bushing assemblies for supplying the wet rotor electric machine with electrical power, the insulation can be built in two pieces. It consists of an inner insulator and an outer insulator.

[0009] From US 3,043,903 A a bushing assembly is known which has a sole insulator which surrounds the current conductor.

[0010] JP S55 15968 U describes an insulating element which is mounted at a cable and which guides through a cable bushing opening of an electrical device main body. A flange-like protrusion is configured in a section of the insulating element which lies against a shoulder configured in the device main body and is fastened by means of a fixing sleeve.

[0011] In known bushing assemblies, the inner insulator constitutes the pressure-bearing part. The outer insulator is arranged above the inner insulator. Both insulators require a long overlap in the joint action in order to achieve the necessary creepage distance. This increases the installation space. In the case of high loads, metal rings are used for protection. These metal rings require additional sealing points and can heat up due to eddy currents.

[0012] DE 10 2014 209 517 A1 discloses a device with a pump driven by a wet rotor motor. The device has a housing which comprises a bushing assembly for supplying the wet rotor motor with electrical power. The bushing assembly has a line element and an insulator. The bushing assembly comprises a force transmission element.

[0013] For wet rotor motors, in particular under high fluid pressure, a weak point of the line bushing is the sealing against the ambient pressure and the fracture protection in the event of an accident. SUMMARY

[0014] It is the task of the present invention to provide a pump aggregate with a pump and a line bushing which is very compactly constructed. Furthermore, the line bushing should ensure a high level of safety and occupy as little installation space as possible. Here, as few sealing points as possible should be required.

[0015] According to the invention, this task is solved by a pump aggregate with a pump according to the features of claim 1. Preferred variants can be gathered from the main claim, the dependent claims, the description and the figures.

[0016] According to the invention, the electrical conductor has a connection to the stator winding, wherein the connection is configured as a crimp connection.

[0017] A crimp connection is a connection of two components using friction between the two components. Crimp connections belong to the force-fitting connections of the joining technology and are standardized by DIN 8593.

[0018] Preferably, each electrical conductor has a connection to a plastic-insulated conductor wire of the stator winding of the wet rotor motor. In a suitable variant of the invention, the connection is configured as a crimp connection.

[0019] In an advantageous variant of the invention, the electrical conductor has a protrusion which is configured as a hollow cylinder.

[0020] Ideally, the conductor of the stator winding has at least one line end which is introduced into the hollow cylinder. Here, the line end of the plastic-insulated conductor is insulated with a PE insulation up to the section introduced into the hollow cylinder.

[0021] Advantageously, the hollow cylinder of the electrically conductive body has a force-fitting connection with the line end of the conductor of the stator winding.

[0022] In a particularly expedient variant, the connection, in particular the crimp connection, is embodied as a split connection.

[0023] Split is to be understood as a joining method in which two components are connected to one another by plastic deformation, for example by flanging, extruding, crimping or folding. A split connection can only be released conditionally and can only be renewed using suitable tools at the time of repair.

[0024] In the split, a gas-tight connection is formed in the case of correct implementation. By means of the deformation of the split sleeve in the form of the hollow cylinder protrusion of the electrically conductive body and the conductor, a structure is formed which is as oxygen-tight as possible and is thus as protected as possible against corrosion on the inside.

[0025] Ideally, the conductor and the protrusion of the electrically conductive body are constructed from the same material, preferably from copper. Copper is an almost ideal conductor, in particular for use in wet rotor machines. The copper-based split connection achieves an excellent and almost loss-free electrical conductivity.

[0026] Advantageously, the hollow cylinder protrusion of the electrically conductive body is an ideally integrated coupling bolt which is embodied in one piece with the electrically conductive body. Additional components are thus not required, whereby further assembly outlay is saved and line losses due to the use of further components are avoided. The split connection between the conductor and the electrically conductive body is advantageously achieved directly.

[0027] Preferably, the cylinder-shaped connection or winding wire in the form of the conductor is introduced directly into the cylinder-shaped cavity of the protrusion of the electrically conductive body below the bipyramid and is ideally electrically conductively connected force-fittingly.

[0028] Compared to known line sleeves for wet rotor machines, no hard soldering is necessary. An excessively high heat input into the connection is thus avoided, whereby no loading of the electrically conductive connection occurs and no ageing of the insulation occurs. Furthermore, the use of a solder which is not always ideally electrically conductive can be dispensed with.

[0029] In an advantageous variant of the application, the connection comprises at least partially at least four, preferably at least six outer faces, wherein two outer faces are each arranged opposite one another. The split connection deforms the cylinder-shaped protrusion of the electrically conductive body preferably into a hexagonal body, whereby the introduced cylinder-shaped conductor is force-fittingly secured in the protrusion of the electrically conductive body.

[0030] The connecting parts and conductors are preferably covered with shrink tubes up to at least the insulator.

[0031] In an advantageous variation of the invention, the insulator has at least a partially tapered surface that interacts with the conductor.

[0032] A cone is a geometric solid formed when all points of a restricted, continuous planar segment within a plane are connected in straight lines to points outside the plane. In the special case of a circular planar segment, the solid is also called a cone. If the axis is perpendicular to the base, a right circular cone exists.

[0033] Ideally, the conical surface of an insulator is constructed as a portion of a straight circular cone.

[0034] Preferably, the conductor has at least a partially conical surface. In a particularly advantageous variation of the invention, the conical surface of the conductor is constructed as a partial surface of a straight circular cone.

[0035] The conical surfaces of the conductor and the insulator advantageously interact. In a particularly advantageous variant of the invention, the conical surfaces of the conductor and the insulator are configured as corresponding interacting surfaces.

[0036] The conductor preferably comprises a rod-shaped portion and a biconical portion. The conductor is preferably constructed as a slender, preferably cylindrical rod, with a connection portion at its end for attaching to a conductor of the stator winding. Advantageously, a thickened portion in the form of a biconical cone is constructed at the end of the conductor and in front of the connection portion, forming a conical surface of the conductor.

[0037] Ideally, the insulator is configured to contract and fit onto the conductor. Here, the contraction compound extends to the maximum length of the rod-shaped portion of the conductor and transitions to the bicone at the transition section. The tapered surfaces of the insulator and the conductor form a particularly stable end section of the contraction compound. Ideally, the insulator experiences significantly less mechanical load at the bicone due to the contraction fit, thus resulting in a longer service life.

[0038] Furthermore, shrinking the insulator onto the conductor provides advantageous torsional protection, especially compared to adhesive bonding to date.

[0039] Ideally, the tapered surfaces of the insulator and conductor work together. This interaction begins by the insulator contracting and fitting onto the conductor. Additionally, an O-ring, which acts as a seal, is embedded in the conductor at the transition of the tapered surfaces, thus providing redundant protection against fluid leakage should the tapered surfaces of the insulator suffer damage to the connection on the tapered surfaces of the conductor.

[0040] Advantageously, at the end of the electrically conductive body and in front of the connection to the conductor, a thickening in the form of a double cone is configured, which forms a conical face of the electrically conductive body. The double cone achieves an advantageous breaking or puncture protection of the line bushing.

[0041] In a particularly advantageous variant of the application, the insulation body is configured from a high-performance plastic. High-performance plastics are a sub-class of thermoplastics, which are distinguished from engineering plastics and standard plastics, inter alia, by their high-temperature resistance, but also advantageously in terms of chemical resistance and mechanical properties.

[0042] In a particularly advantageous variant of the application, the insulation body is configured from polyether ether ketone (PEEK).

[0043] Polyether ether ketone is a high-temperature-resistant thermoplastic and belongs to the material class of polyaryletherketones. Its melting point is 335°C. PEEK is resistant to almost all organic and inorganic chemicals, high-energy electromagnetic waves, such as gamma rays and X-rays, and also to hydrolysis up to about 280°C. PEEK is preferably used as an insulating material in high-voltage technology due to its good electrical insulation properties and low dielectric loss factor.

[0044] The insulation body preferably has an elongated shape with a cylindrical cavity inside. The electrically conductive body is introduced into the cavity and the insulation body is shrink-fitted onto the electrically conductive body. In the central portion of the insulation body, a thickening is preferably arranged, which is configured as a seat for the line bushing to the opening of the housing. For this purpose, the thickening has a first recess in the direction of the opening of the housing for an O-ring, which takes on the task of sealing the line bushing in the opening of the housing.

[0045] Additionally, the thickening of the insulation body has a further recess in the center of the thickening, into which a further O-ring can be realized for sealing. This second O-ring is advantageously provided as a redundant seal for the line bushing in the opening of the housing. In the event of an unfavorable accident, in which very high pressures and also increased temperatures occur, the further O-ring can maintain the sealing function after the first O-ring has lost its sealing function. For this purpose, the placement of the second O-ring is carried out in such a way that there is no direct contact at first and no large-area contact with hot liquids in the event of damage to the first O-ring.

[0046] Furthermore, the thickening on the side facing away from the O-ring has a seat for a ring configured as a breaking protection. Ideally, this ring can be implemented as a metal ring, wherein the metal material, such as brass or iron, is implemented non-magnetically. In addition, high-temperature-resistant plastics are also suitable. In the event of a so-called breaking, i.e. the insulation body breaks and the electrically conductive body is pressed out of the line bushing, the ring, in combination with the double conical portion of the electrically conductive body for the breaking protection, prevents an actual breaking or puncture and advantageously seals the fluid pressure occurring in the wet rotor machine.

[0047] In a preferred embodiment of the application, the insulator has a metallization.

[0048] To this end, the metallization is preferably embodied in the form of a nickel layer which achieves a reproducible electrical conductivity by a defined layer thickness. The nickel layer is preferably applied in the inner hollow cylinder of the insulator. This is a great improvement in terms of reproducible electrical conductivity, especially with respect to conventionally known, manually applied electrically conductive lacquers.

[0049] The combination of the shrink fit of the insulator and the metallization on the inner side of the insulator achieves a gap-free and air-free contact between the electrical conductor and the insulator. Thus, partial discharges caused by the implementation of the line sleeve are particularly effectively avoided or significantly reduced.

[0050] In contrast to known line sleeves, the line sleeve according to the application does not require a sealing tape, nor does it require an electrically conductive lacquer and likewise no adhesive, whereby an extremely secure connection between the electrical conductor and the insulator can be achieved, which furthermore has improved field control properties.

[0051] Ideally, the line sleeve has a field control lacquer. In a preferred embodiment of the application, the line sleeve has a field control element, whereby the maximum field strength is significantly reduced and at the same time the partial discharge inception voltage can be increased.

[0052] So-called field control comprises all measures which serve to reduce the local electric field strength to such an extent that the electrical strength of the insulating material and the interface is not exceeded at any point.

[0053] For example, the field control lacquer or the field control element has a significantly increased dielectric constant with respect to the insulator, whereby a targeted reduction of the original field strength can be achieved.

[0054] In a preferred embodiment of the application, the line sleeve has a further outer insulator. Preferably, this further outer insulator is positioned over the shrink-fitted insulator and in a non-magnetic threaded bushing in which the line sleeve is fastened in the opening of the housing. Additionally, the outer insulator can be adjusted at the upper end using a fastening element. Preferably, the threaded bushing is embodied as an M64 outer thread.

[0055] In a preferred embodiment of the application, the sleeve assembly comprises three line sleeves. In an alternative embodiment, six line sleeves can also be implemented in the sleeve assembly.

[0056] According to the invention, a pump aggregate with a pump driven by a wet rotor electric machine, wherein the bushing assembly for supplying the wet rotor electric machine with electrical power comprises at least one line bushing with an electric conductor and an insulator, is produced in a method in which the insulator is shrunk onto the electric conductor, and for each line bushing the line end of the stator winding is introduced into the hollow cylinder of the electric conductor, and a form-fit connection is produced by means of a pressing tool.

[0057] According to the invention, a pump aggregate with a pump is used in a power plant circuit with high system pressure for sealing the power supply of the wet rotor electric machine against high system pressure by means of line bushings.

[0058] Further features and advantages of the invention result from the description of the embodiments according to the drawings and from the drawings themselves. BRIEF DESCRIPTION OF DRAWINGS

[0059] Herein: Figure 1 A sectional view of the electric machine pump aggregate is shown; Figure 2 A perspective view of the bushing assembly is shown; Figure 3 A sectional view of the bushing assembly is shown; Figure 4 A sectional view of the line bushing is shown; Figure 5 A detailed view of the line bushing is shown. DETAILED DESCRIPTION

[0060] Figure 1 An electric machine pump aggregate with a wet rotor electric machine 2 is shown. The electric machine housing 3 forms part of a pressure jacket. The interior of the wet rotor electric machine 2 is filled with liquid and has a thermal insulation 25. In order to lead off electrical loss power, a cooling system 17 is present. The wet rotor electric machine 2 comprises two radial bearings 13, 14 and one axial bearing 40.

[0061] The drive force of the wet rotor electric machine 2 acts on the shafting 18 and thus transmits torque to the pump 1. The pump 1 comprises a pump housing 19 in which an impeller 20 and a guide device 21 are arranged. The pump housing 19 is connected to the electric machine housing 3 via at least four tie rods 22.

[0062] The electric machine housing 3 and the pump housing 19 together form a pressure jacket. This pressure jacket is designed for high system pressure.

[0063] The wet rotor electric machine 2 shown in this embodiment is completely filled with liquid. With the rotor 23 and its bearings, the stator winding 24 and the stator winding head 16, including the supply line coupling, are also in the liquid. In order to supply the wet rotor electric machine 2 with power, a bushing assembly 4 is provided in the machine housing 3. For this purpose, a plastic-insulated copper wire 27, which in this embodiment variant has a PE insulation, is coupled from the multi-layer coil of the stator winding 24 to the line bushing 7 by means of a connection 15.

[0064] The bushing assembly 4 comprises a portion 5 formed by a collar-like protrusion. The portion 5 is constructed in one piece with the machine housing 3, whereby it can also withstand high fluid pressures. The portion 5 of the machine housing 3 has openings 6 into which the line bushings 7 are respectively arranged. The number of openings 6 corresponds to the number of line bushings 7 required for the operation of the wet rotor electric machine 2. As can be seen from the perspective view in Fig. 2, the line bushings 7 are arranged in the openings 6 in such a way that they are parallel to one another and to the longitudinal axis of the machine housing 3. Figure 4 As is known, each of the openings 6 has a section 43 with a reduced inner diameter and a section 42 with an increased inner diameter.

[0065] In the bushing assembly 4, a terminal box 28 is arranged into which the line bushings 7 lead. In the terminal box 28, one respective connection pipe 29 is positioned for the mechanical decoupling of a so-called conductive expansion band 30. In this embodiment, the connection pipe 29 is embodied as an epoxy insulation.

[0066] Figure 2 A perspective view of the bushing assembly 4 with three line bushings 7 is shown. In conjunction with the perspective view in Fig. 2, it can be seen that the line bushings 7 are arranged in the openings 6 of the portion 5 of the machine housing 3 in a fixed manner by means of one respective retaining element 8. The outer insulation 26 covers the retaining elements 8. For this purpose, the outer insulation 26 is plugged onto the inner insulation 10 and is fastened in the upper part with a washer 32 and a nut 31. Figure 3 As is known, the line bushings are arranged in the openings 6 of the portion 5 of the machine housing 3 in a fixed manner by means of one respective retaining element 8. The outer insulation 26 covers the retaining elements 8. For this purpose, the outer insulation 26 is plugged onto the inner insulation 10 and is fastened in the upper part with a washer 32 and a nut 31.

[0067] The retaining elements 8 are embodied as non-magnetic threaded bushings, for example with an M64 outer thread. In the embodiment shown, the terminal box 28 is located directly on the collar-like protrusion of the portion 5 of the machine housing 3. The three line bushings 7 lead into the terminal box 28 and have one respective connection to a conductive expansion band 30, which in turn is coupled at one respective connection pipe 29 for mechanical decoupling.

[0068] Figure 4A detailed cross-sectional view of the line bushing 7 is shown. The line bushing 7 comprises an electric conductor 9 which has a rod-shaped portion 11 and a double cone 12. The double cone 12 realizes a conical surface of the electric conductor 9 which is configured as a partial surface of a straight circular cone. The electric conductor 9 is largely configured as an elongated, cylindrical rod, at the end of which (under the reference numeral 44) a not represented connection of the plastic insulated copper wire 27 of the stator winding 24 is arranged. The conical surface of the electric conductor 9 cooperates with a conical surface of the insulator 10 and forms a corresponding active surface pair 41.

[0069] The insulator 10 is composed of polyether ether ketone (PEEK) and is configured to shrink fit onto the electric conductor 9. Here, the shrink fit composite extends at least over half the length of the rod-shaped portion 11 of the electric conductor 9 and passes over into the double cone 12 at the transition. By the shrink fit at the double cone 12, the composite of the insulator 10 and the electric conductor 9 is significantly less subjected to mechanical loads and thus also implemented in long service life in operational use.

[0070] The insulator 10 has a metallization in the form of a substitute nickel layer applied in the inner hollow cylinder of the insulator 10. Thereby a reproducible electrical conductivity is achieved by a defined layer thickness.

[0071] The line bushing 7 has a further outer insulator 26 and is positioned over the shrink fit insulator 10 and within a non-magnetic threaded bushing 8 which fastens the line bushing 7 in the opening 6 of the housing 3. The outer insulator 26 is adjusted at the upper end with a washer 32 and a nut 31. The threaded bushing 8 is implemented with an outer thread. A distance sleeve 46 is configured from PEEK and positions the field control element 45.

[0072] In the central portion of the insulator 10 a thickening 33 is arranged which is configured as a base of the line bushing 7 in the opening 6 of the housing 3. For this purpose, the thickening 33 has a first notch or chamfer 34 in the region of the section 42 of the opening 6 of the housing 3 for realizing a first O-ring 35 which takes over the task of sealing the line bushing 7 in the opening 6 of the housing 3.

[0073] In addition, the thickening 33 of the insulator 10 has a second notch 36 in the center of the thickening 33 in the form of a radially encircling groove into which a second O-ring 37 can be realized for sealing. This second O-ring 37 is advantageously provided as a redundant seal of the line bushing 7 in the opening 6 of the housing 3. In the case of an unfavorable accident (in which very high pressures and also increased temperatures occur), the second O-ring 37 can maintain the sealing action after the loss of the sealing action of the first O-ring 35.

[0074] The thickening 33 has on the side facing away from the first O-ring 35 a seat for a ring 38, which is configured as a rupture protection. The ring 38 is embodied as a metal ring. The metal ring is preferably configured as a brass ring or a ring composed of non-magnetic iron. In the event of a so-called rupture, i.e. the insulation 10 is broken and the conductor 9 is pressed out of the line socket 7, the ring 38, in combination with the double cone 12 of the conductor 9, prevents escape from the insulation 10 for rupture protection.

[0075] Additionally, a third O-ring 39, which seals, is inserted into the conductor 9 at the transition of the conical faces of the insulation 10 and the conductor 9, so that in the event of damage to the conical face of the insulation 10 at the conical face of the conductor 9, there is a redundant protection against escape of fluid.

[0076] Figure 5 A detailed view of the line socket 7, in particular of the connection 15, which is embodied as a crimp connection or a split connection, is shown. The conductor 9 has a protrusion configured as a hollow cylinder 47. The cylindrical wire end 18 of the conductor wire 27 is introduced into the hollow cylinder 47 and is joined to the force-fitting connection 15 with a pressing tool.

[0077] The conductor wire 27, including the cylindrical wire end 18 and the protrusion of the conductor 9, is configured from copper. The copper-based crimp connection achieves an excellent and virtually loss-free electrical conductivity.

Claims

1. A pump unit comprising a pump (1) driven by a wet rotor motor (2), - in, The wet rotor motor (2) is surrounded by a motor housing (3) and has stator windings (24). - The motor housing (3) includes a bushing assembly (4) for supplying power to the stator windings (24) of the wet rotor motor (2), and the bushing assembly (4) has an opening (6) at a portion (5) of the motor housing (3), into which line bushings (7) are respectively fastened by means of retaining elements (8). - The line bushing (7) has a conductor (9) and an insulator (10). The feature is that the conductor (9) and the stator winding (24) have a connecting portion (15), wherein the connecting portion (15) is configured as a press-fit connection portion.

2. The pump unit according to claim 1, characterized in that, The conductor (9) has a protrusion constructed as a hollow cylinder (47).

3. The pump unit according to claim 1 or 2, characterized in that, The stator winding (24) has at least one wire end (18) introduced into the hollow cylinder (47).

4. The pump unit according to claim 2 or 3, characterized in that, The hollow column (47) and the wire end (18) have a force-fitting connecting part (15).

5. The pump unit according to any one of claims 1 to 4, characterized in that, The connecting portion (15) includes at least four, preferably at least six, outer surfaces, wherein two outer surfaces are arranged opposite to each other.

6. The pump unit according to any one of claims 1 to 5, characterized in that, The insulator (10) has at least a partially tapered surface that interacts with the conductor (9).

7. The pump unit according to any one of claims 1 to 6, characterized in that, The conductor (9) has at least a partially conical surface.

8. The pump unit according to any one of claims 1 to 7, characterized in that, The conductor (9) includes a rod-shaped portion (11) and a portion in the form of a double cone (12).

9. The pump unit according to any one of claims 1 to 8, characterized in that, The insulator (10) is configured to shrink and fit onto the conductor (9).

10. The pump unit according to any one of claims 1 to 9, characterized in that, The insulator (10) is constructed of high-performance plastic.

11. The pump unit according to any one of claims 1 to 10, characterized in that, The insulator (10) has a metallized portion.

12. The pump unit according to any one of claims 1 to 11, characterized in that, The line bushing (7) has a field control element (45).

13. A method for manufacturing a pump unit, the pump unit having a pump (1) driven by a wet rotor motor (2), wherein, The bushing assembly (4) for supplying power to the wet rotor motor (2) includes a line bushing (7) having a conductor (9) and an insulator (10), characterized in that, for each line bushing (7), the wire end (18) of the stator winding (24) is introduced into the hollow column (47) of the conductor (9), and a form-fitting connection (15) is generated by means of a pressing tool.

14. Use of a pump unit with a pump (1) in a power plant circuit with high system pressure, for sealing the power supply of the wet rotor motor (2) with a bushing (7) to prevent high system pressure.

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