The invention relates to an electric generator as stated in the introductory part of claim 1, for use with a water turbine. It also relates to a turbine generator assembly, with a turbine integrated with such an electric generator.

Background Water turbines and electric generators to be operated together are usually built as separate units in different places, and are assembled with a shaft connection, a gear or a belt drive. This design requires much space and it is not efficient from a manufacturing point of view. Additionally, the generator will need particular cooling and each unit needs a complete journaling. A separated design like this will need an enclosure, normally in the form of a housing, which will increase the costs for smaller plants.

Turbines having a vertical shaft, where the generator is arranged directly on the turbine, are previously known, but this arrangement is restricted to certain types of turbines.

Also known are tubular turbines which are integrated with a generator surrounding the turbine blades, and are directly connected to them. This scheme is restricted to certain types and sizes of turbines.

A further drawback to prior art turbine generator assemblies is the relatively small bearings, which means increased wear and maintenance. Conventional power plants tend to have bearings due for replacement at certain intervals.

Object The main object of the invention is to create an electric generator, improved in respect to expenses and service life compared to known generators. It is a particular object to create an electric generator which can be better integrated with a water turbine than prior art generators, and to reduce the construction costs. It is particularly an object to increase the service life of the bearings compared to prior art generators, to reduce the need for maintenance and repair. It is also an object to improve the cooling of the parts of the generator in which heat is generated. The generator should be flexible in regard to assembly with different kinds of turbines.

It is also an object to create an integrated turbine generator assembly which can be manufactured more efficiently, and which has a longer service life for bearings and better cooling of heated parts, than prior art turbine generator assemblies.

The Invention The invention is stated in claim 1. With this electrical generator, the objects of the invention are achieved.

With this scheme the generator can be submerged in the flow of water powering the turbine and be cooled by this flow. It is also possible to create bearings having the rotating parts lubricated and cooled by the flow of water.

Further favourable features of the invention will appear from the remaining claims.

Example The invention will be described in more detail in the following, with reference to the drawings, in which Figure 1 shows a partly sectioned perspective view of a tubular turbine assembly with an integrated turbine and electric generator according to the invention, Figure 2 shows an axial section through the turbine assembly of Figure 1, Figure 3 shows an end view from above in Figure 2, Figure 4 shows a perspective view of a further embodiment of an electric generator according to the invention, with a turbine arranged at the upper end of the generator, while Figure 5 shows an axial section through a part of an electrical generator of Figure 4.

In Figure 1 , a tubular turbine assembly with an integrated water turbine and an electrical generator is shown, which is assembled of the following main parts: - a centrally located generator unit 11, - a turbine unit 12 with blades 13 protruding radially from the generator unit 11, - three tubular sections surround the generator turbine assembly 11, 12, an upstream tubular section 14, with end flanges 15, 16, a central tubular section 17 with end flanges 18, 19 and a downstream tubular section 20 with end flanges 21, 22, said tubular sections being joined by bolting the flanges together longitudinally.

The upstream part of the generator turbine assembly 11, 12 is covered by a spherical dome 23 with six radial wings 24 supported on the inside of the tubular section 14.

Figures 2 and 3 show further details of the tubular turbine assembly of Figure 1. At least one of the wings 24 is hollow, with an opening 25 through the wall of the upstream tubular section 14, and a corresponding opening 26 through the spherical dome 23, into an inner void 27 in this dome. This void may be dry or filled with oil. These openings provide the access for energy cables and signal connections to the inner part of the electric generator.

The assembly of the spherical dome 23, the carrying tube 35, and the outlet 30 of the stator, provides the support structure of the generator for j ournaling and the transfer of torque .

The journaling of the generator turbine assembly 11, 12 in the example, is provided for a vertical axis of rotation. The journaling includes a lower thrust bearing 28 and an upper radial slide bearing 29. This assembly can also be mounted with an axis orientation different from the aforementioned orientation.

As an alternative to the slide bearing 28 and 29, magnetic bearings or other suitable bearings, being lubricated and cooled by a water flow, can be used.

Downstream, under the generator turbine assembly 11, 12, a conical guiding body 30 is arranged to reduce turbulence of the exiting water.

The generator 11 includes an annular ring of permanent magnets 31 being secured to a tubular magnetic yoke 32, which carries external turbine blades 13, and which can be integrated therewith. The permanent magnets 31 rotate, in the example, around a tube 40 of composite material which is enclosing a stator 33 with magnetic windings 34. The stator 33 is carried by a tube 35 extending between an upper end shield 36 and a lower end shield 37. The carrying tube 35 of the stator telescopically engages with O-rings a water inlet tube 38 extending from the end of the spherical dome 23 through the upper end shield 36. Correspondingly the lower end shield 37, being bolted to an inner end flange 38 on the stator tube 35 has an outlet opening 39. Thus water can flow through the inside of stator 33 for cooling it. The water, when leaving the carrying tube 35 of the stator, provides a hydraulic/balance of the axial forces.

Figures 4 and 5 show an embodiment of the invention wherein the generator unit and the turbine unit are arranged axially apart, but with the water flow conduit integrated. This embodiment includes a turbine wheel 41 of the Pelton type, which can also be of the Francis type. The turbine wheel 41 is integrated with an axial tube 42 extending down to and carrying a rotor 41 of an electric generator 44. The rotor 43 includes a central tube 45 attached to the axial tube 42, having an annular series of permanent magnets 46 externally attached. The permanent magnets 46 are surrounded by a stator 47 with coils 48. At the lower end, the rotor 43 is carried by a thrust slide bearing 49 which is supplied with water through the tube 42 and the stator tube 45 of the rotor. The stator 47 is surrounded by a closed shield 50 with a cable manifold 51 and a radial tube 52 for electrical cables. This arrangement is enclosed by a closed cylindrical housing 53.

The supply of water to the turbine wheel 41 is through an annular manifold 54 arranged over the housing 53, with four valves 55 and four pipes 56, each extending toward a nozzle 57 at the turbine wheel 41. Each nozzle 57 has a control arrangement accessible through a tube 58, extending through the wall of the housing 53.

The water exits the housing 53 through two axial outlet pipes 59, 60 arranged at the bottom of the housing 53.

At the upper part of the rotor 43, a radial bearing 61 is arranged. The tubular manifold 51 has a connecting stud 62, with an external end flange 63, for connecting the assembly to a down pipe. The housing 53 has a lid with an annular outer part 64, and a central, removable part 65 (Figure 5). Modifications The embodiments shown in the examples can be modified in various ways. E. g. multiple contra rotating turbine wheels can be arranged successively on the embodiment of Figures 1 - 3, each having its generator part. The bearings can be provided according to the prior art, to utilize water lubrication and water cooling.