GB1603995A

GB1603995A - Hydroelectric machine set

Info

Publication number: GB1603995A
Application number: GB20165/78A
Authority: GB
Original assignee: Escher Wyss AG
Current assignee: Sulzer Escher Wyss AG
Priority date: 1977-05-25
Filing date: 1978-05-17
Publication date: 1981-12-02
Also published as: SE7805952L; BE867317A; FR2392246A1; DE2821458A1; FI60596C; JPS53146048A; DE2821458C2; BR7803209A; IT1094732B; FI60596B; YU123478A; PT68064A; AT359004B; CH621602A5; AR215057A1; FR2392246B1; PT68064B; IT7822758A0; AU3641678A; FI781646A

Abstract

The generating set has an electrical machine with a rotor (2) and a Francis water turbine. It has a rotating unit, which is essentially formed by the rotor (2) of the electrical machine and the wheel (4) of the Francis water turbine. This rotating unit (2, 8, 4) is supported both in the circumferential area of the rotor (2) or its retaining ring (2') and in the circumferential area of the wheel (4), in each case by means of a ring of hydrostatic radial bearings (6, 7). Due to the fact that the rotating unit is supported where the greatest masses are located and where the operating forces occur, stable operation of the generating set is possible even where this is of large dimensions. <IMAGE>

Description

(54) HYDROELECTRIC MACHINE SET (71) We, ESCHER WYSS LIMITED, a Swiss Company, of Hardstrasse 319, 8023 Zurich, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a hydroelectric machine set and in particular to a machine set of the type comprising an electric machine and a "Francis" machine, the machine set including a rotating unit comprising the rotor of the electric machine and the rotor of the Francis machine, and a bearing arrangement for supporting the rotating unit relatively to the foundations of the machine.

In known machines of this type the rotor of the Francis machine is connected to the rotor of the electric machine by a shaft which is mounted on the foundations by means of hydrodynamic bearings.

The larger the machine set, the more yieldable it becomes so that the rotational speeds which are critical for bending turn out to be lower. Equally the material strengths must be considerably increased. In this way designers very quickly come up against technical and economic limits on the size of the machine.

The invention has as its general aim to provide a hydroelectric machine set of the above type which is of substantially more stable construction, so that larger unit power outputs can be obtained.

The invention is based on the realisation that as the machine set becomes larger, the forces and also the distances over which the forces have to be transmitted between the ring of poles of the electrical machine, the supported shaft and the ring of blades of the Francis machine also increase, and that the forces and distances between the bearings and the foundations also increase.

According to the invention, an hydroelectric machine set comprises an electric machine and a Francis machine, the rotors of which are coupled for rotation as a single unit; a supporting ring for the rotor of the electric machine; and two axially spaced rings of hydrostatic bearings for supporting the unit which bear radially on the unit to respectively support the supporting ring of the electric machine rotor at one end of the unit and the Francis machine rotor at the other end of the unit. The unit is thus supported near those portions of it in which the operating forces occur. The rotors are preferably coupled through a hollow shaft, one of the rings of bearings being located against the shaft adjacent the electric machine rotor. Conveniently, the electric machine rotor is of annular construction.

In preferred embodiments of the invention, the machine set includes a ring of hydrostatic bearings acting on the single unit to support same in the axial direction.

Typically, the axially acting bearings act on the periphery of the electric machine rotor supporting ring.

It is also advantageous for the transition regions between those walls of the electric machine rotor which define the service water chamber and those walls of the stationary headwater part and/or tailwater part of the Francis machine which define the service water chamber to be sealed by means of a hydrostatic sealing device.

The invention will now be described by way of example and with reference to the accompanying drawing which is a vertical axial section through a hydroelectric machine set in accordance with an embodiment thereof.

The hydroelectric machine set shown in the drawing comprises an electric machine with a stator I and a rotor 2 with a supporting ring 2' for the poles or the winding, and also a Francis machine with a stationary ring of guide blades 3 and a rotor 4. The rotor 2 of the electric machine and the rotor 4 of the Francis machine belong to the rotating unit of the machine set, which is supported by bearings relatively to a foundation 5.

The rotating unit 2, 4 is supported both adjacent the supporting ring 2' of the rotor and at the rotor 4 respectively by means of rings 6, 7 of hydrostatic radial bearings.

The supporting ring 2' of the rotor 2 is connected directly to the rotor 4 by means of a hollow shaft 8.

In this way those portions of the rotating unit in which the operating forces occur, are connected to one another over the shortest distances and supported in the foundation without using any circuitous routes. This means that the machine set is very stable and yet is of light weight, which makes it possible to construct relatively large units. Since the bearings of the rotating unit are constructed as hydrostatic bearings, the frictional forces remain small in spite of the relatively large bearing diameters.

In the illustrated example the rotating unit is also supported in the axial direction by means of a ring 9 of hydrostatic axial bearings 9 acting on the supporting ring 2' of the electric machine rotor 2.

The rotor 2 of the electric machine has a large central aperture i.e., it is annular in construction, so that only that wall 10 of the rotor 4 which forms the upper boundary of the service water chamber extends into the central region of the rotating unit.

The transition region between the wall 10 of the rotor 4 and that wall 11 of the stationary headwater part forming the upper boundary to the service water chamber, that is to say the ring of guide blades 3, is bridged by means of a hydrostatic sealing device 12.

If necessary, such hydrostatic sealing devices could also be arranged at the transitions 13 and 14 between the external wall 15 of the rotor 4 and those walls of the stationary headwater part or tailwater part respectively of the Francis machine which define the service water chamber.

The Francis machine can be operated as a turbine, with the electric machine being a generator; as a pump with the electric machine being a motor, or as a pump turbine.

The hollow shaft 8 can be in the form of a cylindrical shell or a frustoconical shell or can be composed of cylindrical and frustoconical shell portions.

WHAT WE CLAIM IS: 1. An hydroelectric machine set comprising an electric machine and a Francis machine, the rotors of which are coupled for rotation as a single unit; a supporting ring for the rotor of the electric machine; and two axially spaced rings of hydrostatic bearings for supporting the unit which bear radially on the unit to respectively support the supporting ring of the electric machine rotor at one end of the unit and the Francis machine rotor at the other end of the unit.

2. A machine set according to Claim 1 wherein the rotors are coupled through a hollow shaft, one of the rings of bearings being located against the shaft adjacent the electrical machine rotor.

3. A machine set according to Claim 1 or Claim 2 including a ring of hydrostatic bearings acting on the single unit to support same in the axial direction.

4. A machine set according to Claim 3 wherein the axially acting bearings act on the supporting ring of the electrical machine rotor supporting ring.

5. A machine set according to any preceding Claim including an hydrostatic sealing device between a stationary wall of the machine set defining the water flow path to or from the Francis machine rotor and a contiguous wall of the Francis machine rotor.

6. A machine set according to any preceding Claim wherein the Francis machine is a turbine and the electrical machine is a generator.

7. An hydroelectric machine set substantially as described herein with reference to and as illustrated by the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. 4. The rotor 2 of the electric machine and the rotor 4 of the Francis machine belong to the rotating unit of the machine set, which is supported by bearings relatively to a foundation 5. The rotating unit 2, 4 is supported both adjacent the supporting ring 2' of the rotor and at the rotor 4 respectively by means of rings 6, 7 of hydrostatic radial bearings. The supporting ring 2' of the rotor 2 is connected directly to the rotor 4 by means of a hollow shaft 8. In this way those portions of the rotating unit in which the operating forces occur, are connected to one another over the shortest distances and supported in the foundation without using any circuitous routes. This means that the machine set is very stable and yet is of light weight, which makes it possible to construct relatively large units. Since the bearings of the rotating unit are constructed as hydrostatic bearings, the frictional forces remain small in spite of the relatively large bearing diameters. In the illustrated example the rotating unit is also supported in the axial direction by means of a ring 9 of hydrostatic axial bearings 9 acting on the supporting ring 2' of the electric machine rotor 2. The rotor 2 of the electric machine has a large central aperture i.e., it is annular in construction, so that only that wall 10 of the rotor 4 which forms the upper boundary of the service water chamber extends into the central region of the rotating unit. The transition region between the wall 10 of the rotor 4 and that wall 11 of the stationary headwater part forming the upper boundary to the service water chamber, that is to say the ring of guide blades 3, is bridged by means of a hydrostatic sealing device 12. If necessary, such hydrostatic sealing devices could also be arranged at the transitions 13 and 14 between the external wall 15 of the rotor 4 and those walls of the stationary headwater part or tailwater part respectively of the Francis machine which define the service water chamber. The Francis machine can be operated as a turbine, with the electric machine being a generator; as a pump with the electric machine being a motor, or as a pump turbine. The hollow shaft 8 can be in the form of a cylindrical shell or a frustoconical shell or can be composed of cylindrical and frustoconical shell portions. WHAT WE CLAIM IS:

1. An hydroelectric machine set comprising an electric machine and a Francis machine, the rotors of which are coupled for rotation as a single unit; a supporting ring for the rotor of the electric machine; and two axially spaced rings of hydrostatic bearings for supporting the unit which bear radially on the unit to respectively support the supporting ring of the electric machine rotor at one end of the unit and the Francis machine rotor at the other end of the unit.