HYDROELECTRIC MACHINE SET

MACHINE HYDRO-ELECTRIQUE

English Abstract

ABSTRACT
Hydroelectric machine set, with an electric machine
and a Francis machine, a rotating unit comprising the rotor of the
electric machine and the runner of the Francis machine, and a bearing
arrangement for supporting the rotating unit relatively to the
foundations of the machine set; the rotating unit is supported in
the peripheral region of the supporting ring of the electric machine
and in the peripheral region of the Francis machine runner by means
of a circle of hydrostatic radial bearings.

Claims

WHAT IS CLAIMED IS:
1. Hydroelectric machine set having an electric machine
and a Francis machine; the electric machine having a rotor, and
the Francis machine having a runner; a rotating unit comprising
the rotor of the electric machine and the runner of the Francis
machine; the rotor of the electric machine having a supporting
ring; a bearing arrangement for supporting the rotating unit
relatively to the foundations of the machine set; the improvement
that a first circle of hydrostatic radial bearings supports
the rotating unit in the peripheral region of the supporting
ring of the electric machine rotor, and a second circle of
hydrostatic radial bearings supports the rotating unit in the
peripheral region of the Francis machine runner.
2. Hydroelectric machine set according to claim 1,
wherein a hollow shaft directly connects the peripheral region
of the supporting ring of the electric machine rotor with the
peripheral region of the Francis machine runner.
3. Hydroelectric machine set according to claim 1,
wherein a circle of hydrostatic axial bearings supports the
rotating unit in the peripheral region of the supporting ring
of the rotor and/or in the peripheral region of the runner of the
Francis machine.
4. Hydroelectric machine set according to claim 1,
wherein the rotor is of annular construction.
5. Hydroelectric machine set according to claim 1,
wherein a hydrostatic sealing device bridges the transition region
between the Francis machine runner and the stationary head-
water part and/or tailwater part of the Francis machine.
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Description

3~L
The invention relates to a hydroelectric machine set,
with an electric machine and a Francis rnachine, a rotating unit
comprising the rotor of the electric machine and the runner of the
Francis machine, and a bearing arrangernent for supporting the rotating
unit relatively to the foundations of the machine set.
In known machine sets of this kind the runner of the
Francis machine is connected to the rotor of the electric machine
by a shaft which is mounted by means of hydrodynamic bearings relatively
to the foundations.
The larger the machine set is, the more yieldable it
becomes so that the rotational speeds which are critical for bending
turn out to be lower, or all the material strengths must be considerably
increased. In this way designers very quickly come up against limits
of the si~e of the machine set from the technical and economic
points of view.
The invention has as its object to provide a hydroelectric
machine set 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 more particularly the forces and also the
distances over which the forces have to be transmitted between the
rotor ring of the electric 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 foundat;ons also
increase.
The object is achieved according to the present invention
in a hydroelectric machine set of the type described initially in
that the rotating unit is mounted in the peripheral region of the
supporting ring of the electric machine rotor and in the peripheral
region of the Francis machine runner by means of a circle of hydro-
static radial bearings in each case.

It is particularly advantageous if the peripheral region
of the supporting rung of the rotor is connected directly to the
peripheral region of the Francis machine runner by means of a hollow
shaft.
In order to make it possible to accept the forces due
to weight also over the shortest possible distance in the case oF
machine sets with a vertical axis, the rotating unit is mounted in
the peripheral region of the supporting ring of the electric machine
rotor and/or in the peripheral region of the Francis machine runner
by means of a circle of hydrostatic axial bearings.
Advantageously the rotor of the electric machine is
of annular construction.
It is also advantageous for the hydroelectric machine
set to bridge the transition regions between those walls of the
Francis machine runner which define the working water duct and those
walls of the stationary headwater part and/or tailwater part of the
Francis machine which define the working water duct by means of a
hydrostatic sealing device.
A constructional example of the subject of the invention
is shown in a simplified manner in the drawing by means of which
the invention will be explained in detail.
The single Figure shows a vertical axial section through
a hydroelectric machine set.
The illustrated hydroelectric machine set comprises
an electric machine with a stator 1 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 runner 4. The rotor 2
of the electric machine and the runner 4 of the Francis machine belong
to the rotating unit of the machine set, which is supported by
bearings relatively to a foundation 5.
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The rotating unit 2, 4 is supported in the peripheral
region of the supporting ring 2' of the rotor 2 and in the peripheral
region of the runner 4 by means of in each case a circle of hydro-
static radial bearings 6 and 7 respectively.
The peripheral region of the supporting ring 2'
of the rotor 2 is also connected directly to the peripheral region
of the runner 4 by means of a hollow shaft 8.
In this way those portions of the rotating unit
in which the working 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 constructional example the axial bearing
system of the rotating unit 2, 4 is also arranged in the peripheral
region i.e. in the peripheral region of the supporting ring 2'
of the rotor 2 by a circle of hydrostatic axial bearings 9.
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 runner 4 which forms the upper boundary
of the working water duct extends into the central region of
the rotating unit.
The transition region between the wall 10 of the
runner 4 and that wall 11 of the stationary headwater part
forming the upper boundary to the working water duct, is bridged
by means of a hydrostatic sealing device 12. If necessary, such
hydrostatic sealing devices could also be arranged at the
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transitions 13 and 14 between the external wa'l'l 15 of the
runner 4 and those walls of the stationary headwater part
or tailwater part respectively of the Francis machine which
define the working water duct.
The Francis machine can be operated as a turbine,
as a pump or as a pump turbine.
The peripheral region of the runner 4 also comprises
the annular dics 15, and the peripheral region of the supporting
ring 2' also comprises the region of the end flank of the
1~ supporting ring and the adjacent end portion of the hollow
shaft 8.
The wall forming the hollow shaft 8 can be in the
form of a cylindrical shell or a frustoconical shel'l or can
be composed of cylindrical and frustoconical shell portions.
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