Note: Descriptions are shown in the official language in which they were submitted.
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ECCENTRICALLY MOUNTED WATER TURBINE WITH GUIDED BLADES
FIELD OF THE INVENTION
[0001] The present invention relates to an improvement in low head water
turbines, and more particularly to turbines which can capture energy from
heads
of water from about six meters, down to about one meter, for use, for example,
in
generating electricity.
BACKGROUND OF THE INVENTION
[0002] Traditionally, low head water turbines have been of an open type, as
exemplified for example by conventional water wheels, and have had extremely
low efficiency. This has meant, for example, that sections of small rivers
having a
low head or drop, have been unsuitable for generation of hydro electric power.
Conventional power generation turbines such as Francis turbines, Kaplan
turbines
and Peleton turbines traditionally require high heads of water to generate the
water pressure and velocity required to move the turbine blades. Such
arrangements have necessitated large dams, construction of flumes and the
like,
necessitating, often, massive capital expenditure.
[0003] The present invention is intended to provide a more efficient
construction of turbine which can be economically constructed, and is suitable
for
low head electric power generation applications.
SUMMARY OF THE INVENTION
[0004] In accordance with the present invention there is provided a low
head water turbine comprising a runner having a cylindrical outer surface
extending between opposite ends and a shaft centrally positioned in the runner
along a horizontal axis of rotation. A plurality of similar blades having
inner and
outer edges and sides extending between the inner and outer edges are evenly
spaced about the surface of the runner and extend to the ends of the runner.
The
blades are similarly pivotably secured along their inner edges to the outer
surface
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of the runner so as to pivot in the direction of rotation of the runner
between a
closed position lying adjacent the outer surface of the runner and an open
position
at an angle thereto. The turbine further comprises a housing having end walls
and a cylindrical side wall extending therebetween. The housing completely
encases the runner and its blades. The end walls of the housing are proximal
to
the ends of the runner. The shaft of the runner is eccentrically mounted
within
the housing on the end walls of the housing for rotation of the runner about
the
horizontal axis of rotation so that the cylindrical outer surface of the
runner is
spaced closer to an upper portion of the cylindrical side wall of the housing
and
farther from a lower portion thereof. At least one curved endless groove is
provided in at least one of the end walls of the housing. The curved endless
groove circumscribes the shaft and is spaced from the cylindrical side wall of
the
housing by a fixed distance about the curved endless groove. A connector
extends from a corresponding side of each of the blades and is seated in the
curved endless groove for travel therein as the runner rotates. A water inlet
opening is located in a lower, forward portion of the housing and below the
axis of
rotation of the runner. A water outlet opening is located in a lower, rearward
portion of the housing. The blades and connectors are constructed and
positioned
and the curved endless groove is of a circumference, so that, during operation
of
the turbine, as the connectors travel in the curved endless groove, they draw
the
blades to the closed position as the blades approach and pass the upper
portion of
the cylindrical side wall of the housing, and extend the blades to the open
position
as the blades move below the horizontal axis of rotation to the lower
position, all
the time the outer edges of the blades being adjacent to the cylindrical side
wall of
the housing so as to restrict the passage of water between the outer edges of
the
blades and the cylindrical side wall of the housing.
[0005] The turbine of the present invention, in tests, has proven to operate
at an efficiency which is far higher than conventional low head water
turbines.
Unlike conventional low head turbines which must be constructed on a site-
specific
basis, the turbine of the present invention may be made in modular form to a
uniform design and size. A plurality of similar turbines may be placed in a
stream
in series or parallel fashion to generate additional power.
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[0006] In this specification, the term cylindrical encompasses at least
circular cylindrical and ellipsoid cylindrical shapes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] These and other objects and advantages of the invention will become
apparent upon reading the following detailed description and upon referring to
the
drawings in which:
[0008] FIGURE 1 is partially exploded perspective view of a part of an
embodiment of the invention;
[0009] FIGURE 2 is a side section view of the embodiment of Figure 1 along
the line 2-2; and
[0010] FIGURE 3 is a side section view of a part of an alternative
embodiment of the invention;
[0011] While the invention will be described in conjunction with its
illustrated
embodiments, it will be understood that it is not intended to limit the
invention to
such embodiments. On the contrary, it is intended to cover all alternatives,
modifications and equivalents as may be included within the spirit and scope
of
the invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012] In the following description, similar features in the drawings have
been given similar reference numerals.
[0013] Figure 1 illustrates a low head water turbine 10 in accordance with
the invention comprising a runner 12 having a cylindrical outer surface 14
extending between opposite ends 16. A shaft 18 is centrally positioned in the
runner 12 along a horizontal axis of rotation 20. A plurality of similar
blades 22
are evenly spaced about the cylindrical outer surface 14 of the runner 12. The
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blades 22 have inner edges 24, outer edges 26 and sides 28 extending between
the inner edges 24 and the outer edges 26. Sides 28 are coextensive with the
ends 16 of the runner 12. The blades 22 are similarly pivotably secured along
their inner edges 24 to the cylindrical outer surface 14 of the runner 12 so
as to
pivot in the direction of rotation of the runner 12 between a closed position
lying
adjacent the cylindrical outer surface 14 of the runner 12 and an open
position at
an angle thereto.
[0014] A housing 32 having end walls 34 and a cylindrical side wall 36
extending therebetween completely encases the runner 12 and its blades 22. The
end walls 34 are proximal to the ends 16 of the runner 12. The shaft 18 of the
runner 12 is eccentrically mounted within the housing 32 on the end walls 34
of
the housing 32 for rotation of the runner 12 about the horizontal axis of
rotation
20 so that the cylindrical outer surface 14 of the runner 12 is spaced closer
to an
upper portion 38 of the cylindrical side wall 36 of the housing 32 and farther
from
a lower portion 40 thereof. The shaft 18 is cylindrical and is mounted in
corresponding circular slots 42 in the end walls 34 of the housing 32.
[0015] A curved endless groove 46 is provided in one of the end walls 34 of
the housing 32. Alternatively, a curved endless groove 46 may be provided in
both of the end walls 34 of the housing 32 adjacent to corresponding ends of
the
cylindrical side wall 36 of the housing 32 (as shown in Figure 1). The curved
endless groove 46 has a center coincident with a central axis of the
cylindrical side
wall 36 of the housing 32 and is spaced from said cylindrical side wall 36 of
the
housing 32 by a fixed distance about the curved endless groove 46.
[0016] A connector 52 extends from a corresponding side 28 of each of the
blades 22 and is seated in the curved endless groove 46 in one of the end
walls 34
of the housing 32 for travel therein as the runner 12 rotates. Optionally, a
second
endless groove 46 may be provided in the other end wall 34 of the housing with
connectors 52 extending from the other side 28 of each blade 22. The
connectors
52 may be lugs, wheels (e.g. roller bearing mounted wheels), bearings or any
other suitable part for sliding movement in the curved endless groove 46. The
shape of the connector 52 may be constrained so as to be seated in the curved
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endless groove 46. Each connector 52 may extend from a portion of the side 28
of the corresponding blade 22 which is proximal to the outer edge 26 of the
blade
22. Of course, it should be understood that the connectors 52 may extend from
anywhere along the corresponding sides 28. The leverage provided by the
connectors 52 will of course be greater where the connectors 52 are positioned
proximal to the outer edges 26.
[0017] Similarly, a lateral cross section of the curved endless groove 46 may
be rectilinear, curved or any other suitable shape and/or may comprise a rail
for
receiving a wheel. The groove 46 may be of such a width that the connector
fits
tightly or loosely in the groove 46. The connector may engage an inner side,
an
outer side, or both sides of the groove 46.
[0018] The friction force between the connector 52 and the groove 46 may
be controlled using known methods and parts. Similarly, at sites where silt
contamination and the like is a concern, a suitable choice of connector and
groove
configuration may be made.
[0019] The blades 22 are constructed and positioned and the curved endless
groove 46 is of a circumference, so that, during operation of the turbine 10,
as
the connectors 52 travel in the curved endless groove 46, they draw the blades
22
to the closed position as the blades 22 approach and pass the upper portion 38
of
the cylindrical side wall 36 of the housing 32, and extend the blades 22 to
the
open position as the blades 22 move below the horizontal axis of rotation 20
to
the lower position, all the time the outer edges 26 of the blades 22 being
adjacent
the cylindrical side wall 36 of the housing 32. The transition of between the
open
and closed positions of the blades 22 is smooth because of the cooperation of
the
connectors 52 and the curved endless groove 46.
[0020] Figure 2 illustrates turbine 10 in whicii a flow of water is brought to
an inlet opening 54 of the turbine 10 by way of a pipe 80. The inlet opening
54 is
located in a lower, forward portion 56 of the housing 32 and below the
horizontal
axis of rotation 20 of the runner 12. An outlet opening 58 is located in a
lower,
rearward portion 60 of the housing 32.
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[0021] The inlet opening 54 may be formed by series of spaced slots 62 in
the wall of the housing 32. The total area of the spaced slots 62 may
progressively increase from top to bottom of the inlet opening 54 so as to
permit
progressively greater inflow of water from top to bottom of the inlet opening
54.
The outlet opening 58 may be similarly formed by a series of spaced slots 64
in
the wall of the housing 32. The inlet and outlet openings 54 and 58 may act as
gratings which can support the outer edges 26 of the blades 22. An additional
grating such as a coarse grade screen (not shown) may be installed upstream of
the inlet opening 54 to prevent debris from entering the housing 32 of the
turbine
10.
[0022] Water will enter via inlet opening 54 and will flow against blades 22
in the lower, forward (upstream) portion 56 of the housing 32. Runner 12 thus
rotates about the horizontal axis of rotation 20 in a clockwise motion.
[0023] Most of the water flowing into the housing 32 is able to effectively
and efficiently bear against blades 22 in their open position to cause
rotation of
the runner 12 because the flow of water into housing 32 through inlet opening
54
is directed at the blades 22 in the lower, forward portion 56 of the housing
32
(where the blades 22 are in the open position). In addition, there is little
opportunity for water to escape between the sides 28 of the blades 22 and the
end walls 34 of the housing 32, and between the outer edges 26 of the blades
22
and the corresponding inner surface of the cylindrical side wall 36 of the
housing
32. It is essentially the eccentric mounting of runner 12 within housing 32,
and
the smooth transition of the blades 22 between the open and closed positions,
permitted by the eccentric mounting of runner 12 and the positioning of the
blades 22 by the travel of the connectors 52 in the curved endless groove 46,
which leads to the increased efficiency of operation of the turbine 10.
[0024] The blades 22 may be curved along a transverse axis as illustrated
so as to conform to the cylindrical outer surface 14 of the runner 12 when in
the
closed position.
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[0025] The inner surfaces 66 of the blades 22 may each be provided with
one or more blade spacer plates (not shown) which, when in the closed
position,
lie in registry with one more runner spacer plates 72 on the cylindrical outer
surface 14 of the runner 12. The outer surfaces 68 of the blades 22 thus form
a
streamlined outer surface. Additional plates 70 may be provided between the
runner spacer plates 72 and the cylindrical outer surface 14 of the runner 12.
[0026] Elongated flexible strips 78 are secured to the outer edges 26 of the
blades 22. During operation of the turbine 10, these elongated flexible strips
78
reduce passage of water between the outer edges 26 of the blades 22 and the
cylindrical side wall 36 of the housing 32. The elongated flexible strips 78
are
made of a low friction plastic.
[0027] In Figures 1 and 2, the cylindrical side wall 36 of the housing 32 is
circular in lateral cross-section. The curved endless groove 46 is therefore
also
circular in lateral cross-section. Alternatively, as shown in Figure 3, the
cylindrical
side wall 36 of the housing 32 may be elliptical in lateral cross-section.
Where the
cylindrical side wall 36 is elliptical in lateral cross-section, the curved
endless
groove 46 would also be elliptical in lateral cross-section and corresponding
portions of groove 46 would be positioned a sirnilar distance from side wall
36.
[0028] The turbine 10 is scalable in size and any suitable number of blades
22 may be used. For example, eight blades 22 are shown in the Figures. The
number of blades may depend upon the size of the turbine 10 and
characteristics
of the turbine site (e.g. velocity of water flow).
[0029] A plurality of turbines 10 as described may be placed in a waterway
in either downstream (series) or side-by-side (parallel) arrangement. The
series
and parallel arrangements are suitable for different applications and provide
different advantages, depending upon the characteristics of a particular
turbine
site.
[0030] Conventional means of converting the mechanical energy from the
rotation of the runner 12 to electrical energy may be combined with the
turbine
for production of electricity.
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[0031] Thus, it is apparent that there has been provided in accordance with
the invention a low head water turbine that fully satisfies the objects, aims
and
advantages set forth above. While the invention has been described in
conjunction with illustrated embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to those skilled
in the
art in light of the foregoing description. Accordingly, it is intended to
embrace all
such alternatives, modifications and variations as fall within the spirit and
broad
scope of the invention.
