Note: Descriptions are shown in the official language in which they were submitted.
CA 02678384 2009-09-09
Title of the invention: Tideway anchor
Background of the invention
The lateral force of tidal flow on objects positioned on the sea bed is
considerable,
especially if it is equipment for extracting energy from the tide. The
following
improvement is particularly designed for use with my tidal energy invention,
disclosed in W02007086037, but of course has other applications also. It uses
a plug
and socket type of anchoring, as can be found in the disclosure of EP0045613
(Al).
The latter disclosure is for semi-permanent anchoring, but for use with
equipment for
tidal energy, it is necessary for the plug to which the equipment is attached
to be able
to be withdrawn at fairly frequent intervals from its socket for maintenance
of the
equipment.
Brief summary of the invention
If friction alone is relied upon to keep both components of the anchor
together when
the tidal force is acting to separate them, the socket in the sea bed needs to
be deep.
This depth can be greatly decreased if plug and socket are positively locked
together
when the tide is flowing. This of course has to be combined with absolutely
reliable
means of unlocking them during the tidal null period, so that the plug and
whatever is
attached to it can be removed for maintenance purposes at that time. This
invention
achieves both these objectives through a locking mechanism which is actuated
by
reversal in the direction of the tidal flow.
Description of the drawing
The Figure is a section of an embodiment of the invention.
Detailed description of the invention
In the Figure, 1 is a plug to which whatever is desired to be anchored in the
tidal
stream is attached, and 2 is a socket in the sea bed into which plug 1 fits. 7
is a shaft
which pivots on axle 8, journalled in trunnion 9 attached to the top of plug
1, so that it
can move in an arc about its axis in the plane of the tidal stream and under
the force of
the stream. Such a shaft, for example, could be the drive shaft shown in my
tidal
turbine invention or an extension of it. 10 is a master hydraulic cylinder,
whose piston
rod is attached to and movable by the lower end of shaft 7. Master cylinder 10
is
connected by hoses 11, 11 to a pair of slave cylinders, 12, 12, which are
rigidly fixed
to the inside wall of plug 1. 13, 13 are rollers on the end of the piston rods
of slave
cylinders 12, 12; and 14, 14 are a pair of locking bars which are shaped to
slide into
and out of slots 15, 15, cut in the walls of plug 1 and also into and out of
slots 16, 16,
cut in the walls of socket 2. 17, 17 are angled slots in locking bars 14
within which
rollers 13, 13 can move to cause lateral movement of these bars. The upper
surfaces
of bars 14, 14 are chamfered, so that when they encounter rollers 18, 18,
attached to
the upper surfaces of slots 15, 15, they cause plug 1 to be forced downwards
within
socket 2, compressing flexible seal 19 between them at the lower end of plug
1. This
is to enable a water pump (not shown) within plug 1, to force water
efficiently
through orifice 20 in plug 1, tube 21 and conduit 22 to where its kinetic
energy can be
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CA 02678384 2009-09-09
used, when the tide is running. Plug 1 can of course incorporate an electrical
generator
instead of a pump, in which case seal 19 may not be needed.
In operation of the invention, at the tidal null point there is no lateral
force on shaft 7,
so that it takes up a vertical position. When the tide flows, it will bring
whatever is
attached to the part of shaft 7 that is above axle 8 (such as a tidal turbine)
downstream
with it, in the plane of the tidal stream. If necessary, this movement will
also rotate
plug 1 inside socket 2 so as to align slots 15 and 16 with each other. When
the part of
shaft 7 that is above axle 8 moves in the plane of the tidal stream and under
its
pressure, the part of the shaft below axle 8 will move the piston in master
hydraulic
cylinder 10 so as to force fluid through hoses 11 into slave cylinders 12. The
pressure
from this forces the piston rods in slave cylinders 12 downwards. Because
rollers 13
on the end of these rods run in slots 17, and because the slave cylinders
cannot move,
downwards movement of rollers 13 forces bars 14 laterally into slots 16 in the
wall of
socket 2. Bars 14 cannot move from there as long as the tide is running, so
that plug 1
and socket 2 are positively locked together throughout this period. This makes
it quite
impossible for the vertical component of the tidal force on anything being
held by the
anchor, to pull plug 1 out of socket 2 up to the limit of the constructional
strength of
their various parts.
At the tidal null point, because of a degree of buoyancy in the tidal turbine
or
whatever is attached to shaft 7, this shaft will return to the vertical
position. This
reverses the movement of hydraulic fluid, moving the piston rod of each slave
cylinder upwards and causing the resulting movement of rollers 13 to withdraw
bars
14 from slots 16 in socket 2. At this time, plug 1, with any equipment
attached to it,
can be freely withdrawn from socket 2 and removed for maintenance. Re-starting
of
the tidal flow in the reverse direction will then repeat the locking cycle.
There are several other ways of putting the invention into effect within the
scope of
the invention. Reciprocal movement under pressure from the tidal flow could
act upon
the locking mechanism through directly connecting rods or cables. 'The locking
system could be operated from a power source, such as an electrical battery,
incorporated in plug 1, and actuated by a timer, because future tidal
movements can
be predicted with complete accuracy, or by a remote signal.
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