IES84080Y1 - Tidal current/tidal stream electrical generator - Google Patents

Description

A tidal stream generator This invention relates to a tidal stream generator, powered by the movement of water through blades, with power generated equally in forward and reverse flow at a constant rate of output.

One of the major problems with underwater generators is the ability to generate power with the change in direction of water flow and to maintain power with change in speed.

It is the object of this invention to provide electrical power at a constant rate of output by spinning a turbine via blades that are prone to the oncoming water. A series of hydraulic controls and a governor will vary the pitch of the blades to the oncoming water to automatically adjust power output at a constant rate with minimum downtime. The blades will further be able to spin in either direction and keep generating electricity with the reverse shift in a tidal stream. The entire generator assembly will sit on a submersible platform that can be raised for routine maintenance.

According to the invention, there is provided a tidal stream generator compromising a blade array connected to a hydraulic pump, a hydraulic motor, an electrical generator, a governor and a blade control mechanism, characterised in that - the blade array consists of two or more blades, each with a control mechanism to rotate them about their individual rotational axes — a shaft connecting the blade array to a hydraulic pump, via a gearbox — a hydraulic pump that has its send line connected to a hydraulic motor and its return line connected to a sump — a hydraulic motor connected to an electrical generator — an electrical generator that turns, via a gear, a shaft connected to a flyweight governor and electrical power is taken from the generator — a flyweight governor that operates a shaft allowing fluid to flow from the high pressure line from the hydraulic pump to the sump, or, with higher rotation, to the control mechanism on the blade array _ — the hydraulic pump, hydraulic motor, generator, governor and control mechanisms are encased in a protective housing, with the blade array protruding to interact with the oncoming water — electrical power is taken via a cable to the desired location In one embodiment, the tidal stream generator is connected to a pylori and fastened to a fixed point.

In another embodiment, the tidal stream generator is connected to a pylon which is connected to a submersible base, which is lowered and raised by internal ballast tanks.

In another embodiment, multiple tidal stream generators are mounted on pylons on one submersible base.

The invention will be more clearly understood from the following description, given by way of example only, with reference to the accompanying figures in which Fig. 1 is a side View of the invention Fig. 2 is a side view of the interior working of the power generation mechanism Fig. 3 is a cross—sectional and side view of the working of the rotational speed governor Fig. 4 is a cross—sectional and side View of the blade pitch control mechanism Referring to the drawings, Figure 1 shows the tidal stream generator (1) of the invention mounted on a pylon (2) attached to a submersible base with hollow chambers (3).

The interior workings of the impulse turbine device are shown in Figure 2. Blades (4) are attached to a central shaft (5) and turn a hydraulic pump (7) via a gearbox (6). The pressurised fluid is then pumped to a motor (8) Via a send-line (9) and the low pressure fluid is taken from a sump (10) via a return—line (11). The motor turns by fluid flow from the send-line (9) to a return-line (12), which is connected to the sump. The motor turns a shaft (13), which turns an electrical generator (14) within specified speed ranges. The shaft (13) that turns the electrical generator continues through the generator and terminates with a gear (15). This transmits rotational energy to another gear (16).

As shown in greater detail in Figure 3, the gear (16) is connected to a governor shaft (17). This shaft is moved in and out of a box (18) along its own rotational axis as determined by the movement of a flyweight governor (19). Into the box (18) go a send-line (9) from the hydraulic pump and two lines come out, one (20) to the sump and one (21) to the blade control mechanism. Under normal rotation, the fluid in the system flow into the pump. With increasing rotation, flyweights (22) in the governor fly out radially, as indicated by the arrows, and push on the governor housing, acting against a spring (23), and the shaft is pulled into a second position, allowing fluid to travel from send-line (9) to line (21) and on to the blade pitch control mechanism.

The blade control mechanism is best shown in Figure 4. Fluid is taken from the governor mechanism and fed into a hollow section of the central shaft (5) through a pin—hole that is encapsulates by a box (24). This fluid flow, which is shown with arrows, pushes on a cap (25), which rotates the blades (4) via linkages (26), as shown by the arrows going around the blades (4).

This rotating action ‘feathers’ the blades i.e. it shows less blade to the oncoming water. This in turn leads to less rotation of the turbine and governor. The flyweights in the governor return to their original position and the fluid in the governor box is routed back to the sump and not to the blades, which allows them to return to where they were before, by a spring force from springs (27) that counteract the linkages.

This constant adjustment of the blades to suit the rotation of the generator results in a constant revolution of the generator and, consequently, constant power.

The blades are of a simple impulse type and turn with equal efficiency with an opposite direction of water flow. With a change in water flow, the entire system will work while spinning in the opposite direction.

Power is transferred ashore by means of underwater marine cables (28) for grid connection.

The invention is not limited to the embodiments described, but may be varied in construction and detail within the scope of the claims.

Claims (5)

Claims

1. A tidal stream generator (1) comprising a blade array (4) connected to a hydraulic pump (7), a hydraulic motor (8), an electrical generator (14), a governor (19) and a blade control mechanism, characterised in that the blade array consists of two or more blades (4), each with a control mechanism to rotate them about their individual rotational axes a shaft (5) connects the blade array to a hydraulic pump (7), via a gearbox (6) the hydraulic pump has its send-line (9) connected to a hydraulic motor (8) and its return—line (11) connected to a sump (10). the hydraulic motor connects to a shaft (13) that turns an electrical generator (14). and electrical power is taken from the generator via a cable (28) the shaft (13), is terminated by a gear (15) and turns, via a gear (16), a governor shaft (17) connected to a flyweight governor (19) the governor shaft spins inside a box (18) flyweights (22) in the governor splay outwards with rotation and push against the governor housing and compress a spring (23) , which moves the shaft (17) allowing fluid to flow from the send—line (9) from the hydraulic pump (7) to line (20) and on to the sump (8) under normal conditions, or, with higher rotation, to line (21) and on to the control mechanism on the blade array through a box (24) and into the blade shaft (5) a cap (25) on the blade shaft is connected to linkages (26) to the blades (4), and the force of the linkages is counteracted by springs (27) electrical power is taken via a cable (28) to the desired location

. A tidal stream generator as claimed in the preceding claim, wherein the apparatus (1) further comprises a pylon (2) to attach the tidal stream generator to a fixed point.

. A tidal stream generator as claimed in any preceding claim wherein the apparatus (1) further comprises a tidal stream generator attached to a pylon (2), which is in turn attached to a submersible platform (3), that can be raised or lowered by using internal ballast tanks.

. A tidal stream generator as claimed in any preceding claim wherein multiples of the apparatus (1) are attached to pylons (2), which are attached to a submersible platform (3). U:

5. A tidal stream gener to the drawings. ator substantially as described with reference