GB2041096A

GB2041096A - Wave energy apparatus

Info

Publication number: GB2041096A
Application number: GB8001223A
Authority: GB
Original assignee: FALNES J
Current assignee: FALNES J
Priority date: 1979-01-15
Filing date: 1980-01-14
Publication date: 1980-09-03
Also published as: AU522045B2; DE3001284A1; DE3001284C2; NO145630B; GB2041096B; SE8000255L; NO790121L; NO145630C; AU5459080A; FR2446390B1; FR2446390A1; JPS55101774A

Abstract

An apparatus for conversion of water wave energy comprising at least two members (1, 2) which are adapted to be at least partially submerged in the water and so interconnected (at 3) as to permit relative oscillating movements of the members. In order to obtain a maximum utilisation of the wave energy, the connecting means between the two members in a pair comprises a device (4, 5) adapted to lock the two members relatively to each other whereby the natural period of the combined two members (1, 2) is increased relatively to the average natural period of the waves. The locking device is operative until just before the wave motion reaches its greatest displacement and is then released so that member 1 moves rapidly relative to member 2. The locking device is re-engaged when the relative velocity of members 1 and 2 is a minimum. <IMAGE>

Description

SPECIFICATION An apparatus adapted to absorb or to utilise the energy of water waves The present invention relates to an apparatus adapted to absorb or to utilize the energy of waves in water, comprising at least two members which are at least partially submerged in the water and are interconnected in such a manner that they in pair may perform oscillating rectilinear or rotational movements relatively to each other.

To that end there has been suggested an apparatus in which a member which is at least partially submerged in the water, is locked relatively to solid ground during selectable time periods of each cycle of such waves to which the apparatus be subjected.

According to the present invention there is provided an apparatus comprising at least two members which are to be at least partially submerged in the water and are so interconnected as to permit the members in pair to perform oscillating movements, means being provided for a periodical interlocking of the two members in a pair, so that the movements of the members relatively to each other be so controlled that a maximum utilisation of the wave energy be obtained.

The enclosed drawings illustrate, schematically and by way of example, two embodiments of an apparatus in which the principle of the present invention is adapted.

Figure 1 is a vertical sectional view of an apparatus in which two members may perform an oscillatory rectilinear movement relatively to each other.

Figure 2 is a vertical sectional view of an apparatus in which two members may perform an oscillatory rotational movement relatively to each other.

Figure 3 is a view as seen from the left in Fig. 2 of the same apparatus as shown in that figure.

The apparatus shown in Fig. 1 comprises a conical hollow member 1 which in the cavity surrounds a cylindrical, hollow member 2 which is closed at the top and open at the bottom and is vertically positioned in the water, to the effect that an air cushion is formed at the top. The two members may slide vertically relatively to each other through casters or wheels 3 and a device 4 which is so controllable that the members 1 and 2 may be periodically locked relatively to each other.

When the member 2 is partially submerged, as shown in the drawing, waves which strike against the apparatus will cause the member 1 to slide up and down along the member 2, whereas the member 2 is kept substantially stationary due to the substantial submersion of the member. This relative movement of the two members may be utilized for the generation of useful energy, for instance through a linear electric generator, a rotating hydraulic pump or other apparatus known per se and not shown in the drawing. If hereby no particular measure be taken, such relative movements of the two members will be performed in step with the wave motions and are relatively small, so that the obtainable useful energy also is small.

A measure which may bring about an essential increase in the output energy of the apparatus, consists in an interlocking of the two members by means of the device 4 during selected time periods of each wave cycle. As the member 2 is water filled and consequently has a relatively high oscillation mass, while the member 1, when oscillating freely, has a natural period which is shorter than the average wave period, the two members, when interlocked, will have a natural period of the vertical movement which is longer than the average wave period.

When an apparatus having interlocked members 1 and 2 is subjected to the influence of a wave, and the interlocking is released just before the wave reaches its greatest amplitude, the member 1 will move relatively quickly upwards along the member 2 while the wave force has about its greatest value. When hereby the member 1 reaches its utmost position, immediately before its motion direction is reversed, that is when the velocity of member 1 relatively to member 2 is nil, the locking device is again closed so that the two members together move in the reversed direction.The velocity is at first small, but increases slowly with the increasing wave force in this opposite direction, until the locking device is again released when the wave force approaches its highest value in this direction, so that the member 1 may freely continue its motion, now also relatively to the member 2, such as just described in connection with the first extreme position.

When the apparatus is controlled by means of the locking device in the manner described, the effect which is absorbed and which may be given off, and which corresponds to the product of the wave force on the member 1 and the velocity of this member, will always be positive and approximately of its greatest possible value.

The apparatus described is in particular adapted when the waves which influence the apparatus are scarcely regular in wave length and/or amplitude.

Figs. 2 and 3 illustrate a second embodiment of the apparatus according to the invention, in which two rectangular members 1 and 2 are pivotably interconnected at 3 and each in the form of a rectangular sheet, the sheet 1 being very light, while the sheet 2 is relatively heavy and the whole apparatus is kept floating, in partially submerged position by the buoyancy of the member 1. In addition to the pivot connection 3, the members 1 and 2 are interconnected by means of a rod 5 or the like, one end of which is connected by means of a rod 5 or the like, one end of which is connected to the lower portion of the member 2 through a pivot 6, while the other end is carried by a locking device 4 which is pivotably mounted at the top edge of the member 1.

The member 1 is so made and shaped that it has a natural period of oscillation about the pivot 3 which is smaller than the average wave period, while the natural period of interlocked members 1 and 2 is greater than the average wave period, due to the great moment of inertia of the member 2.

The manner of operation of the apparatus, i.e. the control of the locking device 4, is the same as that of the apparatus shown in Fig.

1, as the member 1 will oscillate together with the member 2 when the locking device is closed, and oscillate relatively to the member 2 when the locking device is released. This oscillation of the two members relatively to each other is utilized for the absorbtion of the energy in the incoming waves, for instance by means of a rotating electrical generator or a hydraulic pump which is associated with the pivot 3.

In both the embodiments of the apparatus shown it comprises a pair of cooperating members 1 and 2, but it is obvious that the apparatus may comprise a number of such pairs. Hereby, one of the members, in particular the member 2 may possibly be common to two pairs, or the member 1 of Figs. 2 and 3 may be split into two parts which are pivotably interconnected about a horizontal axis and connected through a locking device in addition to and similar to that shown and described above.

It is also obvious that the rod connection of the embodiment shown in Fig. 2 and 3 may be replaced by a clutch, for instance a magnetic clutch in the pivot 3.

Claims

1. An apparatus for the conversion of the energy in water waves, comprising at least two members which are to be at least partially sumberged in the water and are so interconnected as to permit the members in pair to perform relative oscillating movements, characterised therein that the connecting means between the members in the pair comprises a device adapted to lock the two members relatively to each other during selected time periods of each wave cycle.

2. An apparatus as claimed in claim 1, characterised in that the two members in a pair are in the form of a hollow annular cone slidably surrounding a hollow cylinder, a locking device being provided between the members for the purpose of temporarily preventing rectilinear relative movements of the members.

3. An apparatus as claimed in claim 1, characterised in that the two members in a pair are in the form of two hollow plates pivotably interconnected about a horizontal axis, a locking device being provided between the two plates in a pair for the purpose of temporarily preventing relative oscillating movements of the two members about the said horizontal pivot axis.

4. An apparatus for the conversion of the energy in water waves substantially as hereinbefore described with reference to and as shown in the accompanying drawings.