WO2005061802A1

WO2005061802A1 - Drive assembly

Info

Publication number: WO2005061802A1
Application number: PCT/NL2003/000920
Authority: WO
Inventors: Hans Robbert Van Der Sluis
Original assignee: Innovative Solution Developers Bv
Priority date: 2003-12-22
Filing date: 2003-12-22
Publication date: 2005-07-07
Also published as: AU2003290458A1; EP1718807A1

Abstract

The invention pertains to a drive assembly, which drive assembly comprises: - a primary elongated member (20), which has an outer surface, and which has a longitudinal axis that extends substantially parallel to a first direction of movement (5), - a driving unit (42), for invoking movement of the primary elongated member (20), which driving unit comprises a jack (40) having a working stroke, which working stroke extends in a direction which is substantially parallel to the first direction of movement.The primary elongated member (20) is provided with a plurality of projections (21), which projections (21) project outwardly from the outer surface of the primary elongated member, the projections being distributed over a plurality of different projection planes (p), each projection plane extending at least substantially perpendicular to the first direction of movement and accommodating at least one projection, the distances (5) between adjacent projection planes being substantially constant over the length of the primary elongated member (20), projections that are arranged in different projection planes being adapted to be successively engaged by the driving unit.

Description

Drive assembly

The invention pertains to a drive assembly, which drive assembly comprises a primary elongated member, which has an outer surface, and which has a longitudinal axis that extends substantially parallel to a first direction of movement. The drive assembly also comprises a driving unit for invoking movement of the primary elongated member, which driving unit comprises a jack having a working stroke, which working stroke extends in a direction which is substantially parallel to the first direction of movement.

US 3,967,458 discloses a marine platform having telescopic legs, which telescopic legs support the platform. The telescopic legs can be varied in length, so that the platform can be put to use in a wide range of water depths. The telescopic legs comprise an inner elongated member and an outer elongated member. The inner elongated member is mounted slidably in the outer elongated member. Both elongated members are provided with arrays of holes, which arrays extend in the longitudinal direction of the elongated members .

A telescopic leg assembly according to US 3,967,458 also comprises a driving unit, which comprises a hydraulic jack. The jack engages a ring, which extends around the elongated members. This ring is provided with a plurality of pins, which pins are moveable in a plane perpendicular to the longitudinal axis of the elongated members . When the inner elongated member has to be moved with respect to the outer elongated member, the pins project through the holes of the inner elongated member. The jack engages the ring and moves the inner elongated member over a distance equal to the working stroke of the jack. The inner elongated member is then fixed with respect to the outer elongated member. The pins are then retracted out of the holes, and the jack returns to its initial position in which it is ready to move the inner member again. This way, the inner elongated member can be moved relative to the outer elongated member in a step-wise manner.

This known drive assembly suffers from several drawbacks, such as that the moveable pins have a relatively small load bearing capacity, and that they are subjected to a very large bending moment .

The object of the invention is to provide a drive assembly which is more robust than the known drive assembly.

This objective is met by the drive assembly according to claim 1.

In the drive assembly according to the invention, the primary elongated member is provided with a plurality of projections, which projections project outwardly from the outer surface of the primary elongated member. These projections are adapted to be engaged by the driving unit. It is advantageous to use projections instead of holes for this purpose, as the projections do not weaken the elongated member (which the arrays of holes do) . Also, in this construction, the elongated members can be designed in such a way that they are closed, so that no water can enter them, e.g. when the assembly is used for offshore purposes.

Moreover, the projections allow the driving unit to engage the elongated member in a direction substantially parallel to the first direction of movement. This is advantageous for the load distribution in the driving unit and allows a more compact design.

Drive assemblies of the type concerned are often used for moving objects over relatively large distances. Therefore, it can be desirable to carry out the invention as a telescopic drive assembly, which comprises at least one secondary elongated member which is adapted to at least partly accommodate the primary elongated member. The central axes of the primary elongated member and the one or more secondary elongated members are substantially parallel to each other, and preferably these central axes are coaxial to each other.

As the primary elongated member is at least partly accommodated in a secondary elongated member, the cross-sectional areas of the first and secondary elongated members differ from each other. In order to allow the driving unit to engage the projections in a direction substantially parallel to the first direction of movement, and to allow the jack to be positioned as close to the elongated member which has to be moved as possible to prevent the introduction of high bending moment, the jack of the driving unit is mounted to a support. This support allows positioning movements of the jack relative to the elongated members in a plane substantially perpendicular to the first direction of movement for adjusting the position of the jack in relation to the differences in cross-sectional dimensions between the primary elongated member and the secondary elongated member .

Preferably, the driving unit comprises a first jack and a second jack, which first jack and second jack are adapted to successively engage projections of subsequent projection planes on an elongated member. This way, the velocity of the driven elongated members can be increased.

In the embodiment wherein one or more secondary elongated members are present, as well as a first and a second jack, preferably the first jack is mounted on a primary support. The primary support allows for positioning movement of the first jack relative to the elongated members in a plane substantially perpendicular to the first direction of movement. The second jack is in this embodiment mounted on a secondary support, which secondary support allows for positioning movement of the second jack relative to the elongated members in a plane substantially perpendicular to the first direction of movement. The positioning movements of the primary support and the secondary support are adapted to adjust the positions of the first and the second jack in relation to the differences in dimensions of the cross-sectional area between the primary elongated member and the secondary elongated member.

Preferably, the drive assembly further comprises locking means, which prevent movement of at least one elongated member in the direction opposite to the first direction of movement over a distance larger than the distance between projections of two adjacent projection planes. This increases the safety.

Preferably, the locking means are adapted to support the elongated members when the supports of the jacks are moved when their position is adjusted with respect to the elongated members. This way, the jacks do not have to carry the weight of the elongated members when the position of the jacks is adjusted. It is also envisaged that for this purpose, a separate locking device is provided.

Preferably, the locking means are adapted to engage at least one projection upon which the driving unit also can engage. By adapting the locking means to engage the projections, the design of the elongated members can be kept simple, as no separate provisions have to be made for the locking means to engage the elongated member or members.

The elongated members usually will have a large longitudinal dimension compared to the dimensions of their cross-sections. Therefore, it is advantageous to provide stiffeners on the elongated members for increasing bending stiffness and for preventing local deformation of the wall of the elongated member . In order to prevent tilting of the elongated member or members, the drive assembly preferably further comprises guiding means for guiding the elongated members during their movements . More preferably, the guiding means have a working stroke that is substantially equal to the working stroke of the jack of the driving unit. This way, the guiding means do not need to extend over the entire length of the elongated members .

Preferably, each elongated member has a rectangular cross- section. In that case, the driving unit preferably comprises four sets of jacks, each set of jacks being arranged along one side of the rectangular cross-section of the elongated members. This arrangement leads to an advantageous load distribution in the drive assembly. Also, this arrangement allows high loads to be handled by the driving unit.

The driving unit preferably further comprises an interface, which is connected to at least one jack, and which is adapted to engage a projection. This interface is for example a load distribution beam, that prevents undesired load concentrations in the driving unit, in the projections and/or the elongated members .

When two or more elongated members are present, the drive assembly preferably further comprises coupling means for coupling at least two elongated members to each other in such a manner that when one of the coupled elongated members is moved by the driving unit, the other coupled elongated member moves along with the elongated member that is moved directly by the driving unit. This allows use of the drive assembly as a telescopic drive assembly.

Preferably, the drive assembly further comprises means for moving the object in a translational direction opposite to the first direction of movement. This allows the drive assembly to retract when retracting is not aided by gravity, so when the first direction of movement is other than vertically upward. The invention also pertains to a method for moving an object in a first translational direction of movement according to claim 16.

In a second aspect, the invention also pertains to a drive assembly, which drive assembly comprises: a primary elongated member, which has a longitudinal axis that extends substantially parallel to a first direction of movement, a secondary elongated member, which is adapted to at least partly accommodate the primary elongated member in such a manner that the central axis of the secondary elongated member is substantially parallel to the central axis of the primary elongated member, the secondary elongated member having a larger cross- sectional area than the primary elongated member, a driving unit, for invoking movement of the primary and/or secondary elongated member, which driving unit comprises a jack having a working stroke, which working stroke extends in a direction which is substantially parallel to the first direction of movement. The drive assembly according to the second aspect of the invention is characterised in that the jack of the driving unit is mounted on a support, which support allows for positoning of the jack relative to the elongated members in a plane substantially perpendicular to the first direction of movement for adjusting the position of the jack in relation to the differences in cross-sectional dimensions between the primary elongated member and a secondary elongated member.

The drive assemblies and the method according to the invention are particularly suitable for use for displacing and supporting large loads in vertical direction, such as in an adjustable leg for an offshore structure, which structure has to be operable in a wide range of water depths. The drive assembly and the method according to the invention are also particularly suitable for use in a multifunctional building of the type according to WO97/07305.

Drive assemblies and methods according to the different aspects of the invention will be elucidated below, with reference to the accompanying drawing, in which exemplary embodiments are shown in a non-limiting manner.

The drawing shows in: fig. 1A-D - a general overview of a platform provided with a telescopic drive assembly according to the invention, fig. 2 - a detailed view of a part of the elongated members and the driving unit according to the invention, fig. 3A-B - moveable supports of the jacks of the driving unit, fig. 4 - a cross-section of the elongated members according to line A-A of fig. 1A, fig. 5A-B - details of coupling means.

Fig. 1 shows a platform 1 that is mounted on a plurality of telescopic legs 2. Fig. 1A shows the situation in which the platform 1 is on ground level 3. Each telescopic leg is then accommodated in an associated pit 4. Each telescopic leg 2 comprises a drive assembly in the sense of the invention.

In the exemplary embodiment shown, each drive assembly comprises a first elongated member 10, a second elongated member 20 and a third elongated member 30. The first elongated member 10 has the smallest cross-sectional dimension of the elongated members 10, 20, 30. The second elongated member 20 is adapted to at least partly accommodate the first elongated member 10, so that the cross-sectional dimensions of the second elongated member 20 are larger that the cross-sectional dimensions of the first elongated member 10. The third elongated member 30 is adapted to at least partly accommodate the second elongated member 20, so that the cross-sectional dimensions of the third elongated member 30 are larger than the cross-sectional dimensions of the second elongated member 20. The elongated members 10, 20, 30 in the embodiment shown have a square cross-section, so their typical cross-sectional dimension is the length of a side of the cross-section, which typical dimension in this case is determining for the cross-sectional area.

In the exemplary embodiment shown, when moving the platform 1 in a first direction of movement 5, first the third elongated member 30 is engaged by a driving unit and moved out of the pit 4 in the first direction of movement 5. The first and the second elongated members 10, 20 remain inside the pit 4. This is shown in fig. IB.

Fig. 1C shows the following stage of moving the platform 1 in the first direction of movement 5. The second elongated member 20 is then engaged by the driving unit and moved out of the pit 4. The second elongated member 20 and the third elongated member 30 are in a fixed position relative to each other, so that the third elongated member 30 moves along with the second elongated member 20.

The last stage of moving the platform 1 in the first direction of movement 5 is shown in fig. ID. In this stage, the first elongated member 10 is engaged by the driving unit and moved out of the pit 4. The second elongated member 20 is in a fixed position relative to the first elongated member 10, and the third elongated member 30 is in a fixed position relative to the second elongated member 20.

In an alternative embodiment, which is not shown in the drawing, first the elongated member is moved out of the pit 4, followed by the second elongated member 20, and finally by the third elongated member 30.

Fig. 2 shows a part of a telescopic leg 2 in more detail. As is clear from fig. 2, the cross-sectional dimensions of the elongated members 10, 20, 30 allow that the second elongated member 20 is accommodated in the third elongated member 30, and that the first elongated member 10 is accommodated in the second elongated member 20.

Each elongated member 10, 20, 30 is provided with projections 11, 21, 31 respectively. These projections 11, 21, 31 extend from the outer surface of the elongated members 10, 20, 30 respectively, and are arranged in projection planes P that extend at least substantially perpendicular to the first direction of movement 5. The projections 11, 21, 31 can extend around the entire circumference of the respective elongated member 10, 20, 30, or around a part thereof. This is also shown in fig. 4.

As can be seen in fig. 2, the distances between adjacent projection planes P are substantially constant over the length of the respective elongated member 10, 20, 30.

In the situation of fig. 2, the driving unit engages the second elongated member 20. The driving unit comprises hydraulic jacks 40. In total, eight hydraulic jacks 40 are present; they are arranged in four sets (each of which has two jacks) , such that hydraulic jacks 40 of the same set are located adjacent to the same face of the elongated member 10, 20, 30 to be engaged.

The hydraulic jacks 40 have a working stroke that is essentially equal to the distance S between projection planes P of a single elongated member. In operation, all hydraulic jacks 40 have the same working stroke. The hydraulic jacks 40 are arranged such that their working stroke extends substantially in the first direction of movement 5. Instead of hydraulic jacks 40, other types of jacks 40 can be used.

In the embodiment of fig. 2, guiding means 41 are present. In the embodiment shown, four guiding means 41 are present. They are located between hydraulic jacks 40 of the same set. However, it is also possible to use a different number of guiding means 41 and/or to locate them at a different position. The guiding means 41 in this exemplary embodiment are designed as a first tube, which is located in a second tube. The tubes are moveable with respect to each other in their longitudinal direction. The guiding means 41 are arranged such that the longitudinal direction of the tubes is parallel to the first direction of movement 5. The tubes of the guiding means 41 can be moved relative to each other over a distance that is at least equal to the working stroke of the jacks 40, without the tubes disengaging each other.

The hydraulic jacks 40 of a single set and the associated guiding means 41 are in the embodiment of fig. 2 all attached to a load distribution beam 42. This load distribution beam 42 is adapted to engage the projections 11, 21, 31 of the elongated members 10, 20, 30 respectively. Its purpose is to prevent undesirable load concentrations in the elongated members 10, 20, 30 and/or in the driving unit.

Preferably, the hydraulic jacks 40 of the same set and the guiding means 41 associated with them are mounted against a kerb 44. This kerb 44 takes up any forces in the plane perpendicular to the first direction of movement 5.

The driving unit further comprises tilting devices 43. The tilting devices 43 are adapted to pivot the hydraulic jacks 40 and the guiding means 41 away from and, in a different operational stage towards, the projections 11, 21, 31. In the embodiment shown, the tilting devices 43 are hydraulic cylinders, pivoting the hydraulic jacks 40 of the same set and the associated guiding means 41 at the same time.

The jacks 40 are located at an offset with respect to the adjacent wall of an elongated member. Although the guiding means prevent that a bending moment due to this offset is applied to the jacks, the driving unit as a whole is subjected to this bending moment. The direction of the bending moment is such that in the case that the load distribution beam 42 does not engage the projection 11, 21, 31 entirely, the load distribution beam 42 is forced towards the elongated member, so that a better grip on the projection 11, 21, 31 is obtained. This increases the inherent safety of the drive assembly.

The hydraulic jacks 40 are mounted on supports. In the embodiment of fig. 2, there are two types of supports: primary supports 51 and secondary supports 52. Each support 51, 52 supports the two jacks 40 of a single set and the guiding means 41 associated with this set. There are two primary supports 51 and two secondary supports 52. The supports of the same type are arranged on opposite sides of the elongated member.

The secondary supports 52 are mounted onto the primary supports 51, and the primary supports 51 are mounted onto stationary supports 50. The secondary supports 52 are moveable with respect to the primary supports 51 towards and away from the elongated members 10, 20, 30, in a plane perpendicular to the first direction of movement 5. Also, the primary supports 51 are moveable with respect to the stationary supports 50 towards and away from the elongated members 10, 20, 30, in a plane perpendicular to the first direction of movement 5. Preferably, the primary supports 51 are moveable in a second direction, and the secondary supports 52 are moveable in a third direction.

More preferable, the first direction of movement 5 of the drive assembly, the second direction and the third direction are all perpendicular to each other.

The primary and the secondary supports 51, 52 can be driven in various ways, such as by means of hydraulic cylinders or by electric motors .

Fig.2 also shows locking means for preventing movement of the first elongated member 10 in the direction opposite to the first direction of movement 5. The locking means comprise cams 63 on two primary locking beams 61 and two secondary locking beams 62. The locking beams of the same type are located on opposite sides of the elongated members 10, 20, 30. The primary locking beams 61 and the secondary locking beams 62 are moveable in a plane perpendicular to the first direction of movement 5.

The drive assembly of fig. 2 can be operated in various modes. In the first mode of operation, all four load distribution beams 42 engage a projection 11, 21, 31 of a first projection plane P of the same elongated member 10,20,30. In the case of a projection 11, 21, 31 that extends around the entire circumference of the respective elongated member 10, 20, 30, the load distribution beams 42 all engage the same projection 11, 21, 31. It is however also envisaged that a separate projection is present on each wall of the elongated member (in the same projection plane) . In the situation of fig.2, they engage a projection 21 on the second elongated member 20.

Then, all jacks 40 are actuated at the same time to perform their working stroke. Together, they move the respective elongated member 10, 20, 30 over the length of their working stroke as they engage the respective projection 11, 21, 31. The guiding means 41 make sure that the movement of the respective elongated member is straight and directed in the first direction of movement 5.

At the end of the working stroke of the jacks 40, the position of the elongated member that has been moved by the jacks 40 is fixed in the direction opposite to the first direction of movement 5. In the first mode of operation, the position is fixed by separate fixing means (not shown in fig. 2) .

While the position of the elongated member is fixed, each tilting means pivots the set of hydraulic jacks 40 and the associated guiding means 41 away from the elongated member in accordance with arrow T. The load distribution beams 42 no longer engage the projection or projections 11, 21, 31 they did when lifting the elongated member. After or during the pivoting, the jacks 40 and the guiding means 41 are retracted to the beginning of the working stroke. They are then pivoted back towards the elongated member. As the jacks 40 and the guiding means 41 now have a smaller length, the load distribution beams 42 come to engage a projection which is in a second projection plane, the second projection plane being adjacent to the first projection plane.

When the fixation of the position of the elongated member is released, the jacks 40 can move the elongated member over a next stroke.

As the separate fixing means, locking means 61,62 can be used.

In a second, different mode of operation, the sets of jacks 40 operate in groups. The groups consist of set of jacks 40 that are located on opposite sides of the elongated member. While the first group of jacks 40 is retracted, the second group of jacks 40 fixes the position of the elongated member in the direction opposite to the first direction of movement 5. The first group of jacks 40 then engages the projection or projections of the next projection plane and moves the elongated member over another stroke. The second group of jacks 40 pivots away, and the jacks 40 of that group are retracted. Now, the first group of jacks 40 fixes the elongated member until the second group of jacks 40 is ready to move the elongated member over the next stroke. In this second mode of operation, the driving speed of the elongated members is higher than in the first mode of operation.

In a third mode of operation, the jacks 40 on a single side of the elongated member engage a projection, while the jacks on the other three sides do not. Alternatively, it is also envisaged that jacks 40 on two adjacent sides of the elongated member engage a projection while the jacks on the other two sides do not. The engaging jacks apply a resultant force to the projection in the first direction of movement 5. As the jacks 40 apply the force eccentrically with respect to the centre line of the elongated member, a bending moment is applied to the elongated member, resulting in a force onto the elongated member in a plane perpendicular to the first direction of movement 5.

If this third mode of operation is used when the drive assembly is a telescopic leg of a platform, the force perpendicular to the first direction of movement can be applied for controlling the position of the platform in the plane perpendicular to the first direction of movement, so that active positioning of the platform in this plane can be achieved.

For moving the elongated member back into the direction opposite to the first direction of movement 5, several methods can be applied. This movement can be aided by gravity, or separate retracting means can be present. These retracting means can be for example a cable co-operating with a drum or winch. It is also envisaged that for retracting the elongated members 10, 20, 30, the method for moving the elongated member in the first direction of movement 5 is reversed.

Fig. 3A shows the first elongated member 10 in cross-section, and fig. 3B shows the third elongated member 30 in cross- section. As is clear from a comparison of fig. 3A and fig. 3B, the third elongated member 30 has a larger cross-section than the first elongated member 10. The second elongated member 20 (not shown in fig. 3) has cross-sectional dimensions that lie between those of the first and of the second elongated member 20.

The jacks 40 are preferably loaded centrally in a direction parallel to their working stroke. Especially hydraulic jacks are sensitive to bending moments applied to them, as bending moments can damage the jacks. However, bending moments on the driving unit cannot be avoided as the jacks are arranged eccentrically with respect to the elongated members. The guiding means 41 and the load distribution beam 42 are designed to take up the bending moment (which results in a torque in the load distribution beam 42) introduced in the driving unit this way, but it is advantageous that this bending moment is kept as small as possible. For this reason, the position of the jacks 40 has to be adjusted with respect to the elongated member when a different elongated member, with different cross-sectional dimensions has to be engaged by the driving unit.

This adjustment is preferably achieved by mounting the jacks 40 onto movable supports. Fig. 3 shows four sets of jacks: 40*, 40**, 40' and 40''. Jacks of a single set are arranged in such a way that they face the same face of the elongated member.

Jacks 40* and 40** are mounted on primary supports 51. The primary supports 51 are moveable with respect to the stationary supports 50 in the direction Dl. By moving the primary supports 51 relative to the elongated member in the direction Dl, the position of the jacks 40* and 40** can be adjusted so that the jacks 40* and 40** are not or largely not submitted to bending moments .

Jacks 40' and 40'' are mounted on secondary supports 52. The secondary supports 52 are moveable with respect to the primary supports 51 in the direction D2. By moving the secondary supports 52 relative to the elongated member in the direction D2, the position of the jacks 40' and 40'' can be adjusted so that the jacks 40' and 40'' are not or largely not submitted to bending moments .

A similar principle can be applied to locking means that comprise locking beams 61, 62, which locking means confine the elongated members and hence prevent movements of an elongated member in a direction in or opposite to the first direction of movement 5. The locking means comprise primary locking beams 61 and secondary locking beams 62. The secondary locking beams 62 are moveable relative to the primary locking beams 61, and the primary locking beams 61 are moveable relative to the locking beam supports 60. The locking beams 61, 62 are moveable in a plane that is perpendicular to the first direction of movement 5. The movements of the locking beams 61,62 allow the locking means to be adjusted with respect to the different cross- sectional dimensions of the different elongated members.

Preferably, the locking beams 61, 62 are arranged at a different level with respect to the elongated member, as shown in fig. 2. Preferably, the locking means are arranged in such a way that a primary locking beam 61 faces the same side of the elongated member as a secondary support 52, and that a secondary locking beam 62 faces the same side of the elongated member as a primary support 51. Preferably, the locking beam supports 60 are arranged with respect to the stationary supports 50 as shown in fig.3A and 3B, that is: the stationary supports 50 arranged on two opposite sides of the elongated member, and the locking beam supports 60 on the other two opposite sides of the elongated member. This arrangement allows an efficient use of building space.

Fig. 4 shows a cross-section of the elongated members 10, 20, 30 according to line A-A of fig. 1A. The elongated members 10, 20, 30 in this exemplary embodiment have a rectangular outer wall, e.g. of suitable steel plates, internally provided with stiffeners 12, 22, 32 for increasing the resistance against bending of the elongated members 10, 20, 30.

Also in the preferred embodiment of fig. 4, the elongated members 10, 20, 30 are provided with additional guiding means 70. In case of elongated members 10, 20, 30 having a rectangular or even square cross-section, it is advantageous to arrange the additional guiding means 70 at or near the a corner of the elongated member 10, 20, 30 to ensure proper guiding in all degrees of freedom in the plane perpendicular to the first direction of movement 5. As additional guiding means 70, plates 72 are attached to the first and second elongated members 10, 20, preferably over their entire length. Each plate 72 runs in a generally U-shaped profile 73, that is arranged onto the second, third elongated member 20, 30 respectively. The profile 73 guides the plate 72 of the adjacent elongated member, as can be seen in fig. 4.

When two elongated members 10, 20, 30 are to be moved simultaneously, they preferably are connected to each other. Preferably, this is achieved by a coupling means between the elongated members 20 and 30 as shown in fig. 5. In a similar way, the elongated members 10 and 20 can be connected to each other.

Fig. 5 shows a longitudinal section of the wall 35 of the third elongated member 30. On the inside of the wall 35, a stiffener 32 according to fig. 4 is arranged. In this exemplary embodiment, the projections 31* extends not only outside wall 35, but also to the inside of the wall 35.

Fig. 5 also shows a longitudinal section of the wall 25 of the second elongated member 20. On the inside of the wall 25, a stiffener 22 according to fig. 4 is arranged. In this exemplary embodiment, the projections 21* extends not only outside wall 25, but also to the inside of the wall 25. The projections 21* are only shown in fig. 4 and not in fig. 5, as they are preferably located at a different level from the projections 31*.

Onto the stiffener 32 on the inside of the third elongated member 30, a coupling member 80 is arranged. This coupling member 80 is pivotable around axis 81. The coupling means further comprises an actuator member 82. The actuator member 82 comprises a recess 83, in which the coupling member 80 is present. Member 82 is preferably stopped by a rim 84 on member 80. Fig. 5A shows the coupling means in their active position, which means that the adjacent elongated members have a fixed position relative to each other in and/or opposite to the first direction of movement 5. Actuator member 82 is in a first position, close to the projection 31* of the third elongated member 30, This causes the coupling member 80 to pivot towards the second elongated member 20. The coupling member 80 engages or largely engages projection 21. In this position the coupling member 80 largely prevents relative movement of the third elongated member 30 and the second elongated member 20 in and/or opposite to the first direction of movement 5.

In fig. 5B, the coupling means are in their inactive position, which allows relative movement of the third elongated member 30 and the second elongated member 20 in and/or opposite to the first direction of movement 5. In this position, the actuator member 82 is moved away from the projection 31* of the third elongated member 30. This causes the coupling member 80 to pivot towards the third elongated member 30, so no force can be transferred from the third to the second elongated member 20 and vice versa. A stop-rim 84 prevents the actuator member 82 from sliding off the coupling member 80.

The position of the actuator member 82 can be changed by means of operating means 85. This can be for example a cable, a chain or a rod. Gravity can be used to transfer the actuator member 82 from the first to the second position.

The drive assembly according to the invention is suitable for use in a multifunctional building of the type according to

WO97/07305. The drive assembly according to the invention is especially suitable for use in a sports stadium, in which sports stadium a member is present which is moveable in a vertical direction. Such a member can be used as a sports field when it occupies a low position, with the stands arranged around the sports field. In a high position, the member can be used as a roof for the stadium, allowing indoor activities. In such a stadium, it is advantageous to use the drive assembly for moving the member, as the drive assembly can be placed under the member so that when the member occupies a low position, no poles or the like obstruct the view of the spectators on the sports field.

Claims

1. Drive assembly, which drive assembly comprises: a primary elongated member, which has an outer surface, and which has a longitudinal axis that extends substantially parallel to a first direction of movement, a driving unit, for invoking movement of the primary elongated member, which driving unit comprises a jack having a working stroke, which working stroke extends in a direction which is substantially parallel to the first direction of movement, characterised in that, the primary elongated member is provided with a plurality of projections, which projections project outwardly from the outer surface of the primary elongated member, the projections being distributed over a plurality of different projection planes, each projection plane extending at least substantially perpendicular to the first direction of movement and accommodating at least one projection, the distances between adjacent projection planes being substantially constant over the length of the primary elongated member, projections that are arranged in different projection planes being adapted to be successively engaged by the driving unit, the distances between adjacent projections being substantially constant over the length of the primary elongated member and being substantially equal to the working stroke of the jack of the driving unit.

2. Drive assembly according to claim 1, characterised in that, the drive assembly further comprises at least one secondary elongated member, which has an outer surface, and which is adapted to at least partly accommodate the primary elongated member in such a manner that the central axis of the secondary elongated member is substantially parallel to the central axis of the primary elongated member, the secondary elongated member having a larger cross-sectional area than the primary elongated member, the secondary elongated member being provided with a plurality of projections, which projections project outwardly from the outer surface of the secondary elongated member, the projections being distributed over a plurality of different projection planes, each projection plane extending at least substantially perpendicular to the first direction of movement and accommodating at least one projection, the distances between adjacent projection planes being substantially constant over the length of the secondary elongated member, projections that are arranged in different projection planes being adapted to be successively engaged by the driving unit, the distances between adjacent projections being substantially constant over the length of the secondary elongated member and being at least substantially equal to the working stroke of the jack of the driving unit, and in that the jack of the driving unit is mounted on a support, which support allows for movement of the jack relative to the elongated members in a plane substantially perpendicular to the first direction of movement for adjusting the position of the jack in relation to the differences in cross-sectional dimensions between the primary elongated member and a secondary elongated member.

3. Drive assembly according to any of the preceding claims, characterised in that, the driving unit comprises a first jack and a second jack, which first jack and second jack are adapted to successively engage projections of subsequent projection planes on an elongated member .

4. Drive assembly according to claims 2 and 3, characterised in that, the first jack is mounted on a primary support, which primary support allows for positioning of the first jack relative to the elongated members in a plane substantially perpendicular to the first direction of movement, and in that the second jack is mounted on a secondary support, which secondary support allows for positioning of the second jack relative to the elongated members in a plane substantially perpendicular to the first direction of movement, so that the primary support and the secondary support allow to adjust the position of the jacks in relation to the differences in cross-sectional dimensions between the primary elongated member and a secondary elongated member.

5. Drive assembly according to any of the preceding claims, characterised in that, the drive assembly further comprises locking means, which prevent movement of at least one elongated member in the direction opposite to the first direction of movement over a distance larger than the distance between projections of two adjacent projection planes.

6. Drive assembly according to claim 5, characterised in that, the locking means are adapted to engage at least one projection on an elongated member.

7. Drive assembly according to any of the preceding claims, characterised in that, at least one elongated member is provided with stiffeners for increasing resistance against bending of that elongated member.

8. Drive assembly according to any of the preceding claims, characterised in that, the drive assembly further comprises guiding means for guiding the elongated members during their movements in the first direction of movement.

9. Drive assembly according to claim 8, characterised in that, the guiding means have a working stroke that is substantially equal to the working stroke of the jack of the driving unit.

10. Drive assembly according to any of the preceding claims, characterised in that, each elongated member has a rectangular cross-section.

11. Drive assembly according to claim 10, characterised in that, that the driving unit comprises four sets of jacks, each set of jacks being arranged facing one side of the rectangular cross- section of the elongated members.

12. Drive assembly according to any of the preceding claims, characterised in that, the driving unit further comprises an interface, which is connected to at least one jack, and which is adapted to engage a projection.

13. Drive assembly according to claim 2, characterised in that, the drive assembly further comprises coupling means for coupling at least two elongated members to each other in such a manner when one of the coupled elongated members is moved by the driving unit, the other coupled elongated member moves along with the elongated member that is moved directly by the driving unit.

14. Drive assembly according to any of the preceding claims, characterised in that, the drive assembly further comprises means for moving the object in a translational direction opposite to the first direction of movement .

15. Drive assembly according to any of the preceding claims, characterised in that, the first direction of movement is a vertical direction.

16. Method for driving in a first translational direction of movement which method comprises: engaging a first projection on the outer surface of an elongated member by means of a driving unit, the driving unit comprising a first jack, actuating the first jack so that the first jack moves outwardly to its full working stroke, taking the elongated member with it, thus causing the elongated member to move, - fixing the elongated member in the direction opposite to the first direction of movement, pivoting the first jack outwardly in order to disengage the driving unit from the first projection, retracting the first jack back to its initial length, - pivoting the first jack inwardly so that it engages a second projection of the elongated member, which second projection is adjacent to the first projection, releasing the fixation of the elongated member.

17. Method according to claim 16, characterised in that, the elongated member is fixed in the direction opposite to the first direction of movement using a second jack of the driving unit, which second jack is adapted to move the elongated member further in the first direction of movement while the first jack is retracted.

18. Method according to claim 16 or 17, characterised in that, the method further comprises the step of adjusting the position of the jack with respect to a cross-sectional dimension of an elongated member.

19. Offshore structure in which a drive assembly according to any of the claims 1-15 is incorporated in at least one supporting leg of the structure.

20. Building structure, e.g. a sports stadium, which comprises a member, e.g. a sports field providing member, which is moveable in a vertical direction, which member is adapted to be driven by a drive assembly according to any of the claims 1- 15.

21. Drive assembly, which drive assembly comprises: a primary elongated member, which has a longitudinal axis that extends substantially parallel to a first direction of movement, a secondary elongated member, which is adapted to at least partly accommodate the primary elongated member in such a manner that the central axis of the secondary elongated member is substantially parallel to the central axis of the primary elongated member, the secondary elongated member having a larger cross- sectional area than the primary elongated member, a driving unit, for invoking movement of the primary and/or secondary elongated member, which driving unit comprises a jack having a working stroke, which working stroke extends in a direction which is substantially parallel to the first direction of movement, characterised in that, the jack of the driving unit is mounted on a support, which support allows for positioning of the jack relative to the elongated members in a plane substantially perpendicular to the first direction of movement for adjusting the position of the jack in relation to the differences in cross-sectional dimensions between the primary elongated member and a secondary elongated member.