The invention relates to a ball joint coupling for pivotally coupling two pipe parts, which ball joint coupling comprises :

- a first coupling part with a central passage and an at least partially ball-shaped outer surface;

- a second coupling part with an axially extending, central passage and an at least partially socket-shaped inner surface which corresponds with the at least partially ball shaped outer surface in order to form a ball joint;

wherein the second coupling part comprises a base part arranged around the central passage, and locking segments arranged around the central passage and pivotally on the base part, which locking segments each have a socket-shaped surface part,

wherein the socket-shaped surface parts form at least a part of the at least partially socket-shaped inner surface of the second coupling part,

wherein the locking segments are each pivotable around a tangential pivot axis between a first position, wherein the socket-shaped surface parts of the locking

segments lie against the ball-shaped outer surface of the first coupling part, and a second position wherein the locking segments release the first coupling part for uncoupling of the second coupling part; and

- a blocking ring which extends around the second coupling part and is axially displaceable between a blocking position, in which the blocking ring encloses the locking segments in the first position and blocks the pivoting

movement of the locking segments, and a release position for releasing the locking segments. Such a ball joint coupling is known from US 3997197 and is used in a dredging line, which is placed floating on the water between a dredging vessel and for instance the shore. Such a dredging line is formed from pipe sections which are mutually connected with fixed couplings and such ball joint couplings.

Because dredging lines are usually in the water for a long time, fouling will accumulate on the couplings, and they will become contaminated, after a period of time. In the known ball joint coupling according to US 3997197 it is difficult in such a situation to open the coupling again when a pipe section has to be released. Because the locking

segments tilt round a protrusion in the centre, a space between the locking segment and the base part will become smaller when the locking segments pivot to the second

position. When fouling and dirt are present in the space, this obstructs the pivoting movement of the locking segment, whereby opening of the known ball joint coupling is impeded.

It is therefore an object of the invention to reduce or even obviate the above stated drawbacks.

This object is achieved according to the invention with a ball joint coupling according to the preamble, which is characterized in that a hinge is arranged between a first axial end of each locking segment and the base part, wherein the tangential pivot axis is formed by the hinge.

Because the hinge is arranged on the first axial end of a locking segment, no space will be reduced when the locking segment is opened. All fouling and dirt will be brought along when the locking segment is opened and will not be pressed into a cavity, which may impede the pivoting movement of the locking segment.

The terms axial and tangential used above are related to the central passage in the second coupling part. The first axial end of the locking segment is thereby the end of the locking segment in the direction parallel to the axial direction of the central passage.

The tangential pivot axis is here parallel to the tangential direction of the central passage, i.e. both

perpendicular of the axial direction of the central passage and perpendicular of the radial direction of the central passage .

In a preferred embodiment of the ball joint coupling according to the invention the socket-shaped surface part of a locking segment lies adjacently of a second axial end of the locking segment, which lies opposite the first axial end on which the hinge is arranged.

Providing the socket-shaped surface part as far from the hinge as possible makes it possible to obtain a maximum opening stroke between the first position and the second position, which simplifies coupling of the first coupling part to the second coupling part.

In a further embodiment of the ball joint coupling according to the invention, the hinge of each locking segment is arranged on the outer periphery of the base part. Arranging the hinge on the outer side of the base part reduces the chance of slurry running out of the dredging line and over the hinges during uncoupling and coupling of the ball joint coupling according to the invention.

In a further preferred embodiment of the ball joint coupling according to the invention the hinge of each locking segment is a pin hinge. A pin hinge is a closed hinge

construction, wherein at least two mutually engaging

cylindrical bushings are coupled to a hinge pin. During the hinging no spaces are created or reduced, whereby the hinge cannot be blocked by dirt or fouling. In another embodiment of the ball joint coupling according to the invention a first protrusion and a second protrusion are arranged at a mutual distance on each locking segment, wherein the first protrusion protrudes radially into the path of the axial displacement of the blocking ring and wherein the second protrusion protrudes at least in the second position of the locking segments radially into the path of the axial displacement of the blocking ring.

This first and second protrusion enable the locking segments to be pivoted between the first position and the second position by axial displacement of the blocking ring.

The movement of all locking segments is thus coupled in a simple and robust manner. All locking segments will hereby be moved to the second position when the blocking ring is slid to the release position, and all locking segments will be moved to the first position when the blocking ring is slid to the blocking position.

In the blocking position the blocking ring preferably lies on the outer ends of the second protrusions.

In the case of an axial force between the first coupling part and the second coupling part the locking means will hereby exert a radial force on the blocking ring, and the blocking ring will remain in the blocking position without additional measures .

In a further embodiment of the ball joint coupling according to the invention the first and second protrusions each comprise a sliding surface for contact with the blocking ring, wherein the normal of each sliding surface crosses the tangential pivot axis of the relevant locking segment.

Because the normal of each sliding surface crosses the tangential pivot axis, and so is neither parallel nor intersecting, a force exerted by the blocking ring on the sliding surfaces will result in a rotation of the relevant locking segment around the tangential pivot axis.

In yet another embodiment of the ball joint coupling according to the invention a number of actuators, such as a bellows, are arranged distributed over the periphery of the base part between the blocking ring and the base part for the purpose of axially displacing the blocking ring.

Spring means are further arranged between the blocking ring and the base part, which spring means urge the blocking ring to the blocking position.

The blocking ring can be slid from the one position to the other position in simple manner with the bellows by applying compressed air. By further arranging springs in the bellows which slide the blocking ring to the blocking position the springs urge the blocking ring to the blocking position when the bellows are not being powered. These springs are then also protected from the elements by the bellows.

Yet another embodiment of the ball joint coupling according to the invention comprises locking means for locking the blocking ring in the blocking position.

Despite the blocking ring enclosing the locking segments in the blocking position, whereby the first and second coupling part cannot be uncoupled and an uncoupling becomes possible only upon sliding of the blocking ring, it can be preferred to lock the blocking ring in the blocking position, so that undesired sliding of the blocking ring is prevented .

The locking means preferably comprise at least one locking hook arranged pivotally on the base part, which locking hook hooks behind the blocking ring in the blocking position .

The blocking ring can be held in the blocking position with the hook. The locking hook is optionally controllable by means of an actuator, such as a bellows, so that ending of the locking and uncoupling of the two coupling parts can be remotely controlled with a suitable compressed air control.

These and other features of the invention are further elucidated with reference to the accompanying

drawings .

Figure 1 is a perspective view of an embodiment of a ball joint coupling according to the invention.

Figure 2A is a side view of the coupling according to figure 1 in coupled state.

Figure 2B is a cross-sectional view of the coupling according to figure 1 in coupled state.

Figure 3A is a side view of the coupling according to figure 1 in uncoupled state.

Figure 3B is a cross-sectional view of the coupling according to figure 1 in uncoupled state.

Figure 1 shows a ball joint coupling 1 with a first coupling part with a central passage 2 and a ball-shaped outer surface 3. Ball joint coupling 1 further has a second coupling part with a central passage 4 (see figure 2B) arranged in a base part 5 with locking segments 6 pivotally arranged

thereon .

A blocking ring 7 which is slidable in axial

direction A is arranged around locking segments 6. In the shown coupled state blocking ring 7 encloses the locking segments 6 in that blocking ring 7 lies against the top of the second protrusions 8 which are arranged on locking segments 6. Further also arranged on locking segments 6 are first

protrusions 9 (see figure 2A) .

Figure 2A shows that each locking segment 6 is provided with two eyes 10 which, together with a bushing 11 arranged on base part 5 and a hinge pin 12, form a hinge with which each locking segment 6 is arranged on base part 5 of the second coupling part. For the sake of clarity of the figure the operating cage 15 and bellows 16, 17 have been omitted in figures 2A and 3A.

As is shown particularly clearly in figure 2B, hinge 10, 11, 12 is arranged on a first axial end of locking segment 6, while socket-shaped surface parts 13 are arranged

adjacently of the second axial end of locking segment 6. The socket-shaped surface parts 13 form together with an inner edge 14 of base part 5 a socket-shaped inner surface which corresponds with the ball-shaped outer surface 3, so that a hinged coupling is obtained. The pivot axis S of each hinge runs here in tangential direction.

Figure 1 shows an operating cage 15 which is coupled to blocking ring 7 so that blocking ring 7 can be slid via bellows 16 and 17, which are arranged between this operating cage 15 and the base part 5, in axial direction A. Bellows 16, as well as the springs (not visible in the figures) provided in bellows 16, urge operating cage 15 and thereby blocking ring 7 to the shown blocking position. Bellows 17 power the operating cage to reach the release position. Provided in bellows 17 are stop blocks (not visible in the figures) so that the end stop for the release position is defined without over-compression of bellows 17.

Figure 3A shows ball joint coupling 1 in the

uncoupled position, wherein blocking ring 7 has been slid down by controlling of bellows 17, so that locking segments 6 can pivot from the first position to the second position in order to enable removal of the first coupling part 2, 3 (see figure 3B) .

It is further shown clearly in figure 3B that blocking ring 7 runs against sliding surface 18 of first protrusion 9 of a locking segment 6, whereby locking segment 6 automatically pivots radially outward. Second protrusion 8 also has a sliding surface 19, against which blocking ring 7 will press when locking ring 7 returns to the blocking position shown in figure 1, whereby locking segments 6 will pivot radially inward.