Abstract:
The balancing device makes it easy to balance low and medium tonnage ships without needing to use high power. It comprises mainly one or several trains of moving masses mounted on a U track of which the side branches are parallel to the side walls of the ship, the central segment being perpendicular to the center line of the ship. Two drive wheels placed inside the turning points of the U enable driving of the train of moving mass. Application to low and medium tonnage ships.

Description:
SCOPE OF THE INVENTION 
     This invention relates to the domain of balancing low and medium tonnage ships such as launches, and particularly balancing in roll, in other words in list. 
     PRIOR ART AND PROBLEM THAT ARISES 
     French patent application 2 687 978 deposited by the same applicant describes a device for balancing a ship, particularly for balancing in roll, using a track along which a train of solid weights can move. With reference to FIG. 1 reproducing the system used in this document, the balancing elements are composed of two trains of series of rollers  19  rolling along a track, for example composed of two side rails  25  and  26 . A cable  4  driven by a motor  10  through a motor driven drum  9 , displaces the rollers  19  on each side of the ship. A blocking system  34  fixing the position using two jaws  37  is placed between the two series of rollers  19 , and is controlled by the cable  4 . The assembly is fixed in place by bringing the jaws  34  close into contact with a central positioning rail  30  placed longitudinally above the device. When the cable is not tight, the jaws  34  clamp the central positioning rail  30 . Two electrical lateral jacks  14  are also used on this device to tension the cable at its two ends through a pulley  5  fixed to the jack rod. Several of these devices may be mounted in parallel to each other in the compartments of the same ship, forming part of the ship deck structure. 
     It is easy to understand that when the cable is tensioned, the two clamping jaws  37  move apart from each other to release the device from the central positioning rail  30 . The set of rollers  19  can then be moved by applying tension to one or the other end of the cable  4 . If the tension is removed deliberately or accidentally by the breakage of a strand of the cable  4 , the clamping jaws  37  will automatically be blocked in contact with the central positioning rail  30 , in the closed position. 
     Furthermore, French patent application 2 802 504 deposited by the same applicant describes an improvement to this device as shown in FIG.  2 . It also comprises a set of moving lead masses  12 , together with a pair of jaws  16  at each end bearing on the side rails of a compartment. A single cable  2  pulls the train and controls loosening of the jaws  16 . 
     These ship balancing devices are adapted for high tonnage ships. Application of these devices to medium tonnage and particularly to low tonnage ships would cause a significant loss of volume inside the ship, due to their size. Furthermore, the cable winch control system and the cable tension control system are relatively sophisticated and are not necessary in low tonnage ships. Therefore, the purpose of the invention is to overcome these disadvantages by proposing another ship balancing device applicable to and adapted to low tonnage ships. 
     SUMMARY OF THE INVENTION 
     Therefore, the main purpose of the invention is a device for balancing a ship, particularly in roll, comprising: 
     a train of rolling moving masses forming the links of a chain forming a train; 
     train immobilization means; 
     a train tension and immobilization means control cable; 
     at least one motor to activate the train; and 
     means of adjusting the cable tension in order to control the immobilization means and comprising two moving pulleys to adjust the cable tension. 
     According to the invention, the moving masses are preformed so that they can wind around at least one drive wheel with teeth that engage in the corresponding complementary housings machined on the side of the moving masses, each of these moving masses rolling on at least two side rails on at least four rollers, the at least two rails forming a U track with two lateral branches each extending along a wall of the ship, and a central horizontal segment, the at least one drive wheel being located inside the turning point formed by the central segment and a first of the two side segments. 
     In a first preferred embodiment of the invention, it comprises two chain drive wheels, the second being located at the second turning point formed by the central segment and the second of the two side branches. 
     In one particular embodiment of the invention, the rails are composed of two opposite sides of a section. 
     In a first embodiment of the invention, the side branches are horizontal, in other words the U formed by the track composed of the two rails is horizontal. 
     In this case, the moving masses preferably have four wheels and the track is composed of two side rails. 
     In a second embodiment of the invention, the side branches are vertical, each of the rails is composed of a vertical compartment, in other words the U formed by the track composed of the rails is vertical. 
     Consequently in this case, the moving masses preferably have eight wheels rolling in sets of four on two inside faces of two opposite sides of the compartment. 
    
    
     LIST OF FIGURES 
     The invention and its technical characteristics will be better understood after reading the following description accompanied by several figures: 
     FIG. 1, already described, showing an exploded view of a first balancing device according to prior art; 
     FIG. 2 showing a top view of part of a second balancing device according to prior art; 
     FIG. 3, showing a first manner by which the device according to the invention may be installed in a ship; 
     FIG. 4, showing a detail of the construction of this first version of the invention; 
     FIG. 5, showing a section through the detail in FIG. 4; and 
     FIG. 6, showing a top view of a second manner in which the device according to the invention may be installed in a ship. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The device according to the invention is still based on a train system formed by individual rolling blocks each composed of a mass that moves from one side of the ship to the other. 
     FIG. 3 contains a top or bottom view, showing how the device according to the invention must be installed. It can be seen that the train of moving masses moves along a U track. This track is placed horizontally in the ship, so that the two side branches  50  of the U are parallel to and close to the edges of the ship, in other words each is in contact with an inside wall of the ship. A central segment  52  connects the two side branches  50  of the U. The angle between the two side branches  50  and the central segment  52  of the track is 90°. In order to form the corresponding turning point, there are two sprocket wheels  60 , at least one of which and preferably both are driving wheels, and around which the masses train  40  will wind when it moves from the central segment  52  to one of the two side branches  50 . 
     Movements of the train  40  are controlled using the drive wheels  60 . A tension cable  70  connects the two ends of the train  40 . Its circuit is composed of a loop that is closed and forms a U inside the circuit followed by the train  40 . The cable is tensioned at the ends of the two side branches  50  of the U by a mobile pulley  73  around which the cable  70  makes a half turn. In its inner path, the cable  70  makes the U trajectory around two inside detour wheels  74 . The mobile pulleys  73  are held in place elastically, each using a tension jack  71 , through a spring  72 . Thus, the cable is held at a given tension, depending on whether the train  40  must be immobilised or displaced. 
     Indeed, an increasing the tension in the cable  70  can loosen the train immobilisation system  40 . In this case, rotation of the drive wheels  60  enables the train  40  to move along the three parts  50  and  52  of the U. If the tension in cable  70  is released, then the train  40  can be blocked in the required position once it reaches it, by relaxation of the clamping system which returns to its natural blocking position. Details of operation of this system are described in detail in French patent application published under number 2 802 504. 
     Two systems are shown in the same ship in FIG.  3 . This is simply one example embodiment, and a single system, or more than two systems, could be installed inside the same ship. 
     FIG. 4 shows in detail of part of the path of the moving masses train, particularly around a drive wheel  60 . The drive wheel is shown with a given number of teeth  63  projecting outside the wheel. There is a toothed ring  64  on the inside of the drive wheel  60 , within which a drive pinion  62  engages with a much smaller number of teeth than in the inner ring  64 , in order to form a reduction gear. 
     The different moving masses  41  forming the train are attached to each other by a linking pin  42  around which each can pivot with respect to each other. They thus form part of a long chain that can be pulled to one side or the other. Each moving mass  41  on each side of the drive wheel  60  possesses a housing  43 , the shape of which corresponds to the shape of the teeth  63  of the drive wheel  60 , and more precisely corresponds to the movement of each tooth  63  in each cavity  43 , while the moving masses  41  pivot about the turning point around which the train passes. When the moving mass train  41  moves around the drive wheel  60 , each moving mass  41  pivots by 90° so that it can pass from one of the side branches  50  to the central horizontal segment  52 . 
     Two opposite sides of a section are used to guide each moving mass  41  during its displacements along the side branches and the horizontal segment. Four rollers  44  on each moving mass  41  roll along these two opposite sides. Thus, the sections act as rails for the moving masses train  41 . 
     FIG. 5 shows a section along line V—V in FIG. 4, and gives a better view of how these moving masses are arranged. This figure shows the rollers  44  rolling along the top of the opposite sides  51  of the section and installed free to rotate in the base of a moving mass  41 . This FIG. 5 also shows a tooth  63  of the drive area  60  that penetrates into the corresponding housing  43  of the moving mass, the drive gear  62  and the inner ring  64  of the same drive wheel  60 . 
     FIG. 6 shows a second way of installing the device according to the invention in a ship. In this case, the said devices  80  have been installed. The main difference compared with the installation described with reference to the previous figures, is that the side branches are placed vertically. It can be observed that side compartments  82  are located on the inside wall  85  of the ship&#39;s hull. Each surrounds a moving mass  81  symbolising the train of circulating moving masses. Note that in this version eight rollers are essential for support on both sides of the side compartments  82 . Note that in this installation mode, the motor drive must be slightly more powerful to take account of the weight of the moving masses  81  that have to be installed on the inside of the side compartments  82 . 
     In the two embodiments described, it is useful to be able to drive the drive wheels  60  using reversible hydraulic motors powered by a pressure generation system capable of supplying the power necessary for acceleration and starting, and for storing braking energy. The hydraulic motors can be recharged at any time by a pump. The fact that two drive wheels  60  are used means that the drive system can be made redundant if there is a deficiency of a failure in either of them.