Abstract:
The invention relates to a sports complex comprising: a floatable carrier body ( 3 ) with a playing field disposed thereon, a basin ( 4 ) which can be filled with liquid, in which basin ( 4 ) the carrier body ( 3 ) is situated, in which the carrier body ( 3 ) is displaceable with respect to the basin ( 4 ), and in which the basin ( 4 ) comprises a first basin part which is adjacent to a first side of the carrier body ( 3 ) and a second basin part which is adjacent to the opposite side of the carrier part, a filling means for filling the basin with liquid. The sports complex according to the invention is characterized by the fact that the sports complex furthermore comprises a liquid displacement means in order to create a difference in liquid pressure between the first basin part and the second basin part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of International Application No. PCT/NL2005/000500, filed Jul. 12, 2005, the contents of which is incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The invention relates to a sports complex. 
     BACKGROUND OF THE INVENTION 
     NL 1 017 102 describes a sports complex in which a floatable carrier body is arranged in a liquid basin. The carrier body is to a large extent made from a lightweight plastic, so that the carrier body has great buoyancy. A playing field is arranged on the carrier body, comprising turf. A liquid is introduced into the basin in order to displace the carrier body with the turf. As soon as sufficient water has been pumped into the basin to make the carrier body float, the carrier body with the turf can be taken to another position in the basin. The basin covers a surface area which is at least twice as large as the surface area of the carrier body. 
     A drawback of the known sports complex is the fact that displacing the carrier body in the basin leads to great resistance of the liquid. As the carrier body fits the basin relatively tightly, the liquid has to flow through the narrow space between the carrier body and the basin wall. The flow resistance in this narrow passage is high. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an improved sports complex. 
     This object s achieved by a sports complex according to the present invention. 
     With the sports complex according to the present invention, proper use is made of the high flow resistance between the basin wall and the carrier body. As only little liquid can flow between carrier body and basin wall, it is possible to create a difference in liquid pressure between a first basin part, which is situated on one side of the carrier body, and a second basin part, which is situated on the opposite side of the carrier body. Due to the difference in liquid pressure between the first and second basin part, a force is exerted on the carrier body, which can be used in order to displace a carrier body in a manner similar to a piston in a hydraulic cylinder. In order to create the difference in liquid pressure between the first basin part and the second basin part, a liquid displacement means is provided in the sports complex according to the invention. 
     The sports complex according to the present invention furthermore has the advantage that the mechanical load of the carrier body is more favourable than with the structure known from NL 1 017 102. With the known sports complex, the carrier body was subjected to tensile load, as a result of which the lightweight plastic structure had to he provided with tensioning wires to reinforce the carrier body. As the carrier body in the sports complex according to the invention is subjected to a compressive load, such a reinforcement is no longer necessary. 
     In one advantageous embodiment, the carrier body is provided with a liquid passage, which connects the first basin part and the second basin part to one another. This passage may, for example, consist of a tube which is arranged in the carrier body, which is preferably made of plastic. Inside this liquid passage, the liquid displacement means is then arranged. This liquid displacement means is preferably a pump. This pump may be designed in the form of a screw, similar to those used as, for example, bow screws on ships. 
     In an alternative embodiment, the first and second basin parts are connected to one another by a liquid line, which is preferably located outside the basin. In this case, the liquid displacement means is arranged inside this line. In this case, the liquid displacement means is likewise preferably a pump. 
     In a further alternative embodiment, the sports complex also comprises a first buffer reservoir and a second buffer reservoir. The first buffer reservoir can be brought into liquid communication with the first basin part, for example by means of a liquid line. The second buffer reservoir can be brought into liquid communication with the second basin part, for example likewise by means of a line. In this embodiment, a liquid displacement means is present in at least one of the connections between the buffer reservoir and an associated basin part. By displacing the liquid of the respective buffer reservoir to the associated basin part or vice versa, a difference in pressure is created between the first basin part and the second basin part. 
     The sports complex according to the present invention also comprises a filling means for filling the basin. In many cases, this filling means will comprise a pump for supplying liquid to the basin. In one advantageous embodiment of the sports complex according to the invention, the liquid displacement means, which also creates the difference in liquid pressure between the first basin part and the second basin part is used for this purpose. 
     In a further advantageous embodiment, the basin covers a surface area which is at least twice as large as the surf ace area of the carrier body. Preferably, in this embodiment, the basin also comprises a sealing door. This sealing door has an open and a closed position, the sealing door in its closed position creating two basin spaces which are separated from one another. This has the advantage that, prior to the sports field being played on, only that part of the basin has to be pumped out in which the carrier body is located. This considerably reduces the amount of time it takes to discharge the liquid from the basin and, prior to a subsequent displacement, to fill the basin. 
     Below, a sports complex according to the invention will be explained in more detail with reference to the attached drawing, in which non-limiting exemplary embodiments are shown. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawing: 
         FIG. 1  shows a diagrammatic top view of a football stadium according to the invention; 
         FIG. 2  shows a diagrammatic sectional view on an enlarged scale on the line II-II in  FIG. 1 ; and 
         FIG. 3  shows a diagrammatic top view of an embodiment of a carrier body according to the invention; 
         FIG. 4  shows a diagrammatic overview of an embodiment of a sports complex according to the invention; 
         FIG. 5  shows a diagrammatic overview of an alternative embodiment of a sports complex according to the invention; 
         FIG. 6  shows a diagrammatic overview of a further alternative embodiment of a sports complex according to the invention; 
         FIG. 7  shows a diagrammatic sectional view of an arrangement of a sports complex according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  diagrammatically shows the outer contours of a covered football stadium by means of dash-dotted line  1 . The stadium comprises stands, a playing field, etc. in the usual way. The playing field is on turf  2 , which, together with a layer of soil and a drainage system, is arranged on a carrier body  3  (see  FIG. 2 ). The carrier body  3  with turf  2  is accommodated in a basin  4 . The basin  4  has a length x 1  which is more than twice the length x 2  of the carrier body  3 . The carrier body  3  and the turf  2  are delimited at their edges by impact-resistant edge elements  5 . 
     The carrier body  3  substantially consists entirely of polystyrene, for example tempex, or another plastic material with similar strength properties and buoyancy. The material in this case has a specific gravity of less than 100 kg/m 3 , and in particular of less than 20 kg/m 3 . 
     The basin  4  can be pumped full of liquid, for example surface water, by means of a liquid pump  7 . Pumping is carried out up to a maximum filling level  8 . During pumping, the carrier body  3  with turf  2  will quickly start to float. Only a small amount of water is required for this, due to the high buoyancy of the carrier body  3 . Subsequently, the basin  4  can be emptied again by means of a controllable valve  12 . As a result thereof, the underside of the carrier body  3  comes to rest on the bottom of the basin  4 . 
     In the embodiment shown, the basin  4  is provided with a sealing door  14 . The door  14  can be moved between an open and a closed position by means of hydraulic cylinders. In the closed position, the door  14  divides the basin  4  into two parts. This has the advantage that only that part of the basin  4  in which the playing field is situated has to be pumped out. The other part can remain filled with water, which results in a big saving in time when the playing field has to be moved again. 
     A central section  20  of the basin  4  is covered by a covering  21 , over which the stands, etc. can be positioned. 
     The plastic carrier body material is preferably not hygroscopic, thus preventing it from becoming saturated with water from the basin  4  or from the wet turf  2 . In one variant, the carrier body is provided with an impermeable coating. 
     In  FIG. 3 , the carrier body  30  is composed of a large number of polystyrene elements  31 . The dimensions of the element  31  are, for example, 8000×1250×600 mm. This is a standard size which is commercially available. However, other dimensions are likewise possible. As can be seen, the elements  31  are connected, in particular bonded, to one another in a half-brick bond. In the longitudinal direction, tensioning wires  32  extend through the elements  31 . The tensioning wires  32  can be used during manufacture to bond the elements  31  to one another under pressure. The sides of the carrier body  30  formed in this way are delimited by angle sections  33 . The sections  33  are provided with a raised edge which serves to retain the layer of soil and turf to be arranged on the carrier body  30 . 
     Many variants are possible in addition to the embodiment shown. It is conceivable to use the invention in sports stadiums other than a football stadium. The carrier body may also be produced in one piece instead of from elements connected to one another. The carrier body can be produced in situ in a relatively simple manner. Polystyrene, for example, can be foamed in situ to form structures of the desired dimensions relatively easily and accurately. In the case of large dimensions this even has the advantage with regard to fragility. 
       FIG. 4  diagrammatically shows an embodiment of the sports D complex according to the invention. A floatable carrier body  3  is disposed in a basin  4  with liquid, this liquid preferably being water. In this example, the first basin part  104  is on the left-hand side of the carrier body in  FIG. 4 . The second basin part  204  is on the right-hand side of the carrier body  3  in  FIG. 4 . The carrier body  3  fits relatively accurately into the basin  4  in the width direction thereof and the basin is also relatively shallow. This offers the advantage that filling and emptying the basin requires relatively little time. As the carrier body in this example is made of a lightweight plastic, for example polystyrene, the carrier body has a great buoyancy so that the basin can be of shallow design. 
     As a result of this geometry, there is a high flow resistance under the carrier body and between the carrier body and the walls  4 ′and  4 ″ of the basin. Due to this high flow resistance, only little liquid will flow from the first basin part  104  to the second basin D part  204  or vice versa when there is a difference in pressure between the two basin parts  104 ,  105 . This makes it possible to maintain a differential pressure between the basin parts. This differential pressure generates a propulsive force which displaces the carrier body relative to the basin in the direction of the arrow P or P′ in  FIG. 4 . When the carrier body is displaced, the size of the basin parts  104  and  204  thus changes. 
     In the embodiment of  FIG. 4 , a liquid passage  110  is arranged in the carrier body  3 . This liquid passage contains a pump  125  which serves as a liquid displacement means. When the pump  125  pumps liquid from the second basin part  204  to the first basin part  104 , the pressure in the first basin part  104  will rise and the pressure in the second basin part  204  will fall. This leads to a resultant force in the direction of the arrow P on the carrier body  3 , which will be displaced in this direction P. 
     If required for a good circulation of the liquid, several additional passages  115 , optionally provided with a pump, may be arranged in the carrier body. 
     The pump may be designed in the form of a bow screw, similar to those used for ships. 
       FIG. 5  diagrammatically shows an alternative embodiment of the sports complex according to the invention. In this embodiment, there is a liquid line  130  which connects the two basin parts  104 ,  204  to one another and a pump  125  is arranged in the line  130 . In a manner similar to the embodiment in  FIG. 4 , this pump  125  moves liquid from the first basin part  104  to the second basin part  204  (see arrow  131 ) or vice versa (see arrow  132 ), in order to generate the differential pressure required for displacement of the carrier body  3 . 
     In the diagrammatic illustration of  FIG. 5 , the filling means for filling the basin is also shown. This filling means comprises a reservoir  150  and the lines  151  and  152 . In this example, the lines  151  and  152  are connected to the pump  152 . By using shut-off valves  161 ,  162 ,  171 ,  172 , the pump  125  can thus also be used for filling (and emptying) the reservoir. Of course, as an alternative, it is also possible to provide a separate pump for this purpose. 
       FIG. 6  diagrammatically shows a further alternative embodiment of the sports complex according to the invention. In this embodiment, the sports complex also comprises a first buffer reservoir  180 , which is connected to the first basin part  104  by means of lines  181 ,  182 . A pump  185  is installed in the lines  181 ,  182 . In addition, shut-off valves  186 ,  187  and  188  are provided and the sports complex also comprises a second buffer reservoir  190 , which is connected to the second basin part  204  by means of lines  191 ,  192 . A pump  195  is installed in the lines  191 ,  192 . In addition, shut-off valves  196 ,  197  and  198  are provided. In this exemplary embodiment, the pressure in the first reservoir can be increased by energizing the pump  185  and thus pumping liquid from the first buffer reservoir to the first reservoir  104 . To this end, the shut-off valves  186  and  187  are open, and  188  is closed. 
     By displacing the carrier body in the direction of the arrow P, liquid is forced out of the second basin part  204 . As a result of the shut-off valves  197  and  196  being closed, and shut-off valve  198  being open, this liquid is supplied to the second buffer reservoir  190 . 
     Someone skilled in the art will understand that a displacement of the carrier body  3  in the direction of the arrow P′ can be achieved by reversing the situation (i.e. energizing pump  190 , shut-off valves  186  and  187  closed and  188  open, shut-off valves  196  and  197  open, shut-off valve  198  closed). Alternatively, it is also possible to reduce the pressure in one of the basin parts  104 ,  204  in order to create the differential pressure required in order to displace the carrier body  3 . 
       FIG. 7  shows diagrammatically and in sectional view an arrangement of a sports complex according to the invention. The carrier body  3  is disposed in the basin  4 . The basin has raised concrete edges  304 . The carrier body comprises a polystyrene float  303  which contains soil  305  on which grass  306  for a sports field grows. A stand  307  is provided for spectators. 
     The various components, such as pumps and shut-off valves, are being driven by control unit  308 . In this example, pump  309  is in the control cabinet. 
     Reservoir  310  contains a supply of surface water in order to fill the basin  4  and allow the carrier body  3  to float.