CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of International Application No. PCT/EP2009/007689, filed on Oct. 28, 2009, which claims the priority of German Patent Application No. 10 2008 057 752.9, filed on Nov. 17, 2008. The contents of both applications are hereby incorporated by reference in their entirety. 
     FIELD OF INVENTION 
     The invention relates to a filling device for filling containers with hot liquid. 
     BACKGROUND 
     To achieve hot, sterile filling, it is often necessary to fill products at a high product temperature. These product temperatures can be as high as 90 and 95° C. 
     A problem that can arise with this type of hot filling process or with the filling devices that are used for this hot filling is that the filling devices that are used for the controlled filling of the product must already be at the elevated product temperature before the filling process is commenced. Otherwise, the content that is to be introduced to the filling devices may cool down in an undesirable manner during the filling process. To avoid this, it is known to pre-heat filling devices prior to starting the filling process. 
     In a similar way, in the event of any interruptions to a filling process, both the content and the filling devices must be maintained within the required temperature range so that the filling process can be restarted immediately using filling devices that are at the correct temperature. 
     Filling systems or filling machines for resolving these problems are already known. In these known devices, the filling devices are drawn into a heating device by conducting a partial current of the hot content through the filling device in a closed circulation that has a heating device. This heats the contents and/or maintains them at the respective required temperature. 
     A negative aspect of these known filling systems or filling machines is, among other things, the need for exceptionally costly, delicate, and high-priced ventilation arrangements. 
     SUMMARY 
     The task of the invention is to present a filling device, that can be heated with a simplified design in circulation path of the hot liquid. 
     A special advantage of the invention arises from the fact that both the liquid valve of the respective filling device and addition the flow channel that has been designed for the hot circulation are controlled solely by the movement of the particular container that is to be filled. Thus, when the container is connected to and/or pressed onto the filling device, the liquid valve is opened and the flow path for the hot circulation is thereby closed or restricted and reversed. When the filled container is removed from the filling device, the liquid valve is closed, and the flow path for the hot circulation is fully opened. 
     Further modifications, advantages and possible applications of the invention also result from the following description of examples of the design and from the illustrations. In this, all of the characteristics described and/or presented in illustrated form are basically the object of the invention either on their own or in any combination, regardless of their summarization in the claims or of their retroactive application. Also the content of the claims is made as an integral part of the description. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The invention is explained here-below in greater detail by means of illustrations of an example of the design in which 
         FIG. 1  shows a rotating filling machine with the filling device closed, together with a bottle lowered relative to the filling device; 
         FIG. 2  shows the filling position of  FIG. 1  with the bottle raised against the filling device and ready to be filled; 
         FIGS. 3 and 4  show enlarged views of the closed and opened liquid valves of  FIGS. 1 and 2 ; and 
         FIG. 5  shows a cross section of the casing parts of the two-piece filling device casing along the line I-I of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a filling device  1  of a rotating filling machine for the non-pressurized filling of containers in the form of bottles  2  with hot liquid contents. By way of an example, the hot liquid contents are at a temperature of between about 90 and 95° C. 
     The filling device  1  is installed, together with a large number of similar filling devices  1  of a similar design, on the periphery of a drivable rotor  3  that rotates around a vertical machine axis. This has, among other things, a common boiler  4  for all of the filling devices. One example of a boiler  4  is a ring-type boiler. The boiler  4  is partly filled with the hot liquid contents. The level of hot liquid in the boiler  4  is controlled to be at the level N. As a result, within the inner chamber of the boiler  4 , there is a lower liquid chamber  4 . 1  and a gas chamber  4 . 2  above it. Hot liquid content flows into the lower liquid chamber  4 . 1 , while inert gas fills the gas chamber  4 . 2 . 
     Each filling device  1  has a filling device casing  5  fixed on the base of the boiler  4 . Each filling device casing  5  has two pieces: a first casing part  5 . 1  and a second casing part  5 . 2 . The first casing part  5 . 1  is fixed to the rotor  3  or to the base of the boiler  4 . The second casing part  5 . 2  is positioned vertically in relation to the first casing part  5 . 1 . 
     The second casing part  5 . 2  is movable in the direction of a filling-device axis FA between a lower lift position and an upper lift position. The lower lift position is shown in  FIG. 1  or  3 , and the higher lift position is shown in  FIG. 2  or  4 . 
     A compression spring  6  acting between the first and second casing parts  5 . 1 ,  5 . 2  pre-stresses the second casing part  5 . 2  into the lower lift position. This compression spring  6  is fitted in the side of the casing and concentrically encloses the filling-device axis FA. 
     The second casing part  5 . 2  includes a valve plate  7  that is perpendicular to the filling-device axis FA. The compression spring  6  abuts against a top side of this valve plate  7 . 
     A filler pipe  8  that is open at both ends passes through the valve plate  7  in a sealed manner and penetrates into the first casing part  5 . 1  with its upper filler pipe section  8 . 1 . A lower filler pipe section  8 . 2  of filler pipe  8  projects below the base of the valve plate  7  and forms a delivery opening at its lower end. A liquid valve  9  at this lower end controls filling of the bottles  2  with the liquid content. The operation of the valve  9  will be described in more detail below. 
     In the illustrated embodiment, the liquid valve  9  is a foot valve having a valve body  10  at a lower projecting end of a gas return pipe  11 . The gas return pipe  11  is arranged on the same axis as the filling-device axis FA and works in conjunction with a valve body surface. A seal  12  is formed from the lower edge of the opening of the lower filler pipe section  8 . 2 . 
     The gas return pipe  11  extends through the valve casing  5  and, in a sealed manner, through the liquid chamber  4 . 1  of the boiler into the adjacent gas chamber  4 . 2 . In doing so, the gas return pipe  11  defines a gas return channel  13 . In the version of the design, the gas return channel  13  remains constantly open at the base of the filling device  1 , i.e. in the valve body  10  and also on the end of the pipe that extends into the gas chamber  4 . 2 . 
     A first annular channel  14  is formed within the filler pipe  8  between its inner surface and an outer surface of the gas return pipe  11 . This first annular channel  14  discharges into a channel  15  in the first casing part  5 . 1  that is formed at the top end of the filler pipe  8 . This channel  15  connects to the liquid chamber  4 . 1  of the boiler  4  at the base of the boiler  4 . 
     The channel  15  has an annular channel section  16  that concentrically encloses the filling-device axis FA. This annular channel section  16  is formed between the outer surface of the upper filler pipe section  8 . 1  and the inner surface of the casing part  5 . 1 . In particular, the annular channel section  16  is bounded by an inner surface of a tube-like casing section  5 . 1 . 1  of the casing part  5 . 1  that encloses the upper filler pipe section  8 . 1 . A clearance between the upper filler pipe section  8 . 1  and the inner surface  5 . 1 . 1  defines the width of the annular channel section  16 . 
     Just above the valve plate  7 , the tube-like casing section  5 . 1 . 1  has a lower annular opening  17  that surrounds the filling-device axis FA. The annular channel section  16  extends downwards to this lower annular opening  17 . The annular opening  17  opens into a second annular channel  18  that encloses the casing section  5 . 1 . 1 . The outer wall of this second annular channel  18  is a cladding that enables the second casing part  5 . 2  to move relative to the first casing part  5 . 1 . As a result, the casing  5  can be axially shortened and lengthened in the direction of the filling-device axis FA. In the illustrated embodiment, the cladding is in the form of bellows  19 . 
     The second annular channel  18  is connected to a third annular channel  20  on the top end that is located furthest away from the annular opening  17 . The third annular channel  20  is provided in or on the rotor  3  and serves all of the filling devices  1  of the rotating filling machine. In the alternative, the third annular channel  20  serves a group of such filling devices. 
     A seal  21  is fitted around the lower filler pipe section  8 . 2  as it projects below the valve plate  7 . The seal  21  abuts against the base of the valve plate  7  via a spacer  22 . Below this seal  21 , a filler pipe part length  8 . 2 . 1  of the lower filler pipe section  8 . 2  projects further downward. 
     A container support  23  is allocated to each filling device  1  of the rotating filling machine. As shown in  FIG. 3 , the container support  23  suspends a bottle  2  on a flare  2 . 2  that extends radially outward from the bottle just below a bottle mouth  2 . 1 . A spring, which is not shown, biases the container support  23  into a raised lift position. 
     A guiding rod  24  guides the container support  23  onto the rotor  3  along the filling-device axis FA. This enables the container support  23  to be moved between a lowered lift position, shown in  FIG. 1 , and the raised lift position, shown in  FIG. 2 . A cam roller  25  controls the transition between these two lift positions. The cam roller  25  operates in conjunction with a control cam  26  that is not circumferential with the rotor  3 . The container support  23  and its related filling device  1  together define a filling position  27 . 
     A containers or bottles  2  is guided to a filling positions  27  with the container support  23  lowered. The bottle mouth  2 . 1  is positioned directly below the respective filling device  1  with clearance between the filling device  1  and the mouth  2 . 1 . The container support  23 , together with the bottle  2  that it suspends, is then raised until the bottle mouth  2 . 1  is against the seal  21 . 
     The raised container support  23  overcomes the force of the spring  6  and thus moves the second casing part  5 . 2  upwards into the higher lift position. This opens the liquid valve  9 . As a result, liquid content flows from the boiler  4  via a liquid channel formed by the channel  15  and the first annular channel  14  and the opened liquid valve  9 , and enters the bottle  2 . As liquid content enters the bottle, it forces compressed air is channeled from the bottle  2  through the gas return channel  13 . 
     Eventually, the rising level of the content in the bottle  2  reaches the lower end of the gas return pipe  11  that has been inserted into the bottle  2 . Immersion of this end into the liquid content closes the gas return channel  13  and automatically stops the filling. The filling level in the filled bottles  2  is determined by the filler pipe part length  8 . 2 . 1 . This can be adjusted using spacers  22  with differing axial extents. When the container support  23  is lowered, taking the filled bottle  2  with it, the second casing part  5 . 2  is also lowered. This closes the liquid valve  9 . 
     The filling level of the content in the respective bottles is thus determined by the length with which the lower filler pipe section  8 . 1  projects beyond the seal  21  and thereby, during the filling process, extends into the interior of the bottle  2  through the mouth of the bottle  2 . 1 . 
     The lower lift position of the second casing part  5 . 2  is defined by the fact that the lower filler pipe section  8 . 2  is positioned with its lower edge against the body of the valve  10  or of its seal  12 . The upper lift position of the second casing part  5 . 2  is defined by the fact that the valve plate  7  is positioned against the lower edge of the casing section  5 . 1 . 1 . 
     A characteristic of the filling device  1  arises from the fact that it is possible to heat the filling device  1  by circulating hot liquid content from the boiler  4 , through the filling device  1 , and back to the boiler  4 . In particular, for each filling device, hot liquid content circulates from the liquid chamber  4 . 2 , through the channel  15 , through the annular channel section  16 , and the annular channel, into the third annular channel  20  and, from there, via a product pump  28  and a heating device  29  back, into the liquid chamber  4 . 1  of the boiler  4 . 
     The foregoing circulation provides effective heating of the filling devices  1 . As a result, the filling devices  1  can be pre-heated to the required raised product temperature, and can be maintained at the requisite desired temperature in the event of an interruption of the filling process. Because the circulation continues even when not filling, any hot content in the filling device does not remain there long enough to cool down. Thus, the filling devices  1  does not cool down, and filling can be started immediately without having to wait for the filling device  1  to heat back up. This permits prompt resumption of the filling process after an interruption. 
     A further characteristic arises from the fact that raising and lowering of the bottle  2  not only controls opening and closing of the liquid valve  9 , but also controls the hot circulation through the filling device  1 . 
     As a comparison of  FIGS. 3 and 4  shows, the annular opening  17  for the hot circulation or for the flow-through of the annular channel section  16  and of the second annular channel  18  with the hot content is fully opened when the second casing part  5 . 2  in the lower lift position and the liquid valve  9  is closed. 
     Raising the second casing part  5 . 2  opens the liquid valve  9  and at the same time makes the annular opening becomes increasingly smaller. This reduces the effective flow cross-section of the flow path formed by the annular channel section  16  and the second annular channel  18 . Eventually, the valve plate  7  reaches the lower edge of the casing section  5 . 1 . 1 . This not only ends the upward lifting movement of the second casing part  5 . 2  but also completely closes the annular opening  17 . 
     Closing the annular opening  17  interrupts the circulation loop. As a result, all of the liquid content that enters the filling device  1  enters the container through the liquid valve  9 . None of it is diverted into a circulation loop. This results in the shortest possible filling time and thereby yields the highest possible output from the rotating filling machine (i.e. the number of filled bottles per unit of time. 
     In contrast, closing the liquid valve  9  is closed before and after the respective filling phase fully opens the annular opening  17  for the hot circulation. 
     The resulting filling device  1  has an exceptionally simple design. Yet, it manages to block and unblock the circulation loop as needed. All that is required to trigger this blocking and unblocking of the circulation loop is the raising and lowering of a bottle at the liquid valve  9 . 
       FIG. 5  shows fins  30  projecting radially from the inner surface of the casing part  5 . 1  and of the tube-like casing section  5 . 1 . 1 . These fins  30  extend to the outer surface of the upper filler pipe section  8 . 1 . Thanks to these fins  30 , there is a significant enlargement of the surface area that is in contact with the hot liquid content that flows through the annular channel section  16 . This results in faster heat exchange. 
     Furthermore, the fins  30  cause a certain turbulence of the flow of the content. This also improves the release of heat transfer from the hot liquid content to the casing  5 . 
     Having the hot liquid content follow a long path through the filling device  1  during circulation further enhances heat transfer. In the illustrated embodiment, the hot liquid content follows a twisted path through the filling device  1 , thus providing many opportunities for heat exchange. Yet, the filling device  1  as a whole remains compact. 
     The invention has been described above using one example of the design. It should be understood that changes and variations are possible without thereby departing from original concepts of the design. 
     LIST OF DRAWING REFERENCES 
     
         
         
           
               1  Filling device 
               2  Support or bottle 
               2 . 1  Bottle mouth 
               2 . 2  Flange of the mouth 
               3  Rotor 
               4  Boiler 
               4 . 1  Liquid chamber of the boiler  4   
               4 . 2  Gas chamber of the boiler  4   
               5  Filling device casing 
               5 . 1 ,  5 . 2  First and second casing parts 
               5 . 1 . 1  Casing section 
               6  Spring 
               7  Valve plate 
               8  Filler pipe 
               8 . 1 ,  8 . 2  Upper and lower filler pipe sections 
               8 . 2 . 1  Filler pipe part length 
               9  Liquid valve 
               10  Valve body 
               11  Gas return pipe 
               12  Seal 
               13  Gas return channel 
               14  First annular channel 
               15  Channel 
               15 . 1  Opening 
               16  Annular channel section 
               17  Annular opening 
               18  Second annular channel 
               19  Movable cladding or bellows 
               20  Third annular channel 
               21  Seal 
               22  Spacer 
               23  Container support 
               24  Guide rod 
               25  Cam roller 
               26  Control cam 
               27  Filling position 
               28  Product pump 
               29  Heating device 
             FA Filling-device axis 
             N Level
A filling element for filling systems for filling bottles or similar containers ( 2) with a hot liquid product, comprising a liquid channel ( 14, 15), which is formed in the filling element ( 1), has a filling valve ( 9) and forms at least one discharge opening, via which, by controlled opening and closing of the liquid valve ( 9), the liquid product can be introduced into the respective container ( 2) that has been raised towards the filling element ( 1) in a lifting movement, and comprising at least one flow path ( 16, 17, 18), which is formed in the liquid valve ( 1) and, for heating the filling element ( 1), can be connected to a hot circulation of the liquid product, characterized in that control means ( 5.2) are provided and, by the lifting movement of the container ( 2) to be filled, open the liquid valve ( 9) and block the flow path ( 16, 17, 18) for the hot circulation or reduce the effective flow cross section of this flow path ( 16, 17, 18), and in that optionally, at least over part of the length of the flow path ( 16, 17, 18) for the hot circulation, the inner surface of this flow path is profiled, for example provided with ribs ( 30), to increase the surface area that comes into contact with the product and/or to create a turbulent flow of the product.