Abstract:
A cooling system for a rotary tablet press with which a rotor is driven by an electrical drive motor and the rotor and drive motor are arranged in a closed housing, and a control cabinet for the drive motor and further units in the housing, wherein arranged within the housing is a cooling machine whose evaporator is part of a first heat exchanger, whose other part is arranged in a coolant circuit for the drive motor, a fan is arranged in a channel in the housing closed relative to the housing interior, where the fan draws cool air in via an air inlet of the housing and gives it off via an air outlet of the housing, wherein the cool air is engaged in heat exchange with a condenser of the cooling machine.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     A system for producing tablets along with the customary rotary press includes additional parts and peripheral units. The essential electrical and electronic components and components for the control of the main drive of the press and the servo drives in the press are located together in a control cabinet, which is connected to the tablet press via a cable. 
     The electrical components, in particular, the power units and the machine computer heat up during operation, and it is necessary to provide sufficient cooling in order to limit the heating. The heating of these parts, naturally, also heats up the operating area of the entire system; the lower the thermal loss in the control cabinet is kept and the more effectively the heat dissipation from the control cabinet occurs, the higher the ambient temperature can be. Thus, the availability of the entire system increases with the control of the thermal loss. 
     From DE 103 21 022 B4, the entire contents of which is incorporated herein by reference, the control cabinet for a tablet press is known that is attached to the lower portion of the press housing. A ventilation channel, whose inner wall is formed by a housing wall section, is located on the exterior of the closed control cabinet. Assigned to the ventilation channel is a fan, which feeds external air through at least one inlet into the ventilation channel, wherein the air escapes through at least one outlet. A second fan, which circulates the air in the interior of the housing, is arranged in the interior of the control cabinet housing such that the air strikes at least partially along the inner side of the housing wall that delimits the ventilation channel. 
     From DE 10 2004 040 163 A1, the entire contents of which is incorporated herein by reference, a rotary tablet press is known, in which the runner of an electrical drive motor is arranged on the rotor shaft in a torque-proof manner. The runner is arranged directly below the rotor on the rotor shaft. From the state of the art, it is further known to integrate the runner of the drive motor into the press rotor, wherein the runner surrounds the stator. Both drive arrangements have the advantage that an extraordinarily compact construction can be attained. Due to the fact that the motor is arranged relatively close to the dies in the die plate, the heat generated in the motor is also transferred onto the die plate. However, it is normally required that the die plate in the area of the dies must not exceed a maximum temperature, which is relatively low. 
     The objective of the invention is to create a cooling system for a rotary tablet press, which enables an effective cooling also for an electrical drive motor mounted near the rotor. 
     BRIEF SUMMARY OF THE INVENTION 
     With the cooling system according to the invention, within the housing, a refrigerating unit is arranged, whose evaporator is a part of a first heat exchanger, whose other part is arranged in a coolant circuit for the drive motor. In a channel within the housing, a fan is arranged which draws in cooling air via an air intake and gives off the air via an air outlet in the housing, wherein the cooling air is engaged in heat exchange with the condenser of the refrigerating unit. 
     Using the measure according to the invention, the heat from the drive motor can be removed effectively, so that an undesired heating of the die plate does not occur. The invention enables cooling by means that are arranged in the interior of the housing. Fans attached to the exterior or flange-mounted cooling units are not necessary. 
     According to an embodiment of the invention, water is provided as a coolant in the cooling circuit. 
     According to another embodiment of the invention, the intake is arranged in the bottom of the housing, and the air outlet is arranged in the top of the housing. These openings preferably lie near a side wall of the housing. 
     The cooling system according to the invention is especially advantageous with a drive motor integrated in the rotor, where the runner is connected to the rotor in a torque proof manner, and the stator lies in the interior of the runner. The coolant lines can then be simply connected to the cooling system in the stator of the electric motor. 
     The condenser of the refrigerating unit for the cooling system according to the invention is cooled with room air. Therefore, an embodiment of the invention provides that the condenser/heat exchanger is arranged in the upper region of the housing, and the fan is arranged on the up-stream side of the condenser/heat exchanger. Thus, the refrigerating unit is arranged in relatively elongated arrangement near a side wall of the housing, and therefore, is housed in a space-saving manner. 
     According to a further embodiment of the invention, the channel areas through which room air passes, preferably have a so-called nano-coating. This prevents the deposition of impurities on the channel walls, so that cleaning measures or similar can be eliminated. 
     According to a further embodiment of the invention, a second heat exchanger, through which the coolant flows, is arranged in the housing, and a second fan generates a cool air stream across the second heat exchanger, which e.g., is directed into the housing, in order to sufficiently cool the housing atmosphere and with it the parts of the tablet press. It is also conceivable to attach the second heat exchanger to the wall of a control cabinet outside of the press housing, wherein naturally, the coolant lines must be led to the outside as well. 
     According to the invention, it is especially advantageous if the control cabinet is also arranged below the rotor in the housing. Because according to the invention, the drive motor is arranged closely below the rotor or in the rotor itself, sufficient space is available for the placement of the control cabinet at the lower end of the housing. Because the control cabinet and also the parts held by it are to be cooled, according to an embodiment of the invention, the cool air stream of the second fan flows through the inside of the control cabinet. 
     According to a further embodiment of the invention, the rotor with the drive can be arranged within a process housing, closed relative to the housing, into which and out of which the coolant lines are led. 
     Finally, according to a further embodiment of the invention the refrigerating unit can be assigned a temperature control device, which is connected to a temperature sensor in or on the rotor, and/or a sensor in the housing. Thus, the heat in the rotary press can be controlled and led away in a controlled manner. The cooling system is integrated into the tablet press and does not require any external devices, or fans attached to the housing, flange-mounted devices, or similar. If placed on the bottom and the top of the housing, the air openings remain out of sight. 
     With the invention, a heating of the die plate is prevented wherein the temperature ranges can be adjusted via the user interface at an operator computer. The cool air for the refrigerating unit is separated from the air within the housing. The cooling of the drive motor and with it also the cooling of the die plate on the one hand, and the process space on the other, occurs with the coolant of the same circuit. The temperature of the coolant can be preselected, as mentioned, by control of the refrigerating unit. The heat dissipation occurs via a heat exchanger to the ambient air. 
     It is advantageous with the cooling system according to the invention that the waste heat is ready in condensed form for leading off, and is at a low entropy level. Because additional devices are not needed, no additional connection lines are necessary, whereby minimal space is required. Nonetheless, the possibility exists to service and clean the parts of the cooling system according to the invention via maintenance openings in the housing. 
     When a tablet press is mentioned in the preceding and below, it refers to general rotary presses for producing preforms from powdered material. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE INVENTION 
       An exemplary embodiment of the invention is explained in the following in more detail using the drawings. 
         FIG. 1  schematically shows the layout of a cooling system according to the invention in the housing of a tablet press. 
         FIG. 2  shows the block circuit diagram of the cooling system according to  FIG. 1 . 
         FIG. 3  shows a schematic section of a round runner tablet press with a drive; 
         FIG. 4  shows another embodiment of a drive in a round runner tablet press. 
         FIG. 5  shows yet another embodiment of a drive in a round runner tablet press. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated 
     A cuboid housing  10  for a rotary tablet press is indicated in  FIG. 1 . It rests on feet  12  and thus, is somewhat above the ground. In the housing  10 , a rotor  14  with die plate  16  of a rotary press, not represented further, is indicated that is mounted in a suitable machine frame (not shown). Parts of the rotor project above and below of a process housing  18 , which houses the process space of the press, so that production dust does not reach the outside. It is understood that an appropriate sealing is provided above and below. 
     The drive motor is integrated in the rotor  14 , as is disclosed in DE 10 2004 040 163 A1. The stator of the motor also projects above and below of the process housing  18 . 
     A control cabinet  20 , arranged on the bottom of the housing  10 , contains all electrical and electronic components including a machine computer for the operation of the double rotary press. These parts are known and therefore, should not be further listed. 
     A refrigerating unit is housed in an elongated housing  22 , extending from the bottom to the top of the housing  10 . It has an evaporator  24 , a compressor  26 , a condenser  28  and an air regulator  30 . These are the customary parts of a compression refrigerant circuit, as it is generally known. The evaporator  24  is part of a heat exchanger, whose other part  34  forms section of a coolant circuit. The coolant circuit is composed of a cooling system of the stator of the motor, not shown, which is connected via the lines  36  and  38  to the heat exchanger part  34  and a further heat exchanger  40 . The heat exchanger  40  is attached to the outer wall of the control cabinet  20 , where it is assigned a fan  42 . 
     A further fan  44 , located in the housing  22 , draws in air through a lower inlet  48  via a channel  46 . The channel  46  is formed between the housing  22  and the associated housing wall. The air flow  50  drawn in by the fan  44  reaches an upper outlet  52  via the condenser  28  of the refrigerating unit. Consequently, the cooling of the condenser  28  occurs by means of room air. 
     The cooling of the drive motor (not shown) and the die plate  16  occurs with a coolant, which is preferably water, in the described coolant circuit. The coolant flows—possibly supported by a pump—through the heat exchanger  40 , and the fan  42  generates an air flow  56  within the housing  10 , which air flow is also cooled by the heat exchanger  40 , and therefore, cools the atmosphere in the housing  10  and with it the process housing  18 . 
     In the block diagram according to  FIG. 2 , the same parts as already shown in  FIG. 1 , are provided with the same reference numbers. Additionally represented are the drive motors  60 ,  62 , and  64 , for the compressor  26 , and the fans  44  and  42 . They are controlled by a controller  66 , which is connected to sensors  68  and  70 . The sensor  68  measures the temperature in the area of the die plate  16  and within the rotor  14 . The sensor  70  measures the temperature within the housing  10  or the process housing  18 . The controller  66  is connected to an operator computer, not shown, for example, via a radio link. In a suitable manner, a set-point for the temperature of the die plate or in the housings  10  and  18  is preset in the controller  66 . Through a suitable control of the refrigerating unit and the fans  42 ,  44  it is ensured that the set temperature is reached and held. 
       FIG. 3  a machine frame is labeled with  110 . It is used to carry a rotary press for making tablets. The latter exhibits a rotor  112 , which, as usual, consists of a die plate  114 , upper guide  116  for punches and lower guide  118  for punches. The named parts form a unit. The guides  116 ,  118  take upper punches  120  or lower punches  122 , respectively, and guide these axially. They work together with non-labeled dies of die plate  114 . The control of the upper and the lower punches  120 ,  122  is carried out by cam segments  124  or  126 , respectively. Furthermore, an upper pressure roller  128  and a lower pressure roller  130  can be seen which are used to compress the powder material in the die by pressing upper and lower punches  120 ,  122  towards each other. As can be seen, the upper cam segments  124  are carried by an upper traverse  134  of frame  110  by means of respective retaining means  132 . A bearing part  136  for the upper pressure roller  128  is also mounted to the traverse  134 . The lower cam segments  126  are mounted in a lower traverse  138  of frame  110 , to which traverse also a retaining portion  140  for the lower pressure roller  130  is fixed. The lower traverse  138  also bears the rotor shaft  142 , namely by a lower antifriction bearing  144  and an upper antifriction bearing  146 . The rotor shaft  142  is coupled with the rotor  112  in a suitable way not shown. 
     An electric drive motor  148 , for instance a so-called torque motor, is fixed to the rotor shaft  142  below the traverse  138 . Its runner  150  is placed on a lower, dashed segment of rotor shaft  142  in a torque proof manner. The runner  150  rotates in the stator  152  by means of an upper antifriction bearing  159  and a lower antifriction bearing  156 . The torque at stator  152  is absorbed by means of a torque plate  157 . 
     As far as the same parts are taken in the embodiment according to  FIG. 4  as in the embodiment according to  FIG. 3 , the same labels are used. The embodiment according to  FIG. 4  is distinguished from that according to  FIG. 3  in that the rotor shaft  142   a  is significantly shorter and below the rotor shaft  142   a , a free space remains in frame  110   a . The electric drive motor  148   a  is placed immediately below the rotor  112 , and the runner  150   a  seats on a section of the rotor shaft  142   a  with reduced diameter. One sees that in this embodiment the achievable saving of space is considerable. The remainder of the parts of the embodiment according to  FIG. 4  are composed and mounted similarly as it has been described in connection with  FIG. 3 . 
     In the embodiment according to  FIG. 5 , again the same parts are labeled with the same labels as in the embodiments according to  FIGS. 3 and 4 . 
     The embodiment according to  FIG. 5  is distinguished from those according to  FIGS. 3 and 4  in that on the traverse  138   b  of the frame  110   b , a vertical supporting post is disposed in a stationary manner. The post exhibits a section with reduced diameter at an upper end which is labeled with  156 , and it is disposed on the stator  152   b  of an electric drive motor  148   b  in a stationary manner, while its runner  150   b  is integrated in the rotor  112   b . For mounting of the runner  150   b , the rotor  112   b  can be divided in a horizontal plane or, alternatively, it can be composed of two or more segments in circumferential direction, which are combinable fittingly and firmly, but detachably. The rotor  112   b  is supported rotatably on the supporting post  159  by means of an upper antifriction bearing  160  and a lower antifriction bearing  162 . As can be seen, the upper cam segments  124   b  are also fixed to the upper end of the supporting post  159 . The lower pressure roller  130  is, on the one hand, supported in the bearing element  140 , which is mounted on the traverse  138   b , and on the other hand it is supported at the supporting post  159 . 
     In the embodiment according to  FIG. 5 , one can see the large economy of space which is achieved in this construction. 
     The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims. 
     Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim  1  should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below. 
     This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.