Patent Publication Number: US-2013228304-A1

Title: Cooling compress for cooling a detector

Description:
In many cases, this is achieved by an external temperature-control system, for example by a cooling unit or a heating system. Here, the thermal energy is transported by means of a suitable medium, such as a fluid. 
     The solutions known hitherto in level measurement, for example in the form of concentric, double-walled pipes, through which water flows, require for complex superficial structures of housings and containers, for example elevations, connections, displays or mechanical fastening devices, an adaptation, which is technically often complex and thus cost-intensive, of the temperature-control system, to continue to ensure the necessary access to the functional elements on the surface of the device. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention, a cooling compress is provided for cooling a detector of a level measuring device during a level measurement. The cooling compress comprises a cooling body which at least partly consists of a deformable material. Furthermore, the cooling body is configured for attachment to a detector and for the through-flow of a cooling fluid. One region of the inner wall of the cooling body is configured such that it moves towards a corresponding region of the outer surface of the detector and forms a thermal contact with the corresponding region of the outer surface when the cooling compress is attached to the detector and when the cooling fluid flows through the cooling body. 
     Apart from enabling cooling, the described device can also provide heating. Thus, in the following when cooling is mentioned, it includes both the possibility of controlling the temperature at a value below the instantaneous actual value of the temperature (cooling) and controlling the temperature at a value above the instantaneous actual value of the temperature (heating). 
     Instead of detectors, the cooling compress can also be configured to cool other types of technical devices, for which a temperature control is possible over the outer surface of the housing. This applies in particular to measuring devices and sensors, but also to containers, motors, technical assemblies and similar objects. 
     Instead of being configured to cool parts of level measuring devices, the cooling compress can also be configured to cool other measuring devices which are able to measure the most varied physical quantities: 
     In the context of this invention, a cooling fluid includes a liquid or gaseous medium which can transport heat. Thus, in many cases, water, and in climatically dry and hot geographical regions suitable gases are used as cooling fluid. 
     The cooling body is used for the actual temperature control and should have the best possible contact with the housing surface. According to the invention, this is achieved by the deformability of the cooling body which can thus be adapted to the shape and nature of the frequently irregular surface structure. Therefore, in the following, when “deformable” is stated, it means the characteristic of the material to be able to adapt in form once and permanently (plastically) or repeatedly (elastically, flexibly) to an externally adjoining surface structure. Consequently, a significant increase in the thermal conductivity between housing surface and cooling body may be achieved. For example, parts of the cooling sleeve can consist of materials such as polyurethane, in particular of an elastomer. 
     According to a further aspect of the invention, the cooling compress is configured as a sleeve to be placed over the detector. In this case, the compress has a shape which, due to the all-round closed form, allows the compress to be simply subsequently fitted to the detector by being placed thereover, without complex fastening mechanisms. The shape is adapted to the shape of the detector and is hollow cylindrical, for example. 
     According to a further aspect of the invention, the cooling compress has a first layer which forms an outer wall of the cooling compress. The cooling compress also has a second layer which forms an inner wall of the cooling compress. Furthermore, an introduction opening, a discharge opening and optionally a fastening device are provided. The first layer and the second layer are joined together such that they form a cavity for receiving the cooling fluid. Access to this cavity is provided via the introduction opening and/or via the discharge opening. 
     During operation of the cooling compress, the cooling fluid is under a pressure which is greater than the pressure of the medium surrounding the cooling body. The second layer consists of a deformable thermoconducting material. The introduction of the cooling fluid increases the volume of the compress. 
     The terms “outer wall ” and “inner wall” describe the position of the walls relative to the housing surface. The introduction opening and the discharge opening allow the cooling fluid to flow through the cooling compress. In this way, heat can be transported from or to the cooling compress. 
     The fastening device serves to produce a mechanical connection between the cooling compress and the detector. 
     The elevated pressure of the cooling fluid serves to increase the contact pressure force of the cooling body on the housing surface, and thus serves to improve the thermal coupling. The increase in volume of the cooling compress due to the cooling fluid flowing into the cavity is achieved by the material characteristic of deformability, in particular of the second layer. 
     According to a further aspect of the invention, the fastening device is configured such that it holds the cooling compress on the detector when the cooling compress is placed on the detector. 
     The fastening device is used to mechanically fix the cooling compress on the detector housing. This allows the build-up of an increased contact pressure of the cooling compress on the detector surface, in that it mechanically prevents the compensating movement of the cooling compress away from the housing surface. 
     Subject to the nature and shape of the detector, the fastening device can be configured as a hook and loop fastener, a strap, a tape, a screw connection, an adhesive joint, a clasp, a hook or the like. 
     According to a further aspect of the invention, the first layer also has on the outside thereof a layer of textile fabric, Kevlar or a similar material. 
     This additional layer serves to mechanically protect the cooling compress against external mechanical influences. The robust structure of the additional layer serves to prevent the cooling compress from suffering mechanical and/or thermal damage. 
     According to a further aspect of the invention, the introduction opening and/or the discharge opening is configured as a bushing. 
     The bushing is used to mechanically stabilise these openings and allows pipes or hoses to be connected for the introduction and discharge of the cooling fluid. 
     According to a further aspect of the invention, the cooling compress has an electrically operated heating element for heating the cooling fluid. 
     In the context of this invention, the heating element denotes a device which, by the conversion of, for example, electrical energy into thermal energy, can release heat to the cooling fluid and thus heat the cooling fluid. This aspect of the invention allows a temperature control or heating to a desired temperature above the actual temperature. 
     According to a further aspect of the invention, the inner wall rests in a close-contoured manner against the housing surface, to be temperature-controlled, of the detector, when the cooling compress is attached to the detector. 
     In the context of this invention, “close-contoured” denotes the most accurately shaped adaptation as possible of the shape of the cooling body to the shape of the housing surface. This serves to maximise the directly contacting areas of cooling body and housing surface. 
     According to a further aspect of the invention, the cooling compress has recesses which are configured such that elements of the housing surface of the detector are accessible from outside. 
     In the context of the invention, “recesses” is typically understood as meaning openings or indentations which are configured such that they are bonded, welded or sealed in a similar manner on the edges of the cooling compress to prevent the escape of cooling fluid. These recesses are used for continued access particularly to elements which are located under the cooling compress, even after said cooling compress has been applied. 
     According to a further aspect of the invention, a level measuring device having a cooling compress described above and in the following is provided. 
     According to a further aspect of the invention, a level measuring device is provided, in which the inner wall of the cooling body of the cooling compress rests in a close-contoured manner against the housing surface, to be temperature-controlled, of the detector. 
     According to a further aspect of the invention, the cooling compress described above and in the following is used for cooling a housing of a measuring device. 
     According to a further aspect of the invention, the housing is a housing of a detector of a level measuring device. 
     According to a further aspect of the invention, a method for the temperature-control of a detector using a cooling compress is described. The method has the following steps:
         applying the compress;   securing the compress;   connecting the compress;   starting up the cooling circuit;   passing cooling fluid through the cooling compress, the pressure of the cooling fluid inside the cooling body being greater than the pressure of the medium surrounding the cooling body, as a result of which at least one region of the inner wall of the cooling body moves towards a corresponding region of an outer surface of the detector to form a thermal contact with the corresponding region of the outer surface of the detector, when the cooling fluid flows through the cooling body.       

     The first four steps can be considered as being optional. 
     The expression “securing the compress” is understood as meaning the mechanical fixing of the compress using the described fastening devices. The expression “connecting the compress” is understood as meaning the production of the necessary connections for the cooling fluid at the inlet opening and outlet opening of the cooling compress as well as the connection of the remaining lines for pump, the pressure regulating device and the cooling unit. If provided, this includes the production of the electrical connections for the heating element. The expression “starting up the cooling circuit” is understood as meaning the switching on of the pump and the starting up of the cooling unit. As a result, the cooling fluid flows through the cooling compress, the pump, the open-loop and closed-loop control unit and the cooling unit. 
     In the following, embodiments of the invention will be described with reference to the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  shows a measuring arrangement for level measurement in a container. 
         FIG. 2  is a schematic illustration of a detector having a cooling compress. 
         FIG. 3  shows a variant of the cooling compress as a sleeve according to an embodiment of the invention. 
         FIG. 4  is a detailed schematic illustration of the construction of a cooling compress according to an embodiment of the invention. 
         FIG. 5  shows a cooling compress with a heating element according to an embodiment of the invention. 
         FIG. 6  is a flow chart of a method for the temperature control of a detector using a cooling compress. 
         FIG. 7  shows a cooling circuit for cooling a detector using a cooling compress. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The illustrations in the drawings are schematic and are not to scale. 
     When identical reference numerals are used in the following description of the figures, they denote identical or similar elements. 
       FIG. 1  shows an arrangement for level measurement in a container  100  and is to illustrate the context of the use of level measuring devices. The container  100  has a lower access  101  and an upper access  102 , which is configured as an inflow or outflow for the liquid  103  present in the container  100 .  FIG. 1  shows by way of example two configurations of measuring devices, here as a radiometric level measuring device  112  and as an ultrasound level measuring device  110 . The radiometric level measuring device  112  comprises a detector housing  105  and a rod detector  107  which is attached to the outside of the housing of the container  100  by the fastening elements  109 . This detector is used to detect the radioactive radiation  108  emitted by one or more radioactive radiation sources  106 . These radioactive radiation sources  106  are attached to a support  104  such that the radiation passes through the medium to be measured to the detector  108 . The level  111  of the liquid in the container  100  can be calculated by measuring the amount of radiation  108  impacting the detector  107 . In particular, the housings  105  of radiometric detectors  112  necessitate a cooling procedure due to their mode of operation. 
     It should be noted that the configurations of measuring devices and detectors illustrated here merely serve as examples of a large number of measuring devices. 
       FIG. 2  shows an arrangement with a cooling compress  200  and a detector housing  201 , the cooling compress having a first layer  203 , a second layer  202  and the openings  207  for the introduction and discharge of the cooling fluid  205 . The second layer  202  forms the inner wall  204 . 
     The cooling compress  200  is constructed such that, as shown in  FIG. 2 , it only covers the partial areas of the housing  201  which actually require cooling. The nature of the configuration of the cooling compress  200  allows the temperature control of total areas, but also of partial areas of the surfaces of devices. This has the advantage that, since it is possible to be able to cool only relevant partial areas, the compress  200  can be configured in a relatively material-saving and cost-saving manner. The compress  200  can be attached to the surface of the housing  201  in different ways. In addition to the embodiments of the fastening devices described above, it is also possible to place the compress  200  over a horizontal housing surface, the dead weight of the compress  200  preventing undesirable shifts of the cooling compress  200  and allowing the build-up of a contact pressure on the housing surface. 
     During operation, the cooling fluid  205  is pumped through the cooling compress  200  via the inlet and outlet opening  207 . 
     According to an embodiment of the invention,  FIG. 3  is a schematic view of a detector housing  300  with a cooling compress  303 , configured here as a sleeve. This means that the compress  303  encircles the entire radial surface of the detector  300 . This makes it possible to place the sleeve or compress  303  over a detector, which is advantageous in terms of an easier attachment. Analogously to the preceding figures, the sleeve  303  has a first layer  301  and a second layer  302 , the second layer  302  forming a direct contact with the outer housing of the detector  300  during operation. 
     A fixed seat of the sleeve  303  on the detector housing  300  to be cooled is achieved due to the contact pressure of the sleeve  303 . On account of the deformability characteristic, the inner wall of the second layer  302  can be adapted to the surface structure of the detector housing  300  with the build-up of a contact pressure, and can achieve an optimum thermal coupling. 
       FIG. 4  shows the detailed structure of a cooling compress  400  according to an embodiment of the invention. The cooling compress  400  has a first layer  401  which is joined to a second layer  402 . Formed between the first layer  401  and the second layer  402  is a cavity  406  which is used to receive the cooling fluid  407 . It is also possible for a cavity  406  to be worked into the second layer  402  itself or for a foamed inner material of the second layer  402  to be provided which can absorb the cooling fluid  407  in the volume of the material of the second layer  402 . 
       FIG. 4  also shows an inlet opening  403  and an outlet opening  404  which allow access to the cavity  406  from outside and are used for the supply of the cooling fluid  407  to the cavity  406  and for the discharge of the cooling fluid  407  from the cavity  406 . According to an embodiment, to provide a mechanical reinforcement, the inlet opening  403  and the outlet opening  404  are each provided as a bushing  408 . The cooling agent  407  can be introduced into the compress  400  by hoses or pipes via this bushing  408 . 
     Fastening elements are also provided. In the figure, two securing straps  405  are shown, using which the cooling compress  400  can be attached to retaining elements on the housing surface. 
     The recess  410  is used for continued access to elements of the housing surface, such as mechanical fastening devices, displays, valves, connections, accesses and similar elements and thereby interfering with the cooling of the housing as little as possible. The recesses  410  are configured such that no cooling fluid  407  can escape at the edges of the recesses  410  and the geometric shape of the recesses  410  is chosen such that the housing elements concerned are easily accessible and at the same time, the recessed area is as small as possible. 
     The material of the second layer  402  can be configured plastically such that, after the first pressing procedure against the housing surface to be cooled, it allows the second layer  402  to retain this shape and to cure. This can be achieved, for example, using resin-based materials. 
     This results in a long-lasting resistant shape of the inner wall of the second layer  402 . This has the advantage that even without excess pressure of the cooling fluid  407  in the cooling compress  400 , the contact area between the cooling compress  400  and outer surface of the housing is increased and the thermal contact is improved. This implies a simplification of the cooling mechanism, since excess pressure no longer has to be built up to produce a contact pressure. 
     A corresponding method for the production of a formation of an inner wall of the second layer  402  has the following steps: applying the cooling compress  400 ; pressing the cooling compress  400  against the housing surface; securing the cooling compress  400 , curing the second layer  402 . 
     Attached to the outside of the second layer  402  is a further layer  409  which consists of a durable material, such as textile fabric, metal fabric or Kevlar. This additional layer  409  can protect the cooling sleeve  400  against mechanical influences, and also against extreme thermal influences. Furthermore, it reduces the likelihood of accidental damage to the cooling compress  400  during application or maintenance. 
     The mention of the term “cavity” here means the characteristic of the compress  400  of receiving the cooling fluid in its interior in a suitable manner and, in so doing, of increasing the volume of the compress  400  overall. 
     The cavities for the cooling fluid  407  can also be formed only when the cooling fluid  407  flows into the cooling compress  400 . In other words, if cooling fluid  407  does not flow through a cooling compress  400 , the cooling compress  400  does not necessarily have to contain a cavity  406 . Depending on the configuration of the second layer  402 , said cavity  406  can be formed only with the introduction of the cooling fluid  407  as a result of the deformable material of the second layer  402 . 
       FIG. 5  shows a cooling compress  200  with an electrically operating heating element according to an embodiment of the invention. In this embodiment, a temperature control can be carried out at a desired temperature which is higher than the actual temperature of the housing. The heating element has a heating coil  501  which is incorporated into the cooling compress  200  such that it results in the heating of the regions of the cooling compress which contact the surface of the housing. 
     A supply voltage source  503  is also shown which, together with a controller  502  and a switch  504 , forms the supply voltage circuit. The controller  502  is used to regulate and control the electrical heating power of the heating element  501 . The switch  504  is used to switch the heating element  501  on or off. 
       FIG. 6  is a flow chart of a method for the temperature control of a detector  201  using a cooling compress  200 . In step  601 , the compress  200  is positioned on the housing. In this respect, the region of the outer surface of the housing to be temperature-controlled is to be covered. In step  602 , the compress is secured on the housing, for example, by tapes, straps, hook and loop fasteners or the like. In step  603 , the compress is connected to the cooling circuit of the cooling fluid and optionally the electrical lines for the heating element  501  are also connected. In step  604 , the compress is switched on. This means that the cooling fluid starts to be pumped and optionally the circuit of the heating element is supplied with power and is switched on by switch  504 . 
     In the last step  605 , the cooling fluid flows through the cooling compress, at least one region of the second layer  402  moving towards the corresponding region of the outer surface of the detector  201  due to the increased pressure of the cooling fluid  407  and forming a thermal contact with a corresponding region of the outer surface of the detector  201 . 
     According to an embodiment of the invention,  FIG. 7  shows a cooling circuit, comprising a cooling compress  200 , a transportation system  701  for the cooling fluid  407 , a pump  702 , a cooling unit  703  and a closed-loop or open-loop control unit  704 . The transportation system  701  is used to transport the cooling fluid through the components of the cooling circuit. Typically, pipes or hoses are used here which connect the individual components of the cooling circuit. On the one hand, the controllable pump  702  ensures the transportation of the cooling fluid  407  through the cooling circuit, and on the other it produces the excess pressure of the cooling fluid  407 , required for pressing on the cooling compress. The cooling arrangement also comprises a closed-loop and open-loop control unit for controlling the pressure of the cooling fluid  407  in order to produce in the cooling compress a defined contact pressure which is as constant as possible. The closed-loop and open-loop control unit  704  produces a controlled variable  705  which is forwarded to the pump control, thereby making it possible to influence the pressure of the cooling fluid  407 . For an expedient operation of the cooling compress  200 , a pressure of the cooling fluid  407  and thereby of the contact pressure of the compress on the housing surface is produced which is as constant as possible. 
     An advantage of the invention may be that the contact area between the cooling body and the outer wall of the housing is increased due to the deformability of the cooling body. In addition, the thermal conductivity between cooling body and outer surface of the housing is improved by the contact pressure of the cooling compress on the housing. Recesses also provide the possibility of continuing to keep elements of the housing surface accessible. 
     In addition, it is pointed out that the terms “comprising ” and “having” do not exclude any other elements or steps and “a” or “an” does not exclude a plurality. It is also pointed out that features or steps which have been described with reference to one of the above embodiments can also be used combined with other features or steps of other embodiments described above. Reference numerals in the claims should not be construed as limiting.