Patent Publication Number: US-2021190599-A1

Title: Housing element for securing at least one temperature sensor on a measuring object

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of the filing date under 35 U.S.C. § 119(a)-(d) of European Patent Application No. 19217288.0, filed on Dec. 18, 2019. 
     FIELD OF THE INVENTION 
     The present invention relates to a housing element and, more particularly, to a housing element for securing at least one temperature sensor on a measuring object. 
     BACKGROUND 
     In the operation of a temperature sensor, it is desired to keep the sensor in close physical contact with the measuring object. This contact should not be impaired by vibrations or other disturbances. When the position of a temperature sensor and/or the heat transfer between the temperature sensor and the measured object is impaired, the measuring object may overheat without being noticed. In the worst case, failure of the object may occur. 
     SUMMARY 
     A housing element for securing a temperature sensor on a measuring object includes a filling and a sheath surrounding at least a portion of the filling. The filling forming a sensor cavity housing the temperature sensor and an insertion channel receiving the measuring object. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example with reference to the accompanying Figures, of which: 
         FIG. 1  is a perspective view of an arrangement according to an embodiment and a temperature sensor; 
         FIG. 2  is a schematic end view of the arrangement prior to shaping; and 
         FIG. 3  is a schematic perspective view of the arrangement after shaping. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     In the following, the invention and its improvements are described in greater detail using exemplary embodiments and with reference to the drawings. The various features shown in the embodiments may be used independently of each other in specific applications. In the figures, elements having the same function and/or the same structure will be referenced by the same reference signs. 
     An arrangement  1  according to an embodiment, as shown in  FIG. 1 , comprises a housing element  3  and a temperature sensor  5 . The temperature sensor  5  without the housing element  3  is also shown below the arrangement  1  in  FIG. 1 . The temperature sensor  5  may be any appropriate temperature sensor, for example a NTC-sensor (Negative Temperature Coefficient) or another resistive element, such as a Platinum sensor (e.g. Pt100 or Pt1000) or a thermocouple utilizing the thermoelectric effect. 
     The housing element  3 , as shown in  FIG. 1 , has an overall longitudinal shape and extends along a longitudinal direction L. The temperature sensor  5  is embedded in the housing element  3 , in particular in a sensor cavity. Electric conductors  7  extend basically parallel with the longitudinal direction away from the housing element  3  in order to establish an electrical contact with the temperature sensor  5 . The housing element  3  may serve as a securing element for the temperature sensor  5 . 
     The housing element  3  is provided with an insertion channel  9  for receiving a measuring object  11  at least in parts, as shown in  FIG. 1 . In an embodiment, the measuring object  11  is a part of an electric drive. However, the housing element  3  may also be used for other purposes. The measuring object  11  may in particular be a temperature lance that is adapted for transferring heat from a heat source of the object to the temperature sensor  5  inside the housing element  3 . 
     The insertion channel  9  has an overall longitudinal, in particular cylindrical, shape. The insertion channel  9  opens up to an object end  13  of the housing element  3 , whereas the temperature sensor  5  is accessible via its electric conductors  7  from a sensor end  15 . The object end  13  and the sensor end  15  are arranged opposite each other along the longitudinal direction L. The insertion channel  9  may be formed as a shaft, tunnel or a blind hole, having a constant inner diameter and being closed at one end. In another embodiment, the insertion channel  9  may have a non-constant inner diameter and/or may be formed as a through-hole. 
     In an embodiment, the sensor cavity  23  and the at least one insertion channel  9  open up to opposite sides  13 ,  15  of the housing element  3 . Thereby, the cable routing for the temperature sensor  5  may be improved because cables may be guided away from the measuring object  11 , without colliding with the measuring object  11 . 
     The housing element  3  is composed of a filling and a sheath  17 , shown in  FIG. 1 , that surrounds the filling at least in parts. At least the sensor cavity and the insertion channel  9  are accessible through the sheath  17 . The sheath  17  surrounds the filling along a circumferential direction C, which extends around the longitudinal direction L. In an embodiment, the sheath  17  extends continuously along the circumferential direction C. The sheath  17  may have an overall tube shape. 
     The arrangement  1  can be manufactured according to customer requirements, in particular with respect to the insertion channel  9 . In an embodiment, the insertion channel  9  is shaped complementary to the measuring object  11  for which the housing element  3  is intended to be used. At a customer&#39;s site, the arrangement  1  can be securely connected to the measuring object  11  by simply plugging the object  11  into the insertion channel  9 . The housing element  3  allows for a stable physical contact between the temperature sensor  3  and the measuring object  11 . 
     In the following, further details of the housing element  3  and of manufacturing the same are described with respect to  FIGS. 2 and 3 .  FIG. 2  shows a material for the housing element  3  prior to shaping and  FIG. 3  after shaping.  FIG. 2  shows a cross-sectional view in a cross section perpendicular to the longitudinal direction. 
     As shown in  FIGS. 2 and 3 , the housing element  3  is composed of a filling  19  and a sheath  17 . In an embodiment, the sheath  17  is in direct contact with the filling  19 , in particular after shaping the housing element  3 . Prior to shaping, two cavities  21  may be present in the filling  19  which will later be shaped to form the insertion channel  9  and a sensor cavity  23  for housing the temperature sensor  5 . 
     In the shaped state, the filling  19  forms a material bridge  25  between the insertion channel  9  and the sensor cavity  23 , as shown in  FIG. 3 . When the temperature sensor  5  and the measuring object  11  are arranged in the housing element  3  with a tight fit in their corresponding cavities, the material bridge  25  is intended to transfer heat from the measuring object  11  to the temperature sensor  5 . 
     The system comprising the filling  19  and the sheath  17  may also be regarded as a multitude of layers, the filling  19  forming an inner layer that may be in contact with the temperature sensor  5  and the measuring object  11  and the sheath  17  forming an outer layer that is on top of the inner layer. The invention does not exclude the presence of additional layers that are arranged between the filling  19  and the sheath  17 , on the outside of the sheath  17  and/or surrounding the sensor cavity  23  and/or the insertion channel  9 . In order to securely confine the filling  19  and to improve the stability of the housing element  3 , the sheath  17  in an embodiment extends continuously along a circumferential direction of the housing element  3 . 
     The filling  19 , in an embodiment, is made from a fluoropolymer material, for example Perfluoroalkoxy alkanes (PFA). This material may be helpful for removing a placeholder  27  after shaping the housing element  3  due to its non-sticking properties. Using a fluoropolymer material is beneficial because of its dielectric properties, in particular when the housing element  3  is used in high voltage applications. A placeholder  27  is indicated by the dashed line in  FIG. 3 . The filling  19  material may be chosen and/or designed with specific thermal conductivities depending on individual applications. 
     In an embodiment, the sheath  17  is made from a fluoropolymer material, for example Polytetrafluoroethylene (PTFE). The sheath  17  may be made from a heat shrinkable material. In an embodiment, the sheath  17  is made from a heat shrinkable fluoropolymer material. 
     For manufacturing the arrangement  1 , a temperature sensor  5  may be placed inside one of the cavities  21  and a placeholder  27  may be arranged in the other cavity  21 . The placeholder  27  is provided with the same diameter as the measurement object  11  for which the housing element  3  is intended to be used. The material of the filling  19  and the sheath  17  may then be heated using a heating arrangement  29 , which is only indicated by a hot wire  29  in  FIG. 2 . The heating arrangement  29  may comprise a heat gun or any other appropriate heater. The heating arrangement  29  and the placeholder  11  may together form a setup  33  according to the invention. 
     The heating arrangement  29  may heat the material of the housing element  3  such that the filling  19  increases its viscosity or, in other words, melts. At the same time, if the sheath  17  is made from a heat shrinkable material, the sheath  17  shrinks and applies pressure on the material of the filling  19  towards the temperature sensor  5  and the placeholder  27 . Thereby, the sensor cavity  23  is shaped complementary to the temperature sensor  5  and the insertion channel  9  is formed complementary to the placeholder  27 . The sheath  17  may facilitate the manufacturing process of the housing element  3  in that it may confine the filling  19 , in particular when the filling  19  is in a state of viscosity during manufacturing. 
     The placeholder  27  may, after shaping the insertion channel  9 , be removed from the housing element  3  by simply pulling it out of the insertion channel  9 . The placeholder  27  may then be used for shaping the insertion channel  9  of another housing element  3  at a later stage. If the actual measuring object  11  is used as the placeholder  27 , the measuring object  11  may remain in the housing element  3 . 
     The housing element  3  with the temperature sensor  5  in the sensor cavity  23  may be installed on the measuring object  11  by inserting a part of the measuring object  11  into the insertion channel  9 . Since the insertion channel  9  is formed complementary to the measuring object  11 , the measuring object  11  will fit tightly into the insertion channel  9  with a direct contact to the filling  19  and thereby to the material bridge  25 . The insertion channel  9  has an inner diameter that is basically identical to an outer diameter of the measuring object  11 . At the same time, due to the complementary shapes of the insertion channel  9  and the measuring object  11 , the housing element  3  is securely fixated on the measuring object  11 . 
     If this fixation should not be sufficient, additional elements  31  such as fixation elements may be embedded in the filling  19 , as shown in  FIG. 2 . An additional element  31  may be arranged in the filling  19  prior to shaping and then remain in the filling  19  after manufacturing. 
     Just by way of example, an additional element  31  may be a latching device that may protrude out of the housing element  3  for latching the same with a complementarily shaped element of the measuring object  11 . In other embodiments, an additional element  31  may be formed by a screw, a latch, a screw nut or other appropriate elements. 
     In other embodiments, the housing element  3  may be provided with more than one temperature sensor  5  and/or more than one measuring object  11  and the corresponding cavities  23  or insertion channels  9 .