Abstract:
Device for creating a temperature gradient, especially in gaseous media, comprising at least one ohmic resistor and at least two non-conducting insulators and at least one casing and at least one elastic element positioned between the non-conducting insulator and the casing.

Description:
[0001]    This invention concerns a device for creating a temperature gradient, especially in gaseous media. The device comprises at least one ohmic resistor, which can be designed meander-shaped, at least two non-conducting insulators, at least one casing and at least one elastic element. 
         [0002]    Devices for creating a temperature gradient are known. In devices according to prior art, wear often occurs in the device, which can affect the functioning or result in failure of the device. Such wear arises particularly from relative motions between the various parts of the device, which primarily occur when the device is used under non-static conditions. 
       SUMMARY OF THE INVENTION 
       [0003]    The object the invention is based on is therefore to create a device of the type mentioned at the outset, which can be reliably operated and is also easy to assemble. 
         [0004]    With prior art it has been found that degrees of spatial freedom of the ohmic resistor result in abrasion and wear in the device, and impairment of function or failure may occur. Such occurrences are to be avoided through the inventive structure of the device. With a meander-type design of the ohmic resistor, this is achieved, for example, by the fact that before being installed in the device, it has a shape stretched over angles α and β, thus upon installation in the device a pretension force is created, substantially limiting the room for motion by the various parts and minimizing wear. 
         [0005]    Another object of the invention is enabling simplified and reliable manufacture and/or assembly of the device invented. According to the invention, this task is solved in that special assembly aid elements are provided on the various parts of the device. 
         [0006]    The inventive assembly aid elements, which may be provided both on the at least one casing and on the at least two non-conducting insulators, may at the same time be designed such that the degrees of freedom of the various parts of the device are restricted, thus further minimizing and preventing wear. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    In the following, especially advantageous design forms are described as well as further developments of the inventive device using the attached drawings. 
           [0008]      FIG. 1  shows a heater for preheating air; 
           [0009]      FIGS. 2-5  shows a non-conducting insulator; 
           [0010]      FIG. 6  shows an ohmic resistor; 
           [0011]      FIG. 7  shows a portrayal of the forces on the ohmic resistor; 
           [0012]      FIGS. 8-12  shows two non-conducting insulators; 
           [0013]      FIG. 13  shows four non-conducting insulators; 
           [0014]      FIG. 14  shows the insulator casing; 
           [0015]      FIGS. 15-18  show a non-conducting insulator; 
           [0016]      FIGS. 19-20  shows casings; 
           [0017]      FIG. 21  shows a non-conducting insulator; and 
           [0018]      FIG. 22  shows a top view of the device according to  FIG. 21 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The heater shown in  FIG. 1 , especially for air preheating, especially in the intake tract of engines, has a casing  3 . The heating band  2  of the heater is arranged in a meander shape in two insulators  1  in a fashion to secure it against shifting such that the meander turning point of the heating band  2  contacts the retainer  14  for the insulator  1 . Such a heater is produced by one or more insulators, as shown for example, in  FIGS. 17 and 18 , being pushed from the side into the casing  5 , which is shown in  FIGS. 19 and 20 , such that the insulator/s  1  are prevented from falling out inadvertently by the assembly aid elements (sideways and upwards) in conjunction with the elastic elements  4 , which in  FIGS. 19 and 20  on the bottom side of the casing are identical to the assembly aid elements. In an alternative design, the insulators  1  from  FIGS. 3 ,  5 ,  17  &amp;  18  are put into a casing  5  from the top side of the casing  5  into the casing  5  or clicked into position with the help of the corresponding aid elements  10  &amp;  11 , as shown in  FIGS. 9 ,  10 , 11 ,  12 ,  13 ,  14 , 15  and  16 , doing so after one or more springs  4  have been put in or mounted at the place provided for them, e.g. aid element  10 . An ohmic resistor  2  bent in a meander shape is then inserted into two insulator elements created in such manner along with casing  5  for them, as can be seen in FIGS.  1 , 2 ,  4 ,  7  and  8 . This unit, consisting of ohmic resistor  2  and insulator  1  along with casing  5  is inserted into a casing  3 , and then connected to the electrical installation not shown. 
         [0020]      FIG. 2  shows a non-conducting insulator  1 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 . The retainer  14  is shaped approximately semi-circularly. The component forces F 2 , which result from the force F 1  of the elastic element act on the bearing surfaces in the radius  7 , as shown in  FIG. 3 , between heating band  2  and insulator  1 . The heating band  2  rests where the arrows F 2  are on the ceramic of the insulator  1  in the retainer  14 . 
         [0021]    A non-conducting insulator  1  is shown in  FIG. 3 . The insulator  1  has two retainers  14 , which assume the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . The retainer  14  is designed essentially semi-circularly. 
         [0022]      FIG. 4  shows a non-conducting insulator  1 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 . The retainer  14  has two slants, which form the angle γ. The angle γ should preferably be within a range of 30° and 90° . The component forces F 2 , which result from the force F 1  of the elastic element,  4  act on the slants. In the region of arrows F 2 , the heating band  2  visibly contacts the ceramic of the insulator  1  twice in the retainer  14  on the sides of the angle γ. 
         [0023]    In  FIG. 5  a non-conducting insulator  1  is shown, which, as can be seen in  FIG. 18 , has an assembly aid element  11  on its front side. On its rear side there is also an assembly aid element  11 . The assembly aid elements  11  correspond to the assembly aid elements  10  for the insulator casing, as is shown in  FIGS. 10 to 16 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . The retainer  14  has two slants, which form the angle γ. The angle γ should preferably be within a range of 30° and 90° . 
         [0024]    An ohmic resistor  2  is shown in  FIG. 6 , which coming from a flat steel element is shaped or bent in a meander form. The defined arrangement of angles α and β with the heating band  2  then compressed in the direction  8  drawn in results in pretension created in the heating band  2  as well as the jamming desired in the insulator  1 , which is indicated schematically by the horizontal force arrows and which can be seen advantageously in the assembled state in  FIG. 1 . 
         [0025]      FIG. 7  shows a portrayal of the forces on the ohmic resistor  2  put in under tension, which is used here as a so-called heating band. 
         [0026]      FIG. 8  shows two non-conducting insulators  1 . Two assembly aid elements  11  are positioned on the bottom sides of the insulators  1 , which is shown as a sectional drawing in  FIG. 8 . The spring  4  is positioned between the assembly aid element  10 , which may be designed either in male or female fashion, and the assembly aid element  11 . The assembly aid elements  11  correspond to the assembly aid elements  10  for the insulator casing  5 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 . 
         [0027]      FIG. 9  portrays two non-conducting insulators  1 , each of which has an assembly aid element  11  on their front side. On their rear sides there is also one assembly aid element  11  each. The spring  4  is positioned between the insulators  1  and the casing  5 . The assembly aid elements  11  correspond to the assembly aid elements  10  for the insulator casing  5 . 
         [0028]    The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . 
         [0029]    In  FIG. 10  two non-conducting insulators  1  are shown, which have one assembly aid element  11  each on their front sides. On their rear sides there is also one assembly aid element  11  each. The spring  4 , which in this design example is executed as a spring, is positioned between the insulators  1  and the casing  5 . The assembly aid elements  11  correspond to the assembly aid elements  10  for the insulator casing  5 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . 
         [0030]    In  FIG. 11  two non-conducting insulators  1  are shown, which have one assembly aid element  1  each on their front sides. On their rear sides there is also one assembly aid element  11  each. Two more assembly aid elements  11  are positioned on the bottom sides of the insulators  1 , and thus not visible here, which, however, is shown as a sectional drawing in  FIG. 8 . The spring  4  is positioned between the assembly aid element  10 , which may be designed either in male or female fashion, and the assembly aid element  11 . The assembly aid elements  11  correspond to the assembly aid elements  10  of the insulator casing  5 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . 
         [0031]    In  FIG. 12  two non-conducting insulators  1  are shown, which have one assembly aid element  11  each on their front sides. On their rear sides there is also one assembly aid element  11  each. Two more assembly aid elements  11  are positioned on the bottom sides of the insulators  1 , and thus not visible here, which, however, is shown as a sectional drawing in  FIG. 8 . The spring  4  is positioned between the assembly aid element  10  and the assembly aid element  11 . The assembly aid elements  11  correspond to the assembly aid elements  10  of the insulator casing  5 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . 
         [0032]      FIG. 13  shows four non-conducting insulators  1 , each of which has one assembly aid element  11  on their front sides. On their rear sides there is also one assembly aid element  11  each. Four more assembly aid elements  11  are positioned on the bottom sides of the insulators  1 , and thus not visible here, which, however, is shown as a sectional drawing in  FIG. 8 . The spring  4  is positioned between the assembly aid element  10 , which may be designed either in male or female fashion, and the assembly aid element  11 . The assembly aid elements  11  correspond to the assembly aid elements  10  of the insulator casing  5 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . On the short sides of the casing  5  there is one assembly aid element  10  each, which fix the insulators  1  in position elastically. 
         [0033]      FIG. 14  shows the insulator casing  5 , there being four pot-shaped protuberances  10  positioned on the bottom of the inside of the casing  5  to receive the springs  4  from  FIG. 8 . Four assembly aid elements  10  each are positioned on the front and rear sides of the casing  5 , each corresponding to the assembly aid elements  11  for the insulator  1  from  FIG. 13 . On the short sides of the casing  5  there is one assembly aid element  10  each, which fix the insulators  1  in position elastically. 
         [0034]      FIG. 15  shows two non-conducting insulators  1 , which have one assembly aid element  11  each on their front sides. On their rear sides there is also one assembly aid element  11  each. Two more assembly aid elements  11  are positioned on the bottom sides of the insulators  1 , and thus not visible here, which, however, is shown as a sectional drawing in  FIG. 8 . The spring  4  is positioned between the assembly aid element  10 , which may be designed either in male or female fashion, and the assembly aid element  11 . The assembly aid elements  11  correspond to the assembly aid elements  10  of the insulator casing  5 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . 
         [0035]    In  FIG. 16  two non-conducting insulators  1  are shown, which have one assembly aid element  11  each on their front sides. On their rear sides there is also one assembly aid element  11  each. Two more assembly aid elements  11  are positioned on the bottom sides of the insulators  1  and thus not visible here, which, however, is shown as a sectional drawing in  FIG. 8 . The spring  4  is positioned between assembly aid element  10  and assembly aid element  11 . The assembly aid elements  11  correspond to the assembly aid elements  10  of the insulator casing  5 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . 
         [0036]      FIG. 17  shows a non-conducting insulator  1 , which, has an assembly aid element  11  on its front side. On its rear side there is also an assembly aid element  11 . The assembly aid elements  11  correspond to the assembly aid elements  10  of the insulator casing, as is shown in  FIGS. 10 to 16 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . The insulator  1  has four recesses  13  for cooling the conductor  2  and two recesses  12  for cooling the springs  4 . 
         [0037]      FIG. 18  shows a non-conducting insulator  1 , which, has an assembly aid element  11  on its front side. On its rear side there is also an assembly aid element  11 . The assembly aid elements  11  correspond to the assembly aid elements  10  of the insulator casing, as is shown in  FIGS. 10 to 16 . The insulator  1  has two retainers  14 , which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . 
         [0038]      FIG. 19  shows a casing  5  made from a metal sheet, which has the assembly aid elements  10  (which have been punched from the same sheet) positioned to correspond to the complementary assembly aid elements of the insulator. In this embodiment a part of the respective side on the front and on the rear side of the casing  5  is bent inward approximately at a right angle so as to obtain an assembly aid element  10 , which prevents any possible movement of the insulator toward the top side of the casing  5 . Especially advantageous is the combined design of assembly aid element  10  and spring  4  in one element, realized in a single piece in the casing  5 . 
         [0039]      FIG. 20  shows a casing  5  made in one piece from sheet metal, which has the assembly aid elements  10  (which have been punched from the same sheet) positioned to correspond to the complementary assembly aid elements of the insulator. In this embodiment a part of the respective side on the front and on the rear side of the casing  5  is bent inward approximately at a right angle so as to obtain an assembly aid element  10 , which prevents any possible movement of the insulator toward the top side of the casing  5 . Especially advantageous is the combined design of assembly aid element  10  and spring  4  in one element, realized in a single piece in the casing  5 . 
         [0040]      FIG. 21  shows a non-conducting insulator  1 , which, has an assembly aid element  11  on its front side. On its rear side there is also an assembly aid element  11 . Another assembly aid element  11  is positioned on the bottom sides of the insulators  1 , which, for example, is shown as a sectional drawing in  FIG. 8 . The spring  4  is positioned between the dome  15 , which is provided to centre the spring  4 , and the assembly aid element  11 . The dome  15  is crimped so that the spring  4  can be fixed in position for better assembly. The assembly aid elements  11  correspond to the assembly aid elements  10  of the insulator casing  5 . The assembly aid elements  10  act as spring-action clips, which fix the insulator  1  in position such that it is pretensioned in spring-loaded fashion, after they had to execute a sideward movement outward during the assembly of the insulator  1  from the top, to then click into position in assembly aid elements  11 , as shown in  FIG. 21 . The insulator  1  has retainers  14 , which are not explicitly portrayed here and which receive the meander turning points  6  of the ohmic conductor  2 , as shown in  FIGS. 2 ,  4  and  8 . 
         [0041]      FIG. 22  shows a top view of the device according to  FIG. 21  without the non-conducting insulator  1 . The assembly aid elements  10  are visible on the insulator casing  5 , which has two crimped domes  15  on its bottom side, which both centre and fix the springs  4  in position during assembly. 
       LIST OF REFERENCE SYMBOLS 
       [0000]    
       
           1  Non-conducting insulator 
           2  Ohmic resistor 
           3  Casing 
           4  Elastic element 
           5  Insulator casing 
           6  Meander turning point 
           7  Radius 
           8  Direction indication for compressing during assembly 
           9  Pretension force 
           10  Assembly aid element, insulator casing 
           11  Assembly aid element, insulator 
           12  Recess 
           13  Recess 
           14  Retainer 
           15  Dome for centering spring