Abstract:
A fastening spring for fastening at least one component accommodated in a housing of an electric motor, in the prior art, has a bending zone which is exposed to strong mechanical stresses. 
     A fastening spring ( 1, 1 ′) of the invention has at least a second bending zone, so that the mechanical stresses are distributed over two bending zones.

Description:
This application is a 371 of PCT/DE 01/02290 filed Jun. 25, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention is based on a fastening spring for fastening at least one component, accommodated in a housing of an electric motor. 
     From U.S. Pat. 5,391,063, a fastening spring is known which is U-shaped and which fastens two magnets in a motor housing of an electric motor. However, the fastening spring has only one bending zone. A high degree of mechanical stress on the fastening spring in the bending zone leads to a considerable concentration of mechanical stress and rapid breakage of the spring. 
     In a fastening spring of the prior art, one is therefore forced to use spring steel as the material. Since spring steel is magnetically conductive, relevant magnetic flux losses occur. This leads to a loss of efficiency of the motor or to an increase in the installation space of the motor and makes the component more expensive. 
     SUMMARY OF THE INVENTION 
     The fastening spring of the invention has the advantage over the prior art that in a simple way, the mechanical stress on the fastening spring is reduced sharply and the spring force is increased. 
     The low resultant stress level on the fastening spring of the invention allows the use of either a less expensive material or a weakly magnetic special steel. The use of weakly magnetic special steel assures better efficiency of the motor. 
     The fastening spring of the invention makes it possible, at a relatively slight degree of stress on the material, to generate a restoring force. Moreover, because of the shape of the fastening spring, the tendency of a fastening spring of the prior art to snap off is overcome. 
     By the provisions recited in the dependent claims, advantageous refinements of and improvements to the fastening spring recited in claim  1  are possible. 
     It is advantageous that a first and/or second leg of a U shape rests at least in part on components, since as a result the spring force of the fastening spring engages the components optimally. 
     It is advantageous for a width of the fastening spring to be made less than a spacing between two opposed V-shaped segments, because this prevents fastening springs from catching on one another. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the invention are shown in simplified form in the drawing and described in further detail in the ensuing description. 
     Shown are 
     FIG. 1, a fastening spring of the invention in the undeformed state; 
     FIG. 2, a fastening spring of the invention in the installed state in a housing between two components; and 
     FIG. 3, a further fastening spring of the invention. 
    
    
     DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     FIG. 1 shows a fastening spring  1  of the invention in the undeformed state. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The fastening spring  1  has a U-shaped bottom. The U-shaped bottom is adjoined in both directions by a first leg  9  and a second leg  12 , respectively. The U-shaped bottom  5  and the legs  9 ,  12  form a U shape  14 . 
     One end  15  of the first leg  9  is adjoined by a first V shape  25 , which is formed of two legs  26 ,  28  that have a common point  27  where the legs intersect. The two legs  26 ,  28  of the V shape  25  open outward. One end  19  of the second leg  12  is adjoined for instance by a second V shape  29  with a point  31  where the legs intersect. The second V shape  29  also has two legs  32 ,  33  and is opened toward the outside. The first V shape  25  and the second V shape  29  are located opposite one another, for instance, while the leg intersection points  27 ,  31  have a spacing v from one another. 
     The fastening spring  1  is bent out of band material, for instance, with a rectangular cross section, which has a width b. To prevent loose fastening springs  1  in a supply container from catching on one another, it is appropriate for the spacing v to be greater than the width b of the fastening spring  1 . 
     FIG. 2 shows the fastening spring  1  in the installed state. The fastening spring  1  is installed in a housing  38  of an electric motor, where it fastens a first component  43  and a second component  44  to the housing  38  by restraint. In this exemplary embodiment, the components are magnets  43 ,  44  in the housing  38  of a stator. As components to be fastened in a housing  38  of an electric motor, magnetic short-circuit elements can for instance also be considered. 
     The housing  38  has a center line  39 . 
     The magnets  43 ,  44  are adapted for instance to an internal shape of the housing  38 , and inside the housing  38  they rest at least in part directly on an inner wall of the housing  38 . In this exemplary embodiment, one fastening spring  1  each is located between the magnets  43 ,  44 . The magnets  43 ,  44  have end faces  47 . The fastening spring  1  engages the end faces  47  of the magnets  43 ,  44 . Each magnet  43 ,  44  is pressed firmly against the housing  38  by the spring force of two fastening springs  1 . 
     Instead of the second fastening spring  1 , there can for instance also be a protrusion from the inner wall of the housing  38 , on which protrusion the end faces  47  of the two magnets  43 ,  44  rest. For fastening the magnets  43 ,  44  in the housing  38 , one fastening spring  1  then suffices, which is located between the two other end faces  47  of the magnets  43 ,  44 . 
     If only one component needs to be fastened in a housing  38 , then for the fastening spring  1  there must be a second protrusion from the inner wall of the housing  38 , on which protrusion the fastening spring can be braced. 
     The fastening spring  1  has a first region  51 , at the transition between the bottom  5  of the U and the legs  9 ,  12 ; a second region  52  on the ends  15 ,  19  of the legs; a third region  53  at the points  27 ,  31  where the legs intersect; and a fourth region  54  at the transition between the legs  28 ,  33  and end segments  35 ,  36 . The regions  52  and  54  of the fastening spring  1  are compressed upon installation, resulting in a mechanical stress on the regions  51 ,  52  and  53 . When the region  53  of the fastening spring  1  closes, that is, when the two V shapes  25  and  29  touch, the second stage of the spring characteristic curve comes into play, in which the first V shape  25  and the second V shape  29  become bent. 
     The spring force is distributed over a plurality of regions, resulting in a reduction in stress compared to a fastening spring of the prior art. 
     The symmetrical design and the two insertion chamfers in the region  51  serve to provide simple, unproblematic automatic mounting in the housing  38 . 
     FIG. 3 shows a further exemplary embodiment of the fastening spring  1 ′ of the invention. 
     The fastening spring  1 ′ is created by means of a refinement of the fastening spring  1  of FIG. 1, such that the two V shapes  25 ,  29  are each adjoined by a respective third v shape  60  and fourth V shape  61 .