Abstract:
The invention relates to a bumper that features holders suitable for the acceptance of ultrasound transducers. The objective of the invention is to improve the coating properties of such a holder by avoiding mold seams. The invention essentially consists in providing the holder with an integrally cast panel which covers mold seams on the transducer and/or divides the holder into two holder segments, with the first holder segment being integrally cast onto the bumper.

Description:
TECHNICAL FIELD 
     The invention relates to a preferably overpaintable bumper with a holder for acceptance of a an ultrasound transducer. 
     BACKGROUND OF THE INVENTION 
     Ultrasound transducers are increasingly being inserted into the bumper of a motor vehicle for use with distance warning equipment, parking aids, and similar equipment. To this end, a series-manufactured bumper must be prepared for acceptance of the ultrasound transducer. This is achieved by drilling an opening and inserting a holder which, in turn, accepts the ultrasound transducer. The holder is frequently welded permanently to the bumper. Exchangeable holding devices have also been proposed, as described in the applicant&#39;s patent application 195 28 474.7, through which transducers of various dimensions can be fitted to the uniform acceptance opening of a bumper. 
     There is a growing trend toward painting the bumpers on motor vehicles. The disadvantage of known bumpers that are equipped with a holder for acceptance of an ultrasound transducer is that they feature relatively narrow mold seams, which result in a poor appearance after overcoating. In addition, paint tends to creep along the adjacent interfaces of the mold seams and then harden. 
     Consequently, the objective of the invention is to specify novel designs of bumper holders that are particularly advantageous in terms of painting of the bumper. 
     Thus, an initial solution of the objective consists, in principle, in immediately connecting a first holder to the bumper in one piece and then later connecting a second holder segment permanently to the first holder segment. The advantage here consists in the fact that it is possible, to mold the first holder segment directly to the bumper during its manufacture, with the first holder segment being installed in a relatively simple manner. Consequently, the casting molds are not required to meet any special specifications, as the connecting elements between the holder and the transducer casing, which are known, for example, from 195 28 474.7, are not integrally cast directly to the bumper. In this respect, no special advance performance is provided for the event that the bumper is to be delivered without ultrasound transducers, and the addition of the first holder segment only adds a slight complication to the shape of the bumper. The opening in the bumper needed for acceptance of the transducer casing can either be incorporated immediately during the bumper casting process or this opening can be cut out later for installation of the transducer. The primary advantage of this invention solution consists in the fact that a visible mold seam, which would otherwise be created when the entire holder is subsequently welded into the bumper, is avoided on the visible surface of the bumper between the bumper and the holder. 
     An additional advantage consists in the fact that the second holder segment, which is later joined to the first segment, can assume a certain adapter function in that it can be used, for example, to match the external dimensions of various transducers to the internal dimensions of the first holder segment. All that is required to achieve this is to pull an annular protrusion of the second holder segment forward to the visible end of the transducer casing on the bumper, with the inner diameter of the second casing segment matching the outer diameter of the corresponding transducer casing. 
     Measures are disclosed for purposes of permanently connecting the two holder segments to one another. 
     To enlarge the connection surface between the two holder segments, it is advantageous to apply projection or recess features on the bumper. The two corresponding connection elements (projection and recess) provide both for centering and for enlargement of the connection surface. However, as described above, the use of corresponding steps in the two holder segments can also result in an advantageous solution which, at the same time, can exercise a certain adapter function. 
     An especially simple design of a bumper equipped with a holder results when the projection adjoins a simple clearance hole through the bumper. The transducer casing is secured by a catch inside the complicatedly designed second holder segment, which is later joined to the first holder segment. 
     A second solution of the problem is provided in a bumper according to the invention by equipping the clearance hole for the holder with an inwardly projecting console that serves as a panel to cover the perimeter of the transducer. As both the cross-sectional area of the transducer casing and the seal connecting the inner surface of the casing with the outer surface of the resonator lie within the radially outer perimeter of the transducer, the console-like projection can be used to cover both the cross-sectional area of the casing and an annular partial surface of the seal, so that two mold seams are covered by the projection. At the same time, it is also possible to simplify the shape of the casing, as it would otherwise also have to include an internally oriented projection to secure the seal against the casing. For purposes of improving the radiating effect of the resonator and improving its appearance, the face of the resonator concludes with the front face of the bumper. The resonator is pulled forward in relation to the seal to align the front edge of the resonator with the leading edge of the projection, so that they are at the same level. In this case, it is important to ensure that a sufficient space exists between the casing surface of the resonator and the inner surface of the projection, so as to prevent the two parts from being glued together by a penetrating thin layer of paint, which would make it difficult to exchange the transducer. 
     According to this claim, the portion of the bumper and projection that encloses the membrane is funnel-shaped, which results in an advantageous radiation density. An advantageous further development of the invention may be achieved by connecting a portion of the holder to the bumper in one piece. Thus, not only are the mold seams associated with the installation of a holder into the bumper avoided, but the mold seams on the transducer itself are also partially covered and the design of the transducer is simplified at the same time. The comments made earlier regarding the specifications for the bumper casting mold also apply here, so that the design of the casting mold can be kept relatively simple in spite of the lack of multiple mold seams. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts the structure of a bumper known in the art. 
     FIG. 2 depicts a highly simplified image of a bumper in which the holder is assembled from a first holder segment and a second holder segment. 
     FIG. 3 depicts a smaller-scale image of the second holder segment shown in FIG. 2. 
     FIG. 4 depicts a holder with a projection covering the mold seams. 
     FIG. 5 depicts a larger-scale depiction of the transducer depicted schematically in FIG. 4. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the schematic drawing in FIG. 1, a holder 2 is inserted into the partially depicted bumper 1 and is welded or glued to the bumper 1. A first mold seam 3 results between the bumper 1 and the holder 2. The holder 2 features a clearance hole 4 into which the casing of an ultrasound transducer is inserted. The transducer casing is locked into the holder 2 by suitable means. Examples of locking methods are described in DE195 28 474.7 and will not be described again here. The significant element of the known design of the holder is that a second mold seam 6 is provided between the transducer casing 5 and the inner wall of the clearance opening 4 in addition to the first mold seam 3, as well as a third mold seam 9 between the radial wall 7 and the casing surface of the resonator 8. According to the invention, this type of design can be simplified in that, according to FIG. 4, a radial projection (console) 10 is featured on the holder 2 that acts as a panel and covers the leading edge of the transducer casing 5, as well as a portion of the seal 11, elastically suspending the resonator 8 from the inner wall of the transducer casing 5. As a result, a mold scam 6 is avoided and the casing 5 is more simply structured in that the projection 10 acts as a limit stop for the casing 5 and the seal 11, so that the radial wall 7 (FIG. 1) of the casing 5 can be eliminated. It should also be noted that the third mold seam 9 is not as narrow as it is in the known design depicted in FIG. 1, as it would otherwise easily become covered with pain and prevent removal of the transducer from the holder. 
     In summary, in the design according to the invention depicted in FIG. 4 the mold seam 6 is eliminated, clogging of the mold seam 9 during overpainting is avoided and, finally, the design of the transducer casing is simplified. 
     FIG. 5, which provides an enlarged and spatial depiction of a possible execution of the holder according to FIG. 4, also depicts locking clips 12 that enable the transducer casing 5 to be locked into the casing surface 13 of the holder 2. As is evident in FIG. 5, the locking clips 12 are reinforced with injected shock absorbing legs 14 to securely prevent the transducer 5 from slipping out of the holder 2. As is evident in FIG. 5, the projection 10 encompasses a clearance surface 15 into which a partial surface 16 of the resonator projects. Although this can be circular, to generate a suitable beam in this particular case it is designed in such a way that the partial surface 16 consists of a circular surface from which two lateral circle segments have been removed. 
     FIG. 2 depicts a second means of avoiding another mold seam (additional). A holder consisting of two holder sections is connected to the bumper 1. In terms of the invention, it is important that the first holder segment 17 is integrally cast with the bumper 1 in one piece, thus eliminating the mold seam visible in FIGS. 1 and 2. The reason for constructing the holder 2 out of a first holder segment 17 and a second holder segment 18 consists in the fact the featured locking clips and possible bayonet joints make the design of the lower second holder segment 18 relatively complex, as is evident in FIG. 5, and that the objective is to avoid such complicated shaping in the bumper casting mold. This type of advance performance in the casting mold may not be economical, as not all vehicles feature transducers in their bumpers. Furthermore, the second holder segment 18 can assume a certain adapter function with respect to varying transducer casing 5 dimensions, in that the second holder segment is adapted to the outer surface of the transducer casing 5 and simultaneously possesses a matching interface with the first holder segment 17, so that these two parts, which may feature different transducers, can be joined together. The complex design of the second holder segment 18 of the holder component 2 is suggested in FIG. 3. 
     Another important feature of the invention is the use of a centering projection 19 on the first holder segment 17 that matches the centering recess 20 (see FIG. 3) of the second holder segment 18. Joining together the projection 19 and the recess 20 produces a larger connection surface while simultaneously centering the two holder segments against one another. The use of matching projections and recesses that are also interchangeable with respect to the first and second holder segment provides a certain key function, in that only matching holder parts can be joined together, thus preventing the installation of incorrect transducers. 
     The execution depicted in FIG. 2 can also be combined with the execution depicted in FIG. 4, thus eliminating two mold seams and combining the advantages offered by both designs. Consequently, the resulting bumper with an assembled holder and an inserted transducer is particularly well-suited for painting. A possible separating line is indicated by the letter T in FIG. 5.