Abstract:
The invention relates to a cable sleeve for guiding a cable in the inlet and outlet region of a hand-held tool. An end of the cable sleeve on the housing side is connected to the housing in a fixable manner, particularly in a form-fitting manner, so that advantageously no dust, dirt, or water may enter between the cable sleeve and the cable. According to the invention the cable sleeve has preferably a radial sealing element which corresponds to the cable and/or the housing in a sealing manner.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 35 USC 371 application of PCT/EP 2009/054965 filed on Apr. 24, 2009. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is based on a cable sleeve for guiding a cable in the inlet and outlet region of a hand-held tool. 
     2. Description of the Prior Art 
     Corded hand-held power tools can usually be connected to a power source by means of a cable. The cable is encompassed by an essentially coaxial cable sleeve at the cable outlet opening from the housing. 
     The cable sleeve assures a relatively low bending angle of the cable at the outlet opening of the housing under all operating conditions, thus preventing a sharp bending of the cable went corresponding forces are exerted on it. This protects the cable from being damaged by extreme bending and also from other mechanical influences in the region in which it is enclosed by the cable sleeve. 
     During operation of the hand-held power tool, the cooling air of the electric motor is usually drawn into the housing from the outside through inlet openings, travels past the motor, and is blown out again through outlet openings. As a result, negative pressure is produced in the housing, which causes air from the outside to flow into the housing through all existing openings and gaps in corresponding regions, including through the gap between the cable and cable sleeve. This gap is present due to the relatively high production tolerances of the cable and cable sleeve and due to the fact that only a few types of cable sleeve are used for a wide variety of cables of different external diameters that are required due to the various voltage systems worldwide. For this reason, it is currently necessary to stock a plurality of cable sleeve types with various inner diameters. 
     Air drawn in by means of the cable sleeve conveys dust particles from the work environment into the interior of the power tool. For example when using an angle grinder, these dust particles are frequently metallic and on the inside of the housing, can settle on switches or other electrical, voltage-carrying elements. As a result, the conductive metallic particles can form bridges between the different voltage potentials. Corresponding arcing can result in breakdowns of the hand-held power tool and can be hazardous to the user. 
     ADVANTAGES AND SUMMARY OF THE INVENTION 
     Depending on the embodiment of the external and/or internal shape of the cable sleeve, the invention can perform a sealing action and can provide tolerance compensation. It is therefore not necessary to use a specific cable sleeve type for each country-specific design of the hand-held power tool, thus reducing the number of parts required. In addition, due to its new embodiment, the cable sleeve can simultaneously function as a power cord strain-relief element. 
     Because the cable sleeve encompasses the cable in a radially sealed, frictional, nonpositive fashion, water, dust, and the like cannot penetrate into the interior of the housing, particularly because the end of the cable sleeve oriented toward the housing has a ring-like sealing element that rests in a sealed fashion against the outer circumference of the cable. 
     Because the cable sleeve is provided with a helical sealing lip that protrudes radially inward, the cable can be inserted axially into a narrow cable sleeve by turning it like a screw. 
     The sealing action is improved by virtue of the fact that the cable sleeve has a plurality of ring-like sealing elements at its end oriented toward the housing. 
     The sealing action can be improved and the manufacture of the cable sleeve can be simplified by virtue of the fact that the ring-like sealing elements are embodied in the form of annular beads, particularly in the form of injection-molded O-rings composed of a material that differs from the material of the sleeve, in particular has softer elastic properties than it. 
     The sealing action for particular circumstances and special applications can be improved by virtue of the fact that the ring-like sealing elements are embodied in the form of hollow cylindrical plugs, in particular wedge-shaped plugs, that protrude into the hollow cylinder of the cable sleeve, particularly at its front end. 
     Another easy-to-install sealing variant is achieved by virtue of the fact that a smooth, cylindrical, hollow connecting piece of the cable sleeve protrudes axially into the interior of the housing and in the installed position therein, is encompassed in a contracting fashion so that a region of the hollow connecting piece rests in an annular, sealed fashion against the outside of the cable. 
     It is also possible to use conventional cable sleeves in a sealed fashion by virtue of the fact that clamping jaw-like parts, in particular parts belonging to the housing, are able to act on the hollow connecting piece. 
     The sealing action can be improved with extremely simple means by virtue of the fact that the housing is composed of housing shells, each of which has a clamping jaw-like part that belongs to a respective housing shell. 
     The sealing action can be improved with even simpler means by virtue of the fact that an annular shell part, in particular belonging to the housing, is able to act on the hollow connecting piece in the radial direction. 
     The sealing action can be improved with even simpler, conventional, inexpensive means by virtue of the fact that the annular shell-like part is embodied in the form of a tension sling, in particular a twistable wire and/or pipe clamp and/or cable strap. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained below in conjunction with an exemplary embodiment and associated drawings. 
         FIG. 1  shows a longitudinal sections through a hand-held power tool housing equipped with the cable and cable sleeve according to the invention, 
         FIG. 2  shows another longitudinal section through the hand-held power tool housing equipped with the cable and cable sleeve according to the invention, 
         FIG. 3  shows the cable sleeve according to  FIGS. 1 and 2 , in a longitudinal section through a detail, 
         FIG. 4  shows another cable sleeve with a helical radial inner sealing lip, 
         FIGS. 5 and 6  each show a variant of the cable sleeve with a plurality of radial inner sealing lips, 
         FIG. 7  shows a cable sleeve with a hollow, cylindrical plug as a sealing means, 
         FIG. 8  shows a cable sleeve with a crushing region, which, acting as a sealing means, is acted on by clamping jaws, 
         FIG. 9  shows a cable sleeve with a crushing region, which, acting as a sealing means, is acted on by an annular bracket-like sleeve. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     At its front end  30  situated inside the housing, a cable sleeve  22  depicted in  FIGS. 1 ,  2 , and  3  has an annular, circumferential, inward-oriented radial sealing lip  28  that encompasses a cable, which is pulled into it, in an elastically pressing and therefore axially sealed fashion; the hollow cylinder  26  has a conical wall that becomes thinner toward its end  32 , which encompasses the cable  36  and shields it from the outside. The significantly thicker wall region in the vicinity of the front end  30  absorbs a greater bending moment than closer to the end  32  and therefore in the event of powerful bending forces acting on the cable  36 , prevents a sharp bending of the cable  36  relative to the longitudinal axis  24  of the housing  10 , i.e. by an acute angle of approximately 90° with a minimal bending radius, and thus also prevents breakage of the cable strands inside the cable  36 . 
     On the outside, the cable sleeve  22  is conventionally embodied and can be fixed in position by means of an external annular groove  34 , which is associated with a matching annular projection  16  of the housing  10 , and by means of its front end  30 , which is associated with a rib-like axial stop  18  of the housing  10 . The housing wall  11  of housing  10  constitutes a cable sleeve outlet opening  14 , which encompasses the cable sleeve  22  through which the cable sleeve  22  protrudes outward, and as it does so, conveys the cable  36  to the inside. 
     The sealing, insertion, and withdrawal properties of the cable in relation to the cable sleeve  22  can be selected through the embodiment of the sleeve&#39;s angle in the region of the sealing lip. If the sealing lip  28 , as depicted in  FIG. 3 , has a saw-tooth structure, it is safe to assume that the cable sleeve  22  has a relatively low, assembly-friendly cable pull-in force as compared to a higher pull-out force. This facilitates strain relief. To this end, it is also possible to provide corresponding grooves or cams on the cable  36 . 
       FIG. 4  shows a cable sleeve  220  having a front end  300  and an end  320 . The cable sleeve  220  is provided with a helical inward-oriented radial sealing lip  280  that can have a stepped inner diameter for a use with cables of different diameters. In this connection, when the cable sleeve  220  is used for large cable diameters, sealing lips that are too tight can be removed mechanically or thermally or in some other way. According to this principle, the cable  36  is screwed into the cable sleeve  220  like a screw into the thread of a nut. In this case, it is possible for a cable sleeve  220  that is manufactured in one piece to have material combinations between the conventional sleeve region and the sealing region. 
     In a variant of the cable sleeve  220  with a helical, stepped sealing lip, closer to a more elastic or more stretchable region of the hollow cylinder  260 , it is not necessary to remove excessively large sealing lips because they are able to move radially out of the way along with the hollow cylinder  260  and its wall. 
     The cable sleeves  2200 ,  22000  shown in  FIGS. 5 and 6  each have two parallel, radial, inner sealing lips  2800 ,  28000  constituted by integrated annular beads or O-rings composed of a material that is the same as or different from the material of the respective cable sleeve. Like the helical sealing lip according to  FIG. 4 , these can each have a different respective inner diameter for different thicknesses of cable; for thicker cables, excessively tight sealing lips can be removed mechanically or thermally or in some other way. A cable that has been pulled in is elastically enclosed in a sealed fashion in accordance with the active principle of an O-ring. Other shapes of the annular bead—e.g. rectangular, square, or elliptical—and/or other materials of a one-piece cable sleeve for the conventional sleeve region and the sealing region are also conceivable. 
     The advantage of this variant is the ability to select a suitable size of the O-rings; it is also possible to select from a broad range of materials for the sealing means. In these cable sleeves, it is also advantageous for the sealing cross-sections to be embodied as rectangular, square, elliptical, saw-toothed, etc. 
     The front end  301  of the cable sleeve  221  shown in  FIG. 7  has an elastic, hollow, cylindrical wedge element  281  that is pressed into the inside of the hollow cylinder  263  of the cable sleeve  221  and correspondingly fixed in place, e.g. by means of frictional, nonpositive engagement, a mechanical undercut, a rib on the housing, or glue. The pressing action slides the wedge element in a sealed fashion into the pre-existing gap between the cable sleeve and the cable, not shown. Another variant of a cable sleeve manufactured of one piece in accordance with the design shown in  FIG. 7 , equipped with an integrated cone, is not shown in the drawing. 
     The front end  302  of the cable sleeve  222  shown in  FIG. 8  has a protruding region  29  similar to a pipe-connecting piece, with a narrow wall thickness. This region  29  performs its sealing function in relation to an inserted cable once a radial force is exerted on it from the outside. For this purpose, opposing ribs  13  are integrated into the two shells  12  (one shell  12  is shown in  FIG. 1 ) of the housing  10  and when the shells  12  are assembled, act on the region  13  from the outside like a pair of pliers, deforming it in a cross-sectionally constricting fashion, producing a seal in relation to the inserted cable. Alternatively, it is also possible for a plurality of ribs to be arranged one after another and laterally offset from one another, from the one shell to the other shell. By means of this measure, the additional deformation of the power cord could function like a strain-relief element. 
     The front end  303  of the cable sleeve  223  shown in  FIG. 9  has a protruding region  291  similar to a pipe connecting piece, with a narrow wall thickness like the cable sleeve according to  FIG. 8 . This region  291  performs its sealing function in relation to an inserted cable once a radial force is exerted on it from the outside. For this purpose, a crushing element  11  is provided, which acts on the region  13  from the outside, deforming it in a cross-sectionally constricting fashion, producing a seal in relation to an inserted cable. The crushing element can, for example, be a twistable wire, pipe clamp, cable strap, or similar device. According to this principle, the seal is achieved by compressing and constricting the sleeve from the outside in the direction toward the power cord. Another advantage is the possibility of prefabricating the combined unit composed of the sleeve and cable. 
     Furthermore, gluing the cable sleeve to the cable would produce a sealed, strain-relieving cable inlet. Filling the intermediate space between the cable sleeve and cable with a corresponding foam material is also a conceivable way to achieve a durable, sealed connection. As another variant, a cable sleeve that is vulcanized onto the cable is provided and/or the cable sleeve is injection molded around the cable and/or the cable sleeve is embodied in the form of an elastic shrink sleeve. 
     The above-mentioned cable sleeve principles can be partially combined with one another. This yields additional variants. Corresponding sealing means can be situated in the hollow cylinder  26  over the entire length of the cable sleeve and embodied in accordance with the production process and assembly process. 
     In other variants, the cable sleeves can also be embodied of multiple parts or in the form of shells in order to facilitate assembly. 
     The foregoing relates to the preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.