Abstract:
A protective device includes a mechanical protective sheath ( 20 ) and a thermal protective nozzle ( 30 ) mounted at one end ( 21 ) of the mechanical protective sheath ( 20 ), the mechanical protective sheath ( 20 ) including a tubular textile structure that is deformable by compression in the longitudinal direction of the mechanical protective sheath ( 20 ), the textile structure having, in a longitudinal compression area, an expanded sheath portion ( 25 ) adapted to interact by the reversion of one end ( 32 ) of the thermal protective nozzle ( 30 ). The device can be used in particular for protecting an element ( 11 ) connecting to a sensor ( 12 ) of an engine ( 13 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention concerns a thermal and mechanical protection device. 
     It concerns in particular the protection of a connection cable used in automobile vehicles for the connection of a sensor mounted on an automobile vehicle engine to a cable harness. 
     2. Description of the Related Art 
     In this type of application, it is necessary to protect the connection cable not only against mechanical aggression but also against the intense heat generated in the environment of the engine. 
     In particular, the presence of the exhaust gas evacuation tube (EGR tube) leads to very intense radiation of heat which can lead to a connection cable melting or cause short circuits. 
     Thus there is known from the document US 2007/0191755 a protection device for a connection cable including a mechanical protection sheath and a thermal protection end-piece mounted at one end of the mechanical protection sheath. 
     In the above document, the mechanical protection sheath is a convoluted plastic sheath. The thermal protection end-piece is produced from a layer of insulating material and a reflecting layer. 
     A positioning and fixing device makes it possible to fit the thermal protection end-piece detachably to one end of the mechanical protection sheath. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to propose a thermal and mechanical protection device that is simple to use and in particular facilitates fitting the element protected by the protection device. 
     To this end, a first aspect of the present invention concerns a protection device including a mechanical protection sheath and a thermal protection end-piece mounted at one end of said mechanical protection sheath. 
     According to the invention the mechanical protection sheath comprises a tubular textile structure that is deformable by compression in the lengthwise direction of the mechanical protection sheath and said textile structure has in a lengthwise compression area an expanded sheath portion adapted to cooperate with one end of said thermal protection end-piece by being turned back on itself. 
     Thanks to the textile structure of the mechanical protection sheath that is deformable by compression, it is possible to shorten the length of the protection device in order to leave exposed one end of an element to be connected that is protected by the protection device. There is further obtained the turning back of the expanded sheath portion on itself in the vicinity of the thermal protection end-piece. The turning back of the mechanical protection sheath on itself in the expanded sheath portion makes it possible to create a pleat inside the mechanical protection sheath. This pleat in the sheath is held in shape by the thermal protection end-piece. The position in which the thermal protection end-piece and the turned back expanded sheath portion cooperate makes it possible to move aside the protection device and fit the element to be connected without impediment. 
     Moreover, this cooperation position being obtained by simple lengthwise compression of the mechanical protection sheath, it is possible to carry out this operation on the protection device several times, in particular in the event of further intervention following the first fix. 
     In one practical embodiment of the invention, the mechanical protection sheath is deformable between a position of unstable equilibrium in which said expanded sheath portion is turned back on itself and retained by one end of the thermal protection end-piece and a rest position in which said mechanical protection sheath is aligned with said thermal protection end-piece and the mechanical protection sheath is movable from said position of unstable equilibrium to said rest position by elastic return of said mechanical protection sheath to said rest position. 
     Thanks to the elastic return force acting between the unstable equilibrium position and the rest position of the mechanical protection sheath, it is possible, after fitting, to obtain automatic positioning of the protection device, and in particular secure positioning of the thermal protection end-piece at the end of the mechanical protection sheath, independent of the operator. 
     In one advantageous embodiment of the invention, the expanded sheath portion is held by turning it back on itself over an exterior surface of said thermal protection end-piece. 
     Thus the mechanical protection sheath may be retained in a lengthwise compression area by simply turning it back on itself over the thermal protection end-piece, thereby creating a position of unstable equilibrium sufficiently reliable to be maintained while the operator manipulates the element to be connected that is protected by the protection device. 
     The mechanical protection sheath preferably consists of a tubular braid of monofilaments. 
     Thanks to this braided structure of the mechanical protection sheath, evacuation of heat from around the protection device is facilitated and in particular it is possible to prevent confinement of heat in the thermal protection end-piece. 
     Moreover, this braided structure makes it possible to obtain a tubular textile structure that can be expanded in the widthwise direction by compressing it in the lengthwise direction. 
     A second aspect of the present invention is the use of a protection device of the invention to cover a connection element and in particular a connection element of a sensor mounted on an automobile vehicle engine. 
     Finally, a third aspect of the present invention aims to protect the use of the protection device of the invention to cover a connection element during fitting of said connection element to another connection element, such use comprising the following steps:
         compressing the mechanical protection sheath lengthwise to obtain an expanded sheath portion around said connection element;   turning said expanded sheath portion back on itself by pressing against an end of the thermal protection end-piece;   fitting said connection element to the other connection element; and   releasing said expanded sheath portion turned back on itself for elastic return of said mechanical protection sheath to a rest position.       

     This use of the protection device has features and advantages analogous to those described above with reference to the protection device used. 
     Other features and advantages of the invention will become more apparent in the course of the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       In the appended drawings, provided by way of non-limiting example: 
         FIG. 1  is a view in lengthwise section of a protection device of a first embodiment of the invention mounted on a connection element; 
         FIG. 2  is a view analogous to  FIG. 1  showing compression of the protection device in the lengthwise direction; 
         FIG. 3  is a view analogous to  FIG. 1  showing the protection device in an unstable equilibrium position; 
         FIG. 4  is a perspective view of a protection device of a second embodiment of the invention mounted on a connection element; 
         FIG. 5  is a view analogous to  FIG. 4  showing the protection device in an unstable equilibrium position; and 
         FIG. 6  is a view in lengthwise section showing the protection device in the  FIG. 5  unstable equilibrium position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A protection device of a first embodiment of the invention is described next with reference to  FIGS. 1 to 3 . 
     The protection device is illustrated here in an application to motor vehicles. 
     By way of nonlimiting example, the protection device  10  is mounted on a connection element  11  of a sensor  12  mounted on an engine  13 . 
     The sensor  12  may be a top dead center (TDC) sensor, for example, for detecting the position of an engine cylinder. The sensor  12  may equally be an oxygen sensor for monitoring the operation of the engine  13 . 
     More particularly, the protection device  10  extends in a lengthwise direction X to protect a connection cable  14  connected to a connector  15  adapted to be fitted to the sensor  12 . 
     The elements to be protected are well known in the art and need not be described in more detail here. 
     The protection device  10  includes a mechanical protection sheath  20  and a thermal protection end-piece  30  mounted at one end  21  of the mechanical protection sheath  20 . 
     Thus in a rest position the mechanical protection sheath  20  extends from a first end  21  to a second end  22  over the total length of the protection device shown in  FIG. 1 . 
     As clearly shown in  FIG. 1 , the first end  21  of this mechanical protection sheath  20  thus covers not only the connection element  11  but also part of the connection of the sensor  12 . 
     At its second end  22 , the mechanical protection sheath  20  may be fastened to the connection cable  14  by means of a standard clamping collar. 
     This fitting at the second end  22  of the mechanical protection sheath  20  thus makes it possible to fasten together the connection element  11  and the protection device  10  before fitting them to the engine. 
     In this embodiment, the mechanical protection sheath  20  consists of a tubular textile structure produced from braided monofilaments. Here it is a closed tubular sheath obtained directly by tubular braiding. 
     The monofilaments used to produce the braided sheath are of plastic with a high modulus of elasticity. 
     For example, these monofilaments may consist of polyester or polyamide. Of course, other materials having enhanced technical characteristics may be used, in particular if the protection device  10  must be used in environments with intense heat radiation. 
     The length and the diameter of the tubular textile structure are linked to the application and in particular to the dimensions of the connection element  11  to be protected. 
     This braided tubular textile structure has the feature of being deformable by compression in the lengthwise direction X of the mechanical protection sheath  20  and of forming, as clearly illustrated in  FIG. 2 , in the area  24  of lengthwise compression, an expanded sheath portion  25 . 
     The dimensions of this expanded sheath portion  25 , and in particular its diameter, depend in particular on the braiding angle of the monofilaments of the textile structure and on the number of wicks used to produce the braided structure. 
     By way of nonlimiting example, the expanded sheath portion  25  may have a diameter D substantially equal to twice the diameter d of the mechanical protection sheath  20  in the rest position. 
     Although in this embodiment the mechanical protection sheath has a tubular structure, a different shape may be used, in particular a structure flared at one end. 
     The thermal protection end-piece  30  may be produced from a heat screen formed to cover a portion of the mechanical protection sheath  20  in the vicinity of the first end  21 . 
     By way of nonlimiting example, the thermal protection end-piece may be produced by winding a heat screen into a substantially cylindrical shape and fastening the lengthwise edges together, for example welding or gluing them together. 
     This heat screen may be produced from a textile coated with a layer of aluminum. For example, a sheet of aluminized polyester may be used. 
     Of course, the structure of the heat screen is not limiting on the invention. More generally, it may consist of plastic fibers or inorganic fibers, and in particular glass fibers, woven or not, coated with a layer of aluminum. 
     Likewise, the cylindrical shape shown in  FIGS. 1 to 3  is not limiting on the invention, and the thermal protection end-piece may also have a cone shape flared in the direction of the sensor  12  in order to adapt to various protection applications. 
     Thus the thermal protection end-piece  30  extends in the lengthwise direction X over a portion of the protection device  10  in order to protect in particular the connection (the connection part of the sensor  12  and the connector  15 ) from thermal aggression from the surrounding environment. 
     In the application described here, the engine sensors are often subjected to high levels of radiation from the exhaust manifolds or pipes. Thus the thermal protection end-piece  30  must make it possible to protect the connection from an ambient temperature that can reach 150° C., in order to avoid damage to the connector or a short circuit. 
     By way of nonlimiting example, the length of the thermal protection end-piece  30  in the lengthwise direction X may be between 2 and 10 cm inclusive and for example between 3 and 6 cm inclusive. 
     The total length of the protection device may be between 15 and 20 cm inclusive. 
     The thermal protection end-piece  30  is preferably mounted at the end  21  of the mechanical protection sheath  20  at a first end  31  of the thermal protection end-piece. 
     The fixing means used may consist, for example, of one or more clips  18  for fastening the ends  21 ,  31  of the mechanical protection sheath  20  and the thermal protection end-piece  30 . 
     Of course, any other fixing technique may be used here and in particular gluing or welding. 
     On the other hand, the mechanical protection sheath  20  extends freely inside the thermal protection end-piece  30  and extends out of the thermal protection end-piece  30  beyond its second end  32 . 
     In this embodiment, as shown in  FIG. 1 , the diameter d of the mechanical protection sheath  20  substantially corresponds to the inside diameter of the thermal protection sheath  30 . Of course, the diameter d of the mechanical protection sheath  20  could be smaller, the end  21  of the mechanical protection sheath  20  then being slightly deformed into a cone shape to enable the fixing of the ends  21 ,  31  of the mechanical protection sheath  20  and the thermal protection end-piece  30 . 
     It will be noted that the breathable structure of the braided mechanical protection sheath facilitates the circulation of air and in particular the evacuation of heat from around the thermal protection end-piece  30  toward the opposite end  22  of the mechanical protection sheath  20 . 
     As clearly shown in  FIGS. 2 and 3 , on lengthwise compression of the mechanical protection sheath  20 , the expanded sheath portion  25  makes it possible to initiate turning the mechanical protection sheath  20  back on itself in this area, in cooperation with the end  32  of the thermal protection end piece  30 . 
     Here the diameter D of the expanded sheath portion  25  is greater than the external dimensions of the thermal protection end-piece  30 , here its diameter. 
     Accordingly, in this embodiment, the expanded sheath portion  25  is retained by turning it back over an exterior surface  33  of the thermal protection end piece  30 , as shown in  FIG. 3 . 
     More specifically, the expanded sheath portion  25  forms a re-entrant annular ring-shaped pleat  26  inside the mechanical protection sheath  20 . In this embodiment the pleat  26  extends over a corresponding part of the surface  33  in the vicinity of the end  32  of the thermal protection end-piece  30 . 
     The pleat  26  is thus formed of a re-entrant sheath portion inside the expanded sheath portion  25  between an external end  26   a  of the expanded sheath portion  25  and an internal end  26   b  connected to the portion of the mechanical protection sheath  20  inside the thermal protection end-piece  30 . 
     When the mechanical protection sheath  20  goes to the position shown in  FIG. 3 , the second end  32  of the thermal protection end-piece  30  constitutes a bearing area for turning the expanded sheath portion  25  back on itself over the second end  32  of the thermal protection sheath  30 . 
     Thanks to the elastic structure of the braid, the pleat  26  in the expanded sheath portion  25  turned back on itself retains the end  32  of the thermal protection end-piece  30  pinched between the pleat  26  and the mechanical protection sheath portion  20  inside the thermal protection end-piece  30 . 
     It will be noted that the force exerted by the expanded sheath portion turned back on itself may cause slight deformation and tightening of the end  32  of the thermal protection end-piece  30 . 
     Thus an unstable equilibrium position is reached in which the mechanical protection sheath  20  has a shorter length in the lengthwise direction X, is retained by the expanded sheath portion, and is turned back on itself over the thermal protection end-piece  30 . As clearly shown in  FIG. 3 , this shortened length of the protection device  10  makes it possible to leave the end of the connection element  11  free and thus to facilitate intervention on the sensor  12  and the connector  15 . 
     The mechanical protection sheath  20  is moreover movable from this unstable equilibrium position to the rest position shown in  FIG. 1  by an elastic return force exerted by the textile structure itself. 
     Thus as soon as the expanded sheath portion  25  is displaced slightly from its unstable equilibrium position, the mechanical protection sheath  20  tends to return to its rest position shown in  FIG. 1 . 
     This effect of returning to the rest position, known as the “push-back effect”, makes it possible to obtain reliable positioning of the thermal protection end-piece  30  over the elements to be protected from heat, i.e. here the sensor  12  and the connector  15 , as shown in  FIG. 1 . 
     Thus fitting the protection device is facilitated and precisely locating the thermal protection end-piece  30  does not depend on manipulations performed by the operator. 
     In practice, the protection device described above may be used for the first fixing of a sensor  12  and its connection element  11  on an automobile vehicle engine  13 . 
     To effect this fixing, the mechanical protection sheath  20  is compressed lengthwise in order to obtain an expanded sheath portion  25  around the connection element  11 . 
     The expanded sheath portion  25  is then turned back on itself by pressing it against the end  32  of the thermal protection end-piece  30  so that it is retained in the unstable equilibrium position shown in  FIG. 3 . 
     In this shortened configuration of the protection device  10 , it is possible to fit the connector  15  without impediment to a connection element, here the sensor  12 . 
     Once the connection manipulations have been carried out, the expanded sheath portion  25  turned back on itself may be released so that the mechanical protection sheath  20  is returned by the elastic return force to the rest position shown in  FIG. 1 . Thus the protection device  10  resumes its initial length and the thermal protection end-piece  30  automatically comes to occupy a dedicated position over the connector  15  in order to protect this sensitive part of the connection element  11  against thermal attack. 
     Of course, the present invention is not limited to the embodiment described above. 
     In particular,  FIGS. 4 to 6  show a different embodiment in which the expanded sheath portion  25  is also adapted to cooperate by being turned back on itself at an end  32  of the thermal protection end-piece, but here inside the thermal protection end-piece. 
     Elements common to the previous embodiment bear the same reference numbers and do not need to be described again in detail. 
     As clearly shown in  FIGS. 5 and 6 , here the expanded sheath portion  25  is adapted to form a pleat  27  inside the thermal protection end-piece  30 . Accordingly, in this second embodiment, the mechanical protection sheath  20  is retained in an unstable equilibrium position by an interior surface  34  of the thermal protection end-piece  30  near its second end  32  keeping the pleat  27  compressed. 
     Moreover, the textile structure of the mechanical protection sheath could be different, and in particular could be produced by a tubular knitting process.