Abstract:
A thermal sleeve for protecting an electronic member connected to a wiring harness, assembly therewith and method of construction are provided. The thermal sleeve includes a tubular heat-settable nonwoven inner layer having a generally cylindrical portion and an outer surface extending along a longitudinal central axis between opposite open ends. A reflective outer layer is disposed about the outer surface. At least one finger of the heat-settable nonwoven inner layer extends radially inwardly from the generally cylindrical portion. The at least one finger is heat-set to remain extended radially inwardly absent an externally applied force thereon. The at least one finger has a free end surrounding a through opening sized for receipt of the wiring harness.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application Ser. No. 62/189,097, filed Jul. 6, 2015, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates generally to tubular sleeve assemblies that provide thermal protection to an electronic object contained therein, and more particularly to a tubular sleeve assembly including a positioning member to maintain the assembly in a selectively releasable, fixed position about the electronic object contained therein. 
     2. Related Art 
     Sensors used in automotive applications, such as oxygen sensors which provide data to control engine operation and performance, are often mounted within the engine compartment of a vehicle where they are subject to harsh environmental elements including intense radiant heat, sources of abrasion and vibration during vehicle operation. Due to the harsh environmental elements, it is advantageous, and in many cases a requirement, to cover the relatively delicate, temperature sensitive sensors with protective sleeving in an effort to dampen vibration, provide protection against abrasion and shield radiant heat from reaching the sensor. Such sleeves generally comprise an elongated, cylindrical tube extending between opposite, open free ends. The cylindrical tube includes a damping inner layer of a nonwoven material, for example, polyester felt and a reflective outer layer comprising, for example, an aluminum foil layer laminated to an outer surface of the inner layer. 
     Due to the configuration of the aforementioned protective cylindrical sleeve and its harsh environment, it is typically difficult to assemble the sleeve about the sensor in a manner which allows the sleeve to be reliably secured and maintained in a desired position, while at the same time being readily removable for servicing of the sensor. Adhesives, tape and interference fits of an entirety of an inner surface of the cylindrical wall of the sleeve are used to effect attachment, but each of these mechanisms suffer various disadvantages. Adhesive attachment of the sleeve about the sensor, while generally secure, at least initially, permanently attaches the sleeve to the sensor, and thus, complicates servicing the sensor at a future time, and in addition, the adhesives can breakdown over time, thereby causing the sleeve to become dislodged from its desired protective position about the sensor. As a result, while generally effective in its initially bonded position, this method does not allow for easy removal of the sleeve for servicing of the sensor or reuse of the sleeve, as it requires destroying the bond joint of the adhesive. In addition, tape and interference fits can be unreliable in view of the heat and vibration encountered within the engine compartment, with tapes further being particularly burdensome to apply, and friction fits of an entirety of a sleeve inner surface suffer from variances in component tolerances, and difficulty of assembly, particularly if the interference is too great, or if the sleeve needs to traverse increased diameter obstacles along the path of assembly, such as a connector, for example. Further mechanisms are also known, such as using end caps made from separate materials from the tubular sleeve to position the sleeve; however, this method requires assembly of multiple components to one another in construction of the sleeve, thereby adding complexity and cost to the manufacture and assembly of the insulative sleeve. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the invention, a thermal sleeve for protecting an electronic member connected to a wiring harness is provided. The thermal sleeve includes a tubular heat-settable nonwoven inner layer having a generally cylindrical portion and an outer surface extending along a longitudinal central axis between opposite open ends. A reflective outer layer is disposed about the outer surface. At least one finger of the heat-settable nonwoven inner layer extends radially inwardly from the generally cylindrical portion. The at least one finger is heat-set to remain extended radially inwardly absent an externally applied force thereon. The at least one finger has a free end surrounding a through opening sized for receipt of the wiring harness. 
     In accordance with another aspect of the invention, the at least one finger includes a plurality of fingers. 
     In accordance with another aspect of the invention, the reflective outer layer can be spiral wrapped about the outer surface. 
     In accordance with another aspect of the invention, the reflective outer layer can be cigarette wrapped about the outer surface. 
     In accordance with another aspect of the invention, the reflective outer layer can be bonded to the outer surface. 
     In accordance with another aspect of the invention, the reflective outer layer extends over the at least one finger. 
     In accordance with another aspect of the invention, a solidified resinous material can be disposed on the nonwoven layer of the at least one finger. 
     In accordance with another aspect of the invention, a rigid layer of material can be bonded to the nonwoven layer of the at least one finger with the nonwoven layer being sandwiched between the reflective outer layer and the rigid layer of material. 
     In accordance with another aspect of the invention, the rigid layer of material can be formed of plastic. 
     In accordance with another aspect of the invention, the at least one finger can include a plurality of fingers and the rigid layer of material can be formed having a plurality of slits aligned with spaces between the fingers. 
     In accordance with another aspect of the invention, the at least one finger can be provided as a single finger having a plurality of overlapping folded regions. 
     In accordance with another aspect of the invention, a method of constructing a sleeve for protecting an electronic member connected to a wiring harness is provided. The method includes forming a tubular heat-settable nonwoven inner layer having a generally cylindrical portion and an outer surface extending along a longitudinal central axis between opposite open ends; fixing a reflective outer about the outer surface; and heat-setting at least one finger of the heat-settable nonwoven inner layer to extend radially inwardly from the cylindrical portion and establishing a through opening with a free end of the at least one finger for receipt of the wiring harness in an interference fit therein. 
     In accordance with another aspect of the invention, the method can further include forming a plurality of the at least one finger. 
     In accordance with another aspect of the invention, the method can further include forming the plurality fingers after the heat-setting step. 
     In accordance with another aspect of the invention, the method can further include forming the plurality fingers before the heat-setting step. 
     In accordance with another aspect of the invention, the method can further include establishing the through opening after heat-setting the at least one finger. 
     In accordance with another aspect of the invention, the method can further include disposing a resinous layer on the heat-settable nonwoven inner layer of the at least one finger. 
     In accordance with another aspect of the invention, the method can further include sandwiching the nonwoven layer of the at least one finger between the reflective outer layer and an inner rigid layer of material. 
     In accordance with another aspect of the invention, the method can further include forming the inner rigid layer of material having generally the same shape as the at least one finger. 
     In accordance with another aspect of the invention, the method can further include forming the inner rigid layer of material from plastic. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description of presently preferred embodiments and best mode, appended claims and accompanying drawings, in which: 
         FIG. 1A  is a schematic side view of an assembly constructed in accordance with one aspect of the invention for protecting an electrical component; 
         FIG. 1B  is a schematic side view of an assembly constructed in accordance with another aspect of the invention for protecting an electrical component; 
         FIG. 2A  is a schematic isometric view of the thermal sleeve in accordance with one aspect of the invention of  FIGS. 1A-1B  shown in a partially constructed state; 
         FIG. 2B  is a schematic isometric view of the thermal sleeve in accordance with another aspect of the invention of  FIGS. 1A-1B  shown in a partially constructed state; 
         FIG. 2C  is a schematic isometric view of the thermal sleeve in accordance with another aspect of the invention of  FIGS. 1A-1B  shown in a partially constructed state; 
         FIG. 2D  is a partial cross-sectional end view of the thermal sleeve in accordance with another aspect of the invention of  FIGS. 1A-1B ; 
         FIG. 3  is an isometric view of the assembly looking generally along the arrow  2  of  FIG. 1A ; 
         FIG. 3A  is a partial cross-sectional side view of the thermal sleeve and elongate member of  FIG. 3  showing a finger in phantom as it deflects axial during relative sliding movement between the thermal sleeve and elongate member; 
         FIG. 4  is an isometric end view of the thermal sleeve of  FIG. 2A  shown in a finished state; 
         FIG. 5A  is an isometric view of an opposite end of the thermal sleeve of  FIG. 4 ; 
         FIG. 5B  is view similar to  FIG. 5A  of the thermal sleeve of  FIG. 2B  shown in a finished state; 
         FIG. 5C  is view similar to  FIG. 5A  of the thermal sleeve of  FIG. 2C  shown in a finished state; 
         FIG. 6  is a cross-sectional view of a thermal sleeve constructed in accordance with yet another aspect of the invention; and 
         FIG. 7  is a plan view of a support member of the thermal sleeve of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring in more detail to the drawings,  FIGS. 1A-1B  each show an assembly  10 , including a thermal protective sleeve including an integral position member, referred to hereafter simply as sleeve  12 , constructed in accordance with one aspect of the invention. The sleeve  12  is used, as least in part, to protect an electrical member  14  contained at least in part therein, such as sensor, against the effects of extreme radiant heat, abrasion, contamination and vibration. The sensor  14  is shown connected to an end of a wire harness  16  on an engine component  18  of a vehicle. The wire harness  16  can be provided as a bundle of exposed, insulated wires, or as a bundle of insulated wires enclosed within an outer protective sleeve, also referred to as tube  20  ( FIG. 1A ),  20 ′ ( FIG. 1B ), wherein the tube  20 ,  20 ′ can have a corrugated or convolute outer surface  22  ( FIG. 1A ), or generally smooth outer surface  22 ′ ( FIG. 1B ), by way of example and without limitation. The sleeve  12  is configured for slidable movement along a longitudinal axis  24  of the wire harness  16  and tube  20 ,  20 ′, if provided, to bring the sleeve  12  into its desired protective position about the sensor  14 . The sleeve  12  is further configured, via an integral positioning member made as one-piece of material with the sleeve  12 , as discussed in further detail below, to remain fixed in the protective position until desired to selectively slide the sleeve  12  away from its protective position, such as may be desired to service the sensor  14 . The sleeve  12  remains in its protective position during use via frictional engagement of the positioning member with the wires  16  or tube  20 ,  20 ′ thereof, without need of secondary fasteners, such as tape or adhesives, and thus, assembly  10  is made simple and cost effective. 
     The sleeve  12  can be constructed having any desired length. The sleeve  12 , as shown in partially constructed embodiments of  FIGS. 2A-2C  and respective finished embodiments of  FIGS. 5A-5C , has a nonwoven inner layer  26  and a reflective outer layer  28 . The inner layer  26 , in accordance with one aspect of the invention, is constructed of a heat-formable nonwoven material, and can be constructed having any desired wall thicknesses (t), depending on the nature and severity of heat exposure in the intended environment. The nonwoven material forming the inner layer  26  is formed including heat-settable fibers, such as heat-settable low melt fibers including either monofilaments and/or bi-component fibers. The low melt fibers can be mixed with standard thermoplastic fibers and/or fiberglass and/or natural fibers of hemp, jute, Keflex, or the like. The low melt fibers at least partially melt at a temperature lower than the remaining fibers when heat treated in a heat-setting process, whereupon the low melt fibers take on a solidified, heat-set configuration, thereby biasing the inner layer  26  and outer layer  28  to take on and retain a heat-set shape. If bi-component fibers are provided as low melt fibers, they can be provided having a core of a standard thermoplastic material, such as polyethylene terephthalate (PET), for example, with an outer sheath of polypropylene, polyethylene, or low melt polyester, for example. The standard thermoplastic fibers can be provided as any thermoplastic fiber, such as nylon or PET, for example, and act in part to provide the desired density and thickness (t) to the inner layer  26 , as desired, thereby providing additional thermal protection and rigidity to the sleeve  12 , while also being relatively inexpensive compared to the heat-settable fibers. Accordingly, the inner layer  26  is constructed having a suitable thickness (t) and density of mechanically intertwined, or otherwise bonded, non-woven standard thermoplastic fibers and low melt fibers to obtain the desired physical properties, depending on the application, while also being heat-settable into a desired shape. 
     The outer layer  28  is provided to reflect extreme radiant heat typical of an engine compartment, including temperatures generated by an exhaust system. The outer layer  28  can be formed of any suitable metal material, including a foil layer of aluminum or other desired metals. The foil outer layer  28  is relatively thin, thereby allowing the sleeve  12  to remain flexible over meandering paths and corners. The outer layer  28  is disposed about an outer surface  27  of the inner layer  26 , and can be spiral wrapped or cigarette wrapped about the nonwoven inner layer  26 , as desired. Any suitable, heat resistant adhesive can be used to facilitate bonding the outer layer  28  to the inner layer  26 , if desired. 
     In accordance with one presently preferred method of constructing the sleeve  12 , the nonwoven inner layer  26  is formed as a circumferentially continuous tubular wall, such as by being spiral wrapped, wherein the opposite edges can be brought into flush abutting relation with one another, thereby forming a butt joint  25  ( FIG. 2D ), to form smooth cylindrical outer and inner surfaces  27 ,  29  extending between opposite open ends  30 ,  32 . Then, the foil outer layer  28  can be wrapped about, in spiral or cigarette fashion, wherein the foil layer  28  can have opposite edges  33 ,  35  brought into overlapping relation with one another, and can be mechanically fixed or bonded to the outer surface  27  of the inner layer  26 . Then, integral fingers  34 , also referred to as positioning members, end projections or locating and retention features, can be formed. In one embodiment, the fingers  34  can be formed in a cutting operation, whereupon some of the inner layer  26  and outer layer  28  is cut via any suitable cutting process to form slits or spaces  36  between adjacent fingers  34 . The spaces  36 , by way of example and without limitation, are shown as being generally V-shaped in  FIG. 2A , though any desired shaped can be formed, thereby facilitating a subsequent folding operation, wherein the fingers  34  are folded radially inwardly to point generally toward one another and subsequently heat-set ( FIGS. 3, 4, 5A ). For example, as shown in another embodiment, rather than having V-shaped notches formed between adjacent fingers  34 , the slits  36  can be formed as straight or substantially straight slits ( FIG. 2B ), thereby forming generally rectangular fingers  34 , whereupon the fingers  34  can then be folded radially inwardly and subsequently heat-set ( FIG. 5B ). In this embodiment, it can be seen that the individual fingers  34  overlap one another along their radially extending edges, which can further act to provide enhanced protection to the sensor  14 . Further yet, rather than forming slits or otherwise cutting the sleeve wall to form individual fingers, a desired uncut length (L;  FIG. 2C ) of an end region of the sleeve wall can be folded radially inwardly without first cutting or slitting, whereupon a single, circumferentially extending finger  34  can be formed, having accordion-like, folded overlapping regions as a result of not having slits ( FIG. 5C ). The folding operation can be performed by first disposing the tubular wall on a mandrel, and then folding the plurality of fingers  34  or single finger  34 , depending on the construction desired, over an end of the mandrel to bring the inner layer  26  into abutment with a generally flat end of the mandrel. Then, with the finger(s)  34  in the folded position, sufficient heat can be applied to the inner layer  26  to cause the inner layer, at least within the region including the finger(s)  34 , to take on a heat-set. The heat can be applied via a heatable mandrel and/or via an external source of heat. Accordingly, the finger(s)  34  are heat-shaped to remain or substantially remain in the “as folded” position, thereby providing the sleeve  12  with a remaining cylindrical portion extending from one end  30  to the location, a newly formed end  32 ′ of the cylindrical portion of the sleeve  12 , where the finger(s)  34  are bent radially inwardly. In accordance with another aspect of the invention, as shown in  FIGS. 5A-5C , it is contemplated that a resinous material RM could be applied to the inner layer  26 , at least on the region of the inner layer  26  forming the fingers  34 , or to the entirety of the inner layer  26 , if desired, to facilitate providing the material of the fingers  34  with the desired stiffness, rigidity, resiliency and flexibility desired to optimally function as retention and retaining members. Further yet, as shown in  FIGS. 6 and 7 , a separate support member in the form of a reinforcing layer of material, such as a plastic material, by way of example and without limitation, of desired thickness, resiliency and flexibility, such as a generally circular disc  38 , having through opening  40  sized and shaped similarly to an opening  42  formed by free ends  44  of the fingers  34 , could be bonded inside the sleeve  12  in abutment with the inner layer  26  of the fingers  34 . If provided, it is contemplated that the circular disc  38  would have slits  46  formed therein, as shown, with the slits  46  being arranged to register in axially and radially aligned relation with the slits or spaces  36  to allow the fingers  34  to remain resiliently flexible axially inwardly and axially outwardly along the axis  24  during assembly and removal of the sleeve  12  along the wire harness  16 . Of course, it should be recognized the slits  46  can be formed to take on the same shape as the slits  36  formed between the fingers  34 , as desired. 
     Upon completing the heat-setting operation, the sleeve  12  can be removed from the mandrel, wherein the one-piece sleeve  12  is provided, without having to fasten other components thereto in secondary operations, having a cylindrical portion extending from the open end  30  to an end location  32 ′ where the fingers  34  are folded radially inwardly, without need of secondary fasteners to join the fingers  34  to the sleeve  12 . 
     In use, the sleeve  12  can be easily slid over the wire harness  16  or tube  20  thereof, whereupon ends  44  of the fingers  34  engage and flex axially against the wires harness  16  or tube  20 . A predetermined amount of friction and interference between the finger end(s)  44  and the wire harness  16  or tube  20  can be provided by sizing the opening  42  bounded by the finger end(s)  44  in construction. As shown generally in  FIG. 3A , with the fingers  34  being flexible and resilient, the fingers  34  are readily biased slightly axially via friction or interference with the wire harness  16  or tube  20  to flex axially away from the sleeve end  30  during installation and axially toward the sleeve end  30  during removal, such as may be required in service. If a tube  20  is provided as a corrugate tube ( FIG. 1A ), the fingers  34  can be biased to flex axially over annular crests C during installation and removal, and can be constructed to take on a predetermined thickness to be received within annular valleys V of the corrugations to facilitate maintaining the sleeve  12  in its intended “in use” position about the sensor  14 . 
     In  FIG. 5C , a sleeve  112  constructed in accordance with another aspect of the invention is shown, wherein the same reference numerals, offset by a factor of  100 , are used to identify like features. The sleeve  112  has an inner layer  126  and an outer layer  128  constructed of the same materials discussed above for the sleeve  12 . In contrast to the sleeve  12 , a single finger  134  is folded radially inwardly, however, the free end  144  of the finger  134 , rather than forming an opening for receipt of the wires  16  or tube  20  as folded, can be formed via a subsequent cutting operation, such as die cutting via a circular punch, or any desired outer peripherally shaped punch. As such, the through opening  142  can be formed having a precisely sized and shaped configuration, whether circular or other configuration, thereby resulting in a precision amount of interference between a free end  144  of the finger  134 . As such, it should be recognized that a single, circumferentially continuous finger  134  can be folded radially inwardly, and then the opening  142  can be cut. Of course, this same mechanism for form the central opening can be used if a plurality of fingers  134  are formed and folded radially inwardly. If a single finger  134  is formed, the finger  134  has a plurality of overlapping folded regions  50  formed by the material of the finger  134 . Further yet, it is contemplated that upon folding the single finger  134  or plurality of fingers  134  radially inwardly, the finished shape of individual fingers  134  can be subsequently formed in a cutting operation, in addition to the cutting operation used in forming the opening  142 . 
     Obviously, in light of the above teachings, many modifications and variations of the present invention are possible. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.