Patent Publication Number: US-7913470-B2

Title: Insulating strip for supporting a composite structure

Description:
CROSS-REFERENCE 
     The present application claims priority to German utility model application number 20 2007 004 935.8 filed Apr. 2, 2007, German utility model application number 20 2007 009 106.0 filed Jun. 28, 2007 and German utility model application number 20 2007 016 649.4 filed Nov. 27, 2007, all of which are incorporated herein by reference as if fully set forth herein. 
     TECHNICAL FIELD 
     The present invention relates to insulating or separating strips that may be utilized, e.g., to separate and position two profiles or frames of, e.g., a window, a door or a façade. In a preferred embodiment, the insulating or separating strip may provide a shear-resistant connection of the two profiles or frames, even when the respective profiles or frames are subjected to different temperature environments. 
     BACKGROUND 
     In recent years, the use of double pane or double profile structures has become more common in order to substantially reduce heat transfer through, e.g., window, doors, façades and other building structures. Typically, such structures include an outer metal profile or frame, an inner metal profile or frame and one or more insulating strips or struts for maintaining the inner and outer profiles or frames in a spaced relationship. In addition, such insulating strips or struts are often made of a material exhibiting low conductivity in order to substantially minimize heat transfer from a warm side to a cold side of the composite structure. 
     However, as discussed in U.S. Pat. No. 6,035,600, in the event that one of the metal frames is subjected to a significantly different temperature environment than the other, thermal expansion of the warmer frame results in a displacement force between the respective frames of the composite section. As a result, the composite structure may bend or flex due to relative longitudinal displacement of the respective frames. This is known in the art as a “bimetal effect”, although it is not necessary for the frames to be comprised of different metals. Rather, it only refers to the different thermal expansions of the metal frames caused, e.g., by the metal frames being at different temperatures. 
     Heat sources causing a unilateral temperature rise include, e.g., temperature differences between a room interior and the outside air (e.g., in winter) or incident solar radiation upon the outer frame (e.g., in summer) that causes the temperature of the outer frame to rise due to absorption of solar energy. The resulting deformation of the composite structure causes an arching that may impair the function of the window, door or façade element. U.S. Pat. No. 6,035,600 proposes an insulating rod for connecting frames that is purported to provide a slight resistance to such relative longitudinal displacement. 
     German Patent No. 199 56 415 C1 discloses another solution to this longitudinal displacement problem. Two longitudinal edges of an insulating profile are connected by a substantially U-shaped outer bridge. The two longitudinal edges are respectively fitted to the outer and inner metal frames of a window, door or façade element. The insulating profile is preferably made of a synthetic material, such as polyamide, polyester or polypropylene, and has a Young&#39;s modulus of greater than 2,000 N/mm 2 . The U-shaped bridge imparts a sheer-resistant connection between the inner and outer frames and resists relative longitudinal displacement in the event that the inner and outer frame are subjected to different temperature environments. 
     German Patent Publication No. 198 53 235 A1 discloses an alternate solution to this problem. In certain embodiments thereof, the insulating strip has a ladder-like structure, wherein a plurality of rungs or bars extend between respective longitudinal edges adapted to be connected to respective inner and outer metal frames of a window, door or façade. The openings between the rungs may have a circular-shape, a rectangular-shape, an oval-shape or a slot-shape. The insulating profile may be co-extruded using two materials having different hardness, such that the inner rungs exhibit an increased elasticity as compared to the longitudinal edges. This design purports to minimize or prevent bending or deflection of the two sides of the composite profile due to temperature differences. In order to prevent the penetration of moisture and/or dust through the openings, this reference recommends covering the openings with a film, a sealing tape or a dipping varnish. 
     An insulating strip having a metal insert embedded in plastic is also known from DE 198 18 769. This insulating strip also has openings that impart a ladder-like structure to it. The openings may be square-shaped, rectangular-shaped or substantially triangular-shaped. The openings in the metal insert are intended to reduce thermal conduction and the metal insert serves to prevent a complete failure or collapse of the insulating strip in the event of a fire. 
     SUMMARY 
     However, there remains in the art a need to provide improved insulating strips or struts, which may be utilized, e.g., in composite structures, such as composite profiles or frames. In certain representative embodiments, such insulating strips or struts exhibit relatively high shear strength while still providing improved thermal isolation and reduced risk of contamination of the interior portion of the composite structure. 
     In one aspect of the present teachings, an insulating strip may be designed, e.g., for a window unit, a door unit, a façade unit and/or another type of architectural unit, or any other unit that is generally comprised of two frames or profiles supported in a spaced relationship relative to each other. 
     The insulating strip preferably has a body portion extending in a longitudinal direction (Z) and includes at least two longitudinal edges separated by a distance (a) in a transverse direction (X). The longitudinal edges are preferably configured or constructed for a shear-resistant connection with profiled or shaped components of the respective frames or profiles, such as the above-noted architectural units. 
     The insulating strip preferably has openings that penetrate through one or more walls of the body in a height-direction (Y) of the insulating strip. The openings are preferably separated from each other in the longitudinal direction (Z) by struts, bars, strips, supports, etc. These structures may, in certain embodiments, give the insulating strip an overall ladder-shaped appearance in plan view. However, in other embodiments, the openings in the insulating strip may be circular, oval, hexagonal, i.e. other than square or rectangular, without departing from the scope of the present teachings. 
     The insulating strip preferably includes a connecting element or structure configured to attach a covering element or profile thereto. Such a covering element may serve to cover the openings in the insulating strip, thereby preventing contamination from entering into the interior space defined between the two frames or profiles of the assembled composite structural unit. 
     In a further preferred embodiment, the covering element or profile is integrally formed with the insulating strip and includes a clip element configured to detachably connect with a terminal portion of the covering profile or element. Such covering profiles or covering sheets preferably cover the intervening spaces or openings between the rungs, struts. 
     The covering profiles or covering sheets can, for example, be clipped on, adhered to, extruded on, laminated to, etc., the insulating strip body. The covering profiles/sheets may be either integral with the insulating strip body or a separate piece. 
     Such covering profiles may, on the one hand, serve to prevent moisture from penetrating into a space or gap between the frames of the assembled composite structural unit. In addition or in the alternative, the covering profiles may also protect the inner core. The covering profiles or covering sheets can be attached to the frames before or after the assembly of the units. Decorative elements can also be attached thereto. 
     In a further aspect of the present teachings, one or more clip heads may project from at least one side of the insulating strip in the height-direction (Y). In addition or in the alternative, one or more clip retainers may also extend in the height-direction (Y), preferably from an opposite side of the insulating strip. The clip retainer(s) preferably define(s) a recess configured to receive and retain the clip head(s). These clip heads and clip retainers may preferably serve to clip-fit or snap-fit a covering element or profile onto the insulating strip, thereby securely covering the openings in the insulating strip. 
     In a further aspect of the present teachings, the covering profile may be in situ extruded together with the insulating strip body and may be configured to be bent over the insulating strip so as to cover one side of the openings. A portion of the covering profile is further preferably configured to be clipped or otherwise connected to the insulating strip body, thereby securing the covering profile in a position that covers the openings in the insulating profile. 
     In a further aspect of the present teachings, the covering profile may be separate from the insulating strip body and may optionally have a width in the transverse direction that is less than the width of the insulating strip body. In this case, the covering profile may include clip heads and/or clip retainers that is/are complementary to the clip heads and/or clip retainers defined on the insulating strip, as was indicated above. In addition or in the alternative, the covering profile may include abutment lips extending in the longitudinal direction (Z), which abutment lips are configured to contact the insulating strip body. More preferably, the abutment lips are designed to contact the insulating strip body so as to seal the openings in the insulating strip body from the outside environment. 
     In a further aspect of the present teachings, a composite profile may include first and second window, door or façade frames with at least one insulating strip or strut disposed therebetween for supporting the two frames in a spaced relationship. More preferably, the frames are connected by the insulating strip(s) in a shear-resistant manner, such that the frames remain connected and supported, even if one frame is subjected to a significantly temperature environment than the other frame. The insulating strip is preferably constructed so that a warmer frame is permitted to expand and displace relative to a cooler frame, while avoiding an overall bending or deflection of the assembled composite structural unit. In another embodiment, the insulated strip is preferably constructed in order to apply a spring or elastic force that resists relative longitudinal displacement of the frames, in the event that frames are disposed in different temperature environments. In all embodiments, the insulating strips or struts are designed to minimize or prevent the so-called “bimetal effect”, such that the frames of the assembled composite structural unit do not bend, deflect, deviate, etc. when the frames are situated in different temperature environments. 
     The term “insulating strip” as utilized herein may be substituted or replaced with a variety of other terms, such as insulating bar, isolating strip, isolating bar, separating support, separating bar, insulating strut, isolating strut, separating strut, etc. These various terms may be employed interchangeably unless otherwise indicated. Generally speaking, such structures preferably include the properties of providing a supporting function between two frames, profiles or composite structures and also reduce or minimize heat transfer across the structure when the frames, profiles, composite structures connected thereby are situated in different temperature environments. 
     In more preferred embodiments, such structures are preferably adapted to resist longitudinal distortion when the respective frames, profiles or composite structures are subjected to differing temperature environments. Thus, when at least one insulating strip according to this aspect of the present teachings is utilized to join or connect, e.g., two metal frames, thereby forming a composite profile, movement of the frames relative to each other in the longitudinal direction can be limited and/or prevented by the high shear-resistance strength of the insulating strip(s). The sheer-resistance can be determined by suitably selecting the characteristics, properties and dimensions of the insulating strips, such as the width, thickness, length, number, etc. of the connecting struts or bridges within each insulating strip, as well as by appropriate selection of the material(s) forming the insulating strip. 
     In an advantageous manufacturing method, the insulating strips are first formed from a suitable material, e.g., by extrusion, as profiled components having a constant cross section over the entire length. Thereafter, the rungs or struts or bridges of the insulating strip are manufactured to form openings in the insulating strip by a subsequent processing such as machining (e.g. milling), cutting (such as e.g., laser cutting, water jet cutting, etc.), punching, etc. The removed material can be recycled. 
     Preferably, the components of the unit, e.g., window frames, door frames, façade frames, etc., are firmly and undetachably or permanently connected via the insulating strip(s). 
     In addition or in the alternative, the intervening spaces or opening between the rungs, struts, bars, etc. of the insulating strip may optionally be filled with a material that has a lower thermal conduction coefficient than the material of the rungs and/or insulating strip. 
     In addition or in the alternative, the covering profile/element may be electrically-conductive. In this case, the covering profile/element can take on the color of the metal profiles, e.g., by employing a powder coating step to paint the covering profile and/or the assembled composite structural unit. Staining of the insulating profile and/or covering profile/element is also possible. 
     One advantage of such an embodiment is that k-values (thermal conductivity properties) of the insulating strips are not unduly diminished by the attachment of the covering sheets/covering profiles/fillings, in particular the covering profiles. 
     Further features and advantages will result from the description of exemplary embodiments with the aid of the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a first embodiment of an insulating strip;  FIG. 1   a  shows a plan view,  FIG. 1   b  shows a cross-sectional view perpendicular to the longitudinal direction along line B-B in  FIG. 1   a , and  FIG. 1   c ) shows a cross-sectional view perpendicular to the longitudinal direction along line C-C in  FIG. 1   a.    
         FIGS. 2   a - 2   c  show a second embodiment of an insulating strip having different rung widths in views corresponding to  FIG. 1 . 
         FIG. 3  shows a cross-sectional view perpendicular to the longitudinal direction of an insulating strip when being connected with an inner profile component and an outer profile component by crimping. 
         FIG. 4  shows a third embodiment of an insulating strip having meander-shaped rungs in a ladder-like structure. 
         FIG. 5  shows a fourth embodiment of an insulating strip having an in situ extruded cover, which view corresponds to  FIG. 1   c.    
         FIG. 6  shows a modification of the fourth embodiment of  FIG. 5 . 
         FIG. 7  shows a fifth embodiment of an insulating strip;  FIG. 7   a  shows a cross-sectional view perpendicular to the longitudinal direction of the insulating body,  FIG. 7   b  shows a cross-sectional view perpendicular to the longitudinal direction of a to-be-clipped-on covering profile, and  FIG. 7   c  shows the assembled state of two metal profiles with an insulating strip and covering profile disposed therebetween, in a cross-sectional view perpendicular to the longitudinal direction. 
         FIGS. 8   a - 8   c  show a sixth embodiment of an insulating strip, wherein  FIG. 8   a  shows a plan view perpendicular to the longitudinal direction,  FIG. 8   b  shows a cross-sectional view perpendicular to the longitudinal direction,  FIG. 8   c  show a modification of the sixth embodiment in a cross-sectional view perpendicular to the longitudinal direction. 
         FIG. 8   d  shows a seventh embodiment in a plan view perpendicular to the longitudinal direction. 
         FIG. 8   e  shows an eighth embodiment in a plan view perpendicular to the longitudinal direction. 
         FIG. 8   f  shows a ninth embodiment in a plan view perpendicular to the longitudinal direction. 
         FIG. 9  shows a tenth embodiment of an insulating strip, wherein  FIG. 9   a  shows a plan view perpendicular to the longitudinal direction and  FIG. 9   b  shows a cross-sectional view perpendicular to the longitudinal direction. 
         FIG. 10  shows an eleventh embodiment of an insulating strip, wherein  FIG. 10   a  shows a plan view perpendicular to the longitudinal direction,  FIG. 10   b  shows a cross-sectional view perpendicular to the longitudinal direction,  FIG. 10   c  shows a modification of the cross-sectional shape perpendicular to the longitudinal direction,  FIG. 10   d  shows a cross-sectional view without openings,  FIG. 10   e  shows the embodiment of  FIG. 10   b  with filling material, and  FIG. 10   f  shows the embodiment of  FIG. 10   c  with filling material. 
         FIGS. 11   a - 11   f  show modifications of the sixth to ninth embodiments in views corresponding to  FIG. 8 . 
         FIG. 12   a  shows a modification of the embodiments of  FIGS. 10   a  and  10   c.    
         FIGS. 12   b  and  12   c  show modifications of the embodiments of  FIGS. 8 and 11 , respectively. 
         FIG. 12   d  shows a modification of the embodiment of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the insulating strips shown in  FIGS. 1 and 2 , the rungs  23  of a ladder-shaped insulating strip body  20  extend between the continuous longitudinal edges  21 ,  22  transverse to the longitudinal direction Z. However, the rungs  23  can also extend in an inclined manner (e.g., up to about 20°) relative to the transverse direction. The rungs  23  can also have a curved shape in certain embodiments. Preferably, but not necessarily, all rungs  23  may have the same shape. 
     In the present disclosure, the rungs  23  may also be referred to as struts, bars, supports, braces, stanchions, stays, etc., which terms are interchangeable in the structures according to the present teachings. In effect, the present teachings are directed to any structure that provides support between two essentially-parallel-extending edges or rails  21 ,  22  with intervening spaces or openings  24  formed therebetween. 
     The longitudinal edges or borders  21 ,  22  are preferably configured or shaped to be fitted with respective profiled components  31 ,  32  (see  FIG. 3 ) of a composite profile for a shear-resistant connection in the longitudinal direction z. Representative, but not limiting, examples of the profiled components  31 ,  32  include window, door or façade elements or frames, or any other architectural units, which may comprise metal in certain embodiments. The profiled component may be a composite structure that includes, e.g., a metal frame surrounding a glass insert. In addition or in the alternative, the profiled component may include a wood frame and/or wood insert and/or a plastic frame and/or a plastic insert, etc. 
     In the embodiments of  FIGS. 1-3 , the longitudinal edges or borders  21 ,  22  are formed as crimped heads  25  or crimped projections for being crimped within grooves or retainers formed in the profile components  31 ,  32 . The grooves or retainers may be each formed, e.g., by a bendable projection  33  and an opposing wall segment  34 . Other types of connections, such as adhering, form-fitting, friction-fitting, etc., are also possible and are within the scope of the present teachings. 
     In the plan views of  FIGS. 1   a  and  2   a , the rungs  23  have a width b in the longitudinal direction z, which is selected in accordance with the required transverse tensile strength and the required transverse stiffness, as well as the material utilized to form the rungs  23  and the insulating strip body  20 . Representative, but not limiting, rung widths b may fall within the range of 0.5 to 10 mm, preferably 1 mm to 5 mm, and more preferably 1 mm to 3 mm. 
     In a cross-sectional view perpendicular to the longitudinal direction shown in  FIGS. 1   b  and  2   b , the rungs  23  have a height (thickness) h in the y-direction, which also may be selected in accordance with the required transverse tensile strength and the required tensile stiffness, as well as the material utilized to form the rungs  23  and the insulating strip body  20 . Representative, but not limiting, rung heights h may fall within the range of 0.5 to 10 mm, preferably 0.5 mm to 5 mm, and more preferably 0.7 to 2 mm. 
     The rungs  23  are disposed in the longitudinal direction z, preferably but not necessarily with constant intervals or spacings d therebetween. Representative, but not limiting, intervals or spacings d may fall within the range of 1 mm to 100 mm, preferably 1 mm to 50 nm, more preferably 1 mm to 5 mm, and most preferably 1 mm to 3 mm. Naturally, other widths, thicknesses, lengths and intervals are also possible in accordance with the specifications of the intended use of the insulating strip  10 . 
     Test results were obtained based upon ladder-like insulating strips  10  having rungs  23  that, in the plan view in the longitudinal direction of the insulating strip, have a width b of 1 mm for a first embodiment and a width b of 3 mm for a second embodiment and, in the longitudinal direction of the insulating strip, each have constant intervals d of 3 mm. In the plan view in the transverse direction to the longitudinal direction of the insulating strip, the openings  24  had a length c of about 14 mm with an overall size or width a of the insulating strip  10  in the x-direction of about 23 mm. These insulating strips exhibited values for the transverse tensile strength (tension in the direction of the connection of the profile components connected by the insulating strip, i.e. the x direction in  FIGS. 1 and 2 ), which were higher for both rung widths than for comparable profiles according to DE 199 56 415 C1. In addition, the sheer-resistance (relative displacement of the profile components connected by the insulating strip in the longitudinal direction z of the profile components, i.e. in the longitudinal direction z in  FIGS. 1 and 2 ) could be adjusted simply by setting the rung width to values below or above the values for comparable profiles according to DE 199 56 415 C1. Consequently, the amount of the longitudinal displaceability is easily tailorable for a very high transverse tensile strength. These strips were designed to provide a limited longitudinal displaceability in order to reduce the problem of the “bimetal effect” discussed above in the Background section. 
       FIG. 4  shows a third embodiment of an insulating strip  10  with meander-shaped rungs  23  of the ladder-like structure in a view corresponding to  FIG. 1   a , wherein the same reference numerals represent the same structures as  FIGS. 1-3 . This embodiment is also capable of minimizing relative longitudinal displacement between frames of a window, door, façade, etc. 
     In the fourth embodiment of an insulating strip shown in  FIG. 5 , an in situ extruded cover or covering profile  40  is provided for covering the intervening spaces  24  between the rungs  23 . The embodiment of  FIG. 5  is shown in a view similar to  FIGS. 1   c  and  2   c  and may be mounted between profiled components  31 ,  32  by crimping the crimping heads  25  in the manner shown in  FIG. 3 . 
     The covering profile  40  of  FIG. 5  is integrally formed, e.g., by in situ extruding it with the insulating strip body  20 . In the cross-sectional view perpendicular to the longitudinal direction z shown in  FIG. 5 , the covering profile  40  is extruded so as to extend from one side of the rungs  23  as viewed in the x-direction. The free or terminal end (edge) of the covering profile  40  is clipped onto the other side of the rungs  23  as viewed in the x-direction. The clip connection is formed such that the clipping takes place in the height-direction, i.e. the y-direction. 
     The structure of the connecting arrangement may be selected according to the specifications for the intended use of the insulating strip. For example, in  FIG. 5 , a snap-fit connection is shown, wherein the covering profile  40  includes a clipping head that elastically-resiliently fits into a clipping retainer formed adjacent the crimping head  25 . However, other types of snap-fit, form-fit, friction-fit connections are possible, as well as other types of connections, such as adhesives, fasteners, etc. are within the scope of the present teachings. In the embodiment of  FIG. 5 , it only significant that the covering profile  40  is integrally manufactured with the insulating strip body  20  and then is bent or folded over so as to cover the openings  24 . The form or type of the connection for holding the covering profile  40  in the position covering/protecting the openings  24  is not particularly limited. 
     In an alternative embodiment shown in  FIG. 6 , the clip connection is formed differently, such that the clipping takes place inclined to the height-direction (y-direction) and a traction force in the transverse direction (x-direction) holds the clip in engagement. In this embodiment, the covering profile  40  is shown extending over a rung  23  and the rung  23  may have a different thickness or height h 1  than the thickness or height h 2  of the covering profile  40 . 
     In the fifth embodiment shown in  FIG. 7   a , clip heads  28 , e.g., male clip components, may be provided on one or more rungs  23  of the insulating strip body  20 . As a representative, non-limiting example, the clip heads  28  may be disposed such that, in the height-direction y, one clip head  28  is disposed on one side and two clip heads  28  are disposed on the other side of the body  20 . The single clip head  28  may be disposed centrally on the rung  23  in the transverse direction x, while the two other clip heads  28  on the other side may be disposed at an identical distance from the center. However, various other arrangements of the clip heads  28  may be utilized, as will be apparent from the following teachings. 
     In  FIG. 7   b , a cover or covering profile  40  may be provided, e.g., with three clip retainers  48 , e.g., female clip components. The two outer clip retainers  48  may be provided at the same distance as the two clip heads  28  located on one side of the insulating strip body  20 . The third clip retainer  48  is disposed centrally between the outer clip retainers  48 . 
     As is readily apparent from  FIGS. 7   a - 7   c , a cover or covering profile (element)  40  can be clipped onto one or both sides of the insulating strip body  20  without the need for providing differently-configured covers  40 . However, if desired, it is also within the present teachings to provide two different covers  40 , each having different numbers or arrangements of clip retainers  48 . Naturally, it is also within the present teachings to provide the clip head(s)  28  on the cover  40  and the clip retainer(s)  48  on the insulating strip body  20 . Moreover, although a snap-fit connection is shown herein as an exemplary embodiment, other forms of connections are possible, as were discussed above. 
     The insulating strip body  20  may have a substantially constant thickness h 1  over its width a 1  in the transverse direction x. The width a 2  of the cover  40  in the transverse direction x may preferably be less than or equal to the width a 1  of the insulating strip body  20 . In this preferred embodiment, the edges of the cover  40  may also include two abutment lips  42  formed substantially in the transverse direction x and extending substantially in the longitudinal direction Z. The clip retainers  48  may be formed to have a recess of depth h 4  in the height-direction y, as measured from the base of the clip retainer  48  to the outermost tip of the clip retainer  48 . The depth h 4  is preferably less than the height h 3  of the clip heads  28 . The lips  42  end in the height-direction y at the peak or terminal end of the clip retainers  48  or somewhat higher, as shown e.g., in  FIG. 7   c.    
     In addition, as shown in  FIG. 7   c , the abutment lips  42  may extend from the body  41  of the cover  40  at an angle, e.g., of between 90-135°, more preferably between 100-120°. The ends of the abutment lips  42  may preferably contact and form a seal between the cover  40  and the insulating strip body  20  when connected thereto. 
     Although the cover  40  is preferably detachably coupled to the insulating strip body  20 , it may also be permanently or fixedly connected to the insulating strip body  20  in certain embodiments of the present teachings. It is simply preferable that the cover  40  serves to cover and/or seal the openings  24  from the outside environment, so that moisture and/or dirt do not penetrate into the interior cavity of the fully-assembled composite structure, e.g., a double-pane window unit, door unit, etc. 
     Preferably, synthetic material having a Young&#39;s modulus value greater than 2000 N/mm 2  is used to form the insulating strip  10 . Suitable synthetic materials include, but are not limited to, polyamides, polyesters or polypropylenes, e.g., PA66 (Polyamide 66). The covering profile  40  may optionally be formed from a different material than the insulating strip body  20 . 
     The thickness h 1  of the insulating strip bodies  20  of all embodiments may optionally fall within the range of 1 mm to 50 mm, preferably 1 mm to 10 mm, more preferably 1 mm to 2 mm, even more preferably 1.4 to 1.8 mm, although other thicknesses may be appropriate for certain embodiments of the present teachings. The thickness h 2  of the cover  40  is preferably less than or equal to the thickness h 1  of the associated insulating strip body  20 , although other thicknesses may be utilized, as desired. 
     The embodiment shown in  FIGS. 5 and 6  is well-suited for smaller values of the width a of the insulating strip body  20 , e.g., in the range of 8 to 20 mm, more preferably, 14 mm. In such embodiments, the thickness h 1  preferably is, for example, in the range of 1-3 mm, more preferably about 1.4 mm. 
     The embodiment according to  FIG. 7  is well-suited for values of the width a of the insulating strip body  20 , e.g., in the range of 20 to 40 mm, more preferably, 32 mm. In such embodiments, the preferred thickness h 1  is in the range of 1.5 to 1.8 mm. PA66 is the preferred material for the indicated widths and material thicknesses. 
     In one aspect of the present teachings, the insulating strip body  20  may consist only of synthetic material. That is, it may be formed without a metal insert. However, a metal insert also may be included in the insulating strip body  20 , if desired. 
       FIG. 8   a  shows another embodiment of the present teachings, which is designed with an eye towards improved shear strength and is illustrated in a plan view perpendicular to the longitudinal direction. The insulating strip  10  may have a width a in the x-direction in the range of about 10 mm to about 100 mm. A plurality of openings  24  preferably penetrate through the insulating strip body  20  in the height-direction (thickness-direction) y. In  FIG. 8   a , the openings  24  have a substantially triangular shape in the plan view and the corners of the triangles are rounded so as to have a radius R. The triangles also have a height c in the transverse direction x. 
     The triangles may be arranged in an alternating manner, such that, in the plan view in  FIG. 8   a , a lateral side of one triangle is alternately arranged in parallel next to the left side, then to the right side, then again to the left side, etc. Consequently, the vertices of the triangles are also arranged in an alternating manner. Rungs  23  are located between the triangles and have a width b perpendicular to the sides of the bordering triangles. The triangles are separated from the respective outer longitudinal edges  21 ,  22  in the transverse direction x by a distance or length e. Thus, it follows that a=c+2e. 
     The insulating strip  10  has a constant height (thickness) h in the height-direction y over its entire width, except for the crimping heads  25 , which may be thicker. Preferred values are provided as follows. For insulating strips  10  having a width a less than 22 mm, c preferably falls within the range of 7 to 10, more preferably about 8 mm. In such embodiments, the radius R is preferably less than 2 nm, more preferably less than 1 mm, and even more preferably about 0.5 mm. Such a radius serves to avoid a concentration of stress or the formation of a type of bending joint. The width b of the rungs  23  is preferably 1 to 3 mm, more preferably 2 mm. 
     For insulating strips  10  having a width a greater than or equal to 22 mm, c preferably falls within the range of 8 to 18 nm, more preferably about 12 mm. The height h in the height-direction y is preferably 1.2 to 2.4 mm, more preferably about 1.8 mm. The strip  10  is preferably formed of PA66 GF25. 
       FIG. 8   c  shows a modification of the sixth embodiment in a cross-sectional view, wherein the progression of the strip between the two crimping heads  25  is not linear, as in  FIG. 8   b , but rather is crooked or bent in the x-direction. 
       FIG. 8   d  shows a seventh embodiment that differs from the sixth embodiment in that the openings  24  are not substantially triangular, but rather are substantially rectangular. The cross-section of the insulating strip body  20  perpendicular to the longitudinal direction can be the same as depicted as in  FIG. 8   b  or  8   c . The dimensions for a, b, c, e or R indicated above for the sixth embodiment also apply to the seventh embodiment. The dimension d, i.e., the extension or length of the openings  24  in the longitudinal direction z preferably falls within the range of 3 to 8 mm, more preferably about 5 mm. This dimension d also applies to the preferred maximal extension or length of the triangular openings  24  of the sixth embodiment, although the dimension d is not shown in  FIG. 8   a.    
       FIG. 8   e  shows an eighth embodiment that differs from the sixth and seventh embodiments, in that the openings are circular with a diameter C.  FIG. 8   f  shows a ninth embodiment that differs from the sixth and seventh embodiments, in that the openings are hexagonal. The remaining specifications for the sixth and seventh embodiments also apply to the eighth and ninth embodiments, as far as they are applicable. 
       FIG. 9  shows an insulating strip having a so-called “package-design”,  FIG. 9   a  shows the plan view perpendicular to the longitudinal direction and  FIG. 9   b  show a cross-sectional view relative to the longitudinal direction. This package-design is intended to be assembled in a composite profile, such as is shown in an exemplary manner in cross-section in  FIG. 7   c.    
     In this embodiment, four crimping heads  25  are crimped in the four corresponding retainers or grooves of the profiled components (e.g., metal frames), as is readily apparent from a comparison with  FIG. 7 . To achieve this connection to the profiled components, the upper insulating strip portion  20   a  shown in  FIG. 9   b  is crimped upwards (as compared with  FIG. 7   c ) and the lower insulating strip portion  20   b  in  FIG. 9   b  is crimped downwards (as compared with  FIG. 7   c ). The two insulating strip portions  20   a ,  20   b  are connected by a clipped-on (snap-fit) connecting piece  20   c . This embodiment provides, on the one hand, a shielding against convection and radiation between the inner and outer sides of the composite profile and, on the other hand, a plurality of hollow chambers  20   d  is formed. The hollow chambers  20   d  are divided in the height-direction y by a diagonal strut  20   e  of the connecting piece  20   c.    
     As can be seen in  FIG. 9   a , the openings  24  have a width f in the transverse direction x and a longitudinal extension or length d in the longitudinal direction Z and can be formed in one or more insulating strip components  20   a ,  20   b  and/or in the connecting piece  20   c . Each insulating-strip component  20   a  and  20   b  shown in  FIG. 9   b  also has outwardly-directed protrusions  20   f  that can form retainers, e.g., for rubber sealing elements and/or mounting components. However, the protrusions  20   f  are optional components of the illustrated embodiment. The number of openings  24  and the width and length of the openings  24  are not limited to the arrangement shown in  FIG. 9   a  and may be freely selected by the designer. 
       FIG. 10  shows another embodiment of the present teachings, which will be referred to herein as a “hollow-chamber profile”. In such a hollow-chamber profile, hollow chambers are located in the transverse direction x between the crimping protrusions  25 . For comparison purposes, the cross-section of a conventional hollow-chamber profile is shown in  FIG. 10   d . As is readily apparent from a comparison with the cross-section of the eleventh embodiment in  FIG. 10   b , the difference is, in essence, that a wall is removed from the central hollow-chamber between the rungs  23 , thereby forming an opening  24 . The openings  24  have a width g in the transverse direction x and a longitudinal extension or length d in the longitudinal direction z. 
     In particular for hollow-chamber profiles having a width a greater than or equal to 25 mm, g preferably falls within the range of about 8 to 18 mm, more preferably about 12 mm. With the modifications shown in  FIG. 10   c , an opening  24  is formed only on one side of the hollow-chambers. In accordance with the modifications shown in  FIGS. 10   e  and  10   f , the part of the hollow chamber profile, in which one or more openings  24  are formed, is filled with foam that serves as a filling material. This foam preferably is pure foam having a lower thermal conductance coefficient than the material forming the insulating strip body  20 . The other specifications noted above for, e.g., values a, b, d and R may be likewise utilized for this embodiment. The thicknesses h 5  and h 6  may be the same or different. 
       FIGS. 11   a  to  11   f  show modifications of the sixth to ninth embodiments in views with the same numbering a to f as  FIG. 8 , wherein a projection  28  is formed on each insulating strip body  20 . This projection  28  protrudes from the insulating strip body  20  substantially in the height direction y and may preferably serve to obstruct convection and radiation. The height of the protrusion  28  in the height-direction y is chosen to achieve this effect. In  FIG. 7   c , the installation of an insulating strip  10  having such a protrusion  28  is indicated by broken lines. An especially-effective obstruction of the convection and radiation is achieved when the above-described insulating strip  10  shown in  FIG. 7   c ) has one or more corresponding protrusions  28  that overlap with the lower protrusion  28  as viewed in the transverse direction x.  FIGS. 12   a - d  show modifications of insulating strips having two such protrusions  28 . 
     All embodiments shown in  FIGS. 8 to 12  are preferably provided either with an in situ extruded cover of the type shown in  FIGS. 5 and 6  or with clip-protrusions and/or clip retainers of the type shown in  FIG. 7 . In the alternative, it is also possible to provide sheets or films for covering the openings or to introduce a foam into hollow-chambers of the insulating strip body  20 , which foam preferably comprises a material that is less heat conductive than the material of the insulating strip bodies. 
     Suitable materials for the insulating-strip bodies  20  are rigid-PVC, PA, PET, PPT, PA/PPE, ASA, PA66, wherein PA66 GF25 is preferred. Suitable foams are preferably selected from thermosetting materials such as polyurethane, and more preferably the foam has a relatively low density, such as about 0.01 to 0.3 kg/l. 
     Previous applications of ladder-like profiles were aimed at achieving low shear strength (high longitudinal movability). In one other application, openings were provided only to reduce the heat conductance of a metal insert known to be extremely conductive. 
     With the preferred embodiments having one or more at least partly in situ extruded covers clipped onto one side of the insulating strip body, more preferably entirely clipped-on covers, as well as embodiments having adhered or laminated sheets for covering the openings, it has been surprisingly found, in particular for the entirely or partly clipped-on covers, that these covers only marginally influence the k-values, i.e. the heat-isolation characteristics of the insulating strip, as compared to non-covered versions. 
     Tests with a solid strip having a cross-section of the type shown in  FIG. 5   b , i.e. with a strip having no openings, which strip has a width of 25 mm and a height h of 1.8 mm and is made from PA26GF25, have resulted in a k-value (W/m 2 K) of 2.4. An insulating strip of the type shown in  FIG. 8   d , in which c is 8 mm and d is 2 mm and without a cover, resulted in a k-value of 2.15 W/m 2 K. A corresponding strip with a clipped-on cover according to  FIG. 7  had a k-value of 2.25 W/m 2 K. These measurements were performed in a so-called “hot-box”, wherein a system having 25 mm wide, flat insulating strips was used as the initial system; the strips were not exchanged during the course of the test. Therefore, the improvements of the k-values are expected to be even better in reality. 
     Although the cause of this effect has not yet been conclusively ascertained, it is presumed that it lies in the form of the clip connections, which severely restrict or narrow the heat transmission path through the cover. 
     For the embodiments having hollow chambers shown in  FIGS. 9 and 10 , which have already been tested in systems with very good insulating properties, these properties can be further improved. The use of convection- and/or radiation-shielding protrusions  28  also increases the effect. 
     Each of the various features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved insulating strips, and composite structures incorporating such insulating strips, as well as methods for designing, manufacturing and using the same. Representative examples of the present invention, which examples utilize many of these additional features and teachings both separately and in combination, were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Therefore, combinations of features and steps disclosed in the detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the present teachings. 
     Moreover, the various features of the representative examples and the dependent claims may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings. In addition, it is expressly noted that all features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original disclosure, as well as for the purpose of restricting the claimed subject matter independent of the compositions of the features in the embodiments and/or the claims. It is also expressly noted that all value ranges or indications of groups of entities disclose every possible intermediate value or intermediate entity for the purpose of original disclosure, as well as for the purpose of restricting the claimed subject matter. 
     The contents of U.S. Pat. Nos. 5,313,761, 5,675,944, 6,038,825, 6,068,720 and 6,339,909 and US Patent Publication Nos. 2005-0100691 and 2005-0183351 provide additional useful teachings that may be combined with the present teachings to achieve additional embodiments of the present teachings, and these patent publications are hereby incorporated by reference as if fully set forth herein.