Abstract:
A hub cap for a vehicular wheel. The hub cap includes a body portion and a wheel coupling portion, both made from a non-metallic material. The wheel coupling portion has circumferentially-spaced lug nut engaging members that are axially alignable with lug nuts extending from the wheel. The lug nut engaging members form a substantially arcuate shape, and are resiliently biased so that upon placement of the hub cap onto a wheel, the lug nuts push the lug nut engaging members in a radial direction. Continued contact between the lug nuts and their corresponding engaging members promotes secure connection between the hub cap and wheel. In one embodiment, the body portion and wheel engaging portion is formed from two separate pieces that are subsequently joined, while in another, they are formed from a single unitary structure to define a one-piece construction.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates generally to a vehicular hub cap, and more particularly to attachment features formed in a hub cap to enhance attachment integrity under harsh environmental conditions.  
         [0002]     Decorative wheel covers form an important part of a vehicle&#39;s appeal, and can be used to cover portions or all of an outward-facing surface of a vehicular wheel. Such covers allow conventional fabricated steel wheels to emulate the aesthetically-pleasing attributes of polished, chrome-plated or cast aluminum wheels at a small fraction of the cost. Most wheels for such applications include a rim section, a spoke (or web) section and a central hub section, the latter of which allows for connection between the wheel and an axle. The hub section is one area of the wheel&#39;s outward-facing surface that can especially benefit from decorative covers, as otherwise unsightly lugs, lug nuts and axle spindles are left exposed. Wheel covers that overlie the hub section are often referred to as hub caps.  
         [0003]     Increasingly, hub caps are made from inexpensive, lightweight, non-metallic materials (for example, plastic) that are easily formable, impact-resistant, and (with the placement of an appropriate metallized coating on a surface thereof) capable of providing a desirable level of metallic finish and luster. In another form, hub caps could have the color molded-in, or coated with a secondary finish, such as paint or the aforementioned metallized finish. While the use of highly decorative hub caps is in its ascendancy, difficulties in reliably and inexpensively securing these hub caps to the underlying wheel or lug nuts used to secure the wheel to an axle jeopardize their long-term viability. Fasteners, such as resilient snap-fit extensions on the back (inward-facing) surface of the cover, can be employed to keep the cover affixed to the wheel to withstand the sort of rotational and vibration loading typically encountered in a vehicular environment. Often, these snap-fit fasteners are integrally formed (i.e., unitary, or one-piece) with the wheel cover. Other resilient fasteners, forming a friction-fit rather than a snap-fit, have also been used. In an alternative to snap-fit and friction-fit fasteners, high-strength adhesives have also been used. The use of such adhesives, while potentially beneficial for thermal protection of, and acoustic enhancement to, wheel covers, necessitates relatively detailed placement and assembly procedures to ensure weight minimization, adequate affixation and dynamic balancing, with concomitant increases in manufacturing costs. As such, the use of the aforementioned resiliently-biased snap-fit and friction-fit fasteners has enjoyed a prominent place in the wheel cover market.  
         [0004]     Nevertheless, the fasteners, which are typically in the form of cantilevered, tubular cups with segmented, finger-like extensions formed on the inner surface of the hub cap can soften, creep or otherwise suffer reduced grip on the lug nuts as a result of high temperature and rotational loads. These conditions result from wheel rotation and braking. For example, braking in loaded trucks can produce temperatures in the lugs and lug nuts of up to 400 degrees Fahrenheit, a temperature that would soften (if not outright destroy) many conventional plastic materials. Furthermore, differences in the rate of thermal expansion of the metallic wheel and the plastic hub cap can exacerbate an already loose or weakened fastener connection. In addition, individual fingers within the fasteners may be susceptible to breakage due to improper alignment, mounting and handling. Other approaches may employ multi-piece construction with metallic fasteners. While such a construction may have the advantage of better resistance to the buildup of heat, it does so with increases in weight and cost through the use of stamped metal parts that may require coating or related environmental protection to avoid the effects of rust or related corrosion. Moreover, schemes to attach the fasteners to the hub cap may be susceptible to heat or vibration-induced wear and subsequent separation, as friction-fit connections can work their way loose over extended periods of operation.  
         [0005]     What is needed is a way to secure a hub cap to a wheel inexpensively and reliably under all of the conditions normally encountered in a vehicular environment. Also desired is a hub cap that can satisfy the above needs without using metal-based structural components.  
       SUMMARY OF THE INVENTION  
       [0006]     These needs are met by the present invention, where a hub cap can be affixed to a wheel to ensure a durable, robust connection between the two. In a first aspect of the invention, the hub cap includes a non-metallic body portion defining an inner (inward-facing) surface and an outer (viewable) surface, and a non-metallic wheel coupling portion extending from the inner surface of the body portion. In the present context, the term “non-metallic” and its variants is used to define the material makeup of the main structural attributes of the body portion and the wheel coupling portion. The incidental use of metal for chiefly aesthetic reasons, such as the placement of a metallized coating to give a chrome or related glossy finish on the surface of the body portion, is not inconsistent with such coated portion being construed as non-metallic. The wheel coupling portion comprises a plurality of resiliently biased, lug nut engaging members disposed about the periphery of the body portion and axially alignable with lug nuts disposed on a wheel.  
         [0007]     The resiliently biased configuration of the lug nut engaging members may be due to, for example, a cantilevered construction of the members relative to the body. By engaging the lug nut, the lug nut engaging members radially deflect to an extent necessary to cooperate with one another to keep the hub cap attached to the wheel. Each of the lug nut engaging members includes a substantially arcuate base configured to engage axially at least one surface of the lug nut, and a substantially arcuate crown axially aligned with and disposed axially inward relative to the substantially arcuate horizontal base. Inherent in an arcuate structure is the partial, bow-like contact area with the device it surrounds. By having only a portion of the circumference of a lug nut engaged rather than substantially full circular contact area, the present lug nut engaging members provide more assembly tolerance, as well as reduced susceptibility to member breakage. In the present context, the term “substantially” is utilized to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. As such, it refers to an arrangement of elements or features that, while in theory would be expected to exhibit exact correspondence or behavior, may in practice embody something slightly less than exact. The term also represents the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.  
         [0008]     Optionally, the lug nut engaging members include numerous anti-rotation standoffs disposed about the base. These standoffs may, for example, include generally planar surfaces that can be placed against the faceted outward surfaces of a standard hexagonal-shaped lug nut to inhibit nut rotation. The lug nut engaging members may include an axial stiffening rib to enhance flexural resistance. Such flexure (i.e., radial deflection) of the members may be caused by, among other things, contact with the lug nuts, high rotational (centrifugal) loading or the like. The crown may define a castellated structure, which may include beveling to promote ease of insertion with a corresponding lug nut. In a particular form, the base and crown define a radially outward portion of each of the lug nut engaging members. A retaining wire may be disposed on this radially outward-facing surface of the lug nut engaging members. This wire can be made from a variety of structural, relatively temperature-resistant materials, including ceramics (including fiber-reinforced ceramic composites), high temperature plastics or metal. Furthermore, a series of brackets may be formed in the inner surface of the hub cap body portion to allow a secure fit of the wire.  
         [0009]     In one variant of the hub cap design, the lug nut engaging members can be integrally formed with the body portion to define a one-piece hub cap design. In another variant, the lug nut engaging members are integrally formed with one another on a common ring, which in turn can be removably attachable to the body portion, thereby resulting in a two-piece hub cap design. In this latter configuration, a boss can be formed on the inner surface of the hub cap body portion. The boss can define an aperture therein to allow passage of projecting connectors (also referred to as projections) situated on the ring. In one form, the projections are resiliently-biased snap-fit detents that are integrally formed in the ring. At least one of the ring and the hub cap can be made from a plastic, ceramic or continuous or discontinuous reinforced composite based on plastic or ceramic. In situations where excessive heat soaking may be experienced, the ring can be molded from a separate, higher-temperature plastic, ceramic or composite material, such as a glass-reinforced nylon. To enhance the outward appearance of the hub cap, a metallic (for example, chrome or chrome-like) coating may be used in the body portion. In another form, colors may be painted onto or molded in the body portion to enhance its appearance.  
         [0010]     In the one-piece variant of the hub cap, the lug nut engaging members form a substantially cantilevered attachment to the body portion. In this way, the base forms a proximal end (i.e., closest to the point of connection between the body portion and the lug nut engaging members), while the crown defines a distal end. The inherent flexibility in a cantilever structure allows the distal portion adjacent the crown to move radially relative to the proximal end and the body portion. As with the two-piece variant discussed above, plastic, ceramic or composite materials may be used. Also as with the two-piece variant discussed above, the outward appearance of the hub cap can be augmented by the addition of a metallic coating, painted-on coating or through molded-in color.  
         [0011]     According to another aspect of the invention, a hub cap, comprising a body portion and a wheel coupling portion, is disclosed. The body portion defines an inner surface and an outer surface. The inner surface comprises a boss with an aperture that allows the wheel coupling portion to be removably attachable. The wheel coupling portion includes a ring, numerous circumferentially spaced and resiliently biased lug nut engaging members disposed on the ring, and a plurality of projections disposed on the ring. The projections are oriented to engage the boss aperture to facilitate connection between the wheel coupling portion and the body portion. The lug nut engaging members extend axially inward and are alignable with corresponding lug nuts disposed on a wheel. Each of these members includes a proximal end, defining a base configured to engage axially a corresponding one of the lug nuts, and a distal end, defining a substantially arcuate crown axially aligned with, and disposed axially inward relative to, the base. In this way, radial deflections imparted to each of the crowns by the lug nuts promote a secure connection between the hub cap and the wheel.  
         [0012]     Optionally, the projections comprise snap-fit detents. The snap-fit detents preferably define an angled distal portion. Likewise, the boss aperture defines a beveled surface to facilitate the insertion of the angled distal portion of snap-fit detents. As stated in conjunction with an earlier aspect, the lug nut engaging members and the projections can be integrally formed with the ring, where the ring, lug nut engaging members and projections can be made from a temperature-resistant, non-metallic material.  
         [0013]     According to another aspect of the invention, a wheel assembly includes a wheel and a hub cap configured to cover at least a portion of the wheel. The hub cap includes a body portion defining an inner surface and an outer surface, and a wheel coupling portion extending from the inner surface of the body portion. The wheel coupling portion comprises a plurality of circumferentially spaced and resiliently biased lug nut engaging members that are axially alignable with corresponding lug nuts. The lug nut engaging members are configured to secure the wheel to a vehicle. Each of the lug nut engaging members includes a substantially arcuate base configured to engage axially a corresponding one of the lug nuts, and a substantially arcuate crown, axially aligned with and disposed axially inward relative to the base. As before, radial deflections imparted to each of the lug nut engaging members cause them to cooperate with the lug nuts, thereby keeping the hub cap attached to the wheel.  
         [0014]     Optionally, the lug nut engaging members can be either integrally formed with the body portion to define a one-piece structure, or can be integrally formed with one another on a common ring. In this latter (two-piece) configuration, the ring includes numerous snap-fit detents that make the ring removably attachable to the body portion by engaging the snap-fit detents through an aperture defined in a boss formed on the inner surface.  
         [0015]     According to still another aspect of the invention, a method of covering a vehicular wheel is disclosed, where the wheel includes an inner surface, an outer surface and a plurality of lug nuts protruding substantially outward from the outer surface. It will be appreciated that the wheel outer surface is that which is viewable by an observer standing away from the vehicle when the wheel is mounted onto the vehicle. The method includes providing a wheel and a hub cap and securing the hub cap to the wheel such that lug nuts used to secure the wheel to an axle or other part of a vehicle impart a radial deflection to corresponding lug nut engaging members, thereby causing them to keep the hub cap attached to the wheel. As before, the hub cap includes a body portion and a wheel coupling portion extending from an inner surface of the body portion. The wheel coupling portion includes numerous circumferentially spaced and resiliently biased lug nut engaging members. Each of the lug nut engaging members includes a base to engage axially one of the lug nuts, and a substantially arcuate crown axially aligned with and disposed axially inward relative to the base.  
         [0016]     Optionally, the method includes configuring the wheel coupling portion as a ring with extending lug nut engaging members, and creating a snap-fit connection between the ring and the body portion to facilitate removable attachment between the ring and body portion. At least one of the body portion and the ring may be made from the aforementioned ceramic, plastic or composite based on either or both. As previously discussed, the method may include reinforcing the lug nut engaging members with a retaining wire. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is an exploded front view of a wheel assembly showing its attachment to a vehicle according to a first aspect of the present invention;  
         [0018]      FIG. 2  is a rear cutaway view of a hub cap of the wheel assembly of  FIG. 1 , showing both hub cap body portion and wheel coupling portion in the form of a ring;  
         [0019]      FIG. 3  is a rear view of the hub cap of  FIG. 2  with the ring removed;  
         [0020]      FIG. 4  is a front view of the ring of  FIG. 2  with lug nut engaging members;  
         [0021]      FIG. 5  is a rear view of the ring of  FIG. 4 ;  
         [0022]      FIG. 6  is a cutaway view of the hub cap of  FIG. 2  secured to the lug nuts of a portion of an automotive wheel;  
         [0023]      FIG. 7  is a rear cutaway view of a hub cap according to a second aspect of the present invention;  
         [0024]      FIG. 8  is rear cutaway view of the hub cap of  FIG. 7 , with a retaining wire disposed around the outer periphery of a lug nut engaging member that is integrally formed with the hub cap;  
         [0025]      FIG. 9A  is a radially inward-looking view showing a variation on the ring of  FIGS. 4 and 5  with an alternate connection scheme between the ring&#39;s lug nut engaging member and a retaining wire;  
         [0026]      FIG. 9B  is a radially outward-looking view of the lug nut engaging member and the retaining wire of  FIG. 9A ;  
         [0027]      FIG. 10  shows the lug nut engaging member and the retaining wire of  FIG. 9A  over a larger portion of the ring, illustrating alternating wire attachment locations; and  
         [0028]      FIG. 11  shows a retaining wire retention scheme that differs from of  FIGS. 9A, 9B  and  10 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]      FIG. 1  is an outward-facing exploded view of a wheel assembly  100  with wheel  200  and hub cap  300 , both configured to be mounted to a hub  1  and axle  10  of vehicle  15 . The wheel  200  includes a rim (or flange) section  210 , central hub section  220  with lug-receiving holes  230  and central bore  240 , and web (or spoke) section  250 . Hub  1  includes holes therein (not shown) to allow threaded placement of lugs  20  which in turn allow threaded attachment of lug nuts  30 . The corresponding holes  230  formed in wheel  200  allow placement of lugs  20  through the aligned holes, while accompanying lug nuts  30  secure the wheel  200  to the hub  1  through the lugs  20 . A tire  50  is also mounted onto the rim section  210  of wheel  200 .  
         [0030]     In a preferred (although not necessary) embodiment, the hub cap  300  is made from a non-metallic material, such as plastic or related resin, examples of which may include acrylonitrile-butadiene-styrene (ABS), polycarbonate or a combination thereof. The material may further include continuous or discontinuous fiber reinforcements, such as glass, polymers, ceramics or the like. The hub cap  300  includes an outer surface  310  and inner surface  320 . A body portion of hub cap  300  defines the general external configuration, while a wheel coupling portion, which cooperates with inner surface  320  and is discussed in more detail below, promotes secure connection between the hub cap  300 , and the wheel  200  or the lug nuts  30 , or both. In the present context, the outer surface of the hub cap  300  is that which is visible to an observer when the wheel  200  is mounted to an automobile or related vehicle and is covered by the hub cap  300 . Accordingly, the outer surface  310  of hub cap  300  is configured to provide an aesthetically-pleasing cover for at least a portion of central hub section  220 , and may (among other things) be metallized with an appropriate coating to define a chrome-like or related appearance. The inner surface  320  may or may not include a metallized coating, depending on the need or on the method of manufacture. For example, a metallized coating may or may not be placed on the inner surface  320 , depending on whether the hub cap  300  is masked prior to coating deposition. In another variation on aesthetic enhancement, the hub cap may include molded-in coloring or have its outer surface painted.  
         [0031]     Referring next to  FIGS. 2 through 5 , views of the inner surface  320  of a two-piece embodiment of the hub cap  300  are shown.  FIG. 6  depicts its attachment to the lug nuts  30  of wheel  200 .  FIG. 2  is a cutaway view that shows the cooperation of the inner surface  320  and a series of circumferentially-spaced lug nut engaging members  340  that are integrally formed at a proximal end base  340 A on a lug nut engaging ring  350 . The lug nut engaging members  340  each define an arcuate structure  341  that extends axially inward to a distal end crown  340 B to affix the hub cap  300  to wheel  200  by engaging the lug nuts  30 . By its arcuate shape, each lug nut engaging member  340  exhibits greater flexural rigidity than a generally planar member, yet is not so rigid that the lug nut engaging member  340  may not be flexed when pressed upon by a lug nut  30 . As can be seen in the figures, the crown  340 B of each lug nut engaging member  340  may define a castellated structure  341 , and may further form a radially-projecting protrusion  342  that includes bevelling to facilitate engagement with a surface of lug nut  30 . The castellated structure  341  enhances the flexibility of the member  340 . The base  340 A of each of the lug nut engaging members  340  surrounds a generally circular aperture  351  formed in the ring  350  through which at least a portion of one or both of the lug  20  and lug nut  30  are configured to pass. Resiliently-biased ring detents  353  are integrally formed on the ring  350  and spaced between adjacent lug nut engaging members  340 . They extend axially outward from the opposite side of the ring  350  from which the lug nut engaging members  340  are disposed.  
         [0032]      FIG. 3  highlights the rear (inward-facing) cutaway view of the inner surface  320 , including a series of circumferentially-spaced bosses  323  defining rectangular mounting apertures  325 . The axially inward-facing surface of the mounting apertures  325  are axially coplanar with one another, and include bevels or chamfers  329  to promote the insertion and cooperation of resiliently-biased ring detents  353 . By integrally forming the bosses  323  into the inner surface  320  of the hub cap  300 , complexity of the molds required to form the hub cap  300  is reduced, as all features can be formed in the line of the mold draw as the mold opens. Opposed slots  360  can be formed in the body portion of hub cap  300  to facilitate the insertion of a tool (for example, a screwdriver) with which to pry the hub cap  300  off a wheel  200 . The lowermost edge  370  is generally planar so that when placed in contact with an adjoining surface of wheel  200 , the hub cap  300  is properly oriented to avoid misalignment and concomitant hub cap wobble.  
         [0033]      FIGS. 4 and 5  show the ring  350  from axially opposing sides.  FIG. 4  shows the axially inward-facing side of ring  350 , from which the circumferentially-spaced lug nut engaging members  340  extend. As can be seen, the lug nut engaging members  340  are integrally formed into ring  350 . Apertures  351  are formed in the ring  350 , and define a generally circular (or at least semicircular) shape. Semicircular horizontal ribs  352  extend radially inward from ring  350  and cooperate with base  340 A of lug nut engaging member  340  to define a securing area for lug nut  30  and allow passage of lug  20 . In addition, horizontal ribs  352  may form a tiered structure to permit the innermost surface of lug nut  30  to rest on a shelf  352 A (shown with greater clarity in  FIG. 11 ) while having portions of the lateral surface of lug nut  30  fit within the circumference partially defined by horizontal rib  352 . Snap-fit detents (also referred to as tabs)  353  possess a resilient bias that is overcome when ring  350  is pushed into aperture  325  of boss  323  until the detents  353  snap into place. As shown in  FIG. 5 , the detents  353  include a proximal end  353 A that is adjacent the ring  350  and a distal end  353 B with pawls  353 C or related accentuated heads that are configured to secure the detent  353  to the portion of the boss  323  that surrounds aperture  325 . As stated earlier, the ring  350  can be made from a temperature-resistant material, such as a high-temperature plastic, ceramic or composite based on plastic or ceramic. One suitable material is a glass-reinforced nylon composite. Anti-rotation standoffs  355  are formed on either the ring  350  or the lug nut engaging members  340  to engage one or more of the faceted surfaces  31  of the lug nut  30  to inhibit its rotation.  
         [0034]      FIG. 6  shows a cutaway view of the engagement of the hub cap  300  to the wheel  200  through the use of the ring  350 , lug engaging members  340 , lugs  20  and lug nuts  30 . Ring  350  is secured to the hub cap  300  by the snap-fit detents  353  that extend through aperture  325  formed in boss  323  that is integrally formed into inner surface  320  of the body portion of hub cap  300 . A bevelled connector  40  can be used to provide a secure mounting location for the distal end  340 B and corresponding radially-projecting protrusion  342  of lug nut engaging member  340 . The bevelled connector  40  can be either integrally formed with lug nut  30 , or can form a separate piece.  
         [0035]     Referring next to  FIG. 7 , the inner surface  420  of a one-piece embodiment of the hub cap  400  is shown in cutaway view. Unlike the embodiment of  FIGS. 2 through 6 , this embodiment can be formed from a single molded part, as lug nut engaging members  440  are integrally formed into the inner surface  420 . As with the previous embodiment lug nut engaging members  340 , the lug nut engaging members  440  of  FIG. 7  define an arcuate structure  441  that extends axially inward from a proximal base  440 A to a distal end crown  440 B. As discussed above, in situations requiring prolonged high-temperature durability, appropriate parts, may be made from materials (such as those previously discussed) specifically configured for elevated temperature environments. In the present embodiment, if such elevated temperature capability were required, the entire hub cap  400  could be formed from such a material.  
         [0036]     Referring next to  FIG. 8 , the use of a retaining wire  500  to provide additional radial support to lug nut engaging member  440  is shown. As previously mentioned, retaining wire  500  can be made of ceramics or high-temperature plastics (including fiber-reinforced composites thereof), metal or other high strength, heat-resistant material. Projections  480  built into the inner surface  420  of hub cap  400  can be arranged to ensure a frictional fit of retaining wire  500  during wheel operation. It will be appreciated by those skilled in the art that the retaining wire  500  is compatible with either the presently-shown one-piece hub cap  400  or the two-piece hub cap  300 .  FIG. 8  also illustrates a different configuration for the anti-rotation standoffs  455  that includes longer flat sides that can contact a larger portion of one of the faceted surfaces  31  of lug nut  30 . As shown, standoff  455  can be integrally formed with the inner surface  420 . It will be further appreciated by those skilled in the art that either of the anti-rotation standoffs  355  or  455  are equally useable with either the one-piece or two-piece hub cap configurations. Lug nut engaging member  440  may otherwise be similar to that shown previously, including having an arcuate crown  441 . As with the two-piece configuration shown earlier, the present one-piece configuration has a generally planar lowermost edge  470  to properly seat hub cap  400  with an adjoining surface of wheel  200  to avoid misalignment and related wobble. In addition, slot  460  formed in the side of hub cap  400  is included facilitate separation of the hub cap  400  from the wheel  200 .  
         [0037]     Referring next to  FIGS. 9A through 11 , cooperation of the retaining wire  500  with the lug nut engaging member  340  of ring  350  is shown. Each lug nut engaging member  340  may also include a stiffening rib  347  disposed longitudinally on the surface away from the side that engages the lug nut  30 . In addition to providing enhanced flexural rigidity, it can include a ledge  347 A to act as a contact point for retaining wire  500  to promote the aforementioned frictional fit. To that end, additional devices can be used, such as flexible retaining wire retention device  380  (shown with particularity in  FIGS. 9A and 9B ) to cooperate with ledge  347 A or a projection similar to that depicted in  FIG. 8 . Referring with particularity to  FIG. 11 , an alternative attachment scheme for retaining wire  500  is shown. In it, stiffening rib  349  is affixed to or formed on the radially outward-facing surface of lug nut engaging member  340 . To keep the ability of the lug nut engaging member  340  to flex, stiffening rib  349  could be affixed directly to ring  350  without contacting lug nut engaging member  340 . The top of stiffening rib  349  serves as a lower mounting surface of the retaining wire  500 , while a projection  390  forms an upper mounting surface to keep the retaining wire  500  in place. In one form, a tight friction fit may clamp the retaining wire  500  in place. Other equivalents to the ledge  347 A and the upper surface of the stiffening rib  349  could also be employed to provide additional axial support to retaining wire  500 . For example, a projection (not shown) could be integrally formed around the periphery of ring  350  and extend axially a distance sufficient to contact an opposite side of retaining wire  500  from that of projection  390 .  
         [0038]     Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.