Abstract:
A filter, for use in removing residual fuel vapors from within an engine&#39;s intake system, includes a filter element having a plurality of fibers, for placement in communication with an intake air flow passage. Each of the fibers has an internal cavity formed therein, and a longitudinally extending slot formed therein extending from the internal cavity to the outer fiber surface. The filter also includes a hydrocarbon-absorbing material disposed within the internal cavities of the fibers. The hydrocarbon-absorbing material may be a solid material such as, e.g., carbon, or may be a liquid such as a relatively non-volatile organic solvent. Alternatively, the material may be a combined solid and liquid. In one embodiment, each of the elongated fibers includes a central stem and a plurality of lobes extending outwardly from the central stem, with a longitudinally extending slot defined between adjacent lobes. Specific useful filter configurations are detailed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the invention 
     The present invention relates to a filter for reducing evaporative fuel emissions from an internal combustion engine. More particularly, the present invention relates to a filter for placement on an engine, downstream of a throttle plate, to adsorb evaporative emissions after the engine has been turned off. 
     2. Description of the Background Art 
     The great majority of internal combustion engines in use today are fuel-injected engines. When a fuel-injected engine is switched off after use, a small amount of residual fuel volatilizes and escapes from the injector tips. While a vehicle is sitting over time after use, this evaporated fuel may pass outwardly through the intake manifold, the intake air ducts and air filter, and may escape into the atmosphere, thus contributing to air pollution. It would be desirable to minimize this type of inadvertent evaporative emissions leakage. 
     Many different types of filters are known for use in filtering evaporative fuel emissions in specific applications. Examples of some of the known filter types are described in U.S. Pat. Nos. 4,133,762, 5,429,099, 5,453,118, and 5,912,368. 
     The assignee of the present invention has developed a new type of ‘wicking’ fiber material that has been used for some filter applications. This material includes hollow spaces within the individual fibers, and this hollow space may be used to house a reactive or adsorbent material. Some issued patents relating to this wicking fiber, and to filters containing this type of fiber include U.S. Pat. Nos. 5,057,368, 5,704,966, 5,713,971, 5,744,236, 5,759,394, 5,891,221, 5,902,384, 5,951,744, 6,004,381, 6,048,614, 6,117,802, and 6,127,036. Other patents using this fiber technology are pending. 
     Although the known devices have utility for their intended purposes, a need still exists in the art for an improved evaporative emissions filter, adapted to adsorb fuel vapors within an intake system of an internal combustion engine, subsequent to the engine being turned off. Preferably, such a filter would be capable of regeneration, so as to be repeatably usable over many cycles of engine operation. 
     SUMMARY OF THE INVENTION 
     The present invention provides a filter for use in removing residual fuel vapors from within an engine&#39;s intake system, downstream of a throttle body, after the engine has been turned off. 
     A filter in accordance with the present invention, generally, includes: 
     a filter element for placement within an intake air flow passage, the filter element comprising a plurality of fibers; 
     each of the fibers having an outer surface; 
     each of the fibers further having a longitudinally extending internal cavity formed therein, and having a longitudinally extending slot formed therein extending from the internal cavity to the outer fiber surface; and 
     wherein the filter further comprises a hydrocarbon-adsorbing material disposed within the internal cavities of the fibers. 
     The hydrocarbon-adsorbing material may be a solid material such as, e.g., carbon, or may be a liquid such as a relatively non-volatile organic solvent. Suitable organic solvents, which may be used in the fiber cavities, include mineral oils and paraffin oils. 
     In one embodiment of the invention, each of the elongated fibers includes a central stem and a plurality of lobes extending outwardly from the central stem, with each lobe having a longitudinally extending internal cavity on each side thereof, whereby a longitudinally extending slot is defined between adjacent lobes. 
     It is preferred that the filter be constructed and arranged to minimize pressure drop therepast, limiting the pressure drop to less than 5 inches of mercury at a flow rate of 5,000 cubic feet per minute (CFM) of air flow therepast. 
     Accordingly, it is an object of the present invention to provide a filter element for placement in an intake flow passage of an engine, the filter element being adapted to adsorb fuel vapors from ambient air in the immediate surrounding area. 
     It is a further object of the present invention to provide a method and apparatus for removing residual fuel vapors from an engine&#39;s intake system, downstream of the throttle body, after the engine has been turned off. 
     It is yet a further object of the invention to provide a filter for adsorbing fuel vapors out of ambient air, in which the filter minimizes pressure drop therepast, so as not to interfere with the free flow of air to the engine. 
     For a more complete understanding of the present invention, the reader is referred to the following detailed description section, which should be read in conjunction with the accompanying drawings. Throughout the following detailed description and in the drawings, like numbers refer to like parts. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a filter element according to a first embodiment of the invention, and also showing a throttle body, in phantom, surrounding the filter element; 
     FIG. 2 is a front plan view of the filter element of FIG. 1, showing a nonwoven fiber mat, and also showing a solid frame surrounding the nonwoven fiber mat; 
     FIG. 3 is an enlarged perspective detail view of the nonwoven fiber mat of FIG. 2, formed of wicking fibers according to the present invention; 
     FIG. 4 is a further enlarged perspective detail view of the nonwoven fiber mat of FIGS. 2-3, showing a solid component entrained in cavities of the fibers; 
     FIG. 5 is an enlarged perspective view of a three-lobed wicking fiber, which is usable in the practice of the present invention; 
     FIG. 6 is an enlarged perspective view of an alternative wicking fiber which is usable in the practice of the present invention, having a C-shaped cross-section with a single cavity formed therein; 
     FIG. 7 is an enlarged perspective detail view of the nonwoven fiber mat of FIG. 3, showing a liquid component entrained in cavities of the fibers; 
     FIG. 8 is a perspective view of a filter element according to a second embodiment of the present invention, in which the filter on the throttle plate is hinged to become horizontal during engine operation; 
     FIG. 9 is a perspective view of a filter element according to a third embodiment of the present invention, in which the filter is on a spring loaded throttle plate, hinged at the middle to fold in half during engine operation; 
     FIG. 10 is a perspective view of a filter element according to a fourth embodiment of the present invention, in which the filter is sectioned into horizontal louvers that are hinged on the sides thereof to allow pivotal movement; 
     FIG. 10A is an end plan view of one of the horizontal louvers of the filter of FIG. 10; 
     FIG. 11 is a front plan view of the filter of FIG. 10; 
     FIG. 12 is a perspective view of a filter element according to a fifth embodiment of the present invention, in which the filter includes two perforated screens with fiber strands extending therebetween; 
     FIG. 13 is a perspective view of a filter element according to a sixth embodiment of the present invention, in which the filter is hinged to open during engine operation and close when the engine is off, 
     FIG. 14 is a perspective view of a filter element according to a seventh embodiment of the present invention, in which the filter includes multiple fiber strands, attached at their upper ends to a support, and hanging freely at the lower ends; 
     FIG. 15 is a perspective view of a filter element according to an eighth embodiment of the present invention, in which the filter is a nonwoven fiber mat that is rolled into a spiral; 
     FIG. 16 is a perspective view of a filter element according to a ninth embodiment of the present invention, in which the filter includes a perforated support screen with multiple fiber strands attached to one side thereof and extending therefrom; 
     FIG. 17 is a perspective view of a filter element according to a tenth embodiment of the present invention, in which the filter includes a circular fiber mat which is divided into multiple wedge-shaped pieces to allow air flow therepast; 
     FIG. 18 is a perspective view of a filter element according to an eleventh embodiment of the present invention, in which the filter includes a conical support screen having multiple fibers attached thereto; 
     FIG. 19 is a perspective view of a filter element according to a twelfth embodiment of the present invention, in which the filter includes a liquid-filled reservoir, and multiple fibers in a substantially parallel array with one end of each of the fibers disposed in the liquid reservoir; and 
     FIG. 20 is a perspective view of a filter element according to a thirteenth embodiment of the present invention, in which the filter includes a fiber web having an upper end attached to a support, and a lower end which is freely movable. 
     FIG. 21 is a perspective view of a filter element according to a fourteenth embodiment of the present invention, in which the filter has an arcuate shape and is attached to a side wall of a neck portion of an intake manifold downstream of the throttle plate. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIRST EMBODIMENT 
     Referring now to FIGS. 1-7, a filter in accordance with a first embodiment of the invention is shown generally at  10 . The filter  10  is provided for placement in an intake airflow passage  15 , associated with an internal combustion engine (not shown). The airflow passage  15  does not form a part, per se, of the present invention. The filter  10  may be placed extending across a flow passage such as, for example, a portion of an intake manifold or a throttle body. 
     The filter  10  includes a filter element  11 , which comprises a porous non-woven fiber web  12  made up of a plurality of individual fibers  20  (FIG.  3 ). In the filter element  1   1 , the fiber web  12  is preferred to be made in a loose weave with relatively large air pockets between the fibers, in order to minimize pressure drop thereacross. 
     The pressure drop across the filter  10  is less than 5 inches of mercury at 5,000 cubic feet per minute of flow. Preferably, the pressure drop is less than 3 inches of mercury at 5,000 cubic feet per minute of flow. 
     Optionally, if desired, the filter  10  may include a reinforcing frame member  14 , such as the peripheral band  16  shown in FIG. 2, attached to and surrounding the fiber web  12 , in order to provide support thereto, and to provide a solid member for engaging a side wall of the air flow passage  15 . Alternatively, the filter element  11  may consist primarily of a fiber web  12 , adapted to be attached to the inside surface of the structural element defining the air flow passage  15 . 
     The Wicking Fibers 
     As noted, the filter element  11  comprises a nonwoven fiber web  12 , which is retained in the air flow passage  15 . The fiber web  12  is formed from a multiplicity of intertwined wicking fibers  20 , as shown in FIGS. 3 through 6. 
     Each of the wicking fibers  20  incorporates a vapor-adsorbent substance therein, selected for its capacity to react with vaporized fuel which may be present in the air being filtered, so as to remove a significant amount of the fuel vapor and prevent escape thereof. The vapor-adsorbent substance may be solid, liquid, or a combination of them. 
     FIGS. 3-5 show the fibers  20  making up the web  12  in an increasing level of detail and magnification in each succeeding figure. FIG. 3 shows an enlarged detail view of a number of the intertwined fibers  20  making up the web  12 . FIG. 4 shows a further magnified detail view of the fibers  20 , and also shows a number of solid particles  18  as one example of a substance which may be disposed therein. FIG. 5 is a close-up detail perspective view of an end of one preferred fiber  20 , with the substance deleted from the drawing for purposes of illustration, and FIG. 6 shows an alternative configuration for a fiber  30  which is usable in the practice of the present invention. FIG. 7 is similar to FIG. 4, but shows that a liquid substance  118  may be present in place of the solid particles  18  shown in FIG.  4 . 
     A wicking fiber that is particularly suitable for practicing this invention is disclosed in U.S. Pat. No. 5,057,368, the disclosure of which is incorporated by reference. This patent discloses a fiber formed from thermoplastic polymers, wherein the fiber has a cross-section with a central core or stem  25 , and a plurality of substantially T-shaped lobes  26  (FIG.  5 ). The legs of the lobes  26  intersect at the core  25 , so that the angle between the legs of adjacent lobes is from about 80 degrees to 130 degrees. The thermoplastic polymer is typically a polyamide, a polyimide, a polyester, a polyolefin, a polysulfone, or a combination thereof. The wicking fiber as illustrated in FIG. 5 is formed as an extruded strand having three hollow longitudinally extending interior cavities  22 , each of which communicates with the outer strand surface  28  by way of longitudinally extending slots  24  defined between adjacent lobes  26 . 
     The wicking fibers  20  are relatively small, having a diameter in a range between 30 and 250 microns. The width of the longitudinal extending slots  24  is normally less than one half of the diameter of the fibers  20 . 
     Referring now to FIGS. 4 and 5, the fiber  20 , the width of the slots  24 , and the particles  18  to be entrapped within the interior cavities  22  are selected so that when the particles  18  are forced into the longitudinal cavities  22  they are retained therein. The small solid particles  18  become mechanically trapped within the longitudinal cavities  22  of the fibers  20 , and are retained therein. This approach can be extended to substantially any powder, or other finely divided solid material, which one would like to entrap within a fiber medium, and which would be effective in entrapping fuel vapors. 
     A particularly preferred solid material for trapping fuel vapors is a large pore wood-based carbon. Preferably, the substance used will have the capability of being regenerated, such as, for example, the ability to release loosely bound fuel molecules when the ambient temperature is increased, such as when an engine reaches operating temperature. This property will allow the filter  10  to have a prolonged effective useful life. 
     After the fine solid particles are entrapped, the wicking fiber  20  may additionally be impregnated with a liquid substance. Alternatively, the wicking fiber may be impregnated solely with a liquid substance  118 , as illustrated in FIG.  7 . Suitable organic solvents, which may be used in the fiber cavities, include mineral oils, paraffin oils, and similar non-volatile organic solvents. 
     The capillary forces within the individual cavities  22  are much greater than those external to the fiber  20 , such that a liquid substance is readily wicked up within the interior of the fiber  20  without appreciable wetting of the external surfaces  28  or filling the inter fiber voids. The fibers  20  strongly retain the liquid through capillary action, so that the nonwoven web  12  is not wet to the touch, and the liquid will not shake off. In a nonwoven web  12  of such wicking fibers  20 , the area between the individual strands remains relatively free of the fine particles  18 , and of any liquid or other substance with which the internal cavities  22  of each fiber  20  are filled. 
     The fibers  20  may be made of one or more type of wicking material strands such as polyamides, polyimides, polyesters, polysulfones, polyolefins, or other suitable polymeric material which may be formed into the desired configuration, and which is stable with respect to the substance stored therein and the fluid being filtered therethrough. The multiple cross-sectionally T-shaped segments may have their outer surface  28  curved, as shown, or straight. While the wicking fiber  20  is depicted as tri-lobed in FIG. 5, it will be understood that any other number of lobes are suitable, particularly two, four or five lobes. 
     In addition other internal wicking fibers may be used, such as the C-shaped fiber shown in FIG. 6, having a single longitudinal extending slot  34 , and a single longitudinally extending cavity  32 . Other cross-sectional shapes may also be suitable for retaining substances therein. The specific shape of the wicking fibers is not critical, so long as the fibers selected can hold the vapor-adsorbent substance  18  within its cavities  22 , such that it is not easily displaced. 
     Using the Filter 
     In using the filter  10 , it is placed into the air flow passage  15 , which is formed in a structural component associated with an intake system of an internal combustion engine, to remove fuel vapors therefrom. Once the filter  10  is in place in the air flow passage  15 , it is fixed in place in the air flow passage by any suitable means of attachment. 
     As noted, in the preferred application thereof, the filter  10  is placed across the air flow passage  15 , in a location downstream of the throttle plate, so that the filter will be exposed to fuel vapors in the intake system, after the throttle plate is closed. At such time as there is fuel vapor present in the ambient air surrounding the filter  10 , the adsorbent material  18 , within the fibers  20 , will adsorb a significant amount of the vapor, and will temporarily trap the vaporized fuel and prevent it from escaping out of the intake system of the engine and evaporating into the atmosphere. 
     Later, when the engine is re-started, and the filter  10  is heated due to an increase in engine operating temperature, the fuel vapor present on the adsorbent material  18  will be released, and will pass into the intake to be burned. This release of the bound fuel will regenerate the adsorbent material, and will prepare it to adsorb more fuel in the next shutdown cycle. 
     Examples of Possible Alternative Structures for the Filter Element 
     The filter  10  shown in FIGS. 1-2 is just one of many different physical configurations that the filter according to the invention may take. Several other examples of possible filter configurations are shown in other figures of the drawings, and will be discussed briefly below. All of these filters share the common characteristics that: 
     They incorporate wicking fibers  20  of the general type discussed previously herein, 
     The wicking fibers have a fuel vapor-adsorbing substance disposed in the cavities thereof; and 
     They are designed to minimize pressure drop across the filter, and to keep such pressure drop to a value below 5 inches of mercury at a flow rate of 5,000 cubic feet per minute (CFM) of airflow therepast. Preferably, the pressure drop across the filter is less than 3 inches of mercury at a flow rate of 5,000 CFM. 
     Many of these embodiments include frame members of various configurations, to provide structural support and reinforcement to the wicking fibers, and to hold a plurality of fibers together to form a filter element. 
     SECOND EMBODIMENT 
     Referring now to FIG. 8, another embodiment of a filter  210  is shown in accordance with a second embodiment of the invention. In the illustration, a throttle plate  202  is shown disposed within an intake air flow passage  215  of a throttle body  205 , which is shown in phantom for purposes of illustration. The throttle plate  202  is generally conventional, and does not form a part of the present invention. 
     A circular disc-shaped filter element  211 , in accordance with a second embodiment of the present invention, is affixed to the rear surface of the throttle plate  202 . The filter element  211  may be glued on, or otherwised attached to the throttle body in conventional fashion. 
     The filter element  211  includes a porous non-woven fiber web  212  made up of a plurality of individual fibers  20 . The fibers  20  making up the filter element  211  are the same as previously discussed in connection with the first embodiment. 
     The fibers  20  are impregnated with a fuel vapor-adsorbing compound, as discussed herein in connection with the filter  10  of FIGS. 1-7. 
     THIRD EMBODIMENT 
     Referring now to FIG. 9, another filter assembly  310  is shown, in accordance with a third embodiment of the invention. In the embodiment of FIG. 9, a pair of semi-circular opposed baffle plates  302 ,  304  are provided for placement in an intake air flow passage  315 , associated with an internal combustion engine (not shown). The filter assembly  310  may be placed in a flow passage  315  such as, for example, a portion of an intake manifold. 
     These baffle plates  302 ,  304  may be made foraminous or solid, according to the application. The baffle plates  302 ,  304  are each pivotally mounted in the air flow passage  315 , so as to be movable between a horizontal, open position when the engine is running, and a vertical, closed position when the engine is off. 
     The filter  310  also includes a pair of filter elements  306 ,  308 , made in the same semi-circular D-shape as the baffle plates, and attached to the back surface thereof by any appropriate method. Each of the filter elements includes a porous nonwoven fiber web  312  made up of a plurality of individual fibers  20 , and the fibers have a fuel vapor-adsorbing compound associated therewith. The fibers  20  making up the filter elements  306 ,  308  are the same as previously discussed in connection with the filter  10  according to the first embodiment. 
     FOURTH EMBODIMENT 
     Referring now to FIGS. 10-11, another filter assembly is shown at  410 , in accordance with a fourth embodiment of the invention. The filter  410  is provided for placement in an intake air flow passage  415  associated with an internal combustion engine (not shown). The filter  410  may be placed extending across a flow passage such as a portion of an intake manifold or a throttle body, preferably in a location downstream of the throttle plate. 
     The filter  410  includes an annular frame member  416  for interfering placement in the air flow passage  415 . The filter  410  also includes a plurality of aligned parallel slats or louvers  402 , which are each independently attached to the frame member  416 , and which are interconnected via appropriate linkages, so as to be concurrently pivotally rotatable, in a manner similar to horizontal window blinds. Appropriate conventional operating hardware is attached to each of the slats  402 , to open and close the slats in coordinated movement thereof. Each of the slats  402  includes a support bar  406 , which may be foraminous or solid. Each of the support bars  406  carries a proportionally and correspondingly sized filter section  408  attached thereto, which comprises a porous fiber web  412  made up of a plurality of individual fibers  20 . The fibers  20  making up the filter section  408  are the same as previously discussed in connection with the first embodiment. 
     The fibers  20  are impregnated with a fuel vapor-adsorbing compound, as discussed herein in connection with the filter  10  of FIGS. 1-7. 
     FIFTH EMBODIMENT 
     Referring now to FIG. 12, a filter assembly is shown at  510 , in accordance with a fifth embodiment of the invention. The filter  510  is provided for placement in an intake air flow passage  515  associated with an internal combustion engine (not shown). The filter  510  may be placed extending across a flow passage such as a portion of an intake manifold or a throttle body, preferably in a location downstream of the throttle plate. 
     The filter  510  includes a filter element  511  which has two spaced apart foraminous support screens  516 ,  518 , which are interconnected via a center section  503 , made up of a plurality of substantially parallel fiber strands  20  extending therebetween. The fibers  20  making up the center section  503  of the filter  510  are the same as previously discussed in connection with the first embodiment, except that in this case, the fibers  20  are oriented substantially parallel to one another, in order to minimize pressure drop therepast. 
     The fibers  20  are impregnated with a fuel vapor-adsorbing compound, as discussed herein in connection with the filter  10  of FIGS. 1-7. 
     SIXTH EMBODIMENT 
     Referring now to FIG. 13, another filter assembly  610  is shown, in accordance with a sixth embodiment of the invention. In the embodiment of FIG. 13, the filter  610  includes a support member  612 , which is a substantially funnel-shaped body. The support member  612  is divided along a central plane into two halves  607 ,  608 , respectively, and hinged at  609  for placement in an intake air flow passage  615 , associated with an internal combustion engine (not shown). These funnel halves  607 , 608  may be made foraminous or solid, as desired, according to the application. The funnel halves  607 , 608  are hingedly attached, at  609 , to the structural component which contains the air flow passage  615  therein, so as to be movable between an open position when the engine is running, and a closed position when the engine is off. A plurality of individual wicking fibers  20  are threaded through, or otherwise attached to the support member  612 . 
     The fibers  20  which are associated with the support member  612  are the same as previously discussed in connection with the first embodiment. 
     The fibers  20  are impregnated with a fuel vapor-adsorbing compound, as discussed herein in connection with the filter  10  of FIGS. 1-7. 
     SEVENTH EMBODIMENT 
     Referring now to FIG. 14, another filter assembly  710  is shown, in accordance with a seventh embodiment of the invention. In the embodiment of FIG. 14, the filter  710  includes an annular support band  714  which fits into the air flow passage  715 . The filter  710  also includes a plurality of parallel fiber strands  703 , which are connected at the upper ends thereof to the support band  714 , and hang freely at the other. 
     The fibers  703  which are associated with the support member  612  are the same as the fibers  20  previously discussed in connection with the first embodiment, except that they are arranged in a substantially parallel array. 
     The fiber strands  703  are impregnated with a fuel vapor-adsorbing compound, as discussed herein in connection with the filter  10  of FIGS. 1-7. 
     EIGHTH EMBODIMENT 
     Referring now to FIG. 15, another filter  810  for adsorbing fuel vapors is shown, in accordance with an eighth embodiment of the invention. In the embodiment of FIG. 15, the filter is made up primarily of a nonwoven fiber mat  812 , which includes a plurality of individual fibers  20 . 
     In forming the filter  810 , the fiber mat  812  is rolled up into a spiral configuration, as shown, and is inserted into an intake air flow passage  815 , associated with an internal combustion engine (not shown). The filter  810  may be placed in a flow passage such as a portion of an intake manifold. 
     The filter  810  may, optionally, also include a plurality of spacer members  814  attached to the fiber mat  812  to ensure that open air space is maintained between sections of the rolled-up fiber mat. The inclusion of the spacer members  814 , where used, helps make sure that the back pressure across the filter  810  remains at an acceptable level. 
     The fibers  20  making up the fiber mat  812  are the same as previously discussed in connection with the first embodiment. 
     The fibers  20  are impregnated with a fuel vapor-adsorbing compound, as discussed herein in connection with the filter  10  of FIGS. 1-7. 
     NINTH EMBODIMENT 
     Referring now to FIG. 16, another filter  910  is shown, in accordance with a ninth embodiment of the invention. In the embodiment of FIG. 16, the filter  910  includes a foraminous screen  912  having a plurality of fiber strands  903  attached to the screen at one end thereof. The fiber strands are connected a first end thereof to the screen  912 , as noted, and hang freely at the other. In this embodiment of a filter  910 , the fiber strands  903  are substantially parallel to one another, in order to minimize pressure drop across the filter. 
     The filter  910  is provided for placement in an intake air flow passage  915 , associated with an internal combustion engine (not shown). The filter assembly  910  may be placed in a flow passage such as a portion of an intake manifold. 
     The fibers  903  which are associated with the screen  912  are the same as the fibers  20  previously discussed in connection with the first embodiment, except that they are arranged in a substantially parallel array. 
     The fiber strands  903  are each impregnated with a fuel vapor-adsorbing compound, as discussed herein in connection with the filter  10  of FIGS. 1-7. 
     TENTH EMBODIMENT 
     Referring now to FIG. 17, another filter assembly  1010  is shown, in accordance with a tenth embodiment of the invention. In the embodiment of FIG. 17, a disc-shaped filter element  1011 , divided into wedge-shaped pieces, is affixed to an inner surface of a structural component containing an air flow passage  1015 . Each of the wedge-shaped (wedges), such as the adjacent wedges  1006 ,  1008  is made up of a nonwoven fiber web made up of a plurality of individual fibers  20 . 
     In this embodiment, in a manner similar to the first embodiment, the filter element  1011  may be attached to an annular support band  1016 , similar to the band  16  shown in FIG. 2 in connection with the first embodiment. Alternatively, the filter element  1011  may be attached directly to the inner surface of the structural component containing the air flow passage  1015 . 
     The individual wedges such as those shown at  1006 ,  1008  are not attached to one another at the side edges thereof. When air is flowing through the air flow passage  1015 , it can push the tips of the wedges apart from one another, and flow through the center of the filter, but when air flow stops, the tips of the wedges will tend to move back together. The filter  1010  is mounted in the air flow passage  1015  so as to open when the engine is running, and to close when the engine is off. 
     The individual fibers  20  making up the filter element  1011  are the same as previously discussed in connection with the filter  10  according to the first embodiment. 
     The fibers  20  are impregnated with a fuel vapor-adsorbing compound, as discussed herein in connection with the filter  10  of FIGS. 1-7. 
     ELEVENTH EMBODIMENT 
     Referring now to FIG. 18, another filter assembly  1110  is shown, in accordance with an eleventh embodiment of the invention. In the embodiment of FIG. 18, the filter  1110  is provided in the form of a conical filter element  1111 , for placement in an intake air flow passage  1115 . The cone-shaped filter element  111  includes a foraminous conical screen  1114 . 
     A plurality of individual wicking fibers  20  are threaded through, or otherwise attached to the screen  1114 , and these individual fibers are the same as the fibers  20  previously discussed in connection with the filter  10  according to the first embodiment. 
     The fibers  20  are impregnated with a fuel vapor-adsorbing compound, as discussed herein in connection with the filter  10  of FIGS. 1-7. 
     TWELFTH EMBODIMENT 
     Referring now to FIG. 19, another filter assembly  1210  is shown, in accordance with a twelfth embodiment of the invention. In the embodiment of FIG. 19, the filter  1210  includes a liquid-filled reservoir  1212 , filled with a non-volatile organic liquid such as a mineral oil or paraffin oil, and a plurality of individual wicking fibers  1203  arranged in a parallel array. The fibers  1203  are arranged with one end thereof in the reservoir  1212 , and the other end extending across an airflow passage  1215  in a structural component of a vehicle intake system. The filter assembly  1210  may be placed at the end of a flow passage such as a portion of an intake manifold. 
     The fibers  1203  are the same as the fibers  20  previously discussed in connection with the first embodiment, except that they are arranged in a substantially parallel array. 
     THIRTEENTH EMBODIMENT 
     Referring now to FIG. 20, another filter assembly  1310  is shown, in accordance with a thirteenth embodiment of the invention. In the embodiment of FIG. 20, the disc-shaped filter element  1311  includes a nonwoven fiber web  1312 . The fiber web  1312  is formed from a plurality of individual wicking fibers  20 . The upper end  1316  of the filter element  1311  is swingably attached to an inner surface of the structural element containing the air flow passage  1315 , while the lower end  1318  thereof is unattached and is allowed to move freely in the flow passage, as indicated by the two-headed arrow in the drawing. 
     The filter assembly  1310  may be placed in a flow passage such as a portion of an intake manifold. When air is flowing through the flow passage  1315 , it will tend to push the filter element  1311  inwardly, and will be allowed to pass below and around the lower end  1318 . When no air is flowing through the flow passage  1315 , the filter element  1311  will tend to drop down to a position blocking the flow passage. This permits the filter  1310  to have less effective pressure drop than a filter which stays in place in the passage. 
     The individual fibers making up the fiber web  1312  are the same as the fibers  20  previously discussed in connection with the filter  10  according to the first embodiment. 
     The fibers  20  are impregnated with a fuel vapor-adsorbing compound, as discussed herein in connection with the filter  10  of FIGS. 1-7. 
     FOURTEENTH EMBODIMENT 
     Referring now to FIG. 21, a vapor-adsorbent filter in accordance with a fourteenth embodiment of the present invention is shown generally at  1410 . 
     The filter  1410  is provided for placement in an intake airflow passage  1415 , associated with an internal combustion engine (not shown). The filter  1410  is shown attached to a side wall of a neck portion of an intake manifold  1404 , downstream of a throttle plate  1406  which is housed in a conventional throttle body  1408 . 
     The filter  1410  includes a filter element  1411 , which comprises a porous non-woven fiber web  1412  made up of a plurality of individual fibers  20  (FIG.  3 ). It will be understood from a review of FIG. 21 that the filter element  1411 , in this embodiment, has an arcuate cross-sectional shape, when a cross-section thereof is taken along a plane parallel to the throttle plate  1406  in its closed position. In the filter element  1411 , since the fiber web  1412  is placed along the side wall of the air flow passage  1415 , it will have a minimal impact on air flow therepast, and will not create a barrier to decrease engine performance. 
     The filter  1410  of this embodiment will be exposed to the environment inside the intake manifold downstream of the throttle plate  1406 . Therefore, the filter  1410  will still be effective to remove fuel vapors from the air inside the intake manifold  1404  after the engine is shut off and the throttle plate is closed. 
     Optionally, if desired, the filter  1410  may include a reinforcing frame member  1414 , such as the peripheral frame  1416  shown in FIG. 22, attached to and surrounding the fiber web  1412 , in order to provide support thereto, and to provide a solid member for engaging a side wall of the air flow passage  1415 . Alternatively, the filter element  1411  may consist primarily of a fiber web  1412 , adapted to be attached to the inner surface of the structural element  1404  defining the air flow passage  1415 . 
     Although the present invention has been described herein with respect to a preferred embodiment thereof, the foregoing description is intended to be illustrative, and not restrictive. Those skilled in the art will realize that many modifications of the preferred embodiment could be made which would be operable. All such modifications which are within the scope of the claims are intended to be within the scope and spirit of the present invention.