Abstract:
A hydrocarbon trapping device including an adsorbing element of a material configured to adsorb hydrocarbons from the air and a support connected to the adsorbing element is provided. The adsorbing element includes first and second opposing ends, and the support includes an embedded portion located within the adsorbing element between the first and second ends to reinforce the adsorbing element.

Description:
BACKGROUND  
       [0001]     1. Field of Invention  
         [0002]     The present invention relates generally to an air intake system and more particularly to a hydrocarbon trap for adsorbing hydrocarbons in the air intake system.  
         [0003]     2. Related Technology  
         [0004]     Due to laws requiring the reduction of the levels of hydrocarbons that vehicles may emit into the atmosphere, it is necessary for automotive designers to include systems in vehicles to control emissions. Hydrocarbons are released in a vehicle&#39;s exhaust, as well as from the engine, even when it is not operating. Hydrocarbons remaining from engine reactions can leak out of the engine through the engine&#39;s air intake system. It is therefore beneficial to reduce the level of hydrocarbons released from both the exhaust and the engine via the air intake system.  
         [0005]     One device for retaining hydrocarbons from the air released through the engine&#39;s intake is a filter-like device having a hydrocarbon trapping element. Typically, the hydrocarbon trapping device is formed of monolith carbon that is disposed in the air induction system of a motor vehicle. More specifically, the hydrocarbon trapping device is typically located in an air intake conduit that provides air to the engine for combustion. Therefore, when the engine is operating and air is flowing through the conduit towards the engine, the hydrocarbon trapping device is considered to be upstream from the engine.  
         [0006]     The hydrocarbon trapping device operates by adsorbing hydrocarbons from the low velocity flow that occurs while the engine is not in operation. When the engine is not in operation air leaks out of the air intake system and into the atmosphere. During engine operation, high velocity flow through the air intake system purges the device of trapped hydrocarbons and flushes the hydrocarbons into the vehicle engine.  
         [0007]     One problem arising with the hydrocarbon trapping device, however, is that the adsorbing element can become saturated with hydrocarbons; substantially reducing or ceasing adsorption of hydrocarbons. Therefore, in order to effectively trap hydrocarbons and to substantially prevent saturation of the device, it is advantageous to increase the adsorption capacity of the hydrocarbon trapping device.  
         [0008]     Another problem associated with hydrocarbon trapping devices is that the devices may act as an obstruction to the air flowing to the engine, thus causing a pressure drop in the airflow to the engine. Therefore, in order to substantially reduce or prevent a drop in air pressure across the hydrocarbon trapping device, it is advantageous to increase the amount of air that can flow through the device.  
         [0009]     Yet another problem associated with hydrocarbon trapping devices is that the devices may not have the strength to sustain structural integrity during operation. This problem is especially evident in cases where the device includes a large cross-sectional area—such as a cross-sectional area designed to permit a large volume of air to flow therethrough.  
         [0010]     Therefore, it is highly desirable to have a hydrocarbon trapping device that is able to adsorb a relatively large amount of hydrocarbons without becoming saturated, while substantially preventing large airflow pressure drops and maintaining a sufficient structural strength throughout the life of the device.  
       SUMMARY  
       [0011]     A hydrocarbon trapping device embodying the principles of the present invention that includes an adsorbing element having a material configured to adsorb hydrocarbons from the air intake system, and further includes a support connected to the adsorbing element to provide structural support for the adsorbing element. The support includes an embedded portion located within the adsorbing element between first and second ends thereof. The support increases the strength of the adsorbing element and allows the adsorbing element to be constructed with a larger cross-sectional area. More specifically, the cross-sectional area of the adsorbing element can be increased by 100% or more while maintaining an effective strength.  
         [0012]     In one aspect of the invention, the support and the adsorbing element cooperate to form a press-fit engagement extending substantially along the entire length of the embedded portion. A pliable material, such as a fibrous mat, is located between the adsorbing element and the support to aid in forming the press-fit engagement. The embedded portion is preferably located within a central region of the adsorbing element. More preferably, it is located completely within the central region. In an alternative embodiment, the embedded portion extends from a central region of the adsorbing element to an outer surface of the adsorbing element.  
         [0013]     The support may include an end or ends that extend beyond the first and second ends of the adsorbing element. For aerodynamic purposes, the ends of the support include rounded outer surfaces.  
         [0014]     The hydrocarbon trapping device may also include a radially oriented strut having a first end engaging the support and a second end engaging the conduit of the air intake system.  
         [0015]     Accordingly, an air intake system of an engine can also be providing so as to include: a conduit, an adsorbing element located within the conduit, and a support connected to the adsorbing element. The adsorbing element adsorbs hydrocarbons present in the air intake system, and the support includes an embedded portion located within the adsorbing element between the first and second ends.  
         [0016]     In one embodiment, the conduit of the air intake system preferably includes a first portion having a first diameter and a second portion having a second, larger diameter, with the adsorbing element being located within the second portion. The dimensions of the first portion and the second portion are such that the potential airflow through the unobstructed first portion is substantially equal to the potential airflow through the second section, which will be partially obstructed by the adsorbing element.  
         [0017]     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is an end view of an air intake system in accordance with the teachings of the present invention, the air intake system having a conduit receiving a hydrocarbon trapping device;  
         [0019]      FIG. 2  is a cross-sectional view, generally taken along line  2 - 2 , of the air intake system in  FIG. 1 ;  
         [0020]      FIG. 3  is an end view of an alternative embodiment of an air intake system in accordance with the teachings of the present invention; and  
         [0021]      FIG. 4  is a cross-sectional view taken along line  4 - 4 , of the air intake system in  FIG. 3 . 
     
    
     DETAILED DESCRIPTION  
       [0022]     Referring now to the drawings,  FIG. 1  shows a portion of an air intake system  10  for an engine  11 , shown in block form, of a motor vehicle (not shown). The air intake system  10  is located between an air intake inlet  13  and the engine  11  such that a conduit of the air intake system  10  supplies ambient air via the inlet  13  to the engine  11 . The air intake system  10  includes a conduit  12  for supplying air to the engine  11 , and a hydrocarbon trap device  14 . Positioned within the conduit  12  as such, the hydrocarbon trap device  14  removes hydrocarbons from the air passing through the conduit  12 , particularly when the engine is not running.  
         [0023]     The hydrocarbon trap device  14  is preferably located between an inlet  13  of the air intake system  10  and the engine  11  of the motor vehicle. Therefore, while the engine  11  is operating under normal conditions and air is being drawn towards the engine  11  in a high velocity airflow direction  24 , the hydrocarbon trap device  14  is upstream from the engine  11 . In this situation, when the high velocity airflow is directed towards the engine  11 , any hydrocarbons in the air intake system are forced towards the engine  11  where they become combusted.  
         [0024]     However, when the engine  11  is not in operation, air is permitted to seep out of the inlet  13  of the air intake system  10  and into the atmosphere. Air seeping out of the engine  11  typically contains hydrocarbons, which the hydrocarbon trap device  14  substantially captures as discussed below, preventing the hydrocarbons from escaping to the ambient air. Once the engine  11  is operating again, the hydrocarbons are purged from the hydrocarbon trap device  14  by the relatively high-velocity airflow flowing towards the engine  11 , where they become combusted.  
         [0025]     As one of its main components, the hydrocarbon trap device  14  includes a hydrocarbon adsorbing element, such as the monolith  16  shown in  FIG. 1 . The monolith  16  is a generally cylindrical-shaped carbon element having a plurality of channels  18  defined therein. The channels  18  are aligned such as to be generally parallel with a central axis  22  of the conduit  12  and to be generally parallel with the high velocity airflow direction  24 . This configuration, where the channels  18  are generally parallel with the high velocity airflow direction  24 , minimizes the pressure drop that the airflow undergoes as it flows through the monolith  16  at a high velocity, thus maximizing the air flow to the engine  11 .  
         [0026]     Walls  20  of the monolith  12  define the channels  18 , which are shown having a generally rectangular cross-section. While shown with a rectangular cross-section, any appropriate configuration such as a circular cross-section, may be used as the shape of the channels  18 .  
         [0027]     In order to substantially prevent the hydrocarbon trap device  14  from becoming saturated with hydrocarbons, it is preferred that the monolith walls  20  define as large a surface area as possible. One means for increasing the surface area volume is to provide a monolith with a relatively large cross-sectional diameter  26 , as shown in  FIG. 1 . The large cross-sectional diameter  26  is particularly advantageous because it permits a relatively large amount of air to flow therethrough. Furthermore, an increased cross-sectional diameter  26  allows the length of the monolith  16 , along the longitudinal axis  22 , to be reduced, thereby reducing the length along which the air flow is constricted as it passes through the monolith  16 .  
         [0028]     However, the increased cross-sectional diameter  26  and the reduced length may cause decreased strength within the monolith  16 , especially in a central region  28  of the monolith  16 . As used herein, the central region  28  is defined as the portion of the monolith  16  located in the area adjacent to the longitudinal axis  22 . More specifically, the arcuate line defining the central region  28  shown in  FIG. 1  preferably has a diameter that is one-half or less in size than the diameter of the monolith  16 .  
         [0029]     The conduit  12  includes a portion having a diameter large enough to receive the hydrocarbon trap device  14 . Therefore, the conduit  12  in  FIGS. 1-2  includes an increased diameter portion  14   a  having a first diameter  31 , and decreased diameter portions  14   b  having a second diameter  33  that is smaller than the first diameter  31 . The conduit  12  also includes sloping portions  14   c  that gradually slope between the respective increased and decreased diameter portions  14   a ,  14   b  in order to promote a smooth airflow through the respective portions  14   a ,  14   b ,  14   c . The conduit  12  is preferably a unitary, one-piece tube in order to minimize airflow turbulence. However, a multi-piece tube may alternatively be used to potentially simplify the manufacturing process.  
         [0030]     In order to improve the strength of the monolith  16 , a support  30  is preferably provided within the monolith  16 . More specifically, the support  30  includes an embedded portion  32  (shown in  FIG. 1 ) located within the monolith  16  and extending between a front face  34  and a rear face  36  of the monolith  16 . The embedded portion  32  is located in the central region  28 , in order to most effectively provide support for the hydrocarbon trap device  14  and may be formed from plastic or any other suitable material.  
         [0031]     The support  30  preferably is mounted within an opening  38 , defined by the monolith walls  20 , in a press-fit connection. Therefore, the opening  38  is shaped to compliment the support  30 . Furthermore, a pliable intermediate member, such as a cushion  40 , is located between the opening  38  and the support  30  in order to protect the respective components  30 ,  38  during assembly and to more effectively seal the components  30 ,  38  with each other. The cushion  40  may be formed from any appropriate material, such as a fibrous mat. Additionally, a mechanical fastener or an adhesive may be provided between the support  30 , the cushion  40 , and the opening  38  in order to more effectively secure the components  30 ,  38 ,  40  together.  
         [0032]     As seen in  FIG. 2 , the support  30  extends completely through the length  41  of the monolith  16  such that a front end  42  extends from the front face  34 , and a rear end  44  extends from the rear face  36 . The front end  42  has an aerodynamic surface in order to smoothly deviate air in a radial direction towards the monolith  16 , thus minimizing turbulence in the air flowing into the hydrocarbon trap device  14 . More specifically, the front end  42  includes a generally rounded outer surface  46  and a generally rounded nose section  48 . The nose section  48  may be a unitary portion of the front end  42 , or it may be a separate piece that is integrally formed with the front end  42 .  
         [0033]     The rear end  44  is similarly provided within an aerodynamic surface to smoothly transition the air towards the central portion of the conduit  12 , thus minimizing turbulence in the air flowing out of the hydrocarbon trap device  14 . The rear end  44  preferably has a diameter  50   a ,  50   b  that decreases as it extends away from the monolith  16 . More preferably, the rear end  44  includes a generally cone-shaped outer surface  52 .  
         [0034]     In order to securely position the support  30 , a support member is preferably provided, such as a strut  54   a  having a first end  56  engaging the support  30  and a second end  58  engaging the conduit  12 . More preferably, a plurality of struts  54   a ,  54   b ,  54   c ,  54   d  are provided to secure the support  30  at various points around its circumference. Similarly to the support  30 , the struts  54   a ,  54   b ,  54   c ,  54   d  shown in  FIGS. 1-2  include an aerodynamic outer surface to minimize turbulence flowing into the hydrocarbon trap device  14 . The struts  54   a ,  54   b ,  54   c ,  54   d  each have a generally teardrop-shaped cross-sectional profile. The struts  54   a ,  54   b ,  54   c ,  54   d  may be formed of the same material as the support  30 .  
         [0035]     As shown in  FIG. 2 , the struts  54   a ,  54   b ,  54   c ,  54   d  are spaced apart from the monolith  16  along the longitudinal axis  22  in order to avoid obstructing the monolith channels  18 . In order to more effectively position the support for the support  30 , the struts  54   a ,  54   b ,  54   c ,  54   d  are secured to either or both of the support  30  and the conduit  12  by securing means, such as fasteners or adhesives. Alternatively, the struts  54   a ,  54   b ,  54   c ,  54   d  are press-fit between the support  30  and the conduit  12 , without the aid of any additional securing means.  
         [0036]     A process by which the air intake system  10  shown in  FIGS. 1-2  is manufactured will now be discussed. The conduit  12  may be a unitary, one-piece tube formed by any appropriate means. For example, the tube may be formed by: selectively enlarging a constant-diameter tube section in order to form the sloping portions  14   c  and increased diameter portion  14   a ; selectively decreasing a constant-diameter tube section in order to form the sloping portions  14   c  and decreased diameter portion  14   b ; molding a material into a tube having the respective portions  14   a ,  14   b ,  14   c ; or a combination thereof. The tube portions may be reduced or enlarged by any appropriate means, such as swaging or blow molding.  
         [0037]     Alternatively, the conduit  12  may include multiple sections that are individually formed, and then integrally connected with each other. The sections may be connected by any appropriate means, such as welding or adhering the sections together.  
         [0038]     The hydrocarbon trap device  14  shown in  FIGS. 1-2  is preferably manufactured by removing material from the central region  28  of the monolith  16  in order to form the opening  38 . The step of removing material may be done by any appropriate means, such as machining the monolith  16 . Alternatively, the monolith  16  may be initially formed having an opening  38 , such as by molding or extruding.  
         [0039]     The support  30  shown in  FIGS. 1-2  is preferably manufactured by forming a plastic component into the desired shape by any appropriate means, such as molding or machining. As discussed above, the nose section  48  may be a unitary component of the support  30 , or it may be a separate piece that is integrally connected to the support  30 . The struts  54   a ,  54   b ,  54   c ,  54   d  may also be a unitary component of the support  30 , or they may be a separate piece that is positioned to engage the support or to be integrally connected to the support  30 .  
         [0040]     Next, the cushion  40  is wrapped around the embedded portion  32  of the support  30 , and the support  30  and the struts  54   a ,  54   b ,  54   c ,  54   d  are preferably press-fit into the opening  38 . As discussed above, a securing means, such as a fastener or an adhesive may be used to secure the respective components  16 ,  30 ,  54   a ,  54   b ,  54   c ,  54   d  together.  
         [0041]     Referring now to  FIGS. 3 and 4 , an alternative embodiment of an air intake system  110  embodying the principles of the present invention will now be discussed. A hydrocarbon trap device  114 , having a monolith  116 , is received within a conduit  112  having a longitudinal axis  122 , similarly with the embodiment described with respect to  FIGS. 1-2 . Additionally, the monolith  116  includes a plurality of channels  118  defined by monolith walls  120  in order to receive airflow. As the air flows from the engine  11  in a low velocity airflow direction  125 , the hydrocarbon trap device  114  traps pollutants within, thereby removing them from the air. As the air flows towards the engine  11  at a high velocity airflow direction  124 , the hydrocarbon trap device  114  is purged of pollutants.  
         [0042]     The air intake system  110  shown in  FIGS. 3 and 4  also includes a support  130  at least partially embedded within the monolith  116  in order to strengthen the hydrocarbon trap device  114 . The support  130  preferably includes a plurality of arm portions  130   a ,  130   b ,  130   c ,  130   d  extending generally from a central region  128  of the monolith  116  to an outer surface  161  of the monolith  116 . The central region  128  is defined as the portion of the monolith  116  located a relatively short distance from the longitudinal axis  122  along a line generally perpendicular thereto, as shown in  FIG. 3 . More specifically, the arcuate line defining the central region  128  in  FIG. 3  preferably has a diameter that is one-half or less the size of the diameter of the monolith  116 . The outer surface  161  is defined as the portion of the monolith  116  engaged with the conduit  112 . Each of the arm portions  130   a ,  130   b ,  130   c ,  130   d  preferably includes an embedded portion  132  embedded within the monolith  116 , thereby increasing its strength. The embedded portion  132  is secured within a guide channel  162  by an appropriate process, such as a press-fit connection of a securing means.  
         [0043]     Each of the arm portions  130   a ,  130   b ,  130   c ,  130   d  also preferably includes an end  142  extending from a front face  134  of the monolith  116 . The end  142  preferably includes an aerodynamic outer surface, such as a rounded nose portion  164 .  
         [0044]     Alternative embodiments other than those described above may be used with the present invention. For example, the hydrocarbon trap may be positioned downstream from the operating engine  11  such as to filter pollutants from the engine exhaust. Additionally, the adsorbing element may be formed from an alternative material than described above. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.