Abstract:
A filter element includes a panel construction of filter media; a filter frame holds a periphery of the panel construction; and a bypass arrangement is adjacent to the panel construction. The bypass arrangement includes a door moveable between a closed position and an open position, and a force member holding the door in the closed position until restriction across the filter media reaches a predetermined amount to allow the door to move to the open position. An example force member is a magnet arrangement or a spring. The element is installable in an air cleaner assembly. A method of filtering air directs a flow of air into a housing holding a panel filter element, and prevents bypassing of the filter element by having a bypass door remain closed by exerting a first closing force on the bypass door. The method further includes a step of opening the bypass door, when the restriction across the panel filter element causes a second force that exceeds the first closing force, to allow air flow to bypass the panel filter element and flow through an opening exposed by the door.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to filtration of fluid systems. In particular, this disclosure concerns filtration of air in an arrangement that includes a bypass door moveable between a closed position and an open position. 
       BACKGROUND 
       [0002]    Filtration of air is important in order to remove particulate material from the air flow stream. This is important in situations in which the air flow stream is used in downstream equipment such as engines, compressors, and generators. Filtration of air is also important in closed environments, such as closed cabins in airplanes or helicopters. 
         [0003]    Filtration usually involves having filter media to allow for air to pass through the media while the media catches the particulate material. Over time, and if used in environments where there is much dust or other particulate material in the air, the media will become occluded. When this happens, the pressure drop across the filter media increases. Restriction of air flow through the media increases. When restriction increases, less air is allowed to flow through the media and to the downstream equipment. The reduced amount of air flow getting to the downstream equipment can cause operational problems in the downstream equipment. Thus, it is desirable to have a system in which the air is allowed to bypass the media if the restriction increases to an unacceptably high level. 
       SUMMARY OF THE DISCLOSURE 
       [0004]    In accordance with principles of this disclosure, a filter element is provided. The filter element includes a panel construction of filter media having an upstream flow face and an opposite downstream flow face. A bypass arrangement is adjacent to the panel construction. The bypass arrangement includes a door moveable between a closed position and an open position, and a force member holding the door in the closed position until restriction across the filter media reaches a predetermined amount to allow the door to move to the open position. 
         [0005]    In one example embodiment, the door extends a length of the filter media and is hingedly connected to the bypass frame. 
         [0006]    In one embodiment, the force member comprises a magnet arrangement holding the door in the closed position until the restriction across the filter media reaches the predetermined amount. 
         [0007]    In one example embodiment, the bypass arrangement is at an end of the filter media, while in another embodiment, the bypass arrangement is between two sections of filter media. 
         [0008]    In another aspect, an air cleaner assembly is provided. The air cleaner assembly includes a housing having a housing wall defining an interior, an inlet for receiving air to be filtered, and an outlet for exhausting filtered air. A filter element is operably mounted and sealed within the interior of the housing. The filter element includes a panel construction of filter media oriented in the interior such that air flows from the inlet, through an upstream flow face, through the filter media, out through the downstream flow face, and then through the outlet. A bypass arrangement is provided and includes a door moveable between a closed position, which closes an air flow bypass opening, and an open position which exposes an air flow bypass opening. The closed position blocks air flow through the bypass opening, the open position permits air flow through the bypass opening. A force member holds the door in the closed position until restriction across the filter media reaches a predetermined amount to allow the door to move to the open position permitting air to bypass the filter media and flow through the bypass opening. 
         [0009]    In another aspect, a method of filtering air comprises directing a flow of air into a housing holding a panel filter element, and preventing bypassing of the filter element by having a bypass door remain closed by exerting a first closing force on the bypass door. The method further includes a step of opening the bypass door, when the restriction across the panel filter element causes a second force that exceeds the first closing force, to allow air flow to bypass the panel filter element and flow through an opening exposed by the door. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a front elevational view of a filter element constructed according to principles of this disclosure; 
           [0011]      FIG. 2  is a right side elevational view of the filter element of  FIG. 1 ; 
           [0012]      FIG. 3  is a bottom plan view of the element of  FIG. 1 ; 
           [0013]      FIG. 4  is a schematic perspective view with parts broken away, of the filter element of  FIGS. 1-3 ; 
           [0014]      FIG. 5  is a rear elevational view of a door assembly utilized in the filter element of  FIGS. 1-4 ; 
           [0015]      FIG. 6  is a bottom plan view of the door assembly of  FIG. 5 ; 
           [0016]      FIG. 7  is a left side elevational view of the door assembly of  FIG. 5 ; 
           [0017]      FIG. 8  is a schematic side elevational view of an air cleaner utilizing the filter element of  FIGS. 1-4 ; 
           [0018]      FIG. 9  is a front elevational view of an alternate embodiment of a filter element constructed according to principles of this disclosure; and 
           [0019]      FIGS. 10A and 10B  are schematic views depicting an alternate embodiment of a force member and door in the bypass arrangement. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    One embodiment of a filter element is illustrated in  FIG. 1  at  10 . The filter element  10  includes filter media  12  having an upstream flow face  14  and an opposite downstream flow face  16 . In the embodiment shown, the media  12  is embodied in the form of a panel construction  18 , such that the fluid flow is in a straight direction and does not need to turn a corner. 
         [0021]    A variety of types of filter media  12  are usable. Such media can include depth media, pleated media or Z-media. By the term “Z-media”, it is meant filter media having a plurality of flutes, each flute having an end adjacent the upstream flow face and adjacent to the downstream flow face, with selected flutes being closed adjacent to the upstream flow face while being open adjacent to the downstream flow face, and selected flutes being open adjacent to the upstream flow face while being closed adjacent to the downstream flow face. The flutes can be straight, tapered, or darted. Examples of filter elements with Z-media are found in, for example, U.S. Pat. No. 5,820,646; Patent Publication 2003/0121845; and U.S. Pat. No. 6,350,291, each of these patent documents being incorporated by reference herein. Whatever type of media is utilized, the media may also include micro or nano-fibers, such as fibers described in U.S. Pat. Nos. 6,673,136, 6,974,490, 7,090,712, 7,270,692, 6,743,273, 6,924,028, 7,270,693, 7,070,640 &amp; 7,179,317, incorporated herein by reference. 
         [0022]    In the particular embodiment illustrated, the media  12  is depicted as pleated media. The pleated media can be made out of whatever type of material is best usable for the fluid being filtered, and in many applications, will be cellulose. The pleat depth, again, will be selected based upon the particular system in which it is filtering, including rated air flow, desired restriction, and desired filter life. Usable examples, include, for example, media with a pleat depth of 0.5-3 inches, for example 1.25-1.75 inches. 
         [0023]    The filter media  12  can have an outer periphery selected to best fit the system which it is being used in. In the embodiment shown, the panel construction  18  of filter media  12  is embodied as a trapezoid. Other shapes are usable. 
         [0024]    In accordance with principles of this disclosure, the filter media  10  includes a filter frame holding a periphery of the panel construction. In the embodiment shown, the filter frame  20  holds the periphery of the filter media  12 . The filter frame  20  can include a single frame member  21  that is bent to surround the periphery, or it include a plurality of separate and distinct frame pieces  21  connected together to hold the media  12 . The embodiment shown includes four frame pieces at  21 ,  22 ,  23 , and  24 . Each frame piece  21 - 24  can be embodied in many different structures, but in the embodiment shown, each frame piece  21 - 24  has a C-shaped cross section, including a base  26  with a pair of arms  27 ,  28  ( FIG. 4 ). In the embodiment shown, frame pieces  21  and  23  are parallel to each other and also parallel to the direction of the pleats  19 . Frame piece  21  is longer than frame piece  23 , although in other embodiments, they could be of equal length or piece  21  could be shorter than piece  23 . In the embodiment shown, frame pieces  22  and  24  are not parallel to each other and are angled relative to the frame pieces  21  and  23  and also angled relative to the direction to the pleats  19 . 
         [0025]    As can be seen in the embodiment of  FIG. 4 , the media  12  is held within the frame pieces  21 - 24  by being secured to the base  26  between the arms  27 ,  28 . The media  12  can be secured to the frame pieces  21 - 24  through a variety of mechanisms such as by adhesive, by potting, by urethane, or by other suitable techniques. The frame member  20  including frame pieces  21 - 24  can be made from a variety of materials including metal, such as aluminum, steel, or combinations thereof. 
         [0026]    In the embodiment shown, the filter frame  20  has a same outer periphery as the filter media  12 . As such, in the embodiment shown, the filter frame  20  forms a trapezoid. 
         [0027]    In accordance with principles of this disclosure, the filter element  10  includes a bypass arrangement that remains closed until restriction across the filter media reaches a predetermined amount, and then opens to permit air to bypass the filter media  12  and flow through a bypass opening. In preferred arrangements, the bypass arrangement  30  includes a door  32  moveable between a closed position ( FIG. 1 ) and an open position ( FIG. 4 ). In preferred arrangements, the bypass arrangement  30  further includes a force member that holds the door  32  in the closed position until restriction across the filter media  12  reaches a predetermined amount to allow the door  32  to move to the open position. The bypass arrangement  30  will be adjacent to the filter media  12 . By “adjacent” it is meant that the bypass arrangement can be located any convenient place within the filter element  10 , such as between sections of filter media or at various ends. In one example embodiment shown in  FIG. 9 , the bypass arrangement  30  is located between two sections of filter media  12 , including being centered between the two sections of media ( FIG. 9 , discussed further below). In another illustrated embodiment, shown in  FIGS. 1-4 , the bypass arrangement  30  is located at an end of the panel construction  18 , and in particular, adjacent to frame piece  22 . 
         [0028]    In the embodiment shown, the door  32  is shown as a generally flat, straight structure that is oriented relative to the rest of the filter element  10  to allow it to move between its closed position and open position. In the embodiment shown, the bypass arrangement  30  includes a bypass frame  36  secured to the filter frame  20 ; and a gasket arrangement  37 . 
         [0029]    The gasket arrangement  37  generally helps to provide a seal between the bypass frame  36  and the door  32 . In the embodiment shown, the gasket arrangement  37  is depicted as a picture-frame style rectangular gasket  38  defining an open aperture  40 . The aperture  40 , defined by the border of the gasket  38  functions as a bypass opening  42 . The door  32  is moveable from the closed position ( FIG. 1 ) in which the door  32  blocks the bypass opening  42 , and an open position ( FIG. 4 ), in which the bypass opening  42  is exposed. In preferred arrangements, the cross-sectional area of the bypass opening  42  will be at least 4%, and typically 6-7% of the overall cross-sectional area of the upstream flow face  14  of the media  12 . It will typically be no greater than 10% of the area of the upstream flow face  14  of the media  12 . As can be seen in  FIG. 4 , the bypass opening  42  can extend between 80%-110% of the length of the media  12 . The door  32  will preferably be made from metal, such as steel, because it cooperates with the force member, described below. 
         [0030]    The door  32  can be made moveable relative to the bypass frame  36  in a variety of mechanisms. In the embodiment shown in  FIG. 4 , the door  32  is moveable relative to the gasket  38  by a hinge connection  46  to allow pivoting motion of the door  32  relative to the pivot axis  48  defined by the hinged connection  46 . 
         [0031]    The bypass frame  36  includes a bypass panel assembly  50 . The gasket  38 , in the embodiment shown, is held by the bypass panel assembly  50  through adhesive and other such ways. Panel assembly  50  can also include end piece  54  forming an end  56  of the bypass arrangement  30 . 
         [0032]    In accordance with principles of this disclosure, the bypass arrangement  30  includes a force member  58  holding the door  32  in the closed position until the restriction across the filter media  12  reaches a predetermined amount to allow the door  32  to be in the open position exposing the bypass opening  42 . While a variety of mechanisms can be used, in the embodiment shown, the force member  58  comprises a magnet arrangement  60 . The magnet arrangement  60  holds the door by use of having a magnetic field exposed to the metal door  32 . The magnetic field of the magnet arrangement  60  attracts the door  32  against the gasket  38  to block the bypass opening  42 . In the embodiment shown, the magnet arrangement  60  includes at least one magnet  61  secured to the bypass frame  36 . In this specific embodiment shown, the magnet arrangement  60  includes four magnets  61 ,  62 ,  63 , and  64  secured to the panel assembly  50 . 
         [0033]    In the embodiment shown, the magnets  61 - 64  are oriented to be in direct contact with the door  32 . The magnets  61 - 64  attract the door  32  and hold it securely against the gasket  38  to hold the door  32  in a position that blocks the bypass opening  42 . 
         [0034]    In use, the magnet arrangement  60  exerts a certain, predetermined force on the door  32  to hold it to a closed position. When air flows across the filter media  12 , eventually the media will become blocked or occluded, increasing the restriction across the media. Eventually, for a certain rated air flow, the force by the air on the upstream flow face  14  of the filter media  12  will increase to a level in which it is greater than the force exerted by the magnet arrangement  60  holding the door  32  closed. At this point, the force will cause the door  32  to pivot along the pivot axis  48  on the hinge connection  46 , moving the door  32  away from the gasket  38  to expose the bypass opening  42 . This will then allow air to flow through the bypass opening  42 . 
         [0035]    The force member  38  could be other structures, including springs such as a leaf spring  160  ( FIGS. 10A and 10B ). In  FIGS. 10A and 10B , an alternate embodiment of bypass arrangement  30 ′ includes as the force member  38 , leaf spring  160  to apply a force on door  32 . In  FIG. 10A , the door  32  is in the closed position, being held there by spring  160 . In  FIG. 10B , it can be seen how the leaf spring  160  has deflected and was forced in a flatter position as the door  32  was forced over the spring  160 , when the door  32  moved to the open position. 
         [0036]    Although springs, such as the leaf spring  160  can be used, magnet arrangement  60  has been found to be desirable because once the threshold pressure drop is reached to cause the door  32  to move away from the gasket  38  to expose the opening  42 , there is no longer a significant force trying to pull the door  32  back to the closed position, as would be the case with a spring. Alternatively, with certain types of springs (such as leaf spring  160 ), once the threshold pressure drop is reached, triggering the door  32  to expose the opening  42 , the spring  160  and door  32  would need to be “re-set” after triggering—in other words, the door  32  would need to be physically pushed back to the closed position over leaf spring  160  from the position of  FIG. 10B  to the position of  FIG. 10A . By using the magnet arrangement  60 , there are advantages over springs in that there is no significant “spring force” that would be trying to pull the door  32  back toward the gasket  38  to the closed position after opening, and there is no need to re-set the magnet arrangement  60  after the door  32  moves to the open position. 
         [0037]    Filter element  10  further includes filter gasket  70 . The gasket  70  is for providing a seal between the filter element  10  and a housing  80  ( FIG. 8 ) in which the filter element  10  is installed. In preferred embodiments, the gasket  70  is secured to the filter frame  20 . As can be seen in  FIGS. 2 ,  3 , and  4 , the gasket  70  is secured to at least frame pieces  21 ,  23 , and  24 . In the embodiment shown, the gasket  70  is also secured to end of piece  54  of the bypass frame  36 . The function of the gasket  70  is to provide a seal between the filter element  10  and the housing  80  in which it is installed so that air to be filtered cannot bypass the filter element  10  by flowing between a space between the element  10  and the housing  80 . 
         [0038]      FIG. 9  shows element  10 ′ with the bypass arrangement  30  located adjacent to the filter media  12 , by being located between first and second sections  113 ,  114  of media  12 . In the  FIG. 9  embodiment, the filter element  10 ′ can be otherwise constructed analogously as the element  10  of  FIGS. 1-4 , including frame  20 . In the  FIG. 9  embodiment, the bypass arrangement  30  is approximately centered between the media sections  113 ,  114 , but in other embodiments, the bypass arrangement can be located at any place within the element  10 . In the  FIG. 9  embodiment, because of the relatively symmetrical arrangement, the restriction across the media  12  and the door  32  is more evenly distributed than the embodiment of  FIGS. 1-4  and can be useful when even distribution of restriction is an important factor. 
         [0039]    In  FIG. 8 , an air cleaner assembly  78  includes the filter housing  80  with the filter element  10  removably and replaceably installed within. The element  10  is depicted in hidden lines, shown installed within an interior  82  of the housing  80 . The housing  80  includes a housing wall  84  defining the interior  82 . Housing  80  includes a housing inlet  86  for receiving air to be filtered and an outlet  88  for exhausting filtered air. The filter element  10  is installed in the housing interior  84  between the inlet  86  and outlet  88 . The housing  80  also includes a service cover  90  that allows the interior  82  of the housing  80  to be accessed in order to change the filter element  10  when the filter life has been reached. The air cleaner assembly  78  can be used to clean air upstream of equipment such as a compressor, or an engine, for example. 
         [0040]    In use, air to be filtered enters the housing inlet  86 , flows through the upstream flow face  14  of the element  10 , to the downstream flow face  16  of the element  10  and then out through the outlet  88  of the housing  80 . When restriction across the filter media  12  exceeds a predetermined amount, the force impacting the media  12  will exceed the force being exerted by force member  38 , such as the magnet arrangement  60 . This will allow the bypass arrangement  30  to open the door  32  exposing the bypass opening  42 . The bypass arrangement  30  will move from the closed position to the open position and the pressure across the filter element  10  including the door  32 , reaches a predetermined value, such as about 24-26 inches of water. A typical rated air flow will be about 605 CFM. Once the pressure again drops, the door  32  will return to the closed position, blocking the bypass opening  42  and will be held closed by the magnet arrangement  60 . If leaf spring  160  is used, the user will physically push the door  32  over the leaf spring  160  from the open position to the closed position, blocking the bypass opening  42  to “re-set” the door  32  and spring  160 .