Abstract:
A T-handle for a filter includes an integral mechanical indicator. The T-handle indicator has a threaded portion that extends through a hole in the filter cover and retains the cover to a canister. The indicator includes a spring-biased button that provides a visual indication of whether the element needs to be replaced. The button is received in a body that is open to the pressure on the downstream side of the filter element. A pair of clips on the button engage the indicator body to retain the button in the inward (element change) position. The clips can be accessed when the T-handle indicator is removed from the filter to return the button to the outward (fresh element) position. The indicator button includes an axially-elongated slot extending radially through the button, and the body includes a corresponding pair of holes on opposite sides of the slot. A handle rod for rotating the T-handle projects through the holes in the body, and the button is constrained by the rod as the button slides within the body.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to filters for fluid filtration.  
         BACKGROUND OF THE INVENTION  
         [0002]    A filter is typically provided in a fluid system to remove particulate and other contaminants before the fluid reaches a sensitive component, such as a combustion chamber, pump, compressor, etc. Many times the filter incorporates an element that is replaceable, such that a spent element can be replaced with a fresh element. The operator can either remember to change the element after, e.g., a certain number of operating hours or miles (in the case of an automobile); and/or electronic and mechanical sensors can be provided to visually or audibly notify an operator of the need for a filter change.  
           [0003]    Examples of mechanical indicators for filters are shown in U.S. Pat. Nos. 3,068,831 and 3,812,816. In these references, a button is slideably received in a body. The body has an internal chamber that is open to the clean (downstream) side of the element. The button is normally spring-biased into an outward (clean element) position which can be confirmed by visually inspecting the button. When the media becomes clogged, the pressure on the downstream side of the element decreases as the system attempts to pull fluid through the filter. When the pressure decreases above the force of the spring (which can be appropriately chosen), the button is pulled inwardly into the body. The difference in the button position can alert the operator to an element change. The button and/or body can also incorporate colors, which visually change as the button is retracted to facilitate identifying the need for an element change. A clip, tab or other device on the button can engage the body to maintain the button in its retracted position when the engine or fluid system is shut-down to facilitate confirming the location of the button. The button can then be reset when the element is changed.  
           [0004]    The mechanical indicator can be located at a number of different locations on the housing. One common location is in the cover of the canister. The indicator, however, must share space with other devices mounted to the cover. With a trend toward smaller filters, space can be at a premium in many applications. In addition, some covers are attached to the filter canister by a T-handle (see, e.g., U.S. Pat. No. 3,493,110). The T-handle has a threaded portion that extends through an opening in the cover and screws down into a central tubular member or standpipe projecting from the opposite end of the canister. Such a T-handle allows easy attachment and removal of a cover, but limits the ability to mount other devices on the cover, as the outwardly-projecting handle must be free from obstruction in order to grasp and rotate the handle.  
           [0005]    U.S. Pat. No. 3,493,110 shows a mechanical indicator and a T-handle located on the cover of a filter. The indicator has a rotating pointer and is mounted separately from the handle. While the indicator has a low profile such that the handle can be rotated, Applicants believe the operator&#39;s hand can still encounter the indicator if the operator is not careful, and it can be burdensome and somewhat uncomfortable to rotate the handle to remove and attach the cover.  
           [0006]    Applicants believe most mechanical indicators have heretofore been a component separate from the T-handle. One reason may be that the mechanical indicator has included complex, somewhat fragile components which are necessary to provide accurate and repeatable sensing of pressure. Such components typically cannot withstand abuse or repeated handling. The handle, on the other hand, must be a robust component able to withstand repeated grasping and turning by the operator. It is believed these contrasting requirements have necessitated mounting the indicator separately from the handle.  
           [0007]    Applicants thereby believe there is a demand for an improved mechanical indicator, particularly useful with filters incorporating T-handles, which overcomes many, if not all, of the drawbacks noted above.  
         SUMMARY OF THE PRESENT INVENTION  
         [0008]    The present invention provides an improved mechanical indicator for a filter, which conserves space on the cover for the filter, and which does not interfere with the operation of a T-handle.  
           [0009]    According to the present invention, the mechanical indicator is incorporated into the T-handle as an integral indicator handle assembly. The indicator handle assembly includes a body with a handle portion and a mechanical indicator portion. The handle portion has a threaded collar that can be inserted through an opening in the cover and screwed down into a central standpipe in the filter. The handle portion further includes a handle rod supported transversely in the body to facilitate grasping and turning the indicator handle assembly.  
           [0010]    The mechanical indicator portion of the assembly includes a button that is normally spring-biased outwardly in the body to provide a visual indication that the element is fresh. The button is located in a central chamber of the body that is open to the downstream side of the filter element. When the element becomes spent during operation of the fluid system, the pressure on the downstream side of the element drops, which causes the button to move inwardly in the body against the spring. A pair of clips engage the indicator body as the button is retracted to retain the button in the inward (spent element) position. When the indicator handle assembly is unscrewed from the canister and removed during an element change, the clips can be squeezed together to allow the indicator button to move back to its normal (fresh element) position.  
           [0011]    A transparent cap is provided on the indicator body. The button can have a colored end that is visible through the cap to facilitate confirming the position of the button.  
           [0012]    The integral T-handle and mechanical indicator is robust and strong, and able to withstand repeated use. The assembly uses only few components, which minimize assembly time and effort, and which prolong the useful life of the handle indicator. Preferably the indicator button includes an axially elongated slot extending radially through the button, and the body includes a corresponding pair of circular openings on opposite sides of the slot. The handle rod projects through the openings in the body and through the slot in the button, and is retained in the openings such as by press-fit. The button is constrained by the movement of the rod in the slot as the button moves axially within the body. The handle rod thereby serves the dual function of i) rotating the indicator handle assembly, and ii) locating and guiding the indicator button.  
           [0013]    During assembly, a bias spring and wiper seal are first inserted through the upper open end the indicator body. A retainer cup can be provided to support the wiper seal. The button is then located in the body, with the clips of the button projecting downwardly into the threaded collar. The handle rod is then inserted radially through the openings in the indicator body, and through the slot in the button. The cap is then attached to the upper end of on the body to enclose the button, spring and wiper seal. The indicator handle assembly of the present invention is thereby easy to assemble, as well as to disassemble for inspection and repair.  
           [0014]    Thus, the integral indicator handle assembly combines the usefulness of a T-handle to allow attachment of a cover to a filter canister, with a mechanical indicator to provide an indication of when a filter element needs to be replaced. The device is robust and strong, and capable of long-term use.  
           [0015]    Further features of the present invention will become apparent to those skilled in the art upon reviewing the following specification and attached drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is an elevated perspective view of the indicator handle assembly of the present invention, shown attached to a filter;  
         [0017]    [0017]FIG. 2 is a cross-sectional side view of a portion of the indicator handle assembly and filter of FIG. 1;  
         [0018]    [0018]FIG. 3 is a cross-sectional enlarged side view of the indicator handle assembly, with the indicator shown in a fresh element position;  
         [0019]    [0019]FIG. 4 is a cross-sectional enlarged side view of the indicator handle assembly of FIG. 3, shown rotated ninety degrees;  
         [0020]    [0020]FIG. 5 is an exploded view of the indicator handle assembly;  
         [0021]    [0021]FIG. 6 is a cross-sectional enlarged side view of the indicator handle assembly similar to FIG. 3, with the indicator shown in a spent element position; and  
         [0022]    [0022]FIG. 7 is a cross-sectional enlarged side view of the indicator handle assembly of FIG. 6, shown rotated ninety degrees. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    Referring to the drawings, and initially to FIGS. 1 and 2, a filter is shown generally at  10  having a canister  11  with an open end  12  and a closed end  13 . The closed end of the canister preferably includes a removable cup-shaped collection bowl  14 . A disk-shaped cover  15  can be removably attached to the open end of the canister to allow easy access to a filter element  18 . Filter element  18  can be any type of element suitable for the particular application, and preferably has a generally ring-shaped media  19 , with end caps  20 ,  21  at either end. An inlet port  26  and outlet port  28  are provided in canister  12 , to direct fluid to be filtered into the canister, and to discharge filtered fluid from the canister.  
         [0024]    A central standpipe  32  is attached to and projects axially upwardly from the closed end  13  of the canister  11 , through the center of filter element  18 , and toward the open end  12 . The standpipe terminates at a distal free end  33 , which has an internal threaded portion  34 . An opening  35  is provided along the length of the standpipe. End caps  20 ,  21  of element  18  are sealed to the standpipe to fluidly seal the clean side of the element from the dirty side. The cover  15  for the canister has a central through bore or opening  36 , which generally corresponds to the location of the standpipe  32 , and which has a portion  37  with internal threads. Standpipe  32  preferably extends axially upwardly through a portion of bore  36 . An appropriate O-ring seal  39  is provided between the cover and the canister. While one exemplary type of canister, cover and element is shown and described, it is important to note that the filter could have many variations depending on the particular application. Resort may be had to U.S. Pat. No. 3,931,011, and to U.S. patent application Ser. No. 09/452,857 filed Dec. 3, 1999 for “Fuel filter With Keyed Latch Valve”, both of which are incorporated herein by reference, for further descriptions of the filter element and some of the internals of a filter canister that are appropriate for the present invention. It should be appreciated that the filter of the present invention is useful for many types of applications and is typically used to filter diesel fuel in automotive and truck applications.  
         [0025]    An indicator handle assembly, indicated generally at  40 , retains cover  15  to canister  12  and provides a visual indication of the need to replace a spent filter element. Referring now to FIGS.  3 - 5 , the indicator handle assembly  40  includes a cylindrical body  41 , and has a handle portion, indicated generally at  42 , and a mechanical indicator portion, indicated generally at  44 . The handle portion  42  includes an annular collar  45  that is formed in one piece with and extends axially downward from body  41 . Collar  45  has an outwardly threaded portion  46  which is dimensioned to be received within the inwardly-threaded standpipe  32 . A tapered shoulder  47  interconnects body  41  with collar  45 , and an O-ring seal  48  is provided around collar  45  against shoulder  47 .  
         [0026]    The handle portion  42  further includes a handle rod  50  which is supported transversely within the body  41  and can be easily grasped by the user to rotate the assembly, around its central axis. Preferably, body  41  is hollow and includes a central cylindrical chamber  52  which is connected to an internal cylindrical passage  53  extending through collar  45 . Handle rod  50  extends through a pair of diametrically opposite circular openings  54  formed in body  47 , and has a dimension (and geometry) such that the handle rod is closely and tightly held within the openings.  
         [0027]    To retain cover  15  on canister  12 , collar  45  is inserted through bore  36  in the cover and the handle rod  50  is rotated. The threaded portion  46  on collar  45  is screwed down through threaded portion  37  of cover  15  and through the threaded portion  34  of standpipe  32 . The collar is screwed down until the tapered shoulder  47  of body  46  is seated in opening  36  of the cover, and the cover is forced against the canister. O-ring seal  48  prevents fluid leakage between body  41  and cover  15 .  
         [0028]    A transparent cup-shaped cap  80  encloses the opposite upper end of body  46 . Cap  80  can be retained on body  45  in any appropriate manner, and is preferably removable. To this end, the cap  80  includes resilient fingers as at  81 , which closely receive the upper end of body  45 , and engage an annular channel  82  to retain the cap on the body. The cap can be easily removed from the body by grasping and pulling the cover upwardly away from the body. This makes it relatively easy to install or remove cap  80 , however, it should be appreciated that other attachment techniques (removeable and non-removeable) can be used, such as threads or a press-fit, to attach the cap to the body.  
         [0029]    The mechanical indicator portion  44  of the assembly includes an indicator button  60  closely and slideably received within chamber  52  of body  41 . Preferably, button  60  has an outer, somewhat cylindrical configuration, which closely matches the inside configuration of body  41 . The upper end of button  60  can include fins  83  (see FIG. 4) which are received within and guide the button within cap  80 . The finned upper end  64  of button  60  can be colored to facilitate readily ascertaining the position of the button through the cap.  
         [0030]    A post  68  projects axially downward from the lower end of button  60  through the central passage  53  in collar  45 . The post  68  separates into two elongated, axially-extending fingers  70 ,  71 , each of which has a tapered end  72 ,  73  and an outwardly-facing catch or tab  74 ,  75 , respectively.  
         [0031]    The tapered ends  72 ,  73  of fingers  70 ,  71  fit closely within a radially-inward directed annular lip  77  at the distal end of collar  45 . Lip  77  defines an opening  78  into passage  53 . Button  60  and post  68  are preferably formed together in one piece (unitary) from appropriate material, such as plastic.  
         [0032]    An annular, bi-directional wiper seal  85  is received around post  68 , and located against the lower surface of button  60 . Wiper seal  85  is closely received within body  45  and seals against the interior surface of the body as button  60  reciprocates within the body. An annular retainer washer  88  is also received around post  68 , and supports the lower end of wiper seal  85 . Wiper seal  85  and washer  88  are preferably retained by press-fit to post  68 .  
         [0033]    A compression spring  90  also surrounds post  68 , and extends between the lower inner surface of retainer washer  68  and the inwardly-projecting lip  77  of collar  45 . Spring  90  biases button  60  axially upwardly in body  46  into a “fresh element” position.  
         [0034]    Button  60  includes an axially-elongated slot  92  extending radially through the button, and which has only a slightly wider dimension than handle rod  50 . Handle rod  50  extends radially through slot  92  and orients and supports button  60  such that button  60  is rotationally fixed with respect to body  41  (i.e., such that the button has only an axial component of motion).  
         [0035]    When the indicator handle assembly  40  is assembled with filter  10 , that is when collar  45  is received in central standpipe  32 , and handle  50  is rotated by the operator to secure cover  15  on canister  10 , the central passage  53  in collar  45  is open and fluidly connected to the downstream (clean) side of filter element  18  through opening  35  in the standpipe. Normal operating pressure and the compression spring  90  keep button  60  in the fresh element position, with the button  60  supported against cap  80 . Since cap  80  is transparent, it is easy for an operator to visually confirm the location of the button.  
         [0036]    As the filter element  18  becomes spent, the pressure on the downstream side of the element decreases as the particulate matter is captured by the media and fluid flow is reduced through the element. When the pressure drops beyond a certain amount (which can be predetermined by the appropriate choice of compression spring), the button  60  is pulled downwardly within body  46  against spring  90 . Handle rod  50  prevents the button from rotating as the button moves axially within body  41 , which prevents damage to wiper seal  85 .  
         [0037]    As shown in FIGS. 6 and 7, when the button is pulled downwardly, fingers  70 ,  71  are pushed through opening  78 , with the tapered ends  72 ,  73  slightly compressing the fingers together until catches  74 ,  75  pass lip  77 . At this point, the fingers  70 ,  71  spring outwardly and the catches  74 ,  75  grasp annular lip  77  to retain the button in a “change element” position. The button is retained in this position even after the fuel system is shut down. As should be apparent in FIGS. 6 and 7, button  60  has moved away from transparent cap  80 , which allows the operator to easily visually confirm that the element needs to be changed.  
         [0038]    Upon removing the indicator handle assembly  40  by unscrewing the assembly from central standpipe  32 , the distal ends  72 ,  73  of spring fingers  70 ,  71  can be manually squeezed together to allow the catches  74 ,  75  to pass around lip  77 , and the button  60  to again move back to its “fresh element” position.  
         [0039]    Since the indicator handle assembly  40  is made of few parts, the manufacture of the assembly is simple and straight forward. The torquing force applied by handle rod  50  is absorbed by the housing  41 , thereby ensuring the indicator portion of the assembly has a long operating life.  
         [0040]    To assemble the indicator assembly  40 , the compression spring  90 , retainer washer  88  and wiper seal  85  are first located over central post  68 , and the button  60  is inserted into body  41 , with post  68  received in passage  53 . Next, handle rod  50  is inserted radially through openings  54  and through the elongated slot  92  in button  60 . Finally, cap  80  is attached to the opposite end of the indicator body  41  to enclose all the components in the body. To inspect or replace any of the components, cap  80  is removed and the above assembly process is reversed.  
         [0041]    The indicator handle assembly is thereby easy to assemble and to disassemble to inspect or replace components from the indicator assembly. While a mechanical indicator is described above and shown, it is possible that the indicator could be electrical or otherwise have non-mechanical components (such as Hall-effect devices). Such an indicator would also provide the function of indicating to the operator that a filter element needs to be replaced, while conserving space on the filter cover.  
         [0042]    Thus, as described above, the present invention provides an improved mechanical indicator for a filter, which conserves space on the cover for the filter, and which does not interfere with the operation of a T-handle.  
         [0043]    The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein should not, however, be construed as limited to the particular form described as it is to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the scope and spirit of the invention as set forth in the appended claims.