Abstract:
A filtering apparatus and method of operating a filtering device are disclosed. The apparatus includes a housing having an inlet and an outlet and at least first and second cavities that are coupled to the inlet and outlet, respectively, where an input fluid within the first cavity has an input pressure and an output fluid within the second cavity has an output pressure. The apparatus additionally includes a filter supported within the housing, where at least a portion of the filter extends along an axis within the housing, and the filter at least partly separates the cavities from one another. The apparatus further includes a device capable of determining whether the input pressure exceeds the output pressure by an amount and providing an indication thereof, the device being supported by the housing and extending into the housing along the axis and at least partly into a void within the filter.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to filtering devices that filter oil or other fluids, and more particularly relates to such filtering devices that are used in internal combustion engines.  
       BACKGROUND OF THE INVENTION  
       [0002]     Filtering devices are used in a variety of capacities in internal combustion engines such as those employed in vehicles, generators, and other applications. Because filters typically deteriorate over time, due to the clogging of the filters with dirt and other materials as fluid passes through the filters, the filters must be replaced with a relatively high frequency. This is true both with respect to filters for oil, hydraulic fluid, water, and other liquids, as well as for air filters and other types of filters.  
         [0003]     As a result, filtering devices commonly are designed to allow for easy replacement of the filters within such filtering devices or, in other circumstances, to allow for easy replacement of the entire filtering devices. With respect to the latter class of filtering devices in particular, it is typically desirable for the filtering devices to be not only easily removable but also compact. By making the filtering device compact, it is easier and more convenient for technicians and consumers to obtain and install replacement filtering devices, and also easier to design the engines on which the filtering devices are to be mounted to allow for easy coupling of the filtering devices to the engines.  
         [0004]     Because of the relatively rapid deterioration of the filters within filtering devices, and because it is desirable for the best performance of the engines with which the filtering devices are employed that the filtering devices operate properly, it is desirable that technicians and/or consumers be able to readily determine whether the filtering devices are in fact operating properly. In particular, it is desirable that technicians and/or consumers be able to readily determine whether the filters within the filtering devices have become excessively clogged. Because filtering devices of this type are designed to be entirely replaced, the filters within those filtering devices often are not readily accessible for visual inspection and, in any case, visual inspection is often not a reliable or easy way of determining whether filters are excessively clogged.  
         [0005]     In relation to this objective, some engines (particularly engines intended to be fixed in place rather than on mobile vehicles) are equipped with a filter status indicator that employs a pressure-sensitive device that is in communication with the fluid flowing into and out of the filtering device. The pressure-sensitive device is capable of detecting whether a pressure differential between the inflowing and outflowing fluid has become excessive, which is an indication of whether the pressure differential across the filter within the filtering device has become excessive. This in turn can serve as an indication of whether the filter has become excessively clogged since, when the filter becomes clogged, less oil passes through the filter and consequently the oil pressure on the filtered side of the filter is lessened and/or the oil pressure on the unfiltered side increases.  
         [0006]     In many conventional embodiments, the filter status indicator not only includes a pressure-sensitive device but further includes a moving portion such as a shaft that changes in position depending upon the pressure differential and, based upon its position, provides a visible indication of the pressure differential across the filter within the filtering device. Exemplary conventional filter status indicators that are used in conjunction with oil filtering devices are shown in, for example, U.S. Pat. Nos. 3,150,633; 4,139,466; 4,654,140; and 4,783,256, which respectively issued to Holl, Rosaen, Chen, and Cooper et al., respectively, on Sep. 29, 1964, Feb. 13, 1979, Mar. 31, 1987, and Nov. 8, 1988, respectively, each of which is hereby incorporated by reference herein.  
         [0007]     Although a variety of conventional engines have such filter status indicators for determining the status of filters within removable/add-on filtering devices, such conventional engine arrangements have several disadvantages. To begin, the filter status indicators should be positioned close to the locations at which the filtering devices are coupled to the engines, both in order to improve the accuracy of the pressure sensing performed by the filter status indicators and to make it evident that the filter status indicators actually pertain to the filtering devices. However, positioning of the filter status indicators close to the filtering devices can be problematic because the filter status indicators tend to require a significant amount of premium space within the engines.  
         [0008]     Further, in order to make it possible for the filter status indicators to be positioned close to the filtering devices, as well as to facilitate the installation and removal of the filtering devices in relation to the filter status indicators and the rest of the engines, the filter status indicators often must take on complicated structural configurations so that the filter status indicators do not obstruct or excessively restrict positioning, installation and removal of the filtering devices. Filter status indicators having these complicated structural configurations can be both difficult to design and expensive to manufacture.  
         [0009]     Therefore it would be advantageous if a new engine arrangement employing a filtering device and a filter status indicator could be developed, where the filter status indicator did not take up as much space within the engine and had a less complicated structural form than in conventional arrangements. Additionally, it would be advantageous if the new filtering device did not obstruct or inhibit the assembly and removal of filtering devices with respect to an engine. Further, it would be advantageous if the filtering device still was capable of accurately determining and providing a clear indication of filter status and, in particular, an indication when a filter has become excessively clogged.  
       SUMMARY OF THE INVENTION  
       [0010]     The present inventors have recognized that filter status indicators could be advantageously positioned on the replaceable filtering devices themselves rather than separate from those filtering devices on the engines on which the filtering devices are mounted. Additionally, the present inventors have recognized that cylindrical filtering devices employing tubular filters have relatively large cavities within the center of the filters that, while intended to be filled with filtered fluid, could also be at least partly filled with other materials and/or devices.  
         [0011]     In particular, the present inventors have recognized that a filter stats indicator having a pressure differential sensing device could be partly, largely, or even entirely positioned within the cylindrical cavity of a cylindrical filtering device. By mounting the pressure differential sensing device within the cylindrical cavity, the filtering device including the pressure differential sensing device does not need to be larger (or at least does not need to be much larger) than a filtering device without the pressure differential sensing device, nor does the general outside shape of the filtering device need to be substantially modified in order to accommodate the inclusion of the pressure differential sensing device.  
         [0012]     In particular, the present invention relates to a filtering apparatus. The filtering apparatus includes a first cylindrical housing having first and second ends, and further including a fluid inlet and a fluid outlet, and additionally a tubular filter supported within the first cylindrical housing and having outer and inner cylindrical surfaces. An outer region that receives input fluid from the inlet exists in between the outer cylindrical surface and the first cylindrical housing, an inner region that provides filtered fluid to the outlet exists within the inner cylindrical surface, the input fluid becomes the filtered fluid upon passing through the tubular filter, and the respective input and filtered fluids within the respective outer and inner regions experience outer and inner fluid pressures, respectively. The filtering apparatus further includes a device extending from the second end of the first cylindrical housing inward into the first cylindrical housing and at least partly into the inner region, where the device includes a second cylindrical housing, a biasing member, and an additional housing portion that is movable in relation to the second cylindrical housing. Respective internal surfaces of the additional housing portion and the second cylindrical housing at least partly define a cavity. A channel links the cavity to the inner region so that at least some of the filtered fluid enters the cavity and so that the internal surface of the additional housing portion experiences a first force due to the inner fluid pressure, an external surface of the additional housing portion is in fluid communication with the outer region so that the external surface experiences a second force due to the outer fluid pressure, and the biasing member applies a third force upon the additional housing portion tending to supplement the first force. The additional housing portion at least one of includes and is coupled to a protrusion that moves from a retracted position to an extended position in which the protrusion extends outward from the second end when the second force exceeds a threshold.  
         [0013]     Additionally, the present invention relates to a removable filtering apparatus for implementation in an engine, where the apparatus includes a housing and a filter supported within the housing. The housing has an inlet and an outlet and at least first and second cavities that are coupled to the inlet and the outlet, respectively, where an input fluid within the first cavity has an input fluid pressure and an output fluid within the second cavity has an output fluid pressure. At least a portion of the filter extends along an axis within the housing, and the filter at least partly separates the first and second cavities from one another. The filtering apparatus further includes a device capable of determining whether the input fluid pressure exceeds the output fluid pressure by a predetermined amount and providing an indication thereof, where the device is supported by the housing and extends into the housing along the axis and at least partly into a void within the filter.  
         [0014]     Further, the present invention relates to a method of operating a filtering device to provide an indication of when a filter within the filter device is excessively dirty. The method includes providing a housing within which is supported a filter, where at least a portion of the filter extends along an axis within the housing, where the filter at least partly separates first and second cavities within the housing containing input fluid and filtered fluid, respectively, and where an input fluid pressure is experienced within the first cavity and a filtered fluid pressure is experienced within the second cavity. The method further includes providing a component capable of determining whether the input fluid pressure exceeds the filtered fluid pressure by a predetermined amount, where the component is supported by the housing and extends into the housing along the axis and at least partly alongside the filter. The method additionally includes operating the component to perform filtering, and experiencing a change in at least one of the input fluid pressure and the filtered fluid pressure that results in the input fluid pressure exceeding the filtered fluid pressure by at least the predetermined amount. The method also includes providing an indication at the component that the input fluid pressure exceeds the filtered fluid pressure by at least the predetermined amount. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a cross-sectional view of an exemplary filtering device in accordance with one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]     Referring to  FIG. 1 , an exemplary filtering device  10  in accordance with one embodiment of the present invention is shown. The filtering device  10  in the present embodiment is intended to be used to filter oil or other lubricant, although in other embodiments the filtering device (or variations thereof) can be used to filter water or other fluids as well. As shown, the filtering device  10  includes a cylindrical housing or canister  15  with one or more input ports  20  and an output port  25  at a first end  30 , and a central orifice  35  at a second end  40 . Supported within the canister  15  is a tubular oil filter  45 . Further, in accordance with one embodiment of the present invention, a filter status indicator  50  is additionally supported by the canister  15 . As described in further detail below, the filter status indicator  50  operates to determine whether the oil filter  45  is excessively dirty or clogged and is capable of providing an indication thereof.  
         [0017]     More particularly, as shown, within the canister  15  are first and second support structures  55  and  60 , each of which generally is of the shape of a top-hat having a respective rim portion and a respective cylindrical portion  70  including a hole  75  at its center (as shown in  FIG. 1 , the top-hat-shaped support structures are both inverted). The oil filter  45  is supported between the rim portions  65  of the two support structures  55 ,  60 , which interface first and second annular ends of the oil filter  45 . The cylindrical portion  70  of the first support structure  55  extends away from the oil filter  45  to interface the first end  30  of the filtering device  10 , while the cylindrical portion of the second support structure  60  extends partly into a cylindrical cavity  80  defined by the inner cylindrical surface of the tubular oil filter  45  or, in some embodiments, defined by an additional cylindrical perforated wall surface (not shown) positioned along the inner cylindrical surface of the filter.  
         [0018]     The filtering device  10  is capable of being easily installed and removed with respect to an engine (not shown), and in the present embodiment is installed by rotating the filtering device so that a threaded female interface  27  at the first end  30  engages a complementary male interface (not shown) of the engine. In other embodiments, the filtering device  10  can be coupled/decoupled with respect to the engine by way of other structures and techniques known to those of ordinary skill in the art. The filtering device  10  generally operates as follows to clean/filter oil as it is provided to the filtering device (typically from the crankcase of an engine, not shown). To begin, unfiltered (or prefiltered) oil  85 , which typically is dirty and in need of filtering, enters the generally cylindrical filtering device  10  by way of the input ports  20  at the first end  30  of the filtering device. The unfiltered oil  85 , upon entering the input ports  20 , proceeds to enter a cavity  90  that concentrically surrounds the tubular oil filter  45  that is supported within the filtering device  10 .  
         [0019]     During normal operation, the unfiltered oil  85  then flows from the cavity  90  through the oil filter  45  into the cylindrical cavity  80  within the oil filter. Due to the filtering performed by the oil filter  45  as the oil passes through it, the oil within the cylindrical cavity  80  is filtered (or “clean”) oil  95 . From the cylindrical cavity  80 , the filtered oil  95  is able to exit the oil filter  45  by way of the output port  25 .  
         [0020]     Additionally as shown, although the input port  20  and the output port  25  are both located at the first end  30  of the oil filter device  10 , the two ports are separated from one another by the rim portion  65  and cylindrical portion  70  of the first support structure  55 . The output port  25  is formed at least in part by the hole  75  of the first support structure  55 , and the input ports  20  are located concentrically around the cylindrical portion  70  and lead to an annular region  100  existing between the canister  15  itself and the cylindrical portion  70  and rim portion  65  of the first support structure  55 . The annular region  100  generally is an extension of the cavity  90  that is concentric about the cylindrical portion  70  rather than around the oil filter  45 .  
         [0021]     Further with respect to the filter status indicator  50 , that component generally takes the form of an additional cylindrical canister  105 . A first end  110  of the filter status indicator  50  is supported by an inner edge  115  of the central orifice  35  at the second end  40  of the oil filter device  10  by way of a first grommet seal  117 . From the inner edge  115  and first grommet seal  117 , the filter status indicator  50  extends further inward into the filtering device  10  and in particular extends into the cylindrical portion  70  of the second support structure  60  up to the hole  75  at the support structure&#39;s center at the end of the cylindrical portion (e.g., at the bottom of the support structure as shown in  FIG. 1 ). A second end  135  of the filter status indicator  50  is supported by the cylindrical portion  70  of the second support structure  60  within the hole  75  by way of a second grommet seal  122 . The filter status indicator  50  generally extends inward along a central axis  120  of the filtering device  10 .  
         [0022]     The filter status indicator  50  includes a cylindrical housing portion  125  within which is an inner chamber  130  and an end plate portion  132  that snaps/clips onto the cylindrical housing portion  125  at the second end  135  by way of several clips  137  on the housing portion. Additionally, extending axially through the filter status indicator  50  from the first end  110  through the housing portion  125  and through a central opening  155  within the end plate portion  132  at the second end  135 , is a central piston  140  that is capable of moving axially along the central axis  120  in relation to the housing and end plate portions  125 ,  132 . The central piston  140  includes a flange portion  175  that extends radially outward from a central shaft portion  180  of the piston toward housing portion  125 . An o-ring seal  145  is positioned within a groove  150  along the circumference of the flange portion  175  and is wedged between the flange portion and the housing portion  125 , thereby sealing the inner chamber  130  from an annular region  160  existing between the flange portion and the end plate portion  132 . The central piston  140  is biased toward the cylindrical cavity  80  of the filtering device  10  (e.g., biased downward as shown in  FIG. 1 ) by an internal spring  145  positioned within the housing portion  125  as well as by any pressure provided by any filtered oil  95  that is contained within the inner chamber  130  as discussed further below.  
         [0023]     The o-ring seal  145  is preferably a low-drag seal to avoid creating excessive drag upon movement of the piston  140 . Nevertheless, the internal spring  145  in part is preferably designed to accommodate any resistance created by the o-ring seal  145 . In one embodiment, the spring provides a force of 7 lbs. In alternate embodiments, the other types of seals can be used in place of the o-ring seal  145  or other structures can be employed to seal the inner chamber  130  from the annular region  160 ; for example, a flexible diaphragm (not shown) can be coupled between the flange portion  132  and the housing portion  125 .  
         [0024]     As shown, an additional region  170  that is in fluid communication with the cavity  90  exists in between the cylindrical portion  70  of the support structure  60  and the filter status indicator  50 . Further, the annular region  160  is in fluid communication with the additional region  170  by way of a plurality of channels  165  extending through the housing portion  125 . Consequently, the annular region  160  is filled with some of the unfiltered oil  85 . At the same time, the end plate portion  132  in combination with the second grommet seal  122  seals off the additional region  170  from the cylindrical cavity  80 , which would otherwise be in fluid communication via the hole  75  in the cylindrical portion  70  of the second support structure  60 . The end plate portion  132  in particular is held tight against the second grommet seal  122  by way of an additional spring  167  extending between a lip  85  of the housing portion  125  proximate the first end  110  and the end plate itself at the second end  135 . Use of the additional spring  167 , which tends to press the end plate portion  132  away from the housing portion  125  despite the clips  137  linking those two portions, allows the sealing of the end plate portion  132  in relation to the second grommet seal  122  to be tight even though there may be slight variations in the tolerances/stack height of components within the filtering device, e.g., variation in the distance between the first and second grommet seals  117  and  122 , respectively.  
         [0025]     Further, first and second lip seals  245  and  250  are positioned within respective first and second recesses  247  and  252  of the end plate portion  132  and the housing portion  125  to interface the central shaft portion  180  of the piston  140 . By virtue of these respective lip seals  245  and  250 , unfiltered oil  85  is prevented from flowing from the annular region  160  along the shaft portion  180  and into the cylindrical cavity  80 , and also filtered oil  95  is prevented from flowing up and along the shaft portion from the inner chamber  130  and out of the filtering device  10 .  
         [0026]     Further as shown, the piston  140  includes a channel  190  extending from a first end surface  195  of the piston that is adjacent the cylindrical cavity  80  to a side surface  200  of the piston that is adjacent the inner chamber  130 . In the embodiment shown, the channel  190  actually includes a first portion  205  extending axially along the central axis  120  and a second portion  210  that crosses the first portion and extends radially outward to the side surface  200  (thus, the channel  190  can be formed simply by drilling two holes), although in alternate embodiments the exact shape of the channel could vary from that shown. The channel  190  allows the filtered oil  95  to flow freely from the cylindrical cavity  80  to the inner chamber  130  so that the filtered oil pressures within the cavity and chamber are identical (or at least approximately equal).  
         [0027]     Although the unfiltered oil  85  is sealed off from the inner chamber  130  by way of the flange portion  175  and the o-ring seal  145 , the unfiltered oil nevertheless is communicated within the additional region  170  and into the annular region  160 , and consequently provides pressure upon the flange portion and the seal. If the force applied to the flange portion  175  and o-ring seal  145  by the unfiltered oil  85  (plus a small amount of force applied by the filtered oil  95  of the cylindrical cavity  80  to the first end surface  195  of the piston  140 ) exceeds the force applied to the flange portion and seal by the filtered oil  95  within the inner chamber  130  (plus whatever drag force is imparted by the o-ring seal interfacing the housing portion  125 ) by a specific amount determined by the force applied by the spring  145 , then the piston  140  is forced away from the cylindrical cavity  80  (in the embodiment shown, forced upwards). Such can occur when the oil filter  45  is excessively clogged such that it does not allow oil to sufficiently easily pass through it.  
         [0028]     As the piston  140  is forced upwards, a top  215  of the piston is exposed as an indication that the oil filter  45  is excessively dirty/clogged, such that the oil filtering device  10  (or at least the filter itself) should be changed. In some embodiments, a color of a second end surface  212  of the top  215  of the piston matches that of the surrounding portions of the top of the filtering device  10  (e.g., black) while a side surface  217  of the top has a different color (e.g., red) such that exposure of the top is readily apparent.  
         [0029]     Further as shown, the filter status indicator  50  includes a latching mechanism  220  that locks when the piston  140  is urged sufficiently upward and the top  215  becomes sufficiently exposed, in order to lock the piston in place so that it cannot return to its retracted position (e.g., move back toward the cavity  80 ) even though the pressure differential between the unfiltered oil  85  and filtered oil  95  might later fall to an acceptable level. In the present embodiment, the latching mechanism  220  is formed by the interaction of a recess or indentation  225  on the shaft portion  180  of the piston  140  proximate the piston&#39;s top  215  and a third lip seal  230  positioned within an additional recess  235  within the housing portion  125  proximate the first end  110 , through which the piston passes. The third seal  230  is oriented opposite the orientation of the second seal  250 , such that, as the piston  140  moves sufficiently upward, the lip seal  230  juts into the recess  235  and then prevents the recess from returning back below the seal. In alternate embodiments, other latching mechanisms than that shown can be employed.  
         [0030]     Additionally, in a preferred embodiment, a temperature sensitive material  255  is positioned along the shaft portion  180  of the piston  140 , in this embodiment in between the second and third lip seals  250  and  230 . The temperature sensitive material  255  expands and contracts with different temperatures such that, if the temperature becomes too cold (e.g., below 180° F.), the temperature sensitive material expands to prevent movement of the piston  140 , and if the temperature becomes sufficiently warm (e.g., 180° F. or above), the material contracts and allows piston movement. This is advantageous since, in certain circumstances in which the temperature is low (for example, due to a cold starting temperature of the engine), the pressure differential between the filtered and unfiltered oil can be large even though the filter  45  does not need to be changed. A variety of different temperature sensitive materials can be employed depending upon the embodiment such as, for example, wax. In the embodiment shown, the temperature sensitive material can be inserted into position between the second and third seals  250 ,  230  via a channel  260  through the piston  140  extending from the second end surface  212  to a portion of the side surface  217  located between those two lip seals. Once the material is added, a cap  262  is used to close off the channel  260 .  
         [0031]     While the foregoing specification illustrates and describes the preferred embodiments of this invention, it is to be understood that the invention is not limited to the precise construction herein disclosed. The invention can be embodied in other specific forms without departing from the spirit or essential attributes. For example, although the invention as discussed above pertains to oil filters, the invention also could be employed in relation to other filtering devices for filtering other fluids such as hydraulic fluids, transmission fluids, water, etc. as well as air.  
         [0032]     Also, other configurations performing the same overall functions could also be employed. For example, in one alternate embodiment, a piston could be mounted for movement that was generally perpendicular to the central axis  120  within an oil filter status indicator that was largely positioned within the cylindrical cavity  80  but not entirely, such that the piston could extend along the second end  40  (e.g., perpendicular to the central axis) and be extended/retracted out of and into an orifice within the side (cylindrical) outer surface of the oil filter device  10 . Also, in certain embodiments, a bypass or pressure relief valve can be included within the filtering device to relieve/prevent excessive build-ups of pressure within the device.  
         [0033]     Accordingly, reference should be made to the following claims, rather than to the foregoing specification, as indicating the scope of the invention.