Patent Publication Number: US-9416758-B2

Title: Fuel filter

Description:
FIELD 
     The present application relates to devices and systems for conditioning the fuel of a diesel engine, including a fuel filter and a system wherein fuel flows of differing characteristics are directed to traverse a filter medium before mixing and passing through the filter medium. 
     BACKGROUND 
     Engines may be configured to operate using diesel fuels. There is typically, at least one fuel filter arranged in the fuel system to filter out particles which may be in the diesel fuel. A common issue with diesel fuel filters, in particular at low ambient temperatures, such as during an engine cold-start, is that wax may precipitate out of the diesel fuel. The precipitated wax may clog the fuel filter. The amount of wax that precipitates from the fuel may depend upon the fuel properties and ambient temperature the vehicle is started in. As such, the precipitated wax in the fuel may reduce the pressure of the fuel system, performance of the engine and, if severe enough, can cause damage to the fuel system. 
     Techniques to mitigate problems associated with precipitated wax clogging diesel fuel filters generally fall into one of two categories. One is to include a heating mechanism with the filter. Another is to recirculate some fuel warmed by the engine through the filter via a recirculation line. Both techniques have shortcomings, but approaches to mitigate diesel fuel filter clogging have mostly been limited to including a heating mechanism with the filter. 
     One example approach to providing a heating mechanism with the filter is disclosed in US Patent Publication 2003/0116490. The disclosure provides a heater element positioned between an annular outer surface of the filter assembly housing and the fuel filter. Fuel traveling through the fuel filter is heated by the heater element when the fuel temperature is below a predetermined temperature. 
     The inventors herein have recognized several issues with this approach. For example, the addition of a heating element to the filter may add cost and complexity. Another shortcoming with this approach is, like many similar approaches, it fails to address several shortcomings with the technique of recirculating fuel warmed by the engine back through the filter. The inventors herein have recognized that the warm return fuel from the engine tends to remains near the top of the filter and does not distribute to the lower portion. In effect, the warm fuel does not perform the function it is intended. Embodiments in accordance with the present disclosure address this shortcoming. 
     Embodiments may provide a fuel filter that may include a plurality of return fuel conduits axially traversing a filter medium. Each conduit may include an inlet in fluidic communication with the fuel recirculation passage. Each conduit may have a return fuel line exit port adjacent to a distal end of the filter medium. In this way, it is possible to provide better thermal management via the fuel filter. For example, by operating via a method that flows heated fuel down the length of the filter through sealed tubes, it is possible to heat a greater amount of the filter to reduce fuel gelling during cold starts, such as with regard to diesel fueled vehicles. 
     It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an example vehicle system layout, including details of a fuel system. 
         FIG. 2  is a sectional view illustrating selected details of a fuel filter in accordance with the present disclosure. 
         FIG. 3  is a sectional view taken at the line  3 - 3  of  FIG. 2 . 
         FIG. 4  is a sectional view similar to the view shown in  FIG. 3  but illustrating selected details of another example fuel filter in accordance with the present disclosure. 
         FIG. 5  is a perspective view of a fuel filter in accordance with the present disclosure showing exterior features thereof. 
         FIG. 6  is a perspective view of an insert that may be configured to fit inside the fuel filter illustrated in  FIG. 5 . 
         FIG. 7  is a top view of the insert as seen from direction indicated with section line  7 - 7  in  FIG. 2 . 
         FIG. 8  is a section view illustrating another example fuel filter in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description relates to systems and methods for diesel fuel conditioning.  FIG. 1  depicts an example vehicle system  100 . In the depicted embodiment, vehicle system  100  is a diesel-fuelled vehicle system. The driving force of the vehicle system  100  may be generated by engine  10 . Engine  10  may include one or two banks  14 . One bank  14  is indicated in the current example showing four cylinders  16 . While engine  10  is shown as a 4-cylinder, four-stroke engine, it will be appreciated that the engine may have a different cylinder configuration (for e.g., in-line, V-shaped, or opposed) and/or a different number of cylinders (e.g., six, or eight). 
     Engine  10  of the vehicle system  100  may include a fuel system  20 . Fuel system  20  may include a fuel rail  102 , a supply pump  104 , and fuel injectors  106 . Fuel rail  102  may provide a chamber for holding fuel for subsequent injection into cylinders  16  through fuel injectors  106 . In the depicted example, the fuel rail  102  may provide pressurized fuel to fuel injectors  106  of the bank  14  along high-pressure injector passages  108 . Fuel rail  102  may include one or more fuel rail pressure sensors/switches  126  for sensing fuel rail pressures (P fuel   _   rail ) and one or more fuel rail temperature sensors  128  for sensing fuel rail temperatures (T fuel   _   rail ) and communicating the same with an engine controller  12 . Only one fuel rail pressure sensor/switch  126  and one fuel rail temperature sensor  128  is shown for simplicity. Additional fuel rail pressure regulators may also be included. In the depicted example, fuel injectors  106  may be of the direct injection type, although it will be appreciated that they may alternately be of the port injection type. Further still, each cylinder  16  may include more than one injector, some of the injectors being of the direct injection type while others are of the port injection type. 
     Fuel may be pressurized by supply pump  104  and transferred to the fuel rail  102  along high-pressure rail passage  110 . In one example, supply pump  104  may be driven by the rotation of engine  10 , such as by an engine crankshaft and/or an engine camshaft. Alternatively, supply pump  104  may be driven by an optional electric motor. 
     A low pressure feed pump  112  may be configured to draw low-pressure fuel from fuel tank  114  via fuel inlet line  115 , to pump it to and through fuel filter  118 , and to the supply pump  104  via fuel outlet line  116 . The fuel may move through the fuel filter  118  due to the pumping action of one or both of the low pressure feed pump  112  and the supply pump  104 . As such, the fuel supplied to the supply pump, via the fuel filter  118 , may hereinafter also be referred to as the supply fuel. 
     Fuel rail  102  may also be configured to return fuel, and thereby reduce fuel pressure, into low pressure recirculation passage  120  via rail return flow passage  122 . A pressure reducing valve at the rail outlet (not shown) may regulate the return flow of fuel from the fuel rail into recirculation passage  120 . Similarly, fuel returned from injectors  106  may also be fed into recirculation passage  120  via injector return flow passage  124 . Supply pump  104  may also be configured to return fuel, and thereby reduce fuel pressure into recirculation passage  120  via pump return flow passage  130 . A pressure reducing valve at the pump&#39;s outlet (not shown) may regulate the return flow of fuel from the supply pump into the recirculation passage  120 . As such, the fuel returned from the supply pump, injectors, and/or rail may hereinafter also be referred to as the return fuel. The return fuel may be heated by one or more engine components, for example the bank  14  of cylinders  16 , or the fuel rail  102  and consequently be at a higher temperature than the supply fuel. The fuel recirculation passage  120  may include a return fuel line  136  coupled with the fuel recirculation passage  120  wherein the warmed return fuel is able to be directed through the fuel filter  118 . A fuel recirculation valve  134  may be configured to selectively direct selected amounts of the return fuel to the fuel filter  118 . 
       FIG. 2  is a sectional view illustrating selected details of an example fuel filter  118  in accordance with the present disclosure. The fuel filter  118  may be used in the system  100  illustrated in  FIG. 1 . The fuel filter  118  may include a plurality of return fuel conduits  150  axially traversing a filter medium  152 . Each conduit  150  may include an inlet  153  in fluidic communication with the fuel recirculation passage  120  via, for example the return fuel line  136 . In some embodiments each conduit  150  may be in direct fluidic communication with the fuel recirculation passage  120 . Various examples may, or may not include the fuel recirculation valve  134 . Each conduit  150  may have a return fuel line exit port  154  adjacent to a distal end  156  of the filter medium  152 . Each conduit  150  may have a cross section of any number shapes, for example circular, oval, semicircular, rectangular, etc. 
     The fuel filter  118  may include a container  158  for housing the filter medium  152 . There may be a fuel line conduit  160  axially traversing the filter medium  152 . The fuel line conduit  160  may include an inlet  162  in fluidic communication with the fuel inlet line  115 . The fuel line conduit  160  may also include a fuel line exit port  162  in fluidic communication with the plurality of return fuel line exit ports  154  to at least partially mix respective flows from the plurality of return fuel conduits  150  and the fuel line conduit  160  within the container  158  adjacent the distal end  156  of the filter medium  152 . In this way, more effective mixing of the supply fuel with the heated return fuel within the fuel filter  118  may be achieved. In this way, the fuel filter wax removal at the filter may be expedited and potential issues related to wax build-up at the filter medium  152  may be better addressed. 
     In some embodiments the return fuel line  136  may include an inlet coupling  166  and an outlet coupling  168 . The fuel filter  118  may include a volume  167  between the inlet coupling  166  and an outlet coupling  168 . The volume  167  may be various shapes, for example an elongated volume, or an annular shape. A temperature sensitive valve  170  may be operatively disposed between the inlet coupling  166  and the outlet coupling  168  and may be configured to direct at least part of a flow from the return fuel line  136  to the plurality of return fuel conduits  150  when a temperature of the flow is within a preselected range. In this way, in addition to, or instead of the fuel recirculation valve  134  described above which may selectively direct various amounts of the return fuel to the fuel filter  118 , additional control, or alternate control which may depend of the temperature of the return fuel may be achieved. Such control may, or may not, be operatively coupled with the controller  12 . 
     Embodiments may include a manifold  172  formed within the container  158  to receive the flow from the return fuel line  136  via the temperature sensitive valve  170  when the temperature of the flow is within the preselected range. The plurality of return fuel conduits  150  may be fluidically coupled with the manifold  172 . Some example embodiments may include two or more temperature sensitive valves  170  to control flow from the volume  167  and the manifold  172 . 
       FIG. 3  is a sectional view taken at the line  3 - 3  of  FIG. 2 . The figure illustrates an example wherein the plurality of return fuel conduits  150  may be six conduits  150 .  FIG. 4  is a sectional view showing another example embodiment having four return fuel conduits  150 . Various other embodiments may have various numbers of return fuel conduits. 
       FIG. 5  is a perspective view of a fuel filter  118  in accordance with the present disclosure showing exterior features thereof including the outside of the container  158 .  FIG. 6  is a perspective view of an insert  174  that may be configured to fit inside the fuel filter  118  illustrated in  FIG. 5 . The insert  174  may be configured to fit within the container  158 , and may also be configured to at least partially support the filter medium  152  in an annular configuration. The fuel line conduit  160  may be centrally located within and may axially traverse the insert  174 . The fuel line conduit may having a fuel line exit port  162  in fluidic communication with the plurality of return fuel line exit ports  154  adjacent a distal end  176  of the container  158 . Referring now again to  FIGS. 2-4 ; the insert  174  may form an annular channel outlet  178  radially outside the fuel line conduit  160 , and radially inside the filter medium  152 . 
     Various embodiments may include a fuel filter  118  including a container  158 , and a filter membrane  152  in the container  158 . The fuel filter  118  may also include conduits  150  extending from inlets  153  located adjacent to a first end  180  of the container to outlets  154  located adjacent to a second end  176  of the container  158  to direct two flows of differing temperatures from the first end  180  to the second end  176  to at least partially thermally mix the two flows near the second end  176  before passing a mixed flow through the filter membrane  152 . 
     Referring again to  FIG. 1 , one of the two flows is a first flow  182 , represented with an arrow from a fuel tank  114 . Another of the two flows may be a second flow  184 , also represented with an arrow, from a recirculation line  120  made relatively warmer than the first flow  182  by heat from one or more engine components, for example the combustion chamber(s) of the internal combustion engine  10 , or the fuel rail, or the like, which may be heated indirectly from the heat of combustion. In some cases return flow fuel may be heated via other means, for example by a heater. 
     The fuel filter  118  may also include an annular manifold  172  located within the first end  180  of the container  158 . The annular manifold  172  may be configured to receive a relatively warmer of the two flows. A plurality of conduits  150  may be in fluidic communication with the annular manifold  172 . A plurality of outlets  154  may be located on respective ends of each the respective plurality of conduits  150  to mix the relatively warmer flow with the other of the two flows. The fuel filter  118  may include a temperature sensitive valve  170  configured to regulate flow into the manifold  172  from the recirculation line  120 . 
     The container  158  may be substantially cylindrical and may have a central axis  186 . The fuel filter  118  may include a substantially cylindrical insert  174  located within the container  158 . The insert  174  may include a substantially cylindrical body configured to at least partially support the filter medium  152  in an annular shape. One of the conduits may be a first inlet conduit  160  coupled to a relatively cooler flow. The first inlet conduit  160  may be a tube that may be coaxial with the central axis  186 . Another of the conduits  150  may be a plurality of conduits  150  coupled to a relatively warmer flow. The plurality of conduits  150  may be disposed in an annular chamber  188  radially outside the first inlet conduit  160 . The plurality of conduits  150  may be arranged in, for example, a circular pattern  190  ( FIGS. 3 &amp; 4 ). 
       FIG. 7  is a top view of the insert  174  as see from direction indicated with section line  7 - 7  in  FIG. 2 . The fuel filter  118  may include an annular shaped manifold  172  formed in a top portion of the insert  174 . The manifold  172  may include an annular floor  192  and a circumferential wall  194  intersecting a periphery of the floor  192 . A plurality of semicircular slots  196  may be formed into the circumferential wall  194 . A respective plurality of cooperatively disposed holes  198  may be in the floor, and may provide fluidic access to each respective plurality of conduits  150 . 
     The fuel filter  118  may include an outlet formed as an annular outlet flow channel  178  concentric with and radially outside of the first inlet conduit  160 . The filter medium  152  may be an annular filter medium  152  concentric with and radially outside of the annular outlet flow channel  178 . 
       FIG. 8  is a section view illustrating another example fuel filter  118  in accordance with the present disclosure. The fuel filter  118  may be used in the system  100  illustrated in  FIG. 1 . The fuel filter  118  may include a return fuel conduit  150  traversing a filter medium  152 . The conduit may include an inlet  153  in fluidic communication with the fuel recirculation passage  120  via, for example the return fuel line  136 . The fuel filter  118  may include an outlet  178  downstream from the filter medium  152 . The fuel filter  118  may include a substantially rectilinear container  158  disposed to contain a substantially rectilinear filter medium  152 . 
     Referring again to  FIG. 1  wherein a system  100  for an internal combustion engine  10  is illustrated. The fuel filter  118  illustrated in  FIG. 2 , or the fuel filter  118  illustrated in  FIG. 8 , or one or more similarly configured filters may be included with system  100  in accordance with various embodiments. The system  100  may include a first fuel transport line  115  for transporting fuel from a fuel tank  114 . A second fuel transport line  120  may be included for transporting fuel returned from one or more engine components. The system  100  may also include a fuel filter  118 . The fuel filter  118  may include a container  158  having a first end  180  and a second end  176 . A filter medium  152  may be located inside the container  158 . A mixing volume  200  may be located within and near the second end  176  of the container  158  located upstream from the filter medium  152 . A first conduit  160  may be coupled to the first fuel transport line  115  near the first end  180  of the container  158 , and may have a first outlet port  162  open to the mixing volume  200 . A second conduit  150  may be coupled to the second fuel transport line  120  near the first end of the container  158  and having a second outlet port  154  open to the mixing volume  200 , shown in rough approximation as a dashed line shape. 
     The system  100  may include a temperature sensitive valve  170  configured to control a flow of fuel from the second fuel transport line  120  to the second conduit  150 . The second conduit  150  may be six individual conduits  150  each fluidically coupled with a manifold  172  located within and adjacent to the first end  180  of the container  158 . The six individual conduits  150  may be substantially equally spaced along a circumferential line  190  concentric with a central axis  186  of the container  158  ( FIG. 3 ). The temperature sensitive valve  170  may be configured to control a flow of fuel from the second fuel transport line  120  into the manifold  172 . 
     The system  100  may also include an outlet conduit  178  configured to receive a filtrate from a downstream side of the filter medium  152  formed as an annular flow channel radially inside the filter medium  152 , and radially outside the first conduit  160 . 
     The first end  180  of the container  158  may be a top of the container  158 . The second end  176  of the container  158  may be a bottom of the container  158 . The fuel filter  118  may include a mounting configuration  202  for attaching the container  158  to an inside location of an engine compartment of a vehicle. 
     The fuel filter  118  may include a water reservoir  204  which may be configured to collect water from the fuel that passes through the filter  118 . The water reservoir  204  may include a valve  206  wherein the collected water may be let out from the filter  118 . In some cases the fuel filter  118  may be a box filter. In some cases the fuel filter  118  may be substantially cylindrically shaped. 
     While the depicted example shows a single fuel filter, in alternate embodiments two or more filters may be included. Each filter may receive return fuel from respective recirculation branch passages. In one example, flow through each passage may be regulated by respective thermal recirculation valves. A pressure of fuel at the filter may be communicated to the engine controller  12  by a filter pressure sensor/switch (not shown) positioned at the outlet of the filter. 
     The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, functions, or operations may be repeatedly performed depending on the particular strategy being used. Further, the described operations, functions, and/or acts may graphically represent code to be programmed into computer readable storage medium in the control system 
     Further still, it should be understood that the systems and methods described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are contemplated. Accordingly, the present disclosure includes all novel and non-obvious combinations of the various systems and methods disclosed herein, as well as any and all equivalents thereof.