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.
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.
The following description relates to systems and methods for diesel fuel conditioning.
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 (Pfuel
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'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.
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.
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
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 (
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.
Referring again to
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 (
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.