Abstract:
A apparatus separates out and removes water present in liquid fuels. The fuel supplies an internal combustion engine by a fuel delivery pump ( 12 ). Water is separated out at a filter ( 5 ) having a collecting space ( 27 ) for collecting separated water and connected upstream of the suction side ( 11 ) of the fuel delivery pump ( 12 ). The pump suction action counteracts outflow of water from the collecting space ( 27 ). Depending on the amount of water collected, the pump suction action is negated, and an outlet valve at an outflow orifice ( 37 ) of the collecting space ( 27 ) is opened by a discharge ( 43, 53 ) producing a pressure gradient enabling the discharge of water from the collecting space ( 27 ) over a discharge period when the fuel delivery pump ( 12 ) is operating.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a division of U.S. patent application Ser. No. 12/225,917, the entire subject matter of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a process for separating out and removing water present in liquid fuels, especially water from diesel oil. The fuel is conveyed in a line system to supply an internal combustion engine by a fuel delivery pump. Water is separated out at a filter arrangement having a collecting space for collecting the separated water and is connected upstream from the suction side of the fuel delivery pump so that its sucking action counteracts an outflow of water from the collecting space. Depending on the collection of a given amount of water at the filter arrangement, the sucking or suction action of the delivery pump is negated, and an outlet valve located at an outflow orifice of the collecting space for removing water is opened. Moreover, the invention relates to an apparatus for executing this process. 
       BACKGROUND OF THE INVENTION 
       [0003]    The drainage of water, with these measures being carried out, is conventional and is especially essential when heavy diesel machinery is operated under severe use conditions. For example, when using heavy machinery with heavy diesel engines in less highly developed countries, obtaining fuel of Central European quality is difficult. In fact, in countries with difficult climatic conditions and poor infrastructure, users must expect that the available fuel will have significant impurities, in particular a high water content. Construction and agricultural machinery is often fueled from barrels stored and transported more often with little or no covering at all, so that they are exposed unprotected to the elements such as rain. 
         [0004]    According to experience, a maximum water content in diesel oil of up to 10% can be expected. Vandalism and corrupt handling can be responsible for these high water contents. 
         [0005]    When highly contaminated diesel oil is used, for example, in the tank of a high-performance common rail diesel engine with consumption of approximately 400 l/day, the amount of water to be drained is about 40 l/day. For commercial filters/water separators the capacity in the water collecting tank is at most 0.5 l. In view of this prior art, the operator, to carry out the conventional drainage process, must shut off the engine roughly 80 times during the workday to negate the suction force of the fuel delivery pump counteracting the outflow of water from the filter arrangement. The operator must also open the outflow orifice of the water collecting space to allow the collected water to flow out. If the operator does not observe the requirements, after some time water bleeds through the filter arrangement into the injection system damage it, resulting in very high maintenance costs and a correspondingly long downtime of the pertinent device. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the invention is to provide a process meeting the requirements arising in operation of internal combustion engines, in particular heavy diesel engines, to an especially satisfactory degree. 
         [0007]    Proceeding from conventional processes, this object is basically achieved according to the invention by negating the sucking action counteracting the outflow of water by a discharge. The discharge produces a pressure gradient enabling outflow of water at the outflow orifice of the collecting space over a discharge interval and during current operation of the fuel delivery pump. 
         [0008]    The discharge process is initiated by a pressure difference produced between the inside of the collecting space and the outside causing discharge of water via the outflow orifice. The process according to the invention then enables discharge processes to be carried out while the engine is running Therefore, discharge processes can be carried out in comparatively rapid succession and over comparatively short discharge intervals, without disrupting operation and during operation of the injection system, with the fuel delivery pump continuing to run. The storage volume of the injection system can be discharged without needing to shut down the engine. 
         [0009]    The process according to the invention enables the option of complete automation. In an especially advantageous manner, a water sensor unit detecting collection of a given amount of water and its outflow produces a signal to activate the discharge means and to automatically initiate a discharge process. The danger that the water can bleed through due to operator error is therefore prevented. 
         [0010]    In especially advantageous embodiments, the discharge has control electronics processing the signal of the water sensor unit to determine the discharge intervals and to produce control signals for activation of the discharge and control of the outlet valve during the determined discharge intervals. 
         [0011]    The pressure gradient enabling outflow of water at the outflow orifice can be produced in different ways. For example, the discharge can have a discharge pump with a suction side connected to the outflow orifice of the collecting space and producing a pressure gradient when the discharge is activated. This embodiment constitutes a comparatively simple procedure in which sucking of water out of the collecting space takes place as necessary while the system remains in operation, without the need for interventions or changes on the actual line system. 
         [0012]    Alternatively, the discharge has a hydropneumatic accumulator with an oil side charged with fuel by the fuel delivery pump, and a valve actuatable by the control electronics. By the accumulator in the filter arrangement over a discharge interval, a pressure is built up producing the pressure gradient necessary for outflow of water at the outflow orifice. In this form of the process, the advantage is that an additional discharge pump is not necessary. 
         [0013]    Advantageously, depending on the signal of a temperature sensor detecting the temperature of the separated water, the control electronics can produce a heating control signal for a heating element. The heating element is designed to protect against freezing. In this way operating reliability is ensured even in winter operation or in cold climate zones. 
         [0014]    The subject matter of the invention is also an apparatus for carrying out the process according to the invention. 
         [0015]    Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Referring to the drawings which form a part of this disclosure: 
           [0017]      FIG. 1  shows a simplified operating or schematic diagram of a system according to a first exemplary embodiment of the invention; 
           [0018]      FIG. 2  is a simplified operation or schematic diagram of a system according to a second exemplary embodiment of the invention; 
           [0019]      FIG. 3  is a schematic side elevational view partially in section of an apparatus according to the system of  FIG. 1 ; and 
           [0020]      FIG. 4  is a schematic front elevational view partially in section of the apparatus of  FIG. 3 , turned 90 relative to  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    To illustrate a first exemplary embodiment of the invention,  FIG. 1  shows a schematic block diagram of the fuel supply system of a diesel engine with common rail injection. Emerging from a fuel tank  1  the line system has a tank line  3  leading to the inlet  6  of a prefilter  5 . The prefilter  5  with a fineness of approximately 30 μ has a water separator  7 . The outlet  8  of the prefilter  5  is connected to a suction line  9  leading to the suction side  11  of a fuel delivery pump  12 . Its pressure line  13  is connected to the inlet  15  of a fine filter  17  having a fineness of approximately 2-5 μ. The outlet  19  of the fine filter  17  is connected to a common rail injection system  21  with its injection nozzles  23 . Nozzles  23  are connected by a recirculation line  25  leading back to the tank  1 . 
         [0022]    Water separated from the fuel flowing through the prefilter  5  by the water separator  7  collects in the bottom region of the prefilter  5  and in the collecting space  27  adjoining the underside of prefilter  5 . Details of the fluid connection and the positional relationship between the water separator  7  and the collecting space  27  are explained below using  FIGS. 3 and 4 . A water sensor unit  29  detects the height of the level of the collected water in the collecting space  27  and is connected by and transmits signals to the control electronics  31 . The control electronics  31  processes not only the signals of the water sensor unit  29 , but also those of a temperature sensor  33  to activate a heating element  35  in the collecting space  27  when a freezing temperature has been ascertained. 
         [0023]    The collecting space  27  is connected via its outflow orifice  37  to the suction side  41  of the discharge pump  43 . The discharge pump pressure side leads to a capture tank  45  for the discharged water. The pump  43  can be a pump version which blocks against backflow. Alternatively, a nonreturn valve  39  can be the outlet valve between the outflow orifice  37  and the pump  43 . 
         [0024]    When the water sensor unit  29  detects a level in the collecting tank  27  corresponding to a given amount of collected water and signals this condition to the control electronics  31 , a discharge process is initiated by the control electronics  31  starting the motor of the pump  43  via the supply line  47 . The intake capacity of the pump  43  is chosen such that its sucking or suction action exceeds the sucking or suction action of the fuel delivery pump  12  so that at the outflow orifice  37  of the collecting space a pressure gradient is produced such that the collected water flows out, i.e., is sucked out by the pump  43 . The duration of the discharge interval with the pump  43  remaining on can be determined depending on the signal of the sensor unit  29 . Operation of the pump  43  is adjusted by a certain amount when the water level drops, or can be controlled depending on time, by the pump  43  operating over a fixed time interval for each discharge process. In each instance the fuel delivery pump  12  remains in operation during the discharge processes so that the engine need not be shut down. 
         [0025]    The example shown in  FIG. 2  differs from the example shown in  FIG. 1  by the use of a discharge in the form of a pressure control which replaces the discharge pump  43  from  FIG. 1 . Components which correspond to the example from  FIG. 1  are designated in  FIG. 2  with the same reference numbers as in  FIG. 1 . As is apparent from  FIG. 2 , the pressure line  13  of the fuel delivery pump  12  leads not only to the inlet  15  of the fine filter  17 , but also to the oil side  51  of a diaphragm accumulator  53  charged with fuel by the operating fuel delivery pump  12 . To initiate a discharge process taking place as in the first embodiment by delivering the signal from the sensor unit  29  and by the resulting activity of the control electronics  31 , a 3/2-way valve  55  connected upstream from the inlet  6  of the prefilter  5  in the tank line  3  and a 2/2-way valve  57  connected downstream from the outlet  8  of the prefilter  5  are actuated. During the discharge interval, the valve  57  is closed and the valve  55  is actuated such that the tank line  3  is blocked and the oil space  51  of the diaphragm accumulator  53  is connected to the inlet  6  of the prefilter  5  by a branch line  59  and the 3/2-way valve  55 . At the outflow orifice  37  of the collecting space  27  the pressure gradient presses the collected water out of the collecting space  27  to travel to the capture tank  45 . The pressure gradient is formed by the pressurized volume of oil supplied to the prefilter  5  by the diaphragm accumulator  53 . In the example shown in  FIG. 2 , the outlet  8  of the prefilter  5  during the discharge interval can be blocked by the valve  57 . When the diaphragm accumulator  53  is charged with enough pressure and a sufficiently large volume of pressurized oil flowing via the valve  55  into the prefilter  5  is available in the oil space  51  so that a sufficient pressure rise is formed in the prefilter  5  during the discharge interval, the 2/2-way valve can be omitted. As in the first described embodiment, during the discharge interval the fuel delivery pump  12  can continue to operate, i.e., the engine need not be shut down. When the discharge interval is ended, the valve  55 , optionally the valve  57 , is controlled again such that flow takes place through the tank line  3  and the suction line  9 . The branch line  59  is blocked again, and the diaphragm accumulator  53  is again charged by the pressure line  13 . 
         [0026]      FIGS. 3 and 4  show one example of the apparatus according to the invention for executing the process. The apparatus is made as a retrofit system attachable to the underside  61  of the prefilter  5  at a later time. Its filter casing is made in the form of a spin-on filter. 
         [0027]    As  FIGS. 3 and 4  show, the central region of the bottom on the underside  61  has a water outlet  63  with an internal thread. A hollow screw  65  is screwed into that internal thread. Internal holes  67  of screw  65  form a fluid connection between the bottom region on the underside  61  of the filter casing and a central depression  69  located on the upper end of a body  71 . Body  71  is tightened by the hollow screw  65  on the underside  61  of the filter casing. A gasket  73  forms an edge-side seal. 
         [0028]    The depression  69  forms the water collecting space  27  for the water separated out by the water separator  7  of the prefilter  5 . The water level in the collecting space  27  is detected by the water sensor unit  29 . Underneath the depression  69  forming the collecting space  27 , cavities are in the body  71  for holding the control electronics  31  (see  FIG. 3 ), the discharge pump  43  (see  FIG. 4 ) and other components which are not shown. 
         [0029]    While  FIGS. 3 and 4  show the apparatus according to the invention in an exemplary embodiment made as a retrofit system suited for installation into existing systems at a later time. The invention is also especially suitable as original equipment for the pertinent systems. 
         [0030]    In particular, the apparatus according to the invention together with the prefilter  5  having a separator  7  and other system components, such as the pump  43 , sensor unit  29 , electronics  31 , heating element and the like, can be combined in a standard housing. 
         [0031]    While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.