Patent Publication Number: US-2010117842-A1

Title: Contaminant Detection Unit

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to Provisional Application Ser. No. 61/114,248, filed Nov. 13, 2008, entitled Water-Detecting Unit with Self-Test Feature, to which priority is claimed, and the disclosure of which is specifically incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to fuel systems and more particularly to providing apparatuses and methods for detecting and removing contaminants in a fuel system of an internal combustion engine. 
     BACKGROUND ART 
     The fuel for use in internal combustion engines and heating systems is usually filtered before being fed to the engine or heating system. Filters are necessary because the presence of contaminants, such as water, in fuel systems has been found to be particularly disadvantageous for running efficiency of the machine that is using the fuel. For instance, as in the case with diesel or gasoline engines in boats or land vehicles, the presence of water in the fuel may cause corrosion of the fuel injector system with consequent reduction of the efficiency thereof and eventual complete breakdown thereof. Additionally, water in fuel systems may present a dangerous situation when power from an engine is necessary and water in the fuel results in the inability to deliver power at a crucial point in the operation of the engine. 
     In the past, various types of conventional fuel filters have been used in order to separate and/or remove water from the fuel prior to feeding the engine. These conventional fuel filters typically include a casing made of glass or steel that is mounted underneath a bracket having a fuel inlet and a fuel outlet and a filter element that is accommodated within the casing. The fuel introduced from the fuel inlet flows down a central passageway and enters the casing through a lower opening. The fuel changes flow direction to ascend in the casing and is filtered by the filter element and sent to the engine through the fuel outlet. In these conventional fuel filters, a major part of the water content included in the fuel may fall by gravity when the fuel flows from the opening. When the fuel is reversed in direction to flow upwardly, the remainder of the water content may attach to the surface of the filter element and accumulates to form droplets, which fall and gather in the bottom of the casing. A very small amount of water may pass through the filter element but such a small amount of water is very easily fully burned in the engine and typically does not affect engine efficiency. The water gathering in the bottom part of the casing may be removed at a suitable maintenance interval. 
     Drawbacks have been found in such conventional fuel filters. For instance, since a large amount of water may attach to the surface of the filter element and accumulate thereon when the filter is in use, the surface of the filter element applied with water gathering treatment or water repellant treatment is gradually attacked by the water over a period of time so that the life of the filter element is shortened. Furthermore, as a recent requirement especially related to exhaust gas purification, it is necessary to remove the water in the fuel to substantially zero in order to accurately maintain the measuring of the fuel amount at the fuel injection valve. From this requirement, it is necessary to separate the water content in the fuel as completely as possible before reaching the filter element. 
     An additional disadvantage to conventional fuel filters has been realized in regards to the water content accumulated in the bottom part of the casing of the fuel filter that has had to be manually removed at certain regular intervals. It has been found that if the water removing process is forgotten, the water level may reach the lower surface of the filter element wherein not only does the filter efficiency deteriorate but a large amount of water may be sent to the engine together with the fuel. This has an especially detrimental effect when the filter element is old and the filtering function has deteriorated wherein the water sent to the engine may cause rust to be introduced into the fuel injection system or may lead to other major efficiency decreases in engine production. 
     Due to the drawbacks of conventional fuel filtering systems, various apparatuses have been designed to attempt to resolve those negative characteristics by alerting the user of the presence of water and/or automatically draining collected water from the fuel system. 
     U.S. Pat. No. 4,276,161 to Matsui et al. discloses a fuel filter with a water level detector. A sensor responds to water level in the casing of the filter so that if the water level in the casing reaches a predetermined level, a low resistance condition between the electrode in the casing is detected by a water level detecting circuit. U.S. Pat. No. 4,562,431 to Jahnke et al. discloses a sensor system which is passive and which can only be used with one type of fuel system. 
     In a more recent development as described in U.S. Pat. No. 7,368,060 to Fachidis, the inventor in the present application, apparatuses and methods are disclosed for detecting contaminants in a fuel system. The apparatus described therein includes a programmable low voltage variable contaminant detection sensor formed integrally within an upper unit of a fuel filter unit, with probes extending into a lower unit of the fuel filter for sensing contaminant levels within a contaminant collection zone. Due to the fact that the sensor unit is programmable, the unit can be used in a variety of different types of fuel systems and overcomes some of the aforementioned disadvantages of the prior art. 
     In accordance with the invention described herein, there is provided an improved apparatus and method over that described in the references above, which are incorporated herein by reference. The present invention maintains the flexibility to be used in different fuel systems due to programmability, but also allows replacement of the sensor module thereof without requiring replacement of the entire fuel filter unit. The improved apparatus and method also allows for more usability by allowing the sensor module to be used with varying off-the-shelf contaminant filters. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect, the invention is an apparatus for detecting contaminants, e.g., water, in a fuel system. A fuel filter unit includes an upper unit having an upper section with a fuel inlet port, a fuel outlet port, and a closeable vent port. The upper unit includes a lower section with an open interior space bounded by walls thereof for receiving a fuel filter which is housed therein. The upper unit also includes an opening at the bottom thereof. 
     A lower unit is provided which is releasably mounted to the upper unit at the opening at the bottom, for sealing the upper unit. The lower unit has a programmable contaminant detection sensor which includes at least one detection probe extending upwardly into a fuel compartment region, for generation of a signal upon contact with a predetermined level of contaminant. A control board is housed within the lower unit and connected to at least one detection probe, and both make up the sensor. The control board includes a microprocessor and is capable of varying the predetermined level. An indicator is provided for generating an alarm condition in response to receiving the signal. 
     By having the sensor housed in the lower unit which is releasably mounted to the upper unit, it becomes possible to easily replace the sensor unit in the event of failure. Further, as noted, the sensor is programmable having a board with a microprocessor therein, and housed within the lower unit. In addition, due to the relative density differences between fuel and water, water tends to collect towards the bottom and is more easily detectable by the sensor resulting in an earlier warning, depending on the programming set for the unit, for fuel being fed to an internal combustion engine. 
     In an alternative aspect, there is provided a method of detecting contaminant in a fuel system of an internal combustion engine. The aforementioned contaminant detection apparatus is provided. The apparatus is then placed between the fuel source and the internal combustion engine. A microprocessor on the board is programmed with a predetermined level of contaminant selected for generating an alarm signal. Fuel is caused to enter the contaminant detection apparatus from the fuel source and the fuel is monitored so that an alarm signal is generated when the predetermined level of contaminant is reached. Preferably, the indicator for generating an alarm signal is one of a visual and audible signal so that two ways of perceiving the signal are provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the overall fuel system of an engine incorporating the contaminant detection apparatus provided in accordance with the subject matter disclosed herein. 
         FIG. 2  is a perspective partially exploded view of an embodiment of a contaminant detection apparatus provided in accordance with the subject matter disclosed herein. 
         FIG. 3  is a partial cross-section view of the lower unit of the contaminant detection apparatus illustrated in  FIG. 2 . 
         FIG. 4  illustrates a standard filter unit in accordance with the prior art having a releasable top and lower bowl. 
         FIG. 5  is a partial view of an alternative embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIG. 1 , a fuel system incorporating the preferred embodiment of the contaminant detection apparatus of the present invention is shown. The fuel system includes a fuel source F that supplies fuel to engine E for the powering of an attached machine, wherein the fuel supplied by fuel source F may consist of gasoline, diesel or any other type of petroleum product. It is understood that engine E may comprise an internal combustion engine for powering a vehicle such as a marine craft or land vehicle, may comprise a burner system for heating applications, or may comprise any other application that utilizes petroleum products. A preferred embodiment of an apparatus for detecting contaminant in the fuel being fed from fuel source F is shown generally as  10 , and is positioned in operative connection between fuel source F and engine E. The placement of contaminant detection apparatus  10  allows for detection and/or removal of contaminant in the fuel prior to the contaminated fuel reaching engine E. With such placement, the contaminant destruction of other fuel system parts of engine E, such as the injection system and the like, is minimized. While the most often cited contaminant in fuel systems is water, it is understood that the present subject matter may be directed to detecting any other contaminants found in fuels. 
     With reference to  FIG. 1 , and with further reference to  FIGS. 2 and 3 , contaminant detection apparatus  10  can include a fuel filter unit  13 . The fuel filter unit  13  includes an upper unit  35  and a lower unit  43  and houses a fuel filter element (not shown) of any type known to those of skill in the art. 
     Upper unit  35  is preferably constructed of a metal material and includes an upper portion  37 , including a fuel inlet port  45  for receiving of fuel from fuel source F and a fuel outlet port  47  wherein the fuel exits the fuel filter unit  13  and is fed to engine E. Upper portion  37  may also include a closeable vent port (not shown) for releasing vacuum within fuel filter unit  13  during draining of contaminant from the unit. The upper portion  37  which includes the inlet  45  and outlet  47 , may be made detachable to allow replacement of a filter within the upper unit  35 . The upper unit  35  also includes a lower portion  39  with an opening  41  for receiving a lower unit  43  therein. 
     As shown in  FIGS. 2 and 3 , the lower unit  43  includes one or more detection probes  45  that extend into the upper unit  35  through lower section  39  for sensing contaminant levels within a contaminant collection zone. 
     The contaminant detection sensor  45  measures the resistance variation in the fuel caused by the presence of water or other contaminants and is capable of determining when the resistance moves below a certain predetermined threshold level. The sensor probes  45  are continuously under voltage, with the voltage typically being a low-voltage such as 5 volts that will not cause sparking within the fuel source. The sensor probe  45  typically includes a control board  71  which may be housed in an isolated compartment  73  shown in  FIG. 3 , and incorporating a software program detection algorithm which is capable of varying levels of programmability. As such, the same contaminant detection probe  45  which is housed above an upper cap  75  of the isolated compartment  73  within which the control board  71  is housed (making up a sensor), may be used for different size engines where the capacity of the fuel filter unit can differ significantly. 
     The contaminant detection probe  45  is constantly monitoring fuel flowing through the fuel filter unit  13 , and is adapted to generate a signal, such as an alarm signal, upon detection of a predetermined level of contaminant such as water in the contaminant collection zone. 
     As shown in  FIG. 1 , the overall contaminant detection apparatus  10  may further include at least one indicator  23 . The indicator  23  and other electronic components are powered by a battery B, such as a 12 volt or 24 volt battery power source. The indicator  23  and other electrical components are connected to battery B via cables such as cables  15  and  21  with connectors  17  and  19 , and connectors  25  and  27  to red and black battery terminals  31  and  33  through a fuse  29 . In actual implementation, the indicator  23  may be a visual or audible indicator, and may be placed on or near the fuel filter unit, or may be placed close to the vehicle user, such as at a helm position on marine vehicle. 
     The incorporation of the indicators  23  allows the user to not have to constantly monitor the fuel filter unit itself, and alerts the user when contaminant in the fuel has reached a threshold level and requires draining. 
     The sensor  45  and control board  71  may also include a self-test feature which serves to function to inform the user that the system and its audible or visual indicators are operational, and may derive from software designed and installed on the control board  71  having a microprocessor thereon. The self-test may operate upon initial start up of the engine to show that the sensor system and indicator  23  is working. 
     As may be appreciated, upon detection of water or other contaminants in the system, the visual indicator or audible indicator  23  will serve to alarm the user. The vent for the filter unit  13  (not shown) can be open and drain plug  51  can be removed from opening  49  to allow water to drain out. 
     As an example of use of the invention, the detection apparatus  10  previously described may be placed between a fuel source and the engine. The user then programs the contaminant detection sensor probe  45  and control board  71  with a predetermined level of contaminant desired for generation of an alarm signal. For example, the sensor may be programmed to generate an alarm signal when the concentration of water reaches 20%. The predetermined level may vary with engine size or type as will be readily apparent to those of ordinary skill in the art. 
     Once the contaminant threshold has been programmed, fuel may be caused to enter the fuel filter  13 , typically by starting the engine. As fuel flows through the system, the detection probe  45  monitors the accumulation of contaminant in the contaminant collection zone or the lower unit  43 . It should be noted that since the probe  45  is located towards the bottom of the filter unit  13 , because of the relative difference in density between fuel and water, that it is likely that water will be found in a lower region in increasing concentration towards the lower unit  43  thus providing for earlier detection. 
     Once the predetermined level is reached, the sensor probe  45  and control board  71  generate a signal which is then received by the indicators to alert the user. 
       FIG. 4  illustrates an alternative arrangement  101  of a conventional fuel filter. A top section  103  includes a fuel inlet  105 , a fuel outlet  107  and a vent (not shown). The top section is designed to attach to a self contained filter unit  109 , encased, for example, by a metal shell. The attachment may be achieved by threaded engagement or other like engagement. At the bottom is a containment collection bowl  111 , with a discharge opening  113  for containment when a plug  115  thereof is removed. 
     In accordance with an alternative embodiment of the invention, the prior art device of  FIG. 4  may be modified as shown in  FIG. 5 . More specifically, the self contained filter unit  109  has threads  117  for typically engaging with O-ring  119  interposed, a sensor containing collector bowl  121  containing the control board and contaminant collection zone (both not shown) therein, as described hereinabove. Detection probes  145  extend up and are integral with the sensor containing collector bowl  121 . A discharge opening  123  with plug  125  allows discharge of contaminant. An indicator light  127  may be affixed to the system and powered through cable  135  and connector  137  by a battery. 
     The various components of the invention may be made of standard materials such as metals, plastics, composites or other like materials. 
     It will be understood that various details of the present invention may be changed without departing from the scope of the present invention. Various aspects of each embodiment described herein may be interchanged with various aspects of other embodiments. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation.