Abstract:
A switchable fuel filter assembly with alternate fuel paths which carry fuel, respectively, through alternate fuel filters depending on the position of a valve member.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to motor vehicle accessories and fuel systems. 
   2. Background Information 
   Diesel engine vehicles are more prone to disablement from fuel filter stoppage than gasoline vehicles. This is true, in part, because diesel fuel is less “pure” than more gasoline, and impurities will often accumulate and clog a fuel filter. 
   Presently, a clogged fuel filter will disable a vehicle until or unless the filter is removed and replaced. This is certainly an inconvenience, but is more than that. Under certain circumstances, safety become far more a prominent issue than convenience, when, for example, a fuel filter reaches a level of occlusion during use that the engine loses most or all of this power, and this occurs on a busy highway or freeway. Clearly, if this occurs with a tractor trailer under such circumstances, the safety issues because of the traffic entanglements are numerous. 
   There is virtually nothing in the practical realm that anyone can do to prevent fuel filters from clogging. In so doing, fuel filters are, in essence, simply doing what they are designed to do—catch contaminants before they reach fuel injectors, which are much more expensive to service or replace. 
   Even if one were to change fuel filters periodically in anticipation of clogging and in view of a more or less “normal” rate of occlusion, variations in fuel contamination would inevitably fail, from time to time, to “catch” a fuel filter in time to prevent all power losses. 
   What is needed, therefore, is a device or system which accommodates the inevitability of fuel filter stoppage by providing immediate alternative fuel pathways once a stoppage is noted. It is an object of the present invention to obviate the inconvenience and safety hazards which attend diesel fuel filter stoppage, and in so doing provide just such a device or system. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top plan, cross sectional view of a filter switching assembly of the present invention, with the switching means positioned for directing fuel in the first of two fuel pathways. 
       FIG. 2  is a top plan, cross sectional view of a filter switching assembly of the present invention, with the switching means positioned for directing fuel in the second of two fuel pathways. 
       FIG. 3  is a side elevational view of a preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 1 and 2 , the switchable diesel fuel filter assembly of the present invention is identified generally by the reference number  5 . Filter assembly  5  includes a fuel ingress port  6  and a fuel egress port  7 . A valve assembly  8  (shown only in concept form, as such valve may take many forms in actual reduction to practice) is switchable between a first position ( FIG. 1 ) where fuel is directed through conduit, or fuel path  12 , in which fuel filter  10  is in-line, or a second position ( FIG. 2 ) where fuel is directed through conduit, or fuel path  11 , in which fuel filter  9  is in-line. 
   Clearly, fuel egress port  7  delivers fuel to the down stream fuel system of a vehicle in which the present filter assembly  5  is installed. Accordingly, if one operates with valve means  8  in the first position, and filter  10  becomes clogged, moving valve means to the second position will simply re-direct fuel to pass through filter  9  which, if one has properly services the filter assembly  5 , will be a “fresh filter.” 
   As shown in  FIG. 3 , the filter assembly  5  includes a filter head  13  having a lower surface and extending horizontally between first and second ends, the first end having the fuel ingress port  6  and the second end having the fuel egress port  7 . As shown in  FIG. 1 , a fuel ingress passage  14  extends through the filter head  13  from the fuel ingress port  6  to a fuel ingress junction  15  (see FIG.  1 ). A first ingress branch passage  16  extends through the filter head from the fuel ingress junction  15  to a first filter inlet connection  17  on the lower surface of the filter head. A second fuel ingress passage  18  extends through the filter head from the fuel ingress junction  15  to a second filter inlet connection  19  on the lower surface of the filter head. A fuel egress passage  20  extends through the filter head from the fuel egress port  7  to a fuel egress junction  21 . A first fuel egress passage  22  extends from the fuel egress junction  20  to a first filter outlet connection  23  located on the bottom surface of the filter head proximate the first filter intake connection  17 . A second fuel egress passage  24  extends from the fuel egress junction  20  to a second fuel filter outlet connection  25  located on the bottom surface of the filter head proximate the second filter intake connection. As shown in  FIG. 1 , the fuel ingress port  6 , the fuel egress port  7 , the first filter inlet connection  17 , and the second filter inlet connection  19  include central axes that are parallel to and coincident with a single vertical plane. The first filter inlet connection  17  is positioned closer to the fuel ingress port  6  than the second filter inlet connection  19 , and the second filter inlet connection  19  is positioned closer to the fuel egress port  7  than the first filter inlet connection  17 . The fuel ingress junction  15  is positioned horizontally between the fuel ingress port  6  and the first filter inlet connection  17 , and the fuel egress junction  21  is positioned horizontally between the fuel egress port  7  and the second filter inlet connection  19 . A first fuel filter  9  is provided including a centrally located inlet connection connected to the first filter inlet connector  17  and a filter outlet connected to the first filter outlet connection  23 . A second fuel filter  10  is provided including a centrally located inlet connected to the second filter inlet connection  19  and a filter outlet connected to the second filter outlet connection  25 . Valve means  8  is located in the fuel ingress junction  15  and is positionable in first and second valve means positions, respectively for selectively directing fuel entering the fuel ingress port through either the first fuel ingress passage  16  to the first fuel filter  9  or through the second fuel ingress  18  passage to the second fuel filter  10 . 
   Filter assembly  5  would be useful and of considerable convenience, even if valve means required actuation directly at filter assembly  5  (as if a lever or know allowed actuation). However, such would not completely address the safety concerns of a power loss due to fuel filter stoppage while driving. Therefore, any preferred embodiment of the present invention will include remote valve actuation means (not shown in the drawings). 
   Remote valve actuation means may come in any of several forms. An electric, solenoid type of actuator, which may be operated from the cab of a truck, for example, may be one option of remotely operating the switching function of fuel filter assembly  5 , whereby, upon the notice of a power loss which is apparently the result of clogged fuel filter, the driver can stitch to the “good” filter. Even a cable-based, purely mechanical actuator would suffice, whereby a push-pull, or even dial type switch accessible to the driver could move the external actuator portion of valve means  8  between its two positions. These and other actuation options are well within the skills of persons reasonable skilled in designing and manufacturing vehicle systems and accessories, and need not be further elaborated for enabling disclosure purposes. 
   Referring to  FIG. 3 , in the preferred embodiment of the present invention, each of fuel filters  9  and  10  reside in a screw-on filter housing for each removal and replacement. 
   Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon the reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.