Abstract:
A fuel system for an LPI engine according to an exemplary embodiment of the present invention may include a reservoir disposed in a fuel tank, a recovery pipe inserted in the reservoir, and a fuel pump disposed in the reservoir and supplying LPI fuel, wherein liquefied fuel mixed with gaseous fuel recovered through the recovery pipe is separated in the reservoir and the liquefied fuel is pumped again by the fuel pump.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2007-0131600 filed in the Korean Intellectual Property Office on Dec. 14, 2007, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to a fuel system for a liquefied petroleum injection (LPI) engine, and more particularly to a fuel system for an LPI engine integrally provided with a fuel pump such that the fuel system has less components and manufacturing cost of the fuel system is reduced. 
         [0004]    (b) Description of the Related Art 
         [0005]    An LPI engine has high power and low emission of pollutants, and alleviates problems of conventional liquefied petroleum gas (LPG) engines such as environmental pollution, low power, and low quality. 
         [0006]    An LPI engine injects high pressure liquefied fuel with an injector. That is, a fuel pump is mounted in a fuel tank and supplies fuel to the injector through a fuel line. 
         [0007]    Power performance of an LPI engine is substantially the same as a gasoline engine, and fuel consumption and acceleration performance of an LPI engine is good. In addition, startability of an LPI engine is remarkably enhanced. 
         [0008]    A supply pipe is mounted between the fuel pump and the injector, and a recovery pipe is mounted between the injector and the fuel tank. Fuel remaining in a combustion process in an engine is recovered to the fuel tank through the recovery pipe. A return valve (check valve) is mounted at the recovery pipe. 
         [0009]    According to a conventional fuel system for an LPI engine, noise may occur at the return valve when mixture of liquefied and gaseous fuel is recovered. 
         [0010]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention has been made in an effort to provide a fuel system for an LPI engine having advantages of reducing noise when liquefied and gaseous fuel is recovered. 
         [0012]    In addition, the present invention has been made in an effort to provide a fuel system for an LPI engine having further advantages that fuel recovered to a fuel tank is easily supplied to an engine. 
         [0013]    A fuel system for an LPI engine according to an exemplary embodiment of the present invention may include: a recovery pipe wherein liquefied fuel mixed with gaseous fuel is recovered therethrough; a reservoir wherein an end portion of the recovery pipe is inserted therein and separates the liquefied fuel from the mixture of the liquefied fuel and the gaseous fuel; a supply pipe wherein an end portion the supply pipe is positioned in the reservoir; and a fuel pump disposed in the reservoir and supplying LPI fuel while the liquefied fuel separated from the mixture of the liquefied fuel and the gaseous fuel is pumped back through the supply pipe by the fuel pump. 
         [0014]    The fuel system may further comprise a cover including a first recovery hole and a supply holes wherein the cover substantially encloses an upper portion of the reservoir and the end portion of the recovery pipe is configured to be connected with the reservoir through the first recovery hole and the end portion of the supply pipe is configured to be connected to the fuel pump through the supply hole. 
         [0015]    The cover of the fuel system may include at least a gas hole on the cover to release gas. 
         [0016]    The first recovery hole of the fuel system may be configured to include a gap between an inner circumference of the first recovery hole and the recovery pipe sufficiently enough to release the gas and/or the supply hole is configured to include a gap between an inner circumference of the supply hole and the supply pipe sufficiently enough to release the gas. 
         [0017]    The fuel system of the present invention as an exemplary embodiment may include a first pathway formed in a longitudinal direction of the reservoir from a lower portion of the reservoir, and the liquefied fuel mixed with the gaseous fuel is moved upwardly through the first pathway. 
         [0018]    The first pathway may be formed by a partition and a portion of the interior surface of the reservoir along the longitudinal direction of the reservoir. 
         [0019]    The fuel system of the present invention as an exemplary embodiment may include a second pathway is connected between the end portion of the recovery pipe and a lower portion of the first pathway, and positioned at the lower portion of the reservoir. 
         [0020]    The end portion of the recovery pipe and one end of the second pathway may be connected by a connector opened toward an tipper direction to receive the end portion of the recovery pipe. 
         [0021]    The fuel system of the present invention as an exemplary embodiment may include a reservoir cup mounted in the reservoir, wherein a lower surface of the reservoir cup is spaced with a predetermined height from the lower portion of the reservoir by a retainer of the reservoir cup and provided with a groove corresponding to the first pathway and a second recovery hole through which the recovery pipe passes. 
         [0022]    The liquefied fuel mixed with the gaseous fuel may be spouted upwardly over the reservoir cup through the first pathway, and thereby the liquefied fuel is separated from the mixture of the liquefied fuel and the gaseous fuel by weight. 
         [0023]    The reservoir cup may further include a rim wherein the rim supports the reservoir cup against the reservoir and prevents the liquefied fuel separated from the mixture from overflowing the lower surface of the reservoir cup. 
         [0024]    The rim of the reservoir cup may be positioned under or the same level of top portion of the first pathway and configured to be positioned substantially at a center of the reservoir cup and at least a mounting bracket having at least an inlet hole is formed at a upper portion of the retainer to mount the fuel pump and collect through the inlet hole the liquefied fuel separated from the mixture. 
         [0025]    As an exemplary embodiment of the present invention, the LPI fuel sucked through a suction hole may be pumped to the supply pipe and a part of the LPI fuel sucked through the suction hole may be merged into the liquefied fuel mixed with the gaseous fuel in the second pathway. 
         [0026]    The above features and advantages of the present invention will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated in and form a part of this specification, and the following Detailed Description of the Invention, which together serve to explain by way of example the principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments thereof illustrated the accompanying drawings which are given hereinbelow by way of illustration only, and thus are not limitative of the present invention, and wherein: 
           [0028]      FIG. 1  is a perspective view of a fuel system for an LPI engine according to an exemplary embodiment of the present invention; 
           [0029]      FIG. 2  is an exploded perspective view of a fuel system of an LPI engine according to an exemplary embodiment of the present invention; 
           [0030]      FIG. 3  is a perspective view of a reservoir cup according to an exemplary embodiment of the present invention; 
           [0031]      FIG. 4  is a perspective view of a reservoir according to an exemplary embodiment of the present invention; and 
           [0032]      FIG. 5  is a cross-sectional view taken along a line I-I of  FIG. 2   
       
    
    
       [0033]    It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations and shapes will be determined in part by the particular intended application and use environment. 
         [0034]    In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 &lt;Description of Reference Numerals Indicating 
               
               
                 Primary Elements in the Drawings&gt; 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 100: fuel system 
                 105: recovery pipe 
               
               
                   
                 110: supply pipe 
                 115: reservoir 
               
               
                   
                 120: cover 
                 130: first recovery hole 
               
               
                   
                 140: supply hole 
                 205: reservoir cup 
               
               
                   
                 210: second recovery hole 
                 215, 215a, 215b: partition 
               
               
                   
                 220: first pathway 
                 225: mounting bracket 
               
               
                   
                 230: lower surface 
                 250: rim 
               
               
                   
                 260: mounting hole 
                 263: retainer 
               
               
                   
                 265: inlet hole 
               
               
                   
                 300: groove 
                 400: connector 
               
               
                   
                 405: second pathway 
                 500: recovered fuel 
               
               
                   
                 505: sucked fuel 
                 520: suction hole 
               
               
                   
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0035]    Hereinafter reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0036]    Hereinafter, referring to the accompanying drawings, a fuel system for an LPI engine according to an exemplary embodiment of the present invention will be described in detail. 
         [0037]      FIG. 1  is a perspective view of a fuel system for an LPI engine according to an exemplary embodiment of the present invention. 
         [0038]    As shown in  FIG. 1 , a fuel system  100  for an LPI engine includes a supply pipe  110 , a recovery pipe  105 , a reservoir  115  and a cover  120 . A first recovery hole  130  and a supply hole  140  is configured to receive supply and recovery pipes  105  and  110  respectively and through the first recovery hole  130 , the recovery pipe  105  is inserted into the reservoir  115  and through the supply hole  140 , the supply pipe  110  is inserted into the reservoir  115 . 
         [0039]    A fuel pump (referring to  FIG. 5 ) is mounted in the reservoir  115 . 
         [0040]    According to the present exemplary embodiment, the fuel pump may be a brush-type motor or a brushless DC motor. 
         [0041]    The brush-type motor has a simple structure and is inexpensive, but has drawbacks such as occurrence of cavitations and low durability. 
         [0042]    The brushless DC motor has a long life, but has a complex structure and is expensive. The fuel pump mounted in the reservoir is well known to a person skilled in the art so a detailed description will be omitted. 
         [0043]      FIG. 2  is an exploded perspective view of a fuel system of an LPI engine according to an exemplary embodiment of the present invention. 
         [0044]    As shown in  FIG. 2 , the fuel system  100  includes the reservoir  115  and a reservoir cup  205 . 
         [0045]    The reservoir cup  205  is mounted in the reservoir  115 . The reservoir cup  205  comprises a rim  250 , a retainer  263 , a second recovery hole  210 , a groove  300  and a lower surface  230 . The retainer  263  comprises one-side opened mounting hole  260  formed at an upper portion of the retainer  263  and positioned substantially at a center portion of the power surface  230  of the reservoir cup  205 . The lower surface  230  of the reservoir cup  205  is spaced from a lower portion of the reservoir  115  with a predetermined height by the retainer  263 . 
         [0046]    The fuel pump (referring to  FIG. 5 ) is mounted in the retainer  263  and receives liquefied fuel separated from a mixture of the liquefied fuel and gaseous fuel as explained later in detail. 
         [0047]    A partition  215  is formed at a portion of an interior surface of the reservoir  115  and complimentarily supported by the groove  300  of the reservoir cup  205 . 
         [0048]    In addition, the second recovery hole  210  is formed at a portion of the lower surface  230  of the reservoir cup  205  and the recovery pipe  105  is configured to be inserted into the second recovery hole  210  of the reservoir cup  205  after the recovery pipe  105  passes through the first recovery hole  130  formed at the cover  120 . Therefore, the mixture of liquefied and gaseous fuel recovered through the recovery pipe  105  is moved to a lower portion of the reservoir  115 . 
         [0049]    The mixture of liquefied and gaseous fuel moved to the lower portion of the reservoir  115  is flown through a second pathway  405  positioned at the lower portion of the reservoir  115  and spouted upwardly through a first pathway  220  formed by the partition  215 . 
         [0050]      FIG. 3  is a perspective view of a reservoir cup according to an exemplary embodiment of the present invention. 
         [0051]    As shown in  FIG. 3 , the second recovery hole  210 , the groove  300 , and the retainer  263  are formed at the reservoir cup  205  as explained above. 
         [0052]    The second recovery hole  210  is formed at the lower surface  230  of the reservoir cup  205 , and the groove  300  has a shape corresponding to the partition  215  formed at the interior surface of the reservoir  115 . 
         [0053]      FIG. 4  is a perspective view of a reservoir according to an exemplary embodiment of the present invention. 
         [0054]    As shown in  FIG. 4 , a connector  400 , a second pathway  405  and the partition  215  are formed at a lower portion of the reservoir  115 . 
         [0055]    The connector  400  connects one distal end portion of the recovery pipe  105  and one end of the second pathway  405 . The other end of the second pathway  405  is connected with a distal end portion of the first pathway  220 . The mixture of liquefied and gaseous fuel recovered through the recovery pipe  105  passes through the second pathway  405  into the first pathway  220 . 
         [0056]    The partition  215  comprises a first partition  215   a  and a second partition  215   b  forced at an interior surface of the reservoir  115  and the first pathway  220  is configured to be enclosed by a portion of the interior surface of the reservoir  115 , the first partition  215   a , and the second partition  215   b.    
         [0057]    The mixture of liquefied and gaseous fuel recovered through the recovery pipe  105  passing through the second pathway  405  is spouted upwardly through the first pathway  220 . 
         [0058]    Once the mixture of liquefied and gaseous fuel is spouted upwardly through the first pathway  220 , the liquefied fuel is separated from the mixture of the liquefied fuel and gaseous fuel by gravity. Then, the separated liquefied fuel flows over the rim  250  of the reservoir cup  205 . Accordingly, the rim  250  of the reservoir cup  205  functions as preventing the separated liquefied fuel from overflowing the reservoir cup  205 , reserving the liquefied fuel until flowing into the retainer  263  of the reservoir cup  205  to make the flown liquefied fuel stable and thus reduces occurrence of cavitations in the separated liquefied fuel. 
         [0059]    The liquefied fuel reserved temporarily on the lower surface  230  of the reservoir cup  205  flows into the retainer  263  through at least an inlet hole  265  formed at mounting brackets  225  as show in  FIG. 3 . The mounting brackets  225  are formed along a circumference of a mounting hole  260  positioned on a upper portion of the retainer  263 . 
         [0060]    The gas separated from the mixture may be released through the first recovery hole  130  and the supply hole  140  of the cover  120 . In another embodiment of the present invention, the cover  120  may have at least a gas hole (not shown) to release the gas more effectively. 
         [0061]    Particularly, according to the present exemplary embodiment, noise occurring in separating the liquefied fuel from the mixture of the liquefied fuel and gaseous fuel may be reduced while the recovered fuel passes through the recovery pipe  105 , the connector  400 , the second pathway  405 , and the first pathway  220 . Furthermore, as shown in  FIG. 1 , since the cover  120  covers an upper portion of the reservoir  115 , noise may further reduced. 
         [0062]      FIG. 5  is a cross-sectional view taken along a line I-I of  FIG. 2 . 
         [0063]    As shown in  FIG. 5 , the recovery pipe  105  penetrates the cover  120  through a first recovery hole  130  (shown in  FIG. 1 ) and the reservoir cup  205  through the second recovery hole  210  (shown in  FIG.3 ), and is connected to the connector  400  positioned at the lower portion of the reservoir  115 . 
         [0064]    In an embodiment of the present invention, a sucked LPI fuel  505  sucked through a suction hole  520  is moved to the fuel pump  510  through a passageway (not shown) positioned at the lower portion of the reservoir  115 . Then the sucked LPI fuel  505  is supplied to the injector by the fuel pump  510  through the supply pipe  110 . 
         [0065]    In another embodiment of the present invention, a part of the sucked LPI fuel  505  sucked through the inlet hole  520  may be bifurcated to the second pathway  405  to join the recovered fuel  500  already moved downwardly through the recovery pipe  105 , and then spouted upwardly through the first pathway  220  formed by the partition  215  as explained above. 
         [0066]    The mixture of liquefied and gaseous fuel is moved to a space between the lower surface  230  of the reservoir cup  205  and the cover  120  through the first pathway  220 . The liquefied fuel is separated by gravity force from the mixture of the liquefied fuel and gaseous fuel at the space. 
         [0067]    As described above, since one end of the recovery pipe is mounted in a reservoir enclosed by a cover, noise may be easily reduced according to an exemplary embodiment of the present invention. 
         [0068]    In addition, since a separator that separates liquefied fuel from the mixture of the liquefied fuel and gaseous fuel is integrally formed with the fuel pump, assembly efficiency of a fuel system may be improved and volume of the fuel system may be reduced. 
         [0069]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.