Abstract:
A high-pressure fuel pump includes a tappet assembly having a tappet for receiving a roller, and a fuel pump adaptor, the high-pressure fuel pump, wherein a reciprocal motion of the tappet assembly is guided by the fuel pump adaptor and a downward motion thereof is limited by the fuel pump adaptor, is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to Korean Patent Application Number 10-2008-0086349 filed on Sep. 2, 2008, the entire contents of which application is incorporated herein for all purposes by this reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a high-pressure fuel pump, and more particularly to a high-pressure fuel pump provided with a guide groove therein. 
         [0004]    2. Description of Related Art 
         [0005]    Generally, it has been disclosed that a high-pressure fuel pump for vehicles includes a cam rotating together with a camshaft that rotates by engine torque, a tappet assembly including a tappet and a roller moving upwardly by the rotation of the cam, and a return spring providing downward force to the tappet assembly. 
         [0006]    The tappet assembly applied to such a high-pressure fuel pump is mounted at an interior circumference of a fuel pump adaptor having a cylindrical shape in a rolling-contact manner. 
         [0007]    When the cam rotates, the tappet assembly including the tappet and the roller reciprocate while the roller contacts the cam. 
         [0008]    Therefore, fuel for generating power of an internal combustion engine flows. 
         [0009]    The tappet assembly should be assembled such that the roller has the same rotational direction as the cam so as to prevent friction or abrasion therebetween. 
         [0010]    However, there is a difficulty with above-mentioned structure in that a worker must synchronize the rotational directions of the roller and the cam. 
         [0011]    The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0012]    Various aspects of the present invention are directed to provide a high-pressure fuel pump having advantages of being able to guide reciprocation of a tappet provided to a fuel pump adaptor, and to allow installation work thereof to be easy and precise. 
         [0013]    In an aspect of the present invention, a high-pressure fuel pump that is provided with a tappet assembly having a tappet for receiving a roller, and a fuel pump adaptor, includes a guide protrusion formed at an exterior circumference of the tappet along a longitudinal direction thereof, and a guide groove formed at an interior circumference of the fuel pump adaptor so as to slidably receive the guide protrusion therein and guide a reciprocal motion of the tappet along the fuel pump adaptor. 
         [0014]    A shoulder may be formed at a lower end of the guide groove and configured and dimensioned to limit a downward movement of the guide protrusion so that the guide protrusion is not disengaged downwardly therefrom, wherein the shoulder is formed at a bottom portion of the fuel pump adaptor. 
         [0015]    A vertical distance between a center of a cam and the shoulder may be between about 15 mm to about 32 mm, the cam being disposed at a bottom portion of the fuel pump adapter. 
         [0016]    The guide protrusion may be spaced from a bottom surface of the tappet with a predetermined distance. 
         [0017]    In another aspect of the present invention, a high-pressure fuel pump is provided with a tappet assembly having a tappet for receiving a roller, and a fuel pump adaptor, wherein a reciprocal motion of the tappet assembly is guided by the fuel pump adaptor and a downward motion thereof is limited by the fuel pump adaptor, wherein a guide protrusion is provided at an exterior circumference of the tappet assembly and engaged with a guide groove formed at an interior circumference of the fuel pump adaptor so as to guide a reciprocal motion of the tappet assembly along the fuel pump adaptor and wherein a shoulder is formed at a lower end of the guide groove and configured and dimensioned to limit a downward movement of the guide protrusion so that the guide protrusion is not disengaged downwardly therefrom. 
         [0018]    The shoulder may be formed at a bottom portion of the fuel pump adaptor. 
         [0019]    A vertical distance between a center of a cam and the shoulder may be between about 15 mm to about 32 mm, the cam being disposed at a bottom portion of the fuel pump adapter. 
         [0020]    The guide protrusion may be spaced from a bottom surface of the tappet with a predetermined distance. 
         [0021]    The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a perspective view showing an exemplary high-pressure fuel pump provided with a guide groove according to the present invention. 
           [0023]      FIG. 2  is a cross-sectional view showing an exemplary high-pressure fuel pump provided with a guide groove according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are 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. 
         [0025]      FIG. 1  is a perspective view showing an exemplary high-pressure fuel pump provided with a guide groove according to the present invention, and  FIG. 2  is a cross-sectional view showing an exemplary high-pressure fuel pump provided with a guide groove according to the present invention. 
         [0026]    As shown in  FIG. 1  and  FIG. 2 , an exemplary high-pressure fuel pump according to the present invention includes a tappet assembly  100 , a fuel pump adaptor  200 , and a cam  230  that is simultaneously rotated with a camshaft. 
         [0027]    The tappet assembly  100  as a conventional structure is provided with the cam  230  that is simultaneously rotated with the camshaft that is rotated by operation of an engine, and is provided with a tappet  110  that is reciprocated when the cam  230  rotates. 
         [0028]    The tappet assembly  100  reciprocates as a result of a ramp of the rotating cam  230 . 
         [0029]    In addition, a tappet roller  120  is interposed between the tappet  110  and the cam  230  for ease of rotation. 
         [0030]    Furthermore, a return spring may be provided so as to generate descent power of the tappet assembly  100 . 
         [0031]    The fuel pump adaptor  200  is provided so as to receive the tappet assembly therein such that the tappet assembly  100  slidably reciprocates. 
         [0032]    A guide protrusion  111  is formed at an exterior circumference of the tappet  110  of the tappet assembly  100  that slides in the interior circumference of the fuel pump adaptor  200 . 
         [0033]    The guide protrusion  111  may be preferably formed to protrude in a length direction of the tappet  110 . 
         [0034]    According to various embodiments of the present invention, it is exemplarily described that a guide protrusion  111  is formed at an exterior circumference of the tappet  110 , but the spirit of the present invention cannot be limited to this, and a plurality of guide protrusions  111  can be provided. 
         [0035]    A guide groove  210  is formed at an interior circumference of the fuel pump adaptor  200  in a length direction thereof with a shape slidably receiving that of the guide protrusion  111 . 
         [0036]    Therefore, the tappet  110  is reciprocated and the guide protrusion  111  is guided at the same time in a reciprocating direction by the guide groove  210 . 
         [0037]    In addition, a catching dent or shoulder  220  may be provided at the bottom of the guide groove  210 . 
         [0038]    When the tappet assembly  100  is inserted into the fuel pump adaptor  200 , the tappet assembly is prevented from being disengaged therefrom since the guide protrusion  111  is stopped by the catching dent  220 . 
         [0039]    In addition, when the guide protrusion  111  is snugly fitted into the guide groove  210 , the rotation directions of the cam  230  and tappet roller  120  are synchronized. Thus, friction and abrasion therebetween are reduced, and installation work can be executed very quickly and precisely. 
         [0040]    Meanwhile, as shown in  FIG. 2 , a vertical distance D between the point C at the center of the cam  230  may be determined by a person of ordinary skill in the art. 
         [0041]    Considering performance, the type and capacity of the pump may be needed to determine the distance D. 
         [0042]    Herein, the distance may be in a range of 15 mm to 32 mm, but the distance can be adjusted by experiment or experience. 
         [0043]    The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.