Abstract:
A high-pressure hose includes a rubber tube, a pair of steel tubes connected to each end of the rubber tube, and a pulsation damping member installed in the rubber tube, one end of the damping member being fixed in the steel tube connected to a downstream end of the rubber tube by means of a ring.

Description:
BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a high-pressure hose, and in particular, to an improved high pressure fuel hose capable of avoiding pulsation noise generated when fluid flows through the hose. 
     (b) Description of the Related Art 
     FIG. 1 shows a schematic diagram of a common automotive fuel supply to system used in a vehicle. Fuel stored in a fuel tank  2  is supplied to a high-pressure pump  8  via a fuel filter  6  by a fuel pump  4 . Then, the fuel is fed to the fuel delivery system  10  by the high-pressure pump  8  so as to be injected to combustion chambers of an engine by fuel injectors (not shown) connected to the fuel delivery system, on the basis of signals from an Electronic Control Unit (ECU)  12 . Surplus fuel not used in the fuel delivery system  10  returns to the fuel tank  2  through return lines. 
     In this fuel supply system, as the fuel pump  4  delivers the fuel to the high pressure pump  8  with a relatively low pressure and the high pressure pump  8  feeds the fuel received from the fuel pump  4  to the fuel delivery system  10  with a high pressure, disposed between the high pressure pump  8  and the fuel delivery system  10  is a high pressure hose. 
     FIG. 5 shows a prior art high pressure hose. The high-pressure hose  100  is made out of a rubber material incorporating a reinforcement layer such as braided wire or textile. 
     Even though the reinforced high pressure hose  100  provides sufficient resistance to the high pressure, the reinforced high pressure hose has a drawback in that it can not dampen pulsations caused by the high pressure of the fluid flow. That is, since the high pressure pump is operated by a cam mechanism actuated by an engine, the high pressure pump periodically generates pressure, thereby generating pulsation causing a booming noise while a vehicle is driving or idling. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to solve the above problems of the prior art. 
     It is an object of the present invention to provide an improved high pressure hose capable of damping a pulsation of fluid flow so as to avoid generation of booming noise caused by the pulsation. 
     To achieve the above object, the high-pressure hose of the present invention comprises a rubber tube, a pair of steel tubes connected to each end of the rubber tube, and a pulsation damping member installed in the rubber tube, one end of the damping member being fixed in the steel tube connected to a downstream end of the rubber tube by a ring. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention: 
     FIG. 1 is a schematic diagram of a common automotive fuel supply system; 
     FIG. 2 is a sectional view of a high-pressure hose according to a preferred embodiment of the present invention; 
     FIG. 3 is a partial enlarged view of the high-pressure hose depicted in FIG. 2; 
     FIG. 4 is a partial enlarged view of a high pressure hose according to another preferred embodiment of the present invention; and 
     FIG. 5 is a sectional view of a prior art high-pressure hose. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will be described hereinafter with reference to the accompanying drawings. 
     FIG. 2 shows a high-pressure hose according to a preferred embodiment of the present invention. 
     A high-pressure hose  20  comprises a rubber tube  22  connected to steel pipes  26  at downstream and upstream ends and a pulsation damping member  24  fixed by a ring member  32  at a downstream end of the rubber tube  22 , the ring member  32  being tightly fitted in to the steel pipe  26  connected to the downstream end of the rubber tube  22 . 
     The rubber tube  22  incorporates reinforcement layers such as braided wire or textile for providing sufficient pressure resistance. 
     The pulsation damping member  24  is formed by spirally winding a plastic strip  28  which is stepped in a widthwise direction such that the plastic strip  28  is continuously overlapped along each side by the adjacent spiral, with a gap between the overlaps (see FIG.  3 ). Accordingly, the windings of the plastic strip  28  form a pipe of which the downstream end is fixed at the rubber tube  22  by the ring  32 , and the upstream end remains free. The downstream end of the hose  20  is opened by only an opening of the downstream end of the pulsation damping member  24  and is sealed by the ring  32  such that the fluid can flow out through the opening of the pulsation damping member  24 . The upstream end of the pulsation member  24  is an opened free end. 
     The operation of the high-pressure hose according to the preferred embodiment of the present invention will be described hereinafter. 
     Once the fluid is introduced into the high-pressure hose  20  by a pumping operation of the high-pressure pump  8  (see FIG.  1 ), the fluid flows through both the inner and outer channels of the pulsation damping member  24 . However, the fluid flowing through the outer channel of the pulsation damping member  24  cannot proceed because the downstream end of the pulsation damping member  24  is circumferentially sealed by a ring  32  such that the fluid squeezes into the inner channel through the gap spirally formed along the pulsation damping member  24 . Accordingly, the pulsations generated by periodic pumping operations of the high-pressure pump  8  are dampened while the fluid in the outer channel is squeezed into the inner channel of the pulsation damping member  24 . 
     FIG. 4 is a partial enlarged view showing the high pressure hose according to another preferred embodiment of the present invention. 
     As shown in FIG. 4, in this embodiment, a dual pulsation damping member  40  is installed in the rubber pipe  22 . The dual pulsation damping member  40  comprises inner and outer pipes  42  and  44  that are formed in such a way that a plurality of passage holes  46  are alternatively formed in both pipes  42  and  44  in their longitudinal direction. Accordingly, the fluid in the outer channel of the pulsation damping member  24  squeezes into the inner channel via the holes  46  of the inner and outer pipes  42  and  44 . The damping effect of the dual pulsation damping member  40  according to the second preferred embodiment is identical to that of the pulsation damping member  24  according to the first preferred embodiment. 
     Though the inner and outer pipes can be made out of steel, it is preferred to use plastic pipes because of lower manufacturing costs. 
     As described above, since the high-pressure hose according to the first and second preferred embodiments is provided with the pulsation damping member, the pulsations generated by periodical pumping operations of the high-pressure pump are dampened while the fluid in the outer channel is squeezed into the inner channel of the pulsation damping members. Furthermore, by preventing the fluid from fluctuating in the hose, the pulsation noise which is generated can be reduced. 
     While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, 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.