Abstract:
The invention relates to a pressure regulator for a fuel delivery system of an internal combustion engine for regulating a fuel pressure, including a valve, which has a valve ball that is pressed against a valve seat in the closed position by the action of a valve leaf spring. A segment of a hemisphere of the valve ball oriented toward the valve leaf spring protrudes into a recess associated with the valve leaf spring. This improves the noise behavior and regulating behavior of the pressure regulator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a 35 USC 371 application of PCT/DE 02/04515 filed on Dec. 10, 2002. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention is directed to an improved pressure regulator for a fuel delivery system of an internal combustion engine for regulating a fuel pressure, including a valve, which has a valve ball that is pressed against a valve seat in the closed position by the action of a valve leaf spring. 
   2. Description of the Prior Art 
   A pressure regulator of the type with which this invention is concerned is disclosed in the previously unpublished DE 101 07 223 A1, in which the valve leaf spring is supported in articulating fashion and an arm of the valve leaf spring, which is disposed on the end oriented toward the valve seat in relation to the articulated support, and an arm of the valve leaf spring disposed on the end opposite from the valve seat are supported on a supporting body in such a way that a torque equilibrium prevails in the valve leaf spring. The prestressing force generated by the supporting body is transmitted by the valve leaf spring to the valve ball in the form of a closing force. If fuel pressure prevails in the pressure inlet that is of sufficient magnitude to generate a compressive force that is greater than the closing force acting on the valve ball, then the valve ball lifts up from the valve seat and unblocks a particular opening cross section so that fuel can flow to the pressure outlet. 
   SUMMARY AND ADVANTAGES OF THE INVENTION 
   The regulator according to the invention produces an improved noise behavior and improved fuel regulating behavior. 
   According to a preferred embodiment of the invention, the valve ball protrudes into a recess associated with the ball or the leaf spring and contacts the valve leaf spring; between an edge of the recess and the valve ball, there is a slight amount of play, and the segment of the valve ball is constituted by a spherical segment. 
   Preferably, the recess is constituted by an annular opening of a damping ring, which is disposed between the valve ball and a surface of the valve leaf spring oriented toward the valve ball and is held against the valve leaf spring by the valve ball. This produces a quasi-positively engaging connection between the valve ball and the damping ring in a plane parallel to the valve leaf spring and friction forces can be generated between the damping ring, the valve leaf spring, and the valve ball, which dampen oscillating movements of the valve ball. As a result, noise caused by oscillations of the valve ball is either perceptibly reduced or no longer occurs at all. Since such a damping ring is relatively small and is situated in the immediate vicinity of the valve leaf spring, it does not disturb a flow of fuel surrounding the valve ball. Furthermore, the friction-based damping ring only damps the oscillation movements of the valve ball, but does not limit its movement play space, so that it is still possible for the valve ball to execute centering movements in the valve seat and the tightness of the valve in the closed position remains assured. 
   According to a modification of the preferred embodiment, the damping ring is constituted by a ring that is comprised of an elastomer and has a circular cross section. Alternatively, the damping ring can be comprised of a plastic formed body that is produced by means of cutting machining or by means of injection molding. In both cases, it is extremely simple to produce and assemble the damping rings since they are simple, circular components and are simply inserted between the valve leaf spring and valve ball without requiring alteration to the valve leaf spring or the valve ball. 
   In another embodiment of the invention, oscillations of the valve ball in relation to the valve leaf spring are also damped in that the fuel, which is conveyed into the interior of the pressure regulator and therefore also into the vicinity of the valve ball, constitutes a fluid cushion between the edge of the recess and the segment of the valve ball protruding into it, and this cushion deforms when the valve ball oscillates. In this connection, fluid layers or fluid molecules are moved in relation to one another and internal friction is generated in the fluid cushion, which has a damping effect with regard to oscillations of the valve ball. Because there is still movement play between the edge of the recess and the valve ball, the valve ball is prevented from being guided in a restricted fashion. 
   According to a modification of this embodiment, the segment of the valve ball is constituted by a spherical segment and the recess is constituted by a groove extending along the longitudinal span of the leaf spring. Because this produces a spatially limited fluid cushion mainly between the longitudinal edge of the groove and the valve ball, this measure predominantly damps oscillations occurring in the direction lateral to the longitudinal span of the valve leaf spring. 
   On the whole, the deliberate reduction of oscillations and noise achieved with the measures according to the invention result in an improved regulating behavior of the pressure regulator. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the invention will become apparent from the description contained herein below, with reference to the drawings, in which: 
       FIG. 1  shows a cross section through a preferred embodiment of a pressure regulator according to the invention; 
       FIG. 2  shows a sectional view along the line II—II in  FIG. 1 ; 
       FIG. 3  shows a sectional depiction of another embodiment; 
       FIG. 4  shows a sectional depiction of another embodiment; and 
       FIG. 5  shows a view from beneath of a valve leaf spring in the direction of the arrows V—V in FIG.  4 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   According to a preferred embodiment, the pressure regulator, which is labeled as a whole in  FIG. 1  with the reference numeral  1  and is shown in a closed position there, is fastened to a fuel pump, not shown for reasons of scale, which is disposed in a fuel tank of a motor vehicle, and serves to regulate the fuel pressure in the fuel system of an autoignition internal combustion engine. The pressure regulator  1  has a housing  2  with an L-shaped cross section; in a housing neck that is drawn upward, an opening  4  is provided, which connects an interior  6  of the housing  2  to the fuel tank. At the bottom, a connection fitting  10  that constitutes a pressure inlet  8  protrudes into the housing  2  and is connected to a pressure line, not shown, of the fuel system; fuel returning from a fuel distributor flows through this pressure line. 
   At the end, the connection fitting  10  is provided with a valve seat  12  that has a conical surface  14  for centering a valve ball  18 . Instead of being embodied directly on the connection fitting  10 , the valve seat  12  can also be embodied on the housing  2 ; in this instance, the housing  2  and the valve seat  12  are embodied, for example, as a one-piece injection molded part that has been finished with cutting machining. For example, the cone angle of the conical surface  14  is 60 degrees. The action of a valve leaf spring  16  presses the valve ball  18  against the valve seat  12 . The valve leaf spring  16 , the valve ball  18 , and the valve seat  12  combine to form an overflow valve  20  of the pressure regulator  1 . The valve ball  18  can be made of steel, ceramic, or plastic; for example, its diameter is 3 mm to 12 mm. 
   The valve leaf spring  16  preferably has an angular form, comprised of two arms  22 ,  24  extending essentially at right angles to each other and can rotate around a fulcrum axle  26 , which is supported in the housing  2  and extends crosswise to the longitudinal span of the valve leaf spring  16  and perpendicular to a plane containing the center axis  28  of the valve seat  12 . The fulcrum axle  26  also extends in the region of an imaginary abutting line of the two arms  22 ,  24  of the valve leaf spring  16 . For example, the overall length of the coiled valve leaf spring is 10 to 40 mm and its width is approx. 5 mm to 20 mm. The distance of the center axis  28  of the valve seat  12  from the fulcrum axle is preferably 8 mm to 35 mm. 
   A damping ring  29  is disposed between the valve seat arm  22  of the valve leaf spring  16  oriented toward the valve seat, which arm preferably extends perpendicular to the center axis  28  of the valve seat, and the valve ball  18  whose crown contacts the valve leaf spring  16 . More precisely stated, the valve ball  18  protrudes with a spherical segment  31  of its hemisphere oriented toward the valve leaf spring  16  into an annular opening  37  of the damping ring  29  and holds the ring against the valve leaf spring  16 . The diameters of the annular opening  37  and the valve ball  18  are preferably selected in such a way that a slight amount of play in the form of a narrow gap  33  remains between the valve leaf spring  16  and the damping ring  29 . A prestressing force engages the arm  24  of the valve leaf spring disposed on the end opposite from the valve seat  12  in relation to the fulcrum axis  26  and generates a force on the arm  22  oriented toward the valve seat that pushes the valve ball  18  against the valve seat  12 . This prestressing force is preferably produced by a prestressed leaf spring  30 , which extends essentially parallel to the arm  24  of the valve leaf spring  16  on the end opposite from the valve seat  12 . The prestressed leaf spring  30  is preferably embodied so as to be of one piece with a cover  32  that closes the housing  2  of the pressure regulator  1  at the bottom; in the installed position, this cover  32  is engaged from behind by a radial, outer annular shoulder  34  of the connecting fitting  10 , and extends away from this shoulder at right angles. The free end  36  of the prestressed leaf spring  30  is bent toward the arm  24  of the valve leaf spring  16  on the end opposite from the valve seat  12  and engages in a rounded shape  38  on it in such a way that a prestressing force generated by the prestressed leaf spring  30  is introduced essentially at right angles into the arm  24  of the valve leaf spring  16 . With its bent end  36 , the prestressed leaf spring  30  exerts a torque on the articulatingly supported valve leaf spring  16 , which pushes the valve ball  18  against the valve seat  12 . The magnitude of the closing force, which acts as a reaction on the top of the valve ball  18  due to the prestressing force of the prestressed leaf spring  30 , is produced as a function of the lever ratios selected for the two arms  22 ,  24 . Torque equilibrium then prevails in the valve leaf spring  16 . 
   According to the exemplary embodiment in  FIG. 2 , the circumferential damping ring  29  preferably has a circular cross section and is comprised of an elastomer. Alternatively, the damping ring  29   a  according to the embodiment in  FIG. 3  can be constituted by a plastic formed body that is produced by means of cutting machining or by means of injection molding, whose inner rim oriented toward the valve ball  18  is provided with a bevel  42  or has a seat surface in the form of a spherical zone that is embodied to be complementary to the valve ball  18 . Instead of being made of plastic, the damping ring  29 ,  29   a  can also be made of another material, for example steel. The decisive factor is that during operation, friction forces are generated between the damping ring  29 ,  29   a,  the valve leaf spring  16 , and the valve ball  18 , which on the one hand, are of sufficient magnitude to damp oscillation movements of the valve ball  18 , but on the other hand, are not so great that they prevent the valve ball  18  from being centered in the valve seat  12  when the overflow valve  20  closes. According to another embodiment that is not shown, the damping ring  29 ,  29   a  is not placed loosely around the valve ball  18 , but instead also contacts the valve leaf spring  16  in addition to the valve ball  18  without movement play, for example by being clamped between the valve ball  18  and the valve leaf spring  16  and thus being elastically spread out. 
   In the additional exemplary embodiment of the invention according to  FIGS. 4 and 5 , parts that remain the same and function in the same way as in the preceding example are provided with the same reference numerals. In this instance, the surface  44  of the valve leaf spring  16  oriented toward the valve ball  18  is provided with a recess  46  into which a spherical segment  48  of the valve ball  18  protrudes in such a way that on the one hand, the crown  50  of the valve ball  18  contacts a bottom  52  of the recess  46  and on the other hand, a play space  55  remains on all sides between the edge  54  of the recess  46  and the valve ball  18 . Preferably, the recess is constituted by a groove  46  extending along the longitudinal span of the valve leaf spring  16 , as depicted in the view in  FIG. 5 , in which the valve leaf spring  16  is shown from beneath, without the valve ball  18 . Preferably, the groove  46  does not extend over the entire length of the arm  22  of the valve leaf spring  16  oriented toward the valve seat, but instead extends a certain distance toward both ends starting from the center axis  28  of the valve seat  12 . The play space  55  between the edge  54  of the groove  46  and the valve ball  18  should also permit tolerance-induced axial deviations between the center axis  28  of the valve seat  12  and a center line  56  of the groove  46  so that the valve ball  18  can execute centering movements in relation to the valve seat  12 . Alternatively, instead of a groove  46 , a circular blind hole or a blind hole with a polygonal or arbitrarily shaped edge can constitute the recess in the valve leaf spring  16 . 
   In view of this, the pressure regulator  1  functions as follows: if fuel pressure prevails at the pressure inlet  8  that is of sufficient magnitude to generate a compressive force that is greater than the closing force acting on the valve ball  18 , then the valve ball  18  lifts up from the valve seat  12  and unblocks a particular opening cross section so that fuel can flow into the interior  6  of the housing and from there to the pressure outlet  4 . Due to the elastic properties of the valve leaf spring  16 , the opening cross section increases with increasing fuel volumes, whereas the pressure difference between the pressure inlet  8  and the pressure outlet  4  only increases slightly and in approximately linear fashion. 
   The invention, however, is not limited to a pressure regulator of this kind. Rather, the pressure regulator according to the invention can also be a pressure regulator in which the magnitude of the outlet pressure differs from the inlet pressure and can be adjusted. 
   The foregoing relates to preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.