Abstract:
A pressure regulator valve has a housing that defines a fluid passage and a flat seat disposed around an opening of the fluid passage and exit ports. A pin with a raised conforming elastomeric embossment that contacts the seat when the valve is closed is axially disposed in the housing. The pin is biased to maintain the elastomeric embossment in contact with the seat to maintain the valve closed and control an opening pressure of the valve. Flow of fluid through and out of the pressure regulator valve housing is controlled through adjustment of a level of this biasing. The fluid flows across the flat seat and between the flat seat and the embossment when the valve is open in such a manner that the flow is generally laminar and such that the valve minimizes pressure gain at the onset of flow.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates generally to pressure relief and pressure regulating valves, and more particularly to valve seals that minimize pressure gain with increasing flow in pressure regulator valves and the like, specifically well suited for use in fuel injection and other systems where minimizing pressure increases with increasing flow is desirable for improved system performance. 
         [0003]    2. Description of the Prior Art 
         [0004]    Internal combustion fuel injection systems typically require some form of pressure controlling device, either a pressure regulator or a pressure relief valve to maintain an appropriate fuel pressure at the injectors. Conventional fuel pressure relief valves and regulators utilize metal-to-metal seals in the pressure relief valve. The metal-to-metal sealing elements are resistive to surface depression of the adjacent sealing surfaces; resulting in a direct flow path with minimum pressure drop. However, the metal-to-metal seals are subject to high leakage rates as the two sealing surfaces are rigid, nonconforming and highly sensitive to the effects of contamination. One solution to this problem employs rubber sealing pressure regulator valves. Such fuel pressure regulator valves comprise a rubber sealing element which is held in intimate contact with a metal seat, the seat having a raised boss that contacts, and depresses into the surface of a planar rubber element. In such a traditional valve design the annular metal sealing surface contacts the relatively thick flat rubber pad to affect the valve seal. Because of the relative softness, and viscoelastic properties, of the rubber the metal ring causes a permanent indention into the rubber surface. This surface depression typically causes a permanent “compression set” in the rubber. As the valve begins to open, the fluid flow is constrained to conform to the complex channel defined by surface deformation in the rubber, which results in a labyrinth flow path as the pressure regulator valve begins to open. The long and convoluted flow path causes a significant pressure drop at initial valve opening. 
         [0005]    Metal-to-metal sealed devices are more expensive and have a higher leak rate than rubber sealing pressure regulator valves. Leakage is typically associated with increased difficulty starting the associated vehicle. However, conventional rubber sealing pressure relief valves and regulators have a greater pressure drop, and less linear flow characteristics. These liabilities limit the application of rubber sealing pressure regulator valves. 
       SUMMARY 
       [0006]    The present invention is directed to systems and methods which minimize the pressure drop in a pressure regulator valve during low flow conditions. 
         [0007]    The present invention reverses the arrangement of sealing elements in a rubber sealing pressure regulator valve, creating a raised boss in the rubber component that in contact with a planar metal seat. The metal seat, being resistant to “compression set”, maintains its planar surface allowing a direct flow path that minimizes pressure drop of the flowing fuel. 
         [0008]    The present invention reduces the leakage of the pressure regulator valve when it is closed, compared to the conventional metal-to-metal pressure regulator valve seal. This reduced leakage is advantageous to the fuel injection system&#39;s ability to hold pressure while the vehicle is off. 
         [0009]    Thus, in accordance with various embodiments of the present invention a pressure regulator valve, such as a fuel pressure regulator valve, has a housing that defines a fluid passage and a flat seat disposed around an opening of the fluid passage. The housing also preferably has exit ports. A pin is preferably axially disposed in the housing. This pin preferably has a raised conforming elastomeric embossment that contacts the seat when the valve is closed. For example the pin might have a raised annulus over which the elastomeric embossment is molded. This elastomeric overmold may have a thickness in a range of about 0.002 inches to about 0.020 inches in thickness, preferably about 0.007 inches in thickness. The elastomer may be a fluoroelastomer, a nitrile, or the like selected for its chemical stability when exposed to the fluid used in the system. The pin is preferably biased, such as through exertion of compressive spring force on the pin, to maintain the elastomer embossment in contact with the seat to maintain the valve closed and control an opening pressure of the valve. This biasing is preferably adjustable and may be provided by a spring disposed in the housing, in contact with the pin and an adjustment screw disposed in the housing to contact and adjust the biasing of the spring. The spring may be a coil spring, an elastomeric spring, cantilever spring arrangement, a conical spring or other similar biasing member. 
         [0010]    In operation, such embodiments of a pressure regulator valve provide a flow channel, with the flat seat defined around the flow channel. The raised conforming elastomeric embossment defined on the pin, such as by overmolding the annulus defined by the pin with an elastomeric material, is axially contained in the housing. The pin is preferably biased such that the embossment is in contact with the seat when the valve is closed and flow of fluid through and out of the pressure regulator valve housing is controlled through a level of the biasing. The fluid flows across the flat seat and between the flat seat and the embossment when the valve is open in such a manner that the flow is generally linear with streamlined flow characteristics. 
         [0011]    In accordance with embodiments of the present pressure regulator valve, a hydraulic mechanism or electrically actuated mechanism may be used to apply the biasing at a level directed by automatic or programmed logic. Similarly, in accordance with some embodiments, a hydraulic or electrically actuated mechanism might be employed to varying the tension in a biasing spring or the like according to automatic or programmed logic. 
         [0012]    With respect to pressure drop to flow, the present invention provides the fuel injection system, or the like in which it is deployed, a lower pressure drop as the pressure regulator valve actuates and a more linear pressure drop-versus-flow relationship across the span of fluid flow rates through which the pressure regulator valve operates. The reduced pressure drop improves the robustness of the fuel injector performance, as the fuel injectors are exposed to lower pressure excursions. This linear relationship improves the effectiveness of the fuel injection control system by increasing the predictability of the pressure drop. 
         [0013]    The reduced pressure drop provided by the present valve results in several advantages. First, the reduced pressure drop is itself an advantage. Secondly, since the flow path remains fundamentally unchanged as the flow is increased, the rate of change in pressure drop with flow is constant, improving the linearity of the flow-to-pressure drop relationship. And lastly, the pressure drop does not vary as the properties of the rubber change, either over time, as the valve ages, or between individual valves. 
         [0014]    The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The accompanying drawings, which are incorporated in and form part of the specification in which like numerals designate like parts, illustrate embodiments of the present invention and together with the description, serve to explain the principles of the invention. In the drawings: 
           [0016]      FIG. 1  is a partially fragmented, generally cross-sectional view of an embodiment of a pressure regulator valve employing a seal in accordance with the present invention; 
           [0017]      FIG. 2  is an enlarged, more detailed, partially fragmented, generally cross-sectional, view of an embodiment of a pin for use in accordance with the present invention; 
           [0018]      FIG. 3  is a partially fragmented, generally cross-sectional view of the pressure regulator valve embodiment of  FIG. 1 , showing the valve open, with resulting linear streamlined flow; 
           [0019]      FIG. 4  is a partially fragmented, generally cross-sectional view of a regulator valve embodiment of the present invention employing an example of hydraulically actuated biasing mechanism; and 
           [0020]      FIG. 5  is a partially fragmented, generally cross-sectional view of a regulator valve embodiment of the present invention employing an example of an electronically actuated bias adjustment mechanism. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]      FIG. 1  is a partially fragmented, generally cross-sectional view of an embodiment of pressure regulator valve  100  employing seal  101  in accordance with the present invention. Fuel pressure regulator valve  100  is primarily comprised of housing  105  defining fuel passage  106  and seat  107 . Pin  110  is disposed in housing  105 . Pin  110  has raised conforming elastomeric embossment  101  that functions as a seal that contacts seat  107  when valve  100  is closed. Spring  112 , disposed in the housing, biases pin  110  to maintain rubber embossment  101  in contact with seat  107  to maintain valve  100  closed until fuel pressure on the opposite side of pin  110 , such as in fluid passage  106 , overcomes tension in spring  112 . Adjusting screw  115 , or a similar mechanism, which may be disposed in housing  105 , is used to adjust the biasing provided by spring  112 . The embodiment shown in  FIG. 1  also employs inlet filter  118 , which may be a nylon mesh screen  119 , held in a nylon plastic housing, snapped onto valve housing  105 . Such a filter screen typically has a mesh opening of between twenty and fifty microns. O-ring  120  may be fit onto housing  105  to provide a seal between the valve and it&#39;s mounting, which may be a fuel pump body or other fuel system structure, either in the fuel tank or elsewhere in the fuel system. The o-ring may typically be made from Fluoroelastomer (FKM) rubber, but any rubber that is compatible with the fuel being handled may be used. 
         [0022]    Housing body  105  preferably provides a flow path, between filter  118  and seal  101 , such as fuel passage  106 , and from seal  101  through flow discharge ports  122 . Housing bore  124 , above seal  101 , operatively accommodates valve pin  110  and constrains the length of valve spring  112 . Preferably, pin  100  is contained axially in bore  124  of body  105 . Housing  105  defines seal seat  107 , which interfaces with seal  101  of pin  110 . Housing  105  may be made of brass, optionally plated with nickel, or the like. However, most any non-corrosive metal, or other metal with an anti-corrosive coating, can be employed for housing  105 . Alternatively, plastic construction, using moisture and fuel resistant plastics may be used. 
         [0023]      FIG. 2  is an enlarged, more detailed, partially fragmented, generally cross-sectional, view of an embodiment of generally cylindrical pin  110 , showing rubber seal  101  overmolded onto sealing annulus  230 . Overmolded seal  101  may extend beyond annulus  230  and onto the bottom of flange  235 . Flange  235  may align pin  110  in bore  124 . Pin  110  also preferably defines recess  237 , which may be generally circular, for mating with, and aligning pin  110  with, spring  112 . Alternatively, pin  110  might define a boss or other structure protruding from pin  110  to mate with spring  112  and align it with pin  110 . The relative thinness of overmolded rubber seal  101  over sealing annulus  230 , and provides repeatable and durable performance in the present valve. A relative shallow depth for annulus  230  may further facilitate this performance repeatability and durability. Preferably, the thickness of seal  101 , over annulus  230  is sufficiently thin to limit the total distention of the shape of seal  101  and any rubber swelling. Preferably the shape of seal  101  is maintained by the underlying reinforcing metal of annulus  230 . 
         [0024]    Pin  110  may be nickel plated brass, although it may be made from any metal, with appropriate anti-corrosive properties or coating. Alternatively pin  110  may be made from plastic. Seal  101  may made from FKM, but other rubber compounds suitable for use with the fuel being handled may be used. 
         [0025]    Returning to  FIG. 1 , spring  112  is held in compression between the top of pin  110  and adjusting screw  115 . The spring may be stainless steel, but other spring materials that have suitable corrosion resistant properties with respect to the fuel being handled may be used. Furthermore, the spring may be a coil spring, as illustrated in  FIG. 1 , but it might also be an elastomeric structure of some sort or a cantilevered or conical spring. Valve opening pressure is calibrated by adjusting the axial position of screw  115  in threads  137  defined in body  105  until a correct spring force is applied to pin  110  to balance a desired fluid pressure below seal  101 , providing a correct opening pressure for valve  100 , after which screw  103  is locked in position. In the embodiment shown in  FIG. 1 , an upsetting tool or the like may be used to lock the threads between housing  105  and adjusting screw  115 . However, other arrangements, such as a mechanical lock or adjustable pin, may be used. The adjusting screw may be made of brass, with a nickel coating. However, most any non-corrosive metal or other metal with an anti-corrosive coating or plating could be used to make screw  115 . Also, a plastic construction, using moisture and fuel resistant plastics may be used. Other means of providing the adjustment rather than threads may also be used, as appropriate to the materials of construction and the assembly process. 
         [0026]    With attention directed to  FIG. 3 , the arrangement of components in the present valve provides a substantially different flow path in contrast to the prior art.  FIG. 3  shows valve  100  open, with resulting linear streamlined flow, as indicated by flow arrows. In the present arrangement the metal surface of seat  117 , defined by the housing, is flat and the raised annular ring is preferably formed by a thin layer of rubber  101  molded over a metal reinforcing embossment  230 , or the like. In such embodiments displacement or swelling that occurs in the rubber, over time does not change the flow path in the valve. Preferably a thin section thickness for the rubber embossment limits the total distention of the shape, which is maintained by the underlying reinforcing metal. As the valve begins to open the fluid flow will be straight, parallel to the metal surface of the housings seat, without any changes in direction or constraint through a contorted path. The result is lower pressure drop at the onset of flow. 
         [0027]    With respect to pressure drop to flow, the present invention provides a fuel injection system a lower pressure drop as the pressure regulator valve actuates and a more linear pressure drop-versus-flow relationship across the span of fluid flow rates through which the pressure regulator valve operates. The reduced pressure drop improves the robustness of the fuel injector performance, as the fuel injectors are exposed to lower pressure excursions. This linear relationship improves the effectiveness of the fuel injection control system by increasing the predictability of the pressure drop. 
         [0028]    In certain embodiments of a pressure regulator valve, biasing force may, as diagrammatically depicted in  FIG. 4 , be applied by a mechanism ( 412 ) other than a spring or the like, and/or may, such as diagrammatically illustrated in  FIG. 5 , be adjusted by a mechanism ( 514 ) other than a manually adjusted screw or the like. 
         [0029]    For example,  FIG. 4  shows a partially fragmented view of regulator valve embodiment  400  of the present invention employing example  412  of a hydraulically actuated biasing mechanism. Illustrated hydraulically actuated biasing mechanism  412  might be locally controlled such as by a locally (or remotely) located hydraulic (or pneumatic) valve supplying fluidic pressure to mechanism  412 . This control valve might, in turn, be controlled by a vehicle Engine Control Module (ECM), or the like, in a fuel injection system, or by a similar control mechanism in other systems employing valve  400 . Mechanism  412 , which might take the form of a hydraulic (slave) cylinder, or the like, might bias pin  110 , via push rod  415 , to maintain rubber embossment  101  in contact with seat  107  to maintain valve  400  closed until fuel pressure on the opposite side of pin  110  overcomes the pressure exerted by cylinder  412 . Alternatively, a hydraulic or pneumatic mechanism similar to mechanism  412 , may be used to adjust the tension of a spring ( 112 ) in other embodiments of a pressure regulator valve (rather than replace it). 
         [0030]    As another example,  FIG. 5  shows a partially fragmented view of regulator valve embodiment  500  of the present invention employing example  515  of an electronically actuated bias adjustment mechanism. In valve  500  the biasing force exerted by spring  112  is adjusted or regulated by an electrical stepper motor, or the like, generally illustrated as  517  in  FIG. 5 . In the illustrated example, stepper motor  517  might turn screw pintle  515  to adjust the tension in spring  112  and in turn the biasing spring  112  imparts to pin  110  to maintain rubber embossment  101  in contact with seat  107  and to maintain valve  100  closed until fuel pressure on the opposite side of pin  110  overcomes the tension imparted in spring  112 . Alternatively, an electrical solenoid, or the like, might be used to adjust bias in spring  112 , rather than a stepper motor and pintle arrangement, as illustrated. 
         [0031]    These or other mechanisms for applying hydraulic pressure may be interchangeably used to bias pin  110  and/or to adjust the biasing force applied to pin  110  with these or other electronic mechanisms. Regardless, such embodiments can provide variation of biasing force in accordance with an automatic or programmed logic, such as might be used in a fuel injection system to provide an added, higher degree of engine control for environmental, emissions or power optimization. 
         [0032]    Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.