Abstract:
A fuel vapor pressure regulator by which the input pressure of an input fluid is regulated by the opening and closing of a valve unit controlled by a piston pressure sensor, the operation of which is, in turn, controlled by a movement of a preset bias, the output pressure of the fluid delivered by the regulator, and a biasing pressure that reflects the operating demands of the utilization unit to which the fluid is delivered.

Description:
[0001]     This application is a divisional of U.S. patent application Ser. No. 10/304,839 filed Nov. 26, 2002 entitled FLUID FLOW PRESSURE REGULATOR. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates, in general, to the regulation of the pressure of a fluid flow and, in particular, to a fluid flow pressure regulator for use in regulating the pressure of liquid petroleum gas delivered for the fueling of a vehicle.  
       BACKGROUND OF THE INVENTION  
       [0003]     There are a wide variety of units, known to those skilled in art, for metering fluids in amounts needed to meet the operational requirements of the equipment to which the fluids are delivered. Currently, the regulators of liquid petroleum gas fueled vehicles typically include an integral vaporizer to generate saturated vapor that is burned as fuel in the engine of the vehicle. Other regulators, differently arranged, are used in vapor fed systems in conjunction with a discrete vaporizer to provide the liquid petroleum gas to the regulator and, in turn, to the engine to burn as fuel. These regulators have a fixed output pressure.  
         [0004]     Many of the liquid petroleum gas regulators known to those skilled in the art fall short of operating with the desired efficiency. This is so because the regulators function without control of the changing operational requirements of the engine to which the liquid petroleum gas vapor is supplied.  
         [0005]     In contrast, U.S. Pat. No. 3,741,240 to Berriman is an example of a fluid regulator that operates in response to the operational demands of remote fluid utilization equipment. The range of control of the regulator disclosed in this patent, however, is somewhat limited by the use of a thin metal flexible diaphragm that responds to pressures changes in the output fluid flow and the level of the vacuum from the manifold to regulate the output pressure.  
       SUMMARY OF THE INVENTION  
       [0006]     A fluid flow pressure regulator, constructed in accordance with the present invention, includes a housing having an inlet port through which a fuel is introduced at an input pressure, an outlet port through which the fuel is discharged at an output pressure, and a bias port through which a biasing pressure is introduced. Also included in this fluid flow pressure regulator is a valve unit in the housing between the inlet port and the outlet port for regulating the pressure of fuel flow from the inlet port to the outlet port. A fluid flow pressure regulator, constructed in accordance with the present invention, further includes a piston in the housing coupled to the valve unit and responsive to the output pressure at the outlet port for urging the valve unit toward closing and the biasing pressure introduced through the bias port for one of urging the valve toward closing and urging the valve to open. A spring acting on the piston against the outlet pressure to urge the valve unit to close also is included in this fluid flow pressure regulator.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a cross-sectional view of a first embodiment of a fluid flow pressure regulator constructed in accordance with the present invention.  
         [0008]      FIG. 2  is a cross-sectional view of a second embodiment of a piston pressure sensor of a fluid flow pressure regulator constructed in accordance with the present invention.  
         [0009]      FIG. 3  is a cross-sectional view of a third embodiment of a piston pressure sensor of a fluid flow pressure regulator constructed in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0010]     Referring to  FIG. 1 , a fluid flow pressure regulator, constructed in accordance with the present invention, includes a housing  10  having an inlet port  12  through which a fluid is introduced at a supply pressure and an outlet port  14  through which the fluid is discharged at an output pressure. Fluid is supplied from a fluid supply  15 , such as a fuel storage system and vaporizer, at an input pressure and fluid is discharged to a fluid utilization  16 , such as an engine, at an output pressure.  
         [0011]     Housing  10  also has a bias port  17  through which a biasing pressure is introduced, a cavity  18  in fluid communication with the bias port, and an aspirator passage  20  extending between the outlet port and the cavity through which the output pressure is conducted from the outlet port to the cavity. As illustrated, housing  10  is in two parts  10   a  and  10   b  that are held together by suitable means not shown.  
         [0012]     The source of biasing pressure can be, for example, an engine manifold and the biasing pressure can be either a partial vacuum or greater than atmospheric pressure, depending on the operational demand of the fluid utilization (e.g., an engine) to which the fluid is delivered. The effect of the biasing pressure is explained below.  
         [0013]     A fluid flow pressure regulator, constructed in accordance with the present invention, also includes a valve assembly within housing  10  for regulating the pressure of fluid flow from inlet port  12  to outlet port  14 . This valve assembly includes a valve unit composed of a nozzle  22  between inlet port  12  and outlet port  14  through which fluid flows from the inlet port to the outlet port and a valve  24  movable toward the nozzle and away from the nozzle. In the  FIG. 1  embodiment of the present invention, valve  24  is a conical poppet valve.  
         [0014]     Also included in the valve assembly are means for urging valve  24  toward nozzle  22 . For the embodiment of the invention being described, such means include a compression spring  26  having a first end bearing against valve  24  and a second end bearing against a plug  28  threaded into housing  10 .  
         [0015]     The valve assembly of  FIG. 1  further includes a pressure set point assembly in cavity  18 . This pressure set point assembly includes a piston pressure sensor  30  and means acting on the piston pressure sensor for urging valve  24  away from nozzle  22 . Piston pressure sensor  30  controls the position of valve  24  relative to nozzle  22  by means of a coupling  32  extending between the piston pressure sensor and the valve and, for the embodiment of the invention being described, a compression spring  34  acts on the piston pressure sensor for urging the valve away from the nozzle. A first end of compression spring  34  bears against a first face  30   a  of piston pressure sensor  30  and a second end of this compression spring bears against a calibration adjustment screw  35  which is threaded into part  10   a  of housing  10  and sealed with a plug  36 . Face  30   a  of piston pressure sensor  30  includes the surface against which spring  34  bears and the edges of the piston pressure sensor at the opening into which spring  34  extends. In effect, piston pressure sensor  30  divides cavity  18  into a first part  18   a  and a second part  18   b . The spring force of spring  34  is high relative to the spring force of spring  26 , so that valve  24 , at the outset and in the absence of any other influences, is spaced from nozzle  22 .  
         [0016]     The valve assembly, and, in particular, piston pressure sensor  30 , is responsive to the biasing pressure introduced through bias port  17  into part  18   a  of cavity  18  and received at face  30   a  of the piston pressure sensor to urge valve  24  away from nozzle  22 . Piston pressure sensor  30  also is responsive to the output pressure conducted from outlet port  14  through aspirator passage  20  into part  18   b  of cavity  18  and received at a second face  30   b  of piston pressure sensor for urging valve  24  toward nozzle  22 . The net effect of the output pressure, the biasing pressure, and spring  34  on piston pressure sensor  30  is either to urge valve  24  toward nozzle  22  or to urge the valve away from the nozzle.  
         [0017]     In operation, when, for example, an ignition switch is turned on, fluid passes from inlet port  12  to outlet port  14  because spring  34 , acting on piston pressure sensor  30 , causes valve  24  to be spaced from nozzle  22  by the effect of the spring  34  on the piston pressure sensor which is transmitted through coupling  32  to the valve. The pressure of the output fluid at outlet port  14  is conducted through aspiration tube  20  to face  30   b  of piston pressure sensor  30 . This output pressure acts on piston pressure sensor  30  against the action of spring  34  and moves valve  24  toward nozzle  22 . This causes a reduction in the output pressure at outlet port  14 . The reduction in output pressure at outlet port  14  reduces the opposition to spring  34  and permits piston pressure sensor to move valve  24  away from nozzle  22 . This operation continues until a balance or equilibrium condition is achieved allowing valve  24  to throttle the flow of fluid based on pressure.  
         [0018]     Also contributing to the balance of forces on piston pressure sensor  34  is the biasing pressure introduced at bias port  17 . When the biasing pressure is a partial vacuum, the biasing pressure opposes the action of spring  34  and causes valve  24  to move toward nozzle  22 . When the biasing pressure is greater than atmospheric pressure (e.g., when the fluid utilization is a supercharged engine or a turbocharged engine), the biasing pressure supports the action of spring  34  and causes valve  24  to move away from nozzle  22 .  
         [0019]     Under steady state conditions, an increased biasing pressure, whether a partial vacuum or greater than atmospheric, acts to effect movement of piston pressure sensor  30  to maximize the spacing between valve  24  and nozzle  22  with an increase in fluid flow and increased output pressure at outlet port  14 . A decreased biasing pressure, whether a partial vacuum or atmospheric, acts to effect movement of piston pressure sensor  30  to minimize the spacing between valve  24  and nozzle  22  with a decrease in fluid flow and decreased output pressure at outlet port  14 .  
         [0020]     For the  FIG. 1  embodiment of the present invention, with the outside diameter of piston pressure sensor  30  the same throughout its length, the biasing pressure ratio is proportional, namely 1:1. This is because the area of face  30   b  of piston pressure sensor  30  over which the output pressure is applied is the same as the area over which the biasing pressure is applied, namely face  30   a  of the piston pressure sensor that includes the surface against which spring  34  bears and the edges of the piston pressure sensor at the opening into which spring  34  extends.  
         [0021]     In the  FIG. 2  embodiment of the piston pressure sensor, the outside diameter of piston pressure sensor  30 ′ is stepped, so that the area of face  30   b ′ of piston pressure sensor over which the output pressure is applied is less than the area over which the biasing pressure is applied, namely face  30   a ′ of the piston pressure sensor that includes the surface against which spring  34  bears and the edges of the piston pressure sensor at the opening into which spring  34  extends. In the  FIG. 2  embodiment of the piston pressure sensor, the biasing pressure ratio is boosted and is greater than 1:1. In the  FIG. 3  embodiment of the piston pressure sensor, the outside diameter of piston pressure sensor  30   b ″ is stepped, so that the area of face  30   b ″ of piston pressure sensor over which the output pressure is applied is greater than the area over which the biasing pressure is applied, namely face  30   a ′ of the piston pressure sensor that includes the surface against which spring  34  bears and the edges of the piston pressure sensor at the opening into which spring  34  extends. In the  FIG. 3  embodiment of the piston pressure sensor, the biasing pressure ratio is reduced and is less than 1:1. The unique requirements of different engine fuel management systems determine the design of the piston pressure sensor. In all other respects, a fluid flow pressure regulator having the piston pressure sensor  30 ′ of  FIG. 2  or the piston pressure sensor  30 ″ of  FIG. 3  is the same as the fluid flow pressure regulator of  FIG. 1   
         [0022]     To avoid input pressure fluctuations affecting the output pressure, a fluid flow pressure regulator, constructed in accordance with the present invention, preferably includes a balanced valve having a piston cylinder  38 , a balance piston  40  movable within piston cylinder  38  and coupled to piston pressure sensor  30  valve  24 . The balanced valve also has a seal  42  between balance piston  40  and piston cylinder  38 . A pressure equalization passage  44  extends through valve  24  and balance piston  40  from the second part  18   b  of cavity  18 . This balanced valve, of conventional construction and operation, counterbalances both the forces acting to move valve  24  toward nozzle  22  due to the input pressure and the forces acting to move valve  24  away from nozzle  22  due to the output pressure.  
         [0023]     When used in the delivery of liquid petroleum gas to an engine, the fluid pressure regulator of the present invention, by operating in response to the operating conditions of the engine, delivers the fuel at a pressure that is most suitable for low emission fuel control system designs. Another important benefit of the present invention is that this pressure regulator can withstand the temperature and vibration requirements of an engine mounted in an automobile.  
         [0024]     Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.