Patent Publication Number: US-7210460-B2

Title: Bypass pressure regulator

Description:
FIELD OF THE INVENTION 
     This invention relates to pressure regulators and more particularly to a bypass pressure regulator for controlling the pressure and flow rate of liquid. 
     BACKGROUND OF THE INVENTION 
     In many liquid supply systems, and particularly fuel injection systems for combustion engines, it is desirable to supply liquid fuel to the fuel injectors from a fuel pump which continuously delivers a quantity of liquid fuel sufficient to supply the maximum fuel demand of the engine. Consequently, when the engine is operating under conditions which require less fuel, there is an excess of fuel being delivered from the fuel pump. This is especially true when the engine is idling and has an extremely low fuel demand while the fuel pump is still delivering a large quantity. 
     In such systems, a bypass pressure regulator is utilized to divert or bypass the excess fuel from the needed supply of fuel consumed by the engine. Preferably, the bypass liquid fuel is diverted back to the liquid supply source such as a fuel tank. In fuel system applications, the fuel pump is typically located inside the fuel tank. The bypass pressure regulator can be located in the tank and immediately downstream of the fuel pump thus diverting bypass fuel directly back into the fuel tank, or it can be located further downstream of the fuel pump and downstream of an injector fuel rail utilized as a manifold which communicates with the injectors. If the bypass pressure regulator is mounted downstream of the fuel injectors, a bypass fuel return line is needed to return the excess fuel back into the fuel tank. Whether the bypass pressure regulator is internal or external to the fuel tank, when utilizing a regulator, the fuel pump can operate continuously maintaining a high rate of fuel output to accommodate a rapidly changing demand for fuel at the engine. 
     Some previous bypass pressure regulators, such as that disclosed in U.S. Pat. No. 5,727,529, use a flexible diaphragm in a can which is spring biased to close a bypass passage. The diaphragm is responsive to an increase in fuel pressure acting thereon and when displaced, permits the fuel to flow through the bypass passage to be returned to the fuel tank. Although generally satisfactory in performance, and beneficial for the ability to accommodate thermally expanding or excess fuel, these bypass pressure regulators are expensive to manufacture because of the diaphragm and numerous parts. Furthermore, the diaphragm regulators are relatively large, and have a relatively slow response time causing undesirable fuel pressure pulsations which can affect the performance of the engine and can generate undesirable levels of noise in the fuel system or other liquid systems. 
     Other bypass pressure regulators, such as that disclosed in U.S. Pat. No. 5,975,061 and incorporated herein by reference, do not utilize a diaphragm. As best illustrated in  FIG. 1 , marked prior art, the bypass pressure regulator  20  typically has a valve body  22  defining a bypass passage  24  having an inlet  26  in communication with a fuel pump (not shown) and an outlet  28  in communication with a fuel tank (not shown). A valve assembly  30  is received in and controls the flow of fuel through the bypass passage  24 . The valve assembly  30  is composed of many difficult to manufacture and assemble parts including an enlarged, disc-like valve head  32  attached concentrically to a valve shank  34  at one end and attached to a disc  36  at an opposite end. A spring  38  biases the regulator closed, and is compressed axially between the disc  36  and a radially inward projecting shoulder  40  of the valve body  22  through which the shank  34  projects in an upstream direction. A valve seat  42  carried by the body  22  faces generally downstream with respect to the bypass fuel flow (identified by arrow  44 ) and a resilient annular ring  46  attached to the enlarged head  32  releasably seals to the seat  42  when the regulator  20  is closed. So as not to obstruct bypass fuel flow  44  through the passage  24  and to expose the valve head  32  to the acting fuel pressure, numerous orifices  48  are formed in the disc  36  and shoulder  40  of the valve body  22  lending toward additional manufacturing costs and complexities. 
     Furthermore and unfortunately, known bypass pressure regulators like regulator  20  do not maintain a constant pressure drop through the valve under varying flow rates. In operation, the spring force and generally the area of the exposed head  32  determine the fuel pressure at which the valve will “crack” or begin to open. When the valve assembly  30  first starts to open, flow through the annulus between the valve head  32  and seat  42  develops at high velocities relative to the surrounding fuel. This high velocity produces a low pressure region  50  exerting a force on the valve assembly  30  which is additive to the spring force and thus tends to close the valve assembly  30 . In known bypass pressure regulators this low pressure region can lead to unstable oscillations of the valve assembly  30 , fuel pressure flow rate fluctuations and noise of the valve assembly. In extreme cases, the regulator can be damaged by the hammering effect of the components. Yet further, known bypass pressure regulators are not easily integrated into other components of a typical fuel system or pump module of a combustion engine, are relatively complex, and relatively expensive to manufacture. 
     SUMMARY OF THE INVENTION 
     A low cost bypass pressure regulator for liquid fuel flowing preferably in a returnless fuel system for a combustion engine communicates operatively with a conduit or storage vessel which flows fuel from a fuel pump of the fuel system to at least one fuel injector of the combustion engine. The pressure regulator preferably has a valve head disposed at least in-part in a valve chamber defined by a circumferentially continuous inner surface carried by a valve body and which transitions radially outward with respect to a center axis and in a downstream direction. The valve head preferably tapers radially inward with respect to the center axis in an upstream direction and from a peripheral outer edge of the head. 
     When the valve head is in a closed position, the valve head is seated sealably against a seat carried by the body and the peripheral outer edge which is spaced radially downstream of the seat is radially spaced from, but fitted closely to the continuous inner surface of the body thus defining a close fit region there-between. When the valve head is in an open position, the tapered valve head is spaced appreciably away from the seat and the peripheral outer edge is spaced appreciably radially inward from the body continuous inner surface thus defining a free flow region there-between. The movement of the valve head from closed to open is in a downstream direction, hence the free flow region is generally located downstream of the continuous inner surface portion which defines in-part the close fit region when the valve head is closed. Because the flow cross section spaced axially downstream of the seat generally enlarges as the valve head opens, a high velocity of liquid flow is moved away from the seat thus reducing the otherwise low pressure at the seat. By reducing or eliminating low pressure at the seat, oscillation of the valve head is reduced or eliminated. This also reduces fuel pressure and flow rate fluctuations and noise. 
     Preferably, the continuous inner surface of the body has a circular crest generally formed by the congruent meeting of a substantially cylindrical portion and a substantially conical or tapered portion of the continuous inner surface. When the valve head is in the closed position, its peripheral outer edge is substantially aligned axially to the circular crest to form the close fit region. When the valve head is in the open position, the peripheral outer edge shifts downstream axially well into the conical portion of the continuous inner surface thus forming the larger free flow region. 
     Preferably and advantageously, the flow cross section represented by the close fit region remains substantially constant and accounts for valve head-to-seat wear and manufacturing tolerances because the continuous inner surface in this region is cylindrical. Thus any shifting of the closed valve head over an extended period of time (i.e. wear) would simply shift the peripheral outer edge slightly upstream and the edge remains aligned axially to the cylindrical portion. 
     Preferably, the valve head is biased closed, not by a conventional diaphragm, but by a compression spring compressed axially between the valve head and a guide member of the valve body generally located downstream of the valve head. A valve stem preferably projects from the head through the guide member and preferably through the spring. 
     Objects, feature, and advantages of this invention include a bypass pressure regulator which produces a more uniform regulated output pressure and flow rate, is relatively inexpensive and versatile, quieter and less prone to producing noise, has a valve head which is less likely to oscillate, is robust, reliable, durable, maintenance free, of relatively simple design, easy to assemble, of economical manufacture and assembly and in service has a long useful life. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects, features and advantages of this invention will be apparent from the following detailed description of the preferred embodiments and best mode, appended claims and accompanying drawings in which: 
         FIG. 1  is a cross section of a prior art bypass pressure regulator; 
         FIG. 2  is a schematic diagram of a fuel system utilizing a bypass pressure regulator embodying this invention; 
         FIG. 3  is a cross section of the bypass pressure regulator shown in a closed position and integrated into a supply fuel conduit for pressure regulated fuel flow; 
         FIG. 4  is an enlarged partial cross section of the bypass pressure regulator taken from circle  4  of  FIG. 3 ; 
         FIG. 5  is a partial cross section of the bypass pressure regulator similar to  FIG. 4  but shown in an open position; 
         FIG. 6  is a cross section of the bypass pressure regulator taken along line  6 — 6  of  FIG. 4 ; 
         FIG. 7  is a second embodiment of the bypass pressure regulator integrated into a fuel filter cartridge utilized in a fuel pump module in a fuel tank; 
         FIG. 8  is an exploded cross sectional perspective view of the bypass pressure regulator of  FIG. 7 ; 
         FIG. 9  is a cross sectional perspective view of the bypass pressure regulator of  FIG. 7 ; and 
         FIG. 10  is a perspective view of a guide member of the embodiments of the bypass pressure regulator. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 3  illustrates a bypass pressure regulator  120  of the present invention utilized preferably in a flowing liquid conduit  122  which generally defines a supply passage or channel  138 .  FIG. 2  illustrates one preferred application of the regulator  120  in a preferably returnless fuel supply system  124  for a fuel injected combustion engine  126 . In this particular application, the system  124  includes an electric fuel pump  128  preferably in a module located in a fuel tank  130 . A pre-filter  132  is located generally at an inlet  134  of the fuel pump  128 . The pump  128  supplies pressurized fuel at its outlet  136  which communicates directly with the channel  138  defined by the conduit  122  and to the bypass pressure regulator  120 . The total output fuel flow from the pump  128  (indicated by arrow  139 ) is generally divided by the pressure regulator  120  as supply fuel to the engine (indicated by arrow  140 ) and bypass fuel (indicated by arrow  142 ). The total fuel output  139  flows into the bypass pressure regulator  120 , or is generally exposed to an inlet of the regulator. The regulator  120  diverts the bypass fuel  142  generally back into the fuel tank  130  while controlling the fuel pressure of the supply fuel  140  which continues to flow in the channel  138  and to at least one fuel injector  144  preferably mounted to a fuel rail  146  of the combustion engine  126 . Preferably, the supply fuel also flows through a filter  148  located in the conduit  122  downstream of the bypass pressure regulator  120 . 
     The bypass pressure regulator  120  is integrated or generally housed in the conduit  122  of the returnless fuel supply system  124 . The versatility of the regulator  120  is generally contributed substantially by a valve body  150  of the regulator  120  which is preferably comprised of three components; an annular retainer  152  engaged sealably to the conduit  122  at an opening  154 , a dome structure  156  disposed about a center axis  158  and having a continuous base or end rim  160  fitted sealably to the retainer  152 , and a guide member  162  preferably engaged axially between the end rim  160  of the dome structure  156  and the retainer  154 . The dome structure  156  projects axially from the base rim  160 , through the opening  154  of the conduit  122  and generally into the channel  138  where it converges generally to a distal end or an annular shaped apex  164  of the structure  150 . 
     As best illustrated in  FIGS. 3–5 , the pressure regulator  120  preferably has an enlarged valve head  166  disposed substantially in a valve chamber  168  defined by a circumferentially continuous inner surface  167  that radially transitions outward in a downstream direction. The inner surface  167  is carried by the dome structure  150  and is orientated substantially concentric to the center axis  158 . The head  66  preferably tapers radially inward in an upstream direction from a downstream facing annular shelf  170  and to a generally distal point  172 . When the valve head  166  is in a closed position  178 , the distal point  172  of the head  166  extends through an inlet port  174  of the chamber  168  generally at the apex  164 . The inlet port  174  is defined generally by an annular valve seat  176  carried by the dome structure  156  which releasably seals to the tapered valve head  166 . 
     A valve stem or shank  180 , disposed concentrically to the center axis  158 , projects axially in a downstream direction from the annular shelf  170  carried by the enlarged valve head  166  and generally through a bypass passage  182  in the dome structure  156  which communicates axially with the valve chamber  168  at an outlet port  184  of the chamber  168 . The shank  180  extends through and is supported and guided by a substantially cylindrical collar portion  186  of the guide member  162  which is located in the bypass passage  182 . A support structure  188  of the guide member  162  generally projects radially outward from a downstream end  246  of the collar portion  186 , across a hole  190  of the retainer  152  which communicates with the bypass passage  182 , and attaches rigidly to the dome structure  156  and/or retainer  152 . The valve head  166  is biased closed against the valve seat  176  by a coiled compression spring  192  compressed between the annular shelf  170  of the enlarged valve head  166  and a distal annular end  193  of the collar portion  186  of the guide member  162 . 
     The valve chamber  168  has an upstream bowl-shaped or rounded section  194  communicating directly with the inlet port  174 , and a downstream conical frustum section  196  which generally expands radially outward from the rounded section  194  and communicates axially between the rounded section  194  and the outlet port  184 . The bypass passage  182  is located concentrically to and directly downstream from the frustum section  196  and communicates with section  196  at the outlet port  184 . The rounded section  194  is generally defined by an annular concave portion  198  and a cylindrical portion  200  of the inner surface  167 . Portion  198  extends radially outward from the seat  176  as it extends axially in a downstream direction to the cylindrical portion  200 . The frustum section  196  of the valve chamber  168  is generally defined by a radially expanding or frusto conical portion  202  of the inner surface  167  which extends axially, and radially expands in a downstream direction, from the cylindrical portion  200  and to a substantially cylindrical wall  204  of the dome structure  156  which defines the bypass passage  182  that extends axially to the end or base rim  160 . For purposes of illustration, the union of the cylindrical wall  204  with the cylindrical portion  200  of the inner surface  167  is coaxial with the outlet port  184 . 
     When the tapered valve head  166  is in the closed position  178 , a peripheral outer edge  206 , which generally defines the outer periphery of the valve head shelf  170 , is aligned axially with the cylindrical portion  200  of the inner surface  167  preferably at or slightly upstream of a peripheral inner edge or circular crest  208  of the inner surface  167  formed by the congruent joining of the cylindrical portion  200  and the conical portion  202 . The peripheral outer edge  206  of the valve head  166  and the cylindrical portion  200  of the dome structure  156  are slightly spaced apart radially from one-another just enough to prevent contact, thus providing interference-free seating of the valve head  166  with the seat  176 . This small radial space or close fit region  210  between the peripheral outer edge  206  and the circular crest  208  generally enlarges to a free flow region  212  as the valve head  166  moves from the closed position  178  to an open position  214  (as best shown in  FIG. 5 ). 
     When fuel pressure in the channel  138  of the conduit  122  generally exceeds the biasing force of the coiled compression spring  192 , compressed axially between the upstream end  193  of the collar portion  186  of the guide member  162  and the annular shelf  170  of the tapered valve head  166 , the biased closed valve head moves axially away from the seat  176  toward the open position  214 , cracking the valve open and slightly compressing the spring  216  axially. Also when opening, the peripheral outer edge  206  of the tapered head  166  moves axially past the circular crest  208  and into the frustum section  196  of the valve chamber  168 . Hence, upon initial cracking open of the pressure regulator  120 , the close fit region  210  begins to enlarge because the radial distance between the peripheral outer edge  206  and the dome structure  156  increases due to the tapered conical portion  202  of the inner surface  167 . This shift of the close fit region  210  to the free flow region  212  moves the high velocity of fuel flow away from the valve seat  176  which would otherwise create a low pressure region causing the valve head  166  to repeatedly briefly close and open or oscillate. Thus, enlargement of the close fit region  210  to the free flow region  212  greatly reduces and substantially prevents oscillation of the valve head  166  and reduces valve noise and seat wear. 
     Also for reducing valve noise and improving wear and sealing between the seat  176  and the head  166 , the head has a resilient leading cover or glove  220  which covers a base segment  222  of the head  166 . The cover  220  has a circular shoulder  224  which projects radially inward and press fits into a circular groove  226  of the base segment  222  which is spaced axially upstream of the annular shelf  170  and opens radially outward to receive the shoulder  224 . The shank  180  and base segment  222  are preferably unitary and formed preferably of metal for durability, but could also be formed of injection molded plastic or other rigid materials. The cover  220  is preferably made of a fuel resistant synthetic rubber or polymer material. 
     Preferably and advantageously, the flow cross section represented by the close fit region  210  remains substantially constant and compensates or allows for valve head-to-seat wear and manufacturing tolerances because the continuous inner surface  167  in this region  210  is cylindrical. Thus any axial shifting of the valve head  166  while generally in the closed position  178  over an extended period of time (i.e. wear) would simply shift the peripheral outer edge  206  slightly upstream and the edge remains aligned axially to the cylindrical portion  204 . 
     As best illustrated in  FIGS. 5 and 6 , the bypass pressure regulator  120  can further be described with respect to three imaginary and substantially parallel planes  228 ,  230 ,  232 , spaced apart axially and each being disposed perpendicular to the center axis  158 . The valve seat  176  and generally the inlet port  174  are located in the first imaginary plane  228 . The circular crest  208  is located in the second imaginary plane  230  and the radial clearance between the peripheral outer edge  206  and the conical portion  202  which represents the free flow region  212  is located generally in the third imaginary plane  232  when the pressure regulator is in the open position  214 . Generally then, the rounded section  194  of the valve chamber  168  is defined axially between the first and second imaginary planes  228 ,  230 , and the frustum or expanding section  196  of the valve chamber  168  extends from second imaginary plane  230  and communicates through the third imaginary plane  232  to the outlet port  184  located downstream of the third plane  232 . When the valve head  166  is in the closed position  178  (shown in  FIG. 4 ), the peripheral outer edge  206  and the annular shelf  170  generally lie in the second imaginary plane  230  and the tapered head  166  preferably projects axially through the first imaginary plane  230 . When the valve head  166  is in the open position  214 , the peripheral outer edge  206  and the annular shelf  170  generally lie in the third imaginary plane  232 . 
     Because the valve head  166  is tapered, a diameter  234  of the seat  176  which lies in the first imaginary plane  228  is substantially smaller than a diameter  236  of the peripheral outer edge  206 . To create the close fit region  210  when the valve head  166  is closed, the peripheral outer edge diameter  236  is slightly smaller than a diameter  238  of the cylindrical portion  200  and circular crest  208  of the inner surface  167 . Because the conical portion  202  of the inner surface  167  tapers radially outward in a downstream direction, the crest diameter  238  is appreciably smaller than a diameter  240  of the conical portion  202  which generally lies in the third imaginary plane  232 . Preferably, and when the valve head  166  is in the fully open position  214 , the annular flow area at the second imaginary plane  230  is generally equal to or larger than the annular flow area at the first imaginary plane  228 , at the inlet port  174 , and generally equal to or smaller than the annular flow area at the third imaginary plane  232  at the free flow region  212 . This generally eliminates any pressure drop transients at the planes  230 ,  232 , regardless of valve position, and thus generally places any fluid flow dynamics which may impact design considerations of the valve generally at the inlet port  174 , simplifying sizing of the bypass pressure regulator  120  between varying applications. 
     The robust design of the valve head  166  and dome structure  156  has an axial tolerance which accounts for axial compression and/or wear of the resilient cover  220  with the seat  176 . Slight wear or varying axial compression of the valve head cover  220  could cause the head  166  and peripheral outer edge  206  to shift slightly upstream essentially shifting the closed position  178  slightly upstream. The flow cross section of the close fit region  210 , however, remains substantially constant because the peripheral outer edge  206  which is initially aligned axially to about the circular crest  208  can move slightly upstream due to wear, but remains aligned axially to the cylindrical portion  200  of the inner surface  167 . 
     During assembly of the bypass pressure regulator  120 , the cover  220  is preferably press fitted or overmolded into the circular groove  226  in the base segment  222  of the head  166 . The shank  180  is then inserted axially through the coiled compression spring  216  and through the collar portion  186  of the guide member  162 . The pre-assembled collar portion  186 , the shank  180 , the valve head  166  and the spring  192  are inserted in the dome structure  156  at the end rim  160  of the cylindrical wall  204 . The collar portion  186  is easily centered to the center axis  158  by locating two chamfered distal ends  242  of two diametrically opposed legs  244  of the support structure  188  of the guide member  162 , which project axially outward from a base end  246  of the collar portion, to the chamfered base end or rim  160  of the dome structure  156 . When fitting the distal ends  242 , the taper characteristic of the valve head  166  centers the head to the seat  176  and thus to the center axis  158 . Also, the spring  192  which bears axially between the shelf  170  and the distal end  193  of the collar portion  186  axially compresses holding the head  166  on the seat  176 . The base or rim end  160  of the dome structure  156  is then slid axially into a counter bore  248  of the retainer  152  until the base end  160  axially contacts a radially inward projecting annular shoulder  250  of the retainer  152 . The shoulder  250  generally defines the bore or hole  190  for exiting bypass flow  142  from the bypass pressure regulator  120 . 
     As thus assembled, the bypass pressure regulator  120  is a completed unit and is ready for integration into any variety of applications. Preferably, and as illustrated in  FIG. 3 , the retainer  152  carries male threads or a threaded exterior face  252  which thread into female threads  254  carried preferably by the conduit  122  at the opening  154  or any other type of vessel carrying pressurized liquid. Alternatively, the retainer  152  cam be press fitted into the conduit  122 . As an additional sealing feature, the conduit  122  has a circular shelf  256  projecting radially inward which seals axially against a gasket  258  which is preferably an o-ring disposed in a circular groove  260  opened axially outward and carried by the retainer  152 . 
     Referring to  FIGS. 7–9 , a second application of a bypass pressure regulator  120 ′ is illustrated wherein similar elements to that of the first application are identified with the same numeral and an added “prime” symbol. A returnless fuel supply system  124 ′ for a combustion engine has a fuel tank  130 ′ defining a fuel chamber  300  and a versatile fuel pump module  302  located in the chamber. During assembly, the module  302  is inserted through an access hole  304  of the tank  130 ′ which is covered sealably by a flange  306  of the module  302 . 
     Suspended rigidly from the flange  306  in the chamber  300  of the tank  130 ′ are two spring loaded shocks or vertical displacement struts  308  (one shown) which fit slidably into strut guides (not shown) of a structural pod  310  to yieldably support the pod  310  of the fuel pump module  302  so that a bottom or bottom cover plate  312  of the pod is generally located and held against a bottom wall of the tank  130 ′ even if the tank walls should slightly flex, expand, or contract. The pod  310  houses and supports numerous components including a fuel pump  128 ′, an electric motor  312  coupled to the pump, and a filter cartridge  314  having a filter element  316  and an integrated bypass pressure regulator  120 ′. Fuel flows generally between the components via the pod  310  thus eliminating the need for conventional hoses, tubes and fittings. Power leads or wires  318  are routed from the motor  312  and through a sealing grommet  320  of the flange  306 . 
     The pod  310  carries an inner cylindrical first surface  322  defining a first bore  324  having a central axis  326  extending substantially vertically, and an inner cylindrical second surface  328  defining a second bore  330  spaced radially outward from the first bore  324  and having a central axis  158 ′ disposed substantially parallel to the central axis  326  of the first bore  324 . The pump and motor  128 ′,  312  are assembled in the first bore  324  and the filter cartridge  314  is assembled in the second bore  330 . 
     During manufacture, components of the fuel pump  128 ′ are preferably assembled into the first bore  324  through an open top end and are generally nestled against a continuous bottom shoulder  332  projecting radially and unitarily inward from the first cylindrical surface  322 . After the fuel pump  128 ′ is assembled, the pump motor  312  which has a stator encircling an armature with a drive shaft  334  journaled for rotation by a pair of bearings is inserted into the first bore  324  from above and coupled mechanically to the pump  128 ′. The open end is then sealed-off by a cap  336  which preferably carries one set of the bearings. At least one electrical lead  318  extends through the end cap  336 . When operating, fuel enters the pump  128 ′ through an inlet or bottom port  134 ′ generally defined by the shoulder  332  of the pod  310  and pressurized fuel exits the pump  128 ′ and flows into the second bore  330  via an outlet or fuel passage  136 ′ defined by the pod  310  and communicating through the first and second surfaces  322 ,  328 . 
     The reversible filter cartridge  314  is preferably pre-assembled with the integral bypass pressure regulator  120 ′ located radially inward from the cylindrical fuel filter element  316 . The filter element  316  is located axially between an inverted funnel-like primary end retainer  338  for flowing the supply fuel identified by arrow  140 ′ and a secondary end retainer  152 ′ of the cartridge  314  for flowing the bypass fuel identified by arrow  142 ′. Each disc-like retainer  338 ,  152 ′ defines a circular groove  340  (as best shown in  FIG. 8 ) which oppose one-another in an axial direction for seating opposite ends  342  of the cylindrical filter element  316  and spacing the element radially inward from the second cylindrical surface  328  to maximize filtration efficiency and filter surface area. This construction also prevents shifting of the filter element  316  within the second bore  330  and prevents bypassing of the fuel around the filter element  316 . 
     The primary end retainer  338  has an inverted bowl-like base portion  340  which carries a cylindrical inward face  342  that defines in-part a fuel cavity  344  of the channel  138 ′ held at system operating pressure by the bypass pressure regulator  120 ′, and a collar portion  346  which projects upward from the base portion  340  and defines a supply fuel outlet passage  350  of the channel  138 ′ that communicates axially with the cavity  344 . The collar portion  346  projects into a counter bore  352  defined by a cylindrical third surface  354  carried by the pod  310 . An outer radial face  356  of the base portion  340  defines a continuous slot  358  which seats a resilient seal or preferable O-ring  360  that seals to the second surface  328  of the second bore  330 . An outer radial face  362  of the collar portion  346  also defines a continuous slot  364  which seats an O-ring  366  that seals to the third surface  354  of the counter bore  352 , and likewise, an outer radial face  252 ′ of the secondary end retainer  152 ′ defines a continuous slot or groove  260 ′ which seats an O-ring  258 ′ that seals to the second surface  328  of the second bore  330 . All three O-rings  360 ,  366 ,  258 ′ and the seating arrangement of the filter element  316  to the retainers  152 ′  338  assure that all of the fuel flowing from the fuel passage  136 ′ is filtered before entering the pressurized fuel cavity  344  of the channel  138 ′. 
     After filtration, the fuel which enters the cavity  344  primarily flows upward through the fuel outlet passage  350  of the collar portion  346 , through an upward projecting barbed nipple  368  of the pod  310  and into a flexible tube  370  of the conduit  122 ′ press fitted to the nipple  368  and extending upward to couple to a similar nipple  372  projecting downward from the flange  306  (as best shown in  FIG. 7 ). From the flexible tube  370 , the fuel generally flows out of the tank. When system fuel pressure is exceeded by the pump  128 ′, the bypass pressure regulator  120 ′ will open allowing bypass fuel  142 ′ to flow from the pressure cavity  344  and through the secondary retainer  152 ′ back to the tank chamber  300 . 
     A dome structure  156 ′ of the bypass pressure regulator  120 ′ projects axially and concentrically upward from the retainer  152 ′ and is spaced radially inward from and generally aligned axially to the filter element  316 . The pressurized fuel cavity  344  is thus generally defined axially between the primary end retainer  338  and an annular face  372  of the retainer  152 ′ which spans radially between a continuous groove  374 , which receives an end rim  160 ′ of the dome structure  156 ′, and the dome structure  156 ′. The cavity  344  is generally defined radially between the dome structure  156 ′ and the outer filter element  316 . 
     When fuel system pressure is exceeded, the biased closed bypass pressure regulator  120 ′ opens, compressing a biasing spring  192 ′ axially as a valve head  166 ′ moves axially downward away from a seat  176 ′ carried by the dome structure  156 ′. Bypass fuel  142 ′ flows through an inlet port  174 ′ generally defined by the seat  176 ′ and downward through a valve chamber  168 ′ and communicating bypass passage  182 ′, both defined by the dome structure  156 ′. The bypass fuel  142 ′ then exits the second bore  330  through a hole  190 ′ of the retainer  152 ′ and through a slightly larger hole  374  of the cover  312  for holding the filter cartridge  314  axially in the second bore  330 . During manufacture, at least one and preferably three upward projecting flex arms  378  of the cover  312  snap fit to the pod  310  to lock the cartridge  314  within the second bore  330 . Preferably, the arms  378  each have a slot  380  which receives a ramped tab  382  projecting outward from the pod  310 , thus locking the cover  312  in-place. 
     While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. For instance, the conduit  122  can be a liquid storage pressure vessel and the channel  138  can be a pressure chamber for the storage of liquid, and not necessarily the flow of liquid. In such an application, the bypass pressure regulator  120  will actually function as a pressure relief regulator. It is not intended herein to mention all the possible equivalent forms or ramification of the invention. It is understood that terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention as defined by the following claims.