United States Patent [191
`Danowski et a1.
`
`US005164879A
`Patent Number:
`1111
`[45] Date of Patent:
`
`5,164,879
`Nov. 17, 1992
`
`[54] ELECT ROSTATICALLY DISSIPATIVE FUEL
`SYSTEM COMPONENT
`[75] Inventors: Daniel R. Danowski, Richmond, R.l.;
`
`Sun“ K. Kesavan’ Troy, James W. Martin; James S. Pereira,
`
`both of Rehoboth, Mass’
`[73] Assignee: Allied-Signal 1116., Morristown, NJ.
`[21] APP]_ No‘: 724,240
`-
`_
`Jul' 1’ 1991
`[22] Flled'
`Related US. Application Data
`Division of Ser. No. $75,260, Aug. 30, 1990, Pat. No.
`5,076,920.
`
`[62]
`
`[56]
`
`[5]] Int. Cl.5 ............................................ .. B01D 27/08
`[52] US. Cl. .................................. .. 361/215; 210/243;
`210/ 748
`[58] Field of Search ..................... .. 252/511, 518, 519;
`428/364; 264/105; 210/748, 243; 361/212, 215
`References Cited
`U-S- PATENT DOCUMENTS
`3,186,551 6/1965 Domauf
`13
`gulkték ---
`
`,
`
`,
`
`o vm et a.
`
`210/243
`
`-
`
`- - - ~
`
`4,675,143 6/1987 Wakita et al. ..................... .. 264/104
`4,686,071 8/1987 Rosenzweig e1 a1.
`. 264/104
`4,812,247 3/1989 Fahner et al. ................. .. 264/104
`
`0176866 4/1986 European Pal. 011. .
`3918342 6/1990 Fed. Rep. of Germany .
`‘541025 10/1968 Fm“ '
`OTHER PUBLICATIONS
`Effect of Conductivity on Charge Generation in Hy
`drocarbon Fuels Flowing through Fiber Glass Filters,
`?gmilggg igloégiggimerface Sc'ence’ vol’ 32’ N0‘ 3’
`'
`_
`’
`.
`_
`Primary Exammer--Stanley S. S1lverman
`Assistam Examiner-Neil McCarthy
`Attorney’ Agent, or Firm_Ken C‘ Decker; William N_
`Anmnis
`
`ABSTRACT
`[57]
`A fuel system component for a motor vehicle con
`structed from a polymer material to which are added
`t ' l
`t
`l 1' b
`t
`(1
`th
`1 '
`25131551332113,55211211121511, rioig?iiili'ihiiiel
`trically conductive component permits charges gener
`ated by the fuel passing through the component to be
`
`'
`
`-
`
`-
`
`-
`
`_
`
`
`
`----------- ~ 4,196;464 4/1980 Russell
`
`361/215
`
`g
`
`P
`
`4,319,303 3/1982 Thorn . . . . . . . . . . . . .
`
`. . . .. 361/215
`
`quem leaks‘
`
`264/104
`4,378,322 3/1983 Atterbury et al. .
`4,664,971 5/1987 Soens ................................ .. 264/104
`
`4 Claims, 1 Drawing Sheet
`
`42 36 24 I6 26
`
`Cisco Systems, Inc., EX 1051 Page 1
`
`

`

`US. Patent
`
`Nov. 17, 1992
`
`5,164,879
`
`N~ ON 9 ‘N mm, Nv
`
`Cisco Systems, Inc., EX 1051 Page 2
`
`

`

`1
`
`5,164,879
`
`ELECT ROSTATICALLY DISSIPATIVE FUEL
`SYSTEM COMPONENT
`
`5
`
`20
`
`2
`14 and bridges across the inner cavity 28 de?ned within
`the array of media 20. A circumferentially extending
`band of sealing material 30 is dispensed into the end cap
`26, and seals the edges of the pleats comprising the
`media 20 to prevent bypass of fuel around the ends of
`the pleats. A corresponding circumferentially extending
`band of sealing material 32 is dispensed in end cap 34
`_ which closes the opposite end of the inner cavity 28.
`The sealing material 32 seals the opposite edges of the
`pleats comprising the media 20. The outlet ?tting 16
`extends through the end cap 34 to communicate with
`the inner cavity 28. A spring 36 is disposed in the inner
`cavity 28 and engages the inner tips 24 of the media 20
`to prevent inward collapse of the media. The housing 12
`is secured to the metal vehicle body, a portion of which
`is indicated at 38, by a bracket 40. The bracket 40 may
`be either a separate metallic member attached to the
`housing 12 or molded as a part of the housing 12 from
`the same material used for the housing 12. Accordingly,
`fuel communicated into the inlet ?tting 14 is received in
`inlet cavity 42 which is de?ned between the element 18
`and the housing 12. Fuel in the inlet cavity 42 communi
`cates through the media 20 into the inner or outlet cav
`ity 28 which is communicated directly with the outlet
`?tting 16.
`As the fuel communicates through the media 20 from
`inlet cavity 42 to the inner or outlet cavity 28, electrical
`charges are generated, regardless of the type of media
`used. Although the media 20 is most commonly a
`pleated paper media, other materials might be used. As
`the hydrocarbon paraf?n passes through the ?lter me
`dia, electrons are stripped from the outer shell of the
`paraf?n as a result of the impact between the paraf?n
`and the media. Accordingly, the hydrocarbon mole
`cules in the cavity 28 are positively charged, and an
`excess of electrons is present in the inlet cavity 42, so
`that hydrocarbon molecules in the inlet cavity take on
`the characteristics of a negatively charged molecule or
`ion. Thus the fuel in the inlet cavity 42 becomes nega
`tively charged. Although some electrical charge gener
`ation occurs in the fuel lines upstream and downstream
`of the ?lter due to stripping of electrons due to friction
`between the fuel and the walls of the fuel line, the
`charge generation due to the impact of the hydrocarbon
`paraf?n against the media 20 may be as much as several
`orders of magnitude higher than the generation taking
`place in the lines themselves.
`The magnitude of the charge generated in the inlet
`cavity 42 will also be a function of the flow rate through
`the housing 12. In fact, as studies have shown, the
`charge generation in the inlet chamber 42 is almost
`directly proportional to the flow rate through the ?lter
`media 20. Accordingly, fuel ?lters used in recirculatory
`fueling systems, such as electronic fuel injection systems
`where ?ows through the fuel line are substantially
`higher than flows in older carbureted systems, will
`generate a proportionally higher charge level in the
`inlet chamber 42.
`Under undisturbed conditions, the charge generated
`in the inlet cavity 42 would be evenly distributed about
`the ?lter. Accordingly, the charge would then be
`evenly dissipated or passed through the ?lter. However,
`when a grounding plane is within "striking distance” of
`the electrostatic charge in the inlet cavity 42, a dis
`charge takes place from the portion of housing 12 clos
`est to the plane 38 whenever the charges in the cavity
`42 exceed the strength of the dielectric between the
`inlet cavity 42 through the housing 12 to the grounding
`
`This is a divisional of co~pending application Ser. No.
`7/575,260 ?led on Aug. 30, 1990 now US. Pat. No.
`5,076,920.
`-
`This invention relates to a fuel ?lter for use in the fuel
`line that delivers fuel to a motor vehicle engine.
`The housings for ?lters used to ?lter the fuel deliv
`ered to a motor vehicle engine have commonly been
`made of metal or a polymer material, such as Nylon 12.
`Because of their inherently lower cost and other advan
`tages, non-metallic fuel ?lters are preferred. Such non
`metallic fuel ?lters have been commonly used on vehi
`cles having carbureted engines without problems for
`many years. However, when such prior art non-metallic
`fuel ?lters were used on vehicles equipped with elec
`tronic fuel injection (EFI) systems, the non-metallic
`material occasionally broke down and started leaking.
`Since leaking fuel in the hot engine compartment of a
`motor vehicle is extremely dangerous, any leakage from
`a fuel ?lter is unacceptable. Accordingly, metallic ?l
`ters have been used in vehicle equipped with electronic
`fuel injection systems.
`According to the present invention, it has been dis
`covered that the material used in prior art non-metallic
`?lters for electronic fuel injection fuel systems broke
`down and began leaking due to electrostatic buildup
`within the ?lter. Although the generation of electrical
`charges in hydrocarbon systems has been a recognized
`phenomena, it has been of little concern in the past,
`because the metallic components used in prior art sys
`tems provided an electrical path for the electrical
`_ charges to move freely to the grounded vehicle body.
`However, with non-conductive systems in which both
`the tubing and the ?lter are made from a non-conduc
`tive material, the pathway has been removed, leaving
`no way for the charges to drain to ground.
`According to the present invention, a fuel ?lter for a
`motor vehicle is made from a moldable material which
`may be safely used in' vehicles equipped with electronic
`fuel injection system. This and other advantages of the
`present invention will become apparent from, the fol
`lowing description, with reference to the accompany
`ing drawing, the sole Figure of which is a cross-sec
`tional view of a fuel ?lter made pursuant to the teach
`ings of the present invention and its attachment to an
`associated automotive body.
`Referring now to the drawing, a fuel ?lter generally
`indicated by the numeral 10 includes a housing 12
`which is manufactured from a material which is non
`conductive, such as Nylon l2 or another polymer mate
`rial to which a conductive ?ller has been added, as will
`hereinafter be described. The housing 12 is equipped
`with an inlet ?tting 14 and outlet ?tting 16. The inlet
`?tting 14 and outlet ?tting 16 are connected into the fuel
`line which delivers fuel from the fuel tank to the engine.
`The fuel line may also be made of a non-conductive
`material.
`A ?lter element generally indicated by the numeral
`18 is mounted within the housing 12 to ?lter fuel com
`municated through the fuel line. Element 18 includes a
`conventional circumferentially extending array of
`pleated ?lter media generally indicated by the numeral
`65
`20. The pleats forming the ?ltering media 20 de?ne
`outer tips 22 and inner tips 24. A closed end cap 26
`closes the end of the element 18 adjacent to inlet ?tting
`
`55
`
`25
`
`30
`
`35
`
`45
`
`Cisco Systems, Inc., EX 1051 Page 3
`
`

`

`u 5
`
`30
`
`5,164,879
`3
`plane. In this case, the grounding plane is provided by
`the body of the vehicle indicated at 38.
`Although the body of a motor vehicle is commonly
`considered to be “grounded", the grounding is effected
`by connecting the body to the negative terminal of the
`vehicle battery. This provides a grounding plane that is
`slightly positive with respect to an earth ground. Since
`the grounding plane provided by the body 38 is slightly
`positive, the charges in the inlet cavity 42 will be at
`tracted towards the body 38. Accordingly, the charges
`will be concentrated in that part of the cavity 42 closest
`to the body 38. Tests have shown that electrical charges
`move around a curved body, such as the housing 12,
`much more easily than in bodies having other shapes.
`Accordingly, the voltage level of an electrostatic
`charge in that portion of the inlet chamber 42 closest to
`the body 38 may be as high as 8 kV to 10 kV. Since the
`dielectric strength between the cavity 42 and the body
`38 is approximately 7 kV, the dielectric begins to allow
`the charge to pass through the material of the housing
`12 when the voltage level of the electrostatic charge
`exceeds 7 kV. Accordingly, the material of which the
`housing 12 is made is required to absorb a portion of the
`energy associated with the charge. If the charge was
`evenly distributed about the housing 12, the strength of
`the material would exceed the absorption energy during
`25
`the lifetime of the ?lter, but as discussed above, most of
`the charge is concentrated in that part of the cavity 42
`closest to the body 38. When a grounding plane, such as
`the body 38, is within “striking" distance of a charged
`body, the plane itself is a target for electron current
`?ow. The energy which makes up the charge will then
`no longer pass through the body in an evenly distrib
`uted manner. This absorption of energy breaks down
`the material of which the housing 12 is made and results
`in microscopic pin holes in the housing 12. When a large
`concentration of these pin holes occurs in a small area,
`the material comprising the housing 12 breaks down
`and the housing leaks. Tests have shown that the strik
`ing distance is always less than or equal to the radius of
`the curved body.
`40
`According to the present invention, an electrically
`conductive path is provided between the fuel within the
`inlet cavity 42 and the body 38. Accordingly, the elec
`trostatic buildup in the cavity 42 will be discharged
`through the electrically conductive path in bracket 40
`to the body 38, thus avoiding the aforementioned mate
`rial erosion that causes leaks. An electrical path through
`the housing 12 is most easily provided by incorporating
`small amounts of a conductive ?ller material in the base
`Nylon l2 material, thus making the housing electrically
`conductive while substantially retaining the moldability
`and other desirable properties of the polymer material.
`Since the ?ller material must be chemically resistant
`to the fuel in the housing 12, a ?lamentary stainless steel
`?ber product with a high aspect ratio was selected as
`the ?ller material. Stainless steel also has the advantage
`of requiring smaller quantities for providing the re
`quired conductivity than other conductive ?llers, such
`as carbon black, metal ?akes and powders; and metal
`lized microspheres which possess small aspect ratios.
`Stainless steel ?bers used in this application have a pref
`erable upper limit on ?ber diameter of about 8 microns.
`This small diameter, coupled with the low loadings of
`?ller used, allows the matrix to stretch freely between
`and around ?bers as long as the ?ller is properly com
`pounded into the base resin. This reduces dewetting and
`disbonding between the ?ller and base resin, thus pre
`venting cavitation under stress. Stainless steel also pres
`ents itself as a ?ller around which the base Nylon 12
`
`4
`-material bonds to itself. Other electrically conductive
`?llers, such as the aforementioned carbon, act as stress
`concentrators and, at the relatively high ?ller loadings
`required to achieve conductivity, restrict the ability of
`the resin matrix to yield under stress. Also, the stainless
`steel ?bers are ductile and non-rigid unlike straight or
`metallized carbon ?bers or metallized inorganic ?bers
`and whiskers. This allows stainless steel ?bers to main
`tain their integrity better during melt-processing. Un
`like the non-metallic ?bers, stainless steel ?bers also do
`not increase mechanical strength or stiffness of the base
`resin signi?cantly. Other metal ?bers with high aspect
`ratios can be satisfactorily substituted for stainless steel.
`The aspect ratio of the stainless steel ?bers used must
`be large enough to easily conduct electricity at low
`loadings, but small enough to be easily molded with the
`base polymer material into the ?nal part. Accordingly,
`stainless steel ?bers having a diameter of about 8 mi
`crons and a nominal length of from 4-6 mm were se
`lected. Longer steel ?bers can also be used depending
`on design of the ?lter. The longest ?ber length dictated
`by part design and moldability should be used in order
`to minimize ?ller usage. The stainless steel in the com
`posite material is about 3% to 9% by weight, of the
`composite material, which is suf?cient to provide a
`density of about 8 grams of stainless steel ?bers per
`cubic centimeter of material, which provides volume
`and surface resistivities in the 1X 102 to 1X106 range in
`ohm units (surface resistivity) and ohm-cm units (vol
`ume resistivity).
`In order to assure moldability and compatibility be
`tween the stainless steel ?bers and the base Nylon 12
`material, the stainless steel ?bers should preferably be
`coated with small amounts of coupling agents like or
`ganofunctional silane or titanate compounds. Alter
`nately, graft or block copolymers with amide functional
`groups can also be used as coupling agents. Also, small
`amounts of polymers with af?nity for metal surfaces
`and having good compatibility with polyamides can be
`used. These interfacial agents help in wetting and in
`creasing interfacial bonding through formation of mo
`lecular metal-polymer matrix bridges. In addition to
`coupling agents, mold-release agents, internal lubri
`cants, and impact modi?ers can be used to improve
`physical properties of the stainless-?ber ?lled resin.
`We claim:
`1. Fuel system component for communicating fuel to
`the engine of a motor vehicle, said motor vehicle having
`an electrical plane maintained at a predetermined elec
`trical potential, said fuel system component being made
`of a composite material comprising a polymer having
`electrically conductive ?bers distributed randomly
`throughout the material to provide an electrically con
`ductive path through said component between the fuel
`communicated through said component and said elec
`trical plane, so that at least a portion of the electrically
`conductive path extends through the component to
`thereby prevent the build-up of electrostatic charge in
`the fuel and the resultant arcing which causes the break
`down of the polymer material comprising the fuel sys
`tem component.
`2. Fuel system component as claimed in claim 1,
`wherein the ?bers comprise at least 3% to 9% by
`weight of the composite material.
`3. Fuel system component as claimed in claim 2,
`wherein the ?bers are stainless steel ?bers having a
`nominal length of about 4 mm to about 6 mm.
`4. Fuel system component as claimed in claim 3,
`wherein the polymer material is nylon.
`' t i i i
`
`45
`
`65
`
`Cisco Systems, Inc., EX 1051 Page 4
`
`

`

`U SO05 I64879B I
`REEXAMINATION CERTIFICATE (3623rd)
`United States Patent [19]
`[11] B1 5,164,879
`Sep. 8, 1998
`[45] Certi?cate Issued
`Danowski et a1.
`
`[54]
`
`ELECTROSTATICALLY DISSIPATIVE FUEL
`FILTER
`
`[56]
`
`References Cited
`[15. PATENT DOCUMENTS
`
`Dornauf .
`
`Dukek ................................... .. 361/215
`
`Russell ........... ..
`Atterbury et al.
`
`Soens .......... ..
`
`.. 361/215
`264/104
`
`6/1965
`3.186551
`3.929641
`12/1975
`4.196.464
`4/1980
`3/1983
`4,378,322
`5/1987
`4,664,971
`264/104
`Wakita et a1.
`6/1987
`4,675,143
`264/104
`Rosenzweig et a1.
`8/1987
`4.686.071
`3/1989
`4,812,247
`Fahnel' et a1. ......................... .. 264/104
`5,164,879
`11/1992
`Danowski et a1. .
`FOREIGN PATENT DOCUMENTS
`
`Inventors: Daniel R. Danowski. Richmond. R.I.;
`Sunil K. Kesavan. Troy. Mich.: James
`W. Martin; James S. Pereira. both of
`Rehoboth. Mass.
`
`[73]
`
`As signee:
`
`Allied-Signal Inc.. Morris Township.
`Morris County. NJ.
`
`Reexamination Request:
`No. 90/004543. Feb. 7. 1997
`
`Reexamination Certi?cate for:
`Patent No.:
`5,164,879
`Issued:
`Nov. 17, 1992
`Appl. No.:
`724,240
`Filed:
`Jul. 1, 1991
`
`Related US. Application Data
`
`[62] Division of Ser. No. 575,260. Aug. 30, 1990, Pat. No.
`5,076,920.
`
`[51] Im. GL6 ................................................... .. B01D 27/08
`[52] US. Cl. ............. ..
`361/215; 210/243; 210/743
`[58] Field of Search ................................... .. 210/243. 446.
`210/4935. 748; 361/215. 212; 252/511.
`518. 519; 428/364‘, 264/105
`
`Japan .
`Japan .
`
`France .
`
`France .
`
`10/1968
`1541025
`10/1969
`1541025
`1/ 1986
`A-61-8102
`4/1988
`U-63-54859
`7/ 1995
`U-50-77878
`Japan .
`Primary Examiner—Neil McCarthy
`ABSTRACT
`[57]
`A fuel system component for a motor vehicle constructed
`from a polymer material to which are added stainless steel
`?bers to render the component electrically conductive while
`retaining rnoldability. The electrically conductive compo
`nent permits charges generated by the fuel passing through
`the component to be dissipated to the vehicle body. thereby
`preventing arcing which causes erosion of the component
`and subsequent leaks.
`
`.TIIIIIIIIIIIIIII
`
`42 36 24 I8 28
`
`Cisco Systems, Inc., EX 1051 Page 5
`
`

`

`Bl 5.164.879
`
`1
`REEXAMINATION CERTIFICATE
`ISSUED UNDER 35 U.S.C. 307
`
`THE PATENT IS HEREBY AMENDED AS
`INDICATED BELOW.
`
`Matter enclosed in heavy brackets [ ] appeared in the
`patent, but has been deleted and is no longer a part of the
`patent; matter printed in italics indicates additions made
`to the patent.
`
`10
`
`AS A RESULT OF REEXAMINATION. IT HAS BEEN
`DETERMINED THAT:
`
`Claim 1 is determined to be patentable as amended.
`
`15
`
`Claims 2-4. dependent on an amended claim. are deter
`mined to be patentable.
`
`New claims 5-9 are added and determined to be patent
`able.
`
`1. [Fuel] A fuel injection system component for commu
`nicating fuel to the engine of a motor vehicle. said motor
`vehicle having an electrical plane maintained at a predeter
`mined electn'cal potential. said fuel injection system com
`ponent being made of a composite material comprising a
`polymer having electrically conductive ?bers distributed
`randomly throughout the material to provide an electrically
`conductive path through said component between the fuel
`communicated through said component and said electrical
`plane. so that at least a portion of the electrically conductive
`path extends through the component and a conductive
`member leading to said electrical plane to thereby prevent
`the build-up of electrostatic charge in the fuel and the
`
`25
`
`30
`
`2
`resultant arcing which causes the breakdown of the polymer
`material comprising the fuel injection system component.
`5. A fuel injection system component for communcating
`fuel to the engine of a motor vehicle, said motor vehicle
`having an electrical plane maintained at a predetermined
`electrical potential, said fuel injection system component
`comprising:
`a composite material forming a fuel ?ow path, said
`composite material including a polymer having elec
`trically conductive ?bers distributed randomly
`throughout the material to provide an electrically con
`ductive path through the component between the fuel
`communicated through the component and the electri
`cal plane; and
`conductive means forming part of the electrically con
`ductive path from said composite material to the elec
`trical plane, with at least a portion of the electrically
`conductive path extending through the component and
`said conductive means to thereby prevent the build-up
`of electrostatic charge in the fuel and the resultant
`arcing which causes the breakdown of the polymer
`material comprising the fuel system component.
`6. A fuel injection system component as claimed in claim
`5, wherein the ?bers comprise at least 3% to 9% by weight
`of the composite material.
`7. A fuel injection system component as claimed in claim
`6, wherein the ?bers are stainless steel ?bers.
`8. A fuel injection system component as claimed in claim
`6, wherein the ?bers having a nominal length of about 4 mm
`to about 6 mm.
`9. A fuel injection system component as claimed in claim
`8, wherein the polymer material is nylon.
`
`*
`
`* * *
`
`*
`
`Cisco Systems, Inc., EX 1051 Page 6
`
`