In-tank fuel pump and reservoir

An engine fuel delivery system and method, and for use therein, an in-tank fuel pump and reservoir canister module assembly having a primary fuel filter mounted in a base subassembly adjacent the bottom of the tank and defining a filter chamber in the base having an outlet connected to the inlet of an electric fuel pump received directly in the tank exteriorly alongside of an upright open top reserve fuel canister. The pump outlet is connected to a bypass pressure regulator which discharges fuel in excess of engine demand into the canister. The canister has a bottom outlet mounted on the base subassembly and closed by a flow controlling valve and/or by a restricted orifice communicating the canister outlet with the filter chamber for returning bypassed reserve fuel from the canister reservoir to the pump inlet, either continuously and/or when a low level supply of fuel in the tank to the primary filter is interrupted, such as during cornering or going up or down a steep hill or incline. The valve is formed integrally on or mounted in contact with a secondary filter diaphragm base mounted between the canister outlet and filter chamber and also communicating with the tank. The valve opens with canister outflow downwardly against the bias of a coil spring in response to pump suction acting on a capillary seal formed on the diaphragm filter material to thereby allow reserve fuel to wash over and flow through it into the filter chamber. At system shut-down a filter backwash flow can occur from the canister reservoir.

FIELD OF THE INVENTION 
This invention relates to vehicle fuel systems and more particularly to an 
electric fuel pump and reservoir disposed in a main fuel tank of a 
vehicle. 
BACKGROUND OF THE INVENTION 
Modern fuel delivery systems for automotive vehicles with engines having 
fuel injectors have utilized an electrically driven fuel pump in the 
vehicle main fuel tank. Typically, the electric fuel pump is mounted 
either directly in the vehicle tank, or is mounted within a reservoir 
canister received in the tank as shown for example in U.S. Pat. Nos. 
4,747,388; 4,807,582; 4,831,990; 4,893,647; and 4,964,787. The canister 
reservoir supplies fuel to the pump in the event there is an interruption 
in the availability of fuel from the tank, such as when, under low fuel 
level conditions, cornering of the vehicle causes sloshing or movement of 
the fuel away from the pump inlet and to one side or the other of the 
tank, and/or when the tank is excessively tilted by vehicle inclination on 
severe grades, or when essentially all of the fuel in the main tank has 
been consumed or used. Typically, the output of the fuel pump is greater 
than that required by the vehicle engine and the excess fuel is either 
returned from the fuel injectors to the tank or to the in-tank canister 
reservoir. 
Typically, in a no-return fuel system, there is only one fuel supply line 
between the fuel pump module and an engine fuel rail or manifold 
distributing fuel to the individual fuel injectors, and downstream of the 
fuel injectors there is no line returning unused fuel from the rail or 
manifold to the fuel tank. In such non-return fuel systems excess fuel is 
bypassed directly to the tank or canister reservoir, typically by a 
pressure regulator usually located closely downstream of the pump outlet 
within the tank or canister, or by a return line to the tank or canister 
when the regulator is exteriorly remote from the tank. 
In the aforementioned fuel systems in which the fuel pump is mounted in a 
fuel canister special valving has been provided between the canister, 
reservoir and the pump inlet to supply reserve fuel when the main tank 
supply is low; see for example the above cited U.S. Pat. No. 4,747,388. In 
this system, a valve actuated by pump suction lift of the primary fuel 
filter opens to provide fuel from the canister reservoir to the pump inlet 
when the pump inlet is starved because of low fuel or because of movement 
of fuel in the main tank to one side or the other during vehicle 
negotiation of a curve in the road. Further examples of use of a reservoir 
canister and special valving for supplying reserve fuel to a fuel pump are 
disclosed in U.S. Pat. Nos. 4,546,750 and 5,237,977. In these systems, 
under conditions of low fuel in the main fuel tank a valve associated with 
the canister responds to inertial forces created by side swerving motion 
of the vehicle, and/or in response to gravitational forces caused by 
excessive tilting of the vehicle on hills and grades, to open and allow 
flow of fuel from the canister to the fuel flow passage leading to the 
pump to thereby prevent starving of the engine due to no or low pump 
inflow from the main fuel tank. 
Another system in accordance with the present invention for preventing 
starving of the fuel pump and hence the engine due to low flow from the 
main tank is that set forth in co-pending benefit parent application Ser. 
No. 08/496,950, filed Jun. 30, 1995 in the name of Charles H. Tuckey and 
assigned to Walbro Corporation, which is incorporated herein by reference. 
In this system a fuel pump is mounted directly in the tank and an in-tank 
standpipe reservoir is also mounted in the tank alongside of the pump and 
receives bypass fuel from the pump. A restricted orifice provides the 
standpipe outlet and feeds into the space above the filter media of the 
primary fuel filter to thereby provide an always-open reserve fuel flow 
path from the standpipe reservoir to the fuel pump inlet. The orifice is 
calibrated to be balanced with pump draw to prevent standpipe overflow so 
most if not all bypass fuel is returned to the pump inlet rather than 
overflowing to the main tank. This system also enables the reservoir fuel 
at pump shut down to gravity flow back into the main tank from the 
interior of the main filter under low tank fuel level conditions to 
thereby backflush contaminants from the exterior surface of the main 
filter. 
Generally speaking two types of electrically driven rotary fuel pumps have 
hitherto been used in the vehicle main fuel tank for pumping liquid fuels 
to the fuel injectors of the automotive vehicle engine, namely a turbine 
type vane pump or a positive displacement pump. One preferred form of a 
positive displacement gear rotor type electric fuel pump is disclosed in 
U.S. Pat. No. 4,697,995, and a suitable turbine regenerative fuel pump is 
disclosed in U.S. Pat. No. 5,257,916, the disclosures of which are 
incorporated herein by reference. 
In-tank vehicle fuel pumps must be capable of operating in a wide range of 
ambient temperatures. The hydrocarbon fuels (gasoline and alcohol) have a 
relatively low boiling point. In certain geographical areas, the ambient 
temperatures may reach 110.degree. to 120.degree. Fahrenheit. The 
temperature in the fuel tank below the automotive vehicle may be even 
higher than this. Since these pumps are frequently mounted in the fuel 
tanks, there is a great likelihood that the fuel in the pump may vaporize. 
The pumps when mounted in reservoir canisters are usually positive 
displacement pumps and it is necessary that the entry to the pump chambers 
create a low pressure to draw fuel into the pumping chambers. This reduced 
pressure alone may cause a change in state of the fuel from liquid to 
vapor at elevated temperatures and significantly reduce the efficiency of 
the pump. 
In another condition as, for example, when a vehicle has been operating and 
then the engine shut off for a period, the fuel line between the pump and 
fuel injectors full of liquid fuel under pressure whereas the fuel in the 
pump can be completely vaporized due to the elevated temperature in the 
fuel tank and pump itself. Thus, when the engine is restarted, the pump is 
full of vapor and even the fuel in the entrance filter may be vaporized. 
The pump cannot, under these conditions, generate enough pressure to move 
the fuel in the pressurized fuel supply line. 
Accordingly, both of the aforementioned U.S. Pat. Nos. 4,697,995 and 
5,257,916 patents disclose a rotary pump construction with a built-in 
vapor purging system which will enable the pump to operate under the 
conditions above described without interruption of the fuel supply, with 
one major exception. In accordance with the present invention it has been 
found that turbine vane pump when disposed within an in-tank canister 
reservoir does not operate satisfactorily to sufficiently purge itself of 
vapor under adverse temperature or other vapor-inducing conditions. Due to 
the preferred location and size of the vapor purge port in the first or 
pre-channel zone and the inherent operating characteristics of the turbine 
pump, only a small amount of vapor pressure build up can be produced by 
such a pump at the pump vapor purge port. Hence, unlike the positive 
displacement pumps employed within the in-tank canister reservoirs as 
described previously, it has been found that such a vane type pump cannot 
purge itself of vapor in the pumping channel if the pressure differential 
between the pump inlet and the vapor port outlet exceeds about 21/2 inches 
of water. 
This constraint as to self-purging of vapor does not apply to positive 
displacement gear rotor pumps of the aforementioned type since they 
characteristically pump both fuel vapor and air very well. Hence, when 
mounted inside an in-tank fuel reservoir canister and provided with a 
vapor purging port communicating with the column of fuel in the canister 
and located at approximately the elevation of the rotary pump chamber, 
such positive displacement pumps can purge vapor into the canister against 
a gravity fuel differential pressure head ranging from say six on up to 
ten or twelve inches, as when the canister reservoir is full and the 
gravity head at the pump inlet exerted by the body of fuel in the tank 
exterior to the canister reservoir is very low. 
Nevertheless, some OEM automotive vehicle manufacturers have preferred 
turbine vane fuel pumps for use in fuel tanks over gear rotor positive 
displacement pumps for a variety of reasons, even though they have had to 
forsake the advantages of a canister reservoir-type reserve supply of fuel 
for preventing starvation of fuel supply to the turbine pump from the main 
tank in order to obtain vapor self-purging operation. In an attempt to 
make up for this lack of the preferred selectable alternative canister 
reserve supply of fuel, such as that provided in the aforementioned U.S. 
Pat. No. 4,747,388, some automotive manufacturers have mounted turbine 
vane fuel pumps in specially configured fuel tanks with the pump inlet 
submerged in a so-called "swirl pot", i.e., a molded-in basin in the tank 
bottom in an attempt to maintain an adequate body of fuel in the vicinity 
of the fuel pump inlet to prevent pump starvation. However such swirl pots 
are still subject to being emptied by severe vehicle cornering or 
excessive vehicle inclination, as well as when essentially all of the fuel 
of the main tank has been consumed or used. Such swirl pots also 
inherently must be limited in their length, width and depth dimensions, 
thereby imposing a further constraint on the bulk of the fuel pump and 
associated filter package which can be accommodated in such swirl pots. 
Despite such hitherto prevailing limitations, some OEM automotive vehicle 
manufacturers have preferred to use turbine vane-type fuel pumps over gear 
rotor positive displacement pumps for in-tank mounting because such 
turbine vane pumps generally are quieter and smoother running, and also 
have low tank fuel level operation performance characteristics preferred 
by such vehicle manufacturers over those of gear rotor positive 
displacement pumps. With a typical positive displacement gear rotor fuel 
pump, such as that disclosed in the aforementioned U.S. Pat. No. 
5,257,916, when the pump encounters like conditions with a large presence 
of vapor in the pump chamber, the positive displacement pump will continue 
to pump liquid fuel but will also pump vapor as well. When this condition 
occurs the fuel pumped to the engine contains vapor and/or air entrained 
with liquid fuel. This will cause the vehicle engine to spit and stumble 
or otherwise run rough even though the engine continues to run on this 
vapor and liquid fuel mixture. However, because of constraints imposed by 
engine control unit (ECU) operational characteristics and exhaust emission 
requirements, several vehicle manufacturers would prefer to see the 
instantaneous shut off characteristic under extreme low tank fuel level 
conditions of the turbine vane fuel pump, wherein the pump ceases pumping 
any fuel. 
OBJECTS OF THE INVENTION 
Accordingly an object of the present invention is to provide an in-tank 
fuel delivery system, method and module which solves the aforementioned 
problem of the existing trade-off hitherto required between utilizing a 
positive displacement pump housed in a reservoir canister, and thereby 
provided with an ample supply of reserve fuel under all tank fuel level 
conditions, versus a turbine vane type fuel pump having preferred 
performance characteristics and operable vapor purging system but lacking 
an adequate and selectable reserve body of fuel to prevent pump starvation 
under adverse tank fuel level conditions. 
A further object of the invention is to provide a fuel delivery in-tank, 
system, method and module of the aforementioned character embodying both 
an in-tank fuel pump and a canister reservoir of the "bottom seeking type" 
which can be made in a compact subassembly small enough to fit within the 
existing confines of a fuel tank swirl pot and in which the fuel pump 
inlet can selectively draw from the main tank fuel body or the reserve 
body of fuel in the canister, and with the canister reservoir fuel reserve 
being maintained in a non-overflow state with bypass fuel return under 
normal operating conditions so that all of the advantages of in-tank 
canister reservoirs are obtained as well as all of the advantages of 
turbine vane fuel pump performance, while also enhancing the 
self-vapor-purging capability of the vapor purging system built into the 
pump and insuring return of twice-filtered bypass fuel to the pump inlet 
in preference to overflow return to the fuel tank. 
Yet another object of the present invention is to provide a fuel delivery 
system of the aforementioned character in which the canister reservoir can 
be made in varying sizes and capacities as permitted by the vehicle tank 
configuration, while also being capable in some embodiments of utilizing 
existing canister reservoir diaphragm operated bottom outlet valves or, 
alternatively, utilizing improved canister outlet fuel flow control 
systems and constructions of the invention for preventing fuel starvation 
of the pump inlet and operable at pump shut down to backflush contaminants 
from the exterior of the main filter. 
Additional objects, features and advantages of this invention are to 
provide a vehicle in-tank fuel delivery module of the aforementioned 
character with the fuel pump mounted directly in the main body of fuel in 
vehicle fuel tank and in which an associated in-tank canister reservoir 
supplies fuel to the pump through the interior of a main pump inlet filter 
when the flow of fuel from the main tank is interrupted, the fuel supplied 
during interruption is twice filtered, admission of air and fuel vapor to 
the pump inlet is inhibited during interruption of the supply of fuel from 
the tank, and the canister and pump assembly is compact, rugged, durable, 
reliable, of relatively simple design, economical manufacture and 
assembly, and in service has a long useful life. 
SUMMARY OF THE INVENTION 
In general, and by way of summary description and not by way of limitation, 
the foregoing objects are achieved by providing in accordance with the 
invention an electric fuel pump, preferably turbine vane type having a 
vapor purge system, mounted in bottom-seeking manner directly in the main 
body of liquid fuel in a vehicle fuel tank with a fuel inlet connected to 
the tank fuel via main fuel filter chamber disposed in the bottom of the 
tank, such as in a swirl pot basin. A fuel outlet of the pump supplies 
fuel for a vehicle engine and also communicates through a bypass, such as 
a pressure regulator, with an open-top in-tank reservoir canister mounted 
in a compact manner laterally adjacent the pump. The canister accumulates 
a reserve of filtered and bypassed fuel therein, and preferably adjacent 
its bottom communicates through a calibrated orifice, and in one 
embodiment also through a diaphragm actuated valve, and a secondary filter 
with the main filter chamber to maximize return of bypass fuel to the pump 
inlet and to provide an auxiliary supply of fuel to the pump inlet when 
there is an interruption of fuel from the tank to the filter. 
In one embodiment the second filter overlies the orifice and is located in 
the reservoir canister so that bypassed reserve fuel is twice filtered. In 
another embodiment the secondary filter is located beneath the reservoir 
outlet so that bypassed reserve fuel is again filtered on its return path 
to the pump inlet, and communicates with both the reservoir outlet and 
main fuel tank to provide a secondary in-take flow path from main tank to 
pump inlet in parallel with the main filter. In both embodiments the 
secondary filter communicates, directly or indirectly, with the interior 
of the fuel tank to permit any vapor in the fuel to be separated by the 
secondary filter and except to the tank headspace. When the canister 
overflows, excess bypassed fuel is discharged through the open top of the 
canister into the tank. 
Preferably, both the main and secondary filters are made of a mesh plastic 
material, such as a woven fabric, having openings with an average size not 
greater than about 100 microns through which liquid fuel will pass when 
the material is immersed in fuel, and if wet with fuel when exposed to air 
will resist and prevent the flow of air through the filter material due to 
capillary action of the wetted filter material. Thus, when the supply of 
fuel from the tank to the filter is temporarily interrupted, the pump 
draws additional bypass fuel from the reservoir through the canister 
outlet and the interior of the main filter chamber into the pump inlet. A 
baffle is received in an envelope of the main filter material or a 
perforate retainer overlies a single ply of main filter material to 
prevent the filter material from restricting or closing off the flow of 
fuel from the canister orifice to the pump inlet when the fuel supply from 
the tank is temporarily interrupted. The interior of the main filter 
chamber also provides a partial reservoir of fuel to be supplied to the 
pump inlet when the supply of fuel from the tank is temporarily 
interrupted. 
Preferably, the fuel pump is a turbine vane type provided with a built-in 
vapor purging system having a vapor purge inlet communicating with the low 
pressure zone of the rotary pump chamber and a vapor purge outlet leading 
to the exterior of the pump casing generally at or slightly above the 
elevation of the pump fuel inlet. Because the pump is mounted directly in 
the main body of liquid fuel in the tank, outside the reservoir canister, 
the pump inlet and pump vapor port outlet are both exposed to the 
substantially the same gravity pressure head being exerted by the main 
body of fuel in the tank. Therefore the head of fuel in the canister 
reservoir, regardless of its magnitude, will not impede or impair self 
purging of vapor by the pump. 
In another embodiment of the invention the canister reservoir is enlarged 
in capacity without increasing overall base dimensions, to provide a 
reserve capacity similar to typical fuel sender modules having reservoir 
canisters containing fuel pumps therein. A "switchover" and bypass return 
regulator structure is provided at the bottom of the canister comprising a 
bottom septum partially or fully closed by a movable valve. A diaphragm 
made of filter material extends over this canister valve to filter reserve 
and/or tank fuel entering the pump inlet via the main filter chamber and 
to operate the reserve supply valve to regulate return of bypassed reserve 
fuel to the pump, the valve being moved fully open under fuel starvation 
conditions and high pump demand. A bottom base subassembly containing the 
secondary filter diaphragm valve and main filter supports the canister and 
fuel pump and communicates the pump inlet with the main body of the fuel 
in the tank downstream of both the main and secondary filters. The 
secondary filter acts as a diaphragm type canister bottom outlet valve and 
is mechanically associated centrally with a biasing spring that normally 
biases the secondary filter diaphragm valve closed. The diaphragm valve is 
alternately provided either with an always-open orifice controlling bypass 
reserve fuel return or is completely sealed to achieve complete shut off 
bypassed fuel return flow from the canister bottom outlet. With both forms 
of diaphragm valve, and under conditions where the bottom of the main 
filter chamber is starved of liquid fuel from the main tank body of fuel, 
the secondary filter acts in response to pump suction as a diaphragm to 
shift against the resilient bias of the spring and variably open the 
canister bottom outlet to admit reservoir fuel from the canister to the 
pump inlet to thereby either augment or to initiate bypass fuel return to 
the pump. 
At pump shut down, the calibrated orifice embodiments cooperate with 
whatever gravity head differential is available to act on bypass reserve 
fuel in the canister to backwash at least the main filter, and in the 
diaphragm valve embodiment, also the secondary filter. In the latter case, 
the secondary filter is disposed at a higher elevation than the main 
filter and provides a parallel intake flow path to the pump inlet from the 
main tank to thus provide a fail-safe feature in the event of main filter 
clogging.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
First Embodiment 
FIG. 1 illustrates a first embodiment of a fuel pump module assembly 10 
embodying this invention mounted in a fuel tank 12 of a vehicle, such as 
an automobile, for supplying liquid hydrocarbon fuel, such as gasoline, to 
a vehicle engine which is typically fuel injected. The assembly has an 
electric fuel pump 14 with an inlet 16 connected to a primary or main fuel 
filter 18 and an outlet 20 connected to a bypass regulator 22 which 
regulates the pressure of fuel supplied to the engine through a conduit 
24. A fuel reservoir canister 26 is connected adjacent its upper end to 
the bypassed fuel outlet 28 of the regulator 22 and at its lower end to 
the interior of filter 18 through an orifice plate 30. 
The fuel pump 14 has a pump assembly 32 (FIG. 1) driven by an electric 
motor 34 both of which are sealed in a cylindrical housing 36 with a 
bottom inlet end cap 38 and top outlet end cap 40 (see also FIG. 2). The 
pump 32 is preferably a turbine type pump but alternatively it may be a 
positive displacement type pump. A suitable positive displacement gear 
rotor type electric fuel pump is disclosed in U.S. Pat. No. 4,697,995, and 
a suitable turbine regenerative fuel pump is shown in U.S. Pat. No. 
5,257,916, the disclosures of which are incorporated herein by reference 
and hence the pump 14 will not be described in further detail. However, it 
is to be noted that each of these patents disclose rotary pumps with a 
built-in vapor purging system to allow purging of vapor from the pump to 
enable the pump to be self-priming and to pump against a pressurized fuel 
line under hot fuel conditions. 
Referring more particularly to the gear rotor pump of the '995 patent, and 
parenthetically using the reference numerals appearing therein, the vapor 
purging is accomplished by providing a passage (110) opening to the 
interface of the inlet housing (FIGS. 1 and 4) and angling at (112) to the 
outer surface of the circular wall (100) forming the lower end cap of the 
pump. A small hole is punched in the flexible plate (60) provided in this 
pump in order to register with the passage (110). A small pocket (114) is 
provided in the radial face of the inlet housing to prevent possible 
blocking of the purged passage outlet (112) by a filter connector mounted 
on the inlet housing (10). Note that purge vapor outlet pocket (114) is 
generally at the elevation of the pump inlet port (90). Purge port (110) 
allows vapor in the pumping chamber to escape to the fuel tank early in 
the compressive stage of the pump rotation so that the intake port of the 
pump can draw fuel in, thus to facilitate priming. Accordingly, the pump 
can develop normal operating pressure to prime, when starting initially, 
and overcome the stored pressure in the fuel line upon restart. This 
facilitates quick priming to obtain the required pumping pressure on hot 
fuel which is subject to vaporization. 
Similarly, and referring now to the turbine regenerative fuel pump 20 of 
the aforementioned '916 patent, and again parenthetically using the 
reference numerals appearing therein, a vapor port (72) opens into the 
upstream region of the pumping channel (62) immediately adjacent the 
downstream region. In particular, vapor port (72) opens to channel section 
(62) adjacent to the leading edge of the grooves (70), i.e., at the edge 
of the groove array proximate to pump inlet port (56). Again, it is to be 
noted that the lower end cap side plate (26) of pump (20) is provided with 
the vapor port (72) and hence port (72) leads to the exterior of the lower 
end of the pump through the end plate and is generally at the elevation of 
pump inlet (58). 
Thus in the electric motor-pump assembly 14 of FIGS. 1 and 2 herein, the 
rotary pump 32 of the assembly is shown diagrammatically with a pumping 
chamber 33 (shown with broken lines) and associated vapor purge port 
passage 35 (also shown in broken lines) leading from pump chamber 33 down 
through end cap 38 to an outlet communicating directly with the interior 
of tank 12. Purge outlet 35 is disposed slightly above the elevation of 
the pump inlet 16 which in turn also communicates directly with the 
interior of the tank (through primary filter 18). Vapor port passage 35 
thus corresponds to passage 110, 112 in the '995 patent and to vapor port 
72 of the 916 patent, and functions in similar but enhanced manner in 
accordance with a further feature of the present invention because of the 
manner in which pump assembly 14 is exteriorly associated with the fuel 
reservoir canister 26 in accordance with the invention. 
In normal operation, the pump 14 operates at constant speed and supplies a 
greater quantity of fuel to the pressure regulator 22 than is needed even 
to meet the maximum demand of the operating engine. Regulator 22 maintains 
a substantially constant pressure of fuel supplied through its outlet 42 
to the engine by bypassing or discharging excess fuel through its bypass 
outlet 28 into the reserve fuel reservoir of canister 26 and at a variable 
flow rate inverse to that flowing in line 24 to the engine. Typically, the 
pressure regulator has a flow rate control valve actuated by a diaphragm 
in response to changing fuel demand of the engine to maintain a 
substantially constant output pressure. Typically, the regulator will 
maintain a substantially constant output pressure, such as 50 psig, with a 
pressure drop of about 1 psi over the full range of variation of the fuel 
flow rate to the engine from 0 to 40 gallons per hour. Preferably, the 
fuel pump assembly 10 is used in a no-return fuel system which does not 
have any line returning fuel from the downstream side of the engine fuel 
injectors or the fuel rail to the fuel tank. Suitable pressure regulators 
22 for no-return fuel systems are disclosed in U.S. Pat. Nos. 5,220,941 
and 5,398,655, the disclosures of which are incorporated herein by 
reference and hence the pressure regulator 22 will not be described in 
greater detail. 
The primary filter 18 has a bag or envelope 50 formed from a sheet 52 of a 
flexible filter material of a fine mesh, such as a plastic material, which 
is heat sealed together around its periphery 54. The interior chamber 56 
of the envelope communicates through an outlet 58 with the inlet 16 of the 
pump into which it is slidably received and frictionally retained with an 
interference fit. Preferably, the outlet 58 is made of a plastic material 
and has a peripheral flange 60 secured and sealed by a heat seal 62 to the 
upper wall 64 of the sheet filter material 52. Preferably, a 
fuel-permeable spacer, such as a flexible corrugated baffle 66, which can 
be made of a resilient plastic material, is received in the envelope 50 to 
prevent the flexible bottom wall 68 of the filter material 52 from 
collapsing under the weight of the pump assembly, and from being forced 
upwardly by pump suction onto the outlet 58 in the upper wall 64 and 
thereby restricting flow of fuel through the outlet and into the pump 
inlet 16. As best seen in FIG. 1, the baffle 16 is narrower in width than 
envelope 18 to thereby enable free flow of fuel within the envelope around 
the side edges of the baffle so that the baffle can be made of imperforate 
material, if desired. In use, the filter 18 and the pump inlet 16 lie 
closely adjacent to the bottom of the fuel tank 12, and preferably the 
bottom wall 68 of the fuel filter lies on the bottom wall 70 of the 
lowermost portion of the fuel tank (e.g., within a tank swirl pot). For 
this purpose module assembly 10 is preferably vertically movably supported 
from a conventional tank top mounting flange (not shown) on a suitable 
conventional telescopic type support fixture (not shown) so as to be 
gravitationally biased, and also, if desired, spring biased and 
pressurized outlet hose biased, downwardly as a "bottom-seeking" type fuel 
sender module. 
Preferably, reservoir canister 26 is formed by a tube 80, preferably made 
of a fuel-compatible plastic material such as Acetal, with a peripheral 
flange 82 at its lower end which overlies an opening 84 through the upper 
wall 64 of the filter material and is attached and sealed to it by a heat 
seal 86. The underlying orifice plate 30 is also secured and sealed to the 
flange and the adjoining filter wall by a heat seal 88 to close the bottom 
of the reservoir tube 80 so that fuel will flow from the bottom of the 
reservoir only through a calibrated orifice 90 in the plate. The orifice 
90 is sized so that the reservoir tube 80 will be substantially completely 
filled with fuel discharged from the bypass outlet 28 of the pressure 
regulator 22 during normal operation of the pump. For fuel pumps having an 
output capacity under normal operating pressure conditions of up to about 
40 gallons per hour, the orifice 90 typically has a diameter in the range 
of about 0.10 to 0.20 of an inch. In other words, the flow controlling 
cross section of orifice 90 is thus correlated with pump output and engine 
fuel demand parameters to obtain a reserve fuel flow "balance" between 
bypass fuel input to canister 26, and reserve fuel canister outflow via 
orifice 90 and back through main filter chamber 56 to the pump inlet 16, 
to establish a maximum gravity reserve head of fuel in the canister with 
minimum, if any, overflow from the open top of canister 26 back into the 
main tank. 
Preferably, to further filter fuel supplied from the reservoir 26, a 
secondary filter 92 is disposed in the bottom of the tube 80 and overlying 
the orifice 90. Preferably, filter 92 has a finer mesh or openings size 
than the primary filter 18 and typically has an opening average size not 
greater than about 60 microns. Preferably, the secondary filter has an 
average opening or pore size of about 30 to 40 microns and the primary 
filter has an average opening or pore size of about 60 to 70 microns. To 
insure that any air or gaseous vapor in the liquid reserve fuel does not 
block or restrict the flow through the orifice 90, the filter 92 is 
disposed above the orifice rather than below it so vapor can indirectly 
escape to the tank headspace upwardly through the body reserve fuel in the 
canister. In use, the baffle 66 also insures that the flexible bottom wall 
68 of the filter material is not forced or collapsed onto the orifice 90 
which would block the flow of reserve fuel down through the orifice and 
via the interior chamber 56 of the filter to the pump inlet 16. 
Adjacent the upper end of reservoir tube 80, a cylindrical portion 94 of 
the housing 96 of the pressure regulator 22 projects through a bore 98 in 
the sidewall of the tube 80. A peripheral annular flange 100 is pressed 
with an interference fit into a collar 102 coaxial with and encircling the 
bore and integral with the tube. Preferably, an O-ring 104 provides a seal 
between the regulator housing 96 and the tube 80. The upper end 106 of the 
reservoir tube 80 opens into the fuel tank headspace and thus prevents any 
pressure build-up from bypass fuel flow input that would occur if the 
canister top were sealed, and thus permits excess reserve bypass fuel to 
flow out of the top of the reservoir tube into the fuel tank. The open-top 
canister also permits any air or vapor in the fuel in the reservoir tube 
to rise and separate from the reserve fuel and pass through the open end 
106 into the vapor dome headspace in the fuel tank. 
In use, the fuel pump module 10 is mounted in the fuel tank with the 
reservoir canister tube 80 extending generally vertically and the fuel 
filter 18 immediately adjacent the lowermost bottom portion 70 of the fuel 
tank and preferably resting on the bottom 70 of the tank as a 
"bottom-seeking" module. In fuel tanks provided with a molded-in or 
stamped-in "swirl pot" in the lowermost region of the tank (see FIG. 3), 
the relatively compact lateral dimensions of module 10 with its elongate 
filter 18 enable the same to fit within the sometimes narrow confines of 
such a swirl pot. In normal use, the fuel tank is at least partially full 
of a liquid fuel, such as gasoline, to a level above the filter 18 so that 
the filter and the pump inlet 16 are completely immersed in fuel. 
In normal operation of the electric fuel pump 14, fuel is drawn from the 
main body of fuel in the tank through the filter 18 into the inlet 16 of 
the pump and discharged from the outlet 20 of the pump into the inlet of 
the pressure regulator 22 which supplies through its outlet 42 fuel to the 
engine at a substantially constant pressure, such as 50 psig and at a 
variable flow rate established by variable engine fuel demand. Regulator 
22 maintains a substantially constant output pressure by bypassing a 
portion of the fuel supplied to its inlet and discharges the bypassed fuel 
through its bypass outlet 44 into the reservoir canister 26. In normal 
operation of the pump, due to the aforementioned canister reserve fuel 
head balance with calibrated orifice 90, fuel in the reservoir tube 80 
rises to a level which is usually adjacent to or above the bypass outlet 
28. In some normal operating conditions, such as extended periods of the 
engine idling or operating under a low load, the fuel level can rise to 
the top of tube 80 and overflow into the tank through the open upper end 
106 of the tube. Thus, in normal operation, some of the fuel entering the 
reservoir also flows continuously out of the bottom of the tube through 
the secondary filter 92 and calibrated orifice 90, passes through the 
interior chamber 56 of the primary filter 18 and reenters the pump inlet 
16 along with fuel drawn from the tank through the primary filter. 
Preferably, the maximum canister head reserve fuel level is maintained 
below canister overflow level so that as much as possible of the bypassed 
fuel, which has already been once filtered by passing through filter 18 to 
the pump inlet, is returned to the pump inlet after being again filtered 
through the secondary filter 92. This reduces the overall or average rate 
of fuel draw from tank 12 through filter 18 and hence reduces the rate of 
tank contaminant clogging of filter 18. It also maximizes the amount of 
twice-filtered fuel delivered to the engine. 
When the fuel level in the tank becomes low enough, during normal operation 
of the vehicle, such as when turning corners or going up and down, or 
while parked on, a steep hill or incline, the remaining fuel in the tank 
will move away from the primary filter 18, thereby momentarily 
interrupting ("starving") the supply of fuel from the tank through the 
filter to the inlet 16 of the pump. During these fuel interruptions, the 
pump receives fuel from the reserve supply in reservoir canister 26 at a 
greater flow rate than when tank fuel is available at filter 18 due to the 
increase in negative pressure at orifice 90 exerted by pump suction under 
these adverse conditions. The reserve fuel thus flows through the 
secondary filter 92, calibrated orifice 90, interior chamber 56 of filter 
18 and into the inlet 16 of the fuel pump at a sufficient rate to satisfy 
pump and engine fuel demand and thereby avoid fuel starvation interruption 
under such adverse conditions. Meanwhile, fuel in excess of engine demand 
continues to be returned into tube 80 from bypass regulator 22 to thereby 
prolong the availability of reserve fuel during such adverse conditions. 
During the "starvation" interruption of fuel from the tank, the capillary 
action of the wet sheet of filter material 52 forming top and bottom 
envelope walls 64 and 68 prevents air and fuel vapor from passing through 
the filter material into the interior chamber 56 of the filter bag or 
envelope 50 and into the pump inlet. If the interruption of the fuel in 
the tank is of sufficient duration so that all of the reserve fuel in the 
reservoir canister 26 is consumed, then the filter envelope chamber 56 
itself provides an additional reservoir or reserve of fuel which is 
supplied to the pump. Preferably, as this fuel is depleted, the walls 64 
and 68 of the flexible filter material 52 collapse inwardly, but the 
baffle 66 prevents the filter material from restricting or closing off the 
pump inlet 16. This also insures that the filter material continues to be 
wetted by the remaining small quantity of fuel so that air and fuel vapor 
do not enter the pump inlet 16 until essentially all of the fuel has been 
consumed. The baffle also insures that when an essentially completely 
empty fuel tank is refilled, the walls of the filter 18 will be expanded 
into their normal operating position, thereby insuring that the inlet 16 
of the fuel pump will be unrestricted when the engine is restarted. 
It will also now be apparent from the foregoing description and drawings 
that, under normal operating conditions, tube 80 will normally be almost 
if not completely full of reserve fuel at engine shut-down. Although the 
reserve fuel during such engine-off periods can drain from tube 80 via 
calibrated orifice 90 and filter 18 and thus leak back into the main body 
of fuel in tank 12, this leakage will occur only to the extent that a 
gravity head pressure differential exists between fuel tank level, 
relative to orifice 90, and the reservoir fuel level in tube 80. Because 
this gravity-induced pressure differential is small as compared to the 
pump suction induced pressure differential when pump 32 is drawing reserve 
fuel via orifice 90, this engine-off "leak" flow rate is much less than 
"reserve pump draw" flow rate. Hence a reserve supply of fuel can be 
maintained in tube 80 available for engine re-start for a predetermined 
prolonged period even under pump inlet starvation conditions, e.g., the 
vehicle parked on a steep incline with a low level of fuel in tank 12. 
In addition, it will be seen that such canister leakage occurring during 
engine (and hence pump) shut-down and low tank level conditions provides a 
backflow reserve fuel stream from orifice 90 into filter chamber 56 and 
then out through the pores of the filter envelope 50 into the main tank. 
This off-period backflow produces a backwashing action on filter 18 to 
cause much, if not all, of any contaminant particles clinging to the 
exterior surface of the filter to be flow carried off of the this surface 
and to re-settle or disperse in the tank. Clogging of filter 18 over its 
operational life is thus greatly reduced. 
It will also now be apparent from the foregoing description and drawings 
that fuel delivery module 10 now enables use of a turbine type rotary vane 
fuel pump, such as that set forth in the aforementioned U.S. Pat. No. 
5,257,916, in association with a reserve fuel reservoir canister without 
thereby disabling the operation of the vapor purging system 35 of the pump 
32. As set forth previously, such disablement could occur if the turbine 
pump were disposed within the interior of the reservoir canister, and the 
outlet of pump purge port 35 were subjected to a gravity pressure head of 
reserve fuel in the canister exceeding the gravity pressure head of the 
main body of fuel in tank 12 by some given disabling amount, say two and 
half inches of water. However, in accordance with this feature of the 
invention, it will be seen that the outlet of the purge port communicates 
directly with the interior of tank 12, outside of reservoir canister 26. 
It will also be seen that the elevation of the outlet of purge passage 35 
is generally at the same elevation of pump inlet 16 where it communicates 
with tank fuel, or only slightly vertically spaced from one another, but 
preferably with the outlet of purge passage 35 being slightly above the 
opening of pump inlet 16 to the tank. Hence the pressure differential 
existing between outlet of purge passage 35 and the pump inlet is 
minimized because they are both exposed directly at about the same 
elevation to only the same main body of fuel in the tank. 
Moreover, with purge outlet 35 at about the same level as the opening of 
pump inlet 16 to the tank, the pressure differential therebetween is 
reversed relative to that which would exist in the case of pump 32 being 
submerged within the body of reserve fuel in a pump-within-canister 
system. Of course, once the tank level is low enough to drop below the 
lower end cap 38 of pump casing 36, the purge passage 35 will be exposed 
directly to the ambient air or vapor in the fuel tank. Thus, under such 
low fuel level conditions in the tank, when filter envelope 18 is starved 
of fuel as described previously and the envelope is acting as a capillary 
seal to the tank interior, the pressure head of reserve fuel in canister 
26 will likewise not adversely effect the vapor purging action of the 
pump. 
From the foregoing it will also now be appreciated that the same favorable 
vapor purging operational characteristics also could be obtained in 
accordance with the invention by mounting a turbine vane type regenerative 
fuel pump of the type disclosed in the aforementioned U.S. Pat. No. 
5,257,916 within a suitably sized reservoir canister, such as that 
disclosed in the aforementioned U.S. Pat. No. 4,747,388 (also incorporated 
herein by reference), provided that the outlet of the purge port passage 
of the in canister pump is communicated directly to the exterior of the 
canister and hence to the tank interior at about pump inlet elevation 
while being isolated from the pressure head of the reserve fuel in the 
canister. This can be accomplished by inserting a small flexible plastic 
vent tube (not shown) at one end into the outlet of port passage 35 and 
leading the other outlet end of the tube in sealed relation and generally 
horizontally from port 35 out through a suitable aperture in the wall of 
the canister and out into the tank so that the vent tube outlet is at 
about the same elevation as the pump inlet. 
However, with the preferred mounting of pump assembly 14 outside canister 
26 and closely adjacent thereto, as illustrated in the first embodiment of 
FIGS. 1 and 2, there is no need for such a vapor purge vent tube 
connection to the tank interior. In addition, when the fuel pump is 
mounted directly in the tank interior, outside the reservoir canister, and 
utilized with a return-type fuel delivery system, the pump is not exposed 
to the hot fuel returned from the engine to the canister but rather is 
cooled by the main body of fuel in the tank, thereby tending to reduce 
flash vaporization of fuel in the pump chamber because of reduced 
temperature of the pump components. 
Second Embodiment 
FIGS. 3-33 illustrate a second embodiment of the invention that also 
utilizes the feature of the invention of mounting a turbine vane fuel pump 
assembly 14, having the aforementioned built-in vapor purging system 33, 
35, 38, outside of, but closely adjacent to a canister reservoir so that 
the pump 32 and its vapor purge outlet 35 are mounted directly in the main 
body of fuel in the tank. In the second embodiment, a fuel 
pump/reservoir/canister base module assembly 110 is provided, preferably 
tank mounted and suspended in a conventional manner so as to be of the 
bottom seeking type, and adapted dimensionally for a drop-in installation 
through an opening in the top wall 24 of tank 12 to rest on its base at 
the bottom of a swivel pot basis 112 in tank 12. 
Module 110 also includes a reservoir canister 120 (see particularly FIGS. 
7-10) open at its upper end to communicate with the headspace or vapor 
dome in the interior of tank 12. Canister 120 is provided with a circular 
opening 124 which receives the cylindrical portion 94 of the housing 96 of 
pressure regulator 22 which is mounted to the canister in the manner of 
the first embodiment assembly 10 described previously. 
Module 110 further includes a base subassembly 130 (shown generally in 
FIGS. 3-6 and in detail in FIGS. 11-18) of generally cylindrical 
configuration diametrically sized to slip through a tank mounting opening 
(not shown) when inserting the module into and through this opening in 
tank top wall 24. Base 130 is open at the bottom and provided at its outer 
periphery with four equally circumferentially spaced legs 132 adapted to 
seat on the swivel pot or tank bottom wall 70. Base 130 has a disc-like 
flange component 133 from which protrudes integrally upwardly a specially 
configured open spider leg mounting boss 134. Boss 134 carries a central 
raised canister mounting ring 136 with an internal bore 138 which receives 
a downwardly protruding neck 140 of the bottom wall 142 of canister 120 
which forms the counter bottom outlet 144. Base 130 is snap-fit assembled 
to the lower end of canister 122 by fitting canister neck 140 in ring 136. 
Module assembly 110 additionally includes the turbine type fuel pump 14. 
Canister 120 is specially shaped (i.e., tall cylinder of narrow diameter) 
and laterally offset on base 130 to provide an exterior side nesting space 
for accommodating pump 14 in nested relation along one side of canister 
120. Pump 14 in assembly thus does not protrude beyond the exterior 
dimensions of base 130 to permit module 110 to be fitted within the tank 
top wall opening when pump 14 is in assembled relation as part of module 
110. 
The flat wall 146 of flange 133 in the pump recess area adjacent canister 
120 is provided with an upwardly flanged neck 148 to receive an 
anti-rotation rubber grommet seal (not shown). When base 130 is snap fit 
to canister 120, the pump inlet boss 16 is also sealably received with a 
press fit in the grommet and flange neck 148 to thereby mount the lower 
end of the pump on base 130 after pump 14 has been preassembled to 
canister 120. Wall 146 of flange 133 is also provided with an upwardly 
protruding horizontally elongated open top drain trough 150 constructed as 
shown in detail in FIGS. 13-17 which extends from a curved end wall 152 to 
an open end outlet 154 leading to the edge of a circular opening 156 in 
flange wall 146. When pump 14 is mounted on flange 133 its vapor purge 
outlet port 35 is aligned over an inclined ramp 158 of trough 150 so that 
fuel expelled from the pump chamber 33 of pump 32 via the purge port 35 is 
directed into trough 150 and is channeled by the trough into flange 
opening 156. 
As best seen in the exploded perspective views of FIGS. 11 and 12 and in 
the detail views of FIGS. 19-33, the remaining components of base assembly 
130, in addition to flange 133, include a filter diaphragm 160, a 
ring-like diaphragm retainer 162 which overlies and is heat sealed to the 
outer peripheral edge of filter diaphragm 160, a spring cup 164 provided 
with a central calibrated orifice 166, a coil compression spring 168 
having its upper coil nested in the turned-down flange 170 of cup 164, a 
spring retainer 170, a ring-like main filter retainer 172, a main filter 
support 174 and a disc-like main filter 176. The foregoing components of 
base assembly 130 are constructed to the configuration and geometry shown 
in the detail engineering views of FIGS. 19-33 and are scaled relative to 
one another as shown in perspective views of FIGS. 11 and 12, which also 
illustrate the order of their stack-up assembled relationship with flange 
133. The base components are shown in final assembly in FIGS. 5 and 6. 
Referring to FIG. 5, in conjunction with FIGS. 11-33, it will be seen that 
base 133 has a circular flange 180 (see also FIGS. 15 and 16) that defines 
the throughopening 156 in flange wall 146. Diaphragm retainer 162, with 
filter diaphragm 160 attached thereto at its outer edge, is press fit into 
flange 180 so that filter diaphragm 160 spans across opening 156 
immediately beneath the outwardly flared lower annular edge 182 of 
canister neck 140. Spring retainer 170 is subassembled with spring 168, 
the spring bottom coil being seated on a downwardly indented central 
imperforate spring seat portion 182 of spring retainer 170. Spring cup 164 
rests on the top coil of spring 168 with its peripheral flange 169 
oriented downwardly. This subassembly is then inserted with a press fit 
upwardly into flange 180 in clamping relation with diaphragm retainer 162, 
to the position shown in FIG. 5. 
The main or primary filter 176 is heat sealed or otherwise suitably fixedly 
bonded at its outer edge to the underside of filter retainer 172. Filter 
support 174 is a wagon wheel type open grid with dual concentric rim and 
inner rings 192 and 198, and is suitably centered on and fixed to the 
upper surface of filter 176 as shown in FIGS. 5 and 6. This main filter 
subassembly is telescopically press fit into the mating annular seat 
provided by the peripheral flange rim or skirt 184 which encircles the 
outer periphery of wall 146. The assembled position of primary filter 176, 
associated retainer 172 and filter support 174 is shown in FIGS. 5 and 6. 
As so final assembled, base 130 of module assembly 110 in operative 
position rests on bottom wall 70 of the swirl pot 112 (or similarly on the 
conventional fuel tank bottom wall), and defines a main filter chamber 186 
in the space beneath flange wall 146 and above primary or main filter 176. 
Chamber 186 communicates with both the fuel pump inlet 116 and with the 
space beneath the secondary filter diaphragm 160 through the open spokes 
of spring retainer 170. The primary fuel flow path from the fuel in swirl 
pot 112 into chamber 186 is through the clearance spaces between stand-off 
feet 132 and the under edge of skirt 184, and thence through main filter 
176 into chamber 186. A parallel or secondary fuel flow path from the tank 
and swirl pot to main filter chamber 186 is provided by the four wide 
openings existing between the four spider legs 188 of canister support 
boss 134 of base 130, thence through the filter screen material of the 
filter diaphragm 160 and thence through the spaces between wagon wheel 
spokes 190 of filter support 174. In addition, as indicated previously, 
vapor purge bypass fuel exiting via purge port 35 is channeled by trough 
150 into opening 156 to flow downwardly through filter diaphragm 160 into 
main filter chamber 186. 
Upward movement of main filter 176 is limited by filter support 174 
abutting at its outer rim 192 against the underside of a row of seven 
stand-off feet 194, and by inner ring 198 of filter support 170 abutting 
spring seat 182 of spring retainer 170. 
In one alternative version of module assembly 110, spring cup 164 is 
provided with the calibrated central orifice 166 which registers with the 
circular central region 161 of diaphragm 160. Thus when orifice 166 is 
present it will also be seen that there is an always-open fuel flow path 
from the reserve fuel reservoir 121 of canister 120 downwardly through 
neck outlet 144, through the central region 161 of filter diaphragm 160, 
then downwardly through cup orifice 166 and thence out through the spaced 
coils of spring 168 into main filter chamber 186. 
Alternatively, spring cup 164 can be made completely imperforate by 
elimination of calibrated orifice 166 therein so that the same operates to 
completely close and seal outlet 144 when spring 168 is biasing diaphragm 
filter 160 against the canister outlet annular valve seat formed by neck 
edge 182. This full sealing valve action can also be obtained by molding 
in a suitable rubber sealant material to thereby embed the mesh filter 
material of filter diaphragm 160 in this imperforate rubber material. The 
central region 161 of filter diaphragm 160 will thereby serve as an 
imperforate valve closure member overlying spring cup 164. Either form of 
spring cup 164 also functions to protect the material of diaphragm filter 
160 from undue wear or being torn by the spring end coil. 
In use, the fuel pump and canister module 110 is mounted in the fuel tank 
12 with the reservoir canister 120 extending generally vertically so that 
primary fuel filter 176 is disposed immediately adjacent the bottom wall 
70 of swivel pot 112 or the fuel tank and preferably resting thereon. In 
normal use the fuel tank is at least partially full of liquid fuel, such 
as gasoline, to a level above both primary filter 176 as well as secondary 
diaphragm filter 160 so that these filters and the pump inlet 16 are 
completely submerged in the main body of tank fuel or at least the body of 
fuel in swirl pot 112. 
In the normal operation of pump assembly 14, fuel is drawn from the main 
body of fuel in the tank via both filters 176 and 160 into main filter 
chamber 186 and thence into pump inlet 16. A variable fuel flow is 
discharged from the pump outlet 42 and via line 24 to the engine fuel rail 
(not shown) at substantially constant pressure, such as 50 psig. Again 
regulator 22 maintains a substantially constant output pressure by 
return-bypassing a portion of the fuel supplied in excess of engine 
demand, the regulator discharging the excess bypassed fuel through its 
outlet 28 into the upper region of reservoir chamber 121 of canister 120. 
In normal operation of the pump, fuel in the reservoir canister 120 rises 
to a level which is usually adjacent or somewhat below the open upper end 
122 of canister 120. In some normal operating conditions, such as extended 
periods of the engine idling or operating under a lower load, the fuel 
rises to the top of canister 120 and overflows through the open upper end 
122 of the canister into the main body of fuel in the swivel pot 112 or 
into the fuel level is above the swivel pot tank. 
Under low tank fuel level conditions the pump inlet 16 can be starved when 
the remaining fuel in the tank moves away from both the primary filter 176 
as well as secondary diaphragm filter 160, such as during the 
aforementioned cornering of the vehicle and/or severe inclination of the 
tank. The filter screen mesh material of both diaphragm filter 160 and 
main filter 176 will likewise be starved of fuel but will remain wet with 
fuel. Under these conditions, air in the main tank being drawn toward the 
pump inlet by pump suction will try to pass through these filter 
materials. However these wet filters will reject the passage of air due to 
the liquid capillary seal of these wet filter materials. The pressure drop 
in chamber 186 below diaphragm filter 160 created by the pump will then 
cause the filter to act as a diaphragm to move it downwardly. This motion 
will compress spring 168 and lower the material of filter 160 downwardly 
off its neck seat 182 to thereby open communication via the relatively 
large diameter outlet 144 between reservoir chamber 121 and the area over 
the upper surface of filter 160. Reserve fuel may then flow rapidly 
downwardly from the reservoir canister outlet and laterally over and 
through diaphragm 160 into main filter chamber 186, and thence to the pump 
inlet to thereby keep fuel flowing to the engine, and without breaking the 
capillary sealing effect across filters 176 and 160 due to system 
balancing of forces. When fuel is again available from the main body of 
fuel into the tank to again submerge main filter 176 the capillary seal 
effect will be broken across filter 176, thereby allowing fuel to pass 
through primary filter 176 and into chamber 186 to feed the pump inlet. 
This inflow also reduces the downwardly acting pressure differential on 
secondary filter diaphragm 160. Also, if diaphragm 160 is likewise 
re-immersed in tank fuel the capillary seal effect across filter 160 will 
also be broken. This allows spring 168 to force the filter 160 upwardly 
back to its normal position adjacent canister outlet seat 182. If rubber 
seal 161 is present on diaphragm 160 it will be reclosed on seat 182 by 
spring 168 to thus stop the flow of reserve fuel from reservoir 121 to the 
pump inlet 16. 
If seal 161 is not present on filter 160, canister outlet 144 will still be 
closed, but not sealed, by the mesh filter material forced across seat 
182. Hence a controlled but continuous flow of reserve fuel will occur 
from reservoir 121 through the center portion of permeable zone 161, 
through spring cup orifice 166 and through the spaces between the coil of 
spring 168 into main filter chamber 186. Thus when tank fuel level is 
below the top of the canister, the pump will draw from the reservoir and 
tank in an inverse ratio to maintain by the pressure balancing effect a 
reserve head of fuel in the canister. 
As in the first embodiment of FIGS. 1 and 2, cup orifice 166 is calibrated 
(e.g., 0.40 mm diameter) to provide the aforementioned "balance" to 
maintain a maximum head of reserve fuel in canister 120 and a minimum 
overflow from canister during normal fuel delivery system operation. This 
assures that a sufficient quantity of reserve bypass fuel will be 
available for pump input draw when the pump inlet is starved of fuel from 
the main tank, while also maximizing return of twice filtered bypassed 
fuel during normal pump operation under non-starvation conditions. 
In addition, at system shut-down, when the vehicle engine is turned off, 
and whenever a gravity head pressure differential exists due to the level 
of fuel in reservoir 120 being above that of the main body of fuel in the 
tank, the reserve fuel will drain from reservoir 121 through filter 160 
and cup orifice 166 into the main filter chamber 186 and then out through 
primary filter 176 and secondary filter 160 into the tank. This reverse 
fuel flow through these filters will produce a backwash effect on both 
filters 160 and 176 tending to wash away tank contaminant particles 
clinging to the exterior surfaces of these filters. Therefore the rate at 
which these filters can become clogged over the operational life of the 
system is greatly reduced. 
When diaphragm 160 is made imperforate in its central region 161 by the 
provision of the aforementioned rubber sealing material for engagement 
with canister valve seat 182, and/or by the provision of a imperforate 
spring cup 164 (orifice 166 not provided therein) system shut down gravity 
differential flow of reserve fuel via bottom outlet 144 can be 
substantially if not completely prevented by spring 168 closing the filter 
diaphragm valve structure. In this event the quantity of reserve fuel 
available for system start up can be preserved for greatly prolonged 
periods of shut down even under low main tank fuel level conditions. 
Moreover, with either type of canister valve closing mode (i.e., with or 
without always-open canister fuel flow through outlet 144 and calibrated 
orifice 166), whenever the pump-induced fluid pressure differential acting 
between main filter chamber 186 and filter diaphragm 160 becomes operable 
to pull diaphragm 160 downwardly to unseat the same from outlet valve seat 
182 (as when filter 176 and 160 are starved of main tank fuel) the 
resultant increased flow of fuel from outlet 144 onto the upper surface of 
diaphragm 160 (which can be at a much higher flow rate than that through 
orifice 166), as indicated by the arrows in FIG. 6, has a 
"fountain-washing" effect on the upper exterior surface of filter 160. 
This effect is enhanced by the cooperative geometry of filter diaphragm 
160, i.e., being raised in the center by spring 168 and recessed 
downwardly therefrom in a conical formation out to the periphery of the 
filter at diaphragm retainer 162. This down-flow of fuel as it exits 
outlet 144 tends to radially spread out in a full circle pattern as it is 
initially flowing along the exterior surface of filter 160 radially 
outwardly of the central area 161, and as it is being drawn by the 
pressure differential through filter 160 into chamber 186. Hence this 
fountain flow tends to keep the exterior surface of filter 160 washed free 
of contaminant clogging, particularly in an annular zone immediately 
adjacent and surrounding central region 161. Secondary filter 160 
therefore tends to remain unclogged by tank contaminants for a longer 
period than primary filter 176 because of this fountain washing effect, 
and also due to the disposition of secondary filter 160 at a higher 
elevation than primary filter 176, i.e., on the top side of base 130 
versus the underside thereof. This system operational effect provides an 
enhanced fail-safe feature insofar as it provides an auxiliary fuel inflow 
path from the main tank body of fuel through secondary filter 160 in 
parallel with that through primary filter 176 to main filter chamber 186 
and thence to pump inlet 16. Hence even when primary filter 176 is 
severely clogged with tank contaminants the fuel delivery system can 
remain operable for a prolonged period by drawing fuel from the main body 
of fuel in the tank through only secondary filter 160. 
It is also possible with the system of the second embodiment of the 
invention to vary by empirical design the balance between the upward bias 
of spring 168 versus the forces generated by fluid pressure differential 
between canister fuel head versus that of the tank, and the forces 
generated by pump suction, so that there is a supplementary and variable 
canister outflow of reserve fuel passing through filter 160 into chamber 
186 additive to the flow through cup orifice 166 and at a much greater 
flow rate. Such fuel draw from canister reservoir 121 thus can be designed 
to occur in parallel balance with, and concurrently with, pump fuel draw 
from the tank through filters 176 and 160 under non-starvation conditions. 
It will be noted that the valve structure of filter diaphragm 160 is 
arranged to open in the direction of flow out of canister outlet 144 into 
main chamber 186, and likewise to open in the direction of flow from the 
main body of fuel tank through filter diaphragm 160 into chamber 186, and 
to merge toward the pump inlet 16, under both starvation and 
non-starvation conditions. Hence operation of pump 14 will tend to open 
canister outlet 144 under both conditions but with varying effect 
depending on which of these conditions are effective or controlling at any 
given time. Thus the variable flow rate control provided by the fixed 
calibrated orifice 166 can be modulated and augmented by the variable 
downwardly opening action of diaphragm 160. Thus orifice 161 and spring 
168 can be designed to work together to better achieve canister bypass 
fuel head balancing conditions in order to match system operational and 
performance parameters in achieving the aforementioned maximization of 
return of bypass fuel to pump inlet during normal system operation under 
non-starvation conditions. 
Indeed, even when orifice 166 is omitted and spring cup 164 made 
imperforate, and/or an imperforate rubber seal is provided in the central 
region 161 of filter diaphragm 160, this balancing of canister head level 
to minimize canister overflow and maximize return of canister bypass fuel 
to the pump can be obtained by design and selection by spring 168. Thus 
spring 168 can be selected to exert a very light upwardly biasing force on 
filter diaphragm 160, i.e., only sufficient to maintain outlet 144 closed 
and sealed at system shut down when opening pressure differential across 
the valve is created only by gravity head differential between canister 
head and main tank head. This at most may only be 4 to 8 inches of fuel in 
canister 120 when the main tank is empty. When the fuel delivery system is 
operational with the vehicle engine running the increased pressure 
differential acting on diaphragm 160 in response to the effect of pump 
suction at inlet 16 will be additive to such gravity head generated 
pressure differential, and spring 168 can be designed to then yield in a 
downwardly valve opening direction under such conditions. 
It is also possible to still obtain the filter backwash effect even with an 
imperforate valve member provided on or in association with filter 
diaphragm 160 and central region 161. Thus at system shut down spring 168 
can be selected to allow leakage of bypass fuel from reservoir 121 from 
say completely full to half full whenever the main tank is empty or at 
some very low level condition. Although this backwashing effect may thus 
not occur very often during the service life of the vehicle and fuel 
delivery system, even creating the possibility of such an event occurring 
infrequently can enhance operational life of the fuel delivery system. 
Moreover, it is precisely at these very low tank fuel level conditions 
that filter clogging conditions become aggravated because contaminant 
concentration at the filters increases for a fixed quantity of contaminant 
particles in the fuel tank as the volume of the main fuel body in the tank 
decreases. Also for this reason maximizing use of twice-filtered fuel 
through the pump becomes more beneficial in proportion to the drop in main 
tank fuel level in preventing fuel injector clogging and/or downstream 
fuel line filter clogging. 
Hence the second embodiment of the invention readily can be made operable, 
as in the system of the aforementioned U.S. Pat. No. 4,747,388 such that 
reserve fuel is drawn from the canister reservoir 121 only as and when 
needed to keep fuel flowing to the engine under main tank pump starvation 
conditions. Module 120 can thus provide a large reserve fuel capacity to 
ensure extended vehicle operation under tank empty conditions, or for 
restarting the vehicle when parked on incline with a low tank fuel level. 
On the other hand, when the aforementioned filter backwashing capability 
at system shut-down is provided, and hence canister 120 loses some 
volumetric capacity reserve duration by loss to backwash outflow, it still 
is possible to obtain both beneficial effects, albeit each to a lesser 
extent. Again, mounting pump 140 directly in the main body of the fuel of 
the tank, outside of canister 120, enhances pump cooling and isolates it 
from any hot fuel conditions which may occur within the canister 
reservoir. 
Also, in accordance with another one of the aforementioned features of the 
invention, the second embodiment enables the use of a turbine vane type 
rotary pump with a built-in vapor purging system to be operable as 
intended and in an enhanced manner, while still providing all of the 
advantages of a large reserve supply of fuel selectable as needed from the 
associated canister reservoir. Again it will be seen that the outlet of 
vapor purge port passage 35 is only slightly above the elevation of the 
pump inlet 162, as well as being laterally adjacent the bottom region of 
the reservoir chamber 121 of canister 120. In addition at least 
once-filtered fuel exiting pump chamber 33 via purge port 35 is returned 
to the main filter chamber 186 via trough 150 and filter diaphragm 160. 
Hence this now twice-filtered additional bypass fuel is returned to the 
pump inlet instead of being wasted by uncontrolled outflow to the tank 
fuel body. This further consevation of bypass fuel use again becomes 
particularly beneficial under very low tank level and/or pump starvation 
vehicle operational conditions. 
The spoked spring retainer disc 170, filter diaphragm valve 160 and spring 
168 provide a simple and economical valve actuating mechanism for opening 
and closing flow of reserve fuel to pump 14. In one mode of operation of 
valve 160 no reserve fuel will be lost to the tank when not needed by pump 
14. On the other hand, since the pressure head of fuel in canister 120 
acts in the direction tending to unseat valve 160, spring 226 can be made 
inexpensively as a light spring exerting minimal biasing force to allow 
diaphragm valve 160 to augment orifice flow and/or provide filter backwash 
flow. 
In addition, locating the pump vapor purge passageways outside the 
reservoir canister also removes this reserve fuel reverse leak path 
through the pump when it is shut down, thereby eliminating the need for a 
pump inlet back check valve or foot valve type canister containment 
structure otherwise required to prevent such canister leak down through 
the pump vapor purge passageway. 
Base 130, due to its use of flat, circular geometry in its multiple 
components, as herein disclosed in the form of the engineering scale views 
of FIGS. 11-33, is readily and economically manufacturable with plastic 
injection molding processes and equipment from a suitable fuel-compatible 
plastic, such as Acetal (except for the filter screen material of filters 
160 and 176). Preferably the filter screen material is 70 micron mesh 
nylon 6 square weave for primary filter 176, and 62 micron mesh nylon 6 
square weave for secondary filter diaphragm 160. The telescopic stack-up 
array of components 160, 162, 168 and 170 upwardly into base flange 133, 
and similarly the telescopic insertion of main fuel filter components 172, 
184 and 176 into base flange 184, provide economies in part and assembly 
costs as well as service costs. The snap-together assembly of the pump and 
canister components on base 130 also contribute to manufacturing cost 
reduction. 
Third Embodiment 
FIGS. 34-39 illustrate a third embodiment pump/canister/base module 
assembly 300 of the invention that utilizes the same pump assembly 14, 
bypass regulator subassembly 22 and base subassembly 130 as module 
assembly 110. However module assembly 300 uses a modified canister 
reservoir 302 constructed as shown to scale in FIGS. 34-39. Canister 302 
has a generally "D-shape" in horizontal cross section, as best seen in 
FIGS. 35, 38 and 39. The bottom wall 304 of canister 302 is again provided 
with the neck outlet 140 to snap fit with mounting neck 136 of base spider 
134 (FIG. 34). A major portion of the vertically oriented side wall of 
canister 302 is made up of cylindrically shaped upper and lower wall 
sections 306 and 308 integrally joined by a horizontal shelf wall section 
310. The outside diameter of upper wall section 306 is made to the same as 
that of flange 133 so that the overall horizontal dimension of canister 
302 does not increase the overall diameter of module assembly 300. 
Canister 302 is indented in its side wall formation in the area of pump 14 
so that the pump has a recessed mounting relative to canister 302. For 
this purpose canister 302 has two upper chordal wall sections 312 and 314 
joined by shelf wall sections 316 and 318 respectively to complemental 
lower chordal wall sections 320 and 322, wall sections 312 and 314 being 
generally coplanar with the axis of pump 14. The canister side wall 
indentation adjacent pump 14 is formed by pocket walls 324 and 326 of 
concave curvature facing pump 14, and these are joined by a T-cross 
section wall section 328 (FIGS. 35, 38 and 39). 
Pump 14 nests in the space between wall sections 324 and 326 and is mounted 
on base 130 in the same manner and location as in module assembly 110. 
However flange 100 of the bypass regulator 122 has a complemental 
downwardly sliding insertion fit into the T-section cavity of the T-wall 
328, as best seen in FIG. 35. This sliding insertion T-lock 
interengagement between regulator flange 100 and canister wall T-section 
328 provides the upper module support interconnection for the pump and 
canister. Their snap-in mounting on base 130 provides the lower module 
support interconnection. Wall T-section 328 is provided with an upwardly 
opening notch 330 for receiving the cylindrical portion 94 of pressure 
regulating housing 96. The regulator outlet 28 thus protrudes into the 
uppermost region of canister 302 with maximum spacing from the opposed 
face of upper wall section 306 and is generally vertically aligned above 
canister outlet 144. 
It will thus be seen that canister 302 maximizes the space available above 
base 130 to thereby increase bypass reserve fuel capacity of module 
assembly 300. For example when base flange 133 has an outside diameter of 
5 inches and canister 302 is constructed to the scale of FIGS. 34-39 
relative to base 130, the canister may have a reservoir capacity of 
approximately 700 to 750 millimeters. By contrast, canister 120 when 
configured as shown in FIGS. 3-6 and constructed to the scale of FIGS. 
7-10 relative to the same diameter base 133 has a capacity of 
approximately 300 millimeters. Thus although canister 302 is slightly more 
costly in terms of material and tooling costs than canister 120, the large 
increase in reserve capacity provides an economical cost/benefit ratio in 
many applications that still require a relatively small outside diameter 
module to fit within relatively small tank openings. In addition, all of 
the previously described features and advantages of module assembly 110 
are still obtained with module assembly 300.