Fuel pump and motor assembly

A compact pump and motor assembly adapted for use as a fuel controller for an internal combustion engine fuel metering system. The assembly contains an electric motor, an interface housing assembly at one end of the electric motor and a pump housing assembly disposed on the side of the interface housing assembly opposite that of the motor. The motor shaft extends through the interface housing into a pilot hole in the pump housing and drives a pumping means contained within a pumping chamber defined by the pump housing and the interface housing. An inlet port, an outlet port, and a return port are provided in the pump housing. An inlet passage extends from the inlet port through the gear pump housing and the interface housing into a vapor separation chamber contained within the casing of the motor, the motor being of the wet type. A passage in the interface housing extends from the vapor separation chamber to the inlet of the pumping chamber. An outlet passage in the pump housing extends from the outlet of the pumping chamber to the outlet port. A passage shunting the pumping chamber extends in the interface housing and the pump housing from the vapor separation chamber to the return port, and contained therein is a low pressure regulator valve which regulates pressure in the vapor separation chamber. A further passage extends in the pump housing from the pumping chamber outlet to the return port and a valve assembly is contained therein for diverting a portion of the pump output to the return port under certain conditions at the pumping chamber outlet.

BACKGROUND AND SUMMARY OF THE INVENTION 
This invention pertains to a pump and motor assembly which is particularly 
adapted for use as a fuel controller for an internal combustion engine 
fuel metering system. 
The present invention is concerned particularly with providing a compact 
pump and motor assembly which may be used in an electronic fuel metering 
system of the type disclosed in applicant's co-pending application Ser. 
No. 798,715 filed May 19, 1977, entitled "Fuel Circuit for an Internal 
Combustion Engine". 
Briefly, an electronic fuel metering system of the type disclosed in the 
co-pending application operates an electric motor driven control pump in 
such a manner the pump delivers the correct amount of fuel required for 
operation of the engine. It has been discovered to be advantageous to 
mount the fuel pump and motor assembly as close as possible to the point 
at which the fuel is distributed for mixture with air ingested by the 
engine to form the combustible mixture. In the typical automotive vehicle, 
this means that the fuel pump and motor assembly should be mounted 
directly on the engine, for example, within the confines of the usual air 
filter housing. In order to make such mounting feasible it becomes 
desirable to make the pump and motor assembly as compact as possible. The 
present invention in one respect is concerned with providing such a pump 
and motor assembly. The invention is also directed to an improved assembly 
which utilizes fewer parts, is more economical, and greatly minimizes the 
adverse effect of once-per-revolution friction variations on flow 
variation. 
Features, advantages and benefits of the invention will be seen in the 
ensuing description and claims which should be considered in conjunction 
with the accompanying drawings which illustrate an examplary but presently 
preferred embodiment according to the best mode presently contemplated in 
carrying out the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 illustrates a pump and motor assembly 30 embodying principles of the 
present invention and comprising three principal sections which are an 
electric motor assembly 32, an interface housing assembly 34 and a pump 
housing assembly 36. These three sections are assembled together axially 
with interface housing assembly 34 being disposed between electric motor 
assembly 32 and pump housing assembly 36. 
Electric motor 32 is a generally conventional wet type motor which may be 
used in gasoline fuel systems. Motor 32 comprises an armature shaft 38 
having an armature structure 40 disposed thereon. The right-hand end of 
shaft 38 as viewed in FIG. 1 is journaled by means of a spherical journal 
bearing 42 in an end closure member 44 which encloses the right-hand end 
of the assembly. The opposite end of shaft 38 is similarly journaled in 
the housing proper 34a of interface housing in a manner which will be 
explained in detail later. A cylindrical casing 46 extends between end 
closure member 44 and interface housing 34a around armature 40 to thereby 
define a chamber, hereinafter referred to as the vapor separation chamber 
48 for reasons which will be subsequently explained. A suitable magnetic 
field structure 50 is disposed on the inner wall of casing 46 around 
armature 40 to provide the required magnetic field for the motor. The 
commutator is indicated at 52 and electric power is supplied via brushes 
(not shown) engaging commutator 52 which are connected to respective 
electric terminals 54, 56 which extend through but are insulatingly 
supported on end closure member 44. The components constituting electric 
motor 32 are held in assembled position on interface housing 34a by means 
of three through bolts 58a, 58b, 58c passing through clearance holes in 
member 44 to engage tapped holes 59a, 59b, 59c, respectively extending 
completely through interface housing 34a as indicated. It will be 
appreciated therefore that when electrical power is supplied to terminals 
54 and 56, the armature shaft 38 is caused to rotate and thereby operate 
the pumping mechanism hereinafter described, the motor speed being 
variable as a function of the electrical input to the terminals. 
Attention is next directed to FIGS. 4 through 14 which illustrate pump 
housing assembly 36 in detail. Assembly 36 comprises a pump housing proper 
36a having a planar right-hand (as viewed in FIG. 1) face disposed against 
a corresponding left-hand face of interface housing 34a. Assembly of the 
two housings is accomplished by means of three through bolts 60a, 60b, 60c 
(FIG. 1) which pass respectively through three clearance holes 62 in 
housing 36a to engaged tapped holes 59d, 59b, 59c, respectively in housing 
34, as shown. A pumping chamber generally indicated by the numeral 64 is 
fashioned in said right-hand face of housing 36a and is bounded by a 
circular groove 66. A compressible resilient O-ring seal 68 (FIG. 7) which 
is impervious to the pumped fluid is lodged in groove 66 to provide for a 
seal between the two housings 34a, 36a around the pumping chamber 64. 
Pumping chamber 64 is configured for a gear type pumping mechanism 70 
(FIG. 5) comprising a pair of meshed gears 72 and 74 respectively. Gear 72 
is the driving gear which is keyed to the protruding end of armature shaft 
38. Gear 74 is the driven gear which is journaled on a stub shaft 76. 
Pumping chamber 64 is formed by two intersecting circular gear recesses 78 
and 80 respectively for gears 72 and 74 respectively, the recesses being 
formed in the face of housing 36a which is disposed against housing 34a. A 
pilot hole 82 is fashioned concentrically with recess 78 to provide a 
pilot for the free end of armature shaft 38 during assembly of the 
components as will be explained in greater detail later. A similar pilot 
hole 84 concentric with recess 80 is provided for stub shaft 76. As viewed 
in FIG. 7 an inlet 86 is provided on the left-hand side of the 
intersection of the two recesses 78 and 80 and an outlet 88 is provided on 
the right-hand side. The pumping chamber is thereby defined by a pair of 
axial end walls, one each provided by each housing 34a, 36a, and is 
bounded peripherally by a peripheral wall defined by the two intersecting 
circles. It will therefore be appreciated that with this arrangement fluid 
is pumped from inlet 86 to outlet 88 by means of pumping mechanism 70 when 
motor 32 is operated to rotate shaft 38. 
Housing 36a is also fashioned with three ports to which external lines are 
adapted to be connected. An inlet port 90 is intended to be connected to a 
source of fuel, such as a fuel tank, via an inlet supply line (not shown) 
which connects to inlet port 90. Return port 92 is intended to return 
fluid to the tank via a return line (not shown) which connects to return 
port 92. Outlet port 94 is intended to be connected to the distribution 
system of the engine via an outlet line (not shown) which connects to 
outlet port 94. Connection of the lines to the ports may be accomplished 
in any of the usual ways. One way is by tapping the ports, as is the case 
for ports 92 and 90, and using threaded line fittings. Another way is to 
flange the line and use a screw and retainer indicated at 96 for port 94 
to hold the flanged line in place. 
Inlet port 90 leads to a passage 98 which extends through housing 36a 
parallel to the axis of the pump and motor assembly 30. As can be seen in 
FIG. 7 a circular groove 100 is provided in the right-hand face of housing 
36a around passage 98 to receive an O-ring seal 102 which seals around the 
passage between the two housings 34a, 36a. Passage 98 forms the beginning 
of a passage which is continued through housing 34a by the passage 104 
(see FIG. 18) and which leads to vapor separation chamber 48. 
In pump housing 36a outlet 88 of the pumping chamber connects to outlet 
port 94 by means of several interior passage segments. These several 
segments include an axial passage 106 leading directly from outlet 88 and 
a radial passage 108 which intersects passage 106 as shown in FIG. 12. 
Passage 108 in turn leads to an enlarged circular bore 110 which forms a 
flow-transducer-receiving receptacle for a fluid flow transducer assembly 
112 shown only in FIG. 4. Flow transducer assembly 112 may be generally of 
the type shown in U.S. Pat. No. 3,814,935 dated June 4, 1974 and comprises 
a rotatably mounted paddle wheel 114 which rotates at a velocity 
corresponding to the flow rate of fluid which is directed generally 
tangentially against the periphery of the segments of the paddle wheel. A 
light source and light responsive pick-up (not shown) are disposed to 
monitor the velocity of the paddle wheel and develop an electrical signal 
for use in the electronic fuel metering system with which the pump and 
motor assembly may be used. Electrical circuitry is associated with this 
arrangement and is conveniently contained on an electronic circuit module 
package 116 which is disposed exteriorly of the housing 36 over the 
receptacle 110 and transducer 112 contained therein, the package being 
fastened to the latter. The assemblage consisting of the flow transducer 
112 and the electronic package 116 is secured to housing 36a by means of 
screws (not shown) which pass through holes 118 in the electronic package 
116 to engage corresponding holes 120 formed in upstanding bosses on the 
top of housing 36a. The fluid passage through the flow transducer is 
indicated by the reference numeral 122 with fluid after passing through 
the flow transducer being conducted into the free space within the 
interior of receptacle 110 around the outside of the transducer body. 
Communication from there to outlet port 94 is established by means of a 
passage 124 extending from port 94 to tangentially intercept the wall of 
receptacle 110. As can be seen in the drawings, appropriate seals and 
locating means are provided for flow transducer assembly 112 and 
associated circuit package 116. 
Return port 92 is also connected with outlet 88 by means of internal 
passages in housing 36a. Passage 108 is intersected just below its point 
of intersection with receptacle 110 by means of a passage 126 which is 
formed as a bore extending from the exterior boss 128. After boring, the 
passage 126 is closed off by means of a suitable closure at boss 128. 
Passage 126 intercepts a further passage, generally 130, which is formed 
as a bore and sequence of counterbores from the surface 132 of housing 
36a. As will be subsequently explained, passage 130 is shaped in this 
manner to receive an orifice bypass valve assembly which is utilized to 
divert a portion of the pump output from outlet port 94 to return port 92 
in response to selected conditions occurring at the outlet 88 of the 
pumping chamber 64. Passage 130 intercepts an axial passage 134 which 
extends through housing 36a from return port 92. As shown in FIG. 9, the 
orifice bypass valve assembly 136 is assembled into passage 130 and the 
open upper end of passage 130 above the point at which passage 126 
intersects is closed by means of a closure 137. While further details of 
the manner of operation of valve assembly 136 will be explained later 
suffice it to say for the present that the valve assembly operates to 
selectively divert a portion of the pump output back to the tank via the 
return port under certain conditions at the outlet 88 of the pumping 
chamber. 
Consideration is now directed to details of interface housing 34a as shown 
in FIGS. 17 through 21. The interface housing proper 34a contains, as 
explained above, the threaded attaching holes for the bolts 58a, 58b, 58c, 
60a, 60b, 60c which respectively hold electric motor assembly 32 and pump 
housing assembly 36 thereto in assembled relation. Additionally, housing 
34a contains an axial hole 138 for the motor armature shaft 38 which 
extends through housing 34a and is configured to receive the journal 
bearing and retainer used to journal the armature shaft in passing through 
hole 138. As explained earlier the axial passage 104 through housing 34a 
continues the inlet passage from inlet port 90 into the vapor separation 
chamber 48. The purpose of vapor separation chamber 48 is to provide a 
solid head of liquid fuel to the inlet of the pumping chamber which is 
free from entrained vapor. Accordingly, the skewed passage 140 is provided 
through housing 34a extending from the lower level of vapor separation 
chamber 48 to communicate with inlet 86 of pumping chamber 64. In order to 
return excess vapor and excess liquid entrained with vapor to the tank a 
low pressure regulator valve assembly is incorporated into interface 
housing assembly 34. For this purpose, a passage 142 in housing 34a 
extends from the upper head space of the vapor separation chamber to 
intercept a vertical passage indicated generally at 144. The vertical 
passage is formed as a bore and series of counterbores in much the same 
manner as was passage 130 in housing 36a to accommodate the valve assembly 
which is disposed therein. The lower end of passage 144 intercepts an 
axial passage 146 which is continued by the passage 134 in housing 36a to 
lead to return port 92. A suitable groove and O-ring seal are provided in 
housing 36a around passage 134 to provide for sealing between the two 
housings 34a, 36a around the passage. As shown in FIG. 21, the low 
pressure regulator valve assembly 148 is lodged in passage 144 at a level 
below that at which passage 142 intersects and the open upper end of 
passage 144 is closed by a closure 150. The low pressure regulator valve 
assembly 148 is essentially a normally closed pressure relief valve which 
opens when the pressure acting on the valve assembly as communicated from 
vapor separation chamber 48 exceeds the valve setting at which point the 
valve opens to conduct vapor and liquid entrained with vapor back to the 
tank via return port 92. It should also be pointed out that housing 
element 34a is provided with a pair of mounting holes 151 via which bolts 
(not shown) may be passed to secure the assembly to support structure 
forming the base of the air cleaner housing of the engine with which the 
pump and motor assembly may be used. 
It is also preferable to include a fine mesh filter screen to filter any 
contaminating particles which may have entered the vapor separation 
chamber so that these are not transmitted through to either of the pumping 
mechanism or to the valve assembly 148 where they might interfere with the 
proper operation of these respective components. Accordingly, as shown in 
FIG. 3 such a filter screen 152 in the form of an assembly is secured to 
the right-hand face of interface housing 34a by means of retention 
elements 154 which engage a pair of diametrically opposite mounting studs 
156 which are fashioned integrally with housing 34a. Details of the screen 
construction are shown in FIGS. 22 and 23. 
Details of the preferred construction for gear 72 are shown in FIGS. 14, 15 
and 16. Gear 72 comprises a series of teeth 159 distributed around the 
outer periphery thereof and a central axial bore comprised of three 
sections 168, 170, and 172. A pair of diametrically opposed axial slots 
164 extend the full length of the gear bore and provide for assembly of 
the gear to armature shaft 38 as will be explained. The purpose of the 
three sections 168, 170 and 172 is to permit gear 72 to rock slightly on 
armature shaft 38 but without allowing the gear to exceed a specified 
concentricity limit on the armature shaft. With such a capability, 
once-per-revolution friction variation is minimized, and correspondingly 
fluid flow variation. The intermediate section 168 is parallel to the axis 
of the gear while the end sections 170 and 172 taper slightly radially 
outwardly (about 1.degree.) away from intermediate section 168. The tapers 
are slightly exaggerated in the drawing for illustration. With this 
design, the concentricity of the gear on the shaft is controlled by the 
diameter of the intermediate section while the amount of possible rock is 
determined, for a given diametrical clearance between shaft 38 and 
intermediate section 168, by the axial length of intermediate section 168, 
tapered sections 170, 172 having sufficiently large tapers to preclude 
them from contacting the shaft. 
Driven gear 74 is similarly endowed with a limited rocking capability 
within a desired concentricity limit on stub shaft 76. However, the 
construction is somewhat different. A journal bushing 162 (FIG. 5) such as 
a molded plastic bushing of suitable plastic material, is pressed into the 
bore of the metal gear. The inner wall of the bushing is constructed with 
an intermediate axial section and tapered end sections to provide the 
rocking capability of the gear on the stub shaft within a desired 
concentricity limit. By using this construction and making stub shaft 76 
of a smaller diameter than that of the armature shaft, a common metal gear 
blank can be used for both gears 72, 74 thereby simplifying manufacturing 
operations and equipment. Such a gear blank can have a straight axial bore 
containing the axial slots 164. Bushings 162 can be pressed into the bore 
to form the driven gear. The tapers 170, 172 can be ground in a blank to 
form the drive gear. It is advantageous to form the gear blanks from 
powdered metal using existing techniques. 
The two gears are dimensioned axially for a close axial running fit within 
the pumping chamber and the capability for the gears to rock on their 
respective shafts is advantageous in securing as close a running axial fit 
as possible between the flat axial ends of the gears and the corresponding 
flat axial end walls of the pumping chamber. Where the capacity of the 
pump is to be reduced, the axial dimensions of the gears and also of the 
pumping chamber may be correspondingly reduced. In such an event it may be 
possible to eliminate the tapers while still maintaining the requisite 
degree of concentricity and of capability for rocking of the gears on 
their shafts. 
Having therefore described the details of the gears and of the pumping 
chamber, it is now appropriate to consider the manner in which the 
constituent components are assembled together to form the pump and motor 
assembly. The preferred procedure is to construct the motor assembly 32 
and assemble the interface housing member 34 thereto by means of the 
throughbolts 58a, 58b, and 58c. This having been completed, the drive gear 
72 can be keyed to the protruding end of armature shaft 38 which protrudes 
through interface housing 34. Details can be seen in FIG. 5A. A pair of 
hemispherically shaped, diametrically opposed dimples 174 have been 
provided in armature shaft 38. Gear 72 is keyed to the armature shaft for 
rotation therewith by means of ball bearings 166. The ball bearings may be 
seated in dimples 174 and kept therein by either magnetizing the bearings 
or by using a dab of lubricant. With the bearings in place, gear 72 is 
inserted onto the free end of the armature shaft with slots 164 in 
circumferential alignment with bearings 166 to lodge the latter within the 
former as the gear is more fully inserted onto the shaft. Pump housing 36a 
can now be assembled to interface housing 34a. Stub shaft 76 and driven 
gear 74 are assembled to pump housing 36a preparatory to assembling of the 
latter to interface housing 34a. The two housings 36a, 34a are axially and 
radially aligned generally with each other and are moved axially toward 
each other to a position where the free end of armature shaft 38 pilots on 
pilot hole 82 in pump housing 36a, the pilot diameters of pilot hole 82 
providing for as close a fit with the diameter of shaft 38 as practical. 
If the two gears 72, 74 are not correctly oriented for meshing engagement, 
the two elements 34a, 36a may be slightly manipulated to bring the gear 
teeth into position where they can mesh. Once this is achieved continued 
further displacement of the two elements 34a, 36a toward each other will 
cause the gears to more fully mesh and the end of shaft 38 to more fully 
engage pilot 82. It should be apparent that once the gear has been 
inserted onto the armature shaft over the ball bearings and the two 
housings brought together, it is impossible for the ball bearings to 
become dislodged from the dimples. The through-bolts 60a, 60b and 60c can 
now be tightened in appropriate holes in the interface housing 34a to 
secure the assembly together. It has been found desirable to operate the 
motor while the bolts 60a, 60b, and 60c are being tightened while 
simultaneously watching motor current on an ammeter connected with the 
leads to the motor. The bolts may be tightened in sequence until 
predetermined amperage limits are noted. This insures that the best 
possible alignment has been obtained and that tendencies for binding and 
seizing have been minimized. As the two housings 34a, 36a are being 
engaged, the sealing gaskets disposed therebetween are being compressed to 
provide appropriate sealing for the fluid connections between the two. 
This procedure establishes a close tolerance for concentricity between the 
periphery of the teeth of gear 72 and the recess 78 forming the peripheral 
wall of the pumping chamber within which gear 72 is disposed. In 
conjunction, the rocking capability of gear 72 on shaft 38 promotes the 
maximum possible parallelism between the end walls of the pumping chamber 
and the flat axial ends of the gears. Thus, because of the close control 
and tolerances and fit an efficient pump construction is achieved which 
can develop satisfactory outlet pressures, and flow quality, and which 
does not have excessive pump leakage but most importantly will provide 
minimum rotational-friction-caused speed variations, and hence minimum 
rotational-friction-caused flow variations. 
Details of the operation of the pump and motor assembly in an electronic 
fuel metering system may be obtained by referring to the above copending 
application. Briefly, the low pressure regulator valve assembly 148 
controls the pressure in vapor separation chamber 48, and hence at the 
inlet of the pumping chamber, as explained above. The pumping rate is a 
function of the motor armature shaft speed as electrically controlled. The 
outlet port is connected to a pressure regulator and fuel spray bar 
assembly and the pressure at the outlet of the pumping chamber is a 
function of the characteristics of the pressure regulator and fuel spray 
bar design. Generally, the outlet pressure increases as the pumping rate 
increases. The orifice bypass valve assembly 136 is normally closed, but 
opens in response to predetermined outlet pressures at the pumping chamber 
outlet to divert a portion of the pump output back to the tank via the 
return port. Flow through the valve must pass through an orifice and the 
proportions of fuel which is diverted is a function of the total flow 
output of the pump. Preferably, the valve assembly 136 is designed to 
close at a predetermined pressure above that at which it opened so that at 
and near maximum engine fuel demand, diversion of the pump output is 
arrested to cause the entire pump output to be fed to the engine for 
consumption. 
In actual life testing of prototype models, it has been found that 
performance and durability requirements for automotive usage are readily 
attained. Furthermore, the pump and motor assembly is compact in size and 
can be conveniently installed on an engine, as inside the air filter 
housing structure for example. Connection of external lines is facilitated 
because the ports are all located in housing 36a at one end of the 
assembly. Also, fuel handling requirements are met without the more 
complicated design of having to use a slipper type pump with its large 
number of small parts. Thus, the invention provides a compact size and 
construction which meets the functional requirements of an automotive fuel 
metering system.