Rotary fuel pump with pulse modulation

A rotary pump for pumping liquid which includes a rotor combination in the form of a vane pump or gear and rotor with pumping chambers disposed circumferentially around the rotor. The chambers progressively increase in the inlet area and ensmall in the outlet area. Pulse absorbtion means are interposed in the fuel passage means to absorb pulses and smooth out the pressurized outlet liquid, thus reducing the pump noise under all conditions of operations.

Reference is made to my copending U.S. application, Ser. No. 403,097, filed 
July 29, 1982. 
FIELD OF INVENTION 
Electric fuel pumps utilizing a rotary pump and electric drive housed 
together for mounting on a vehicle or in a vehicle fuel tank. 
BACKGROUND OF THE INVENTION 
Rotary fuel pumps driven by an electrical powering device have been 
utilized for some years in some vehicles either as original equipment or 
as appliances to supplement the original fuel supply system. The pump and 
power unit are frequently in a common housing as shown, for example, in 
U.S. Pat. No. 4,401,416, issued Aug. 30, 1982, to Charles H. Tuckey. 
Since the pumps are frequently mounted in the fuel tanks of a vehicle, the 
noise factor is extremely important. A pump under load will normally 
produce more noise and this may be audible as a humming noise, to an 
annoying degree, to passengers in the vehicle. Various pulse dampening 
devices have been tried with some success; but since they usually involve 
material such as a closed cell foam material or a hollow pulse dampening 
chamber of a synthetic flexible material, the useful life of these devices 
is limited by the vulnerability of the material in the presence of 
hydrocarbons. 
It will be appreciated that in the pumping cycle as one pumping cell is 
exhausting, another cell is taking in fluid at the same time. In other 
words, intake and exhaust pressure waves are timed with one another, and 
normally the quantity of fluid being exhausted from each cell is the same 
as that being taken in by another cell. 
It is an inherent characteristic of a positive displacement pump to produce 
slight pressure pulses each time one of the multiple vanes passes through 
its pumping cycle. For example, a roller vane rotary pump produces an 
audible humming noise when operating at system pressure. This noise has a 
tendency to increase as the output pressure requirement is increased. 
It has been a desire of manufacturers and users of positive displacement 
rotary pumps to reduce or eliminate pressure pulses in order to achieve a 
smooth, pulse-free flow of fluid out of a pump at desired operating 
pressure. 
An object of the present invention is to allow the exhaust pressure peaks 
to counter the negative inlet pressure valleys thereby cancelling one 
another and attaining a smooth flow in and out of the assembly and at the 
same time reducing the pump noise. 
This concept involves the utilization of a resilient member between the 
inlet and exhaust zones within the pump assembly. Thus, each time a 
pressure peak occurs in the exhaust fluid, the pressure can force the 
resilient member to yield or move toward the inlet fluid, thereby 
simultaneously off-setting the negative pressure which occurred at the 
same time on the inlet side. 
It has been noted that pressure waves or pulses are present at the inlet, 
as well as the outlet, at all operating pressures. 
One must acknowledge and deal with the extreme pressure differential 
between the inlet and exhaust sides of the pump. For instance, the inlet 
zone is usually at an average pressure close to atmospheric; and the 
outlet zone average pressure is much higher, i.e., 60 psi or more 
depending upon the operating pressure requirement of the pump. 
To accommodate the extreme pressure differential, a spring force can be 
applied against the resilient barrier on the low pressure side creating 
balance with the high pressure side. This allows movement of the flexible 
barrier in harmony with pressure pulses, thereby producing a smooth, 
constant flow of fluid in and out of the pump. 
Other objects of the invention will be apparent in the following 
description and claims in which the invention is described, together with 
details to enable a person skilled in the art to practice the invention 
all in connection with the best mode presently contemplated for the 
invention.

DETAILED DESCRIPTION OF THE INVENTION AND THE MANNER AND PROCESS OF USING 
IT 
Reference is made to my copending application, Ser. No. 06/557,468, filed 
12/5/1983, relating to an electric fuel pump of the same general nature as 
will be described herein. 
Referring to FIG. 1, an inlet housing 20 has a connector nipple 22 with an 
interior bore 24 terminating at the outer end in a shoulder 26 which 
serves as a seat for one end of a coil spring 30. The inlet housing 
enlarges to a radial flange 32 forming a shoulder against which is lodged 
an O-ring 34 retained in place by a turned-in end 36 of an exterior 
housing 40. This general assembly is shown and described in my U.S. Pat. 
No. 4,401,416, issued Aug. 30, 1983. 
The inner surface of flange 32 bears against a pump inlet and outlet plate 
42 with a ring disc 44 interposed and suitable sealing rings. A roller 
pump cam ring 50 is clamped between the plate 42 and a motor housing 
element 60 lying inside the outer container 40. A flux ring 62 telescopes 
over a flange 64 on element 60. Within the cam ring 50 is a roller pump 
rotor 70 driven by a shaft 72 on armature 80 of an electric motor. A 
spherical bearing 82 is journalled in element 60. 
The inlet-outlet plate 42 has an inlet passage 90 opening to an inlet 
recess 92 adjacent pump rotor 70. An outlet port 94, one of a series, 
opens to an outlet passage 96 leading to the motor housing and an outlet 
connection at the other end of the pump. A reed valve 100 is biased 
against port 94 in a manner described in detail in my copending U.S. 
application, Ser. No. 557,468, filed Dec. 5, 1983. 
The bore 24 of inlet housing enlarges to a circular recess 110. In this 
recess is a hollow modulator element or bellows 112 shown also in FIGS. 2 
and 3. The element 112 is made of thin sheet metal, preferably a stainless 
steel or phosphor bronze. A face plate 114 with a shallow spring seat 
recess 116 telescopes over a back plate 117 and is sealed at the rim in an 
air tight joint. The back plate has an axial flange 118 which is received 
in a central opening in the ring disc 44. An O-ring 120 is carried on the 
flange 118 and retained radially by a ring 122 (FIG. 1). The coil spring 
30 bears at its inner end against the modulator element 112 seated in the 
shallow recess 116. 
The O-ring seals the inner wall of the bellows 112 against the ring disc 
44, but the bellows can move outwardly against the spring 30. The interior 
of the bellows is open to the outlet pressure from port 94. Accordingly, 
the bellows may move outwardly against the spring to by-pass the pump 
output which is above the calibrated setting of the spring 30 for pressure 
by-pass to the pump inlet. 
Fluid from inlet bore 24 flows around the bellows 112 to inlet port 90 and 
thence to the roller pump. Outlet fluid under pressure passes out of port 
94 to a radial passage in plate 42 leading to passage 96 and the motor 
housing, and eventual pump outlet at the other end of the pump housing. 
The thin sheet metal from which the bellows is constructed will flex 
against the spring 30 to absorb pulses in the pump inlet and outlet, thus 
smoothing the flow from the pump. Thus, the bellows 112 serves as a pulse 
modulator and a relief valve. 
In FIG. 4, a modified structure is illustrated. Parts which are similar to 
those in FIG. 1 are marked with like reference characters. An inlet 
housing 140 has a bore with a shoulder 142 to seat one end of a coil 
spring 144. A pump cam ring 146 houses a rotor 148 of a roller pump driven 
by armature shaft 72. A pump inlet-outlet plate 150 is secured against the 
pump assembly having an inlet port 152 and an outlet recess 154 shown in 
dotted lines connected to an axially extending passage 156 leading to the 
armature housing and the ultimate pump outlet. 
The plate 150 has a first inner annular ridge 160 inside a second ridge 162 
with interruptions to provide a relief valve in conjunction with a plate 
164 backed by the coil spring 144 seated at the plate end around a button 
166. This is described in detail in my U.S. Pat. No. 4,401,416, referenced 
above. In this embodiment an annular bellows element 180 is mounted on 
shaft 72 between the armature 80 and the ball mount 82. The bellows, as 
illustrated in FIGS. 5 and 6, is formed from thin metal such as stainless 
steel or phosphor bronze to provide flexible walls. The bellows is a 
torus-shaped element formed of two annular sheets telescoped together at 
the inner and outer diameters 182 and 184. These joints are sealed to 
provide an air tight annular chamber 186. The element 180 is shaped to 
have annular bulges 188 and 190 with flat annular walls in between. These 
walls will flex in and out with the pulses of the pump output so that the 
output flow will be modulated into a relatively smooth flow. 
In FIGS. 7 and 8, another modification is illustrated. An inlet housing 200 
has a shoulder 202 to provide a spring seat for coil spring 204. A pump 
cam ring plate 206 has a rotor recess housing a roller rotor 210 driven by 
shaft 72 on which it is mounted. An inlet-outlet plate 220, facing against 
the pump assembly 206, 210, has an inlet port 222 leading to the pumping 
recesses of the pump assembly and a series of outlet ports 224, 226, 228 
and 230 (FIG. 8). These ports open to a recess 232 and an axial outlet 
passage 234 in communication with the armature chamber and the ultimate 
pump outlet. 
The ports 226, 228 and 230 are closed by a three-fingered reed valve leaf 
240 held against plate 220 by a headed screw 241 in a disc 242. A finger 
extension 244 stabilizes the reed valve leaf in proper orientation. The 
function of this assembly is fully described in my copending application, 
above referenced. The reed valve 100 in FIG. 1 is like that shown in FIG. 
8. In general, the flexible fingers 246, 248 and 250 overlying ports 226, 
228 and 230 allow outlet flow under pressure but in the event of 
cavitation (vapor formation) due to high ambient temperatures, the fingers 
prevent impacting backflow into the pump recesses which is a source of 
noise in pump operation. 
An additional modulator plate 260 is interposed between the flange 262 of 
inlet housing 200 and the inlet-outlet plate 220. This plate 260 has a 
flat outer edge rim 264 and an inner central portion which curves 
outwardly and terminates in a central hole 266. A cup 268 in hole 266 
provides a seat for the inner end of coil spring 204. 
A modulator sheet 270 has a central flat portion 272 lying against the 
bottom of cup 268. The sheet 270 is clamped at its peripheral edges 
between flange 262 and plate 220. The plate 270 is made of a thin flexible 
material such as stainless steel or phosphor bronze so that the center 
portion can flex in response to outlet pressure of the pump. The disc 242 
provides an inner stop surface. The chamber 271 between sheet 270 and 
modulator plate 260 is hermetically sealed. 
Also, in FIG. 7, a toroidal pulse modulator is mounted on shaft 72 adjacent 
the armature as shown in FIG. 4 and described in connection therewith. 
In the operation of the embodiment of FIGS. 7 and 8, the flexing of the 
pulse modulator sheet 270 serves to absorb and smooth out the pulsing 
outlet of the positive displacement pump assembly. The toroidal modulator 
180 in the armature chamber also functions in the same way as previously 
described to reduce pulsations and provide a commensurate reduction in the 
noise and vibration of the pump. 
The preferred material for the pulsing elements has been described as 
preferably formed of thin stainless steel or phosphor bronze. This 
material has sufficient flexibility and long life and is fully resistant 
to the hydrocarbon fuel. A dense plastic such as Nylon or Teflon might be 
substituted for some applications.