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Патент USA US2406973

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Sepf» 3,1946'
M. A. 'rRlsLER
Filed Nov. 2'7,
1942 ì ‘
Patented Sept. 3, 1946
Milton A. Trisler, Indianapolis, Ind., assignor to
General Motors Corporation, Detroit, Mich., a
corporation of Delaware
Application November 27, 1942, Serial No. 467,134
5 Claims.
(Cl. 10B-_42)
An improvement in a pump serving to supply
fuel to the engine of an airplane constitutes the
subject matter of this invention.
The object of the invention is to provide for
maintaining substantially constant absolute pres~
sure, regardless of altitude, on the bypass valve
phragm and valve, being operable to bias the
valve upon its seat.
The operation of the device is as follows.
is important that the absolute fuel pressure for
the carburetor should be substantially constant
-or should not fall 01T in proportion to the de
or other pressure regulating mechanism of an
crease of atmospheric pressure with increases in
airplane fuel pump. Other objects such as sim
altitudes. To provide for all needs the pump ca
plicity and eiiiciency will be understood from the
pacity must be such that the pump outlet pres
description which follows.
10 sure always tends to exceed the desired carbu
retor pressure. In consequence the bypass valve
An embodiment of the invention is shown by
the accompanying drawing in which:
is at all times open, at least to some extent.
Figure l is a transverse section through a fuel
The pressure at the pump outlet in excess of the
pump combined with a bypass and having my im
constant pressure needed opens the valve, the
provement incorporated therein.
underside of the diaphragm (which is greater in
Figure 2 is a section on line 2-2 of Figure 1.
area than the bypass valve) being always in com
munication with the pump outlet by way of pas
On the drawing, numeral 5 is used to identify
a pump housing. It has an inlet 9 to receive
sages 4'I, 45 and 43. 'I’h'e fuel returns to the low
pressure side of the pump by way of passage 49
The constant pressure desired is main
fuel from a suitable source and an outlet ‘I for
connection to the carburetor. Between the inlet
and outlet is a pump barrel II within which is
an eccentric rotor I3 -carrying the blades I5 and
spacing roller I1 as in prior pumps. Above th'e
housing 5 is a bypass Valve support I9 and above
part I9 is a dome-shaped cover 2|, fastening
means 23 securing the several parts together as
Part I9 has an upper transverse but apertured
wall 25, an intermediate transverse partition 21,
and a circular inner tubular part 2S which latter
is reduced in diameter at 3l to telescope within
a similar sleeve part 33 of body 5. Between
pump parts IS and 2| is secured a flexible dia
phragm 35. On the under side of the diaphragm
is a flanged disc 3'! integral with a tapered wall
valve member 39 which engages a valve seat 4I
on part 23. When the valve is seated the space
above th'e valve and partition 2T is in communi
cation with the discharge side of the pump by
a passage ¿i3 in the partitionizl and registering
passages 45 and 41 in the pump members I9 and
5 respectively. The tubular part 29 is cut away
to form an opening 49 by which the space within
20 and 53.
tained by the proper adjustment at 51 of springs
6I .
At sea level the tendency of the sealed evac
uated bellows to expand and exert pressure on
the valve is partially balanced by the external
25 pressure on the bellows. When the device is
used on an airplane, and the apparatus reaches
higher elevations the reduced external air pres
sure permits the bellows spring 6I to exert in
creased pressure on the valve to maintain the
30 pressure applied to the diaphragm and valve sub
stantially constant. In the absence vof the bel
lows, the pressure on the valve being the air pres
sure plus the spring pressure, would decrease as
the plane reaches higher altitudes and with de
creasing applied pressure the valve would open at
too low pump pressures and insuñicient fuel
would be supplied to the carburetor.
It will be
observed that the diaphragm 35 performs the
important function of preventing the fuel under
th‘e pressure conditions determined by the pump
from reaching the space around the bellows with
the result that the unbalance of air pressures is
free to operate as stated.
said part 29 is in communication through regis
I claim:
1. In a fuel pump having a pressure regulator
tering passages 5I and 53 in parts I9 and 5 with 45
the low pressure (intake) side of the pump, the
by~pass, a valve therefor, a spring and an alti
side leading from the fuel supply.
tude sensitive aneroid jointly Operable on said
The part 2| of th'e assembly is open to the at
valve, an air vented chamber containing said
spring and aneroid and a flexible diaphragm con
mosphere at 55. A threaded member 51 in its
upper face adjustably positions the upper abut
nected to said valve and separating said aneroid
chamber from said bypass the dimensions of the
ment 59 of a spring 6I. A sealed bellows or
aneroid and the diaphragm being such that th‘e
aneroid 63 of known construction is secured to
air pressure within the chamber exerts a force
abutment 59. Its lower end contacts the dia
on the diaphragm tending to close the valve sub
phragm 35. Spring El is within the bellows and
exerts pressure on its lower face and on the dia 55 stantially equal to the force of said air pressure
to exert thereon variable pressures dependent
acting on the aneroid in a direction t0 open the
2. In a fuel pump, means forming a bypass
between the high pressure and low pressure sides
of said pump, a valve to close said bypass, a
force applied by said spring.
spring and an altitude sensitivel aneroid operable
jointly to bias said valve to closed position, an
sure regulating by-pass valve, means forming a
upon external air pressure.
4. The invention deñned by claim 2, together
with adjustable means to determine the resilient
5. In combination, a fuel pump having a pres
chamber associated with said fuel pump, mov
air vented chamber containing said aneroid, and
a. diaphragm sealing said ch'amber from said by-` 10 able means secured to said valve and separating
said pump from said chamber, said chamber be
pass the dimensions of the aneroid and the dia
ing open to the surrounding air, a sealed aneroid
phragm being such that the air pressure within
and a spring within said chamber and jointly
the chamber exerts a force on the diaphragm
operable on said movable means, the dimensions
tending to close the valve substantially equal, ‘5.0
the force of said air pressure acting on the
aneroid in a direction to open the valve.
3. The invention defined by claim 2, said
aneroid comprising a sealed and partially evacu;
of the aneroid and the movable means being such
that the air pressure with'in the chamber exerts
a force on the movable member tending to close
the valve substantially equal to the force of said
air acting on the aneroid in a direction to open
ated bellows having a fixed abutment, at one end,
the valve.
th'e other end operably associated with said valve 20
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