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Dec. 117, 1946.
2,412,835 :
Filed Nov‘. 29,‘ 1940
40 4a
Patented Dec. 17,1946
, ‘2,412,835
vrowan pgz?ihssrtis
James Robinson, Detroit, Mich; assignor
Vickers Incorporated, Detroit, Mioh._, _a corpo
ration of Michigan
Application November 29, 1940, seem No. scares
50laims. (oi. 103-162)‘ _
‘This invention relates to power transmissions,
particularly to’ those of the type comprising two
venting seepage of air'into
the working circui -
of a wet casing type pump.
or more ?uid pressure energy translating devices, A further object is to Provide an improved
one of which may function as a pump and an
and method for initially ?lling the casing
other as a ?uid motor.
of a pump of this character.
The invention is more particularly concerned’
_ Further objects and advantages of the present
with a fluid pressure energy translating device ‘ invention will be apparent from the. following
adapted to function as a pump or motor in an
description, reference being had to the accom
open-circuit type of power transmission system
and particularly suited for high speed operation.
In'systems of‘ this character, particularly those of
smaller size, which are capable of operating at
panying drawing wherein a preferred form of the
present invention is clearly shown.
_ '
In the drawing:
Figure l is a longitudinal sectional view of ‘a
speeds of several thousand revolutions per min
wet case pump embodying a preferred form of
ute, considerable trouble has been encountered
the present invention.
with air‘ getting into the working circuit and the 15, ' Figure 2 is a fragmentary sectional view taken
well-knownv attendant di?iculties arising when
on linev 2-2 of Figure 1 and showing diagram
this occurs. The term “pump” is used hereafter
matically a conventional open-circuit type of
inthe speci?cation and claims as embracing both
power transmission system in which the pump is '
a pump and a ?uid motor.
_ .
Pumps of the typehaving a. wet case, that is, 20 Referring now to Figure'l, the pump com
one which is normally ?lled with substantially
prises two tubular casing members it and i2 dis
' idle power transmission liquid, utilize the casing
posed at an angle relative to one another, ‘the
, as a means-for collecting the ?uid leaking past
member‘ I 0 carrying anti-friction bearings II on
the piston and valve mechanism and for return
which a ?anged drive shaft It is mounted. An
ing it to the expansion tank provided in the cus
oil seal l8 closes the righthand end of the casing
tomary open-circuit system. It is frequently de
It. The shaft. I6 is adapted to be driven by the ,
sirable to locate the pump-at a considerable dis
I tance from the expansion tank as, for example,‘
aboard aircraft where the pump may be located
shaft of a suitable primemover indicated at 20
and which is spline-connected to the ?anged
shaft II."
- at ‘a wing-mounted engine of the plane and the so The righthand end of the shaft It carries a
expansion tank positioned at some convenient re
?ange 22 which is provided with a plurality of
mote place in the fuselage. In such cases it is un
. desirable to run a separate casing drain line he
ball Joints 24 by which piston rods 26 are articu
lated to the ?ange 22. At their opposite ends the
‘ tween the casing and the ‘expansion tank so that
piston rods 26 carry ball-Jointed pistons 28 recip
resort‘is had‘ to usingithe pump suction line for 35 rocable in cylinder bores 80. The latter are
both feeding the inlet of the pump and for receiv
formed in a cylinder barrel 32 which is jour
ing excess leakage ?uid from the pump casing.
nalied on an anti-friction bearing 34 carried by a
Where systems of this character are operated
hollow stub shaft 88." The-latter
to a
at high speed, as they‘usually are in aircraft; in M ‘valve .plate block 38 which in turnisissecured
secured to
stallations, considerable di?lculty, has~been ex 40 the open end of easing member If. A Cardan
perienced in keeping air out of the working cir
shaft 40, having universal joints 4! at its op
cuit. ,' Applicant has found that with systems of
posite ends, connects the cylinder barrel 32 to the
this character it occasionally happens that, due
to the resistance of the pump suction line, the -
shaft it for conjoint rotation therewith. -
The valve plate is provided with-the usual an- '
pressure therein is reduced below atmospheric by 45. nuiar
valving surface it having a pair of arcuate
1 the high speed operation of the pump, and as a
consequence the interior of the Dump' casing is '
correspondingly subjected to negative pressure.
. ports 46 and 48 formed therein and communi
eating with pressure and suction-connections Il'
and 82. ,The Cardan shaft 40 is urged to the left ,
This premits air to badrawn into the pump cas
a spherical abutment block It by. a
ing through the oil seal at‘the shaft, and since 50 against
spring-pressed abutment block it at its right
the casing is connected to the pump, suction line,
end.‘ The cylinder_ barrel" is urged into
such air is eventually delivered to the working : handv
contact with the‘ valve plate 38 by a spring 58I
circuit or the pump. '
y .
which is positioned between ‘the bearing 34 and '
1 It is an object of the present invention to pro
‘I at the lefthand side of the block 32.
vide an improved means and method for pre
'For the purpose of preventing drawing in of air I
on, the leakage liquid will begin ?owing through
to the interior of the pump casing there is pro
the outlet path and continue so to ?ow as long as
vided an outlet path for the leakage oil which is
' constantly being fed into the interior of the eas
ing at a slow rate by leakage between the valve .
the pump keeps operating.
valve ‘l0, anynegative pressure created in suc
tion port 62 by high speed operation and by the
resistance of conduit 82 can never reach the in
- teriorof the casing l2 so that, in order for oil
to escape from the casing, it must build up ‘a
pressure su?lcient to overcome relief valve ‘Hi.
This pr'essure'is, of course, builtnp by the con
64 in the Cardan shaft 48. This passage in turn '
communicates with a passage 68 in the block 84
which communicates with the hollow interior of
tinuing ?ow ofleakage oil into the casing which,
stub shaft 86. The latter is also provided with
though small, is nevertheless incessant and re
quires a path for escape-‘or it will buildup tre
cross bores 68 which receive leakage ?owing radi- :
ally inward across the pressure surface’ 44 of the
< '
- Due to the back pressure maintained by relief
plate and cylinder barrel as well as leakage past
the piston 28. The outlet provided for this oil comprises a cross bore~62 formed in the block 88
and communicating with a longitudinal passage
valve plate 88.
mendous pressure. In this manner the pressure
in the casing will be maintained slightly positive
or above atmospheric so that the pressure on the
lightspring 12. The spring abutment block 14 f lefthand side of oil seal I8 is always above that
on the righthand side. This insures that no air
andv the stub shaft 86 are locked to the valve
' will be drawn in through the seal and that a
plate 88 by a pin 16 which is accessible by a pipe
small seepage will take place through the seal
plug 18.‘ The relief valve 18‘ discharges through
suilicient to keep thelatter lubricated and pre
an angular cross bore 88 which communicates
vent its burning at the high speeds of operation
with the suction port 52. Y
Mounted in the lefthand end of the hollow stub
shaft 36 is a relief valve ‘III which is backed by a
customarily encountered.
. The pump described may be connected in the.
While the form of embodiment of the invention
usual open-circuit hydraulic ‘power transmission
as herein disclosed constitutes a preferred form,
it is to be understood that other forms might\be
adopted, all coming within the scope of the
system as illustrated in Figure 2. Thus the suc
tion port 52 is connected by a suction conduit 82 .
with the usual expansion tank 84. The ‘delivery
claims which follow.
' connection 68 connects by means of a conduit 88
having a ?lling and air-bleed valve 88 at a high 30
point therein with the pressure port of a con
ventional four-way valve 98. The latter has its
What is claimed is‘ as follows:
1. In a reciprocating piston pump of the type
having a sealed casing of ?xed liquid volume and
having separate suction and delivery portsthe
tank port connected by a conduit 92 with the
combination of means forming a connection be
tank 84 and its cylinder ports connected by con
duits 84 and 86 with the opposite ends of a ?uid 35 tween the casing and the suction port of the
pump and constituting the'sole exit from the eas
ing and a pressureresponsive valve in said con
nection adapted to con?ne all leakage ?uid to
with oil in the‘ customary manner through the
the casing until a predetermined positive pres
valve 88 after which the pump may be placed in
operation withdrawing oil from the tank 84 40 sure is reached in the casing, said connection
leading from a point near the center of revolu
through the suction conduit 82 and delivering ‘it’
tion of the pump parts whereby all air originally
from delivery port 58 through pressure conduit
motor 98.
‘In operation,‘ the working circuit may be ?lled
present in the casing will be discharged from the‘
88. r customarily the valve 88 is left in neutral
delivery port duringvinitial operation of the
‘position in which the pump is bypassed, and
the pump is operated for some time until-the air 45 pump.
2. In a reciprocating piston‘ pump of the type '
has been completely removed from the system as
having a sealed casing of ?xed liquid volume and
evidenced by the inability to bleed air from the
pressure line 86' when valve 88 is cracked open. '
During this operationv of the pump, any air origi- I
nally present inthe pump‘ casing will be trans
ferred to the working circuit in the following
50 bination of an outlet constituting the sole exit
As leakage occurs from the working circuit to
the interior of thefcasing, the body of liquid is
gradually built up therein which at ?rst, by its ,
mere presence in the casing, tends to displacelair
out through the outlet path beginning at the pas
sage 62 until the relief valve 10 is reached. ‘ As
having separate suction and delivery ports and
rotating working parts disposed within and dis
charging leakage ?uid into the casing the com
from said casing and communicating with‘said
suction port and a pressure responsive valve in
said outlet for maintaining a slight positive pres
sure in said casing.
3. In a reciprocating piston pump of the type
having a sealed casing of ?xed liquid volume and
having separate suction and delivery ports and
more and more liquid ‘enters the casing, this
a rotary cylinder barrel journalled on a hollow
It will be seen that noliquid can escapethrough
having a sealed casing of ?xed liquid volume and
pin mounted on‘ a wall of saidcasing, the com
liquid will-be churned around by the revolving
bination of means forming a connection between
parts setting up a centrifugal action keeping the
the casing and,’ the suction port of the pump and
.liquid in the‘ radially outermost portion of the
' including said hollow pin as a part thereof and
casing and pocketing any air present in the cen
a pressure responsive valve in said hollow pin
traP portion of the casing. As the liquid con,
tinues to enter the casing, the pressure builds up 65 adapted to con?ne all leakage ?uid to the casing
until a predetermined positive’ pressure is reached
until the relief valve 10 opens, at which time a
in the casing.
small ?ow takes place continuously through the
4. In a reciprocating piston pump of the type
relief valve and passage 88 to the suction port 52.
this path until all the vair in the casing has‘been 70 having separate suction and ‘delivery ports and
having a rotary cylinder barrel provided with a
displaced since; due to the different densities of
plurality of axially disposed cylinder bores dis
the liquid and the air, the centrifugal force will ,
maintain the liquid in the outer part of the eas
' posed within and discharging leakage ?uid into
the casing, the combination of an outlet consti
through the outlet passage 62. From this point 76 tuting the sole exit from said casing and com
_ ing until all ’of ,theair. has been forced out’
municating with said suction port and a pressure
said casing and communicating with said suc
responsive valve in said outlet for maintaining a
tion port and a pressure responsive valve in said
slight positive pressure in said casing.
outlet for maintaining a slight positive pressure
5. In a reciprocating piston pump of the type
in said casing. Said outlet leading from a point
having a sealed casing of fixed liquid volume and 5 adjacent the center of rotation of the barrel
having separate suction and delivery ports and
whereby any air present in the casing is forced
having a rotary cylinder barrel provided with a
to said outlet by centrifugal force in conjunction
plurality of axially disposed cylinder bores dis
posed within and discharging leakage ?uid into
the casing, the combination of a single outlet from 10
with the pressure built up by the leakage ?uid
against said valve.
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