FLUID SUPPLY SYSTEM

SYSTEME D'ALIMENTATION EN FLUIDE

English Abstract

FLUID SUPPLY SYSTEM
Abstract of the D closure
A fluid supply system includes a pump body having a main
bore connectible through inlet check valves to draw secondary
fluid from a first fluid reservoir and through outlet check
valves to supply it to a secondary fluid function upon recipro-
cation of a free piston in the main bore. The free piston in-
cludes a pair of coaxial driving pistons on either side which
extend into main passages which are alternately connected to a
pressurized primary fluid source to cause reciprocation of the
free piston. A first spool valve which responds to the comple-
tion of a free piston stroke activates a second spool valve which
changes the primary fluid source connections to the driving
pistons.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A secondary fluid supply system connectible to a fluid
source of primary fluid, a fluid reservoir of secondary fluid,
and a secondary fluid function, said secondary fluid supply
system comprising:
a) a secondary fluid pump;
b) a cylinder enclosed in said secondary fluid pump having
first and second check means, said first check means disposed
proximate an end of said cylinder for fluidly connecting said
fluid reservoir to said cylinder, and said second check means
disposed proximate said end of said cylinder for fluidly connect-
ing said cylinder to said secondary fluid pressure function;
c) free piston means disposed in said cylinder movable
between first and second positions therein to draw secondary
fluid from said fluid reservoir through said first check means
and to supply secondary fluid to said secondary fluid pressure
function through said second check means, said free piston means
having first and second driving means operatively connected
thereto respectively responsive to connection to said fluid
source to move said free piston means between said first and
second positions, said fluid pump including first and second :
sealing means respectively operatively associated with said first
and second driving means for sealing said primary fluid connected
thereto from said secondary fluid in said cylinder; and
d) first and second interconnected valve means connecting
said fluid source to said first and second driving means, said
first valve means responsive respectively to the connection of
said primary fluid from said fluid source to said first and
second driving means to said free piston means in the respective
second and first positions for causing said second valve means to
respectively connect said primary fluid from said fluid source to
said second and first driving means.

2. A secondary fluid supply system connectible to a fluid
source of a primary fluid, a fluid reservoir of a secondary
fluid, and a secondary fluid function, said secondary fluid
supply system comprising:
a) a secondary fluid pump;
b) a cylinder enclosed in said secondary fluid pump having
first and second check means, said first check means disposed at
opposite ends of said cylinder for connection to said fluid
reservoir to allow entrance of secondary fluid to said cylinder
therefrom, and said second check means disposed at said opposite
ends of said cylinder for connection to said secondary fluid
pressure function to allow exit of secondary fluid from said
cylinder thereto;
c) free piston means disposed in said cylinder movable
between first and second positions therein to draw secondary
fluid from said fluid reservoir through said first check means
and to supply secondary fluid to said secondary fluid pressure
function through said second check means, said free piston means
having first and second driving means operatively connected
thereto respectively responsive to connection to said fluid
source to move said free piston means between said first and
second positions, said fluid pump including first and second
sealing means respectively operatively associated with said first
and second driving means for sealing said primary fluid connected
thereto from said secondary fluid in said cylinder; and
d) first and second interconnected valve means connecting
said fluid source to said first and second driving means, said
first valve means responsive respectively to the connection of
said primary fluid source to said first and second driving means
and said free piston means in the respective second and first
positions to cause said second valve means to respectively
connect said primary fluid from said fluid source to said second
and first driving means.

3. A secondary fluid supply system connectible to a source
of primary fluid, a first fluid reservoir of primary fluid, a
second fluid reservoir of secondary fluid, and a secondary fluid
function, said secondary fluid supply system comprising:
a) a pump body;
b) a main bore enclosed within said pump body having first
and second ends;
c) first and second bores enclosed within said pump body
having respective first and second ends;
d) an inlet into said pump body connecting said source of
primary fluid to said first and second bores between said respec-
tive first and second ends thereof;
e) first and second pilot passages enclosed within said
pump body respectively connecting said first bore proximate said
first end to said second end of said second bore, and said first
bore proximate said second end to said first end of said second
bore;
f) first and second main passages enclosed within said
pump body respectively connecting said second bore proximate said
first end to said first end of said main bore, and connecting
said second bore proximate said second end to said second end of
said main bore;
g) first and second control passages enclosed within said
pump body respectively connecting said first and second ends of
said first bore to said first and second main passages approxi-
mately at said ends of said main bore;
h) first and second relief passages enclosed within said
pump body respectively connecting said first ends of said first
and second bores to said first main passage between said first
control passage and said first end of said main bore and said
second ends of said first and second bores to said second main
passage between said second control passage and said second end
of said main bore;

i) a secondary fluid reservoir passage enclosed within
said pump body connecting said second fluid reservoir to both
said first and second ends of said main bore;
j) a secondary fluid passage enclosed within said pump
body connecting said secondary fluid pressure function to both
said first and second ends of said main bore;
k) first and second reservoir check valve means respec-
tively disposed in said reservoir passage proximate said first
and second ends of said main bore for preventing secondary fluid
from flowing from said main bore into said reservoir passage;
l) third and fourth check valve means respectively dis-
posed in said secondary fluid pressure function passage proximate
said first and second ends of said main bore for preventing
secondary fluid from flowing from said secondary fluid pressure
function into said main bore;
m) first spool means positioned within said first bore and
extending into both said first and second control passages, said
first spool means movable in response to primary fluid in said
second control passage to connect said primary fluid from said
source to said second pilot passage and said second relief
passage to said first pilot passage and in said first control
passage to connect said primary fluid from said source to said
first pilot passage and said second relief passage to said second
pilot passage;
n) second spool means positioned within said second bore
and extending into both said first and second pilot passages,
said second spool means movable in response to primary fluid in
said second pilot passage to connect said source to said first
main passage and said second relief passage to said second main
passage and to primary fluid in said first pilot passage to
connect said source to sald second main passage and said first
relief passage to said first main passage; and

o) free piston means positioned within said main bore and
extending into said first and second main passages, said free
piston means for responding to high pressure primary fluid in
said first main passage to move from a first position connecting
said first and second control passages to said first fluid
reservoir and said second bore through a series of positions
drawing fluid from said reservoir through said first reservoir
check valve means and supplying fluid from said main bore through
said second outlet check valve means while respectively blocking
said first and second control passages from said first and second
main passages to a second position respectively connecting said
first and second control passages to said second bore and said
first fluid reservoir, said free piston means responsive to
primary fluid in said second main passage to move from said
second posit-on through a series of positions drawing fluid from
said reservoir through said second reservoir check valve means
and supplying fluid from said main bore through said first outlet
check valve means to said first position.
4. The secondary fluid supply system of claim 3 wherein
first and second sealing means are positioned between said first
and second main passages and said first and second ends of said
main bore respectively for sealing said primary fluid from said
secondary fluid.
5. A secondary fluid supply system connectible to a
primary fluid pump, a first fluid reservoir of primary fluid, a
second fluid reservoir of secondary fluid, and a secondary fluid
function, said secondary fluid supply system comprising:
a) a pump body;
b) a cylindrical main bore enclosed within said pump body
having first and second ends;
c) first and second bores enclosed within said pump body
having respective first and second ends;
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d) a primary fluid inlet into said pump body connecting
said primary fluid pump to said first and second bores medially
between said respective first and second ends thereof;
e) first and second pilot passages enclosed within said
pump body respectively connecting said first bore between said
primary fluid inlet and said second relief passage to said first
end of said second bore and said first bore between said primary
fluid inlet and said first relief passage to said second end of
said second bore;
f) first and second main passages enclosed within said
pump body respectively connecting said second bore between said
primary fluid inlet and said first relief passage to said first
end of said main bore and said second bore between said primary
fluid inlet and said second relief passage to said second end of
said main bore;
g) first and second control passages enclosed within said
pump body respectively connecting said first and second ends of
said first bore to said first and second main passages respec-
tively proximate said first and second ends of said main bore;
h) first and second relief passages enclosed within said
pump body respectively connecting said first ends of said first
and second bores to a first main passage between a first control
passage and said first end of said main bore and said second ends
of said first and second bores to a second main passage between a
second control passage and said second end of said main bore;
i) a reservoir passage enclosed within said pump body
connectible to said second fluid reservoir;
j) a secondary fluid outlet passage enclosed within said
pump body connectible to said secondary fluid function;
k) first and second reservoir check valves respectively
connecting said reservoir passage to said first and second ends
of said main bore and allowing secondary fluid into said main
bore;
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l) third and fourth check valves respectively connecting
said secondary fluid outlet passage to said first and second ends
of said main bore and allowing secondary fluid out of said main
bore;
m) a first spool slidably positioned within said first
bore and having first and second ends, said first spool having
first and second pilot pistons respectively extending from said
first and second ends and respectively extending into said first
and second control passages to move said first spool to a first
position when said first and second control passages are respec-
tively connected to said primary fluid pump and said main bore
and to a second position when said first and second control
passages are respectively connected to said second ends of said
first and second bores to a second main passage between a second
control passage and said second end of said main bore;
n) second spool means positioned within said second bore
and extending into both said first and second pilot passages,
said second spool means movable in response to primary fluid in
said second pilot passage to connect said source to said first
main passage and said second relief passage to said second main
passage and to primary fluid in said first pilot passage to
connect said source to said second main passage and said first
relief passage to said first main passage; and
o) free piston means positioned within said main bore and
extending into said first and second main passages, said free
piston means for responding to high pressure primary fluid in
said first main passage to move from a first position connecting
said first and second control passages to said first fluid reser-
voir and said second bore through a series of positions drawing
fluid from said reservoir through said first reservoir check
valve means and supplying fluid from said main bore through said
second outlet check valve means while respectively blocking said
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first and second control passages from said first and second main
passages to a second position respectively connecting said first
and second control passages to said second bore and said first
fluid reservoir, said free piston means responsive to primary
fluid in said second main passage to move from said second posi-
tion through a series of positions drawing fluid from said reser-
voir through said second reservoir check valve means and supply-
ing fluid from said main bore through said first outlet check
valve means to said first position.
6. The secondary fluid supply system of claim 5 wherein
first and second sealing means are positioned between said first
and second main passages and said first and second ends of said
main bore respectively for sealingly encircling said first and
second driving pistons.
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Description

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FLUID SI~PPLY SYSTEM
The present invention relates generally to secondary fluid
supply pumps and more particularly to a hydraulically driven,
pressure compensated, self-priming, low-pressure freon supply
pump,
In the past, cornplex and expensive pumps were required to
obtain pressure compensated, self-priming, two fluid operation
and attempts to make direct pressure-operated reciprocating
piston pumps were frustrated by the incompressibility of hydraulic
fluid which would prevent totally bi-stable operation of the free
piston.
Summary of the invention
The present invention provides a simpler primary fluid
driven, pressure compensated, self-priming, secondary fluid
supply system.
The above and addi-tional advantages of the present invention
will become apparent to those skilled in the art from a reading
of the following detailed description when taken in conjunction
:
with the accompanying drawing.
` 20 Brief Descri~tion of the Drawing
The drawing is a schematic, partially in section, incorporat-
ing the preferred embodiment of the present invention.
Description of the Preferred Embodiment
:
Referring now to the drawing, therein is shown a fluid
`- supply system 10 including a primary fluid pump 12 drawing primary
fluid from a first fluid reservoir 14 and pressurizing it to
supply a primary fluid inlet 16 in a pump body 18. In the pre- i~
ferred embodiment, the primary fluid is hydraulic oil.
; The pump body 18 further contains a reservoir passage 20
which is connected so as to allow the drawing of a secondary ~
fluid from a second fluid reservoir 21 and a secondary fluid `
outlet passage 22 which is connected so as to allow the supplying
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1 of the secondary fluid to a conventional secondary fluid function,
generally designated 24, which, with freon as the secondary
fluid, would be an air conditioning system.
Referring back to the primary fluid inlet 16 and utilizing a
convention wherein the right and left hand sides of the pump body
18 are respectively on the right and left hand sides of the
viewer, the primary fluid inlet 16 is medially connected to first
and second bores 26 and 28 in first and second five-way valves 30
and 32, respectively.
The first bore 26 has ports immediately adjacent to the left
and right of the primary fluid inlet 16 which are respectively
connected to right and left pilot passages 34 and 36 and which,
in turn, are directly connected to the right and left ends,
respectively, of the second bore 28. Right and left relief
passages 38 and 40 are respectively connected to the right and
left ends of the first bore 26 as well as the right and left ends
respectively of the second bore 28. The relief passages are
interconnected and relieve to the first reservoir 14.
A cylindrical main bore 42 is provided in the pump body 18
and is connected to right and left inlet check valves 44 and 46
; which allow the flow of fluid from the second reservoir 21 and
the reservoir passage 20 into the main bore 42. The right and
left inlet check valves 44 and 46 are respectively adjacent to
right and left outlet check valves 48 and 50 which allow the
passage of secondary fluid from the main bore 42 into the second-
ary fluid outlet passage 22.
Coaxial with the main bore 42 are portions of right and left
main passages 52 a:nd 54 which are connected to the second bore 28
respectively to thle right and left of the primary fluid inlet 16.
Further connected to the right and left main passages 52 and
54 are right and l~eft control passages 56 and 58 which are con-
nected to the right and left ends respectively of the first bore
.
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1 26. The ri~ht and left relief passages 38 and 40 are respec-
tively connected to the right and left main passages 52 and 54
between the right and left control passages 56 and 58.
The first valve 30 includes a first spool 60 which has right
and left lands 62 and 64 and right and left pilot pistons 66 and
68 which are slidable in coaxial portions of the right and left
control passages 56 and 58, respect1vely. The first spool 60 is '.
shiftable from a right position (~as shown) in which the primary
fluid inlet 16 is connected to the left pilot passage 36 and the
left relief passage 40 is connected to the right pilot passage 34
to a second position in which the first spool 60 connects the
: primary fluid inlet 16 to the right pilot passage 34 and the
right relief passage 38 to the left pilot passage 36.
The second valve 32 includes a second spool 70 which has
right and left lands 72 and 74 and right and left pilot pistons
76 and 78 which extend into coaxial portions of the right and
left pilot passages 34 and 36, respectively. The second spool 70
is movable between a right position ~as shown) in which the
primary fluid inlet 16 is connected to the right main passage 52
and the left relief passage 40 is connected to the left main
passage 54 to a left position in which the primary fluid inlet 16
is connected to the left main passage 54 and the right relief
passage 38 is connected to the right main passage 52.
The main bore 42 is part of a secondary fluid pump 80 which
includes a free piston 82 which is sealingly slidable in the main
bore 42. The free piston 82 includes right and left driving
pistons 84 and 86 which extend into the coaxial portions of the ~ -
right and left main passages 52 and 54, respectively. Between --
the coaxial portions of the right and left main passages 52 and
54 and the main bore 42 are right and left seal assemblies 85 and
87 which respectively encircle the right and left driving pistons
84 and 86 to prevent the mixing of the primary and secondary
- . - .... . .. . . . . :

1 fluids. The right and left seal assemblies are respectively
relieved to the right and le~t relief passages 38 and 40 by
passages 89 and 91. The right and left driving pistons 84 and 86
are respectively provided with reliefs 88 and 90. The free
piston 82 is movable from a right position where it abuts a stop
92 to a left position where it abuts a stop 94.
In operation, the fluid supply system 10 may be started at
any position of the free piston 82 upon application of pressurized
primary fluid from the primary fluid pump 12 to the primary fluid
inlet 16 because the first and second valves 30 and 32 ensure bi-
stable operation.
Starting from the position shown in the drawing, pressurized
fluid in the primary fluid inlet 16 is supplied to the left pilot
passage 36 by the first valve 30 which causes the second valve 32
to cause pressurized fluid from the primary fluid inlet 16 to
pressurize the right main passage 52. Pressurization of the
right main passage 52 causes the right driving piston 84 to start
moving the free piston 82 to the left.
Leftward movement of the free piston 82 causes the left
inlet check valve 44 to open to draw secondary fluid into the
main bore 42. Simultaneously, the outlet check valve 50 is
opened to allow secondary fluid in the main bore 42 to exit to
the secondary fluid function 24. As would be evident to those
skilled in the art, with proper sealing between the free piston
82 and the main bore 42, the secondary fluid pump 80 will be
self-priming.
With the free piston 82 moving to the left, it will be noted
in this position that the left control passage 58, the left main
passage 54, and the right pilot passage 34 are all connected to
the left relief passage 40 and thence to the first reservoir 14.
Also, it will be seen that the right control passage 56 is connec-
ted by the relief 88 to the first reservoir 14.

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1 As the free piston 82 continues to the left, the right
driving piston 84 will allow fluid communication be-tween the
pressurized right main passage 52 and the right control passage
56. However, since the left driving piston 86 will block the
left control passage 58, movement of the first spool 60 will be
prevented and subsequently movement of the second spool 70 will
also be prevented.
When the free piston 82 reaches a position proximate the
second stop 94, the left control passage 58 will be placed in
fluid communication with the left relief passage 40 via the
relief 90. At this point, the pressurized primary fluid in the
right control passage 56 from the right main passage 52 acting on
the right pilot piston 66 will cause the first spool 60 to shift
to its left position while the free piston 82 continues towards
the position in which it abuts the second stop 94. When the ~-
first spool 60 of the first valve 30 reaches the left position,
pressurized primary fluid from the primary fluid inlet 16 is
supplied to the right pilot passage 34 to cause a shift in the
second valve 32 of the second spool 70 to its left position also.
As would be evident to those skilled in the art, with the
free piston 82 and the first and second valves 30 and 32 in their
left positions, the second half of a cycle similar to the above -~
described first part of the cycle begins. Secondary fluid is
' drawn through the left inlet check valve 46 from the second
reservoir 21 and pumped from the main bore 42 through the outlet
,- check valve 48 to the secondary fluid function 24.
It should be noted that the above fluid system 10 would by
nature be pressure compensated. The free piston 82 and the right
and left driving p:istons 84 and 86 would have forces acting in `~
opposition and the resulting forces would accelerate the mass of
these pistons thus increasing the output of the pump when the
pressure drops. The mass of the system would come to equilibrium
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1 at some pressure that produced a zero resultant force. As would
be evident to those skilled in the art, flow restriction losses
inside the system 10, itself, would form part of the pressure
load on the free piston 82 and there would be a limiting avail-
able acceleration force corresponding to zero pressure at the
secondary fluid outlet passage 22. Naturally, the fluid system
10 should be designed such that acce:Leration of the pistons take
a small portion of the cycle. This can be accomplishea by in-
creasing the displacement of the free piston 82, reducing the
mass of the pistons and spools, and minimizing flow restrictions.
While the invention has been described in conjunction with a
- specific embodiment, it is to be understood that many alterna-
tives, modifications and variations will be apparent to those
skilled in the art in light of the aforegoing description. For
example, one pair of check valves 46 and 50 could be connected to
one fluid circuit and the second pair of check valves 44 and 48
could be connected to another different fluid circuit with the
free piston 82 being driven by a third fluid circuit containing a
different fluid from the other two fluids. Accordingly, it is
intended to embrace all such alternatives, modifications, and
variations which fall within the spirit and scope of the appended
claims.
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