Jan. 13, 1970
M. SCHUMAN\
3,489,335
OSCILLATING FREE PISTON PUMP
Filed July 31, 1968
2 Sheets-Sheet l
4 M267
/5
L
/?
/6‘ “@
E
J K
Q
19
E
(0//é
W4
rm/ mag“
/7
*_
F162
3
/ Q14
W
29
¢
2/ FIGS
“I
INVENTOR
MARK
wax/Ei-
t/'
SCH UMAN
BY qw/gwl ?wmf/ g‘ M
ATTORNEYS
Jan. 13, 1970
M. SCHUMAN
3,489,335
OSOILLATING FREE PISTON PUMP
Filed July 31, 1968
2 Sheets-Sheet 2
47
57
FIG. IO
64
59
63
WARM
?esmvo/
6/
55
56
351.
1%‘
#85‘
70-—~-~
(58
FIG. [2
8/
"‘-Z/
73’
ii
"
I
‘L-
8?"
INVENTOR
MARK
> '
BY gw?l
SCHUMAN
f.‘ M
ATTORNEYS
f‘
United States Patent O ”ice
3,489,335
Patented Jan. 13, 1970
1
2
3,489,335
Another object is to provide a simple, quiet operating
pump construction utilizing a constantly operated heater
which continually, rather than intermittently, heats the
OSCILLATING FREE PISTON PUMP
Mark Schuman, Ann Arbor, Mich.
(101 G St. SW., A516, Washington, D.C. 20024)
Filed July 31, 1968, Ser. No. 749,130
gas, but wherein the gas intermittently applies pressure to
the piston to cause continued oscillation thereof.
Another object of this invention is to utilize, as the ther1
Int. Cl. F04b 35/00
U.S. Cl. 230-51
6 Claims
mal power means for such pump, a temperature differ‘
ential provided by means of heating and cooling reser
voirs, or by means of natural temperature di?erentials
such as the heat of sunlight as compared to ambient tem
ABSTRACT OF THE DISCLOSURE
A thermal powered pump formed of a cylinder, con
perature or available water temperature or the like.
taining a free, oscillating piston, and having a heating
chamber for providing above the piston, heated, expand
ing gases to be pumped for moving the piston downwardly
to compress the gas located beneath it which, in turn raises 15
A further object of this invention is to provide a pump
as described above but utilizing a double action operation,
which includes a pair of opposed pistons operating oppo
sitely and synchronously to thereby balance out low fre
quency piston vibrations.
piston so that the piston oscillates up and down, and with
These and other objects and advantages of this inven—
the pump outlet located above the piston for expelling the
tion will become apparent, upon reading the following
gas. A shunt interconnects the cylinder portions above
description, of which the attached drawings form a part.
and below the piston for carrying gas to the portion below
the piston for maintaining the center of oscillation of the 20
DESCRIPTION OF DRAWINGS
piston with respect to the cylinder.
FIG. 1 is a schematic, elevational, cross-sectional view
of the oscillating free piston pump herein.
FIG. 2 is an enlarged, cross-sectional schematic view
BACKGROUND OF INVENTION
of the upper, heating chamber portion of the cylinder.
25
Conventional piston type pumps used for pumping
FIG. 3 is an enlarged, fragmentary, elevational view of
the piston and a portion of the cylinder.
gases, such as air or the like, generally include a cylinder
containing a movable piston which is connected to a
FIGS. 4 through 8 show successive steps in the opera
motor or engine as a power operating means for the
tion of the pump.
FIG. 9 schematically illustrates the use of the pump in
pump. In addition, such types of pumps are generally
bulky, noisy, and relatively expensive in construction, and
powering a turbo-generator, and also illustrates a modi?ed
cannot operate on continuously applied thermal power.
Thus, this invention is concerned with providing a
heater.
simply construction, thermally powered pump mechanism,
ential is utilized to provide the thermal power.
in the form of a free ?oating piston oscillating within a
cylinder. Power is supplied by a suitable heating means,
double acting pump utilizing a pair of opposed free
such as a continuously operated electrical heating coil
pistons.
FIG. 10 illustrates a modi?cation wherein a heat diifer
FIG. 11 illustrates a further modi?cation showing a
or carbon-type fuel heater, which is relatively e?icient and
FIG. 12 illustrates another modi?cation similar to that
inexpensive. The relative size of the pump, as compared to
of FIG. 10.
prior pumps, is reduced and its noise of operation, both
DETAILED DESCRIPTION
electrical and audible, is considerably reduced. The im 40
FIG. 1 illustrates a pump 10 formed of a vertically ar
proved pump may serve a number of pumping functions,
as for example, to provide high pressure gases to a turbine
or turbo-generator, etc.
SUMMARY OF INVENTION
45 13 through which the gas to be pumped enters the cylinder.
Summarizing, the invention herein contemplates oscil
lating a free piston by means of initially placing it be
tween equal volumes of gas which act like a pair of com
pression springs to push the piston back and forth be
tween them, but with one spring having an added push
on its expansion to prevent the oscillation from dying
out. Thus, one of the gas volumes is heated and expands
to push the piston to compress the other gas volume which
rebounds like a spring to return the piston to expel, and .
thereby pump the heated gas. The repeated oscillation
steps generally comprise supplying heated expanding gas,
movement of piston to compress the opposite gas volume,
and rebound and expulsion of the heated gas. The supply
of heated gas provides the pressure to maintain the oscilla
tion and prevent it from slowing down and stopping.
Additional gas is intermittently supplied to the opposite
gas volume to maintain the center of oscillation of the
piston. The oscillation is initially started by use of an
ranged, closed cylinder 11, containing a loosely ?tted, free
piston 12 adapted to oscillate vertically up and down
within the cylinder. The cylinder includes an inlet pipe
Between the inlet pipe and the body of the cylinder is
arranged a heating chamber 14 containing a suitable heat
ing element 15 such as an electrical heating coil powered
by an outside electrical source, such as a conventional
house circuit.
The inlet to the heating chamber is closed by a valve
16 and the outlet is closed by a valve 17, these being one
Way type of valves, passing the gas only in the direction
from the inlet towards the main body of the cylinder and
closing when necessary to prevent the gas from returning
back to the inlet.
A pump outlet pipe 18 is arranged at the upper portion
of the cylinder and contains a suitable one-way outlet
valve, as for example, a conventional ball check valve
19, which leads into a surge or storage tank 20' for smooth
ing out the pulsating pumped gas.
A shunt pipe 21 is arranged around the cylinder, with
its upper end 22 connected to the inlet pipe 13 and its
auxiliary starting pump which use is discontinued once 65 lower end 23 connected to the interior of the bottom of
the cylinder through a one-way inlet valve 24, such as
the piston oscillation stabilizes.
a suitable ball check valve or the like which permits the
An object of this invention is to drive an oscillating,
free piston within a cylinder by means of heated expand
ing gas applied to one face of the piston and non-heated
compressed gas, which is compressed by the piston itself,
at the opposite face of the piston, and to expel or pump
the heated gas.
flow of gas into the bottom of the cylinder through the
shunt pipe but not in the reverse direction.
The piston 12, being loosely ?tted within the cylinder,
is gas lubricated for substantially frictionless movement.
Preferably, the piston is formed of a cylindrically shaped,
3
3,433,335
porous, sintered metal, side wall 25 which is gas pervious
(see FIG. 3). The piston is closed by a top cover 26 hav
ing a central opening 27 and closed by a suitable one
way valve 28 (shown schematically) so that it will ?ll with
gas on its up stroke while permitting the pressurized gas
to continuously leak through the wall 25. This serves to
gas lubricate the piston relative to the cylinder wall and
to maintain the piston co-axially with the cylinder.
While a variety of one-way valves may be found for the
4
inlet valve 17 to open to release heated gas into the
cylinder, which gas expands and drives the piston down.
As the piston moves further down, reducing the pres
sure within the heating chamber to below inlet 13 pres
sure, the heating chamber inlet valve 16 also opens to
admit more gas through the inlet 13 (see FIG. 7). The
downward movement of the piston not only permits the
cylinder portion above the piston to become ?lled with
the incoming gas, but also compresses the gas located With
inlet and outlet of the heating chamber, FIG. 2 illus 10 in the cylinder below the piston. Hence, at the lowermost
trates one suitable form which comprises wafers 16 and
part of the stroke downwardly, the compressed gas be
17 having an inlet stop or limit 29 and an outlet stop or
neath the piston reaches its point of maximum compres
limit 31. The outlet stop provides a greater distance of
sion where it and the piston tend to rebound as a result
movement for the wafer 17 than is provided for the wafer
of this pressure exceeding the pressure above the piston.
16 so that the wafer 17, in e?ect, is a delayed acting 15 At that point, as shown in FIG. 8, the piston again starts
valve because of its greater required movement and lower
upwardly, compressing the gas above it, and expelling a
restriction of reverse gas flow. The wafers close the inlet
portion of the gas into the heating chamber 14 through the
opening 30 and the outlet opening 32 of the heating
valve 17 which remains open slightly longer than does
chamber 14. The object here is to provide an outlet valve
the upper valve 16 to insure closing of the valve 116 and
for the heating chamber which closes at a short time in 20 to accumulate additional gas within the heating chamber
terval after the inlet valve closes for reasons to be ex
for higher efficiency. As the piston rises towards the top
plained below. Thus, other forms of valves such as sole
of the stroke, the pressure above it exceeds the surge tank
noid operated valves or other suitable timed valves may
pressure and gas is expelled out the outlet 18. The cycle
be utilized for this purpose.
is then repeated as shown beginning with FIG. 4.
Referring to FIG. 1, the pump also includes an auxil 25
In this manner, the piston rapidly oscillates upwardly
iary starter pump 35 for start-up purposes. This comprises
and downwardly, pumping out a pulsating discharge into
an inlet pipe 36 leading from the bottom of the cylinder
the surge tank 20 and relying upon the continuously ap
and opening into a bellows 37 which is connected to a
plied heat energy to provide it with the expanding gases
piston rod 38 having a piston 39 arranged within a cyl
necessary for operation.
inder 40 containing a compression spring 41. In addition,
Before the piston stabilizes and oscillates as described
the rod is surrounded by a conventional solenoid coil 42.
above, at the outset of its operation, it is necessary to
The solenoid is arranged to periodically move the piston
start at the regular oscillation by means of starter 35. In
rod 38 to the left, as referring to FIG. 1, whereas the
essence, its bellows 37 alternately pumps and draws an
spring ~41 returns the piston rod to the right to thereby
amount of gas into and from the cylinder, beneath the
pump the bellows. The bellows sucks gas out of the cyl 35 piston, at approximately the natural frequency of the
inder to lower the piston 12, and pumps gas into the cyl
oscillation of the piston. Thus, the solenoid is properly
inder to raise the piston 12. It is used for a short time to
timed to move the rod 38 with the bellows at such fre
quency. The starter is used until such time as the piston
start the normal pump operation.
oscillation stabilizes, at which time the starter is turned
OPERATION
40 off. This may amount to a few minutes of operation.
MODIFICATION
During normal operation, the piston oscillates upward
ly and downwardly, with heated gas entering the cylinder,
FIG. 9
above the piston, from the heating chamber and with this
FIG. 9 illustrates a modi?cation wherein the heating
gas being pumped out of the cylinder through the outlet
coil is in the form of a pipe 45 opening into a suitable
18 during the top portion upstroke of the piston stroke.
fossil type heater 46, such as a natural gas burner type
FIGS. 4 through 8 schematically show certain of the
heater, connected in turn to a tank 47 of fuel gas. Other
steps in the operation of the pump.
types of suitable heaters may be used, such as a petro
FIG. 4 illustrates the piston travelling upwardly near
the top of its upstroke. Here the heating chamber valves
16 and 17 are closed, gas is being expelled through the
outlet 18 whose check valve 19 is open. The arrows be
neath the piston, within the cylinder, represent the expan
leum heater, coal burner or the like. The heated gas from
the heater 46 passes through the coil 45 and then out
through the end 48 into a discharge stack.
FIG. 9 also illustrates the pump as being used to power
a conventional turbo-generator 49 which generates elec
sion or rebound of gas, located below the piston, which
tricity. The gas pumped through the generator 49 is cooled
has been previously compressed by the downward move 55 in a cooling tank 50 or by other cooling means such as
ment of the piston.
?ns surrounding the return pipe 51 which returns the gas
During this time, the heating element 15, which is con
back to the inlet 13. This illustrates a closed circuit gas
tinuously operated, heats the gas contained within the heat
movement wherein the gas is recirculated.
ing chamber 14, causing the gas pressure to increase, as
In the embodiment illustrated in FIG. 1, the gas may
shown by the arrows in FIG. 4. Next, as seen in FIG. 5, 60 be air, in which case no recirculation is contemplated, or
gas compressed by the upward movement of the piston,
it may be a gas of more value which required recirculation
slows such upward movement, stops it, and starts to drive
and hence, interconnection between the inlet and outlet
it downwardly. Simultaneously, gas exhausts through out
pipes ultimately.
let 18, until outlet check valve 19‘ closes due to the higher
The operation of the pump shown in FIG. 9 is otherwise
pressure of the gas contained within the surge tank 20. 65 the same as that described above.
In FIG. 5, the valve 16 is shown in its open position.
FIG. 10
In addition, a small amount of gas, as needed, may
enter into the bottom of the cylinder through the shunt
FIG. 10 illustrates a further modi?cation which con
pipe 21, whose check valve 24 is open so that pressure
templates utilizing a temperature differential in providing
below the piston does not drop below the inlet pressure.
the heat to the pump. As an example, above the heating
Where the gas being pumped is atmospheric air, the shunt
chamber 14 is located a cooling chamber 55 having a cool
pipe may be omitted and the check valve simply opened
ing coil 56 for ?rst cooling the inlet gases, which are then
to atmosphere, so that, in e?ect, there is still a shunt.
heated by the heating coil located within the heating cham
In FIG. 6, the exhaust check valve 19 is closed, and
ber. Once the gas is heated and enters the cylinder, the
the pressure of the gas in the heating chambery14 causes 75 operation is the same as described above, with the gas
5
3,489,335
powering a turbo-generator 49 and then being recirculated
back to the cylinder through the return pipe 51.
The coil 56 may be cooled by the use of a cold water
reservoir 57, with the heated coil 58 warmed by a warm
reservoir. The cooled reservoir may be an available water
supply, such as a natural well, pond, etc.
It is contemplated that this arrangement may utilize
ambient temperatures and sun heat to operate around
the clock. To this end, a heat exchanger coil 60 is provided
and mounted upon a panel 61 which could be arranged 10
upon a rooftop or out of doors where it is exposed to
the sun. The coil is connected through valve 62 to a cool
reservoir inlet pipe 64 and a warm reservoir inlet pipe 65
and through a valve 63 to a cool reservoir outlet pipe 66
and a warm reservoir outlet pipe 67. In this case, the 15
6
way chamber inlet and chamber outlet valves for
controlling gas ?ow only towards the cylinder and for
closing upon upward movement of the piston, with
the chamber outlet valve being formed to close
shortly after the chamber inlet valve closes;
said gas outlet having a one-way outlet valve for pass
ing the pumped gas only out of the cylinder;
whereby downward movement of the piston is e?ected
by expansion of the heated gases entering the cyl
inder from the heating chamber and by gas com
pressed above the piston applying a force to the top
of the piston, and upwards movement of the piston
is effected solely by compression and rebound of the
compressed gas below the piston applying an upwards
force upon the bottom of the piston.
reservoirs may be large water tanks. Thus, during the day,
2. A construction as de?ned in claim 1, and including a
when the sun is available to provide heat, by adjusting
starter pump connected to the cylinder below the piston,
the valves 62 and 63, the liquid in the warm reservoir may
said starter pump having means for regularly and periodi
be heated and the liquid in the cool reservoir simply left
cally pumping gas into and out of the cylinder below the
at ambient temperature, preferably in a cool, shaded 20 piston at the natural frequency of oscillation of the piston
place. In the evening, when the sun is no longer available,
for a period of time suf?cient to stabilize the normal os
the valve 62 and 63 may‘ be reversed to utilize radiant
cillation of the piston within the cylinder.
cooling and the cold ambient temperature to cool the cool
3. A construction as de?ned in claim 1, and includ
reservoir further below the liquid in the warm reservoir.
ing a heater element contained within said heater cham
In this manner, the net result is that the gas entering 25 ber and constantly operated to maintain a continuous heat
through inlet 13 is ?rst cooled by the coil 56 and is then
input into said chamber by an outside source of heat
heated by the coil 58 to provide for greater pressure build
up and subsequent expansion. Thus, the differential of
energy.
temperature, provided as described above or in other
equivalent ways, serves as a means for operating the
pump.
ing a cooling chamber, containing means for cooling
gases passed therethrough, connected between the gas
inlet and heating chamber for reducing the temperature of
and contracting the speci?c volume of the gas prior to
entry of the inlet gas into said heating chamber.
FIG. 11
4. A construction as de?ned in claim 1, and includ
5. A construction as de?ned in claim 1, and including
FIG. 11 illustrates a modi?cation in the form of a
double ended or double acting pump 70 comprising a cyl 35 a second free piston located in the cylinder spaced above
the ?rst piston and the gas inlet and outlet, with the
inder 71 containing a pair of free pistons 72 and 73. The
upper end of the cylinder also connected to the gas inlet
inlet 74 delivers the gas to the heating chamber 75 which
by a shunt pipe containing a one-way shunt valve for
contains the heating coil 76 and has an inlet valve 77 and
controlling gas flow only into the upper end of the
an outlet valve 78 located between the two pistons. Also,
the pump outlet pipe 79 is located between the two pistons 40 piston above the second piston;
whereby the two pistons move respectively oppositely
and discharges through a one-way valve 80 into the surge
and synchronously upon entry of heated gas into
tank 81.
the cylinder between them and upon rebound of the
The opposite ends of the cylinder are connected to the
compressed gas when the pistons reach near their
inlet 74 by means of a shunt pipe 82 containing one-way
respective opposite cylinder ends.
valves 83 at each end of the cylinder.
45
6. An oscillating free piston pump for pumping a gas,
For purposes of starting the pump, a pair of starters
comprising a closed cylinder containing a free piston
35 are provided at each end of the cylinder, although
loosely ?tted therein for oscillation along the axis of the
one starter might be used with pipes leading to each of
cylinder;
the opposite ends.
said piston dividing the cylinder into a pumping cham
The operation of this pump is the same as described 50
ber closed by an end of the piston and compression
before except here, the two pistons move oppositely and
chamber closed by the opposite end of the piston;
synchronously.
a gas inlet and a gas outlet located in said pumping
FIG. 12
chamber with a continuously operating heater lo
cated between said inlet and outlet, and including
FIG. 12 illustrates a modi?cation similar to that of 55
a one-way inlet valve at said inlet and a one-way
FIG. 10, with the exception that no separate heating cham
exit valve at said outlet;
ber is provided below cooling chamber 55 which con
means for initially starting the piston to oscillate within
tains the cooling coil 56 and is closed at its bottom by a
said chamber at a predetermined frequency;
one-way valve 85. Here the heating coil is exposed above
and means for connecting the compression chamber to
the piston. While heating the gas in the up-stroke is rela 60
tively ine?'icient, this construction is simpler and may have
inlet gas pressure at about the time that the piston
certain low efficiency applications.
reaches the end of its stroke towards the inlet;
Having fully described an operative embodiment of this
wherein movement by the piston away from the inlet
invention, I now claim:
compresses gas contained in the compression chamber
1. An oscillating free piston pump, for pumping gas, 65
until maximum compression is reached and the com
comprising a closed vertical cylinder containing a free
pressed gas rebounds and acts as the sole means for
piston loosely ?tted therein for vertical oscillation;
driving the piston towards the inlet for expelling gas
a gas inlet and a gas outlet located above the piston, the
out through the outlet and simultaneoutly compress
inlet being also connected by a shunt pipe through
ing gas in the pumping chamber, and movement away
a shunt one-way valve to the opposite end of the 70
from the inlet is e?ected by a combination of ex
cylinder for permitting gas to ?ow into the cylinder
panding heated gas entering the pumping chamber
below the piston;
and compressed gas resulting from piston movement
a heating chamber connected between said inlet and
towards the inlet.
the cylinder above the piston for heating incoming
gas before entry into the cylinder and having a one 75
(References on following page)
3,489,335
7
‘1 References Cited
-
3,170,406»
UNITED STATES PATENTS
2,910,119
2,040,433
3,087,438
10/1959 wennelbergi
5/ 193 6 Du?aud.
4/1963 Ciesielski.
3,285,001
,
8'
2/1965
Robertson.
11/ 1966 Turnblade.
WILLIAM L. FREEH, Pnmary Exammer
5
US. Cl. X.R.
230—5‘6