U.S. patent application number 09/878293 was filed with the patent office on 2002-12-12 for pressurizer for a rocket engine.
Invention is credited to Knight, Andrew F..
Application Number | 20020184875 09/878293 |
Document ID | / |
Family ID | 25371738 |
Filed Date | 2002-12-12 |
United States Patent
Application |
20020184875 |
Kind Code |
A1 |
Knight, Andrew F. |
December 12, 2002 |
PRESSURIZER FOR A ROCKET ENGINE
Abstract
The present invention provides for a pressurizer for
pressurizing a fluid, comprising a pressurant entrance for the
introduction of a pressurant, a fluid entrance for the fluid, a
fluid exit for the fluid, and a transfer chamber movable in a cycle
with respect to the fluid exit, where for a portion of a cycle the
pressurant exerts a force on the fluid inside the transfer chamber.
In a preferred aspect of the present invention, the pressurizer
further comprises a spindle housing more than one transfer chamber,
rotatable about an axis between the fluid entrance and the fluid
exit. In another preferred aspect, the transfer chamber comprises
either a flexible membrane or a movable piston to separate the
pressurant and the fluid.
Inventors: |
Knight, Andrew F.;
(Washington, DC) |
Correspondence
Address: |
Andrew F. Knight
1111 Arlington Blvd. #317
Arlington
VA
22209
US
|
Family ID: |
25371738 |
Appl. No.: |
09/878293 |
Filed: |
June 12, 2001 |
Current U.S.
Class: |
60/259 |
Current CPC
Class: |
F02K 9/56 20130101; F02K
9/50 20130101 |
Class at
Publication: |
60/259 |
International
Class: |
F02K 009/50 |
Claims
I claim:
1. A pressurizer for pressurizing a fluid, comprising: a pressurant
entrance for the introduction of a pressurant; a fluid entrance for
said fluid; a fluid exit for said fluid; and a transfer chamber
movable in a cycle with respect to said fluid exit, wherein for a
portion of a cycle said pressurant exerts a force on said fluid
inside said transfer chamber.
2. The pressurizer as claimed in claim 1, further comprising a
spindle housing more than one transfer chamber.
3. The pressurizer as claimed in claim 2, wherein the spindle is
rotatable.
4. The pressurizer as claimed in claim 3, wherein the spindle is
rotatable about an axis between said fluid entrance and said fluid
exit.
5. The pressurizer as claimed in claim 1, wherein the transfer
chamber comprises a flexible membrane to separate said pressurant
and said fluid.
6. The pressurizer as claimed in claim 1, wherein the transfer
chamber comprises a movable piston to separate said pressurant and
said fluid.
7. The pressurizer as claimed in claim 1, further comprising a
pressurant exit for a pressurant exhaust.
8. The pressurizer as claimed in claim 7, wherein said pressurant
exhaust is exhausted in a direction substantially opposite a
direction of motion of said transfer chamber.
9. The pressurizer as claimed in claim 1, further comprising a
motor to move said transfer chamber.
10. The pressurizer as claimed in claim 1, wherein a cross section
of said pressurant entrance is larger than a cross section of said
fluid exit.
11. The pressurizer as claimed in claim 7, wherein a cross section
of said pressurant exit is larger than a cross section of said
fluid entrance.
12. A rocket engine system, comprising: a pressurant; a pressurant
container; a propellant; a propellant container; a rocket engine;
and a transfer chamber movable in a cycle with respect to said
rocket engine, wherein for a portion of a cycle said pressurant
exerts a force on said propellant inside said transfer chamber.
13. The rocket engine system as claimed in claim 12, wherein for a
portion of a cycle a bouyant force causes said propellant to flow
into, and said pressurant to flow out of, said transfer
chamber.
14. The rocket engine system as claimed in claim 12, further
comprising a heating means for heating said pressurant.
15. The rocket engine system as claimed in claim 14, wherein said
heating means comprises a heat conductor for conducting heat from
said rocket engine to said pressurant.
16. The rocket engine system as claimed in claim 12, wherein a
pressurant exhaust exerts a force on said propellant inside said
propellant container.
17. The rocket engine system as claimed in claim 12, wherein said
propellant comprises an oxidizer and a fuel.
18. The pressurizer as claimed in claim 1, wherein a cross section
of said fluid entrance is greater than a cross section of said
fluid exit.
19. The rocket engine system as claimed in claim 12, further
comprising an engine conduit between said transfer chamber and said
engine and a propellant conduit between said transfer chamber and
said propellant container, wherein a cross section of said
propellant conduit is greater than a cross section of said engine
conduit.
Description
BACKGROUND
[0001] Rocket engines require propellants to be fed to them at very
high pressures. This has historically been accomplished in two
general ways: first, with the use of a pressurized fluid, such as
high pressure helium; and second, with the use of a pump. In the
first way, a pressurized fluid is added directly to the propellant
tank and exerts a force on the propellant. Nitrogen and helium,
both inert gases, pressurized to a pressure as high as 50,000 PSI,
have been used successfully in the past. As they are inert, there
need be no barrier (e.g. membrane or piston) placed between these
pressurized fluids and the propellant. The problem with this
method, however, is that the pressurized fluid also exerts a force
on the propellant tank. Because of the extremely high pressures
required of the pressurized fluid, the walls of the propellant tank
must be thick enough to withstand the pressure. The propellant tank
is therefore very heavy. Rockets employing the pressurized fluid
must use a greater proportion of their thrust lifting this extra
weight, and therefore they are not as efficient as rockets that do
not require this added weight.
[0002] Historically, one way to solve the above weight problem is
to employ the use of a pump. Pumps (e.g. reciprocating or
centrifugal pumps) are generally very complex and require their own
driving means, such as an engine. Further, the engine driving the
pump burns a significant percentage of the total propellant. For
small rocket engine systems, since a pump is too complicated and
too heavy, pressurized fluids are generally used to pressurize the
propellant. However, for large rocket engine systems, pumps have
the advantage that the walls of the propellant tank need not be
thick, since there is little or no pressure in the tank. Therefore,
the propellant tank is much lighter, and the added weight of the
pump is more than offset by the reduction in propellant tank
weight.
[0003] U.S. Pat. No. 3,213,804 to Sobey discloses fluid pressure
accumulators that are connected to sources of low and high pressure
by means of butterfly valves. Essentially, the pressurized fluid
exerts force on the propellant in small, designated containers.
While the walls of these containers must be thick in order to
withstand the high pressure of the pressurized fluid, the walls of
the propellant tank need not be. Therefore, the total weight of the
rocket engine system employing Sobey's invention may be less than
that of the previously discussed rocket engine system because these
containers (fluid pressure accumulators) are small in comparison to
the propellant tank.
[0004] A problem with Sobey's invention, however, is its
complicated use of valves. In order to reduce the weight of Sobey's
invention further, the sizes of the fluid pressure accumulators
must decrease (thus reducing their weight). However, as they
decrease, the rotation speed and precision of the butterfly valves
must increase in order to accommodate the same propellant flow rate
to the rocket engine. This places great stresses on the valves, and
eventually a point is reached at which the valves cannot reliably
rotate fast enough to provide the required timing.
SUMMARY OF THE INVENTION
[0005] The present invention provides for a pressurizer for
pressurizing a fluid, comprising a pressurant entrance for the
introduction of a pressurant, a fluid entrance for the fluid, a
fluid exit for the fluid, and a transfer chamber movable in a cycle
with respect to the fluid exit, where for a portion of a cycle the
pressurant exerts a force on the fluid inside the transfer chamber.
In a preferred aspect of the present invention, the pressurizer
further comprises a spindle housing more than one transfer chamber,
rotatable about an axis between the fluid entrance and the fluid
exit. In another preferred aspect, the transfer chamber comprises
either a flexible membrane or a movable piston to separate the
pressurant and the fluid. In another preferred aspect, the
pressurizer further comprises a pressurant exit for a pressurant
exhaust. In another preferred aspect, the pressurant exhaust is
exhausted in a direction substantially opposite a direction of
motion of the transfer chamber. In another preferred aspect, the
pressurizer further comprises a motor to move said transfer
chamber. In another preferred aspect, a cross section of the
pressurant entrance is larger than a cross section of the fluid
exit, and a cross section of the pressurant exit is larger than a
cross section of the fluid entrance. In another preferred aspect, a
cross section of the fluid entrance is greater than a cross section
of the fluid exit.
[0006] The present invention also provides for a rocket engine
system, comprising a pressurant, a pressurant container, a
propellant, a propellant container, a rocket engine, and a transfer
chamber movable in a cycle with respect to the rocket engine, where
for a portion of a cycle the pressurant exerts a force on the
propellant inside the transfer chamber. In a preferred aspect, for
a portion of a cycle a bouyant force causes the propellant to flow
into, and the pressurant to flow out of, the transfer chamber. In
another preferred aspect, the rocket engine system further
comprises a heating means for heating the pressurant, where the
heating means comprises a heat conductor for conducting heat from
the rocket engine to the pressurant. In another preferred aspect, a
pressurant exhaust exerts a force on the propellant inside the
propellant container. In another preferred aspect, the propellant
comprises an oxidizer and a fuel. In another preferred aspect, the
rocket engine system further comprises an engine conduit between
the transfer chamber and the engine and a propellant conduit
between the transfer chamber and the propellant container, where a
cross section of the propellant conduit is greater than a cross
section of the engine conduit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 shows a schematic view of a rocket engine system
employing the pressurizer described herein.
[0008] FIG. 2 shows a perspective view of a preferred embodiment of
the pressurizer described herein.
[0009] FIG. 3 shows a perspective view of the pressurizer in FIG. 2
without the spindle.
[0010] FIG. 4 shows a perspective view of the spindle.
[0011] FIG. 5 shows a cut-away view of FIG. 4.
[0012] FIG. 6a shows a top view of the top chamber separator.
[0013] FIG. 6b shows a bottom view of the bottom chamber
separator.
[0014] FIG. 7 shows a perspective view of the pressurizer in FIG. 2
with a motor.
[0015] FIG. 8 shows a perspective view of another preferred
embodiment of the pressurizer described herein.
[0016] FIG. 9 shows a perspective view of a spindle associated with
the pressurizer in FIG. 8.
[0017] FIG. 10 shows a schematic view of a rocket engine system
with a heater for the pressurant.
[0018] FIG. 11 shows a schematic view of a rocket engine system
with the propellant tank pressurized by the pressurant exhaust.
[0019] FIG. 12 shows a schematic view of a rocket engine system
employing another embodiment of the pressurizer described
herein.
[0020] FIG. 13 shows a perspective view of the pressurizer shown in
FIG. 12.
[0021] FIG. 14 shows a perspective view of the pressurizer in FIG.
13 without the spindle.
[0022] FIG. 15 is a cut-away view of a spindle with a movable
piston in each transfer chamber.
[0023] FIG. 16 is a perspective view of a spindle with very thin
transfer chambers.
[0024] FIG. 17 is a perspective view of a spindle with a flexible
membrane in each transfer chamber.
[0025] FIG. 18 is a cut-away view along cross section A-A shown in
FIG. 17.
[0026] FIG. 19 is a schematic view of a rocket engine system
employing two propellants.
DETAILED DESCRIPTION
[0027] In the following description, the use of "a," "an," or "the"
can refer to the plural. All examples given are for clarification
only, and are not intended to limit the scope of the invention.
[0028] Referring to FIG. 1, according to a preferred embodiment, a
rocket engine system includes a propellant tank 10 connected by a
propellant conduit 6 to a pressurizer 16, a pressurant tank 18
connected by a pressurant conduit 36 to the pressurizer 16, and a
rocket engine 2 with a nozzle 4 connected by an engine conduit 32
to the pressurizer 16. The propellant tank 10 contains a propellant
12 with meniscus 14. Flow of the propellant 12 into pressurizer 16
is controlled by propellant valve 8. A pressurant tank 18 contains
a pressurant 20. Flow of the pressurant 20 into pressurizer 16 is
controlled by pressurant valve 22. Flow of propellant 12 from
pressurizer 16 to engine 2 is controlled by engine valve 26.
Pressurant exhaust is released from exhaust conduit 34, and its
flow is controlled by exhaust valve 24.
[0029] Propellant 12 combusts in engine 2 and the resulting gas
accelerates through nozzle 4. Propellant 12 can be any
monopropellant, such as a substance that decomposes by itself or in
the presence of a catalyst. One example is hydrogen peroxide.
Propellant 12 can also be a fuel or an oxidizer in a hybrid rocket
engine system. For example, propellant 12 could be liquid oxygen
and engine 2 could contain a solid resin fuel. Further, propellant
12 need not be a reacting substance at all--it could be a working
medium that is heated by an external heat source. For example,
propellant 12 could be liquid hydrogen and engine 2 could contain a
nuclear reactor that heats the hydrogen to high pressures.
[0030] Pressurant 20 can be any high-pressure fluid, and the
following description is meant as an example and not as a
limitation. Pressurant 20, if it comes into direct contact with the
propellant 12, should be nonreactive with propellant 12. (An
embodiment will be described later in which the pressurant 20 does
not come into contact with propellant 12.) Further, it should not
react with the walls of the pressurant tank 18 or any of the
components of the pressurizer herein described. For example, two
fluids that meet this description are inert gases such as helium
and nitrogen. However, both of these fluids are gases at room
temperature (regardless of their pressure); therefore, a high
density may be difficult to obtain. A high density for pressurant
20 is necessary so that a large quantity of pressurant 20 can be
held in a small pressurant tank 18. Because pressurant tank 18 is
designed to withstand very high pressures, its walls may be very
thick, resulting in a large weight. Therefore, the smaller the
pressurant tank 18, the better. In a preferred embodiment of the
present invention, the pressurant 20 is a liquid with a very high
vapor pressure. For example, liquid carbon dioxide at room
temperature has a vapor pressure of approximately 750 PSI. However,
750 PSI, while high, may not be high enough. As another example,
liquid nitrogen can be heated until its vapor pressure is, for
example, 2000 PSI. Because of the very high vapor pressure
attainable, and because liquid nitrogen is much denser than gaseous
nitrogen, liquid nitrogen may be a good choice for pressurant 20.
One skilled in the art will realize that a plethora of other good
choices exist for pressurant 20.
[0031] Referring to FIG. 19, in another preferred embodiment of the
present invention, the rocket engine system comprises two
propellants, a fuel 78 contained in a fuel tank 76 and an oxidizer
80 contained in an oxidizer tank 82. Each of the fuel and the
oxidizer has its own pressurizer 16, and the pressurizers 16 may or
may not share a common pressurant 20. In other embodiments, the
rocket engine system could comprise more than two propellants, or
two propellants other than a fuel and oxidizer. For example, it
could comprise a fuel, an oxidizer, and a catalyst, or a
decomposing propellant and a catalyst. Many different potential
combinations of propellant tanks and pressurizers would be apparent
to one skilled in the art.
[0032] Referring now to FIG. 2, a pressurizer according to a
preferred embodiment includes: (a) a top chamber separator 28 to
which pressurant conduit 36 and exhaust conduit 34 are connected,
(b) a bottom chamber separator 30 to which engine conduit 32 and
propellant conduit 6 are connected; and (c) a rotatable spindle 26.
Propellant 12 flows into the spindle 26 through propellant conduit
6 and out of the spindle 26 through engine conduit 34. Pressurant
20 flows into the spindle 26 through pressurant conduit 36 and out
of the spindle through exhaust conduit 34. Propellant 12 and
pressurant 20 flow in the direction indicated by the arrow shown in
each conduit. The spindle 26 in this embodiment rotates in the
direction indicated by the arrow shown on the spindle 26, although
it would be obvious that it could spin in the opposite
direction.
[0033] Referring to FIG. 3, which shows the pressurizer without the
spindle 26, the pressurizer includes a rotatable connector 38 that
rotatably connects the bottom chamber separator 30 to the spindle
26. There could also be such a connector connecting the top chamber
separator 28 to the spindle 26. The connector could comprise
bearings, such as ball bearings or gas bearings. Further, there are
seals (not shown) between the moving spindle 26 and selected parts
of the top chamber separator 28 and the bottom chamber separator
30. The seals should allow the spindle 26 to spin with minimal
friction while preventing propellant 12 and pressurant 20 from
flowing into the wrong conduits at the wrong times. By way of
example and not of limitation, there could be a circular seal
around the circular hole 54 on the left side of the bottom chamber
separator 30 in FIG. 3, where the engine conduit 32 connects to the
bottom chamber separator 30. There could also be a seal on the top
of the bottom chamber separator 30 and around its circumference,
with an additional seal to separate the left and right halves of
the bottom chamber separator. The placement and material
composition of such seals would be obvious to one skilled in the
art.
[0034] Referring to FIG. 4, spindle 26 includes a plurality of
transfer chambers 42 and a center 40. Each complete rotation of the
spindle 26 is a complete cycle for each transfer chamber 42. For
each transfer chamber 42, for a portion of each cycle, propellant
12 flows inward from propellant conduit 6 (in the direction of the
arrow indicated as shown in FIGS. 2 and 3) and pressurant 20 flows
outward to exhaust conduit 34; for another portion of the cycle,
propellant 12 flows outward to engine conduit 32 and pressurant 20
flows inward from pressurant conduit 36. Now referring to FIG. 5,
each transfer chamber 42 is an individual chamber divided from the
next, so that the meniscus of propellant 12 in each transfer
chamber 42 is potentially different. First meniscus 44 is the
meniscus in a transfer chamber that is just beginning the portion
of the cycle in which propellant 12 flows outward to engine conduit
32 and pressurant 20 flows inward from pressurant conduit 36.
Fourth meniscus 50 is the meniscus in a transfer chamber that is
just ending the portion of the cycle in which propellant 12 flows
outward to engine conduit 32 and pressurant 20 flows inward from
pressurant conduit 36. In this figure, propellant 12 is flowing
downward under the force of pressurant 20.
[0035] Referring now to FIGS. 6a and 6b, the oblong holes 52 in top
chamber separator 28 of the pressurant conduit 36 and the exhaust
conduit 34 are larger than the corresponding circular holes 54 in
bottom chamber separator 30 of the engine conduit 32 and the
propellant conduit 6. Further, oblong holes 52 "cover" as well as
"precede" the circular holes 54 in the direction of rotation of the
spindle 26, as shown in the figures. The oblong holes 52 must
"cover" the circular holes 54 so that the pressurant 20 is acting
on the propellant 12 in a given transfer chamber 42 at all times
that the propellant 12 in the transfer chamber 42 is in pressure
communication with the engine 2 via engine conduit 32. Further, the
oblong holes 52 must "precede" the circular holes 54 so that the
pressurant 20 has sufficient time to pressurize the transfer
chamber and provide the proper force on the propellant 12 before
the propellant 12 is placed in pressure communication with the
engine 2 via engine conduit 32. There are other ways to achieve the
same result and would be obvious to one skilled in the art. For
example, oblong holes 52 could be thinner than shown in the figures
and still achieve the same result. Further, they need not be
oblong, nor need the circular holes 54 be circular.
[0036] As the spindle 26 (not shown in FIGS. 6a and 6b) rotates
once in the counterclockwise direction relative to a top side view
of the top chamber separator 28, each transfer chamber 42 (not
shown) completes a cycle. For illustrative purposes, suppose a
transfer chamber is currently full with propellant 12. As it moves
inside spindle 26, it first comes upon an oblong hole 52 of the
pressurant conduit 36. Pressurant 20 then rapidly flows into the
transfer chamber 42, due to its high pressure, and soon reaches an
equilibrium pressure. Next, the transfer chamber 42 comes upon
circular hole 54 of the engine conduit 32. Propellant 12 is now in
pressure communication with the engine 2, and propellant flows to
the engine 2 via engine conduit 32 under the force of pressurant 20
until most or all of propellant 12 has flowed from the transfer
chamber 42. Next, the transfer chamber 42 moves past the circular
hole 54, thus ending the pressure communication of propellant 12
with engine 2. Next, the transfer chamber moves past the oblong
hole 52 and pressurant 20 is no longer able to flow into transfer
chamber 42. The transfer chamber 42 may move past both the circular
hole 54 and the oblong hole 52 roughly simultaneously.
[0037] Next, the transfer chamber 42 comes upon an oblong hole 52
of the exhaust conduit 34. The pressurant 20 flows out of the
transfer chamber into the exhaust conduit 34 until a near
equilibrium pressure is reached between the inside of the transfer
chamber 42 and the exhaust pressure of the exhaust conduit 34. The
exhaust pressure may be atmospheric pressure, or it may be a vacuum
if the pressurizer herein described is used in space. Next, the
transfer chamber 42 comes upon a circular hole 54 of the propellant
conduit 6. The propellant 12, the pressure of which at its entrance
into the transfer chamber 42 is higher than the exhaust pressure of
the exhaust conduit 34, flows into the transfer chamber 42 as it
displaces the remaining pressurant 20, until the propellant 12
completely or mostly fills the transfer chamber 42. Next, the
transfer chamber 42 moves past the circular hole 54, thus ending
the flow of propellant 12 into transfer chamber 42. Next, the
transfer chamber moves past the oblong hole 52 and pressurant 20 is
no longer in pressure communication with exhaust conduit 34. The
transfer chamber 42 may move past both the circular hole 54 and the
oblong hole 52 roughly simultaneously.
[0038] One full cycle has been described. After this, the cycle
begins again. Because of the plurality of transfer chambers 42 in
the spindle 26, the pressurizer 16 is designed so that at any given
time at least one transfer chamber 42 is in pressure communication
with both the engine 2 via engine conduit 32 and the pressurant 20
via pressurant conduit 36 simultaneously, thus ensuring continuous,
uninterrupted flow of propellant 12 to the engine 2.
[0039] The propellant 12 at its entrance into the transfer chamber
42 is at a higher pressure than the exhaust pressure of the exhaust
conduit 34 because of a pressure head due to the height of meniscus
14 relative to the entrance of the propellant 12 into the transfer
chamber 42. However, this pressure may or may not be sufficient. In
order to increase this pressure, and thereby increase the flow rate
of propellant 12 into transfer chamber 42, the propellant tank 10
may be pressurized The propellant tank 10 need not be pressurized
to a very high pressure, and should be lower than the pressure of
the pressurant 20. (If the propellant 12 were pressurized to a
pressure at or above the pressure of the pressurant 20, there would
be no need for the pressurizer 16, and the walls of the propellant
tank 10 would have to be very thick and heavy.) By way of example
and not of limitation, the propellant tank 10 could be pressurized
to between 10 and 200 PSI, or even more, if the pressurant pressure
is exceedingly high.
[0040] Generally, the difference between the pressure of the
pressurant 20 and the working (combusting) pressure of the engine 2
is significantly greater than the difference between the pressure
of the propellant 12 at its entrance into the transfer chamber 42
and the exhaust pressure of the exhaust conduit 34. The flow rate
of a fluid (e.g. propellant 12) through a conduit (e.g. propellant
conduit 6) generally depends on several factors, including the
difference in pressure at each end of the conduit, as well as the
minimum cross sectional area of the conduit. Therefore, the flow
rate per cross sectional area is generally proportional to the
difference in pressure at each end of the conduit. A flow rate
between the propellant tank 10 and the transfer chamber 42 should
be equal to a flow rate between the transfer chamber 42 and the
engine 2. Otherwise, at the end of each cycle, each transfer
chamber 42 would have significantly more or less propellant 12 than
it did at the end of the previous cycle. If this trend continued,
it would eventually result in one of two undesirable consequences:
either propellant 12 would be lost directly through the exhaust
conduit 34, or else pressurant 20 would be fed directly into the
engine conduit 32. In order to set the flow rate between the
propellant tank 10 and the transfer chamber 42 equal to the flow
rate between the transfer chamber 42 and the engine 2, the minimum
cross sectional area of the path between the propellant tank 10 and
the transfer chamber 42 (e.g. propellant conduit 6) should be
greater than the minimum cross sectional area of the path between
the transfer chamber 42 and the engine 2 (e.g. engine conduit 32).
This is necessary to counteract the effect resulting from a
difference in pressure between the pressurant 20 and the engine 2
that is higher than the difference in pressure between the
propellant 12 at its entrance into the transfer chamber 42 and the
exhaust pressure of the exhaust conduit 34.
[0041] Therefore, one of the circular holes 54 (FIG. 6b) could be
larger than the other, the larger one corresponding to the point of
connection between the engine conduit 32 and the bottom chamber
separator 30. Further, the engine conduit 32 could have a smaller
cross section than the propellant conduit 6. It would be obvious to
one skilled in the art how to adjust the dimensions of the various
elements of the pressurizer described herein in order to assure
proper flow rates of propellant 12 into and out of transfer chamber
42.
[0042] Referring now to FIG. 7, the spindle 26, housing a plurality
of transfer chambers 42, can be rotated by an external means of
rotation, such as a motor 58 connected to the spindle 26 via motor
shaft 56. As the motor 58 spins, the spindle 26 rotates. In each
rotation of the spindle 26, each transfer chamber 42 inside is
subject to a full cycle as previously described. The motor 58 could
be an electric motor, powered by a battery or some other electric
power supply. The motor 58 could also be a piston engine or a
turbine, powered, for example, by the combustion/decomposition of
propellant 12 or the expansion of the pressurant 20. However, the
motor 58 does not need to be large or to consume much energy. It
needs only to overcome the friction resulting from the contact
between the moving spindle 26 and the stationary chamber separators
28, 30 via the seal. The greater the friction and the faster the
spinning of the spindle 26, the more work the motor 58 needs to
do.
[0043] Referring now to FIG. 8, in another preferred embodiment of
the present invention, pressurizer 16 has a spindle housing 62 with
a housing jet hole 60. In this embodiment, the spindle 26 as shown
in FIG. 9 is placed inside the spindle housing 62. The housing jet
hole 60 is a hole that penetrates the wall of the spindle housing
60 in a direction that is not perpendicular to the wall. Rather,
the housing jet hole 60 is pointed in a direction shown by arrow
"a" that is opposite the direction of rotation "b" of the spindle
26. Of course, these directions could be reversed. Further, spindle
26 contains spindle jet holes 64 corresponding to transfer chambers
42 (i.e. one spindle jet hole 64 per transfer chamber 42) that are
cut similarly to housing jet hole 60 in that they are not
perpendicular to the wall of spindle 26. Rather, they point in a
direction shown by the arrow "a." There is further a seal (not
shown) between the outer wall of the spindle 26 and the inner wall
of the spindle housing 62 so that fluid inside a transfer chamber
42 can only escape via its corresponding spindle jet hole 64 when
its spindle jet hole 64 is aligned with the housing jet hole
60.
[0044] Housing jet hole 60 should be located in the wall of the
spindle housing 62 "after" the pressurant conduit 36/engine conduit
32 pair in the direction of rotation of the spindle 26. The
function of the holes will now be explained. After a transfer
chamber 42 has just completed the part of the cycle in which it is
in pressure communication with the pressurant conduit 36, the
transfer chamber now contains some, if any, propellant 12, and is
mostly or completely full will pressurant 20. The housing jet hole
60 is located after this part of the cycle. As the transfer chamber
42 continues in its cycle, its then comes to the housing jet hole
60, so that its corresponding spindle jet hole 64 and housing jet
hole 60 line up (or approximately line up). At this point, the
high-pressure pressurant flows out of the jet holes 60, 64 in the
direction shown by the arrow "a." This flow of gas results in an
impulse reaction acting on the spindle 26, thus pushing it in the
direction shown by the arrow "b." The size and diameter of the jet
holes 60, 64 has been exaggerated in the drawings, but it would be
obvious to one skilled in the art how to adjust the size, shape,
dimensions, direction, and location of the holes in order to effect
the spinning of spindle 26 by the exhausting of jets of pressurant
20 through the holes. In this embodiment, an external driving
means, such as a motor 58, is replaced or supplemented by the
impulse reaction provided by the expulsion of pressurant 20 through
the jet holes 60, 64.
[0045] Referring now to FIG. 10, in another preferred embodiment,
pressurant tank 18 contains a heating element 66 to heat the
pressurant 20. If pressurant 20 is a liquid with a high vapor
pressure, then as the vapor expands (corresponding with the
pressurizing of the transfer chambers 42 according to the cycle
previously explained), the liquid evaporates to replenish the
vapor, causing the temperature of the liquid to drop, resulting in
a corresponding drop in the vapor pressure. In order to assure a
constant vapor pressure of the pressurant 20, heating element 66
applies heat to pressurant 20, keeping it at a constant
temperature. The heating element 66 can be an electric resistance
element or combustor in which a small quantity of propellant 12
combusts/decomposes. Further, a heat conductive lead 68 could
connect the heating element 66 with the engine 2 or the nozzle 4,
thus conducting some of the heat of combustion in the rocket engine
2 to the pressurant 20. Further, heat conductive lead 68 could
consist of conduit, thus directing a small stream of combustion
gases directly from the engine 2 to the heating element 66, and
then back to the engine 2. One skilled in the art would realize the
many ways possible to provide heat to pressurant 20 to keep it at a
constant temperature and vapor pressure.
[0046] Referring now to FIG. 11, in another preferred embodiment,
exhaust conduit 34 consists of two parts, only one of which is
shown in FIG. 11. The first part, shown in FIG. 11, is connected
directly to propellant tank 10 in order to provide pressure to
propellant tank 10. Propellant tank 10 should be pressurized by
gas, as discussed previously, if the pressure head provided by the
weight of the propellant (by way of the height of meniscus 14
relative to the pressurizer 16) is insufficient to cause sufficient
propellant flow. Propellant tank 10 can be pressurized by the
unused pressurant 20 remaining in the transfer chambers 42 just
before it is exhausted. So the first part of exhaust conduit 34
directs the flow of the unused pressurant 20 to propellant tank 10,
thus pressurizing the propellant 12. The second part of the exhaust
conduit 34 (not shown in FIG. 11) is similar to the exhaust conduit
34 shown in FIG. 10, in that it is not connected to the propellant
tank 10 In the cycle of a transfer chamber 42, the transfer chamber
42 first comes upon the first part of the exhaust conduit 34, thus
pressurizing the propellant tank 10. Next, the transfer chamber 42
moves past and ends pressure communication with the first part of
the exhaust conduit 34, and comes upon the second part of the
exhaust conduit 34, where propellant 12 can displace the remaining
pressurant 20 in the transfer chamber 42 as the remaining
pressurant 20 is exhausted via the second part of exhaust conduit
34. As would be obvious to one skilled in the art, there are many
ways to modify the rocket engine system described herein to make
use of the unused pressurant 20 to pressurize the propellant tank
10. Further, FIG. 11 shows an exhaust valve 24 that regulates the
pressure in propellant tank 10. Because the pressure of pressurant
20 is so high in relation to the needed pressure in propellant tank
10, it may be necessary to evenly vent propellant tank 10 via
exhaust valve 24 in order to keep the pressure in propellant tank
10 constant.
[0047] Referring now to FIG. 12, in another preferred embodiment of
the present invention, the pressurizer 16 is built into the
propellant tank bottom portion 70 of the propellant tank 10 as
shown. FIG. 13 shows a close-up of the pressurizer portion of the
rocket engine system shown in FIG. 12. A top chamber separator 28',
which is approximately half the size of the top chamber separator
28 shown in FIG. 2 and is connected on one side to pressurant
conduit 36, is connected on the other side to the propellant tank
bottom portion 70. A bottom chamber separator 30', which is
approximately half the size of the bottom chamber separator 30
shown in FIG. 2 and is connected on one side to engine conduit 32,
is connected on the other side to the propellant tank bottom
portion 70 (as shown in FIG. 13). The propellant conduit 6 and
exhaust conduit 34 have been replaced in this embodiment by the
propellant tank bottom portion 70. Besides these modifications,
other aspects of this embodiment (e.g. the use of a seal, the use
of a spindle 26, etc.) are similar to that described previously.
Referring now to FIG. 14, a rotatable connector 38' is located on
the bottom chamber separator 30', and a similar connector could be
located on the top chamber separator 28'.
[0048] Now a portion of the cycle of a spindle 26 will be
described. The portion of the cycle involving pressurant conduit 36
and engine conduit 32 is similar to that described previously with
regard to FIGS. 6a and 6b, and will not be repeated. After a
transfer chamber 42 has moved past conduits 32, 36, it then comes
upon the entrance to propellant tank bottom portion 70. At this
point, both the top and bottom of the transfer chamber 42 are open
to--and in pressure communication with--the propellant tank 10 and
the propellant 12 that it contains. The high-pressure unused
pressurant 20 remaining in the transfer chamber 42 then expands
against the propellant 12 located in the propellant tank bottom
portion 70, resulting in a bubble that rises due to a bouyant force
of the propellant 12 acting on the pressurant 20. As the bubble of
pressurant 20 rises, it is displaced in the transfer chamber 42 by
propellant 12, until the transfer chamber 42 is completely filled
with propellant 12 and no pressurant 20 remains. The bubble of
pressurant 20 continues rising until it breaks meniscus 14.
Pressurant 20, because of its high pressure, serves to pressurize
propellant tank 10, and exhaust valve 24 is used to regulate the
pressure inside propellant tank 10, as previously discussed. As the
transfer chamber continues in its cycle, it then comes upon the
exit of propellant tank bottom portion 70, where its pressure
communication with propellant tank 10 ends. Then, the cycle ends,
and a new cycle begins, the beginning of which has been described
before in regard to FIGS. 6a and 6b.
[0049] In another embodiment, not shown, the spindle 26 is rotated
by an external rotation means, such as a motor, engine, or turbine,
as discussed. Further, in another embodiment, the embodiment shown
in FIGS. 13 and 14 is modified with jet holes 60, 64 shown in FIGS.
8 and 9 in order to rotate spindle 26 by means of impulse reaction.
Further, in order to address the issue of flow rate discussed
previously, the cross section of the engine conduit 32 may be
smaller than shown in the drawings, and/or the chamber separators
28', 30' may be smaller so that each transfer chamber spends a
greater portion of its cycle inside propellant tank bottom portion
70. Similar modifications to achieve similar ends would be obvious
to one skilled in the art.
[0050] Referring now to FIG. 15, each transfer chamber 42 contains
a movable means for separating the pressurant 20 from the
propellant 12, such as a piston 72. Piston 72 can move up and down
inside the transfer chamber 42 while maintaining a seal with the
inside walls of the transfer chamber 42, to prevent the leak of
propellant 12 into the region above the piston 72 or the leak of
pressurant 20 into the region below the piston 72. The cycle
proceeds as previously described with regard to FIGS. 6a and 6b,
the only difference being that the pressurant 20 acts indirectly on
propellant 12 via piston 72. Piston 72 could have the added feature
that it cannot move any higher than the top of the transfer chamber
42 or any lower the than the bottom of the transfer chamber 42.
This has the benefit that there would be no worry about
"overfilling" each transfer chamber 42 with propellant 12, and no
propellant 12 would be directly lost through exhaust conduit 34. It
further has the benefit that there would be no worry about feeding
pressurant 20 directly to the engine 2 via engine conduit 32. Any
pressurant 20 that made it to the engine 2 could interrupt
combustion and possibly fail the engine.
[0051] Referring now to FIG. 16, in another preferred embodiment,
spindle 26 contains a plurality of very thin transfer chambers 84.
It is the same as the spindle 26 described previously, except for
the existence of thin transfer chambers 84. The thinner the thin
transfer chambers 84, the fewer the instabilities--e.g. splashing
of propellant 12, bubbles of pressurant 20 in propellant 12,
unevenness of the meniscus of propellant 12, etc. One might
conceive of a thin transfer chamber 84 so thin that propellant 12
is fed into it by means of a capillary effect. This is all within
the scope of the present invention.
[0052] Referring now to FIGS. 17 and 18, in another preferred
embodiment, spindle 26 houses several transfer chambers 42', each
of which contains a movable membrane 74 that is capable of
separating a region above it from a region below it. The membrane
74 serves a similar purpose as piston 72 shown in FIG. 15, except
that the edges of membrane 74 are permanently attached to the walls
of transfer chamber 42', so that there is no need to provide a
moving seal between the membrane 74 and the walls of transfer
chamber 42'. Rather, while the edges of membrane 74 stay fixed in
relation to the transfer chamber 42', the remainder of the membrane
74 (particularly near the center) moves up and down in the transfer
chamber 42' in response to the filling and draining of propellant
12 per the cycle previously described. This embodiment, like the
embodiment involving piston 72, has the advantage that membrane 74
would prevent the direct feeding of propellant 12 to exhaust
conduit 34 and the direct feeding of pressurant 20 to engine
conduit 32.
[0053] It will be apparent to one skilled in the art that the
transfer chamber 42 need not be housed in a spindle 26, need not
rotate with the spindle 26, and need not be in a cycle of rotation
at all--it could move in many other cyclical ways relative to the
conduits 6, 32, 34, 36 and chamber separators 28, 30. By way of
example and not of limitation, a transfer chamber could reciprocate
between the pressurant conduit 36/engine conduit 32 pair and the
exhaust conduit 34/propellant conduit 6 pair. In order to provide
constant, uninterrupted flow to the engine 2 via engine conduit 32,
several such reciprocating transfer chambers 42 could be used in
parallel, each one corresponding to a different stage in the cycle.
In all cases, however, at least one transfer chamber 42 moves in a
cycle to transfer a propellant/fluid from a filling stage to a
pressurizing/emptying stage.
* * * * *