U.S. patent application number 14/732620 was filed with the patent office on 2015-12-10 for liquid pump.
The applicant listed for this patent is LightSail Energy, Inc.. Invention is credited to Edwin P. BERLIN, JR., Danielle A. FONG, Philip Le Roux, AmirHossein POURMOUSA ABKENAR.
Application Number | 20150354556 14/732620 |
Document ID | / |
Family ID | 54767486 |
Filed Date | 2015-12-10 |
United States Patent
Application |
20150354556 |
Kind Code |
A1 |
FONG; Danielle A. ; et
al. |
December 10, 2015 |
LIQUID PUMP
Abstract
Embodiments relate to architectures for pumps responsible for
introducing liquid into cylinders reversibly configurable to
perform gas compression or expansion. Particular embodiments
maintain liquid flow rates in the face of the different pressure
profiles (.DELTA.-P) encountered during various portions of gas
compression and gas expansion cycles. In some embodiments, the pump
comprises multiple pumping elements per cylinder, at least one
pumping element separable with a clutch and designed to spray/not
spray during portions of compression/expansion cycles. Embodiments
may employ phase difference(s) between the multiple pumping
elements to introduce liquid in a desired manner. Mechanisms
allowing adjustment in phase of multiple pumping elements, are also
disclosed. The liquid may be introduced through sprayers arranged
in rings in the cylinder, with rings (or partitions thereof)
dedicated to spraying during different portions of compression
and/or expansion. Embodiments may flow liquid to a gas
compression/expansion cylinder via an intervening chamber of
changeable volume.
Inventors: |
FONG; Danielle A.; (Oakland,
CA) ; POURMOUSA ABKENAR; AmirHossein; (Walnut Creek,
CA) ; BERLIN, JR.; Edwin P.; (Oakland, CA) ;
Le Roux; Philip; (Berkeley, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LightSail Energy, Inc. |
Berkeley |
CA |
US |
|
|
Family ID: |
54767486 |
Appl. No.: |
14/732620 |
Filed: |
June 5, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62008706 |
Jun 6, 2014 |
|
|
|
Current U.S.
Class: |
417/374 |
Current CPC
Class: |
F04B 53/16 20130101;
F04B 53/10 20130101; F04B 37/00 20130101; F04B 35/01 20130101; F04B
9/042 20130101; F04B 23/06 20130101; F04B 49/125 20130101; F04B
53/14 20130101 |
International
Class: |
F04B 49/12 20060101
F04B049/12; F04B 53/14 20060101 F04B053/14; F04B 53/10 20060101
F04B053/10; F04B 53/16 20060101 F04B053/16; F04B 35/01 20060101
F04B035/01; F04B 37/00 20060101 F04B037/00 |
Claims
1. An apparatus comprising: a liquid pumping element in fluid
communication with a cylinder and coupled via a phaser to a
crankshaft of a reciprocating member, such that a timing of liquid
injection into the cylinder in an absence of combustion can be
adjusted relative to a location of the reciprocating member within
the cylinder.
2. An apparatus as in claim 1 wherein the reciprocating member
within the cylinder defines a gas compressor.
3. An apparatus as in claim 1 wherein the reciprocating member
within the cylinder defines a reversible compressor/expander.
4. An apparatus as in claim 1 wherein the phaser comprises a
planetary gear set.
5. An apparatus as in claim 1 wherein the liquid pumping element
comprises a cam.
6. An apparatus as in claim 5 wherein a shape of the cam produces a
liquid injection event occupying a smaller crank angle range than a
liquid intake event.
7. An apparatus as in claim 5 wherein a shape of the cam determines
a spray profile.
8. An apparatus as in claim 1 wherein the liquid pumping element
comprises a plunger within a sleeve.
9. An apparatus as in claim 8 lacking a seal between the plunger
and the sleeve.
10. An apparatus as in claim 1 wherein the liquid pumping element
further comprises a spring.
11. An apparatus as in claim 1 wherein the liquid pumping element
is in fluid communication with a ring of liquid sprayers arranged
in a cylinder wall.
12. An apparatus as in claim 11 wherein the cylinder comprises a
single piece.
13. An apparatus as in claim 11 wherein the timing of liquid
injection into the cylinder is adjusted to avoid spraying when the
reciprocating member covers the ring of liquid sprayers.
14. An apparatus as in claim 11 wherein the liquid pumping element
is in fluid communication with a plurality of rings of liquid
sprayers arranged in the cylinder wall.
15. An apparatus as in claim 14 wherein the plurality of rings are
bunched near Top Dead Center (TDC).
16. An apparatus as in claim 1 further comprising a spline coupling
the liquid pumping element to the crankshaft.
17. A method comprising: placing a pumping element in mechanical
communication with a crankshaft of a reciprocating member to flow
liquid to a sprayer in a cylinder wall in an absence of combustion;
and adjusting a phase of the pumping element relative to the
crankshaft.
18. A method as in claim 17 wherein: the pumping element comprises
a plunger in mechanical communication with the crankshaft via a
cam; and adjusting the phase of the pumping element comprises
actuating the cam with a planetary gear.
19. A method as in claim 17 wherein a shape of the cam results in a
liquid injection event occupying a smaller crank angle range than a
liquid intake event.
20. A method as in claim 17 wherein a shape of the cam results
determines a spray profile.
21. A method as in claim 17 further comprising biasing the pumping
element with a spring.
22. A method as in claim 17 wherein the sprayer is arranged in one
of a plurality of rings of a cylinder wall comprising a single
piece.
23. A method as in claim 17 wherein the phase of the pumping
element is adjusted to avoid spraying when a piston covers the
sprayer.
24. A method as in claim 22 wherein the plurality of rings are
bunched proximate to Top Dead Center (TDC).
25. A method as in claim 17 wherein the phase is adjusted according
to a pressure ratio.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The instant nonprovisional patent application claims
priority to U.S. Provisional Patent Application No. 62/008,706
filed Jun. 6, 2014 and incorporated by reference in its entirety
herein for all purposes.
BACKGROUND
[0002] Under certain circumstances, it may be desirable to
introduce liquid into gaseous environments experiencing changes in
pressure.
SUMMARY
[0003] Embodiments relate to architectures for pumps responsible
for introducing liquid into cylinders reversibly configurable to
perform gas compression or expansion. Particular embodiments
maintain liquid flow rates in the face of the different pressure
profiles (A-P) encountered during various portions of gas
compression and gas expansion cycles. In some embodiments, the pump
comprises multiple pumping elements per cylinder, at least one
pumping element separable with a clutch and designed to spray/not
spray during portions of compression/expansion cycles. Embodiments
may employ phase difference(s) between the multiple pumping
elements to introduce liquid in a desired manner. Mechanisms
allowing adjustment in phase of multiple pumping elements, are also
disclosed. The liquid may be introduced through sprayers arranged
in rings in the cylinder, with rings (or partitions thereof)
dedicated to spraying during different portions of compression
and/or expansion. Embodiments may flow liquid to a gas
compression/expansion cylinder via an intervening chamber of
changeable volume.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 are plots showing pressure and water flow rate versus
crank angle for gas compression and expansion cycles taking place
respectively, within a cylinder.
[0005] FIG. 2 is a simplified view of a liquid pump according to an
embodiment.
[0006] FIG. 3 is a simplified view of a liquid pump according to an
embodiment.
[0007] FIG. 4 is a simplified view of a liquid pump according to an
embodiment.
[0008] FIG. 5 is a simplified view of a liquid pump according to an
embodiment, comprising multiple pumping elements operating in
different phases.
[0009] FIG. 6 is a simplified view of a mechanism for a liquid pump
according to an embodiment, that allows adjustment in phase.
[0010] FIGS. 7-7D show an embodiment configured to flow liquid to a
gas compression/expansion cylinder via an intervening chamber
having a changeable volume.
[0011] FIG. 8 shows an alternative embodiment of a chamber
comprising a plurality of sprayers formed in a single integral
piece.
[0012] FIG. 9 shows the pump for the particular chamber embodiment
of FIG. 8.
[0013] FIG. 10 shows spray profiles in a compression runs utilizing
four of the nine spray rings of the chamber of FIG. 8.
[0014] FIG. 11 plots efficiency across a range of pressure ratios
(PRs) for optimized spray timings.
DESCRIPTION
[0015] Incorporated by reference in its entirety herein for all
purposes, is U.S. Patent Publication No. 2011/0115223 ("the '223
Publication"). The '223 Publication discloses that gas may be
compressed and/or expanded in the presence of a liquid heat
exchange medium. That is, heat generated from the compression of
gas is transferred across a gas-liquid boundary (e.g. fine
droplets), such that the temperature experienced by the gas remains
within a relatively small range over the course of the course of
the compression cycle. This enhances the thermodynamic efficiency
of the storage of energy by compression. During expansion, heat may
be transferred across a gas-liquid boundary (e.g. fine droplets) to
heat expanding gas, such that the temperature experienced by the
gas remains within a relatively small range over the course of the
expansion cycle. This enhances the thermodynamic efficiency of the
recovery of energy by expansion.
[0016] A compressor and/or expander as described in the '223
Publication, may utilize a reciprocating or rotating moveable
member for gas compression. An example of the former is a solid
piston connected to a mechanical linkage comprising a piston rod
and rotating shaft (e.g. crankshaft). An example of the latter is a
rotating turbine, screw, or other structure connected to a
mechanical linkage comprising a rotating shaft.
[0017] In certain embodiments as described in the '223 Publication,
liquid may be introduced directly into the compression/expansion
chamber for heat exchange. In certain embodiments, liquid may be
introduced to gas in a mixing chamber upstream of the
compression/expansion chamber.
[0018] The '223 Publication discloses that in certain embodiments,
the same cylinder structure may be configurable to selectively
perform gas expansion and gas compression. The number and type of
liquid sprayers (nozzles) present in such a reversible cylinder
structure will generally be fixed (e.g. sprayers will not easily be
removable or their positions altered between compression and
expansion cycles).
[0019] Such a fixed configuration, however, may present an issue
with changing water flow rate and not changing the type or number
of sprayers. In particular, as explained in connection with FIG. 1
below, the .DELTA.P across sprayers will be different for
compression and expansion. This situation is not ideal from an
efficiency standpoint.
[0020] Incorporated by reference in its entirety herein for all
purposes, is U.S. Patent Publication No. 2013/0098027 ("the '027
Publication"). The '027 Publication discloses certain architectures
which may be used to introduce liquid for heat exchange with
expanding gas or gas that is being compressed within a chamber.
[0021] Embodiments described herein, relate to pump architectures
that are responsible for introducing liquid into cylinders that are
reversibly configurable to perform gas compression or gas
expansion. Particular embodiments maintain liquid flow rates in the
face of the different pressure profiles (A-P) encountered during
various phases of gas compression and gas expansion processes. In
certain embodiments the pump comprises multiple pumping elements
per cylinder, at least one pumping element separable with a clutch
and designed to spray or not spray during the compression or
expansion modes.
[0022] As further discussed below in connection with FIG. 5, in
certain embodiments the multiple pumping elements may be operated
by different cam sets in order to enhance efficiency.
[0023] Other embodiments may dispense with a clutch in favor of a
split water pump having multiple stages (at least one of which
having a phase adjustment device). Such a configuration may enhance
efficiency.
[0024] Liquid may be introduced through sprayers arranged in rings
in the cylinder. The rings (or partitions thereof) may be dedicated
to spraying at different times.
[0025] FIG. 1 shows plots of pressure and water flow rate through
nozzles, versus crank angle, for gas compression and expansion
cycles taking place within a cylinder. FIG. 1 shows that the
compression cycle experiences maximum benefit from the spraying of
liquid for heat exchange at different times and at different points
than the expansion cycle.
[0026] For example, FIG. 1 shows that for the compression cycle,
the greatest change (increase) in pressure occurs at a crank angle
of about 270.degree.. In order to ensure a uniform of distribution
of fine liquid droplets to absorb heat at this point of the
compression cycle, the period of liquid spraying (shown as .fwdarw.
in FIG. 1) should commence at some point earlier than the crank
angle of 180.degree.. This upper plot of FIG. 1 also shows how the
flow rate of injected liquid water may change over time, in order
to achieve desired heat exchange in compression.
[0027] Conversely, FIG. 1 shows that for the expansion cycle, the
greatest change (decrease) in pressure occurs at a crank angle of
about 90.degree.. In order to ensure that a uniform distribution of
fine liquid droplets is available in the cylinder to transfer heat
at this point of the expansion cycle, the period of liquid spraying
(shown as .fwdarw. in FIG. 1) should commence well before a crank
angle of 90.degree.. The lower plot of FIG. 1 also shows how the
flow rate of injected liquid water may change over time, in order
to achieve desired heat exchange in expansion.
[0028] To accommodate the different demands of liquid spraying
encountered in compression versus expansion cycles, various pump
architectures are described. FIG. 2 is a simplified view of a
liquid pump according to one embodiment.
[0029] Specifically, liquid pump 200 comprises a first pumping
element 202 and a second pumping element 204 driven by a pump drive
mechanism 206. The first pumping element and the second pumping
element are in fluid communication with manifolds 208 that surround
rings of sprayers 210 arrayed to introduce liquid for heat exchange
with gas within cylinder 212.
[0030] A moveable element 214 comprising a solid piston is disposed
within the cylinder. The solid piston is coupled to a rotating
crankshaft 216 by a piston rod 218. In this particular figure, the
piston rod is shown connected directly to the crankshaft.
Alternative configurations are possible, however, including the use
of an intervening cross-head.
[0031] In compression, the crankshaft is placed in communication
with a source of shaft torque to drive the piston to compress gas
within the cylinder. In expansion, the crankshaft is rotated by gas
expanding within the cylinder to drive the solid piston and the
piston rod.
[0032] Second pumping element 204 is selectively disengageable from
the pump drive mechanism by a clutch 220, in order to spray or not
spray at particular times during the compression or expansion
modes. In particular, in this particular embodiment the second
pumping element 204 is in fluid communication with the top two
rings only.
[0033] During compression, the second pumping element is disengaged
from the pump drive mechanism by the clutch. Accordingly, spraying
occurs in lower cylinder regions in a manner calculated to
accomplish heat absorption with the greatest effect (see top plot
of FIG. 1).
[0034] By contrast, during expansion the second pumping element is
engaged with the pump drive mechanism by the clutch. As a result of
this configuration, additional spraying occurs at regions of the
cylinder near TDC in a manner calculated to accomplish heat
transfer with the greatest effect (see bottom plot of FIG. 1).
[0035] While the above discussion has focused upon the use of a
clutch to accomplish water pumping in the manner desired, this is
not required. Alternative embodiments could utilize other types of
mechanisms for this purpose. Examples of such mechanisms can
include but are not limited to reversing gears and phasers.
[0036] As FIG. 1 shows, liquid spraying may be performed during a
different range of crank angles for compression and expansion
processes. As the spray pulse is nearly symmetric, this could be
accomplished by changing the phase of the pump relative to the
compressor/expander crankshaft.
[0037] Such a phase change could be achieved using a planetary gear
set as shown in FIG. 6. This system has an input shaft coupled to
the main crankshaft, an output shaft coupled to the pump, and a
control input which is arranged to change the phase between the
main crank and the pump. This arrangement permits continuous
variation of the phase, which further allows for optimizing
efficiency over a range of operating conditions.
[0038] It is also possible to operate the pump by reversing the
direction of rotation of the pump camshaft. A reversing gear may be
arranged to reverse the pump camshaft direction relative to a
particular crank angle and thus give one spray phase for
compression and another for expansion. While such an arrangement
does not allow for continuous adjustment of the phase, it may be
less expensive than a planetary gear set.
[0039] It may be possible to operate not only the pump, but also
the compressor/expander with either direction of shaft rotation. In
such a case, the entire machine may be reversed without the need
for additional gearing. For example, if the machine is connected to
a three-phase motor/generator, electrically swapping a pair of
electrical phases to that device will reverse its direction.
[0040] FIG. 5 shows an example of a pumping apparatus 500
comprising a plurality of piston pumps 502a-c that are actuated by
different cams 504a-c. While rotation of each of the cams is
synchronized relative to a crankshaft of the compression and/or
expansion cylinder, each of the cams is configured to be in a
different phase relative to the other.
[0041] Utilizing such ganged operation of multiple pumping elements
in different phases, an overall pumping profile having a desired
character can be achieved. Such a pumping profile can be integrated
to result in pumping in the desired manner in one or more regions
(e.g. rings) present within a compression and/or expansion
cylinder.
[0042] It is noted that the shape of the cams dictates the timing
of the events triggered by rotation thereof. Thus, the cam could be
shaped such that a liquid injection event occurs quickly, over a
relatively short span of the 360.degree. rotation angle, with the
remainder occupied by a liquid intake event. As discussed later on,
such a configuration could serve to help reduce cavitation and
avoid wear on the pump.
[0043] It is further noted that the return mechanism for the
plunger/pistons can comprise a spring. Alternatively, the
plunger/pistons of the pump could be coupled to opposing plungers
and operate according to a desmodromic-type actuation scheme.
[0044] Returning back to FIG. 2, while that particular embodiment
shows the pumping elements as being in fluid communication with
manifolds that surround all sprayers of a particular ring, this is
not required. Alternative embodiments could employ partitioning of
the rings. Such an approach is shown in FIG. 3.
[0045] In particular, FIG. 3 shows an alternative embodiment of a
pump 300 in which some of the sprayers 302 ("expansion" sprayers)
on a ring are connected to the second pumping element 307, and the
rest of the sprayers 304 ("compression" sprayers) on the ring are
connected to the first pumping element 305.
[0046] A clutch 309 is used to selectively disengage the pumping
elements from the pump drive mechanism. In particular, during
compression, liquid is sprayed through "compression" sprayers by
the first pumping element. During expansion, liquid is sprayed
through "expansion" sprayers by the second pumping element.
[0047] In the specific embodiment shown in FIG. 3, depending upon
the location of a particular ring within the cylinder, it may
comprise a higher or lower proportion of compression or expansion
sprayers. A ring closer to TDC is partitioned into a larger
proportion of expander sprayers. A ring closer to BDC is
partitioned into a smaller proportion of expander sprayers.
[0048] FIG. 4 is a simplified view of a liquid pump 400 according
to another embodiment. The particular embodiment of FIG. 4 has a
first (baseline) pumping element 402 that sprays during both
compression and expansion.
[0049] The particular embodiment of FIG. 4 also has a second
(adjustable) pumping element 404 that selectively adds to the
baseline flow of heat exchange liquid. In particular, this second
pumping element pumps more into upper rings during expansion, and
pumps more into center rings during compression.
[0050] This adjustability characteristic of the second pumping
element depending upon operational mode, may be achieved in a
variety of ways. One approach is to change the position of a 3-way
valve 406 as in FIG. 4.
[0051] Another approach is to change the phase of the spray. FIG. 6
shows an embodiment of a mechanism 600 that could be employed to
change spray phase. Specifically, the mechanism could comprise a
cam 602 in communication with a camshaft 604. Selective rotation of
a planetary gear 606 by worm gear 608 (e.g. utilizing a stepper
motor or other actuator) allows change in the position/phase of the
cam lobe relative to the cam shaft.
[0052] Different embodiments may employ varying architectures. For
example, particular embodiments may utilize a split water pump with
at least two groups of stages. No clutch is used, but at least one
of the stages has a phase adjustment device, to maximize
efficiency.
[0053] Alternative liquid pumping architectures are possible. For
example, certain embodiments could employ a configuration in which
liquid is flowed to the gas compression/expansion cylinder via an
intervening chamber having a changeable volume. One embodiment of
such a pumping scheme is shown in FIGS. 7-7D.
[0054] Specifically, one embodiment of a pumping apparatus is shown
in FIG. 7. Specifically, the pumping apparatus 700 comprises a
constant flow pump 702 that is in fluid communication with a gas
compression and/or expansion chamber 704 via intervening liquid
chamber 706.
[0055] The intervening liquid chamber 706 is defined within
stationary walls 708. The intervening liquid chamber 706 is also
defined within a moveable wall 710 to define a changing volume.
Here, the chamber wall 710 comprises a piston 712 that is in
communication with a linkage 714 (here, a mechanical linkage in the
form of a crankshaft).
[0056] In this embodiment, movement of the linkage and the
corresponding location of the moveable wall 710 is coordinated with
the pressure inside the gas compression/expansion chamber, to
result in a substantially constant flow of liquid therein. In
certain embodiments, this coordinated movement may be accomplished
by providing a further mechanical linkage 716 between the
crankshaft of the gas compression/expansion chamber, and the
mechanical linkage 714 of the liquid chamber.
[0057] According to other embodiments, this coordinated movement
can be accomplished without providing such a mechanical linkage.
For example, in certain embodiments the linkage 714 may be operated
based upon timed inputs received from a processor, e.g., according
to a Phase Lock Loop (PLL), or Voltage Controlled Oscillation (VCO)
or Proportional-Integral-Derivative (PID) control schemes.
[0058] Operation of the pumping apparatus of FIG. 7 is now
described in connection with FIGS. 7A-7D. In particular, as shown
in FIG. 7A as the piston of the gas compressor approaches TDC at
the end of the compression stroke, the gas pressure in the gas
chamber is high. Absent an increase in the pressure of the liquid
being injected, the flow rate of the liquid would fall, adversely
affecting the quality of the heat exchange occurring in the
chamber.
[0059] Accordingly, FIG. 7A shows that at this time the available
volume in the intervening liquid chamber would also fall. This
would increase the liquid pressure at the time when gas pressure is
increasing within the cylinder, maintaining flow rate and
gas-liquid heat exchange.
[0060] Conversely, FIG. 7B shows that as the piston of the gas
compressor recedes from TDC toward BDC during the intake stroke,
the pressure of the gas in the compression chamber is lower. Thus
during this portion of the compression cycle, the volume available
to the liquid in the intervening chamber would increase. This would
in turn reduce the liquid pressure at the time when gas pressure
also falling within the cylinder, again maintaining liquid flow
rate and consistent gas-liquid heat exchange within the
chamber.
[0061] FIGS. 7C-7D show the situation during expansion and
expansion cycle. At the beginning of the expansion stroke, the gas
pressure within the cylinder is at its highest. In order to
maintain liquid flow and hence the quality of gas-liquid heat
exchange during this period, FIG. 7C shows that the volume
available to the intervening liquid chamber is low.
[0062] Conversely, as the piston continues to move toward BDC
during the remainder of the expansion stroke, the available volume
of the intervening chamber would increase, thereby reducing the
liquid pressure to match the gas pressure. Liquid flow rate, and
hence the quality of gas-liquid heat exchange during expansion, is
thereby maintained.
[0063] The character in the change of volume available to the
intervening liquid chamber over time, need not be symmetrical
relative to high liquid pressure (e.g. the TDC position). In fact,
the shape of the liquid pressure profile could be determined by
factors such as cam shape (in the case of a mechanical linkage), or
alternatively under the influence of some other factor (e.g. field
strength in the case of an electro-mechanical linkage). Hydraulic
linkages to control the location of the moveable wall of the
intervening chamber are also possible.
[0064] In the particular embodiment of FIG. 7, under certain
conditions the pump will act as a net consumer of energy (e.g. to
introduce liquid into the compression/expansion chamber at higher
pressures). However, it is further noted that at other portions of
the cycle the pump may be able to recoup energy.
[0065] That is, during certain times the constant flow pump may be
flowing liquid into the chamber, while the volume available in the
liquid chamber is increasing. Under such circumstances, the energy
is recovered from driving the linkage by the liquid entering the
intervening chamber. Such energy can be harnessed by placing the
linkage into communication with a generator or motor-generator.
[0066] Some embodiments are now described in the following
clauses.
[0067] 1. An apparatus comprising:
[0068] a first pumping element coupled to a pump drive mechanism
and in fluid communication with a first liquid sprayer of a
cylinder having a solid piston disposed therein, the first pumping
element configured to spray a liquid into the cylinder during gas
compression; and
[0069] a second pumping element coupled to the pump drive mechanism
and in fluid communication with a second liquid sprayer of the
cylinder, the second pumping element selectively coupled to the
pump drive mechanism via a first clutch to spray the liquid into
the cylinder during gas expansion.
[0070] 2. An apparatus as in claim 1 wherein the first liquid
sprayer is in communication with the first pumping element via a
liquid manifold.
[0071] 3. An apparatus as in clause 2 wherein the first liquid
sprayer shares the manifold with a third liquid sprayer.
[0072] 4. An apparatus as in clause 3 wherein the first liquid
sprayer and the second liquid sprayer are arrayed as part of a
first ring.
[0073] 5. An apparatus as in clause 4 wherein:
[0074] the second liquid sprayer is arrayed as part of the first
ring; and
[0075] the first ring is partitioned.
[0076] 6. An apparatus as in clause 1 wherein the first liquid
sprayer is arrayed as part of a first ring, and the second liquid
sprayer is arrayed as part of a second ring.
[0077] 7. An apparatus as in clause 1 wherein a gas flow valve is
located near Top Dead Center (TDC) of the cylinder, and the second
liquid sprayer is positioned closer to TDC than the first liquid
sprayer.
[0078] 8. An apparatus as in clause 1 wherein the second pumping
element is selectively coupled to the pump drive mechanism via a
second clutch to spray the liquid into the cylinder during the gas
compression.
[0079] 9. An apparatus as in clause 1 wherein the first pumping
element comprises a mechanism to control a spray phase.
[0080] 10. An apparatus as in clause 1 wherein the first pumping
element comprises a first cam and the second pumping element
comprises a second cam.
[0081] 11. An apparatus comprising:
[0082] a first pumping element coupled to a pump drive mechanism
and in fluid communication with a first liquid sprayer of a
cylinder having a solid piston disposed therein, the first pumping
element configured to spray a liquid into the cylinder during gas
compression; and
[0083] a second pumping element coupled to the pump drive mechanism
and in fluid communication with a second liquid sprayer of the
cylinder, the second pumping element selectively coupled to the
pump drive mechanism via a phase adjustment mechanism to spray the
liquid into the cylinder during gas expansion.
[0084] 12. An apparatus as in clause 11 wherein the phase
adjustment mechanism comprises a cam selectively moveable relative
to a rotating camshaft via a planetary gear set.
[0085] 13. An apparatus as in clause 12 wherein:
[0086] the second pumping element comprises a piston; and
[0087] the phase adjustment mechanism comprises the cam selectively
moveable relative to the rotating camshaft via a gear system.
[0088] 14. An apparatus as in clause 13 wherein the gear system
comprises a worm gear and a planetary gear.
[0089] 15. A method comprising:
[0090] causing a first pumping element of a pump to flow liquid to
a first liquid sprayer of a cylinder having a solid piston disposed
therein in communication with a crankshaft, the first pumping
element configured to spray a liquid into the cylinder during gas
compression; and
[0091] causing a second pumping element of the pump to flow liquid
to a second liquid sprayer of the cylinder during gas
expansion.
[0092] 16. A method as in clause 15 wherein the first pumping
element and the second pumping element are in communication with
the crankshaft.
[0093] 17. A method as in clause 16 wherein the second pumping
element is in selective communication with the crankshaft via a
clutch.
[0094] 18. A method as in clause 16 wherein a phase of the second
pumping element is adjustable relative to a phase of the first
pumping element.
[0095] 19. A method as in clause 18 wherein the phase of the second
pumping element is adjustable by rotation of a cam relative to a
camshaft via a planetary gear set.
[0096] 20. A method as in clause 15 wherein the first pumping
element is also configured to spray into the cylinder during gas
expansion.
[0097] 21. A method as in clause 15 wherein the second pumping
element is also configured to spray into the cylinder during gas
compression.
[0098] 22. An apparatus comprising:
[0099] a liquid flow pumping element in liquid communication with a
gas chamber receiving a reciprocating member, via an intervening
liquid chamber having a changeable volume, wherein the intervening
liquid chamber is configured to maintain a substantially constant
pressure of liquid injected into the gas chamber.
[0100] 23. An apparatus as in clause 22 wherein the changeable
volume of the intervening liquid chamber is determined by movement
of a piston in communication with a linkage.
[0101] 24. An apparatus as in clause 23 wherein the linkage is in
physical communication with the reciprocating element within the
gas chamber.
[0102] 25. An apparatus as in clause 23 wherein the linkage is in
communication with a motor or a motor-generator.
[0103] 26. An apparatus as in clause 22 wherein the changeable
volume of the intervening liquid chamber is determined by movement
of an elastic membrane.
[0104] 27. An apparatus as in clause 22 wherein the flow pumping
element comprises a rotary pump.
[0105] It is noted that the above description relates to only
certain embodiments, variations of which are possible. For example,
FIG. 8 shows an alternative embodiment of a chamber, this time
comprising a plurality of sprayers formed in a single integral
piece.
[0106] In particular, the chamber of FIG. 8 includes seven (7)
spray rings with forty-five (45) nozzle locations each. The piston
is not shown in this view for clarity of illustration.
[0107] Converting the cylinder into a single piece containing seven
(7) rows, provides the benefit of greater mechanical integrity, and
reduces the cost of fabrication. It also allows for tighter radial
clearances between the piston and cylinder wall, reducing the
geometric dead volume in the cylinder. Each plenum is separated
internally by o-rings, so their pressures are independent.
[0108] This embodiment also features the spray rings bunched
together near TDC. This configuration allows each ring to spend
more time uncovered by the piston during the cycle.
[0109] Locating spray rings near TDC also concentrates spray
delivery in the portion of the chamber where heat exchange will
have its greatest effect. That is, on compression the greatest
temperature increase is expected to occur proximate to TDC as the
gas is compressed to its output pressure, while on expansion the
greatest temperature drop is also expected to occur proximate to
TDC as the gas undergoes initial expansion from its inlet
pressure.
[0110] The pump for the particular embodiment of FIG. 8 is shown in
FIG. 9. This pump features twelve (12) plungers capable of 122.7
g/rev total water flow (1.23 kg/s@600 RPM). In this particular
embodiment, the plungers are not in contact with a seal, but in
other embodiments a wiping seal could be used.
[0111] The pump includes several features designed to improve
performance. For example compliance and length of the spray lines
is reduced in order to achieve the sharpest possible spray pulse
shape.
[0112] The embodiment of FIG. 9 also features decoupled opposing
plungers. In particular, the plunger design was switched to a
spring-actuated plunger return, allowing motion of each plunger to
be controlled independently. This was particularly relevant to
reducing the intensity of the fill stroke to reduce cavitation by
avoiding relative pressures below the vapor pressure of water, a
situation which can give rise to cavitation and wear.
[0113] The profiles of the pump cams were changed to make the
plunger fill strokes less aggressive (i.e., occurring over a larger
crank angle range) in an effort to reduce cavitation. On injection,
more aggressive (i.e., occurring over a smaller crank angle range)
cam profiles were optimized to achieve the desired step-profile for
spray injection, thereby allowing concentrated spray "on demand" at
certain portions of the cycle.
[0114] One or more factors may be considered in determining an
optimum spray profile under particular circumstances. Examples of
such factors can include but are not limited to, flow rate across
the nozzle, droplet size, injection velocity, and structure (e.g.,
3-D shape) of the resulting spray plume.
[0115] Pump chamber refill considerations may also play a role. For
example, injection over a minority of crank angle can leave the
remaining majority of the cycle available for liquid intake into
the pump chamber. Such an approach can lessen pressure
differentials arising in the pump, reducing cavitation and
wear.
[0116] FIG. 10 plots (normalized) pressure across the nozzles of
the seven spray rings shown in FIG. 8, versus crank angle for
various compression runs. The spray profiles detailed in FIG. 10
show some of the spray rings (e.g., rings 1-5) in fluid
communication with multiple cam lobes of the pump--as in the
configuration previously illustrated in connection with FIG. 5.
Other of the spray rings (e.g., rings 6-7) are in fluid
communication with only one respective cam lobe of the pump.
[0117] It is further noted that the pump embodiment of FIG. 9
features plungers of different sizes in communication with the
various spray rings. For example, plungers of larger diameters may
achieve a higher flow rate supplying spray rings at a lower
pressure (e.g., further away from TDC). Conversely, smaller
diameter pump plungers (capable of exerting more concentrated
forces) may be used to supply the highest pressure spray rings
located near TDC.
[0118] FIG. 10 further illustrates another aspect of cam design in
the embodiment of the liquid flow pump of FIG. 8. That is, the cam
lobes may be shaped to substantially reduce an amount of liquid
that is flowed to a spray ring when the piston is overlapping.
[0119] Specifically, occlusion of the spray ring by the piston will
prevent small droplet formation, instead resulting in the
introduction of bulk water offering a small gas-liquid interface
and poor heat exchange properties. And, this introduction of such
bulk water consumes power, serving as a drag on efficiency.
[0120] Accordingly, the spray profiles of FIG. 10 show low
pressures across the nozzles at crank angles when the piston is
located at or near the spray ring. For example, FIG. 10 shows the
pressure across a nozzle of ring 7, dropping at a crank angle of
about 290.degree. as the piston passes by (shown by the vertical
line). This result is accomplished by the shape of lobe 11.
[0121] Spray ring 1 located much nearer to TDC, also experiences a
drop in pressure owing to the shape of lobes 5 and 6. Here the
pressure begins to drop as the piston approaches, before it
actually reaches the spray ring (shown by the solid vertical line).
Such a pressure profile can avoid or reduce a volume of liquid that
is sprayed while the exhaust valve is open to flow compressed gas
from the cylinder.
[0122] In one embodiment the mechanical connection between the pump
of FIG. 10 and the drive train of the compression/expander piston,
is a spline coupling with 34 gear teeth. This corresponds to each
spline position being offset by 10.6.degree..
[0123] In order to study performance effects of sweeping spray
timing, the following five spline positions were tested (in
addition to the nominal 0.degree. offset): -42.4.degree.;
-31.8.degree.; -21.2.degree.; -10.6.degree.; and +10.6.degree.. The
timing was thus advanced to the point where the start of the spray
corresponded to the low pressure valve closing event. The timing
was also retarded by one position from nominal to investigate the
effect on high PR conditions.
[0124] Compression Power One Way (CPOW) efficiency was then
calculated using the maximum One Way Efficiency (OWE) for any
spline position for each pressure ratio (PR). The resulting
difference in OWE across the range of PRs is shown in FIG. 11.
[0125] By adjusting the spline offset, it is possible to improve
OWE across the entire compression process. Thus in this example, a
phaser configured to vary the injection timing across the
compression event, could provide an improvement in CPOW by
0.6%.
[0126] In certain embodiments, actuation of the pump valves
relative to the drivetrain may be accomplished utilizing a Variable
Cam Phaser (VCP) structure available from Delphi Automotive PLC, of
Gillingham, U.K. That VCP allows a cam lobe (lift event) timing to
crank shaft timing to be changed, while the engine is operating,
based on the parameters of the engine.
[0127] The cam lobe angular position, or phase relationship, is
controlled by the internal vane mechanism of the VCP. Commands from
a control module can adjust the position of the valve.
* * * * *