U.S. patent application number 15/562374 was filed with the patent office on 2018-10-25 for air handling system constructions with externally-assisted boosting for turbocharged opposed-piston engines.
This patent application is currently assigned to ACHATES POWER, INC.. The applicant listed for this patent is ACHATES POWER, INC.. Invention is credited to SURAMYA D. NAIK, FABIEN G. REDON.
Application Number | 20180306144 15/562374 |
Document ID | / |
Family ID | 55697492 |
Filed Date | 2018-10-25 |
United States Patent
Application |
20180306144 |
Kind Code |
A1 |
REDON; FABIEN G. ; et
al. |
October 25, 2018 |
AIR HANDLING SYSTEM CONSTRUCTIONS WITH EXTERNALLY-ASSISTED BOOSTING
FOR TURBOCHARGED OPPOSED-PISTON ENGINES
Abstract
The air handling system of an opposed-piston engine is equipped
with an externally-assisted pumping element such as an
electrically-assisted compressor, an electrically-assisted
supercharger, or an electrically-assisted turbocharger.
Inventors: |
REDON; FABIEN G.; (SAN
DIEGO, CA) ; NAIK; SURAMYA D.; (SAN DIEGO,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ACHATES POWER, INC. |
San Diego |
CA |
US |
|
|
Assignee: |
ACHATES POWER, INC.
San Diego
CA
|
Family ID: |
55697492 |
Appl. No.: |
15/562374 |
Filed: |
March 22, 2016 |
PCT Filed: |
March 22, 2016 |
PCT NO: |
PCT/US2016/023602 |
371 Date: |
September 27, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62143917 |
Apr 7, 2015 |
|
|
|
62171918 |
Jun 5, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02B 2075/025 20130101;
F02B 39/10 20130101; Y02T 10/144 20130101; F02B 37/04 20130101;
Y02T 10/12 20130101; F02B 25/08 20130101; F02M 26/08 20160201; F02B
75/282 20130101; F02M 26/23 20160201; F01B 7/14 20130101; F02M
26/43 20160201 |
International
Class: |
F02M 26/08 20060101
F02M026/08; F01B 7/14 20060101 F01B007/14; F02B 25/08 20060101
F02B025/08; F02B 75/28 20060101 F02B075/28; F02B 37/04 20060101
F02B037/04; F02B 39/10 20060101 F02B039/10; F02M 26/23 20060101
F02M026/23 |
Claims
1. An air handling system for an opposed-piston engine, including
at least one cylinder with piston-controlled exhaust and intake
ports, comprising: a charge air channel coupled to provide charge
air to at least one intake port of the opposed-piston engine; an
exhaust channel coupled to transport exhaust gas from at least one
exhaust port of the opposed-piston engine; a turbocharger with a
turbine in the exhaust channel and a first compressor in the charge
air channel; and, an electrically-assisted compressor in the charge
air channel upstream of the first compressor, between a fresh air
inlet of the charge air channel and an inlet of the first
compressor.
2. The air handling system of claim 1, further including an EGR
loop including an inlet coupled to the exhaust channel, downstream
of an outlet of the turbine, and an outlet coupled to the charge
air channel, upstream of the electrically-assisted compressor.
3. The air handling system of claim 2, further including a charge
air cooler in the charge air channel between an outlet of the
electrically-assisted compressor and the inlet of the first
compressor.
4. The air handling system of claim 2, further including an
aftertreatment device in the exhaust channel, between an outlet of
the turbine and the EGR loop inlet.
5. (canceled)
6. The air handling system of claims 1-4, in which the charge air
channel includes first and second branches downstream of the first
compressor, the first and second branches have a common input
coupled to an outlet of the first compressor, and each branch
includes a respective charge air cooler.
7. The air handling system of claim 1, without an EGR loop.
8. The air handling system of claim 7, further comprising: a
valve-controlled bypass loop including an inlet in the charge air
channel, between the fresh air inlet and an inlet of the
electrically-assisted compressor, and an outlet in the charge air
channel, between the outlet of the electrically-assisted compressor
and the inlet of the first compressor; and a back pressure valve in
the exhaust channel, downstream of the turbine.
9. An air handling system for an opposed-piston engine including at
least one cylinder with piston-controlled exhaust and intake ports,
comprising: a charge air channel coupled to provide charge air to
at least one intake port of the opposed-piston engine; an exhaust
channel coupled to transport exhaust gas from at least one exhaust
port of the opposed-piston engine; a turbocharger with a turbine in
the exhaust channel and a first compressor in the charge air
channel; and, an electrically-assisted compressor in the charge air
channel downstream of the first compressor, between an outlet of
the first compressor and the at least one intake port.
10. The air handling system of claim 9, without an EGR loop.
11. The air handling system of claim 10, further comprising at
least one charge air cooler in the charge air channel, downstream
of the first compressor.
12. The air handling system of claim 11, in which the at least one
charge air cooler is in a portion of the charge air channel between
the outlet of the first compressor and an Inlet of the
electrically-assisted compressor.
13. The air handling system of claim 10, further comprising a
valve-controlled back flow prevention loop including an inlet in
the charge air channel, in common with an intake of the
electrically-assisted compressor, and an outlet in the charge air
channel, in common with the outlet of the electrically-assisted
compressor.
14. An air handling system for an opposed-piston engine including
at least one cylinder with piston-controlled exhaust and intake
ports, comprising: a charge air channel coupled to provide charge
air to at least one intake port of the opposed-piston engine; an
exhaust channel coupled to transport exhaust gas from at least one
exhaust port of the opposed-piston engine; a turbocharger with a
turbine in the exhaust channel and a compressor in the charge air
channel; an electrically-assisted supercharger in the charge air
channel downstream of the compressor, between an outlet of the
compressor and the at least one intake port; and, an EGR loop
including an inlet coupled to an exhaust port manifold in direct
fluid communication with at least one exhaust port and an outlet
coupled to the charge air channel, upstream of the
electrically-assisted supercharger.
15. The air handling system of claim 14, in which the charge air
channel includes first and second branches downstream of the
electrically-assisted supercharger, the first and second branches
have a common input coupled to an outlet of the
electrically-assisted supercharger, and each branch includes a
respective charge air cooler.
16. An air handling system for an opposed-piston engine, in which
the engine has no supercharger and includes at least one cylinder
with piston-controlled exhaust and intake ports, the air handling
system comprising: a charge air channel coupled to provide charge
air to at least one intake port of the opposed-piston engine; art
exhaust channel coupled to transport exhaust gas from at least one
exhaust port of the opposed-piston engine; an electrically-assisted
turbocharger with a turbine in the exhaust channel and a compressor
in the charge air channel; at least one charge air cooler in the
charge air channel, downstream of the compressor.
17. The air handling system of claim 16, further comprising a back
pressure valve in the exhaust channel, downstream of the
turbine.
18. The air handling system of claim 17, further including an EGR
loop including an inlet coupled to the exhaust channel, between the
back pressure valve and an outlet of the turbine, and an outlet
coupled to the charge air channel, upstream of the compressor.
19. The air handling system of claim 18, in which the turbine is a
variable geometry turbine.
20. The air handling system of claim 18, in which the charge air
channel includes first and second branches downstream of the
compressor, the first and second branches have a common input
coupled to an outlet of the compressor, and each branch includes a
respective charge air cooler.
21. The air handling system of claim 16, without an EGR loop.
Description
RELATED APPLICATIONS/PRIORITY
[0001] This application claims priority to U.S. Patent Application
Ser. No. 62/143,917, filed in the United States Patent Office on
Apr. 7, 2015 and U.S. Patent Application Ser. No. 62/171,918, filed
in the United States Patent Office on Jun. 15, 2015. This
application contains subject matter related to the subject matter
of commonly-owned U.S. patent application Ser. No. 13/782,802,
filed Mar. 1, 2013 for "EGR For A Two-Stroke Cycle Engine Without A
Supercharger", which was published as US 2013/0174548 A1 on Jul.
11, 2013. This application also contains subject matter related to
the subject matter of commonly-owned U.S. patent application Ser.
No. 13/891,622, filed May 10, 2013 for "Air Handling Constructions
With Turbo-Compounding For Opposed-Piston Engines", which was
published as US 2014/0331656 A1 on Nov. 13, 2014.
FIELD OF THE DISCLOSURE
[0002] The field is two-stroke cycle internal combustion engines.
Particularly, the field relates to uniflow-scavenged,
opposed-piston engines with air handling systems that provide
pressurized charge air for combustion and transport the products of
combustion. In some aspects, the field relates to
uniflow-scavenged, opposed-piston engines with air handling systems
that recirculate and mix exhaust gas with the pressurized charge
air in order to lower combustion temperatures.
BACKGROUND OF THE DISCLOSURE
[0003] A two-stroke cycle engine is an internal combustion engine
that completes a power cycle with a single complete rotation of a
crankshaft and two strokes of a piston connected to the crankshaft.
One example of a two-stroke cycle engine is an opposed-piston
engine in which two pistons are disposed in opposition in the bore
of a cylinder for reciprocating movement in opposing directions.
The cylinder has longitudinally-spaced inlet and exhaust ports
located near respective ends of the cylinder. Each of the opposed
pistons controls one of the ports, opening the port as it moves to
a bottom center (BC) location, and closing the port as it moves
from BC toward a top center (TC) location. One of the ports
provides passage of the products of combustion out of the bore, the
other serves to admit charge air into the bore; these are
respectively termed the "exhaust" and "intake" ports. In a
uniflow-scavenged opposed-piston engine, charge air enters a
cylinder through its intake port as exhaust gas flows out of its
exhaust port. Thus gas flows through the cylinder in a single
direction ("uniflow")--from intake port to exhaust port--to both
vacate the cylinder of exhaust gas and to resupply it with charge
air ("scavenging").
[0004] In FIG. 1, a two-stroke cycle internal combustion engine is
embodied by an opposed-piston engine 10 having at least one ported
cylinder 50. That is to say, the engine may have one ported
cylinder, two ported cylinders, three ported cylinders, or four or
more ported cylinders. Each cylinder 50 has a bore 52 and exhaust
and intake ports 54 and 56 formed or machined in respective ends of
a cylinder wall. Each of the exhaust and intake ports 54 and 56
includes one or more circumferential arrays of openings in which
adjacent openings are separated by a solid portion of the cylinder
wall (a "bridge"). In some descriptions, each opening is referred
to as a "port"; however, the construction of a circumferential
array of such "ports" is no different than the port constructions
shown in FIG. 1. In the example shown, the engine 10 further
includes two crankshafts 71 and 72. The exhaust and intake pistons
60 and 62 are slidably disposed in the bore 52 with their end
surfaces 61 and 63 opposing one another. The exhaust pistons 60 are
coupled to the crankshaft 71, and the intake pistons are coupled to
the crankshaft 72.
[0005] As the pistons 60 and 62 of a cylinder 50 near TC, a
combustion chamber is defined in the bore 52 between the end
surfaces 61 and 63 of the pistons. Fuel is injected directly into
the combustion chamber through at least one fuel injector nozzle 70
positioned in an opening through the sidewall of a cylinder 50. The
fuel is mixed with charge air compressed between the end surfaces,
and it ignites in response to the heat and pressure of the
compressed charge air. Combustion follows.
[0006] With further reference to FIG. 1, the engine 10 includes an
air handling system 80 coupled to intake and exhaust ports of the
opposed-piston engine that manages the transport of charge air
provided to, and exhaust gas produced by, the engine 10. The engine
is "turbocharged" in that the air handling system includes a
turbocharger 120 to provide the pressure necessary to aspirate the
engine 10. The turbocharger includes a compressor 122 and a turbine
121, which are coupled for mutual rotation. The air handling system
construction includes a charge air channel coupled to provide
charge air to the intake port or ports of the engine and an exhaust
channel coupled to transport exhaust gas from the exhaust port or
ports of the engine. The charge air channel includes an inlet for
fresh air, the compressor, a charge air passage coupled to the
compressor through which charge air is transported to intake ports
of the engine, and at least one charge air cooler (CAC) that cools
the charge air (or a mixture of gasses including charge air) before
delivery to the intake ports. Such a charge air cooler can comprise
an air-to-liquid and/or an air-to-air device, or another cooling
device. The exhaust channel includes the turbine, an exhaust
passage that transports exhaust gas from the exhaust ports of the
engine, and other components downstream of the turbine. In some
instances, the charge air channel may include a supercharger
110.
[0007] In greater detail, the air handling system 80 includes a
turbocharger 120 with a turbine 121 and a compressor 122. The
turbine 121 and compressor 122 rotate on a common shaft 123. The
turbocharger 120 extracts energy from exhaust gas that exits the
exhaust ports 54 and flows into an exhaust passage 124 directly
from the exhaust ports 54, or from an exhaust manifold 125 that
collects exhaust gasses output through the exhaust ports 54. In
this regard, the turbine 121 is rotated by exhaust gas passing
through it. This rotates the compressor 122, causing it to generate
charge air by compressing fresh intake air that flows into it from
a charge air channel inlet. The charge air generated by the
compressor 122 flows through a charge air passage 126 to a charge
air cooler 127. Presuming the addition of the supercharger 110,
cooled charge air is pumped by the supercharger 110 to the intake
ports. Air compressed by the supercharger 110 may be output through
a second charge air cooler 129 to an intake manifold 130. The
intake ports 56 receive charge air pumped by the supercharger 110,
through the intake manifold 130. Preferably, in multi-cylinder
opposed-piston engines, the intake manifold 130 is coupled to an
intake plenum that communicates with the intake port or ports 56 of
the engine 10.
[0008] The air handling system shown in FIG. 1 may be constructed
to reduce NOx produced by combustion by recirculating exhaust gas
through the ported cylinders of the engine. The recirculated
exhaust gas is mixed with charge air to lower peak combustion
temperatures, which lowers NOx emissions. This process is referred
to as exhaust gas recirculation ("EGR"); and the channel through
which the gas is recirculated is referred to as "an EGR loop". The
EGR construction shown utilizes exhaust gasses transported from the
exhaust ports, via an EGR loop external to the cylinder, into the
incoming stream of fresh intake air in the charge air
subsystem.
[0009] The EGR loop construction shown in FIG. 1 is a high pressure
configuration (also called "a short loop"). In this regard, a high
pressure EGR loop circulates exhaust gas obtained from a source
upstream of the intake of a turbine to a mixing point downstream of
the output of a compressor. In the EGR loop of FIG. 1, the exhaust
passage 131 and the EGR valve 138 shunt a portion of the exhaust
gas from the exhaust manifold 125 to be mixed with charge air
output by the compressor 122 into the charge air passage 126. This
loop subjects the recirculated exhaust gas to the cooling effects
of the two coolers 127 and 129. If less cooling is required, the
exhaust gas portion can be shunted around the cooler 127 to the
input of the supercharger 110; this alternative subjects the
exhaust gas portion to cooling by only the charge air cooler 129. A
dedicated EGR cooler that cools only exhaust gas may be
incorporated into the exhaust passage 131, in series with the valve
138, or in series with the output port of the valve 138 and the
input to the supercharger 110.
[0010] A low pressure EGR loop (also called a "long loop")
circulates exhaust gas obtained from a source downstream of the
turbine outlet to a mixing point upstream of the compressor intake.
Typically, a short loop EGR configuration is favored for fast
response, low complexity, and high durability, at the cost of
pumping loss, high concentration of exhaust products in the charge
air channel, and turbine lag. A long loop configuration is favored
for lower pumping loss, higher mass flow through the turbocharger,
and higher cooling capacity, at the cost of even slower turbine
response and greater complexity.
[0011] FIG. 2 shows the air handling system 80 of FIG. 1, with more
detail. In this regard, fresh air is provided to the inlet 122i of
the compressor 122 from an inlet 149 via an air filter 150. As the
compressor 122 is rotated by the turbine 121, compressed air flows
from the compressor's outlet 1220, through the charge air passage
126, and into the inlet 151 of the supercharger 110. Charge air
pumped by the supercharger 110 flows through the supercharger's
outlet 152 into the intake manifold 130. Pressurized charge air is
delivered from the intake manifold 130 to the intake ports of the
cylinders 50, which are supported in an engine block 160. The
second cooler 129 may be provided in the charge air channel, in
series between the output of the supercharger 110 and the intake
manifold 130.
[0012] Exhaust gas from the exhaust ports of the cylinders 50 flows
from the exhaust manifold 125 into the inlet 121i of the turbine
121, and from the turbine's outlet 1210 into the exhaust outlet
passage 128. A turbine bypass channel 143 including a wastegate
valve 144 runs in parallel with the turbine 121, between its inlet
121i and outlet 121o. The valve 144 is operated to control the
amount of exhaust gas flowing from the engine into the turbine 121.
Fully opening the valve 144 to bypass the turbine 121 allows
exhaust energy to be transported into the exhaust outlet passage
128 without operating the turbine 121 and compressor 122. In some
instances, the turbine 121 may comprise a variable-geometry turbine
(VGT) device, which would afford further control of gas flow (and
pressure) in the exhaust channel. In these aspects, the turbine 121
will have an effective opening size that may be varied in response
to changing speeds and loads of the engine. In some instances, one
or more after-treatment devices 162 are provided in the exhaust
channel, downstream of a backpressure valve 170. Exhaust is
recirculated through the EGR passage 131, under control of the EGR
valve 138. The EGR passage 131 is in fluid communication with the
charge air channel via an EGR mixer 163. In some instances,
although not necessarily, an EGR cooler ("EGR cooler 164") is
provided in the EGR passage 131, in series with the EGR valve 138
and the EGR mixer 163. In other instances, there may be no cooler
in the EGR passage 131.
[0013] With further reference to FIG. 2, the air handling system is
equipped for control of gas flow at separate control points in the
charge air and exhaust subsystems. In the charge air subsystem,
charge air flow and boost pressure are controlled by operation of a
recirculation channel 165 coupling the outlet 152 of the
supercharger to the supercharger's inlet 151. The recirculation
channel 165 includes a valve (the "recirculation valve") 166 that
governs the flow of charge air into, and thus the pressure in, the
intake manifold 130. A valve (the "backpressure valve") 170 may be
provided in the exhaust outlet channel to govern the flow of
exhaust out of, and thus the backpressure in, the exhaust
subsystem. In those instances when it is provided, the backpressure
valve 170 is positioned in the exhaust channel, between the output
1210 of the turbine 121 and the after-treatment devices 162.
[0014] Without a supercharger in the air handling system, a
turbocharged two-stroke cycle engine can perform poorly in response
to a demand for a sudden increase in engine speed. In this regard,
when the engine starts, or when it operates at low loads and/or low
speeds, the flow of exhaust may be insufficient to enable the
compressor to achieve the speed necessary to increase the flow of
charge air ("boost") to a level that is adequate to achieve the
requested engine speed. Further, the turbine operation may lag in
response to an increasing exhaust flow. In order to reduce the
transient response time imposed by the turbocharger, a
mechanically-driven supercharger may be added to the charge air
channel, downstream of the compressor outlet, so as to quickly
provide the boost needed for the demanded increase. However, the
supercharger and its associated coupling mechanism bring additional
weight and size to the engine and so constitute significant
impediments to downsizing.
[0015] Further, in the face of requirements for increased
efficiency of engine operation, it becomes ever more important to
quickly and precisely control gas flow (exhaust and charge air)
through the engine in response to changes in speed and load. The
control mechanization of the air handling system illustrated in
FIG. 2 is representative of the current state of air handling
control for turbocharged, opposed-piston engines. As can be seen
air handling control for such engines rests essentially on
valve-controlled adjustments to exhaust and charge air flow. Some
incremental improvement in air handling control may be achieved by
use of VGT devices and multi-speed mechanical drives for
superchargers. However, these are measures of limited effectiveness
and questionable utility.
SUMMARY
[0016] It is desirable to equip the air handling system of a
turbocharged opposed-piston engine for quick, yet smooth charge air
flow acceleration while starting the engine, and in response to
acceleration demands encountered during low speed and light load
conditions, without sacrificing the engine's efficiency and/or
power density. These and other goals and objectives may be realized
by use of an externally-assisted pumping element for the charge air
channel of the air handling system. Such an externally-assisted
pumping element may include an electrically-assisted compressor, an
electrically-assisted supercharger, or an electrically-assisted
turbocharger.
[0017] Desirably, external assistance of the very elements that
create charge air flow in a turbocharged, opposed-piston engine
provides the basis for finer control of charge air flow over a
broader range of effectiveness than is achievable with
currently-available air handling constructions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic diagram of a prior art turbocharged
opposed-piston engine with uniflow scavenging, and is appropriately
labeled "Prior Art".
[0019] FIG. 2 is a schematic diagram showing details of a prior art
air handling system for the opposed-piston engine of FIG. 1, and is
appropriately labeled "Prior Art".
[0020] FIGS. 3-8 are schematic diagrams showing respective
embodiments of an air handling system for a turbocharged
opposed-piston engine in which an electrically-assisted compressor
is provided in the charge air channel of the air handling system,
upstream of an inlet of the turbocharger compressor.
[0021] FIGS. 9-11 are schematic diagrams showing respective
embodiments of an air handling system for a turbocharged
opposed-piston engine in which an electrically-assisted compressor
is provided in the charge air channel of the air handling system,
downstream of an outlet of the turbocharger compressor.
[0022] FIGS. 12 and 13 are schematic diagrams showing respective
embodiments of an air handling system for a turbocharged
opposed-piston engine in which an electrically-assisted
supercharger is provided in the charge air channel of the air
handling system, downstream of an outlet of the turbocharger
compressor.
[0023] FIG. 14 is a schematic diagram showing an embodiment of an
air handling system for a turbocharged opposed-piston engine in
which an electrically-assisted supercharger is provided in the
charge air channel of the air handling system, in parallel with the
turbocharger compressor.
[0024] FIGS. 15-20 are schematic diagrams showing respective
embodiments of an air handling system for an opposed-piston engine
equipped with an electrically-assisted turbocharger.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] This disclosure is directed to aspects of air handling
system construction and operation for turbocharged opposed-piston
engines with the understanding that these aspects may be combined
with other opposed-piston engine systems and functions such as fuel
injection, cooling, lubrication, and so on. In this disclosure, an
air handling system for a turbocharged opposed-piston engine
according to FIG. 2 is modified according to by provision of one of
an electrically-assisted compressor, an electrically-assisted
supercharger, and an electrically-assisted turbocharger.
[0026] Electrically-Assisted Compressor:
[0027] An air handling system for a turbocharged opposed-piston
engine in which an electrically-assisted compressor provides boost
during engine startup and acceleration is illustrated by respective
embodiments shown in FIGS. 3-11. Since boost is provided by the
electrically-assisted compressor, these air handling system
embodiments do not include a supercharger.
[0028] In this disclosure, and with reference to FIGS. 3-11, "an
electrically-assisted compressor" means a dynamic compressor
device, such as a centrifugal compressor, driven by an associated
electric motor. The electrically-assisted compressor is provided as
a single compression unit, without an associated turbine.
Preferably, but not necessarily, the compressor 200 and its
associated electric motor 201 are provided as a single, integrated
device. Such devices are available, for example, from
Borg-Warner.RTM. under the trade name eBOOSTER.RTM..
Electrically-assisted compressors may be powered by regenerative
electrical storage (batteries, accumulators), or other means, under
control of an engine control unit. In the embodiments illustrated
in FIGS. 3-8, the electrically-assisted compressor 200 is disposed
in the charge air channel, in series with the compressor 122,
upstream of the compressor's inlet 122i; in FIGS. 9-12, the
electrically-assisted compressor 200 is disposed in the charge air
channel, in series with the compressor 122, downstream of the
compressor's outlet 122o.
[0029] With reference to FIG. 3, the air handling system includes a
long EGR loop 180 having an input 181 in the exhaust channel,
downstream of the turbine outlet 1210 and an outlet, via the EGR
mixer 163, in the charge air channel. With the long EGR loop
configuration, the exhaust aftertreatment devices 162 are
positioned downstream of the backpressure valve in order to take
advantage of continued exhaust flow through the EGR loop when the
backpressure valve 170 is closed. The electrically-assisted
compressor 200 is placed in the charge air channel, in series with
the compressor 122, upstream of the compressor inlet 122i and
downstream of the EGR mixer 163. In this embodiment, the
opposed-piston engine 10 is constructed with a cylinder block
having an open intake chamber in which all inlet ports are located
for receiving charge air, as is taught in commonly-owned U.S.
patent application Ser. No. 14/284,058, filed May 21, 2014, for
"Air Handling Constructions For Opposed-Piston Engines." The intake
chamber has charge air inlets on opposing sides of the engine
block. In order to serve the charge air inlets, the charge air
channel includes first and second branches 220 and 222 downstream
of the compressor 122. The first and second branches 220 and 222
have a common input 223 coupled to the outlet 122o of the
compressor 122, and each of the branches includes a respective
charge air cooler 224 and 226 placed between the common input 223
and a respective one of the charge air inlets. Preferably, the
turbine 121 comprises a VGT device.
[0030] With reference to FIG. 4, the air handling system has the
same construction as shown in FIG. 3, with the addition of a third
charge air cooler 230 placed in the charge air channel, between the
electrically-assisted compressor 200 and the compressor 122.
[0031] With reference to FIG. 5, the air handling system includes a
long EGR loop 180 as per FIG. 3. The electrically-assisted
compressor 200 is placed in the charge air channel, in series with
the compressor 122, upstream of the compressor inlet 122i and
downstream of the EGR mixer 163. In this embodiment, the
opposed-piston engine 10 is constructed with a cylinder block
having exhaust and intake chambers served by respective manifolds
125 and 130. Accordingly, the charge air channel includes a single
charge air passage 227 coupling the compressor outlet 122o with the
intake manifold 130. The charge air passage 227 includes a charge
air cooler 229 placed in the charge air channel between the output
122o of the compressor 122 and the intake manifold 130. Preferably,
the turbine 121 comprises a VGT device. The air handling system
illustrated in FIG. 6 has the same construction as shown in FIG. 5,
with the exception that the turbine 121 does not comprise a VGT
device.
[0032] With reference to FIGS. 7 and 8, the air handling systems
have the same construction as FIG. 5 except that neither includes
an EGR loop or aftertreatment devices; in each case, the turbine
121 may comprise a VGT or a fixed geometry device. Further, the air
handling system of FIG. 8 does not include a back pressure valve.
The air handling system illustrated in FIG. 7 includes a
valve-controlled bypass loop 232 having an inlet 233 in the charge
air channel, between the fresh air inlet 149 and an inlet 200i of
the electrically-assisted compressor 200, and an outlet 235 in the
charge air channel, between the outlet 200o of the
electrically-assisted compressor and the inlet 122i of the
compressor 122. The bypass loop 232 includes a bypass valve
236.
[0033] With reference to the air handling system illustrated in
FIG. 9, the electrically-assisted compressor 200 is placed in the
charge air channel, in series with the compressor 122, downstream
of the compressor outlet 122o and upstream of the intake ports of
the engine 10, specifically, upstream of the intake manifold 130. A
charge air cooler 240 is in the charge air channel, between the
outlet 1220 of the compressor 122 and the inlet 200i of the
electrically-assisted compressor 200. In FIG. 10, the air handling
system of FIG. 9 is modified by addition of a charge air cooler 242
in the charge air channel, between the outlet 2000 of the
electrically-assisted compressor 200 and the intake manifold 130.
In FIG. 11, the air handling system of FIG. 9 is modified by
addition of a valve-controlled backflow prevention passage 242 in
the charge air channel, downstream of the charge air cooler 240,
and having an inlet 243 in the charge air channel in common with
the inlet 200i of the electrically-assisted compressor 200 and an
outlet in the charge air channel, upstream of the intake manifold
130, in common with the outlet 200o of the electrically-assisted
compressor 200. The passage 240 includes a valve 243. The purpose
of the backflow prevention passage is to let the main turbocharger
operate without restriction when the electrically-assisted
compressor 200 is not needed.
[0034] Electrically-Assisted Supercharger:
[0035] An air handling system for a turbocharged opposed-piston
engine in which an electrically-assisted supercharger provides
boost during engine startup and acceleration is illustrated by
respective embodiments shown in FIGS. 12-14.
[0036] In this disclosure, and with reference to FIGS. 12-14, "an
electrically-assisted supercharger" means a positive-displacement
air-compression device, such as a Roots-type blower, driven by an
associated electric motor. The electrically-assisted supercharger
is not a dynamic gas flow compressor, such as a centrifugal
compressor, it is provided as a single compression unit, without an
associated turbine. Such devices are described, for example, in US
2015/0047617, published Feb. 19, 2015. Preferably, but not
necessarily, the supercharger 250 and its associated electric motor
251 are provided as a single, integrated device.
Electrically-assisted superchargers may be powered by regenerative
electrical storage (batteries, accumulators), or other means, under
control of an engine control unit. In the embodiments illustrated
in FIGS. 12 and 13, the electrically-assisted supercharger 250 is
disposed in the charge air channel, in series with the compressor
122, downstream of the compressor's outlet 122o. In the embodiment
illustrated in FIG. 14, the supercharger is disposed in the charge
air channel, in parallel with the compressor 322 b.
[0037] With reference to FIG. 12, the air handling system conforms
to the construction of the air handling system 80 of FIG. 2,
including the short EGR loop 131, with the exception that the
supercharger 110 is replaced with the electrically-assisted
supercharger 250 and its associated motor 251. Further, given the
degree of control over charge air flow afforded by the
electrically-assisted supercharger, the air handling system does
not include a supercharger recirculation loop.
[0038] With reference to the embodiment illustrated in FIG. 13, the
opposed-piston engine 10 is constructed with a cylinder block
having open exhaust and intake chambers. All exhaust ports of the
engine are located in the open exhaust chamber for expelling
exhaust gas and all inlet ports are located in the open intake
chamber for receiving charge air, as is taught in commonly-owned
U.S. patent application Ser. No. 14/284,058, filed May 21, 2014,
for "Air Handling Constructions For Opposed-Piston Engines." The
exhaust chamber has exhaust outlets on opposing sides of the
cylinder block and the intake chamber has charge air inlets on the
same opposing sides of the engine block.
[0039] One of the exhaust outlets is coupled to provide exhaust gas
to the turbine inlet 122i via the manifold 262; the other exhaust
outlet is coupled to the input of a short EGR loop 260 by an
exhaust manifold 264. The output of the short EGR loop 260 is
placed in the charge air channel via the mixer 265, downstream of
the compressor 122, between the compressor outlet 122o and the
charge air cooler 266. The charge air cooler 266 is placed in the
charge air channel, downstream of the mixer 265, between the mixer
265 and the inlet 250i of the electrically-assisted supercharger
250.
[0040] In order to serve the charge air inlets, the charge air
channel includes first and second branches 270 and 272 downstream
of the electrically-assisted supercharger 250. The first and second
branches 270 and 272 have a common input 273 coupled to the outlet
250o of the electrically-assisted supercharger 250, and each of the
branches includes a respective charge air cooler 274 and 276 placed
between the common input 273 and a respective one of the charge air
inlets. The turbine 121 may comprise a VGT device.
[0041] Although not shown in FIGS. 12 and 13, the air handling
system may be provided with a recirculation channel as per the
recirculation channel 165 seen in FIG. 2.
[0042] Referring to FIG. 14, the illustrated air handling system
has a much simpler construction than that shown and described in
FIG. 13. An electric motor 251 mechanically driving a supercharger
250 to provide an electrically assisted supercharger is located in
parallel with the turbo charger compressor 122. Furthermore, single
intake and exhaust manifolds 130 and 125 are located respectfully,
one either side of the cylinder block. With this configuration, a
regular turbocharger can be used avoiding the complexities of
mechanically, or electrically, driving the turbine to provide a
variable speed turbocharger. Optionally, a long EGR loop 180 may be
added before the supercharger 250, on the low-pressure outlet side
1210 of the turbine 121. Higher motor speeds are compatible with a
smaller supercharger running at higher-pressure ratios.
Furthermore, this configuration may be better with high efficiency
turbochargers because the supercharger can supply very low air flow
and can be switched off when turbocharger efficiencies are high
enough to provide a pressure differential from intake to exhaust. A
control valve 253 located between the compressor output and the
supercharger can balance airflow between the supercharger and
compressor outputs for precise balance of required pressure
differentials.
[0043] Electrically-Assisted Turbocharger:
[0044] In an air handling system for a turbocharged opposed-piston
engine, the turbocharger comprises an electrically-assisted
turbocharger as illustrated by respective embodiments shown in
FIGS. 15-19. In these embodiments, boost is provided by electrical
assistance to the compressor.
[0045] In this disclosure, and with reference to FIGS. 15-19, "an
electrically-assisted turbocharger" means a turbocharger 320
comprising a turbine 321 and compressor 322 coupled for mutual
rotation on a common shaft to which an associated electric motor
325 is also drivingly coupled. Preferably, but not necessarily, the
turbocharger 320 and its associated electric motor 325 are provided
as a single, integrated device. Such devices are described, for
example, in U.S. Pat. No. 6,739,845, issued May 25, 2004.
Electrically-assisted turbochargers may be powered by regenerative
electrical storage (batteries, accumulators), or other means, under
control of an engine control unit. In the embodiments illustrated
in FIGS. 14-19, the electrically-assisted turbocharger 320 is
placed with the turbine in the exhaust channel and the compressor
in the charge air channel.
[0046] With reference to FIGS. 15-17, the electrically-assisted
turbocharger 320 is situated in the air handling system in the same
manner as the non-assisted turbocharger 120 of FIG. 3. As per FIGS.
15-17, the air handling system includes a long EGR loop 180 having
an input 181 in the exhaust channel, downstream of the turbine
outlet 3210 and an outlet, via the EGR mixer 163, in the charge air
channel, upstream of the compressor inlet 322i.
[0047] In the embodiment illustrated in FIG. 15, the opposed-piston
engine 10 is constructed with a cylinder block having an open
intake chamber in which all inlet ports are located for receiving
charge air, as is taught in commonly-owned U.S. patent application
Ser. No. 14/284,058, filed May 21, 2014, for "Air Handling
Constructions For Opposed-Piston Engines." The intake chamber has
charge air inlets on opposing sides of the engine block. In order
to serve the charge air inlets, the charge air channel includes
first and second branches 220 and 222 downstream of the compressor
322. The first and second branches 220 and 222 have a common input
223 coupled to the outlet 322o of the compressor 322, and each of
the branches includes a respective charge air cooler 324 and 326
placed between the common input 223 and a respective one of the
charge air inlets. The turbine 321 may comprise fixed geometry
device or a VGT device.
[0048] In FIG. 16, the opposed-piston engine 10 is constructed with
a cylinder block having exhaust and intake chambers served by
respective manifolds 125 and 130. Accordingly, the charge air
channel includes a single charge air passage 227 coupling the
compressor outlet 322o with the intake manifold 130. The charge air
passage 227 includes a charge air cooler 229 placed in the charge
air channel between the output 322o of the compressor 322 and the
intake manifold 130. Preferably, the turbine 321 comprises a VGT
device. The air handling system illustrated in FIG. 17 has the same
construction as shown in FIG. 16, with the exception that the
turbine 321 does not comprise a VGT device. The air handling system
illustrated in FIG. 18 has the same construction as shown in FIG.
17, with the exception that the aftertreatment devices are removed
from the exhaust channel.
[0049] With reference to FIG. 19, the illustrated air handling
system has the same construction as shown in FIG. 18, with the
exception that the system contains no EGR loop. With reference to
FIG. 20, the illustrated air handling system has the same
construction as shown in FIG. 18, with the exception that the
system contains no EGR loop and no back pressure valve.
[0050] In some instances, when excessive power is generated by the
turbine 321, the motor 325 can act as a generator and provide
electric power for use or storage.
[0051] Although this disclosure describes particular embodiments
for air handling systems with externally-assisted boosting for
turbocharged opposed-piston engines, these embodiments are set
forth merely as examples of underlying principles of this
disclosure. Thus, the embodiments are not to be considered in any
limiting sense.
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