U.S. patent application number 12/816063 was filed with the patent office on 2011-12-15 for method and system for controlling engine performance.
Invention is credited to Kevin Paul Bailey, John Dowell, Lukas Johnson, Jonathan Nagurney, Roy Primus, Mark Stablein, Kendall Roger Swenson, Frederick Thwaites.
Application Number | 20110307127 12/816063 |
Document ID | / |
Family ID | 43585651 |
Filed Date | 2011-12-15 |
United States Patent
Application |
20110307127 |
Kind Code |
A1 |
Swenson; Kendall Roger ; et
al. |
December 15, 2011 |
METHOD AND SYSTEM FOR CONTROLLING ENGINE PERFORMANCE
Abstract
Methods and systems are provided for operating a vehicle
including an engine comprising a turbocharger including a
compressor and a turbine. The engine further includes a bypass path
configured to selectively route gas from downstream of the
compressor to upstream of the turbine. In one embodiment, the
method comprises selectively increasing gas flow to the engine by
adjusting gas flow through the bypass path from downstream of the
compressor to upstream of the turbine. In this manner, the
performance of the engine may be adjusted for various operating
conditions.
Inventors: |
Swenson; Kendall Roger;
(Erie, PA) ; Primus; Roy; (Niskayuna, NY) ;
Johnson; Lukas; (Erie, PA) ; Stablein; Mark;
(Erie, PA) ; Bailey; Kevin Paul; (Grove City,
PA) ; Dowell; John; (Grove City, PA) ;
Thwaites; Frederick; (Erie, PA) ; Nagurney;
Jonathan; (Erie, PA) |
Family ID: |
43585651 |
Appl. No.: |
12/816063 |
Filed: |
June 15, 2010 |
Current U.S.
Class: |
701/21 ;
60/605.1; 60/605.2; 60/611; 701/102 |
Current CPC
Class: |
B63H 21/21 20130101;
Y02T 10/12 20130101; F02B 37/16 20130101; Y02T 10/144 20130101 |
Class at
Publication: |
701/21 ;
60/605.1; 60/611; 60/605.2; 701/102 |
International
Class: |
F02D 41/00 20060101
F02D041/00; F02B 47/08 20060101 F02B047/08; F02M 25/07 20060101
F02M025/07; G06F 7/00 20060101 G06F007/00; F02B 33/40 20060101
F02B033/40; F02D 23/00 20060101 F02D023/00 |
Claims
1. A method of operating a vehicle comprising an engine including a
bypass path and a turbocharger, the turbocharger including a
compressor and a turbine, comprising, selectively increasing gas
flow to the engine by increasing gas flow through the bypass path
from downstream of the compressor to upstream of the turbine.
2. The method of claim 1, wherein gas flow through the bypass path
is increased when a notch setting is less than a threshold.
3. The method of claim 1, wherein gas flow through the bypass path
is decreased when a notch setting is greater than or equal to a
speed threshold.
4. The method of claim 1, wherein gas flow through the bypass path
is increased according to a difference between a notch setting and
a threshold.
5. The method of claim 1, wherein gas flow through the bypass path
is increased when a transient engine condition is detected, and
wherein the vehicle is a locomotive.
6. The method of claim 1, further comprising, determining an inlet
temperature of the turbine; and adjusting the bypass path according
to the determined inlet temperature.
7. The method of claim 6, wherein the bypass path is adjusted to
increase flow of heated gas through the bypass path from downstream
of the compressor to upstream of the turbine when the inlet
temperature is less than a threshold temperature.
8. The method of claim 7, wherein heating gas in communication with
the bypass path includes routing gas through a passage in thermal
contact with exhaust gasses.
9. The method of claim 6, wherein the bypass path is adjusted to
increase flow of cooled gas through the bypass path from downstream
of the compressor to upstream of the turbine when the inlet
temperature is greater than or equal to a threshold
temperature.
10. The method of claim 1, further comprising, calculating a
distance of the vehicle to each of a set of predefined geographic
features; determining if the vehicle is within a threshold range of
any of the predefined geographic features; and adjusting the bypass
path if the vehicle is within the threshold range of any of the
predefined geographic features.
11. The method of claim 10, wherein calculating a distance of the
vehicle to each of a set of predefined geographic features includes
determining geographic coordinates of the vehicle using a Global
Positioning System signal.
12. A method of operating a vehicle comprising an engine including
a bypass path and a turbocharger including a compressor and a
turbine, the bypass path configured to selectively route gas from
downstream of the compressor to upstream of the turbine,
comprising, adjusting flow through the bypass path from downstream
of the compressor to upstream of the turbine based on whether the
vehicle is operating in or within a threshold range of a
tunnel.
13. The method of claim 12, wherein adjusting flow through the
bypass path from downstream of the compressor to upstream of the
turbine includes increasing flow through the bypass path when the
vehicle is within a threshold range of an entrance of the
tunnel.
14. The method of claim 12, wherein adjusting flow through the
bypass path from downstream of the compressor to upstream of the
turbine includes decreasing flow through the bypass path when the
vehicle is in the tunnel.
15. The method of claim 12, wherein the engine further comprises an
exhaust gas recirculation system, further comprising, decreasing
flow of gas from the exhaust gas recirculation system when the
vehicle is in the tunnel.
16. The method of claim 15, further comprising, increasing flow of
gas from the exhaust gas recirculation system when the vehicle
exits the tunnel.
17. The method of claim 12, wherein gas from downstream of the
compressor is cooled.
18. A vehicle system, comprising: an engine including a bypass path
and a turbocharger including a turbine and a compressor, the bypass
path configured to selectively route gas from downstream of the
compressor to upstream of the turbine; and a control system having
computer readable storage medium with code therein, the code
including instructions for, calculating a distance of the vehicle
system to each of a set of predefined geographic features;
determining if the vehicle system is within a threshold range of
any of the predefined geographic features; and adjusting the bypass
path if the vehicle system is within the threshold range of any of
the predefined geographic features.
19. The vehicle system of claim 18, wherein the set of predefined
geographic features includes a tunnel entrance.
20. The vehicle system of claim 18, further comprising a Global
Positioning System receiver sending a signal to the control system,
and wherein the code further includes instructions for, determining
geographic coordinates of the vehicle system for calculating the
distance of the vehicle system to each of the set of predefined
geographic features; and increasing flow of gas through the bypass
path when the vehicle system is within the threshold range of one
of the predefined geographic features.
21. The vehicle system of claim 18, wherein the engine includes a
combustion portion having at least one cylinder where a gas/fuel
mixture is combusted for driving a mechanical output shaft of the
engine, and wherein gas that is selectively routed through the
bypass path bypasses the combustion portion of the engine.
22. A method of operating a marine vehicle comprising an engine
including a turbocharger including a compressor and a turbine,
comprising, adjusting a bypass path from downstream of the
compressor to upstream of the turbine when an engine acceleration
exceeds an acceleration threshold; and adjusting the bypass path
from downstream of the compressor to upstream of the turbine when
an engine deceleration exceeds a deceleration threshold.
23. The method of claim 22, wherein the bypass path is adjusted
according to an engine speed and a propeller load when the engine
acceleration exceeds the acceleration threshold.
24. The method of claim 23, wherein gas flow through the bypass
path is heated when the engine acceleration exceeds the
acceleration threshold.
25. The method of claim 22, wherein the bypass path is adjusted
according to an intake manifold pressure, an engine speed, and a
propeller load when the engine deceleration exceeds the
deceleration threshold.
26. The method of claim 22, wherein the deceleration threshold and
the acceleration threshold vary according to engine speed.
27. A marine vehicle system, comprising: an engine including a
bypass path and a turbocharger including a turbine and a
compressor, the bypass path configured to selectively route gas
from downstream of the compressor to upstream of the turbine; a
propeller; a coupling device connected to the engine and configured
to selectively engage and disengage with the propeller; a control
system having computer readable storage medium with code therein,
the code including instructions for, selectively engaging the
propeller; selectively disengaging the propeller; adjusting a
bypass path from downstream of the compressor to upstream of the
turbine when an engine acceleration exceeds an acceleration
threshold and the propeller is engaged; and adjusting the bypass
path from downstream of the compressor to upstream of the turbine
when an engine deceleration exceeds a deceleration threshold.
28. The marine vehicle system of claim 27, wherein the bypass path
is adjusted according to an engine speed when the engine
acceleration exceeds the acceleration threshold and the propeller
is engaged.
29. The marine vehicle system of claim 27, wherein gas flow through
the bypass path is heated when the engine acceleration exceeds the
acceleration threshold and the propeller is engaged.
30. The marine vehicle system of claim 27, wherein the bypass path
is adjusted according to an intake manifold pressure and an engine
speed when the engine deceleration exceeds the deceleration
threshold.
Description
FIELD
[0001] The subject matter disclosed herein relates to a method and
system for controlling engine performance in a vehicle, such as a
locomotive or a mining truck.
BACKGROUND
[0002] An off-highway vehicle, such as a locomotive, a mining
truck, or a marine vehicle, may include an engine having a
turbocharger that is designed to have greater efficiency at the
most frequent engine operating conditions. However, such designs
may result in lower efficiency at a less common engine operating
condition. For example, a vehicle may have a turbocharger with
greater efficiency at peak output power than at lower power output.
Specifically, the turbocharger compressor and/or turbine may be
shaped to optimize flow at higher speeds and pressure ratios,
thereby resulting in improved engine efficiency where the engine
operates most.
[0003] The inventors herein have recognized that even though such
turbocharger designs may optimize performance overall, engine
performance may be degraded at some operating regions, such as mid
speed and mid load regions.
BRIEF DESCRIPTION OF THE INVENTION
[0004] Methods and systems are provided for operating a vehicle
including an engine and a turbocharger, the turbocharger including
a compressor and a turbine. The engine further includes a bypass
path configured to selectively route gas from downstream of the
compressor to upstream of the turbine. In one embodiment, the
method comprises selectively increasing gas flow to the engine by
adjusting gas flow through the bypass path from downstream of the
compressor to upstream of the turbine. In this manner, the
performance of the engine may be adjusted for various operating
conditions.
[0005] Thus, the performance of the turbocharger may be increased
in less efficient operating regions by selectively bypassing gas
from downstream of the compressor to upstream of the turbine. For
example, during some engine operating conditions, such as when the
engine is generating low power output, increased gas flow may be
routed through the bypass path to provide additional energy to the
turbine and the turbocharger may operate in a more efficient
operating range, increasing the airflow to the engine, and thus the
air-fuel ratio and the engine efficiency. During other engine
operating conditions, such as when the engine is generating peak
power output, the bypass path may be closed.
[0006] This brief description is provided to introduce a selection
of concepts in a simplified form that are further described herein.
This brief description is not intended to identify key features or
essential features of the claimed subject matter, nor is it
intended to be used to limit the scope of the claimed subject
matter. Furthermore, the claimed subject matter is not limited to
implementations that solve any or all disadvantages noted in any
part of this disclosure. Also, the inventor herein has recognized
any identified issues and corresponding solutions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The present invention will be better understood from reading
the following description of non-limiting embodiments, with
reference to the attached drawings, wherein below:
[0008] FIG. 1 shows an example embodiment of a diesel-electric
locomotive including a turbocharged engine.
[0009] FIG. 2 shows an example embodiment of a turbocharged engine
including a compressor, a turbine, and one or more bypass paths for
compressed gas to be routed upstream of the turbine.
[0010] FIG. 3 shows prophetic data of a turbocharger compressor
map.
[0011] FIG. 4 shows a high level flow chart of an embodiment of a
method of adjusting bypass paths between the turbocharger
compressor outlet and the turbocharger turbine inlet.
[0012] FIG. 5 shows a high level flow chart of an embodiment of a
method of adjusting bypass paths between the turbocharger
compressor outlet and the turbocharger turbine inlet for an example
operating condition, such as when a vehicle is near or in a
tunnel.
[0013] FIG. 6 shows an example embodiment of a diesel-electric
marine vehicle including a turbocharged engine.
[0014] FIG. 7 shows a high-level flow chart of an embodiment of a
method of adjusting bypass paths between the turbocharger
compressor outlet and the turbocharger turbine inlet for a marine
vehicle.
DETAILED DESCRIPTION
[0015] Vehicles, such as marine vehicles, mining trucks, or the
example embodiment of a locomotive in FIG. 1, may include an engine
having a turbocharger that is more efficient when the engine is
producing peak power output in steady-state. However, it may be
desirable to increase the efficiency and/or decrease the emissions
of the engine during non-peak power output conditions and during
transient conditions. In FIG. 2, an example embodiment of a
turbocharged engine includes a compressor, a turbine, and one or
more bypass paths for compressed gas to be routed upstream of the
turbine. By controlling the bypass paths when the engine is
operating at non-peak or transient conditions, the operating point
of the turbocharger may be moved from a less efficient operating
point (in terms of flow for a given boost pressure) on the
turbocharger compressor map to a more efficient operating point on
the turbocharger compressor map, as shown by the prophetic data of
the turbocharger compressor map of FIG. 3. FIG. 4 shows a high
level flow chart of an embodiment of a method of adjusting the
bypass paths between the turbocharger compressor outlet and the
turbocharger turbine inlet. In addition, there may be distinct
engine operating conditions when adjusting bypass paths between the
turbocharger compressor outlet and the turbocharger turbine inlet
may be tailored to the distinct engine and/or vehicle operating
conditions. One such operating condition may be when a vehicle is
near or in a tunnel, as shown by the high level flow chart of an
embodiment of a method in FIG. 5. In this manner, by adjusting
bypass paths between the turbocharger compressor outlet and the
turbocharger turbine inlet, the efficiency of the engine may be
increased and/or the emissions of the engine may be decreased when
the engine is operating at non-peak or transient conditions. A
marine vehicle, such as the marine vehicle of FIG. 6, may have
additional and/or alternative operational characteristics compared
to a locomotive and thus, bypass paths of the engine may be
adjusted in a suitable manner for a marine vehicle. FIG. 7
illustrates one example of how bypass paths of an engine of a
marine vehicle may be adjusted when accelerating or decelerating
the marine vehicle.
[0016] FIG. 1 is a block diagram of an example vehicle or vehicle
system, herein depicted as locomotive 100, configured to run on
track 104. In one example, locomotive 100 may be a diesel electric
vehicle operating with a diesel engine 106 located within a main
engine housing 102. However, in alternate embodiments, alternate
engine configurations may be employed, such as a gasoline,
biodiesel, or natural gas engine, for example.
[0017] Locomotive operating crew and electronic components involved
in locomotive systems control and management, for example
controller 110, may be housed within a locomotive cab 108. In one
example, controller 110 may include a computer control system. The
locomotive control system may further comprise computer readable
storage media including code for enabling an on-board monitoring of
locomotive operation. Controller 110, overseeing locomotive systems
control and management, may be configured to receive signals from a
variety of sensors, as further elaborated herein, in order to
estimate locomotive operating parameters. For example, controller
110 may estimate geographic coordinates of locomotive 100 using
signals from a Global Positioning System (GPS) receiver 140.
Controller 110 may be further linked to display 112, such as a
diagnostic interface display, providing a user interface to the
locomotive operating crew. Controller 110 may control the engine
106, in response to operator input, by sending a command to various
engine control hardware components such as inverters 118,
alternator 116, relays, fuel injectors, fuel pumps (not shown),
etc. For example, the operator may select a power output for the
locomotive by operating a throttle control 114. Locomotives may
have a finite number of throttle settings, or notches. For example,
a locomotive may have an idle position and eight power positions,
with notch eight indicating the highest power output and notch 1
indicating the lowest power output above idle. Operating with a
discrete number of throttle positions may differ from other
vehicles, such as trucks, which may have a variable throttle that
may be positioned anywhere in the continuum between idle and full
throttle. The operator may provide other inputs to controller 110,
such as notification that locomotive 100 is approaching a tunnel or
that locomotive 100 is in a tunnel.
[0018] Engine 106 may be started with an engine starting system. In
one example, a generator start may be performed wherein the
electrical energy produced by a generator or alternator 116 may be
used to start engine 106. Alternatively, the engine starting system
may comprise a motor, such as an electric starter motor, or a
compressed air motor, for example. It will also be appreciated that
the engine may be started using energy in a battery system, or
other appropriate energy sources.
[0019] The diesel engine 106 generates a torque that is transmitted
to an alternator 116 along a drive shaft (not shown). The generated
torque is used by alternator 116 to generate electricity for
subsequent propagation of the vehicle. The electrical power may be
transmitted along an electrical bus 117 to a variety of downstream
electrical components. Based on the nature of the generated
electrical output, the electrical bus may be a direct current (DC)
bus (as depicted) or an alternating current (AC) bus.
[0020] Alternator 116 may be connected in series to one, or more,
rectifiers (not shown) that convert the alternator's electrical
output to DC electrical power prior to transmission along the DC
bus 117. Based on the configuration of a downstream electrical
component receiving power from the DC bus, one or more inverters
118 may be configured to invert the electrical power from the
electrical bus prior to supplying electrical power to the
downstream component. In one embodiment of locomotive 100, a single
inverter 118 may supply AC electrical power from a DC electrical
bus to a plurality of components. In an alternate embodiment, each
of a plurality of distinct inverters may supply electrical power to
a distinct component.
[0021] A traction motor 120, mounted on a truck 122 below the main
engine housing 102, may receive electrical power from alternator
116 through the DC bus 117 to provide traction power to propel the
locomotive. As described herein, traction motor 120 may be an AC
motor. Accordingly, an inverter paired with the fraction motor may
convert the DC input to an appropriate AC input, such as a
three-phase AC input, for subsequent use by the traction motor. In
alternate embodiments, traction motor 120 may be a DC motor
directly employing the output of the alternator 116 after
rectification and transmission along the DC bus 117. One example
locomotive configuration includes one inverter/traction motor pair
per wheel-axle 124. As depicted herein, six pairs of
inverter/traction motors are shown for each of six pairs of
wheel-axle of the locomotive. Traction motor 120 may also be
configured to act as a generator providing dynamic braking to brake
locomotive 100. In particular, during dynamic braking, the traction
motor may provide torque in a direction that is opposite from the
rolling direction, thereby generating electricity that is
dissipated as heat by a grid of resistors 126 connected to the
electrical bus. In one example, the grid includes stacks of
resistive elements connected in series directly to the electrical
bus. The stacks of resistive elements may be positioned proximate
to the ceiling of main engine housing 102 in order to facilitate
air cooling and heat dissipation from the grid.
[0022] Air brakes (not shown) making use of compressed air may be
used by locomotive 100 as part of a vehicle braking system. The
compressed air may be generated from intake air by compressor 128.
A multitude of motor driven airflow devices may be operated for
temperature control of locomotive components. The airflow devices
may include, but are not limited to, blowers, radiators, and fans.
A variety of blowers 130 may be provided for the forced-air cooling
of various electrical components. For example, a traction motor
blower to cool traction motor 120 during periods of heavy work.
Engine temperature is maintained in part by a radiator 132. A
cooling system comprising a water-based coolant may optionally be
used in conjunction with the radiator 132 to provide additional
cooling of the engine.
[0023] An on-board electrical energy storage device, represented by
battery 134 in this example, may also be linked to DC bus 117. A
DC-DC converter (not shown) may be configured between DC bus 117
and battery 134 to allow the high voltage of the DC bus (for
example in the range of 1000V) to be stepped down appropriately for
use by the battery (for example in the range of 12-75V). In the
case of a hybrid locomotive, the on-board electrical energy storage
device may be in the form of high voltage batteries, such that the
placement of an intermediate DC-DC converter may not be
necessitated. The battery may be charged by running engine 106. The
electrical energy stored in the battery may be used during a
stand-by mode of engine operation, or when the engine is shut down,
to operate various electronic components such as lights, on-board
monitoring systems, microprocessors, displays, climate controls,
and the like. Battery 134 may also be used to provide an initial
charge to start-up engine 106 from a shut-down condition. In
alternate embodiments, the electrical energy storage device may be
a super-capacitor, for example.
[0024] Locomotive 100 may be coupled to a vehicle, such as another
locomotive or a railroad car, with a coupling device, such as
coupler 150. Locomotive 100 may include one or more couplers to
couple with one or more vehicles in a series of vehicles. In one
example, a first locomotive may be connected to a second locomotive
with coupler 150. A controller in the first locomotive, such as
controller 110, may be configured to receive and transmit
information to a controller in the second locomotive. The
information may include the position or order of a series of
locomotives, for example. As non-limiting examples, the information
may be transmitted with a wireless network or an electrical cable
connecting each locomotive. In this manner, a locomotive may
communicate information such as engine and/or vehicle operating
conditions to one or more other locomotives.
[0025] FIG. 2 illustrates an example embodiment of engine 106
comprising bypass path 230 and a turbocharger 220 including a
compressor 222, a turbine 226, and a driveshaft 224 connecting
compressor 222 to turbine 226. Compressor 222 receives gas, such as
air at atmospheric pressure, through inlet 210 and outputs
compressed gas at boost pressure into air passage 212. In an
alternative embodiment configured for port fuel injection, gas
entering inlet 210 may include atomized liquid fuel or gaseous
fuel, such as compressed natural gas (CNG), for example. In yet
another alternative embodiment, gas entering inlet 210 may include
exhaust gasses, such as when low pressure exhaust gas recirculation
is included. In yet another alternative embodiment, gas entering
inlet 210 may be compressed gas from an earlier stage compressor in
a multi-stage turbocharger. Compressed gas may be cooled by
intercooler 214 as the gas travels from passage 212 through
intercooler 214 to passage 216. Compressed gas may enter an intake
manifold 218 from passage 216. The pressure and temperature of gas
in intake manifold 218 may be measured with a pressure sensor 206
and a temperature sensor 207, respectively. Properties of the
intake gas may be measured with one or more of a pressure sensor
203, a temperature sensor 204, and a mass airflow sensor 205 to
measure the pressure, temperature, and mass airflow, respectively,
of the intake gas.
[0026] Engine 106 may receive control parameters from a control
system including controller 110. Controller 110 may include a
processor 201 for executing instructions that are stored in a
computer readable storage medium, such as memory 202. The
instructions may include routines for controlling bypass path 230,
for example. Controller 110 may receive signals from engine sensors
such as sensors 203-209 and 245 to determine engine operating
conditions. Controller 110 may transmit signals to valves 232, 234,
and 262 to control engine 106, for example. Controller 110 may
execute code to determine an engine operating mode and the engine
operating mode may be stored in the computer readable storage
medium.
[0027] The example embodiment of engine 106 comprises a first
cylinder bank 240 including one or more cylinders 242 and a second
cylinder bank 250 including one or more cylinders 252. Each
cylinder of engine 106 includes a combustion chamber where gasses
may be received from intake manifold 218 and burned with fuel that
may be injected with a fuel injector (not shown) controlled by
controller 110. Exhaust gasses from each cylinder of the second
cylinder bank 250 are received by a second exhaust manifold 254 and
may be recirculated to the intake manifold 218 through an exhaust
gas recirculation (EGR) system 260. EGR system 260 is depicted as a
high pressure EGR system, but in an alternative embodiment, a low
pressure EGR system may be used. The example embodiment of EGR
system 260 includes valve 262 and intercooler 264 for cooling
exhaust gasses before reintroducing them into intake manifold 218.
As a non-limiting example, valve 262 may be a flutter valve. In an
alternative embodiment, EGR system 260 may include a compressor for
compressing exhaust gas to the pressure in intake manifold 218.
[0028] In a non-limiting example, sensor 245 may be a hall effect
sensor for measuring the speed of engine 106. Exhaust gasses from
first cylinder bank 240 are received by a first exhaust manifold
244. Exhaust gasses may flow from first exhaust manifold 244
through passage 246, turbine 226, and passage 248. An emission
control device (not shown) may be configured to treat exhaust
gasses downstream of passage 248. In an alternative embodiment, a
wastegate may be included to route exhaust gasses from passage 246
to passage 248, bypassing turbine 226. In another alternative
embodiment, gas flowing from passage 248 may flow through an
earlier stage turbine in a multi-stage turbocharger.
[0029] In the example embodiment, turbocharger 220 is powered by
energy from the gasses flowing from passage 246 through turbine 226
to passage 248. Specifically, the flowing gasses impart rotational
energy to blades of turbine 226, turning driveshaft 224 and
powering compressor 222. In this manner, the flowing gasses provide
energy to compressor 222 to create a pressure differential between
inlet 210 and passage 212. Speed sensor 208 may measure the
rotational speed of turbocharger 220. In a non-limiting example,
speed sensor 208 may be a hall effect sensor.
[0030] In the example embodiment of engine 106, turbocharger 220
may be more efficient when engine 106 is producing peak power
output in steady-state and gas flow through turbine 226 may be
greater than at other operating conditions. However, it may be
desirable to increase the efficiency and/or decrease the emissions
of the engine during non-peak power output conditions and during
transient conditions. For example, turbocharger 220 may operate at
low efficiency when mass air flow through the compressor is low,
and increasing the mass air flow may increase the efficiency of
turbocharger 220. Bypass path 230 may include one or more paths for
gas at boost pressure to flow to passage 246 upstream of turbine
226. The additional flow of gas through turbine 226 may increase
the speed of driveshaft 224 and enable more gas to flow through
compressor 222. The additional flow of gas through compressor 222
may move the operating point of turbocharger 220 to a more
efficient point enabling more boost pressure and more gas to flow
to engine 106, thus increasing the efficiency of engine 106.
[0031] As a non-limiting example, bypass path 230 includes valves
232 and 234 for selectively routing gas from passage 212 (e.g.,
downstream of the compressor 222 and upstream of the intercooler
214) to passage 246 (e.g., upstream of the turbine 226) and for
routing gas from passage 216 (e.g., downstream of the compressor
222 and downstream of the intercooler 214) to passage 246. The gas
may be heated before reaching passage 246 with heater 236. In a
non-limiting example, heater 236 may include one or more passages
routed in thermal contact with exhaust passage 248 so that the heat
from exhaust gasses may be used to heat gas in bypass path 230.
Valve 232 may comprise one or more variable area valves for routing
gas from passage 212 and/or passage 216 to valve 234. In one
embodiment, valve 232 may be a three port valve. Controller 110 may
adjust valve 232 to control the degree of opening of each port of
valve 232. Valve 234 may comprise one or more variable area valves
for routing gas from valve 232 to passage 246. In one
configuration, gas may be routed through valve 234 to passage 246
through heater 236. In one embodiment, valve 234 may be a three
port valve. Controller 110 may adjust valve 234 to control the
degree of opening of each port of valve 234. Non-limiting examples
of valves 232 and valve 234 include a fixed orifice, a pneumatic
wastegate valve, and an electromechanical valve. Each valve may be
controlled by a digital, analog, or pulse-width modulated signal,
for example.
[0032] Gas bypassed from downstream of compressor 222 may be heated
or cooled on the way to passage 246 upstream of turbine 226.
Heating or cooling may be performed selectively based on engine
operating conditions. In one embodiment, bypassed gas from passage
212 in communication with bypass path 230 may be heated by heater
236 on the way to passage 246. The additional thermal energy from
the heated gas may provide additional energy to the turbine and
increase airflow through turbocharger 220. In another example,
cooled gas from intercooler 214 may be routed through bypass path
230 to passage 246. The cooled gas may reduce the temperature of
gas flowing through turbine 226 which may be desirable when the
turbine is designed to operate below a temperature threshold and
the current temperature conditions are at or near the threshold. In
yet another example, bypassed gas from passage 212 may be routed
through bypass path 230 and a fraction of the gas is heated by
heater 236 and the other fraction of the gas routed to passage 246
without heating. In this manner, thermal energy may be added to gas
entering turbine 226 while keeping the temperature of the gas below
the temperature threshold.
[0033] The temperature of gas in passage 246 upstream of turbine
226 may be measured by temperature sensor 209 and transmitted to
controller 110. In an alternative embodiment, the temperature of
gas in passage 246 may be estimated from other engine operating
conditions.
[0034] As illustrated in FIG. 2, there are various paths for the
bypassed gas to take from downstream of compressor 222 to upstream
of turbine 226. Bypass path 230 may be configured in different ways
to decrease the cost or complexity of routing or to increase the
capabilities of bypass path 230, for example. In one embodiment,
bypass path 230 is configured so gas from the outlet of the
compressor 222 may be routed from upstream of intercooler 214 to
the turbine inlet through a valve. In this configuration of bypass
path 230, routing complexity may be decreased compared to other
embodiments of bypass path 230. In another embodiment, bypass path
230 may be configured so gas from the outlet of intercooler 214 may
be routed from upstream of intake manifold 218 to the turbine inlet
through a valve. Bypassed gas may be cooled in this configuration
of bypass path 230. In yet another embodiment, bypass path 230 may
be configured so gas from the outlet of compressor 222 may be
routed from upstream of intercooler 214 to the turbine inlet
through a valve and heater 236. Bypassed gas may be heated in this
configuration of bypass path 230. In yet another embodiment, bypass
path 230 may be configured so gas from intake manifold 218 may be
routed to exhaust manifold 244 through a valve. Bypassed gas may be
cooled in this configuration of bypass path 230. In yet another
embodiment, bypass path 230 may be configured so gas from the
outlet of the compressor 222 may be routed from upstream of
intercooler 214 to the first port of a three-port valve, gas from
the outlet of intercooler 214 may be routed from upstream of intake
manifold 218 to a second port of the three-port valve, and a third
port of the three-port valve may be routed to turbine inlet. In
this configuration of bypass path 230, gas from compressor 222 and
cooled gas from intercooler 214 may be blended in the three-port
valve to tailor a turbocharger exhaust stream temperature to an
aftertreatment device. In yet another embodiment, turbocharger 220
may be the final stage of a multi-stage turbocharger and bypass
path 230 may be configured to route gas from downstream of
compressor 222 to upstream of a turbine in an earlier stage of the
multi-stage turbocharger.
[0035] The prophetic data of FIG. 3 illustrates an example of
operation of turbocharger 220 and bypass path 230 during non-peak
power output operating conditions, when the turbocharger may be
less efficient than during peak power output operating conditions.
Compressor map 300 includes a vertical axis for a pressure ratio of
boost pressure divided by compressor inlet pressure and a
horizontal axis for the mass flow of gas through the compressor.
Surge line 310 indicates the conditions when compressor 222 is in
surge. Surge occurs during low mass flow, when gas flowing through
the compressor stalls and may reverse. The reversal of gas flow may
cause the engine to lose power. Extending from surge line 310 are
lines of constant turbocharger speed, such as turbocharger
speedline 320. The turbocharger is more efficient when the
operating conditions fall within high efficiency island 330. When
the mass flow or the pressure ratio falls outside of high
efficiency island 330, the turbocharger will operate less
efficiently.
[0036] For example, locomotive 100 may be operating with a low
notch throttle position and a mass flow of gas through compressor
222 and a pressure ratio of passage 212 pressure divided by inlet
210 pressure correspond to operating condition 340. Turbocharger
220 is less efficient at operating condition 340 than in high
efficiency island 330. However, if the speed of turbocharger 220
can be increased to an area of higher turbocharger efficiency, the
mass flow of gas through compressor 222 may be increased and the
boost pressure may be increased. The speed of turbocharger 220 may
be increased by adjusting bypass path 230 so high pressure air is
routed upstream of turbine 226. Adjusting bypass path 230 to heat
the high pressure air with heater 236 may further increase the
speed of turbocharger 220. For example, adjusting bypass path 230
may increase the speed of turbocharger 220 so that the turbocharger
operating condition is moved from operating condition 340 to
operating condition 350 in high efficiency island 330.
[0037] As a result, for the given engine operating condition,
increased air charge may be provided to the cylinder at the same
power output, thus enabling an increased air-fuel ratio and reduced
emissions.
[0038] FIG. 4 shows an example embodiment of a method 400 of
selectively increasing gas flow to engine 106 by adjusting (e.g.,
increasing) gas flow through bypass path 230 to increase the speed
of turbocharger 220 so that the turbocharger operating condition
may be moved from a less efficient operating condition to a more
efficient operating condition. Bypass path 230 may also be used in
conjunction with other engine components, such as intercooler 214
and heater 236, to control other aspects of engine 106. In one
example, bypass path 230 may be used to increase the power output
from engine 106 when cooled gas is routed through bypass path 230
and power output from engine 106 is limited by the temperature of
gas entering the inlet of turbine 226. In another example, bypass
path 230 may be used to increase the efficiency of turbocharger 220
by routing heated gas through bypass path 230 to upstream of
turbine 226. In yet another example, bypass path 230 may be used to
adjust engine 106 for distinct engine operating conditions, such as
approaching or entering a geographic feature, such as a tunnel.
[0039] Code for executing routine 400 may be encoded as
instructions stored on a computer readable storage medium, such as
memory 202, and executed by processor 201 of controller 110.
[0040] Continuing with routine 400, at 410, the operating
conditions of the vehicle and engine 106 may be estimated and/or
measured. For example, engine speed and turbine inlet temperature
may be measured with sensors 245 and 209, respectively. The
position of throttle control 114 may be determined. Transient
engine conditions may be detected, such as a change in throttle
position or a change in load, such as when accelerating or climbing
a hill. Smoke emissions may be measured with a sensor or estimated
based on engine operating conditions. Geographic coordinates of the
vehicle may be estimated or calculated. For example, a GPS signal
from GPS receiver 140 may be used to calculate the geographic
coordinates of the vehicle. Geographic features in the path of the
vehicle, such as locomotive 100, may be signaled by an operator or
calculated. For example, geographic coordinates of a set of
predefined geographic features may be stored in a table. A distance
between the vehicle and the set of predefined geographic features
may be calculated so that the nearest geographic feature and its
distance may be determined. Non-limiting examples of geographic
features that may be stored in the set of predefined geographic
features include a tunnel entrance, a steep grade, and a city
boundary.
[0041] Distinct engine operating modes may be set based on operator
input or the operating conditions of engine 106. In one example, a
tunnel operating mode may be set when an approaching tunnel is
detected, or when the vehicle is within the tunnel. In another
example, a boost limiting mode may be set when gas entering inlet
210 is below a threshold temperature and above a threshold
pressure, such as when the vehicle is operating at low altitude on
a cold day. In yet another example, a hotel power mode may be set
when passenger locomotive is parked at a station. In yet another
example, an emission control mode may be set when emissions of
engine 106 are to be reduced. In yet another example, a hill
climbing mode may be set when an approaching steep grade is
detected. From 410, the routine continues at 420.
[0042] At 420, the turbine inlet temperature measured or estimated
at 410 is compared to a temperature threshold. The temperature
threshold is set at a highest desirable temperature of gas entering
turbine 226. For example, the temperature threshold may be set to
prevent damage of turbine 226 due to overheating. The temperature
threshold may be a constant value or the temperature threshold may
change during operation of engine 106. For example, the temperature
threshold may be reduced if turbine inlet temperatures have been
close to the temperature threshold for extended periods of time.
Likewise, the temperature threshold may be raised if the turbine
inlet pressures have been below the temperature threshold for
extended periods of time. If the turbine inlet temperature is
greater than the temperature threshold, the routine proceeds to
422. If the turbine inlet temperature is less than or equal to the
temperature threshold, the routine proceeds to 424.
[0043] At 422, bypass path 230 may be adjusted to use cool air from
passage 216 and to bypass heater 236. For example, a first port of
valve 232 in communication with passage 212 may be closed, a second
port of valve 232 in communication with passage 216 may be opened,
and a first port of valve 234 in communication with heater 236 may
be closed. In an alternative embodiment, bypass path 230 may be
adjusted to use air from passage 212 and to bypass heater 236. In
another alternative embodiment, bypass path 230 may be adjusted to
use a first fraction of air from passage 212 and a second fraction
of air from passage 216 so that the temperature of air flowing
through bypass path 230 may be controlled to a temperature between
the temperatures in passages 212 and 216. From 422, the routine
proceeds to 430.
[0044] At 424, bypass path 230 may be adjusted to use heated air
from passage 212 and to use heater 236. For example, a first port
of valve 232 in communication with passage 212 may be opened, a
second port of valve 232 in communication with passage 216 may be
closed, and a first port of valve 234 in communication with heater
236 may be opened. From 422, the routine proceeds to 430.
[0045] At 430, the routine may determine if one or more distinct
engine operating modes are detected. Non-limiting examples of
distinct engine operating modes include tunnel operating mode, hill
climbing mode, boost limiting mode, hotel power mode, and emission
control mode. In the example embodiment, when more than one
distinct engine operating mode is detected, a priority encoder or
other selection algorithm may be used to give priority to a
distinct engine operating mode. If a distinct engine operating mode
is detected, the routine continues at 432, otherwise, the routine
continues at 440.
[0046] At 432, engine 106 may be adjusted according to the distinct
engine operating mode detected at 430. In one example, when tunnel
operating mode is detected, engine 106 may be adjusted in
preparation for entering a tunnel or for operation in a tunnel. In
another example, when boost limiting mode is detected, bypass path
230 may be completely or partially opened during high throttle
settings to reduce boost pressure in intake manifold 218. Each
distinct engine operating mode may adjust engine 106 to increase
desirable outputs and/or decrease undesirable outputs of engine
106. The routine exits after 432.
[0047] At 440, it is determined if a transient engine condition is
detected. During a transient engine condition, turbocharger 220 may
be operating outside of high efficiency island 330. Non-limiting
transient engine conditions may include an acceleration of the
engine or the vehicle, changing a throttle setting, and changing
emissions requirements. If a transient engine condition is
detected, the routine proceeds to 442, otherwise, the routine
proceeds to 450.
[0048] At 442, bypass path 230 is adjusted to provide a path for
gas to flow from upstream of intake manifold 218 through bypass
path 230 to upstream of turbine 226. In one example, gas may flow
from passage 212 through heater 236 to passage 246 if bypass path
230 was adjusted to use heated gas at 424. In another example, gas
may flow from passage 216 to passage 246 if bypass path 230 was
adjusted to use cooled gas at 422. Furthermore, bypass path 230 may
be adjusted according to the magnitude of the transient engine
condition. In one example, bypass path 230 may be fully opened if
the transient engine condition exceeds a threshold. In another
example, bypass path 230 may be partially opened (e.g., the degree
of opening may be proportional to the magnitude of the transient
engine condition) if the transient engine condition is below a
threshold. The routine proceeds to 450 from 442.
[0049] At 450, the notch setting is compared to a speed threshold.
The speed threshold may be determined as those notch settings for
which turbocharger 220 is operating outside of high efficiency
island 330. For the example embodiment of locomotive 100, the lower
notch settings of throttle control 114 may cause turbocharger 220
to operate outside of high efficiency island 330. As a non-limiting
example, the lower notch settings may include notches below six and
a speed threshold may be set at six. If the notch setting is less
than the speed threshold, turbocharger 220 may be operating
inefficiently and the routine proceeds to 452. If the notch setting
is greater than or equal to the speed threshold, turbocharger 220
may be operating efficiently and the routine proceeds to 454.
[0050] At 452, bypass path 230 is adjusted to provide a path for
gas to flow from upstream of intake manifold 218 through bypass
path 230 to upstream of turbine 226. The gas from upstream of
intake manifold 218 may be heated or cooled as determined at 420,
422, and 424. Furthermore, bypass path 230 may be adjusted
according to a difference between the notch setting and the speed
threshold. For example, the lower throttle settings may receive a
greater benefit when more gas is allowed to flow through bypass
path 230. Thus, the degree of opening of bypass path 230 may be
proportional to the difference between the notch setting and the
threshold. The routine exits after 452.
[0051] At 454, bypass path 230 is closed so that gas cannot flow
from upstream of intake manifold 218 to upstream of turbine 226.
For example, valves 232 and 234 may be closed to stop the flow of
gas through bypass path 230. The routine exits after 454.
[0052] In this manner, routine 400 has the technical effect of
adjusting bypass path 230 to selectively route gas from downstream
of compressor 222 to upstream of turbine 226. By adjusting bypass
path 230 during appropriate engine operating conditions, as
elaborated in FIG. 4, the operating point of turbocharger 220 may
be moved from a less efficient operating point to a more efficient
operating point, as elaborated in the prophetic data in FIG. 3, and
gas flow to engine 106 may be increased.
[0053] FIG. 5 illustrates a high level flow chart of an embodiment
of a method of operating an engine in a vehicle, when the vehicle
is within range of a geographic feature, such as when the vehicle
is near or in a tunnel. A tunnel may alter the engine operating
conditions of engine 106 and so adjustments to engine 106 prior to
and while in the tunnel may be desirable. For example, exhaust from
engine 106 or from another engine in the tunnel may be inhaled at
inlet 210 which may increase the temperature and lower the oxygen
content of gas entering inlet 210. The lower oxygen content of
inlet gas may reduce the power output from engine 106 and the
higher temperature of inlet gas may propagate to turbine 226
causing further reduction in power output from engine 106 so
turbine 226 does not overheat. Ingesting exhaust gasses may be more
pronounced when locomotives are coupled in series including a lead
locomotive upstream of one or more downstream locomotives. For
example, a downstream locomotive may ingest exhaust gasses from
each locomotive upstream of the downstream locomotive. The
downstream locomotives may ingest additional exhaust gasses in a
tunnel and/or outside of a tunnel. The embodiment of the method in
FIG. 5 may be implemented as routine 500, which may be called as a
subroutine, such as from 432, for example. Code for routine 500 may
be encoded as instructions stored on a computer readable storage
medium, such as memory 202, and the instructions may be executed by
processor 201 of controller 110.
[0054] Routine 500 begins at 510, where it is determined if the
vehicle is within a threshold range of a geographic feature, such
as a tunnel entrance. The threshold range may be a predetermined
range or the threshold range may be calculated. In one example, the
threshold range is predetermined and stored in a look-up table. The
predetermined threshold range may be a constant for all geographic
features, or the predetermined threshold range may differ for each
known geographic feature. For example, the threshold range may be
100 meters when approaching a short tunnel with a flat grade, but
the threshold range may be 2 kilometers when approaching a long
tunnel with a steep grade. In another example, the threshold range
may be calculated based on engine operating conditions and/or on
characteristics of an approaching geographic feature. For example,
the speed of the vehicle, the throttle setting, the position of a
vehicle in a series of vehicles, and the length of a tunnel may be
used to calculate the threshold range. In one example, a downstream
locomotive may have a threshold range that is greater a threshold
range of an upstream locomotive. If the vehicle is within a
threshold range of a tunnel entrance, the routine proceeds to 520,
otherwise, the routine proceeds to 530.
[0055] At 520, bypass path 230 is adjusted to route cool gas
upstream of turbine 226 when the vehicle is approaching a tunnel
entrance. For example, a first port of valve 232 in communication
with passage 212 may be closed, a second port of valve 232 in
communication with passage 216 may be opened, a first port of valve
234 in communication with heater 236 may be closed, and a second
port of valve 234 in communication with passage 246 may be opened.
In this manner, cool gas may flow from downstream of intercooler
214 to upstream of turbine 226 which may cool turbine 226. The
bypassed gas may also lower the oxygen reaching cylinder banks 240
and 250 as the vehicle approaches the tunnel so that oxygen levels
are similar before and in the tunnel. Gas flow through bypass path
230 may be adjusted according to engine and/or vehicle operating
conditions. For example, a downstream locomotive may adjust bypass
path 230 to flow more gas than an upstream locomotive, during
operating in or near the tunnel. The routine exits after 520.
[0056] At 530, it is determined if the vehicle is in a tunnel. The
determination may be made by an operator signaling the condition,
by an electronic signal in the tunnel, by calculating the position
of the vehicle from GPS signals, or by determining if a tunnel
override flag is set, for example. In one example, a vehicle, such
as a downstream locomotive, may set a tunnel override flag so the
vehicle operates as if the vehicle is in a tunnel. If the vehicle
is in a tunnel, the routine proceeds to 540, otherwise the routine
proceeds to 550.
[0057] At 540, the vehicle is in a tunnel and bypass path 230 is
closed and EGR system 260 is stopped. When operating in a tunnel,
the gas entering inlet 210 may include exhaust gasses from engine
106 or other engines operating in the tunnel. The exhaust gasses
entering inlet 210 could cause engine 106 to behave as if it is
connected to a low pressure EGR system in addition to EGR system
260 and the concentration of exhaust gasses in intake manifold 218
could exceed the desired concentration of exhaust gasses. Thus, by
stopping or decreasing gas flow from EGR system 260, the exhaust
concentration may be maintained at a more desirable level. In an
alternative embodiment, the concentration of exhaust gasses may be
measured in intake manifold 218, and EGR system 260 may be
partially or completely stopped depending on the concentration of
exhaust gasses in intake manifold 218. EGR system 260 may be
stopped by stopping the flow of fuel to the cylinders of cylinder
bank 250. By closing bypass path 230, all available oxygen from the
gas entering inlet 210 may be delivered to intake manifold 218 for
combustion by the cylinders of cylinder bank 240. The routine exits
after 540.
[0058] At 550, the vehicle is no longer in the tunnel and tunnel
operating mode may be stopped and EGR system 260 may be enabled.
When the vehicle exits the tunnel, exhaust gasses and oxygen
entering inlet 210 may return to concentrations similar to the
concentrations before entering the tunnel and the flow of gas from
EGR system 260 may be increased. Thus, bypass path 230 may be
adjusted according to other aspects of routine 400. The routine
exits after 550.
[0059] In this manner, routine 500 has the technical effect of
operating an engine in a vehicle, when the vehicle is within range
of a geographic feature, such as when the vehicle is near or in a
tunnel. By adjusting bypass path 230 and EGR system 260 during
tunnel operating mode, as elaborated in FIG. 5, engine power output
may be increased when the vehicle is in the tunnel, for example.
Increasing the flow of cool gas flow from downstream of compressor
222 to upstream of turbine 226 before a tunnel may cool turbine 226
prior to ingesting hot exhaust gasses in the tunnel. Thus, the
turbine inlet temperature may stay below the turbine inlet
temperature threshold longer than if the turbine was not cooled.
While in the tunnel, decreasing the flow of gas from EGR system 260
may increase the oxygen content flowing to engine 106 and may
increase engine power output of the vehicle.
[0060] The engine illustrated in FIG. 2 may also be used in other
off-highway vehicles, such as the example embodiment of a marine
vehicle in FIG. 6. As depicted herein, marine vehicle 600 may
include a diesel propulsion system for driving a propeller. In one
embodiment, engine 106 may generate torque to drive a propeller
630. Specifically, engine 106 may be connected to a coupling device
610 which may configured to selectively engage or disengage with a
propeller shaft 620 connected to propeller 630. In one embodiment,
coupling device 610 may include a clutch. In another embodiment,
coupling device 610 may include a clutch and a gear box to enable
torque modulation. In one embodiment, the rotational speed of
propeller shaft 620 may be measured by a speed sensor 640, such as
a hall effect sensor. Controller 110 may communicate with engine
106 to control components of engine 106 and to collect sensor data.
Controller 110 may control coupling device 610 and receive
propeller speed data from speed sensor 640. In the depicted
example, propeller 630 is a fixed pitch propeller (FPP). In an
alternate embodiment, propeller 630 may be a controllable pitch
propeller (CPP). Thus, a propeller load being driven by the torque
of engine 106 may depend on the characteristics of coupling device
610, the pitch of propeller 630, and the speed of propeller
630.
[0061] During operation, engine 106 of marine vehicle 600 may go
through various accelerations and decelerations. For example, the
operator may adjust a power output for marine vehicle 600 by
operating a throttle control 650. In one example, it may be
desirable to increase acceleration of marine vehicle 600 by
adjusting bypass path 230 of engine 106. In another example, it may
be desirable to reduce or eliminate turbocharger surge during
deceleration of engine 106. For example, pressure of the outlet of
compressor 222 may not decrease at the same rate as engine rpm and
mass air flow during deceleration. Thus, the operating point of
turbocharger 220 may move closer to surge line 310 than may be
desirable. FIG. 7 illustrates a method 700 for operating engine 106
when engine 106 is included on a marine vehicle.
[0062] At 710, the intake manifold pressure, the engine speed, and
propeller load may be determined. The pressure of gas in intake
manifold 218 may be measured with pressure sensor 206. The engine
speed may be measured with speed sensor 245. In one example, the
propeller load may be negligible when propeller shaft 620 is
disengaged by coupling device 610. In another example, the
propeller load may be a function of the pitch of propeller 630 and
the speed of propeller 630 when propeller shaft 620 is engaged by
coupling device 610. From 710, the routine continues at 720.
[0063] At 720, it is determined if engine 106 is decelerating at a
rate faster than a threshold. In one embodiment, the engine speed
may be measured and recorded at periodic intervals. A current
engine speed may be compared to an engine speed recorded at an
earlier time. If the current engine speed is less than the earlier
engine speed, then engine 106 may be decelerating. In an alternate
embodiment, the output of throttle control 650 may be measured and
recorded at periodic intervals. A current throttle output may be
compared to a throttle output recorded at an earlier time. If the
current throttle output is less than the earlier throttle output,
then engine 106 may be decelerating. In one example, the threshold
may be zero and any deceleration may cause the routine to continue
at 730. In another example, the threshold may be greater than zero
and small decelerations less than the threshold may be handled as
if no deceleration occurred. If the deceleration is less than the
threshold, the routine may continue 740, otherwise the routine may
continue at 730. In one embodiment, the threshold may vary over the
operating range of engine 106. For example, some engine speeds may
be more prone to surge and so the threshold for deceleration may be
lower at these engine speeds.
[0064] At 730, it is determined that engine 106 is decelerating.
Thus, bypass path 230 may be adjusted according to pressure of
intake manifold 218, engine speed, and propeller load. For example,
bypass path 230 may be opened to decrease the pressure of intake
manifold 218 by routing gas from downstream of compressor 222 to
upstream of turbine 226 via bypass path 230. The degree of opening
may be determined according to pressure of intake manifold 218,
engine speed, and propeller load. In one embodiment, a
predetermined look-up table may map the manifold pressure, engine
speed, and propeller load variables to a degree of opening for
bypass path 230. The look-up table may be generated from a
compressor map, such as compressor map 300 of turbocharger 220, for
example. In one embodiment, calculating the propeller load may be
simplified by determining whether propeller 630 is engaged or not
engaged. For example, bypass path 230 may be adjusted according to
one look-up table when propeller 630 is engaged and bypass path 230
may be adjusted according to a different look-up table when
propeller 630 is not engaged. Thus, each look-up table may be
indexed according to the manifold pressure and engine speed. In an
alternative embodiment, bypass path 230 may be adjusted when
propeller 630 is engaged and bypass path 230 may not be adjusted
when propeller 630 is disengaged. The routine may end after
730.
[0065] At 740, it is determined if engine 106 is accelerating at a
rate faster than a threshold. Similar to calculating deceleration,
a series of engine speed or throttle output measurements may be
used to calculate acceleration. If the engine speed is increasing,
then engine 106 may be accelerating. In one example, the threshold
may be zero and any acceleration may cause the routine to continue
at 750. Alternatively, small accelerations may be filtered by
selecting a non-zero threshold for acceleration. If acceleration is
less than the threshold, then the routine may end. In one
embodiment, the threshold may vary over the operating range of
engine 106. For example, some engine speeds may operate in less
efficient areas of compressor map 300 and so the threshold for
acceleration may be lower at these engine speeds.
[0066] At 750, it is determined that engine 106 is accelerating.
Thus, bypass path 230 may be adjusted according to engine speed and
propeller load. For example, bypass path 230 may be opened to
increase gas flow through compressor 222 and to move the
turbocharger operating point to a more efficient operating point on
compressor map 300. Opening bypass path 230 may route gas from
downstream of compressor 222 to upstream of turbine 226. In one
embodiment, all or a portion of the gas flowing through bypass path
230 may be heated by heater 236 as it is routed upstream of turbine
226. The degree of opening and/or heating may be determined
according to engine speed and propeller load. In one embodiment, a
predetermined look-up table may map the engine speed and propeller
load variables to a degree of opening for bypass path 230. In one
embodiment, calculating the propeller load may be simplified by
determining whether propeller 630 is engaged or not engaged. For
example, bypass path 230 may be adjusted according to one look-up
table when propeller 630 is engaged and bypass path 230 may be
adjusted according to a different look-up table when propeller 630
is not engaged. In an alternative embodiment, bypass path 230 may
be adjusted when propeller 630 is engaged and bypass path 230 may
not be adjusted when propeller 630 is disengaged. The routine may
end after 750.
[0067] Certain embodiments of the invention include a bypass path
230 configured to selectively route gas (e.g., air) from downstream
of a compressor 222 to upstream of a turbine 226 (the compressor
and turbine being part of a turbocharger 220). In an embodiment,
the gas that is routed through the bypass path 230 is shunted
around (i.e., bypasses) a combustion portion of the engine 106
where gas is combined with fuel and combusted for driving a
mechanical output shaft of the engine or otherwise, e.g., such
combustion portion typically including an engine block, cylinder
banks 240 and/or 250, cylinders 242, 252, and equipment (such as
fuel injectors) for introducing fuel into the cylinders in a
controlled manner. Thus, in an embodiment, gas routed through the
bypass path 230 is not involved in a fuel/gas combustion event in
the engine 106. In another embodiment, at least part of the bypass
path 230 is a direct path between downstream of the compressor 222
and upstream of the turbine 226, meaning a direct fluid connection
between the compressor downstream and turbine upstream but for any
bypass path flow control devices (e.g., valves 232, 234), and
without any engine or other components that modify or affect the
gas (e.g., intercooler 214, heater 236) other than, again, bypass
path flow control devices (e.g., valves 232, 234) and related
plumbing. Unless otherwise specified, such as in the claims, this
does not preclude the possibility of another part of the bypass
path not being a direct path.
[0068] In another embodiment, the bypass path 230 is solely a
direct path between downstream of the compressor 222 and upstream
of the turbine 226, meaning (i) the bypass path comprises a direct
fluid connection between the compressor downstream and turbine
upstream but for any bypass path flow control devices (e.g., valves
232, 234), and without any engine or other components that modify
or affect the gas (e.g., intercooler 214, heater 236) other than,
again, bypass path flow control devices (e.g., valves 232, 234) and
related plumbing; and (ii) there is no portion of the bypass path
that is not a direct path.
[0069] In another embodiment, at least part of the bypass path 230
is an indirect path between downstream of the compressor 222 and
upstream of the turbine 226, meaning there is at least one engine
or other component that modifies or affects the gas (e.g.,
intercooler 214, heater 236), which is disposed somewhere along the
bypass flow route (e.g., extending from the compressor output,
through at least part of the bypass path, and to the turbine
input), and which is in addition to any flow control devices (e.g.,
valves 232, 234) of the bypass path. In other words, in an indirect
path, at least some of the gas that is routed through the bypass
path is subjected to an engine or other component that modifies or
affects the gas (the engine or other component being in addition to
any flow control devices of the bypass path), somewhere between the
compressor output and turbine input.
[0070] In another embodiment, the bypass path 230 is solely an
indirect path between downstream of the compressor 222 and upstream
of the turbine 226, meaning (i) there is at least one engine or
other component that modifies or affects the gas (e.g., intercooler
214, heater 236), which is disposed somewhere along the bypass flow
route (e.g., extending from the compressor output, through at least
part of the bypass path, and to the turbine input), and which is in
addition to any flow control devices (e.g., valves 232, 234) of the
bypass path; and (ii) there is no portion of the bypass path that
is a direct path.
[0071] In an embodiment, normal operational gas flow through the
engine 106 is from the inlet 210, through the compressor 222,
between the compressor and turbine 226 (e.g., through the engine
cylinders for combustion, or otherwise), through the turbine, and
out the exhaust system. Thus, "upstream" refers to a direction
towards the inlet (against the direction of the normal operational
gas flow), and "downstream" refers to a direction towards the
exhaust (in the direction of the normal operational gas flow).
[0072] This written description uses examples to disclose the
invention, including the best mode, and also to enable a person of
ordinary skill in the relevant art to practice the invention,
including making and using any devices or systems and performing
any incorporated methods. The patentable scope of the invention is
defined by the claims, and may include other examples that occur to
those of ordinary skill in the art. Such other examples are
intended to be within the scope of the claims if they have
structural elements that do not differ from the literal language of
the claims, or if they include equivalent structural elements with
insubstantial differences from the literal languages of the claims.
Moreover, unless specifically stated otherwise, any use of the
terms first, second, etc., do not denote any order or importance,
but rather the terms first, second, etc., are used to distinguish
one element from another.
* * * * *