U.S. patent application number 11/289208 was filed with the patent office on 2007-12-13 for turbo-lag compensation system for an engine.
Invention is credited to Al Berger, Thomas Leone.
Application Number | 20070283939 11/289208 |
Document ID | / |
Family ID | 38820614 |
Filed Date | 2007-12-13 |
United States Patent
Application |
20070283939 |
Kind Code |
A1 |
Berger; Al ; et al. |
December 13, 2007 |
TURBO-LAG COMPENSATION SYSTEM FOR AN ENGINE
Abstract
A boost system for an engine, comprising an engine having at
least a cylinder; a fuel injector coupled to said cylinder; a
compression device coupled to said engine; a compressed air storage
device coupled to said compression device and configured to deliver
compressed air to an air flow amplifier device located in the inlet
air passageway to said cylinder; and a controller to adjust an
amount of fuel injection to account for variation of air delivered
to said cylinder from said flow amplifier device.
Inventors: |
Berger; Al; (Brownstown,
MI) ; Leone; Thomas; (Ypsilanti, MI) |
Correspondence
Address: |
ALLEMAN HALL MCCOY RUSSELL & TUTTLE, LLP
806 S.W. BROADWAY, SUITE 600
PORTLAND
OR
97205
US
|
Family ID: |
38820614 |
Appl. No.: |
11/289208 |
Filed: |
November 28, 2005 |
Current U.S.
Class: |
123/585 ;
123/26 |
Current CPC
Class: |
F01L 3/06 20130101; F02B
23/104 20130101; Y02T 10/12 20130101; F02B 2075/125 20130101; Y02T
10/123 20130101; F02B 21/00 20130101; F02D 41/402 20130101; F01L
3/20 20130101; Y02T 10/146 20130101; F02M 2023/008 20130101; Y02T
10/44 20130101; Y02T 10/40 20130101; F01L 3/22 20130101; F02B 29/02
20130101; F02B 37/00 20130101 |
Class at
Publication: |
123/585 ;
123/026 |
International
Class: |
F02M 23/04 20060101
F02M023/04 |
Claims
1. A boost system for an engine, comprising: an engine having at
least a cylinder; a fuel injector coupled to said cylinder; a
compression device coupled to said engine; a compressed air storage
device coupled to said compression device and configured to deliver
compressed air to said cylinder through an air amplifier device;
and a controller to adjust an amount of fuel injection to account
for variation of air mass delivered to said cylinder through said
air amplifier device.
2. The system of claim 1 wherein said air amplifier device is an
air ejector assembly, used by itself or in conjunction with a
turbocharger or supercharger.
3. The system of claim 1 wherein said air amplifier device is an
air ejector assembly, and wherein said injector is a direct
injector.
4. The system of claim 3 wherein said controller further adjusts an
amount of said air mass delivered in response to a desired output
demand.
5. The system of claim 3 wherein said controller further adds at
least some fuel from said direct fuel injector after intake valve
closing of said cylinder to account for additional air entering
said cylinder.
6. The system of claim 3 wherein said controller further adjusts
said amount of fuel in response to an exhaust gas oxygen
sensor.
7. The system of claim 6 wherein said controller varies an air flow
produced by said air amplifier device in response to variation in
operating conditions.
8. The system of claim 3 wherein said controller determines said
fuel amount in response to air flow through said air-amplifier
device.
9. The system of claim 1 wherein said air flow delivered to said
cylinder is delivered by an ejector assembly using a primary nozzle
built into a valve seat.
10. The system of claim 1 wherein said injector is a direct
injector, and wherein said controller initiates multiple injections
during a cycle of said cylinder to deliver said amount of fuel
injection.
11. The system of claim 10 wherein a first injection is performed
at least partially during an intake stroke, and a second injection
is performed after said first injection, and at least partially
after intake valve closing of said cylinder.
12. The system of claim 10 wherein a first injection is performed
at least partially during an intake stroke, and a second injection
is performed after said first injection, and at least partially
during an early part of a compression stroke.
13. A boost system for an engine, comprising: an engine having at
least a cylinder; a fuel injector coupled to said cylinder; an air
amplifier device coupled into the air passageway to said cylinder;
a compression device coupled to said engine; a compressed air
storage device coupled to said compression device and configured to
selectively deliver compressed air to said air amplifier device;
and a controller to determine an amount of air entering said
cylinder during said selective delivery of said compressed air to
the air amplifier and to adjust an amount of fuel injection to
account for increase of said air mass inducted into said cylinder,
and thereby maintain a desired air-fuel ratio about
stoichiometry.
14. The system of claim 13 wherein said controller estimates an
amount of additional fuel to add based on an air amplifier inlet
pressure, engine speed, and intake manifold pressure.
15. The system of claim 13 wherein timing of said selective
delivery is controlled by cylinder intake valve timing and
position.
16. The system of claim 15 further comprising a valve seat insert,
and wherein said compressed air is delivered to said insert.
17. The system of claim 16 wherein said insert includes a
converging-diverging nozzle.
18. A method for controlling engine operation of an engine having a
turbocharger, a compressed air storage system coupled to said
engine, said system selectively providing enhanced air flow to
cylinders of the engine, the method comprising: during a driver
tip-in event under conditions where said turbocharger is operating
below a selected threshold, selectively providing said compressed
air to the cylinder and adjusting a fuel injection amount to
maintain a desired air-fuel ratio, where said fuel injection is
delivered in at least two separate injections during a cylinder
cycle at least for one cylinder cycle.
19. The method of claim 18 wherein said engine is a gasoline
engine, and wherein said compressed air is provided through an air
flow amplifier system coupled to the engine.
20. The method of claim 19 wherein said selective providing of
compressed air is performed through a converging-diverging nozzle
in a valve seat.
21. A boost system for an engine, comprising: an engine having at
least a cylinder; a direct fuel injector coupled to said cylinder;
a turbocharger device coupled to said engine; a compressed air
storage device coupled to said engine and configured to selectively
deliver compressed air to said cylinder; an air flow amplifier
device coupled to the inlet air passageway to said cylinder,
wherein said compressed air storage device is configured to
selectively deliver compressed air through said flow amplifier
device; and a controller to adjust a timing of direct fuel
injection when delivering compressed air to said cylinder from said
compressed air storage device.
22. (canceled)
Description
BACKGROUND AND SUMMARY
[0001] Engines may use boosting devices, such as turbochargers, to
increase engine power density. Thus, under steady state operation,
smaller displacement, turbocharged engines can produce power
equivalent to larger displacement engines. However, under dynamic
driving conditions, the smaller turbocharged engine may have less
transient performance than a larger, naturally aspirated
engine.
[0002] As one example, when a turbocharged engine is operating at
low load, the turbocharger speed is low and intake manifold
pressure is low. When the engine load is suddenly increased, there
may be a lag before the turbocharger speed increases and intake
manifold pressure rises. This delay may be referred to as
"turbo-lag." During this delay, the engine power or torque output
may be less than desired value, and less than the steady state
available output.
[0003] One approach that attempted to provide intake manifold
pressure boost with minimal delay is described in SAE paper 670109,
published in 1967. This system used storage tanks to store
compressed air with a carbureted, otherwise naturally aspirated
gasoline engine. In this system, when the system was actuated,
desired boost pressures were achieved rapidly.
[0004] Another approach is described in JP 59-99028. This system
uses a compressed-air injecting port receiving air from a
compressed-air tank, where the port was formed in a valve seat of
the intake valve, and said port is opened when the intake valve is
opened. An on-off valve is opened transiently for a prescribed
period when an accelerator pedal is rapidly depressed. When the
intake valve is open, air is injected through the valve seat for
supplementing lack of air caused transiently when the accelerator
pedal is depressed. Specifically, when the accelerator pedal
depression signal exceeds a prescribed value, the on-off valve is
opened by a computer for a prescribed period corresponding to the
pedal depressing speed. With such a system, boost compensation is
allegedly unnecessary.
[0005] However, the inventors herein have recognized disadvantages
with each of the above approaches. For example, if using the
storage approach of SAE 670109 on an otherwise naturally aspirated
engine, boost was provided for only a limited time since storage
tanks were the only source of compressed air. Further, the system
required two tanks of about 12 inches in diameter each, thus
requiring significant packaging space in the vehicle.
[0006] Likewise, regarding the approach in the abstract of JP
59-99028, significant air-fuel ratio control errors may be
encountered if such a system were applied to a gasoline engine.
Specifically, the additional air provided by the boost system may
not be measured by a manifold pressure sensor or mass airflow
sensor in the intake manifold, and thus the amount of fuel supplied
may not match the total inducted airflow, resulting in an air-fuel
ratio excursion. Furthermore, it does not appear that the energy of
compression of the added air is used to amplify air flow through
the main intake port. This means that the compressed air tank must
be large enough to supply all of the desired increase of intake air
mass.
[0007] Thus, in one approach, the above disadvantages may be
overcome by a system for a vehicle traveling on the road. The
system comprises: an engine having at least a cylinder; a fuel
injector coupled to said cylinder; a compression device coupled to
said engine; a compressed air storage device coupled to said
compression device and configured to deliver compressed air to said
cylinder through an air amplifier device; and a controller to
adjust an amount of fuel injection to account for variation of
compressed air delivered to said cylinder from said compressed air
storage device.
[0008] In this way, it is possible to provide accurate fueling
amounts, even when unexpected changes in an amount of compressed
air are encountered before or during an intake event. Further, the
ability to provide rapid response to variations in delivered
compressed air enables further exploitation of the ability to
accommodate the earliest possible induction of such compressed air,
thereby further increasing engine transient responsiveness.
[0009] Note that various types of fuel injectors may be used, such
as side direct injection, overhead direct injection, and port
injection.
DESCRIPTION OF THE FIGURES
[0010] FIGS. 1-3 are each a schematic diagram of an engine;
[0011] FIG. 4 shows a schematic diagram of an example air storage
system that may be used with various types of engines, such as
those in FIG. 1-3;
[0012] FIGS. 5-7 show example embodiments of ejector systems that
may be used with the storage system of FIG. 4;
[0013] FIGS. 8-10 show high level flowcharts of example engine
operation; and
[0014] FIG. 11 shows a graph illustrating available time for fuel
injection.
DETAILED DESCRIPTION
[0015] As noted above, the present application describes an
approach that provides boost compensation to reduce effects of
compressor delays, such as the phenomena known as turbo-lag, as
well as improve various other engine operations, such as engine
cold starting. In one particular example, a separate source of
compressed air is available to be rapidly supplied to the engine
(e.g., via the intake manifold, intake port, or cylinder head)
during selected conditions, such as in response to an accelerator
pedal tip-in, thus reducing turbo-lag. The additional air from the
air amplifier serves to provide a rapid increase in cylinder
charge, even when the turbocharger has not yet attained sufficient
speed to generate the desired pressure boost. Furthermore, the
injection of higher pressure air into the engine cylinders results
in an almost immediate increase in exhaust flow, which enhances
function of the turbocharger, and thus can further reduce the
turbo-lag period. In other words, it is possible to create more
flow into the cylinder than what comes from a compressed air
source, but in one example, this air flow amplification is
implemented only until the turbocharger comes up to speed.
[0016] In one example, the separate compressed air supply may be
provided upstream of the engine between the engine air filter and
the intake manifold, either before of after the turbocharger.
Alternatively, the compressed air could be supplied in the intake
manifold or cylinder head. Further, an ejector may be used to
create an ejector boost system. For example, an ejector may be
integrated into a valve seat to further improve operation. In still
another example, the system may be applied in direct injection
gasoline engines to achieve improved air-fuel ratio control, or
applied to improve engine cold starting of gasoline or diesel
engines.
[0017] In this way, it is possible to utilize an air source in
combination with a flow amplifier device to provide improved
operation for an engine using gasoline, diesel, or various other
fuel types.
[0018] Referring now to FIG. 1, internal combustion engine 10,
comprising a plurality of cylinders, one cylinder of which is shown
in FIG. 1, is controlled by electronic engine controller 12. Engine
10 includes cylinder head 46, combustion chamber 30 and cylinder
walls 32 with piston 36 positioned therein and connected to
crankshaft 40. Combustion chamber 30 is shown communicating with
intake manifold 44 and exhaust manifold 48 via respective intake
valve 52 and exhaust valve 54. Each intake and exhaust valve may be
operated by a camshaft, or both may be operated by a common
camshaft. Variable valve timing operation may be used via a
hydraulic actuator. In an alternative embodiment, the valves may be
operated by an electromechanically controlled valve coil and
armature assembly.
[0019] Cylinder 30 is also shown having direct fuel injector 65
coupled thereto for delivering liquid fuel in proportion to the
pulse width of signal FPW from controller 12 via a fuel injection
system 87, which may be a high pressure common rail diesel fuel
system. Fuel system 87 may include a fuel tank, high and low
pressure fuel pumps, and a fuel rail (not shown). The engine 10 of
FIG. 1 is configured such that the fuel is injected directly into
the engine cylinder, which is known to those skilled in the art as
direct injection. In addition, intake manifold 44 is shown
communicating with optional electronic throttle 125.
[0020] Engine 10 is also shown coupled to a turbocharger system
130, which is one example compression device that may be used.
Turbocharger system 130 includes a compressor 132 on the intake
side and a turbine 134 on the exhaust side coupled via a shaft 136.
In an alternative embodiment, a two-stage turbocharger may be used,
if desired. In another alternative embodiment, a supercharger may
be used having a compressor similar to 132 that is driven via the
engine crankshaft 40.
[0021] Universal Exhaust Gas Oxygen (UEGO) sensor 76 is shown
coupled to exhaust manifold 48 upstream of turbine 134 and emission
control device 70. Device 70 may be a NOx catalyst, an SCR
(selective catalytic reduction) catalyst, a particulate filter, or
combinations thereof. A second exhaust gas oxygen sensor 98 is
shown coupled to the exhaust system downstream of catalytic
converter 70. Emission control device temperature is measured by
temperature sensor 77, and/or estimated based on operating
conditions such as engine speed, load, air temperature, engine
temperature, and/or airflow, or combinations thereof.
[0022] Controller 12 is shown in FIG. 1 as a conventional
microcomputer including: microprocessor unit 102, input/output
ports 104, and read-only memory 106, random access memory 108, keep
alive memory 110, and a conventional data bus. Controller 12 is
shown receiving various signals from sensors coupled to engine 10,
in addition to those signals previously discussed, including:
engine coolant temperature (ECT) from temperature sensor 112
coupled to cooling sleeve 114; a position sensor 119 coupled to an
accelerator pedal; a measurement of engine manifold pressure (MAP)
from pressure sensor 122 coupled to intake manifold 44; a
measurement (ACT) of engine air charge temperature or manifold
temperature from temperature sensor 117; and an engine position
sensor from a Hall effect sensor 118 sensing crankshaft 40
position. In a preferred aspect of the present description, engine
position sensor 118 produces a predetermined number of pulses every
revolution of the crankshaft from which engine speed (RPM) can be
determined.
[0023] In some embodiments, the engine may be coupled to an
electric motor/battery system in a hybrid vehicle. The hybrid
vehicle may have a parallel configuration, series configuration, or
variations or combinations thereof.
[0024] Engine 10 further has a pressurized air delivery system for
delivering higher pressure air to the combustion chamber, an
example of which is described in more detail below herein with
regard to FIG. 4.
[0025] FIG. 2 shows an alternative embodiment of a gasoline direct
injection engine 11 similar to that of FIG. 1. In the example of
FIG. 2, cylinder head 46 is shown having fuel injector 66 coupled
thereto for delivering liquid fuel in proportion to the pulse width
of signal FPW from controller 12. Fuel is delivered to fuel
injector 66 by a fuel system (not shown) including a fuel tank,
fuel pump, and fuel rail (not shown). In one example, a low
pressure direct injection system may be used, where fuel pressure
can be raised to approximately 20-30 bar. Alternatively, a high
pressure, dual stage, fuel system may be used to generate higher
fuel pressures. FIG. 2 also shows distributorless ignition system
88 providing ignition spark to combustion chamber 30 via spark plug
92 in response to controller 12.
[0026] Continuing with FIG. 2, it shows catalytic converter 72,
which can include multiple catalyst bricks, in one example. In
another example, multiple emission control devices, each with
multiple bricks, can be used. Converter 72 can be a three-way type
catalyst in one example.
[0027] Engine 11 also has a pressurized air delivery system for
delivering higher pressure air to the combustion chamber, an
example of which is described in more detail below herein with
regard to FIG. 4.
[0028] In still another alternative example, engine 9 may be a port
injected gasoline engine. Specifically, FIG. 3 shows still another
alternative embodiment of a gasoline port injection engine 9
similar to that of FIGS. 1 and 2. In the example of FIG. 3, an
intake port of manifold 44 is shown having fuel injector 66 coupled
thereto for delivering liquid fuel in proportion to the pulse width
of signal FPW from controller 12.
[0029] Any of engines 9, 10, 11 may be used for road vehicles,
boats, earthmoving equipment, airplanes, generators, pumps,
etc.
[0030] Referring now to FIG. 4, an example air storage system 310
is described that may be coupled to engine 9, 10, or 11.
Specifically, compressed air 312 is directed to the system from a
high pressure compression device (such as a compressor (not
shown)), through one-way check valve 314 to storage tank 316. The
valve 314 enables flow into tank 316, but restricts flow from tank
316 to the compression device. Further, in one example, system 310
also includes control valve 318, receiving a control signal 320
from controller 12, for controlling air via pressure regulator
valve 324 to the air amplifier as described in more detail with
regard to the example embodiments of FIGS. 4-6. In this way, it is
possible to supply higher pressure air to the engine even when
turbocharger pressure buildup is delayed due to turbo-lag, for
example. Further, by using such a system, it is possible to store
compressed air gradually with a smaller compressor, yet provide a
large flow rate for shorter intervals of time, as needed to prevent
turbo-lag.
[0031] The storage pressure in tank 316 may vary depending on the
mass of air stored in the tank, but can vary as high as the
compressor output pressure, which may be 1500 psi or higher.
However, as the duty cycle usage of compressed air in the engine
may be relatively low compared to all engine operation (e.g.,
during turbo-lag conditions, or engine starting conditions, for
example), a low volume, high pressure, compressor can be used to
charge the tank slowly compared to the rate of flow exiting during
use.
[0032] The pressure regulator 324 is generally set to maintain a
pressure of about 150 psi, so that air fed to the primary nozzle
inlet is generally maintained at about this pressure, which may be
significantly higher than manifold pressure. As will be described
in more detail below herein, the primary nozzle then uses this
compressed air at about 150 psi, along with air in the intake
manifold (whose pressure may vary depending on the state of the
turbocharger, engine speed, throttle position, etc.) to create
increased flow into the engine cylinder.
[0033] As noted herein the air amplifier may be referred to as an
ejector assembly, air ejector, air amplifier, and flow
amplifier.
[0034] Referring now to FIG. 5, a first example embodiment for
delivering higher pressure air to engine 9, 10, or 11 is described.
In this example, intake manifold 44 is shown with an intake runner
44a having throat area 44b leading to intake valve 52 and cylinder
30, with a high pressure tube 410 delivering pressurized air.
Specifically, the pressurized air tube 410 is coupled in the intake
manifold and includes a supersonic nozzle 412 directed into each
intake runner (only one of which is shown). In this way, the
manifold plenum serves as an ambient air inlet, the pressurized air
tube 410 serves as a primary nozzle, the manifold runner serves as
a secondary nozzle, the throat of the port (44b) serves as a mixing
tube, and finally the cylinder serves as a diffuser. Such a system
may be generated for each cylinder of the engine by placing a
nozzle in each intake runner. In this way, it is not necessary to
pressurize the entire plenum volume, resulting in faster delivery
of boost pressure to the cylinders, and less heat loss to the
manifold walls for further improvement of engine cold start.
[0035] In example operation, each individual nozzle may be fitted
with a valve to synchronize the nozzle flow with intake valve open
position, in addition to control of pressurized air via valve 318.
In an alternative embodiment, the plurality of nozzles may be
controlled via a single valve.
[0036] Referring now to FIG. 6, a second example embodiment for
delivering higher pressure air to engine 9, 10, or 11 is described.
Specifically, FIG. 6 shows a sectional view of a second example
embodiment for delivering higher pressure air to engine 9, 10, or
11. In this example, intake manifold runner 44a is shown leading to
intake valve 52. Valve 52 seats against a unitary valve insert/seat
512 located in cylinder head 510. Insert 512 includes a port
portion 520 and a head portion 522. Insert 512 includes an annular
supersonic nozzle 514 formed in insert 512. The nozzle may have a
converging-diverging shape as shown in FIG. 6. Pressurized air may
be delivered via one or more delivery tubes 530 to the annular
nozzle 514.
[0037] In this way, it is possible to incorporate a supersonic
nozzle into the cylinder head, with at least one nozzle at each
cylinder. When the intake valve is closed, as shown in FIG. 6, the
pressurized air outlet is blocked by the intake valve head. When
the intake valve is open, the diverging nozzle formed within the
insert directs a supersonic discharge past the valve head and into
the cylinder, thus forming an ejector with an annular supersonic
nozzle. Thus, the amount of compressed air consumed during delivery
may be reduced since air is delivered only during operation where
the intake valve is open. Further, if a controller is used to
estimate an amount of air delivered via the nozzle, the amount can
be estimated based on intake valve opening and closing timings, as
well as cylinder pressure and upstream (e.g., compressed air
supply) pressure. For example, with variable valve timing of either
the intake and/or exhaust valves, variation in valve timing may
affect the amount of compressed air delivered, such as in the
systems of FIGS. 6-7, for example. Therefore, the controller may
include routines for estimating an amount of compressed air that
accounts for variation in valve opening and/or closing timings.
[0038] Returning to the structure of FIG. 6, by using a unitary
insert, it is possible to provide a supersonic nozzle with reduced
part count, and provide improved ability to control dimensions
allowing improved tolerancing. Further, structural bridges 524 (see
FIG. 6A) may be included within the annular nozzle to attach the
port and head portions to each other and to carry the forces of
installation into the head and impact from the closing of the
intake valve. The bridges may cause interruptions in the annularity
of the nozzle, but should not cause major degradation of function.
For example, the bridge may be designed with a length (in the
direction of flow) longer than a width, thereby providing desired
structural rigidity while reducing impact on flow.
[0039] Referring now to FIG. 7, a sectional view of a third example
embodiment for delivering higher pressure air to engine 9, 10, or
11 is described. In this example, intake manifold runner 44a is
shown leading to intake valve 52. Valve 52 seats against a 2-piece
valve insert/seat 612 located in cylinder head 610. Insert 612
includes a port piece (insert) 620 and a head piece (seat) 622.
Insert 612 thus forms an annular supersonic nozzle 614 formed in
insert 612. Pressurized air may be delivered via one or more
delivery tubes 624 to the annular nozzle 614.
[0040] In this way, it is possible to incorporate a supersonic
nozzle into the cylinder head, with at least one nozzle at each
cylinder. When the intake valve is closed, as shown in FIG. 7, the
pressurized air outlet is blocked by the intake valve head. When
the intake valve is open, the diverging nozzle formed between the
two inserts directs a supersonic discharge past the valve head and
into the cylinder, thus forming an ejector with an annular
supersonic nozzle. Thus, the amount of compressed air consumed
during delivery may be reduced since air is delivered only during
operation where the intake valve is open. Further, if a controller
is used to estimate an amount of air delivered via the nozzle, the
amount can be estimated based on intake valve opening and closing
timings, as well as cylinder pressure and upstream (e.g.,
compressed air supply) pressure.
[0041] Referring now to FIG. 8, a first example embodiment of a
routine for controlling engine operation to reduce turbo-lag is
described. In this example, which may be a diesel or gasoline
engine, the routine first determines engine operating conditions in
710, such as engine speed, engine load, throttle position, intake
manifold absolute pressure, engine temperature, storage pressure of
tank 316, temperature of tank 316, turbine/compressor speed, and
others.
[0042] Then, in 712, the routine determines whether an accelerator
pedal tip-in has occurred under conditions in which turbo-lag may
exist. For example, this may occur during lower turbine speed
conditions, or low mass airflow conditions. If so, the routine
continues to 714 to determine whether compressed air is available,
for example, in response to pressure in tank 316. Further, a need
for additional compressed air may also be based on other
indications, such as a desired engine torque, a rate of change of
desired torque, a driver demanded torque, etc. In addition, or in
the alternative, an indication may also be generated that
additional compressed air is desired during engine cold starting.
For example, a boost of cylinder inlet pressure may result in
higher compression temperatures in the combustion chamber and serve
to improve engine cold starting combustion, especially for a diesel
engine.
[0043] If pressurized air is available, the routine continues to
716 to determine an amount of compressed air to add and/or a
duration of compressed air addition. For example, under some
conditions, it may be advantageous to provide compressed air for a
first number of combustion events, or until a selected turbine
speed is reached, while under other conditions, it may be
advantageous to provide compressed air for a longer duration or a
greater number of combustion events, or to a higher turbine speed.
Further, the routine activates valve 320 to make compressed air
available to the ejector system.
[0044] Next, in 720, the routine determines if the duration (or
other measure) of 716 has elapsed, thus indicating the additional
supply of air is no longer desired. If so, the routine continues to
718 to deactivate compressed air addition, e.g., by deactivating
valve 320. Otherwise, the routine continues to 722 to add
compressed air to the engine's cylinders. For example, the routine
may control additional valves (if present) to control the timing of
addition of compressed air, or may rely on a valve insert ejector
system, as described herein.
[0045] In this way, it is possible to supply additional air when
needed to compensate for turbo-lag. Further, the ejector may be
used only for the duration of turbo-lag period, thus reducing the
size of compressed air storage needed.
[0046] It should be noted that during the period of air injection
at 722, before the desired duration of injection that was
calculated at 716 has been determined at 720 to have elapsed, the
operating conditions and accelerator pedal tip-in status are
continually being monitored at 710 and 712. If there is a change of
conditions, such as a driver "change of mind" with the desired load
being rapidly reduced, a new calculation of desired duration will
be sent to 720 to possibly override a prior decision.
[0047] Referring now to FIG. 9, a second example embodiment of a
routine for controlling engine operation to reduce turbo-lag is
described. In this example, which may be a diesel or gasoline
engine, the routine first determines engine operating conditions in
810, such as engine speed, engine load, throttle position, intake
manifold absolute pressure, engine temperature, storage pressure of
tank 316, temperature of tank 316, turbine/compressor speed, and
others. Then, in 812, the routine determines whether a tip-in or
other condition indicative of a possible turbo-lag, or desire for
compressed air, is present. For example, compressed air may aid
cold start performance, especially for a diesel engine. Also, as
noted with regard to 812, other parameters and factors may also be
used. If the answer to 812 is yes, the routine continues to 814 to
determine an amount and/or duration of compressed air to add in
response to operating conditions, such as those determined in 810.
Then, in 816 the routine adds the extra air to the cylinders as
noted above with regard to FIG. 8.
[0048] Then, the routine determines a fuel amount adjustment based
on the addition of pressurized air. Further, the routine may also
determine an injection timing adjustment as different fuel
injection timing may be used when adding pressurized air from the
injection timing without pressurized air. In the example of a
gasoline engine where air-fuel ratio is controlled to a desired
value, such as about stoichiometry, the routine may determine a
fuel adjustment amount to match the additional air due to the
pressurized air addition and thereby maintain a desired air-fuel
ratio.
[0049] Next, in 820, the routine determines whether multiple
injection may be used, which may be based on whether pressurized
air is added, and other operating conditions. The use of multiple
injections may be used to provide faster fuel injection later in
the induction stroke, rather than waiting for later fueled cylinder
events to match added air. If the answer to 820 is yes, the routine
continues to 822 to select the relative amount of fuel and timing
between the multiple injection events. Then, in 824, the routine
delivers the desired fuel injection (or injections) at the selected
timing (or timings).
[0050] In this way, it is possible to coordinate fuel injection
amounts and/or timing with the addition of pressurized air to
reduce the effects of turbo-lag, while maintaining desired air-fuel
ratio.
[0051] Note that the routine may determine the amount of pressured
air added based on various factors, such as manifold pressure,
pressure in tank 316, intake valve timing, and others. In addition,
or in the alternative, the routine may use pressure sensors or a
mass airflow sensor to measure the amount of air from the ejector
system.
[0052] Referring now to FIG. 10, a routine is described for
controlling pressure of compressed air delivered to the ejector
assemblies. The routine first reads operating conditions in 910,
such as temperature, manifold pressure, etc., and then determines a
desired delivery pressure in 912 based on the operating conditions
of 910. Then, the routine adjusts a parameter, such as an
adjustable pressure regulator valve, to achieve the desired
delivery pressure. In this way, higher pressure may be supplied
under conditions where higher ejector flow is desired, or where
valve opening time is shortened.
[0053] Note that there may be conditions where it could be possible
to add additional air via the ejector assembly, but not possible to
provide matching additional fuel. Under such conditions, delivery
of the additional air may be delayed until matching fuel can also
be provided, such as under stoichiometry control in gasoline
engines.
[0054] Referring now to FIG. 11, a graph illustrates the
advantageous operation of using direct fuel injection with an
ejector compensation system such as described above herein.
Specifically, the graph illustrates the additional interval (from
x1 to x2) available to provide extra fuel injection to compensate
for the additional air from the ejector with a direct injection
system as compared with a port injection system with closed valve
injection.
[0055] For example, assuming a tip-in occurs at the point located,
if using port fuel injection, it may not be desirable to add the
compressed air for the upcoming cylinder whose valve timing is
shown (since the injection of additional fuel also takes a certain
amount of time). However, if direct fuel injection is used, and the
fuel injection duration is lengthened (or a second injection is
used), for example, it may still be possible to compensate the fuel
injection for the additional air, and thus the additional air and
fuel may be provided for the cylinder shown. Such operation may
enable a faster response to the driver tip-in, while still
maintaining a desired combustion air-fuel ratio. In this way, even
if an unexpected driver tip-in occurs, it is still possible to
adjust the fuel and air of a cylinder soon to be fired.
[0056] It will be appreciated that the processes disclosed herein
are exemplary in nature, and that these specific embodiments are
not to be considered in a limiting sense, because numerous
variations are possible. The subject matter of the present
disclosure includes all novel and non-obvious combinations and
subcombinations of the various camshaft and/or valve timings, fuel
injection timings, and other features, functions, and/or properties
disclosed herein.
[0057] Furthermore, the concepts disclosed herein may be applied to
multi fuel engines capable of burning various types of gaseous
fuels and liquid fuels.
[0058] As still another example, the particular location of sensor
measurements may be varied and/or modified. For example, ACT may be
measured before a turbocharger compressor and MAP measure after the
compressor. Such measurement locations may be particularly
advantageous in that the MAP that can be more influential to some
operation of the cylinder(s) is the downstream pressure, and the
ACT sensor may have a time lag that would make it inaccurate during
transients where the boost pressure and resulting temperature is
rapidly changing. Thus, placing the ACT sensor before the
compressor may remain more stable.
[0059] In another embodiment, a spark advance strategy on a
gasoline engine may be adjusted to account for pressurized air
delivery. For example, during ejector function, the controller may
adjust spark advance in an at least partially open loop manner to
accommodate rapid transient conditions since sensor time lags may
be significant. In this way, engine knock that may other occur can
be reduced or avoided during delivery thereby achieving improved
performance.
[0060] The following claims particularly point out certain
combinations and subcombinations regarded as novel and nonobvious.
These claims may refer to "an" element or "a first" element or the
equivalent thereof. Such claims should be understood to include
incorporation of one or more such elements, neither requiring nor
excluding two or more such elements. Other combinations and
subcombinations of the injection and temperature methods,
processes, apparatuses, and/or other features, functions, elements,
and/or properties may be claimed through amendment of the present
claims or through presentation of new claims in this or a related
application. Such claims, whether broader, narrower, equal, or
different in scope to the original claims, also are regarded as
included within the subject matter of the present disclosure.
* * * * *