U.S. patent application number 16/447895 was filed with the patent office on 2019-10-03 for methods and system for diagnosing fuel injectors of an engine.
The applicant listed for this patent is GE Global Sourcing LLC. Invention is credited to Shailesh Nair, Pradheepram Ottikkutti.
Application Number | 20190301392 16/447895 |
Document ID | / |
Family ID | 61241926 |
Filed Date | 2019-10-03 |
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United States Patent
Application |
20190301392 |
Kind Code |
A1 |
Ottikkutti; Pradheepram ; et
al. |
October 3, 2019 |
METHODS AND SYSTEM FOR DIAGNOSING FUEL INJECTORS OF AN ENGINE
Abstract
Various methods and systems are provided for diagnosing a
condition of a fuel injector of an engine. In one example, a method
for an engine includes injecting a first pulse of fuel as a first
pilot injection into a first subset of cylinders of a plurality of
engine cylinders, where the first pilot injection precedes a
primary injection of fuel into the first subset of cylinders by a
duration; correlating a first response in an engine operating
parameter to the first pilot injection; and adjusting the primary
injection of fuel into the first subset of cylinders based on the
first response. In one example, the first pilot injection precedes
the primary injection by a predefined short duration and the
primary injection of fuel is adjusted within a predefined or preset
upper limit and lower limit.
Inventors: |
Ottikkutti; Pradheepram;
(Erie, PA) ; Nair; Shailesh; (Bangalore,
IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GE Global Sourcing LLC |
Norwalk |
CT |
US |
|
|
Family ID: |
61241926 |
Appl. No.: |
16/447895 |
Filed: |
June 20, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15248715 |
Aug 26, 2016 |
10344704 |
|
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16447895 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02D 2041/224 20130101;
Y02T 10/40 20130101; F02D 41/403 20130101; F02D 2200/1002 20130101;
F02D 35/027 20130101; F02D 2200/101 20130101; Y02T 10/44 20130101;
F02D 2200/1012 20130101; F02D 2200/602 20130101; F02D 41/221
20130101 |
International
Class: |
F02D 41/40 20060101
F02D041/40; F02D 41/22 20060101 F02D041/22 |
Claims
1-13. (canceled)
14. A method for an engine, comprising: injecting fuel into each
cylinder of a plurality of cylinders of the engine over a single
engine cycle via a plurality of fuel injectors, where each fuel
injector of the plurality of fuel injectors is coupled to a
different cylinder of the plurality of cylinders; determining
individual engine speed accelerations resulting from the injection
of fuel into each cylinder; and indicating degradation of one or
more of the plurality of fuel injectors in response to a variation
in the determined individual engine speed accelerations being
greater than a threshold acceleration level.
15. The method of claim 14, further comprising indicating which
fuel injector of the plurality of fuel injectors is degraded based
on the individual engine speed accelerations and a known engine
cylinder firing order of the engine.
16. The method of claim 15, wherein indicating degradation
includes: indicating an increase in a size of one or more nozzle
fuel spray holes of the indicated fuel injector in response to the
individual engine speed acceleration resulting from the injection
of fuel via the indicated fuel injector being greater than an
expected engine speed acceleration for a non-degraded fuel
injector; and indicating one or more of a decrease in response time
of a solenoid of the indicated fuel injector or mechanical
degradation of the indicated fuel injector in response to the
individual engine speed acceleration resulting from the injection
of fuel via the indicated fuel injector being less than the
expected engine speed acceleration.
17. A system for an engine, comprising: a plurality of engine
cylinders including at least a first cylinder and a second
cylinder; a first fuel injector coupled to the first cylinder; a
second fuel injector coupled to the second cylinder; and a
controller operatively coupled to the first and second fuel
injectors and configured to: during a first engine cycle, control
injection of a primary pulse of fuel into the first cylinder via
the first fuel injector and the second cylinder via the second fuel
injector and injection of a pilot pulse of fuel, before the primary
pulse, into only the first cylinder via the first fuel injector;
correlate a first response in an engine operating parameter to
injection of the pilot pulse of fuel into the first cylinder; and
during a second engine cycle, following the first engine cycle,
adjust the primary pulse of fuel into the first cylinder based on
the first response to the pilot pulse of fuel.
18. The system of claim 17, wherein the controller is further
configured to: during a third engine cycle, control injection of
the primary pulse of fuel into the first cylinder via the first
fuel injector and the second cylinder via the second fuel injector
and injection of the pilot pulse of fuel, before the primary pulse,
into only the second cylinder via the second fuel injector;
correlate a second response in the engine operating parameter to
injection of the pilot pulse of fuel; and during a fourth engine
cycle, following the third engine cycle, adjust the primary pulse
of fuel into the second cylinder based on the second response to
the pilot pulse of fuel.
19. The system of claim 17, further comprising a real-time engine
torque output sensor coupled to a crankshaft of the engine, wherein
the engine operating parameter is a torque signal output by the
torque output sensor, and wherein the controller is configured to
diagnose a condition of the first injector in response to a change
in the torque output over a number of engine cycles when the pilot
pulse of fuel is injected into the first cylinder via the first
fuel injector.
20. The system of claim 17, further comprising a knock sensor
coupled to the first cylinder, wherein the engine operating
parameter is a knock signal output by the knock sensor, and wherein
the controller is configured to diagnose a condition of the first
injector in response to a change in the knock signal over a number
of engine cycles when the pilot pulse of fuel is injected into the
first cylinder via the first fuel injector.
21. The method of claim 14, wherein the threshold acceleration
levels are based on a commanded amount of the injection of
fuel.
22. The method of claim 21, wherein the determined individual
engine speed accelerations are used to determine an effective
amount of fuel injected.
23. The method of claim 22, wherein fuel is injected into the
engine via a primary injection and a pilot injection.
24. The method of claim 21, wherein an amount of fuel injected is
adjusted based on a difference between the determined individual
engine speed accelerations and the threshold acceleration
level.
25. The system of claim 17, wherein the first response to the
injection of the pilot pulse occurs before the primary injection
into the first cylinder.
26. The system of claim 17, wherein the controller is further
configured to, during a third engine cycle, control an injection of
a pilot pulse of fuel of the third engine cycle, before a primary
pulse of the third engine cycle, into only the first cylinder via
the first fuel injector.
27. The system of claim 26, wherein the controller is further
configured to correlate a response of the third engine cycle in an
engine operating parameter to the injection of the pilot pulse of
the third engine cycle fuel; and determine a difference between the
first response to the injection of the pilot pulse of fuel and the
response of the third engine cycle.
28. The system of claim 27, wherein the controller is further
configured to correlate a response of a further subsequent engine
cycle in an engine operating parameter to an injection of a pilot
pulse of the further subsequent engine cycle into the first
cylinder; and compare the first response to the injection of the
pilot pulse of fuel, the response of the third engine cycle and the
further subsequent engine cycle.
29. The system of claim 28, wherein the controller is further
configured to adjust injections of primary pulses into the first
cylinder based on the comparison of the first response to the
injection of the pilot pulse of fuel, the response of the third
engine cycle and the further subsequent engine cycle.
30. The system of claim 28, wherein the controller is further
configured to indicate degradation when the comparison determines
that responses to pilot injections deviate farther from a threshold
with time.
Description
BACKGROUND
Technical Field
[0001] Embodiments of the subject matter disclosed herein relate to
an engine system including fuel injectors and diagnosing a
condition of the fuel injectors based on a response in an engine
operating parameter (following injecting fuel with the fuel
injectors).
DISCUSSION OF ART
[0002] An engine, such as a diesel engine, may include a fuel
system including a plurality of fuel injectors. In one example, one
fuel injector may be coupled to each cylinder of the multi-cylinder
engine. Each fuel injector may be adapted to inject a pulse of fuel
into the cylinder at a different time in an engine cycle, according
to a cylinder firing order of the engine. A controller of the
engine may assume a uniform injector health over the life of the
injector and may not distinguish between newer and older injectors.
As such, fuel injection parameters of the engine may remain the
same throughout a lifetime of use of the injector. However, over
time, one or more of the injectors may age or become degraded
(e.g., faulty) which may cause the one or more injectors to inject
more or less fuel than expected (or commanded). As a result, engine
emissions may increase and performance of the engine may
decrease.
BRIEF DESCRIPTION
[0003] In one embodiment, a method for an engine (e.g., a method
for controlling an engine system) comprises injecting a first pulse
of fuel as a first pilot injection into a first subset of cylinders
of a plurality of engine cylinders, where the first pilot injection
precedes a primary injection of fuel into the first subset of
cylinders by a duration; correlating a first response in an engine
operating parameter to the first pilot injection; and adjusting the
primary injection of fuel into the first subset of cylinders based
on the first response.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 shows a schematic diagram of a vehicle with an engine
according to an embodiment of the disclosure.
[0005] FIG. 2 shows a schematic diagram of a cylinder of the engine
of FIG. 1, according to an embodiment of the disclosure.
[0006] FIG. 3 shows a flow chart of a method for adjusting fuel
injection via one or more fuel injectors based on a response in an
engine operating parameter following a fuel injector injection
event, according to an embodiment of the disclosure.
[0007] FIG. 4 shows a flow chart of a method for diagnosing a
condition of a fuel injector based on a response in an engine
operating parameter following performing a pilot injection with the
fuel injector, according to an embodiment of the disclosure.
[0008] FIG. 5 shows a flow chart of a method for diagnosing a
condition of one or more fuel injectors based on variations in
engine speed accelerations after injecting fuel into each cylinder,
according to an embodiment of the disclosure.
[0009] FIG. 6 shows a graph of changes to an effective pulse width
of a fuel injector over time and a number of pilot injection
events, according to an embodiment of the disclosure.
[0010] FIG. 7 shows a graph of performing pilot injections at
different cylinders during different engine cycles and adjusting
subsequent fuel injection events based on a response in an engine
operating parameter due to the pilot injections, according to an
embodiment of the invention.
DETAILED DESCRIPTION
[0011] The following description relates to embodiments of
diagnosing a condition of one or more fuel injectors based on a
response in an engine operating parameter following a fuel
injection event of the one or more fuel injectors. In one
embodiment, a method for an engine includes injecting a first pulse
of fuel as a first pilot injection into a first subset of cylinders
of a plurality of engine cylinders, where the first pilot injection
precedes a primary injection of fuel into the first subset of
cylinders by a pre-set duration; correlating a first response in an
engine operating parameter to the first pilot injection; and
adjusting the primary injection of fuel into the first subset of
cylinders based on the first response. In one example, the engine
operating parameter may be engine speed. In another example, the
engine operating parameter may be engine knock. In yet another
example, the engine operating parameter may be engine misfire. In
yet another example, the engine operating parameter may be engine
(individual cylinder generated) torque. A condition of a first fuel
injector injecting the first pulse of fuel may be diagnosed based
on a change in the first response over a number of first pilot
injections. In a different embodiment, where engine instantaneous
torque can be measured, a method for an engine includes injecting
fuel into each cylinder of a plurality of cylinders of the engine
over a single engine cycle via a plurality of fuel injectors, where
each fuel injector of the plurality of fuel injectors is coupled to
a different cylinder of the plurality of cylinders; determining
individual torque output resulting from the injection of fuel into
each cylinder; and indicating degradation of one or more of the
plurality of fuel injectors in response to a variation in the
determined individual engine (cylinder) torque output being greater
than a threshold torque level. In yet another embodiment, a method
for an engine includes injecting fuel into each cylinder of a
plurality of cylinders of the engine over a single engine cycle via
a plurality of fuel injectors, where each fuel injector of the
plurality of fuel injectors is coupled to a different cylinder of
the plurality of cylinders; determining individual engine speed
accelerations resulting from the injection of fuel into each
cylinder; and indicating degradation of one or more of the
plurality of fuel injectors in response to a variation in the
determined individual engine speed accelerations being greater than
a threshold acceleration level.
[0012] FIG. 1 shows an engine including a plurality of cylinders,
each cylinder including a fuel injector. Each time one of the fuel
injector fires (e.g., injects fuel into the cylinder which it is
coupled to), a speed of the engine (e.g., engine speed) may
increase. For example, a spike in engine speed from a baseline
(just prior to injector firing) engine speed may occur following an
injection of fuel into an engine cylinder. The increase in engine
speed may be measured via an engine speed sensor, such as the
crankshaft speed sensor shown in FIG. 2. As a fuel injector ages or
becomes degraded, it may inject a different fuel amount than
commanded in response to a control signal sent to the fuel
injector. By monitoring changes in an operating parameter of the
engine, such as engine speed, engine torque output, engine knock,
or engine misfire, a change in performance (from a baseline or
commanded value) may be determined, thereby enabling diagnosis of
the fuel injectors. In one example, as shown in the method of FIG.
4, a pilot injection may be delivered via a single fuel injector
and a response in an engine operating parameter as a result of the
pilot injection may be used to diagnose the fuel injector. For
example, as shown in FIG. 6, the fuel injector may be diagnosed
based on changes to an effective pulse width of the pilot injection
of the fuel injector over time, where the effective pulse width is
determined based on the response in the engine operating parameter.
Further, as shown in FIG. 7, the method shown in FIG. 4 may be
repeated during different engine cycles for each fuel injector and
the corresponding cylinder which the fuel injector is coupled to.
In another example, as shown in the method of FIG. 5, a primary
injection of fuel may be delivered to each cylinder via the fuel
injectors and the individual engine speed accelerations resulting
from the injection of fuel into each cylinder may be compared
between the cylinders. The variation in engine speed acceleration
between each cylinder, the individual engine speed acceleration
values, and a known firing order of the engine cylinders may then
be used to diagnose the fuel injectors and to identify/determine
which specific fuel injector or injectors are degraded and
injecting less fuel or more fuel, outside of the allowable
tolerance. Additionally, as shown in the method of FIG. 3, fuel
injection via the fuel injectors (e.g., the amount or pulse width
of fuel injected) may then be adjusted based on the diagnosis of
the fuel injectors and/or the determined engine parameter
responses. In this way, a change in performance of one or more fuel
injectors may be diagnosed and engine operation may be adjusted to
account for the change in performance. As a result, engine
emissions may be maintained at a desired level and engine
performance and efficiency may be increased.
[0013] The approach described herein may be employed in a variety
of engine types, and a variety of engine-driven systems. Some of
these systems may be stationary, while others may be on semi-mobile
or mobile platforms. Semi-mobile platforms may be relocated between
operational periods, such as mounted on flatbed trailers. Mobile
platforms include self-propelled vehicles. Such vehicles can
include on-road transportation vehicles, as well as mining
equipment, marine vessels, rail vehicles, and other off-highway
vehicles (OHV). For clarity of illustration, a locomotive is
provided as an example of a mobile platform supporting a system
incorporating an embodiment of the invention.
[0014] Before further discussion of the approach for diagnosing a
change in performance of fuel injectors of an engine, an example of
a platform is disclosed in which the engine may be installed in a
vehicle, such as a rail vehicle. FIG. 1 shows a block diagram of an
embodiment of a vehicle system 100 (e.g., a locomotive system),
herein depicted as vehicle 106. The illustrated vehicle is a rail
vehicle configured to run on a rail 102 via a plurality of wheels
112. As depicted, the vehicle includes an engine system with an
engine 104. In one embodiment herein, the engine is a multi-fuel
engine operating with diesel fuel and natural gas, but in other
examples the engine may use various combinations of fuels other
than diesel and natural gas (such as any combination of diesel,
gasoline, natural gas, or other fuel blends). In yet another
embodiment, the engine may be a single-fuel engine operating with
only one fuel, such as diesel fuel or direct injection of gasoline
(such as GDI) or direct injection of natural gas injected (such as
HPDIGAS) into the engine cylinder.
[0015] The engine receives intake air for combustion from an intake
passage 114. The intake passage receives ambient air from an air
filter (not shown) that filters air from outside of the vehicle.
Exhaust gas resulting from combustion in the engine is supplied to
an exhaust passage 116. Exhaust gas flows through the exhaust
passage, and out of an exhaust stack of the vehicle.
[0016] The engine system includes a turbocharger 120 ("TURBO") that
is arranged between the intake passage and the exhaust passage. The
turbocharger increases air charge of ambient air drawn into the
intake passage in order to provide greater charge density during
combustion to increase power output and/or engine-operating
efficiency. The turbocharger may include a compressor (not shown in
FIG. 1) which is at least partially driven by a turbine (not shown
in FIG. 1). While in this case a single turbocharger is shown,
other systems may include multiple turbine and/or compressor
stages. In other embodiments, the engine system may be naturally
aspirated receiving fresh air charge for in-cylinder combustion and
not include a turbocharger.
[0017] In some embodiments, the engine system may include an
exhaust gas treatment system coupled in the exhaust passage
upstream or downstream of the turbocharger. In one example
embodiment having a diesel engine, the exhaust gas treatment system
may include a diesel oxidation catalyst (DOC) and a diesel
particulate filter (DPF). In other embodiments, the exhaust gas
treatment system may additionally or alternatively include one or
more emission control devices. Such emission control devices may
include a selective catalytic reduction (SCR) catalyst, three-way
catalyst, NOx trap, as well as filters or other systems and
devices.
[0018] A controller (e.g., electronic controller having one or more
processors) 148 may be employed to control various components
related to the vehicle system. In one example, the controller
includes a computer control system. The controller further includes
computer readable storage media (e.g., memory) including code for
enabling on-board monitoring and control of rail vehicle operation.
The controller, while overseeing control and management of the
vehicle system, may receive signals from a variety of sensors 150,
as further elaborated herein, to determine operating parameters and
operating conditions, and correspondingly adjust various engine
actuators 152 to control operation of the vehicle. For example, the
controller may receive signals from various engine sensors
including, but not limited to, engine speed, engine torque output,
engine load, boost pressure, exhaust pressure, ambient pressure,
exhaust temperature, knock, misfire, and the like. Correspondingly,
the controller may control aspects and operations of the vehicle
system by sending commands to various components such as traction
motors, alternator or generator, cylinder valves, air and/or fuel
throttle, fuel injectors, and the like.
[0019] As shown in FIG. 1, the engine includes a plurality of
cylinders 108. Though FIG. 1 depicts an engine with eight
cylinders, other numbers of cylinders are possible. Each cylinder
of the engine may include a knock sensor 110 and a fuel injector
111. Each fuel injector may inject fuel into the cylinder which it
is coupled to at a different time than the other fuel injectors.
The order in which each fuel injector fires (e.g., injects fuel
into the corresponding cylinder) may be referred to herein as the
cylinder firing order. For a single engine cycle, each fuel
injector may fire at a different time within the cylinder firing
order. For example, each fuel injector may deliver one primary
injection into the cylinder which it is coupled to in a single
engine cycle. In some embodiments, as described further below, one
fuel injector of one cylinder for the single engine cycle may
additionally perform a pilot injection, before its primary
injection, in order to diagnose the performance of the fuel
injector (as described further below with reference to FIGS. 3-4
and 6-7).
[0020] In some embodiments, as shown in FIG. 1, the engine includes
one engine crankshaft torque output sensor 113 for the entire
engine, and a torque contribution to the crankshaft from each
individual cylinder can be measured and determined based on torque
data associated with the specific contributing cylinder. In one
example, the torque sensor may be a contact type or contactless
type or slip-ring type. Each of the types may use strain gauge,
piezo-electric, or such other technologies. The torque sensor may
output a voltage which is then received as a voltage signal at the
controller. In one embodiment, the controller processes the voltage
signal from the torque sensor to determine a corresponding
cylinder-by-cylinder torque output for the entire engine, for each
full cycle of engine operation, and subsequently adjust engine
operation based on the received data. In another example, the
controller may determine cylinder misfire based on the output of
the torque sensor, a crankshaft position output (e.g., via a
crankshaft position or speed sensor, as shown in FIG. 2 and
described further below), and a known cylinder firing order of the
engine (e.g., the cylinder number order in which fuel is injected
into each cylinder and then combusted). As described further below
with reference to FIGS. 3-4, the controller may adjust fueling to
the engine cylinders and/or diagnose a condition of the fuel
injectors based on the received data from the torque output
sensor.
[0021] Since the engine includes one knock sensor for each
cylinder, each individual cylinder knock sensor may measure data
associated with the cylinder it is coupled to. In one example, the
knock sensor may be a strain gauge based or accelerometer based
knock sensor. The knock sensor may output a voltage which is then
received as a voltage signal at the controller. In one embodiment,
the controller processes the voltage signal from the knock sensor
to determine a corresponding indicated mean effective pressure
(IMEP) value and/or peak cylinder pressure (PCP) value (or a
maximum acceleration value associated with the PCP) for the
individual cylinder which the knock sensor is coupled to. Thus, the
controller receives data from each knock sensor of each engine
cylinder of the engine and processes the received data to indicate
engine cylinder knock, determine the indicated IMEP and/or PCP, and
subsequently adjust engine operation based on the received data. In
another example, the controller may determine cylinder misfire
based on the output of the knock sensors, a crankshaft position
output (e.g., via a crankshaft position or speed sensor, as shown
in FIG. 2 and described further below), and a known cylinder firing
order of the engine (e.g., the cylinder number order in which fuel
is injected into each cylinder and then combusted). As described
further below with reference to FIGS. 3-4, the controller may
adjust fueling to the engine cylinders and/or diagnose a condition
of the fuel injectors based on the received data from the knock
sensors.
[0022] FIG. 2 depicts an embodiment of a combustion chamber, or
cylinder 200, of a multi-cylinder internal combustion engine, such
as the engine 104 described above with reference to FIG. 1.
Cylinder 200 may be a representative cylinder for cylinders 108 in
FIG. 1. Additionally, the cylinder shown in FIG. 2 may be defined
by a cylinder head 201, housing the intake and exhaust valves and
fuel injector, described below, and a cylinder block 203. In some
examples, each cylinder of the multi-cylinder engine may include a
separate cylinder head coupled to a common cylinder block.
[0023] The engine may be controlled at least partially by a control
system including controller 148 which may be in further
communication with a vehicle system, such as the vehicle system 100
described above with reference to FIG. 1. As described above, the
controller may further receive signals from various engine sensors
including, but not limited to, engine speed from a crankshaft speed
sensor 209, engine load, boost pressure, exhaust pressure, ambient
pressure, CO.sub.2 levels, exhaust temperature, NO.sub.x emission,
engine coolant temperature (ECT) from temperature sensor 230
coupled to cooling sleeve 228, etc. In one example, the crankshaft
speed sensor may be a Hall effect sensor, variable reluctance
sensor, linear variable differential transducer, an optical sensor,
or other types/forms of speed sensors, configured to determine
crankshaft speed (e.g., RPM) based on the speed of one or more
teeth on a wheel of the crankshaft. In another example, the
crankshaft speed sensor may also determine a position of the
crankshaft. Correspondingly, the controller may control the vehicle
system by sending commands to various components such as
alternator/generator, cylinder valves, air and/or fuel throttle,
fuel injectors, etc.
[0024] As shown in FIG. 2, the controller receives a signal (e.g.,
output) from the crankshaft speed sensor. In one example, this
signal (which may be an analog output that includes a pulse each
time a tooth of the wheel of the crankshaft passes the crankshaft
speed sensor) may be converted by a processor of the controller
into an engine speed (e.g., RPM) signal. The controller may then
use the engine speed signal to adjust engine operation (e.g.,
adjust primary fueling to the cylinder).
[0025] The cylinder (i.e., combustion chamber) 200 may include
combustion chamber walls 204 with a piston 206 positioned therein.
The piston may include a piston ring and/or liner disposed between
an outer wall of the piston and the inner wall of the cylinder. The
piston 206 may be coupled to a crankshaft 208 so that reciprocating
motion of the piston is translated into rotational motion of the
crankshaft. In some embodiments, the engine may be a four-stroke
engine in which each of the cylinders fires (e.g., fuel is injected
into each cylinder) in accordance with a firing order during two
revolutions of the crankshaft. In other embodiments, the engine may
be a two-stroke engine in which each of the cylinders fires in a
firing order during one revolution of the crankshaft.
[0026] The cylinder 200 receives intake air for combustion from an
intake including an intake runner (or manifold) 210. The intake
runner 210 receives intake air via an intake manifold. The intake
runner 210 may be configured such that there is one runner per
cylinder or such that a single intake runner communicates with
multiple cylinders (e.g. one runner per bank of a V-engine which
communicates with all cylinders on a bank, wherein the V-engine
consists of two runners) of the engine in addition to the cylinder,
for example, or the intake runner 210 may communicate exclusively
with that one cylinder.
[0027] Exhaust gas resulting from combustion in the engine is
supplied to an exhaust including an exhaust runner 212. Exhaust gas
flows through the exhaust runner 212, to a turbocharger in some
embodiments (turbocharger not shown in FIG. 2) and to atmosphere,
via an exhaust manifold. The exhaust runner 212 may further receive
exhaust gases from other cylinders of the engine in addition to the
single cylinder (as shown), for example.
[0028] Each cylinder of the engine may include one or more intake
valves and one or more exhaust valves. For example, the cylinder in
FIG. 2 is shown including at least one intake poppet valve 214 and
at least one exhaust poppet valve 216 located in an upper region of
cylinder. In some embodiments, each cylinder of the engine may
include at least two intake poppet valves and at least two exhaust
poppet valves located at the cylinder head.
[0029] The intake valve 214 may be controlled by the controller via
an actuator 218. Similarly, the exhaust valve 216 may be controlled
by the controller via an actuator 220. During some conditions, the
controller may vary the signals provided to the actuators 218 and
220 to control the opening and closing of the respective intake and
exhaust valves. The position of the intake valve 214 and the
exhaust valve 216 may be determined by respective valve position
sensors 222 and 224, respectively. The valve actuators may be of
the electric valve actuation type or cam actuation type, or a
combination thereof, for example.
[0030] The intake and exhaust valve timing may be controlled
concurrently or any of a possibility of variable intake cam timing,
variable exhaust cam timing, dual independent variable cam timing
or fixed cam timing may be used. In other embodiments, the intake
and exhaust valves may be controlled by a common valve actuator or
actuation system, or a variable valve timing actuator or actuation
system. Further, the intake and exhaust valves may by controlled to
have variable lift by the controller based on operating
conditions.
[0031] In some embodiments, each cylinder of the engine may be
configured with one or more fuel injectors for providing fuel
thereto (as shown in FIG. 1). As a non-limiting example, FIG. 2
shows the cylinder including a fuel injector 226. The fuel injector
226 is shown coupled directly to the cylinder for injecting fuel
directly therein. In this manner, fuel injector 226 provides what
is known as direct injection of a fuel into the cylinder. The fuel
may be delivered to the fuel injector 226 from a high-pressure fuel
system including a fuel tank 232, fuel pumps, and a fuel rail (not
shown). In one example, the fuel is diesel fuel that is combusted
in the engine through compression ignition. In other non-limiting
embodiments, the fuel may be gasoline, kerosene, jet fuel, heavy
hydrocarbon oils derived from petroleum crudes, heavy non-petroleum
hydrocarbon oils, heavy biodiesel, or other petroleum distillates
of similar density through compression ignition (and/or spark
ignition). In other embodiments, the fuel may be a combination of
two or more of these different types of fuel. In yet other
embodiments, ignition of the fuel-air mixture is achieved through
the use of laser or plasma ignitors. Further, each cylinder of the
engine may be configured to receive gaseous fuel (e.g., natural
gas) alternative to or in addition to diesel fuel. The gaseous fuel
may be provided to the cylinder via the intake manifold, as
explained below, or other suitable delivery mechanism or mechanisms
such as multi-port injection of gaseous fuel very close to the
intake valve(s) of each cylinder or direct injection of gaseous
fuel in to the engine cylinder.
[0032] Turning to FIG. 3, a method 300 for adjusting fuel injection
of one or more fuel injectors of an engine based on a response in
an engine operating parameter following a fuel injector injection
event is shown. As explained above, at least one fuel injector may
be coupled to each cylinder (such as fuel injectors 111 shown in
FIG. 1 and/or fuel injector 226 shown in FIG. 2). Further, each
fuel injector of each cylinder may fire (e.g., inject fuel) at a
different time in a single engine cycle according to a cylinder
firing order of the engine (e.g., cylinder 1, cylinder 2, cylinder
3 . . . ). Accordingly, after each injection of fuel into a
cylinder, an engine operating parameter may change in response to
the injection. This change in engine operating parameter may be
used to determine a change in performance of one or more of the
fuel injectors from what is expected. Instructions for carrying out
method 300 and the rest of the methods included herein may be
executed by a controller (such as controller 148 shown in FIGS.
1-2) based on instructions stored in the memory of the controller
and in conjunction with signals received from sensors of the engine
system, such as the sensors described above with reference to FIGS.
1-2 (e.g., knock sensors 110 and crankshaft speed sensor 209). The
controller may employ engine actuators of the engine system (such
as actuators of fuel injectors) to adjust engine operation,
according to the methods described below.
[0033] At 302, the method includes estimating and/or measuring
engine operating conditions. Engine operating conditions may
include one or more of engine speed, engine torque output, a knock
level, misfire indication, engine load, mass air flow, engine
temperature, ambient pressure, ambient temperature, peak cylinder
pressure (PCP), indicated mean effective pressure (IMEP), or the
like. At 304, the method includes determining whether it is time
for a fuel injector diagnostic. In one example, a fuel injector
diagnostic may be requested or performed automatically after a
duration of engine operation, a number of engine cycles, a number
of fuel injection events for each fuel injector, and/or a distance
of vehicle travel. In another embodiment, a fuel injector
diagnostic may be performed during each engine cycle. In yet
another embodiment, a fuel injector(s) diagnostic may be performed
either just after engine start-up, or just before engine shut-down,
or both start-up and shut-down. If it is not time to perform the
fuel injector diagnostic, the method continues to 306. At 306, the
method includes injecting fuel via one or more fuel injectors into
each cylinder based on a previous fuel injector diagnostic and
current engine operating conditions. As explained further below,
during a fuel injector diagnostic, the performance of the fuel
injectors may be determined and compared to expected values. If the
fuel injector performance of one or more fuel injectors is
different than expected (but still within the confines of
pre-defined lower limit and upper limit of performance), the
controller may adjust fuel injection (e.g., via adjusting a pulse
width of fuel injected by the fuel injector) to deliver a desired
amount of fuel and account for the change in performance.
[0034] Alternatively, at 304, if it is time for a fuel injector
diagnostic, the method continues to 308 to determine whether to use
a pilot injection for the diagnostic. In one example, as explained
further below, a pilot injection may be performed via a fuel
injector, in addition to and before the primary fuel injection
(e.g., main injection). For example, the primary fuel injection may
inject a larger pulse of fuel during a compression stroke of the
cylinder (e.g., in a four-stroke cycle which includes intake,
compression, combustion, and exhaust strokes) and the pilot
injection may inject a smaller pulse of fuel separate from and
prior to the primary fuel injection during the same cycle of the
same cylinder. In one example, the pilot injection method for
diagnosing fuel injector performance may be used when set operating
conditions for performing the diagnostic are met. In one example,
the set operating conditions may include a selected notch level or
range of notch levels (e.g., notch eight), engine speed within a
threshold range (e.g., between a lower threshold engine speed and
an upper threshold engine speed), and/or an engine power level
within a threshold range (e.g., between a lower threshold power
level and an upper threshold power level).
[0035] If the conditions for diagnosing the fuel injectors via
pilot injection at 308 are not met, the method continues to 320. At
320, the method includes injecting fuel into each cylinder of the
engine and diagnosing the fuel injectors based on a variation in
engine speed acceleration between the engine cylinders. The method
at 320 is expanded upon in method 500 of FIG. 5, as described
further below. Alternatively, at 308, if the conditions for
diagnosing the fuel injectors via pilot injection are met, the
method continues to 310 to select an individual cylinder or group
of cylinders for pilot injection. In one embodiment, only one
cylinder may receive a pilot injection via its fuel injector during
a single engine cycle. For example, during a single engine cycle
including performing a primary injection at each cylinder,
according to the cylinder firing order, only one fuel injector of
one cylinder may additionally perform the pilot injection. In this
way, an engine operating parameter response due to the pilot
injection may be registered and correlated to the one fuel injector
that performed the pilot injection. As such, only one fuel injector
of one cylinder may be diagnosed at a time (e.g., during a single
engine cycle). The method at 310, 312, and 314 may then be repeated
for each fuel injector of each cylinder during different engine
cycles, as explained further below. In another embodiment, more
than one cylinder may receive the pilot injection during a single
engine cycle. However, these cylinders may be adequately and/or
significantly separated from one another in the cylinder firing
order (e.g., they may not be fired sequentially, one after the
other) so that the engine operating parameter response due to each
pilot injection may be correlated to the correct fuel injector or
fuel injectors. In this way, a subset (single or group) of the
engine cylinders may receive the pilot injection during the same
engine cycle but at different times during that engine cycle.
[0036] After selecting the cylinder(s) and corresponding fuel
injector(s) for the pilot injection, the method continues to 312 to
perform the pilot injection at the selected cylinder (or cylinders)
and diagnose the fuel injector(s) according to the method 400
presented at FIG. 4 (as described further below). As explained
further below, in one example, diagnosing the fuel injector may
include determining an effective pulse width of the pilot injection
for achieving a pre-defined engine parameter (such as engine
speed), comparing it to an expected pulse width, and determining
degradation or a change in performance of the fuel injector based
on how the effective pulse width changes over time. Following
performing the pilot injection, the method continues to 314 to
perform the primary fuel injection at the selected cylinder and all
other cylinders of the engine (unless one or more cylinders are
being skip fired). After all firing cylinders have been fired (via
primary fuel injection) during the engine cycle, the method
continues to 316 to determine whether the fuel injector diagnostic
should be repeated for one or more of the other cylinders (and
corresponding fuel injectors). If the diagnostic should be
repeated, the method circles back to 310.
[0037] However, if the diagnostic is not to be repeated for the
other cylinders (e.g., if the diagnostic has already been performed
for all fuel injectors), the method continues to 318 to adjust
subsequent fuel injections (e.g., subsequent primary injections
during the next or following engine cycles for the diagnosed fuel
injectors) based on the results of the diagnosis. For example, the
method at 318 may include adjusting the amount of fuel or pulse
width of fuel injected via the primary injection of a diagnosed
fuel injector based on a determined engine speed, engine torque
output, engine knock, or engine misfire response during the pilot
injection (if continuing from 318) or the engine speed acceleration
response during injecting fuel into each cylinder (if continuing
from 320). For example, the controller may determine a control
signal to send to the fuel injector actuator, such as an updated
primary pulse width of the signal being determined based on a
determination of the engine operating parameter response during the
diagnostic routine. The controller may determine the pulse width
through a determination that directly takes into account a
determined effective pulse width (as described further below with
regard to method 400) or a determined engine speed acceleration (as
described further below with regard to method 500), such as
decreasing the primary effective pulse width or decreasing engine
speed acceleration. The controller may alternatively determine the
pulse width based on a calculation using a look-up table with the
input being the effective pulse width, engine operating parameter
response to the pilot injection, and/or the engine speed
acceleration, and the output being the new or updated or commanded
pulse-width.
[0038] In one embodiment of method 300, each of the methods at 312
and 320 may additionally include controlling a turbocharger (such
as turbocharger 120 shown in FIG. 1) and/or an amount of intake air
entering the engine cylinders to a steady-state level. For example,
this may include operating the turbocharger at a steady (and not
changing) boost level. In another example, this may include
maintaining a position of an air throttle in the intake passage at
a set position. As a result, the air-fuel ratio entering the engine
cylinders may not change during the testing (e.g., diagnosing)
period due to the airflow.
[0039] FIG. 4 shows a method 400 for diagnosing a condition of a
fuel injector based on a response in an engine operating parameter
following performing a pilot injection with the fuel injector.
Method 400 may continue from the method at 312 in FIG. 3. As such,
method 400 begins at 402 by injecting a first pulse of fuel as a
pilot injection into the selected cylinder(s). For example, the
method at 402 may include injecting the first pulse of fuel via a
first fuel injector coupled to the selected cylinder. In one
example, the method at 402 may also include determining an amount
or pulse width of the first pulse. The amount or pulse width of the
first pulse of fuel may be smaller than a second pulse of fuel
injected during the primary injection event of the first fuel
injector (e.g., the primary injection being a main injection
occurring separate from and after the pilot injection, as explained
above). In another example, the amount or pulse width of the first
pulse of fuel may be selected based on an amount of fuel that will
cause a detectable change in an engine operating parameter (for
diagnosing the fuel injector). For example, the first pulse of fuel
must be large enough so that an engine speed sensor may detect a
change in engine speed from a baseline engine speed after
performing the pilot injection. After performing the pilot
injection at 402, the method continues to 404.
[0040] At 404, the method includes correlating a response in an
engine operating parameter to the pilot injection. As explained
above, after injecting the first pulse of fuel as the pilot
injection via the first fuel injector, an engine operating
parameter may change due to (e.g., in response to) the pilot
injection. This change from baseline of the engine operating
parameter may then be correlated with the pilot injection. As one
example, the engine operating parameter may be engine speed and the
response in the engine operating parameter may be an increase
(e.g., spike) in engine speed from a baseline engine speed (prior
to the pilot injection) to engine speed after the pilot injection.
As another example, the engine operating parameter may be the
engine torque output measured via a torque sensor coupled to the
engine crankshaft. The measured torque level may register the
actual combustion noise due to the pilot injection. As one example,
the response in the engine operating parameter may be the change in
the torque level determined from the torque sensor output. In yet
another example, the engine operating parameter may be a misfire
level or indication determined from an output of the torque sensor.
As another example, the engine operating parameter may be a knock
level output via a knock sensor coupled to the cylinder that the
first fuel injector is coupled to. The knock level may register the
actual combustion noise due to the pilot injection. As one example,
the response in the engine operating parameter may be the change in
the IMEP or PCP determined from the knock sensor output. In yet
another example, the engine operating parameter may be a misfire
level or indication determined from an output of the knock
sensor.
[0041] At 406, the method includes determining the effective pulse
width of the pilot injection of the fuel injector of the selected
cylinder(s) based on the response in the engine operating parameter
determined at 404. In one example, determining the effective pulse
width may include the controller making a logical determination of
the effective pulse width of the pilot injection based on logic
rules that are a function of the engine operating parameter (e.g.,
engine speed, engine torque output, engine knock, IMEP, PCP, and/or
engine misfire). As one example, the controller may receive the
engine speed signal from the engine speed sensor before, during,
and after the pilot injection, determine the change in the engine
speed signal from the baseline engine speed due to the pilot
injection, and determine (e.g., calculate as a function of the
change in engine speed or use a look-up table with the input being
the change in engine speed due to the pilot injection) the
effective pulse width of the pilot injection. In another example,
the controller may compare the knock signature received from the
knock sensor following the pilot injection to a reference knock
sensor signature and then determine the effective pulse width. For
example, the controller may determine the effective pulse width as
a function of the measured knock signature following the pilot
injection and the reference knock signature.
[0042] At 408, the method includes injecting a second pulse of fuel
as a primary injection into the selected cylinder(s) and adjusting
the primary injection based on the determined effective "primary"
pulse width. For example, the controller may compare the determined
effective pulse width to the commanded pulse width for the first
amount of fuel of the pilot injection. If the effective pulse width
was larger than commanded, then too much fuel may have been
injected via the first injector. Alternatively, if the effective
pulse width was smaller than commanded, then too little fuel may
have been injected via the first injector. As a result, the
controller may compensate for this difference by adjusting the
primary injection amount (e.g., increase if the effective pilot
pulse width was too small and decrease if the effective pilot pulse
width was too large). Specifically, the controller may make a
logical determination of the pulse width of the second pulse of
fuel for the primary injection of the selected cylinder based on
logic rules that are a function of the determined effective pilot
pulse width. In this way, the controller may correct/adjust
subsequent fuel injections with the injector of the selected
cylinder to account for degradation, aging, or faults of the fuel
injector or fuel injector components (e.g., nozzle fuel spray
holes, solenoids, or the like).
[0043] At 410, the method includes monitoring (e.g., tracking) the
effective pulse width of the fuel injector over time. For example,
for each pilot injection event (during the injector diagnostic) of
a single fuel injector, the controller may determine the effective
pulse width and track changes to the effective pilot pulse width
over time and over a number of pilot injections. For example, FIG.
6 shows a graph 600 of example changes to an effective pulse width
of a fuel injector over time and a number of pilot injection
events. Specifically, graph 600 shows a first plot 602 of a
baseline effective pulse width that does not change significantly
(e.g., greater than a threshold amount of change) over time. Graph
600 also shows a second plot 604 where the effective pulse width
increases over time and a third plot 606 where the effective pulse
width decreases over time. At time t1, the effective pulse width of
the second plot 604 and the third plot 606 begin changing and at
time t2 the effective pulse widths of these two plots may change by
an amount that exceeds the threshold amount of change. As a result,
the controller may indicate degradation or a change in performance
of the fuel injector, as explained further below.
[0044] Returning to FIG. 4, at 412 the method includes determining
if the effective pulse width is increasing (e.g., as shown at plot
604 in FIG. 6). In one example, the controller may determine the
effective pulse width is increasing if a rate of change of the
effective pulse width is greater than a threshold rate of change.
In another example, the controller may determine the effective
pulse width is increasing if the most recent effective pulse width
value is a threshold amount different than a previous effective
pulse width value or an original effective pulse width value (e.g.,
the effective pulse width when the injector was new or used for the
very first time for a pilot injection). If the effective pulse
width is increasing, the method continues to 414 to indicate a
change in performance of the fuel injector. As one example, the
method at 414 may include indicating one or more of a decrease in
response time of a solenoid of the fuel injector and/or a clogged
or degraded fuel injector. In one example, the controller may send
a notification (e.g., audible or visual) to a vehicle operator that
the fuel injector needs to be serviced or replaced. Alternatively,
at 412, if the effective pilot pulse width is not increasing, the
method continues to 416 to determine if the effective pilot pulse
width is decreasing (similar to as explained above for 412). If the
effective pulse width is decreasing, the method continues to 418 to
indicate one or more of an increase in a size of one or more nozzle
fuel spray holes of the fuel injector and/or a faulty
injector/injection. The controller may then send an indication to
the vehicle operator, as described above. If the effective pilot
pulse width is not increasing and/or not decreasing, the method
instead continues to 420 to not indicate degradation of the fuel
injector and to continue (normally) injecting fuel with the fuel
injector.
[0045] Method 400 may be repeated for each cylinder (and fuel
injector coupled to each cylinder) during different engine cycles.
An example of performing pilot injections via two fuel injectors of
two different cylinders during different engine cycles is shown in
FIG. 7. Specifically, FIG. 7 shows a graph 700 showing fuel
injection events at a first cylinder at plot 702, fuel injection
events at a second cylinder at plot 704, fuel injection events at a
third cylinder at plot 706, and changes in engine speed at plot
708. In the example shown in FIG. 4, the cylinder firing order may
be cylinder 1-cylinder 2-cylinder 3. Prior to time t1, the
controller may determine that it is time to perform a diagnostic of
a first fuel injector coupled to the first cylinder. As such, at
time t1, the first fuel injector injects a first pulse of fuel as a
pilot injection into the first cylinder (plot 702). In response to
injecting the first pulse of fuel, engine speed increases from the
baseline value prior to the pilot injection (plot 708). During the
pilot injection, no other cylinders are receiving fuel injections
(e.g., no other fuel injectors are firing). At time t2, a duration
after time t1, the controller actuates the first fuel injector to
inject a second pulse of fuel as the primary injection into the
first cylinder (plot 702). Since the engine speed response
following the pilot injection may be smaller than expected for the
commanded first pulse of fuel, the controller may increase the
second pulse of fuel above a previously commanded amount (e.g., the
amount of fuel injection for the primary injection at the first
cylinder is larger than for the other cylinders in the firing
order). In response to the injecting of the second "primary" pulse
of fuel, engine speed increases. The increase in engine speed due
to the primary injection is larger than the increase in engine
speed due to the pilot injection since the second pulse of fuel is
greater than the first pulse of fuel (as denoted by the height of
the arrows in plot 702). The next cylinder in the firing order,
cylinder 2, receives its primary injection of fuel via a second
fuel injector at time t3 and then cylinder 3 receives its primary
injection of fuel via a third fuel injector at time t4.
[0046] After time t4, the controller may determine that it is time
to perform a diagnostic of the second fuel injector coupled to the
second cylinder. As shown at time t5, the first fuel injector again
injects fuel, but only as a primary injection, into the first
cylinder. Additionally, the amount of fuel injected during the
primary injection at time t5 is greater than the amount of fuel
injected during the primary injections at the other cylinders. The
second injector then injects a smaller, first pulse of fuel (at
time t6) as the pilot injection into the second cylinder and then,
at time t7, a larger, second pulse of fuel as the primary injection
into the second cylinder. During the pilot injection into the
second cylinder, no other fuel injectors of the other cylinders are
injecting fuel. Finally, the third cylinder receives the primary
injection of fuel from the third fuel injector at time t8. In this
way, a pilot injection of fuel may be used to diagnose fuel
injectors of different engine cylinders during different engine
cycles. As a result, engine speed responses may be correlated to
the pilot injection for the single cylinder receiving the pilot
injection and then used to diagnose the performance of the fuel
injector.
[0047] Turning to FIG. 5, a method 500 for diagnosing a condition
of one or more fuel injectors based on a variation in engine speed
accelerations after injecting fuel into each cylinder is shown.
Method 500 may continue from the method at 320 in FIG. 3. As such,
method 500 begins at 502 by injecting fuel into each cylinder over
a single engine cycle. For example, every cylinder may receive a
primary injection of fuel, at its time in the firing order, via the
fuel injector coupled thereto. As a result, every fuel injector may
fire once in the single engine cycle. At 504, the method includes
determining individual engine speed accelerations resulting from
the injection of fuel into each cylinder. For example, as shown in
FIG. 7, every time fuel is injected into a cylinder, engine speed
may increase (and accordingly the acceleration of the engine speed
increases proportional to injected fuel quantity). The controller
may receive the engine speed signal from an engine speed sensor
during all the injection events and then correlate each engine
speed acceleration (e.g., each peak in engine speed) to each fuel
injector/cylinder based on the known firing order of the cylinders.
As a result, the controller may make a logical determination of the
individual engine speed accelerations for each fuel
injector/cylinder based on logic rules that are a function of the
received (e.g., measured) engine speed signal and the known firing
order.
[0048] At 506, the method includes comparing the individual engine
speed acceleration values for each fuel injector/cylinder and
determining the variation in engine speed accelerations between the
cylinders. In one example, a same amount of fuel may be injected
into each cylinder via each corresponding fuel injector at 502. In
another example, different amounts of fuel may be injected into
each cylinder (e.g., due to variations in
aging/deterioration/degradation of performance or characteristics
of the fuel injectors). However, in both examples, approximately
the same engine speed acceleration response may be expected due to
fuel injection at each cylinder. In one example, determining the
variation in the engine speed accelerations between the cylinders
may include the controller calculating a standard deviation between
the determined individual engine speed accelerations corresponding
to each cylinder (e.g., each fuel injection event at each
cylinder). At 508, the method includes determining whether the
variation determined at 506 is greater than a threshold level. In
one example, the threshold level may be a level that indicates a
change in performance or degradation of one or more of the fuel
injectors relative to the remaining fuel injectors. In one example,
the allowable variation in fueling quantity (injection
event-to-injection event or injector-to-injector) is within +1-1.5%
of nominal quantity when the injector is new. In this example, the
allowable variation on threshold prior to condemning an in-use
injector and/or changing to a new injector is +/-3% or higher of
nominal quantity.
[0049] If the determined variation is not greater than the
threshold level, the method continues to 510 to not indicate
degradation of the fuel injectors and to instead continue injecting
fuel via the fuel injectors based on engine operating conditions.
Alternatively, at 508, if the variation is greater than the
threshold level, the method continues to 512 to indicate
degradation of one or more of the fuel injectors and then identify
which fuel injector (or injectors) is degraded based on the
individual engine speed acceleration and the known engine cylinder
firing order. For example, the controller may know the crankshaft
position (e.g., angle) at which each individual engine speed
acceleration occurred (from an output of a crankshaft position or
speed sensor). By comparing this to the known firing order and a
known crank angle at which each fuel injector of each cylinder
fires, the controller may determine which individual engine speed
acceleration belongs to which specific cylinder (and the
corresponding fuel injector). The controller may then determine
which engine speed acceleration deviated from the other engine
speed accelerations (or an average value of all of the engine speed
accelerations) and then indicate degradation of the corresponding
fuel injector (e.g., the fuel injector that injected fuel which
corresponds to engine speed acceleration that varied the greatest
amount or a threshold amount from the average).
[0050] At 514, the method includes determining if the identified
engine speed acceleration resulting from injection via the
indicated fuel injector is greater than an expected engine speed
acceleration. In one example, the expected engine speed
acceleration may be an average engine speed acceleration of all the
engine cylinders. In another example, the expected engine speed
acceleration may be determined from a look-up table with the
commanded fuel injection amount (or pulse width) as the input and
the expected engine speed acceleration as the output. If the engine
speed acceleration of the indicated fuel injector is greater than
the expected engine speed acceleration, the method continues to 516
to indicate injection error and/or an increase in a size of one or
more nozzle holes of the injector (e.g., since this may mean too
much fuel was injected via the identified fuel injector). In one
example, the indication/action at 516 may include the controller
sending an audible or visual indication to the vehicle operator
that the fuel injector needs to be serviced or replaced.
Alternatively, at 514, if the engine speed acceleration of the
indicated fuel injector is not greater than (e.g., is less than)
the expected engine speed acceleration, the method continues to 518
to indicate one or more of a clogged fuel injector, mechanical
degradation of the fuel injector, and/or degradation of a solenoid
of the fuel injector.
[0051] In this way, the technical effect of diagnosing a condition
or indicating degradation of one or more fuel injectors of the
engine is identifying a degraded or malfunctioning injector before
more serious degradation of the engine or ceasing of functioning of
the injector occurs. Further, by identifying which injector is
experiencing a change in performance (as determined by correlating
a change in response in an engine operating parameter following a
pilot injection into one engine cylinder or a comparison of primary
injections of fuel into all engine cylinders), the controller may
take corrective action to compensate for the change in performance.
For example, the controller may adjust fuel injection to account
for a changing effective pulse width of one or more of the
injectors. By identifying which injector is degraded, only the
degraded injector may be serviced or replaced (and not every single
fuel injector). This may reduce repair and/or replacement costs.
Further, if fuel injectors continue to be functional past their
specified lifetime, they may continue to be used, rather than
automatically replaced at a pre-defined usage period (such as A
months or B mega-watt hours), thereby saving additional part
costs.
[0052] As one embodiment, a method for an engine comprises
injecting a first pulse of fuel as a first pilot injection into a
first subset of cylinders of a plurality of engine cylinders, where
the first pilot injection precedes a primary injection of fuel into
the first subset of cylinders by a duration; correlating a first
response in an engine operating parameter to the first pilot
injection; and adjusting the primary injection of fuel into the
first subset of cylinders based on the first response. In one
example, the first subset of cylinders includes a single cylinder,
injecting the first pulse of fuel includes injecting the first
pulse of fuel as the first pilot injection into only the single
cylinder via a first fuel injector, and the method further
comprises diagnosing a condition of the first fuel injector based
on a change in the first response over a number of first pilot
injections. The method may further comprise estimating an effective
pulse width of the first fuel injector based on the first response
for the number of first pilot injections and diagnosing the
condition of the first fuel injector based on a change in the
estimated effective pulse width over the number of first pilot
injections. In one example, diagnosing the condition of the first
fuel injector includes indicating an increase in a size of one or
more nozzle fuel spray holes of the first fuel injector in response
to the estimated effective pilot pulse width decreasing over the
number of first pilot injections. In another example, diagnosing
the condition of the first fuel injector includes indicating one or
more of a decrease in response time of a solenoid of the first fuel
injector or mechanical degradation of the first fuel injector in
response to the estimated effective pulse width increasing over the
number of first pilot injections. For example, the
adjustment/correction may include the effective pilot pulse width
being increased over the number of first pilot injections.
Alternately, the response may include an increase in the rise-rate
of the pilot pulse. In one example, the method may further
comprise, at a different time during engine operation than
injecting the first pulse of fuel, injecting a second pulse of fuel
as a second pilot injection into a second subset of cylinders of
the plurality of engine cylinders via one or more fuel injectors,
where the second pilot injection precedes a primary injection of
fuel into the second subset of cylinders by a pre-defined duration.
The method may further comprise correlating a second response in
the engine operating parameter to the second pilot injection,
adjusting the primary injection of fuel into the second subset of
cylinders based on the second response, and diagnosing the one or
more fuel injectors based on a change in the second response over a
number of second pilot injections. Further, in one example, the
first pilot injection and the second pilot injection occur during
different engine cycles where a primary injection of fuel is
injected into each cylinder of the plurality of engine cylinders.
In another example, the engine operating parameter is one of a
knock level output by a knock sensor coupled to the first subset of
cylinders, an engine speed output by an engine speed sensor coupled
to a crankshaft of the engine, or an engine torque output measured
by an engine torque sensor coupled to the crankshaft of the engine.
The method may further comprise delivering the first pilot
injection and the primary injection of fuel into the first subset
of cylinders via one or more fuel injectors and adjusting the
primary injection of fuel into the first subset of cylinders based
on the first response may include determining an effective pulse
width of the first pilot pulse of fuel based on the first response
and adjusting a pulse width of the primary injection of fuel
delivered by the one or more fuel injectors based on the determined
effective pulse width. The method may further comprise injecting a
second pulse of fuel as the primary injection of fuel into the
first subset of cylinders, where the first pulse of fuel is smaller
than the second pulse of fuel and where the first pulse of fuel and
the second pulse of fuel are separated from one another by a
pre-set spacing in time or crank angle. In another example, the
method may further comprise injecting the first pulse of fuel as
the first pilot injection into the first subset of cylinders in
response to the engine operating at a selected notch level and at
an engine speed within a threshold engine speed range. In still
another example, injecting the first pulse of fuel as the first
pilot injection occurs during a first engine cycle where a primary
injection of fuel is injected into each cylinder of the plurality
of engine cylinders and the first pilot injection of the first
pulse of fuel is only injected into the first subset of cylinders,
the method may further comprise, during a different, second engine
cycle, not injecting the first pulse of fuel as the first pilot
injection into the first subset of cylinders and injecting a second
pulse of fuel as the primary injection into the first subset of
cylinders, and where during the second engine cycle, the second
pulse of fuel is larger than during the first engine cycle. In one
example, the second pulse of fuel is larger than during the first
engine cycle because 100% of the energy to power the engine and
maintain engine speed and engine torque, is achieved via this
single pulse versus a combination of the first pilot fuel pulse and
the second primary fuel pulse.
[0053] As another embodiment, a method for an engine comprises
injecting fuel into each cylinder of a plurality of cylinders of
the engine over a single engine cycle via a plurality of fuel
injectors, where each fuel injector of the plurality of fuel
injectors is coupled to a different cylinder of the plurality of
cylinders; determining individual engine speed accelerations
resulting from the injection of fuel into each cylinder; and
indicating degradation of one or more of the plurality of fuel
injectors in response to a variation in the determined individual
engine speed accelerations being greater than a threshold
acceleration level. In one example, the method may further comprise
indicating which fuel injector of the plurality of fuel injectors
is degraded based on the individual engine speed accelerations and
a known engine cylinder firing order of the engine. In another
example, indicating degradation includes: indicating an increase in
a size of one or more nozzle fuel spray holes of the indicated fuel
injector in response to the individual engine speed acceleration
resulting from the injection of fuel via the indicated fuel
injector being greater than an expected engine speed acceleration
for a non-degraded fuel injector; and indicating one or more of a
decrease in response time of a solenoid of the indicated fuel
injector or mechanical degradation of the indicated fuel injector
in response to the individual engine speed acceleration resulting
from the injection of fuel via the indicated fuel injector being
less than the expected engine speed acceleration.
[0054] As yet another embodiment, a system for an engine comprises
a plurality of engine cylinders including at least a first cylinder
and a second cylinder; a first fuel injector coupled to the first
cylinder; a second fuel injector coupled to the second cylinder;
and a controller with computer readable instructions for: during a
first engine cycle, injecting a primary pulse of fuel into the
first cylinder via the first fuel injector and the second cylinder
via the second fuel injector and injecting a pilot pulse of fuel,
before the primary pulse, into only the first cylinder via the
first fuel injector; correlating a first response in an engine
operating parameter to injection of the pilot pulse of fuel into
the first cylinder; and during a second engine cycle, following the
first engine cycle, adjusting the primary pulse of fuel into the
first cylinder based on the first response to the pilot pulse of
fuel. In one example, the computer readable instructions further
include instructions for: during a third engine cycle, injecting
the primary pulse of fuel into the first cylinder via the first
fuel injector and the second cylinder via the second fuel injector
and injecting the pilot pulse of fuel, before the primary pulse,
into only the second cylinder via the second fuel injector;
correlating a second response in the engine operating parameter to
injection of the pilot pulse of fuel; and during a fourth engine
cycle, following the third engine cycle, adjusting the primary
pulse of fuel into the second cylinder based on the second response
to the pilot pulse of fuel. In another example, the system may
further comprise a real-time engine torque output sensor coupled to
a crankshaft of the engine, where the engine operating parameter is
a torque signal output by the torque output sensor, and where the
computer readable instructions further include instructions for
diagnosing a condition of the first injector in response to a
change in the torque output over a number of engine cycles when the
pilot pulse of fuel is injected into the first cylinder via the
first fuel injector. In yet another example, the system may further
comprise a knock sensor coupled to the first cylinder, where the
engine operating parameter is a knock signal output by the knock
sensor, and where the computer readable instructions further
include instructions for diagnosing a condition of the first
injector in response to a change in the knock signal over a number
of engine cycles when the pilot pulse of fuel is injected into the
first cylinder via the first fuel injector.
[0055] As used herein, an element or step recited in the singular
and proceeded with the word "a" or "an" should be understood as not
excluding plural of said elements or steps, unless such exclusion
is explicitly stated. Furthermore, references to "one embodiment"
of the invention do not exclude the existence of additional
embodiments that also incorporate the recited features. Moreover,
unless explicitly stated to the contrary, embodiments "comprising,"
"including," or "having" an element or a plurality of elements
having a particular property may include additional such elements
not having that property. The terms "including" and "in which" are
used as the plain-language equivalents of the respective terms
"comprising" and "wherein." Moreover, the terms "first," "second,"
and "third," etc. are used merely as labels, and are not intended
to impose numerical requirements or a particular positional order
on their objects.
[0056] The control methods and routines disclosed herein may be
stored as executable instructions in non-transitory memory and may
be carried out by the control system including the controller in
combination with the various sensors, actuators, and other engine
hardware. The specific routines described herein may represent one
or more of any number of processing strategies such as
event-driven, interrupt-driven, multi-tasking, multi-threading, and
the like. As such, various actions, operations, and/or functions
illustrated may be performed in the sequence illustrated, in
parallel, or in some cases omitted. Likewise, the order of
processing is not necessarily required to achieve the features and
advantages of the example embodiments described herein, but is
provided for ease of illustration and description. One or more of
the illustrated actions, operations and/or functions may be
repeatedly performed depending on the particular strategy being
used. Further, the described actions, operations and/or functions
may graphically represent code to be programmed into non-transitory
memory of the computer readable storage medium in the engine
control system, where the described actions are carried out by
executing the instructions in a system including the various engine
hardware components in combination with the electronic
controller.
[0057] 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.
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