U.S. patent application number 10/024428 was filed with the patent office on 2003-06-19 for automated electronic trim for a fuel injector.
Invention is credited to Rodier, William J..
Application Number | 20030111043 10/024428 |
Document ID | / |
Family ID | 21820536 |
Filed Date | 2003-06-19 |
United States Patent
Application |
20030111043 |
Kind Code |
A1 |
Rodier, William J. |
June 19, 2003 |
AUTOMATED ELECTRONIC TRIM FOR A FUEL INJECTOR
Abstract
A method and apparatus for trimming a fuel injector that
delivers multiple injections or injection segments per engine cycle
is provided. Trimming a fuel injector comprises determining a first
fuel quantity to be delivered by the plurality of injectors,
partially suspending fuel delivery by one selected injector,
determining a second fuel quantity, and determining a fuel
characteristic of the selected injector in response to the first
and second fuel quantities.
Inventors: |
Rodier, William J.;
(Metamora, IL) |
Correspondence
Address: |
CATERPILLAR INC.
100 N.E. ADAMS STREET
PATENT DEPT.
PEORIA
IL
616296490
|
Family ID: |
21820536 |
Appl. No.: |
10/024428 |
Filed: |
December 18, 2001 |
Current U.S.
Class: |
123/299 |
Current CPC
Class: |
F02D 41/402 20130101;
F02D 41/403 20130101; Y02T 10/44 20130101; F02D 41/2432 20130101;
F02D 41/3005 20130101; F02D 2200/0602 20130101; F02D 2200/023
20130101; F02D 41/008 20130101; F02M 45/02 20130101; Y02T 10/40
20130101; F02D 41/2467 20130101; F02D 41/2438 20130101; F02D 41/405
20130101; F02M 57/025 20130101 |
Class at
Publication: |
123/299 |
International
Class: |
F02B 003/00 |
Claims
What is claimed is:
1. A method of trimming a fuel injector comprising the steps of:
determining a first fuel quantity to be delivered by a plurality of
fuel injectors; delivering fuel injection signals to said plurality
of fuel injectors to deliver said first fuel quantity wherein at
least one of said plurality of injectors receives multiple
injection segment signals per engine cycle; partially suspending
fuel delivery by one of said plurality of injectors receiving
multiple injection segment signals by suspending at least one of
said multiple injections segment signals; determining a second fuel
quantity to be delivered by said plurality of injectors in response
to said suspending step; determining a performance characteristic
of said partially suspended injector in response to said first and
said second fuel quantities.
2. The method of claim 1 wherein delivering multiple injection
segment signal includes delivering a pilot injection signal.
3. The method of claim 1 wherein delivering multiple injection
segment signal includes delivering a post injection signal.
4. The method of claim 1 wherein delivering multiple injection
segment signal includes delivering an anchor injection signal.
5. The method of claim 1 wherein the step of determining said
performance characteristic of said partially suspended injector
further comprises: comparing said first and said second fuel
quantities; and determining a fuel offset to be applied to said
partially suspended injector in response to said comparison.
6. The method of claim 5 further comprising applying said fuel
offset to said suspended multiple injection signal.
7. The method of claim 1 wherein the step of determining said
performance characteristic of said partially suspended injector
further comprises: comparing said first and said second fuel
quantities; and determining a fuel quantity delivered by said
suspended multiple injection signal of said partially suspended
injector in response to said comparing step.
8. The method of claim 1 further comprising: determining an engine
speed related to said first fuel quantity; adjusting said first
fuel quantity to said second fuel quantity in order to maintain
said engine speed after said suspending step; comparing said first
fuel quantity and said second fuel quantity; determining a fuel
offset for said partially suspended injector in response to said
comparing step.
9. The method of claim 1 further comprising activating fully said
partially suspended injector.
10. A method of trimming fuel injectors within a system, comprising
a plurality of fuel injectors, comprising the steps of: injecting
in a first mode wherein each injector of said plurality of
injectors injects a first predetermined quantity of fuel;
determining a first predetermined total quantity of fuel injected
by said plurality of injectors; selecting one injector from said
plurality of injectors and injecting in a second mode, wherein a
specific second quantity of fuel is less than said specific first
quantity of fuel; determining a second total quantity of fuel
injected by said plurality of injectors in response to said
selecting step; and determining a performance characteristic of
said selected injector in response to said first and said second
total quantities of fuel.
11. The method of claim 10 wherein said first mode includes
injecting with at least two injections per engine cycle.
12. The method of claim 10 wherein said second mode includes
injecting with at least one less injection per engine cycle than
said first mode.
13. The method of claim 10 wherein the step of determining a
performance characteristic of said selected injector further
comprises the steps of: comparing said first and said second total
quantities of fuel; and determining a fuel offset to be applied to
said selected injector in response to said comparing step.
14. The method of claim 10 wherein the step of determining a
performance characteristic of said selected injector further
comprises the steps of: comparing said first and said second total
quantities of fuel; and determining a fuel quantity delivered by
said selected injector in response to said comparing step.
15. The method of claim 10 further comprising the steps of:
determining an engine speed related to said first total quantity of
fuel; adjusting said first total fuel quantity to said second total
fuel quantity in order to maintain said engine speed after said
selecting step; comparing said first total fuel quantity to said
second total fuel quantity; and determining a fuel offset for said
selected injector.
16. A system for trimming a fuel injector comprising: a plurality
of fuel injectors; an engine performance sensor adapted to measure
an engine performance characteristic; and a controller adapted to
receive a signal from said engine performance sensor, send multiple
injection signals to each of said plurality of fuel injectors,
determine a first fuel quantity injected by said plurality of
injectors, suspend at least one of said multiple injection signals
to partially suspend fuel delivery of one of said plurality of
injectors, adjust said first fuel quantity to a second fuel
quantity in order to maintain said engine performance
characteristic at a relatively constant level, determine said
second fuel quantity injected by said plurality of injectors;
compare said first and said second fuel quantities, and determine a
performance characteristic of said partially suspended
injector.
17. The system of claim 16 wherein said engine performance
characteristic is engine speed.
Description
TECHNICAL FIELD
[0001] The present invention is directed to a fuel control system
and specifically to a method and apparatus for trimming a multiple
injection fuel injector.
BACKGROUND
[0002] Emissions continue to drive fuel injector design and
performance. As emissions standards continue to increase it becomes
ever more important to control the fuel injector and the quantity
of fuel being injected with great precision; however, precise
control of injectors is difficult because manufacturing variation
and wear can make each injector operate slightly different. In
other words, although two injectors may receive the same injection
signal, they may inject different amounts of fuel. This can then
change expected combustion performance and generate more emissions
than desired.
[0003] One method to overcome injector to injector variation has
been to trim individual injectors. In one method of trimming, an
injector's performance profile is determined after assembly and
prior to installation in an engine. The performance profile is then
provided to the engine's electronic control module (ECM), which
takes that performance profile in to account when sending signals
to the injector. The problem with this type of trimming is that it
does not account for wear variations after the injector has been in
use for a period of time. In another method of trimming, disclosed
in U.S. Pat. No. 6,189,378 B1, to Kendrick et al., an injector can
be trimmed in an engine by using a cylinder cut out method. In this
method, one injector is shut off completely during engine
operation, and its fuel delivery is determined by examining what
the other injectors needed to do to compensate for the loss of the
one injector. Although this exemplary method of trimming provides
good results, injection schemes have become more complicated.
Specifically, injectors are now injecting several times during an
engine cycle and it is necessary to trim each injection event but
the cylinder cut out method completely suspends the injector and
therefore, individual injection events by the injector can not be
distinguished.
[0004] The present invention is directed to overcoming one or more
of the problems set forth above.
SUMMARY OF THE INVENTION
[0005] In one embodiment of the present invention, a method of
trimming a fuel injector comprises the steps of determining a first
fuel quantity to be delivered by a plurality of fuel injectors,
delivering fuel injection signals to the plurality of injectors
delivering a first fuel quantity wherein at least one of the
plurality of injectors receives multiple injection segment signals
per engine cycle, partially suspending fuel delivery by one of the
plurality of injectors receiving multiple injection segment signals
by suspending at least one of the multiple injection segment
signals, determining the second fuel quantity to be delivered by
the plurality of injectors in response to the suspending step, and
determining a performance characteristic of the partially suspended
injector in response to the first and second fuel quantities.
[0006] In the second embodiment of the present invention, a method
of trimming fuel injectors comprises the steps of: injecting in a
first mode wherein each injector receives a specific first quantity
of fuel, determining a first total quantity of fuel injected by the
plurality of injectors, selecting one injector from the plurality
of injectors and injecting in the second mode, wherein the specific
second quantity of fuel is less than the specific first quantity of
fuel, determining a second total quantity of fuel injected by the
plurality of injectors in response to the selected step, and
determining a performance characteristic of said selected injector
in response to the first total quantity and second total quantity
of fuel.
[0007] In a third embodiment of the present invention, a system for
trimming a fuel injector comprises a plurality of fuel injectors,
an engine performance center adapted to measure an engine
performance characteristic, and a controller adapted to receive a
signal from the performance sensor, send multiple injection signals
to the plurality of fuel injectors, determine the first fuel
quantity injected by the plurality of injectors, suspend at least
one of the multiple injection signals to partially suspend fuel
delivery by one of a plurality of injectors, adjust the first fuel
quantity to a second fuel quantity in order to maintain an engine
performance characteristic at a relatively constant level,
determine the second fuel quantity injected by the plurality of
injectors, compare the first and second fuel quantities and
determine a performance characteristic of the partially suspended
injector.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic of a fuel injection system.
DETAILED DESCRIPTION
[0009] Referring to FIG. 1, there is shown an embodiment of a
hydraulically-actuated electronically-controlled fuel injection
system 110 in an example configuration as adapted for a
direct-injection diesel-cycle internal combustion engine 112. Fuel
system 110 includes one or more hydraulically-actuated
electronically-controlled fuel injectors 114, positioned in a
respective cylinder head bore (not shown) of engine 112. Fuel
system 110 includes a first source of pressurized fluid flow 116
for supply of actuating fluid to each injector 114, a second source
of pressurized fluid flow 118 for supplying fuel to each injector,
a computer 120 for electronically controlling the fuel injection
system and an apparatus 122 for re-circulating actuation fluid
leaving each of the injectors.
[0010] The first fluid source 116 preferably includes an actuating
fluid sump 124, a relatively low pressure actuating fluid transfer
pump 126, an actuating fluid cooler 128, one or more actuation
fluid filters 130, a high pressure pump 132 for generating
relatively high pressure in the actuation fluid and at least one
relatively high pressure actuation fluid manifold 136. A common
rail passage 138 is arranged in fluid communication with the outlet
from the relatively high pressure actuation fluid pump 132. A rail
branch passage 140 connects the actuation fluid inlet of each
injector 114 to the high pressure common rail passage 138.
[0011] Actuation fluid leaving an actuation fluid drain of each
injector 114 enters a re-circulation line 127 that carries the same
to the actuation fluid re-circulating apparatus 122. A portion of
the re-circulated actuation fluid is channeled to high pressure
actuation fluid pump 132 and another portion is returned to
actuation fluid sump 124 via re-circulation line 133.
[0012] In a preferred embodiment, the actuation fluid is engine
lubricating oil and the actuation fluid sump 124 is an engine
lubrication oil sump. This allows the fuel injection system to be
connected as a parasitic subsystem to the engine's lubricating oil
circulation system.
[0013] The second fluid source 118 preferably includes a fuel tank
142, a fuel supply passage 144 arranged in fluid communication
between fuel tank 142 and the fuel inlet of each injector 114, a
relatively low pressure fuel transfer pump 146, one or more fuel
filters 148, a fuel supply regulating valve 149, and a fuel
circulation and return passage 147 arranged in fluid communication
between injectors 114 and fuel tank 142.
[0014] The computer 120 preferably includes an electronic control
module (ECM) 111 including a microprocessor and memory. As is known
to those skilled in the art, the memory is connected to the
microprocessor and stores an instruction set and variables.
Associated with the microprocessor and part of the electronic
control module 111 are various other known circuits such as power
supply circuitry, signal conditioning circuitry and solenoid driver
circuitry, among others. The electronic control module 111 controls
1) the fuel injection timing; 2) the total fuel injection quantity
during an injection cycle; 3) the fuel injection pressure; 4) the
number of separate injections or injection segments during each
injection cycle; 5) the time intervals between the injection
segments; 6) the fuel quantity of each injection segment during an
injection cycle; 7) the actuation fluid pressure; 8) current level
of the injector waveform; and 9) any combination of the above
parameters. Computer 120 receives a plurality of sensor input
signals S1-S8, which correspond to known sensor inputs, such as
engine operating conditions including engine speed, engine
temperature, pressure of the actuation fluid, load on the engine,
etc., as well as desired operating conditions such as desired
engine speed, that are used to determine the precise combination of
injection parameters for a subsequent injection cycle.
[0015] For example, an engine temperature sensor 180 is shown
connected to the engine 112. In one embodiment, the engine
temperature sensor includes an engine oil temperature sensor.
However, an engine coolant temperature sensor can also be used to
detect the engine temperature. The engine temperature sensor
produces a signal designated by S1 in FIG. 1 and is input to the
computer 120 over line S1. Another example of an engine sensor
input is a rail pressure sensor 185 shown connected to the high
pressure common rail passage 138 for producing a high pressure
signal S2 responsive to the pressure of the actuating fluid. The
electronic control module 111 inputs the high pressure signal on
input S2.
[0016] In this example, computer 120 issues control signal S9 to
control the actuation fluid pressure and a fuel injection signal
S10 to energize a solenoid within a fuel injector thereby
controlling fluid control valve(s) within each injector 114 and
causing fuel to be injected into a corresponding engine cylinder.
Each of the injection parameters are variably controllable,
independent of engine speed and load. In the case of injector 114,
control signal S10 is a fuel injection signal that is a computer
commanded current to the injector solenoid.
[0017] Fuel injectors 114 are capable of multiple injections or
injection segments per engine cycle. As stated previously, the ECM
111 controls when, duration and number of injections or segments
for each injector 114 per engine cycle. Multiple injections or
injection segments are well know in the art and may include pilots,
mains, posts, and anchors.
[0018] In order to obtain desired engine performance and emissions,
it is necessary to understand how the injector 114 is operating and
adjust or trim the injector's 114 operation as necessary. The
problem of trimming an injector has been complicated due to the
numerous injections or segments that may occur per engine cycle.
Each injection segment needs to be trimmed; therefore a complete
cylinder cut out approach will not work because it is not possible
to differentiate between injection segments. In one embodiment of
the present invention, each injection segment can be trimmed
individually while the injectors are operating in the engine.
[0019] In order to trim each injection segment, it is first
necessary to determine the total quantity of fuel being injected by
the injectors 114. This is simply done by summing the quantity of
fuel from all injection segments for each injector 114. Once the
total quantity of fuel is know, the ECM 111 picks an engine
characteristic, preferably engine speed, to remain constant. The
ECM 111 then selects one injector 114 and partially suspends fuel
delivery. This is done by suspending one of injection segments,
such as the pilot or post. Partially suspending injection will then
impact engine performance. The ECM 111 then proceeds to alter the
injection profile for the remaining injectors 114 in order to
maintain constant engine performance. For example, the ECM 111 may
increase fuel delivery to the remaining injectors to compensate for
the lost fuel from the partially suspended injector in order to
maintain engine speed.
[0020] The ECM 111 then determines what the new fuel quantity is
and from this, the ECM 111 can determine the amount of fuel that
was being injected by the selected injector 114 until fuel delivery
was partially suspended. This can be done by comparing the first
total fuel quantity to the second total fuel quantity and
understanding the relationship between the quantity of fuel
injected, the injection profile, and specific engine performance.
Once the ECM 111 knows the amount of fuel that was injected by the
suspended injection segment, it can then compare that quantity of
fuel with what was expected to be delivered based upon the ECM's
111 injection signal S10. If a difference exists, the ECM 111 can
then adjust or trim the injection signal S10 appropriately.
INDUSTRIAL APPLICABILITY
[0021] Initially, ECM 111 sends an injection signal S10 to
injectors 114. This signal may include multiple injections or
injection segments for each injector per engine cycle. The initial
injection signals S10 sent to each injector 114 are designed to
inject a desired quantity of fuel. Due to manufacturing variation
and injector wear, the exact amount of fuel injected may differ
from the desired amount. In order to enhance engine performance and
reduce emissions, the fuel injector 114 needs to be trimmed--the
injection signal S10 needs to be altered for each specific injector
to compensate for variations from injector to injector and
injection segment to injection segment.
[0022] In order to trim a fuel injector, the ECM 111 must first
determine the total quantity of fuel being injected for a given
operational load. The ECM 111 then partially suspends injection by
selecting one injector 114 and suspending an injection segment for
that injector 114. The suspended injection segment could be any
segment, including the pilot, main, post, or anchor. After
suspending the selected injection segment, the ECM 111 monitors
engine performance and compensates for the lost quantity of fuel
injected by altering the injection profile of the remaining
injectors 114 in order to maintain the operational load. For
example, the ECM 111 can monitor engine speed through one of its
sensors S1-8. An initial engine speed is determined prior to
partially suspending and injector 114. After suspending an
injection segment on a selected injector 114, the ECM maintains
that engine speed by increasing the fuel quantity injected by the
remaining injectors.
[0023] The ECM 114 then compares the first fuel quantity to the new
fuel quantity to determine the amount of fuel injected by the
suspended injection segment. This is done based upon the
relationship of quantity of fuel injected, injection profiles, and
engine performance. The ECM 111 then computes the actual fuel
injected by the suspended injection segment to the desired quantity
of fuel. If the quantities are not equal, the ECM 111 knows that
the selected injector 114 is operating differently than expected
and takes this in to account the next time it sends an injection
signal S10 to the injector 114. For example if it was learned that
the injection segment of the selected injector was injecting less
fuel than desired, the ECM 111 could change the duration of
injection signal S10 sent to the injector 114, for that injection
segment, to increase the quantity of fuel injected.
[0024] The trimming method disclosed can be applied in a variety of
manners. First, each injection segment can be independently
trimmed. Second, various engine loads can be used. For example, the
trimming could be done at idle, or could be performed with an
engine at load. In order to have an engine at load, the vehicle
would need to be moving, use an engine component, such as a engine
compression release brake to place a load on the vehicle, or use a
chassis dyno or cell dyno if the injectors are not in a vehicle.
Further, the description provided described hydraulically actuated,
electronically controlled fuel injectors; however, the trimming
methods described would be equally applicable to other types of
fuel systems and injectors, including common rail and mechanically
actuated injectors. Finally, the present specification talks about
injector operation and suspending injections. It is also possible
to view the injectors in the present application as injecting in
different modes. The injector injects in a first mode when all of
the injections are occurring and injects in a second mode when one
of the injection segments is eliminated or the quantity of fuel
injected in altered.
[0025] Other aspects, features, and advantages of the present
invention may be obtained from a study of this disclosure and the
drawings, along with the appended claims.
LIST OF ELEMENTS
[0026] TITLE: Automated Electronic Trim for a Fuel Injector
[0027] FILE: 01-211
[0028] 110 fuel injection system
[0029] 111 electronic control module
[0030] 112 internal combustion engine
[0031] 114 fuel injectors
[0032] 116 means for supplying actuator fluid
[0033] 118 means for supplying fuel
[0034] 120 computer
[0035] 122 means for re-circulating actuation fluid
[0036] 124 actuating fluid sump
[0037] 126 actuating fluid transfer pump
[0038] 127 re-circulation line
[0039] 128 actuating fluid cooler
[0040] 130 actuating fluid filter
[0041] 132 high pressure pump
[0042] 133 re-circulation line
[0043] 136 actuation fluid manifold
[0044] 138 common rail passage
[0045] 140 rail branch passage
[0046] 142 fuel tank
[0047] 144 fuel supply passage
[0048] 146 transfer pump
[0049] 147 return passage
[0050] 148 fuel filter
[0051] 149 regulating valve
[0052] 180 engine temperature sensor
[0053] 185 rail pressure sensor
* * * * *