U.S. patent application number 10/670589 was filed with the patent office on 2005-03-31 for system and method for controlling fan activation based on intake manifold air temperature and time in an egr system.
This patent application is currently assigned to DETROIT DIESEL CORPORATION. Invention is credited to Avery, Richard Michael JR., Super, Leopold.
Application Number | 20050066914 10/670589 |
Document ID | / |
Family ID | 33418839 |
Filed Date | 2005-03-31 |
United States Patent
Application |
20050066914 |
Kind Code |
A1 |
Avery, Richard Michael JR. ;
et al. |
March 31, 2005 |
SYSTEM AND METHOD FOR CONTROLLING FAN ACTIVATION BASED ON INTAKE
MANIFOLD AIR TEMPERATURE AND TIME IN AN EGR SYSTEM
Abstract
A method for controlling at least one engine cooling fan for a
compression ignition internal combustion, the method includes
turning on the at least one cooling fan when an intake manifold air
temperature is equal to or greater than a predetermined turn-on
threshold temperature for a predetermined turn-on time, and turning
off the at least one cooling fan when the intake manifold air
temperature is equal to or less than a predetermined turn-off
threshold temperature for a predetermined turn-off time, wherein
the predetermined turn-on threshold temperature is greater than the
predetermined turn-off threshold temperature.
Inventors: |
Avery, Richard Michael JR.;
(West Bloomfield, MI) ; Super, Leopold; (Dearborn,
MI) |
Correspondence
Address: |
BROOKS KUSHMAN P.C.
1000 TOWN CENTER
TWENTY-SECOND FLOOR
SOUTHFIELD
MI
48075
US
|
Assignee: |
DETROIT DIESEL CORPORATION
13400 Outer Driver, West
Detroit
MI
48239-4001
|
Family ID: |
33418839 |
Appl. No.: |
10/670589 |
Filed: |
September 25, 2003 |
Current U.S.
Class: |
123/41.12 |
Current CPC
Class: |
F01P 7/048 20130101;
F01P 2025/62 20130101; F01P 2025/42 20130101; F01P 2005/025
20130101 |
Class at
Publication: |
123/041.12 |
International
Class: |
F01P 007/02 |
Claims
1. A method for controlling at least one engine cooling fan for a
compression ignition internal combustion engine, the method
comprising: turning on the at least one cooling fan when an intake
manifold air temperature is equal to or greater than a
predetermined turn-on threshold temperature for a predetermined
turn-on time; and turning off the at least one cooling fan when the
intake manifold air temperature is equal to or less than a
predetermined turn-off threshold temperature for a predetermined
turn-off time, wherein the predetermined turn-on threshold
temperature is greater than the predetermined turn-off threshold
temperature.
2. The method of claim 1 further comprising determining the
predetermined turn-on time and the predetermined turn-off time via
a look up table and in response to the intake manifold air
temperature.
3. The method of claim 1 further comprising turning off the at
least one cooling fan when an engine coolant temperature is below a
predetermined temperature.
4. The method of claim 3 further comprising turning off the at
least one cooling fan when both of the intake manifold air
temperature and the engine coolant temperature are equal to or less
than respective predetermined temperatures when the intake manifold
air and engine coolant temperatures are independent of one
another.
5. The method of claim 1 further comprising turning on the at least
one cooling fan when a final torque generated by the engine is
equal to or greater than a predetermined value.
6. The method of claim 1 further comprising delaying turn-on of the
at least one fan when the engine is attempting to start or within 5
seconds after starting.
7. The method of claim 1 further comprising determining the
predetermined turn-on time and the predetermined turn-off time
using a counter.
8. The method of claim 1 further comprising turning on the at least
one fan when there is a fault in at least one sensor related to
determination of the intake manifold air temperature.
9. The method of claim 1 further comprising: turning on a low speed
one of the at least one fans when the air inlet temperature is
equal to or greater than a predetermined low turn-on threshold
temperature for a predetermined low turn-on time; turning off the
low speed fan when the intake manifold air temperature is equal to
or less than a predetermined low turn-off threshold temperature for
a predetermined low turn-off time, wherein the predetermined low
turn-on threshold temperature is greater than the predetermined low
turn-off threshold temperature; turning on a high speed one of the
at least one fans when the air inlet temperature is equal to or
greater than a predetermined high turn-on threshold temperature for
a predetermined high turn-on time; and turning off the high speed
fan when the intake manifold air temperature is equal to or less
than a predetermined high turn-off threshold temperature for a
predetermined high turn-off time, wherein the predetermined high
turn-on threshold temperature is greater than the predetermined
high turn-off threshold temperature and the predetermined high
turn-on threshold temperature is greater than the predetermined low
turn-on threshold temperature.
10. The method of claim 9 further comprising transitioning off the
high speed fan when the intake manifold air temperature is equal to
or less than the predetermined high turn-off threshold temperature
plus a low offset value for the predetermined high turn-off
time.
11. A system for controlling at least one cooling fan for a
compression ignition internal combustion engine, the system
comprising: at least one sensor for providing an indication of at
least one engine component parameter; and an engine controller in
communication with the at least one engine component parameter
sensor, the engine controller configured to, turn on the at least
one cooling fan when an intake manifold air temperature is equal to
or greater than a predetermined turn-on threshold temperature for a
predetermined turn-on time; and turn off the at least one cooling
fan when the intake manifold air temperature is equal to or less
than a predetermined turn-off threshold temperature for a
predetermined turn-off time, wherein the predetermined turn-on
threshold temperature is greater than the predetermined turn-off
threshold temperature.
12. The system of claim 11 wherein the controller is further
configured to determine the predetermined turn-on time and the
predetermined turn-off time via a look up table and in response to
the intake manifold air temperature.
13. The system of claim 11 wherein the controller is further
configured to turn off the at least one cooling fan when an engine
coolant temperature is below a predetermined temperature.
14. The system of claim 13 wherein the controller is further
configured to turn off the at least one cooling fan when both of
the intake manifold air temperature and the engine coolant
temperature are equal to or less than respective predetermined
temperatures when the intake manifold air and engine coolant
temperatures are independent of one another.
15. The system of claim 14 wherein the controller is further
configured to turning on the at least one cooling fan when a final
torque generated by the engine is equal to or greater than a
predetermined value.
16. The system of claim 11 wherein the controller is further
configured to delay turning on the at least one fan when the engine
is attempting to start or within 5 seconds after starting.
17. The system of claim 11 wherein the controller is further
configured to determine the predetermined turn-on time and the
predetermined turn-off time using a counter.
18. The system of claim 11 wherein the controller is further
configured to turn on the at least one fan when there is a fault in
at least one sensor related to determination of the intake manifold
air temperature.
19. The system of claim 11 wherein the controller is further
configured to: turn on a low speed one of the at least one fans
when the air inlet temperature is equal to or greater than a
predetermined low turn-on threshold temperature for a predetermined
low turn-on time; turn off the low speed fan when the intake
manifold air temperature is equal to or less than a predetermined
low turn-off threshold temperature for a predetermined low turn-off
time, wherein the predetermined low turn-on threshold temperature
is greater than the predetermined low turn-off threshold
temperature; turn on a high speed one of the at least one fans when
the air inlet temperature is equal to or greater than a
predetermined high turn-on threshold temperature for a
predetermined high turn-on time; and turn off the high speed fan
when the intake manifold air temperature is equal to or less than a
predetermined high turn-off threshold temperature for a
predetermined high turn-off time, wherein the predetermined high
turn-on threshold temperature is greater than the predetermined
high turn-off threshold temperature and the predetermined high
turn-on threshold temperature is greater than the predetermined low
turn-on threshold temperature.
20. The system of claim 11 wherein the controller is further
configured to transition off the high speed fan when the intake
manifold air temperature is equal to or less than the predetermined
high turn-off threshold temperature plus a low offset value for the
predetermined high turn-off time.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a system and a method for
controlling engine cooling fan activation based on intake manifold
air temperature and time in an exhaust gas recirculation (EGR)
system.
[0003] 2. Background Art
[0004] Internal combustion engines, and in particular, compression
ignition (or diesel) engines have a wide variety of applications
including passenger vehicles, marine vessels, earth-moving and
construction equipment, stationary generators, and on-highway
trucks, among others. However, due to the loads carried by the
vehicles and the size of the machinery that utilize internal
combustion engines, internal combustion engines (e.g., diesel
engines) generate a great deal of heat during operation.
[0005] The heat generated by internal combustion engines has also
increased due to the addition of exhaust gas recirculation (EGR)
systems into the engines. EGR systems recirculate exhaust into the
intake air stream of the engine, thereby reducing oxides of
nitrogen that are formed when temperatures in the combustion
chamber of the engine get too hot. Although the EGR systems help to
reduce exhaust emissions that cause smog, EGR systems cause the
intake manifold air temperatures of the engine to increase.
[0006] Some conventional systems and methods for controlling the
heat within internal combustion engines implement a fixed speed, a
variable speed, or multiple engine cooling fans that move air over
a radiator where engine coolant flows and is cooled by the air
movement. A conventional electronic control unit operates the fan
in accordance with received fan request signals, turning the fan on
or off and adjusting the fan speed depending on the temperature
within the engine (e.g., in response to engine coolant
temperature). However, some of the fan requests are unnecessary due
to short increases in temperature caused by quick changes in engine
load (e.g., small rolling hills, idle to rapid acceleration
operation, intermittent workpiece characteristics for power takeoff
driven applications, etc.). The unnecessary fan requests can cause
the engine speed and output torque to fluctuate erratically. The
engine speed and torque fluctuations can cause undesirable vehicle
(or machinery) speed variations, noise and vibration, reduced fuel
economy, etc.
[0007] Thus, there exists a need and an opportunity for an improved
system and an improved method for engine cooling fan control. The
present invention may implement an improved system and an improved
method for controlling cooling fan activation and fan speed based
on intake manifold air temperature and time in an EGR system. The
present invention may minimize the unnecessary fan request signals
as sent by some conventional approaches and, thus, may provide
improved efficiency and noise control for operation of the fan
activation system. Furthermore, the present invention may provide
more flexible fan control parameters (i.e., a greater number of
modes of engine cooling fan control) when compared to conventional
approaches.
SUMMARY OF THE INVENTION
[0008] The present invention generally provides new, improved and
innovative techniques for controlling engine cooling fan activation
based on intake manifold temperature and time in an exhaust gas
recirculation system. The improved system and method for engine fan
control of the present invention may minimize unnecessary fan
request signals as sent by some conventional approaches and may
provide improved efficiency and noise control for operation of the
fan activation system. Furthermore, the present invention may
provide more flexible fan control parameters (i.e., a greater
number of modes of engine cooling fan control) when compared to
conventional approaches.
[0009] According to the present invention, a method for controlling
at least one engine cooling fan for a compression ignition internal
combustion is provided. The method comprises turning on the at
least one cooling fan when an intake manifold air temperature is
equal to or greater than a predetermined turn-on threshold
temperature for a predetermined turn-on time, and turning off the
at least one cooling fan when the intake manifold air temperature
is equal to or less than a predetermined turn-off threshold
temperature for a predetermined turn-off time, wherein the
predetermined turn-on threshold temperature is greater than the
predetermined turn-off threshold temperature.
[0010] Also according to the present invention, a system for
controlling at least one cooling fan for a compression ignition
internal combustion engine is provided. The system comprises at
least one sensor for providing an indication of at least one engine
component parameter and an engine controller in communication with
the at least one engine component parameter sensor. The engine
controller may be configured to turn on the at least one cooling
fan when an intake manifold air temperature is equal to or greater
than a predetermined turn-on threshold temperature for a
predetermined turn-on time, and turn off the at least one cooling
fan when the intake manifold air temperature is equal to or less
than a predetermined turn-off threshold temperature for a
predetermined turn-off time, wherein the predetermined turn-on
threshold temperature is greater than the predetermined turn-off
threshold temperature.
[0011] The above features, and other features and advantages of the
present invention are readily apparent from the following detailed
descriptions thereof when taken in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a diagram illustrating a compression ignition
engine incorporating various features of the present invention;
[0013] FIGS. 2(a-c) are diagrams illustrating a system for engine
cooling fan control according to the present invention;
[0014] FIG. 3 is a state diagram of an engine cooling fan mode of
operation according to the present invention; and
[0015] FIG. 4 is a state diagram of another engine cooling fan mode
of operation according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0016] With reference to the Figures, the preferred embodiments of
the present invention will now be described in detail. Generally,
the present invention provides an improved system and an improved
method for engine cooling fan control.
[0017] The present invention is generally implemented in connection
with an internal combustion engine (e.g., a compression ignition or
diesel engine) having an exhaust gas recirculation (EGR) system.
Since EGR systems recirculate exhaust gas into the intake air
stream of the engine, EGR systems generally cause the intake
manifold temperatures of the engine to increase. Intake air
temperature generally increases when the EGR is actuated. As such,
EGR activation time (i.e., "time in EGR") and intake manifold air
temperature are generally directly related (or directly
corresponding).
[0018] To control or optimize at least one mode of the engine
(e.g., an internal combustion engine in general and a compression
ignition engine in particular) operation and engine cooling fan
operation where the respective operations are generally controlled
by an electronic control module (ECM)/powertrain control module
(PCM) or controller, the engine controller should be adaptable
(i.e., programmable, modifiable, configurable, etc.) to a variety
of input signals or parameters. However, conventional electronic
engine controllers have a limited set of parameters that are used
(i.e., monitored) by the controller to adjust (i.e., control) the
engine operation and engine cooling fan operation.
[0019] Conventional approaches to control of engine cooling fan
operation are generally limited to monitoring parameters such as
engine coolant temperature (i.e., engine operating temperature),
engine rotational speed, transmission retarder operational state,
climate control operation, engine oil temperature, hydraulic oil
sump temperature, transmission sump oil temperature, and intake
manifold air (or inlet air) temperature, and to turning the engine
cooling fan on or off, or varying the fan speed. In contrast, the
system and method of the present invention in at least one mode of
operation, generally activate a fan "on" request signal when the
intake manifold air temperature has been at or above a first
predetermined level for at least a first predetermined time (or,
alternatively, the EGR has been activated for a first predetermined
time). Similarly, the fan "on" signal may be presented until the
intake manifold air temperature has been below a second
predetermined level for a second predetermined time (or,
alternatively, the EGR has been de-activated for a second
predetermined time).
[0020] Referring to FIG. 1, a perspective view illustrating a
compression-ignition internal combustion engine 10 incorporating
various features according to the present invention is shown. The
engine 10 may be implemented in a wide variety of applications
including on-highway trucks, construction equipment, marine
vessels, stationary generators, pumping stations, and the like. The
engine 10 generally includes a plurality of cylinders disposed
below a corresponding cover, indicated generally by reference
numeral 12.
[0021] In a preferred embodiment, the engine 10 is a multi-cylinder
compression ignition internal combustion engine, such as a 3, 4, 6,
8, 12, 16, or 24 cylinder diesel engine. However, the engine 10 may
be implemented having any appropriate number of cylinders 12, the
cylinders having any appropriate displacement and compression ratio
to meet the design criteria of a particular application. Moreover,
the present invention is not limited to a particular type of engine
or fuel. The present invention may be implemented in connection
with any appropriate engine (e.g., Otto cycle, Rankine cycle,
Miller cycle, etc.) using an appropriate fuel to meet the design
criteria of a particular application. An EGR valve 13 is generally
connected between an exhaust manifold 14 and an intake manifold 15.
The EGR valve 13 generally provides recirculation of a portion of
exhaust gas in response to at least one predetermined engine 10
operating condition (i.e., a time in EGR).
[0022] The engine 10 generally includes an engine control module
(ECM), powertrain control module (PCM), or other appropriate
controller 32 (described in detail in connection with FIG. 2a). The
ECM 32 generally communicates with various engine sensors and
actuators via associated interconnection cabling or wires 18, to
control the engine 10 and at least one engine cooling fan. In
addition, the ECM 32 generally communicates with an engine operator
or user (not shown) using associated lights, switches, displays,
and the like (not shown).
[0023] In one example, the engine 10 may be mounted (i.e.,
installed, implemented, positioned, disposed, etc.) in a vehicle
(not shown). In another example, the engine 10 may be installed in
a stationary environment. The engine 10 may be coupled to a
transmission (not shown) via flywheel 16. Many transmissions
include a power take-off (PTO) configuration where an auxiliary
shaft (not shown) may be connected to associated auxiliary
equipment (not shown). Cooling for the engine 10 is generally
provided by at least one cooling fan 20 (described in connection
with FIGS. 2b and 2c). The at least one cooling fan 20 may be
positioned and configured to provide air movement over a radiator
(not shown) where engine coolant is circulated and cooled by the
air movement.
[0024] The auxiliary equipment may be driven by the engine
10/transmission at a relatively constant rotational speed using an
engine variable speed governor (VSG) feature. The auxiliary
equipment may include hydraulic pumps for construction equipment,
water pumps for fire engines, power generators, and any of a number
of other rotationally driven accessories. Typically, when the PTO
apparatus is installed on a vehicle, the PTO mode is generally used
while the vehicle is stationary. However, the present invention is
independent of the particular operation mode of the engine 10, or
whether the vehicle is stationary or moving for the applications in
which the engine 10 is used in a vehicle having a PTO mode.
[0025] Referring to FIGS. 2(a-c), diagrams illustrating a system 30
for controlling an engine and for controlling at least one engine
cooling fan, or for controlling an engine cooling fan according to
the present invention are shown. The system 30 may be implemented
in connection with the engine 10 of FIG. 1. As illustrated in FIG.
2a, the system 30 preferably includes the controller (e.g., ECM,
PCM, and the like) 32 in communication with various sensors 34 and
actuators 36. The sensors 34 may include various position sensors
such as an accelerator or brake position sensor 38. Likewise, the
sensors 34 may include a coolant temperature sensor 40 that
generally provides an indication of the temperature of an engine
block 42 and an intake manifold air temperature sensor that
generally provides an indication of the temperature of the engine
intake air at the inlet or within the intake manifold. Likewise, an
oil pressure sensor 44 may be used to monitor the engine 10
operating conditions by providing an appropriate signal to the
controller 32. Other sensors (not shown) may include at least one
sensor that indicates actuation of an EGR control valve (not
shown), at least one sensor that indicates actuation of the at
least one cooling fans 20, and at least one sensor that indicates
rotational speed of the at least one cooling fans 20.
[0026] Other sensors may include rotational sensors to detect the
rotational speed of the engine 10, such as RPM sensor 88 and a
vehicle speed sensor (VSS) 90 in some applications. The VSS 90
generally provides an indication of the rotational speed of the
output shaft or tailshaft (not shown) of the transmission. The
speed of the shaft monitored via the VSS 90 may be used to
calculate the vehicle speed. The VSS 90 may also represent one or
more wheel speed sensors which may be used in anti-lock breaking
system (ABS) applications, vehicle stability control systems, and
the like.
[0027] The actuators 36 may include various engine components which
are operated via associated control signals from the controller 32.
The various actuators 36 may also provide signal feedback to the
controller 32 relative to the actuator 36 operational state, in
addition to feedback position or other signals used to the control
actuators 36. The actuators 36 preferably include a plurality of
fuel injectors 46 which are controlled via associated (or
respective) solenoids 64 to deliver fuel to the corresponding
cylinders 12. The actuators 36 may include at least one actuator
that may be implemented to control the at least one cooling fan
20.
[0028] In one embodiment, the controller 32 controls a fuel pump 56
to transfer fuel from a source 58 to a common rail or manifold 60.
However, in another example, the present invention may be
implemented in connection with a direct injection engine. Operation
of the solenoids 64 generally controls delivery of the timing and
duration of fuel injection (i.e., an amount, timing and duration of
fuel). While the representative control system 30 illustrates an
example application environment of the present invention, as noted
previously the present invention is not limited to any particular
type of fuel or fueling system and thus may be implemented in any
appropriate engine and/or engine system to meet the design criteria
of a particular application.
[0029] The sensors 34 and the actuators 36 may be used to
communicate status and control information to the engine operator
via a console 48. The console 48 may include various switches 50
and 54 in addition to indicators 52. The console 48 is preferably
positioned in close proximity to the engine operator, such as in a
cab (i.e., passenger compartment, cabin, etc.) of the vehicle (or
environment) where the system 30 is implemented. The indicators 52
may include any of a number of audio and visual indicators such as
lights, displays, buzzers, alarms, and the like. Preferably, one or
more switches, such as the switch 50 and the switch 54, may be used
to request at least one particular operating mode, such as climate
control (e.g., air conditioning), cruise control or PTO mode, for
example.
[0030] As used throughout the description of the present invention,
at least one selectable (i.e., programmable, predetermined,
modifiable, etc.) limit (i.e., threshold, level, interval, value,
amount, duration, etc.) or range of values may be selected by any
of a number of individuals (i.e., users, operators, owners,
drivers, etc.) via a programming device, such as device 66
selectively connected via an appropriate plug or connector 68 to
the controller 32. Rather than being primarily controlled by
software, the selectable or programmable limit (or range) may also
be provided by an appropriate hardware circuit having various
switches, dials, and the like. Alternatively, the selectable or
programmable limit may also be changed using a combination of
software and hardware without departing from the spirit of the
present invention. However, the at least one selectable value or
range may be predetermined and/or modified by any appropriate
apparatus and method to meet the design criteria of a particular
application. Any appropriate number and type of sensors,
indicators, actuators, etc. may be implemented to meet the design
criteria of a particular application.
[0031] In one embodiment, the controller 32 generally includes a
programmable microprocessing unit 70 in communication with the
various sensors 34 and the actuators 36 via at least one
input/output port 72. The input/output ports 72 may provide an
interface in terms of processing circuitry to condition the
signals, protect the controller 32, and provide appropriate signal
levels depending on the particular input or output device. The
processor 70 generally communicates with the input/output ports 72
using a data/address bus arrangement 74. Likewise, the processor 70
generally communicates with various types of computer-readable
storage media 76 which may include a keep-alive memory (KAM) 78, a
read-only memory (ROM) 80, a random-access memory (RAM) 82, and at
least one timer (or a counter configured as a timer) 84.
[0032] The various types of computer-readable storage media 76
generally provide short-term and long-term storage of data (e.g.,
at least one lookup table, LUT, at least one operation control
routine, etc.) used by the controller 32 to control the engine 10
and the cooling fan 20. The computer-readable storage media 76 may
be implemented by any of a number of known physical devices capable
of storing data representing instructions executable by the
microprocessor 70. Such devices may include PROM, EPROM, EEPROM,
flash memory, and the like in addition to various magnetic,
optical, and combination media capable of temporary and/or
permanent data storage.
[0033] The computer-readable storage media 76 may include data
representing program instructions (e.g., software), calibrations,
routines, steps, methods, blocks, operations, operating variables,
and the like used in connection with associated hardware to control
the various systems and subsystems of the engine 10, the cooling
fan 20, and the vehicle. The engine/vehicle/cooling fan control
logic is generally implemented via the controller 32 based on the
data stored in the computer-readable storage media 76 in addition
to various other electric and electronic circuits (i.e., hardware,
firmware, etc.).
[0034] In one example, the controller 32 includes control logic to
control at least one mode of operation of the engine 10 and at
least one mode of operation of the fan 20. In another example, the
controller 32 may be implemented as a fan controller and engine
control may be performed via another controller (not shown). Modes
of engine 10 operation that may be controlled include engine idle,
PTO operation, engine shutdown, maximum permitted vehicle speed,
maximum permitted engine speed (i.e., maximum engine RPM), whether
the engine 10 may be started (i.e., engine start enable/disable),
engine operation parameters that affect engine emissions (e.g.,
timing, amount and duration of fuel injection, exhaust air pump
operation, etc.), cruise control enable/disable, seasonal
shutdowns, calibration modifications, and the like.
[0035] The modes of operation of the at least one fan 20 are
described below in connection with FIGS. 2(a-c), 3 and 4. In
general, the fan 20 may be configured to turn on for at least one
of excessive air temperature (i.e., intake or inlet air temperature
at or above a predetermined value) and excessive engine coolant
temperature (i.e., engine coolant temperature at or above a
predetermined value). As used throughout the present application,
the phrases air temperature or air inlet temperature may indicate
at least one of intake manifold 15 air temperature, intake manifold
15 inlet air temperature, and time in EGR for the EGR 13.
[0036] The at least one timer 84 is generally configured to
determine (i.e., calculate, count, etc.) at least one predetermined
time interval (e.g., an interval having at least one corresponding
control signal (e.g., FAN_AIR_TEMP_OFF_TIME (or FATOFT), and
FAN_AIR_TEMP_ON_TIME (or FATONT)). The predetermined time intervals
that correspond to the signals FATOFT and FATONT are generally
determined via values in the LUT 76. The controller 32 may present
(e.g., send, transmit, etc.) at least one fan 20 actuator control
signal (e.g., FAN_ON, FAN_LOW_ON, and FAN_HIGH_ON) in response to
at least one sensor 36 signal and at least one predetermined time
(e.g., COUNT_LOW and COUNT_HIGH) determined by the timer 84 in
response to at least one timer control signal (e.g., COUNT_ON,
COUNT_OFF, COUNT_LOW_ON, COUNT_HIGH_ON, COUNT_LOW_OFF, and
COUNT_HIGH_OFF).
[0037] In one example, the interval FATOFT may be a time to
establish or determine a fan "off" point (or level) based on air
temperature (e.g., intake manifold air temperature, inlet air
temperature, etc., or alternatively, a time duration when the EGR
13 is not activated). In another example, for dual speed fan (or
two-fan) 20 configurations the interval FATOFT may be a time to
provide (i.e., establish, determine, etc.) a high speed (or normal
speed) to low fan speed transition (e.g., a temperature axis
positively offset by a value FAN_AIR_LOW_SPEED_OFF_DELTA- ). A
transition may be implemented as a gradual turn on or turn off of
the fan 20 over the respective time corresponding to the signals
FATONT and FATOFT.
[0038] In one example, the interval FATONT may be a time provide
(i.e., establish, determine, etc.) a fan "on" air temperature
(e.g., intake manifold air temperature, inlet air temperature,
etc., or alternatively, a time duration when the EGR 13 is
activated) point (i.e., value, level, etc.) based on air
temperature. In another example, for dual speed fan (or two-speed
fan) 20 configurations the interval FATONT may be a time to
establish or determine an off to low fan speed transition (e.g., a
temperature axis negatively offset by a value
FAN_AIR_LOW_SPEED_ON_DELTA)- .
[0039] The signal FAN_ON may be implemented as a control signal
that may be presented to the actuator 36 to enable the fan 20 to
turn "on." In a two-speed fan implementation, the signal FAN_LOW_ON
may be implemented as a control signal that may be presented to the
actuator 36 to enable the fan 20 to turn "on" at a low speed and
the signal FAN_HIGH_ON may be implemented as a control signal that
may be presented to the actuator 36 to enable the fan 20 to turn
"on" at a high (or normal) speed (i.e., a speed that is higher than
the low speed by at least a predetermined amount). In dual fan
implementation, the signal FAN_LOW_ON may be implemented as a
control signal that may be presented to the actuator 36 to enable a
low speed fan 20 to turn "on" at a respective low speed and the
signal FAN_HIGH_ON may be implemented as a control signal that may
be presented to the actuator 36 to enable a high (or normal) speed
fan 20 to turn "on" at a respective high speed (i.e., a speed that
is higher than the low speed by at least a predetermined amount).
An number of signals (e.g., FAN_OFF, FAN_LOW_OFF, and FAN_HIGH_OFF)
generally correspond to turning off the fan 20, the low speed fan
20, and the high speed fan 20, respectively.
[0040] As described in detail in connection with FIGS. 2(a-c), 3
and 4, the system 30 may have a number of states (e.g., FAN_ON,
FAN_OFF, FAN_LOW_ON, FAN_LOW_OFF, FAN_HIGH_ON, FAN_HIGH_OFF,
COUNT_LOW, COUNT_HIGH, COUNT_ON, COUNT_OFF, COUNT_LOW_ON,
COUNT_HIGH_ON, COUNT_LOW_OFF, and COUNT_HIGH_OFF). The states of
the system 30 (i.e., states that correspond to control signals that
are presented by the controller 32) may be operational states of
the at least one fan 20 and the at least one timer (or counter)
84.
[0041] A variable (or parameter) (e.g., AIR_TEMP_FAN_OFF (or
ATOFF)) may be a predetermined air temperature (e.g., an inlet air
temperature, an intake manifold air temperature, etc.) that
corresponds to a request (or signal) to turn off at least one fan
20. A variable (or parameter) (e.g., AIR_TEMP_FAN1_ON (or AFT1ON))
may be a predetermined air temperature that corresponds to request
(or signal) to turn on at least one normal speed or high speed fan
20. A variable (or parameter) (e.g., AIR_TEMP_FAN2_ON (or AFT2ON))
may be a predetermined air temperature that corresponds to a
request (or signal) to turn on at least one low speed fan 20. The
signals AFT1ON and AFT2ON are generally implemented in connection
with two-speed fan or dual fan applications of the present
invention. The temperature that corresponds to the high speed (or
normal speed) fan on signal AFT1ON is generally a higher
temperature than the temperature that corresponds to the low speed
fan on signal AFT2ON.
[0042] A control signal (e.g., FAN_AIR_DELAY_ENABLE (or FADENB))
may enable (i.e., turn on) logic in the controller 32 to provide
fan 20 on/off time air temperature dependency (in contrast to
methods using "hard" or fixed temperature thresholds) when set
(i.e., "on", enabled, asserted, presented, transmitted, at a logic
TRUE, HIGH or "1" state or level, etc.). In one example, the signal
FADENB may correspond to a time that is equal to the amount of time
the engine 10 is cranking for starting plus 5 seconds. However, the
signal FADENB may correspond to any appropriate time to meet the
design criteria of a particular application. A control signal
(e.g., FAN_AIR_LOW_SPEED_OFF_DELTA (or FALOFD)) may correspond to a
positive offset (or hysteresis) to the FATOFT temperature axis for
a high speed fan 20 to low speed fan 20 operation transition.
[0043] A control signal (e.g., FAN_AIR_LOW_SPEED_ON_DELTA (or
FALOND)) may correspond to a negative offset (or hysteresis) to the
FATONT temperature axis for an "off" to a low speed fan 20
operation transition. A control signal (e.g.,
FAN_AIR_OFF_DELAY_THRESH (or FADOFT)) may correspond to a
temperature threshold (or hysteresis) that may be used by
controller 32 logic to provide a time delay when requesting (or
signaling) at least one fan 20 "off" mode. A control signal (e.g.,
FAN_AIR_ON_DELAY_THRESH (or FADONT)) may correspond to a
temperature threshold (or hysteresis) that may be used by
controller 32 logic to provide a time delay when requesting (or
signaling) at least one fan 20 "on" mode. A signal (e.g., LO-) may
provide for the subtraction of a temperature axis by the amount
indicated by the signal FALOND. A signal (e.g., LO+) may provide
for the addition of a temperature axis by the amount indicated by
the signal FALOFD. The temperature that corresponds to the signal
FAN_AIR_ON_DELAY_THRESH (or FADONT) is generally a higher
temperature than the temperature that corresponds to the signal
FAN_AIR_OFF_DELAY_THRESH (or FADOFT).
[0044] A control signal (e.g., FAN_AIR_TEMP_MINIMUM_TORQUE (or
FATNTQ)) may correspond to a predetermine minimum final torque
value that may be generated by the engine 10 before a predetermined
high air inlet (or intake manifold) temperature (or, alternatively,
a predetermined time when the EGR 13 is actuated) will turn on a
fan 20. A control signal (e.g., COOL_TEMP_FAN_OFF) may correspond
to a predetermined engine 10 coolant temperature below which, the
fan 20 is generally turned off. A control signal (e.g.,
COOLANT_TURNED_FAN_ON) may correspond to a mode of operation where
the at least one fan 20 was turned on in response to the engine
coolant having a temperature at or above a predetermined value. A
control signal (e.g., FAN_OFF_LINK_ENABLE or (FOLEN)) may, when
set, provide for fan 20 deactivation, and provide for a beginning
of ignition (BOI) advance signal to be disabled when both of the
intake manifold (or inlet) air and engine coolant temperatures are
equal to or less than the respective predetermined "off" levels.
When the signal FOLEN is not set, the air intake manifold (or
inlet) and engine coolant temperature conditions are generally
independent of one another.
[0045] Referring to FIG. 2b, a diagram illustrating a single-fan
implementation of the system 30 is shown. The fan actuator 36
generally turns on the fan 20 in response to the at least one
signal FAN_ON. The fan 20 may be implemented as a single-speed fan,
a multiple-speed (e.g., two-speed or dual speed, three-speed, etc.)
fan, or a variable speed fan as indicated by a variable (e.g,
FAN_TYPE or FANTYP). The signal FAN_ON is generally configured to
control the fan 20 in a single-speed mode of operation, a
multiple-speed mode of operation, or a variable speed mode of
operation to meet the design criteria of a particular application.
The fan 20 is generally implemented as a mechanically driven fan,
an electrically driven fan, or a hydraulically driven fan.
Accordingly, the actuator 36 is generally implemented as a
mechanical actuator (e.g., a clutch such as an electromagnetic
clutch), and electrical actuator (e.g., a fan relay), or a
electro-hydraulic actuator, respectively. However, the fan 20 may
be implemented with any appropriate drive mechanism to meet the
design criteria of a particular application.
[0046] The variable FAN_TYPE (or FANTYP) generally provides an
indication of the digital output fan type. In one example, the
parameter FANTYP may be implemented using the following values, "0"
may correspond to no function, "1" may correspond to single fan 20
implementation, "2" may correspond to a two (dual) fan 20
implementation, and "3" may correspond to a dual speed (two-speed)
fan 20 implementation. However, the type of the at least one fan 20
that is implemented may be indicated via any appropriate signal and
signal value to meet the design criteria of a particular
application.
[0047] When the fan 20 is implemented as a multi-speed or variable
speed fan, the fan rotational speed may be controlled by varying
(i.e., adjusting, controlling, selecting, choosing, determining,
etc.) at least one of pulse width modulation (PWM), voltage level
(or amount), and current level (or amount) of the signal FAN_ON.
However, the type of fan 20 and the speed of the fan 20 may be
controlled via any appropriate adjustment parameter to meet the
design criteria of a particular application.
[0048] Referring to FIG. 2c, a diagram illustrating a multiple-fan
(e.g., a two fan) implementation of the system 30 is shown. The
system 30 illustrated in FIG. 2c may be implemented similarly to
the system 30 illustrated in FIG. 2b. The fan 20a may be
implemented as a single speed (e.g., a low speed) fan, a
multiple-speed fan, or a variable speed fan that may be controlled
via the control signal FAN_LOW_ON. The fan 20b may be implemented
as a single speed (e.g., a high speed) fan, a multiple-speed fan,
or a variable speed fan that may be controlled via the control
signal FAN_HIGH_ON.
[0049] Referring to FIG. 3, a state diagram illustrating an
operation (i.e., process, routine, method, strategy, steps, blocks,
etc.) 100 of the present invention is shown. The method 100 may be
implemented in connection with the engine 10, the system 30, and
the controller 32 (e.g., the process 100 may be implemented in
connection with control logic in the controller 32). However, the
method 100 may be implemented in connection with any appropriate
engine, system, and controller to meet the design criteria of a
particular application. The operation 100 is generally implemented
as a single-fan engine cooling fan control routine.
[0050] The single speed fan 20 application generally implements a
single fan control output signal (e.g., the signals FAN_ON,
FAN_OFF) from the controller 32 to the actuator 36 to drive a
single speed fan 20. The fan control output signal FAN_ON is
generally not turned on (i.e., activated, presented, set, etc.)
when the engine 20 is attempting to start or within 5 seconds after
the engine 10 has started. The output signal FAN_ON is generally
turned on (i.e., activated, asserted, presented, set, etc.) (block
or state 106) when the signal FAN_AIR_DELAY_ENABLE is set, AND the
air inlet temperature is equal to or greater than the value
FAN_AIR_ON_DELAY_THRESH for at least the time FAN_AIR_TEMP_ON_TIME
(as determined via the LUT 76 in response to air inlet temperature)
(with a lower hysteresis of air inlet temperature equal to or less
than the value FAN_AIR_OFF_DELAY_THRESH for at least the time
interval FAN_AIR_TEMP_OFF_TIME AND when the variable
FAN_OFF_LINK_ENABLE is set, the engine 10 coolant temperature is
equal to or less than the value COOL_TEMP_FAN_OFF), AND the final
torque generated by the engine 10 is equal to or greater than the
value FAN_AIR_TEMP_MINIMUM_TORQUE.
[0051] The fan control with respect to the air inlet temperature
(or intake manifold 15 temperature, or alternatively time in EGR
13) may be performed via one of at least two modes of operation. In
one mode of operation, when the variable FAN_AIR_DELAY_ENABLE is
not set, the "hard" (i.e., not adjusted by a threshold offset such
as the values FAN_AIR_ON_DELAY_THRESH and FAN_AIR_OFF_DELAY_THRESH)
threshold values AIR_TEMP_FAN1_ON and AIR_TEMP_FAN_OFF are
generally referenced by the controller 32 to provide the
appropriate signals to the actuator 36 turn the fan 20 on and off,
respectively (e.g., FAN_ON and FAN_OFF).
[0052] In another mode of operation, when the variable FAN_AIR
DELAY_ENABLE is set, the variable FAN_AIR_ON_DELAY_THRESH and the
variable FAN_AIR_TEMP_ON_TIME may provide a delay (or hysteresis)
for turning on the fan 20 in response to the length of time that
the intake manifold temperature (or air inlet temperature, or
alternatively the time in EGR 13) remains above a predetermined
level. Similarly, for turning the fan off (block or state 102),
when the variable FAN_AIR_DELAY_ENABLE is set and air inlet
temperature equal to or less than the value of
FAN_AIR_OFF_DELAY_THRESH and at least the value
FAN_AIR_TEMP_OFF_TIME (as determined from the LUT 76 as a function
of air inlet temperature) may be used by the controller 32 to may
provide a delay (or hysteresis) to the length of time to determine
when to turn the fan 20 off.
[0053] The method 100 generally provides for the COUNT_ON timer 84
(block or state 104) to determine (or calculate) a value COUNT_ON
that is equal to or greater than the variable FAN_AIR_TEMP_ON_TIME.
The method 100 generally provides for the COUNT_OFF timer 84 (block
or state 108) to determine (or calculate) a value COUNT_OFF that is
equal to or greater than the variable FAN_AIR_TEMP_OFF_TIME.
[0054] When a variable (e.g., AIR_TEMP_SENSOR_FAULT_DETECTED)
indicates that there is a fault in at least one of the sensors 34
that is related to the determination of intake manifold 15 air
temperature, inlet air temperature, and EGR 13 actuation, the
controller 32 may assert the signal FAN_ON, and the fan 20 may be
operated.
[0055] Referring to FIG. 4, a state diagram illustrating a
operation (i.e., process, routine, method, steps, blocks, etc.) 200
of the present invention is shown. The method 200 may be
implemented similarly to the method 100. The method 200 is
generally implemented in connection with a two-speed fan control
application or a dual fan control application (e.g., the system 30
illustrated in FIG. 2c). The method 200 may provide at least one
mode of operation for a 2-speed fan or dual fan application in
response to air temperature (i.e., intake manifold 15 air
temperature, inlet air temperature, or alternatively, time in EGR
13) when the control signal FAN_AIR_DELAY_ENABLE is set.
[0056] The two-speed (or dual) fan application of the system 30
generally implements two control signals (e.g., the signals
FAN_LOW_ON and FAN_HIGH_ON) to drive (i.e., control) two single
speed fans 20 (e.g., a low speed fan 20a and a high speed fan 20b
or vice versa) or, alternatively, to drive a single fan 20 at a low
speed or a high (or normal) speed, respectively. The two fans 20
(or the low and high fan speeds) generally operate independently of
one another with fan 20a turning on for one set of conditions and
fan 20b turning on for a different set of conditions. The
conditions for turning on the fans 20a and 20b may be related. As
in all modes of operation, neither fan output signal FAN_LOW_ON and
FAN_HIGH_ON is turned on (block or state 202) while the engine 10
is attempting to start or within 5 seconds after having started
(i.e., the signals FAN_LOW_ON and FAN_HIGH_ON are generally not
asserted until the signal FAN_AIR_DELAY_ENABLE is TRUE).
[0057] The fan 20a may be turned on (or the low speed of the fan 20
may be turned on) (block or state 206) when the variable
FAN_AIR_DELAY_ENABLE is set, AND the air inlet temperature is equal
to or greater than the value FAN_AIR_ON_DELAY_THRESH for at least
the time FAN_AIR_TEMP_ON_TIME (as determined in the LUT 76 in
response to air inlet temperature) (with a lower hysteresis of the
air inlet temperature equal to or less than the value
FAN_AIR_OFF_DELAY_THRESH for at least the time
FAN_AIR_TEMP_OFF_TIME) AND the final torque generated by the engine
10 is equal to or greater than the value
FAN_AIR_TEMP_MINIMUM_TORQUE The fan control with respect to the air
inlet temperature can be performed via one of at least two modes of
operation. In one mode of operation, when the parameter
FAN_AIR_DELAY_ENABLE is not set, "hard" (i.e., not adjusted by a
threshold offset such as the values FAN_AIR_ON_DELAY_THRESH and
FAN_AIR_OFF_DELAY_THRESH) intake air temperature equal to or
greater than (or less than) the AIR_TEMP_FAN1_ON and
AIR_TEMP_FAN_OFF threshold values may be used to turn the fan 20a
on (block 206) and off, respectively. When the parameter
FAN_AIR_DELAY_ENABLE is set, the value FAN_AIR_ON_DELAY_THRESH and
the time duration FAN_AIR_TEMP_ON_TIME provide a delay to turning
the fan 20a on in response to the length of time that the air inlet
temperature remains equal to or higher than a predetermined value.
Similarly, for turning the fan 20a off, when the parameter
FAN_AIR_DELAY_ENABLE is set, and the air inlet temperature is equal
to or less than the predetermined value FAN_AIR OFF_DELAY_THRESH,
the FAN_AIR_TEMP_OFF_TIME (as determined form the LUT 76 in
response to air inlet temperature) may be implemented to determine
when to turn the fan 20a off (block or state 202).
[0058] A two speed fan 20 (or dual fan 20) application of the
system 30 generally implements both of the output signals
FAN_LOW_ON and FAN_HIGH_ON to drive a two speed fan 20 (or the fans
20a and 20b). When the fan control output signal FAN_LOW_ON is
asserted, the fan 20 operates in low speed mode (or the fan 20a
operates). When the fan control output signals FAN_LOW_ON and
FAN_HIGH_ON are asserted, the fan 20 generally operates in a high
speed mode (the fan 20b operates, or alternatively, or both fans
20a and 20b operate). When the two speed fan (or dual fan)
operation 200 is implemented, the air, coolant, and oil temperature
sensors may each have a low speed and high speed calibration (i.e.,
respective predetermined temperature values) to determine which fan
speed will be asserted. The air temperature based engine cooling
fan control may implement the strategy described above or the
alternative method described below in response to the state of the
variable FAN_AIR_DELAY_ENABLE.
[0059] The low speed fan 20a (or the low speed of the fan 20) may
be turned on (i.e., the signal FAN_LOW ON may be asserted) (block
or state 206) when the high speed fan 20b (or the high speed mode
of the fan 20) is not currently on or has not been turned on within
the time that corresponds to the time FAN_AIR_DELAY_ENABLE, when
the signal FAN_AIR_DELAY_ENABLE is set, AND the air inlet
temperature is equal to or greater than the FAN_AIR ON_DELAY THRESH
value minus the FAN_AIR_LOW_SPEED_ON_DELTA value for at least a
time FAN_AIR_TEMP_ON_TIME (as determined from the LUT 76 in
response to the air inlet temperature with a negative offset equal
to the value FAN_AIR_LOW_SPEED_ON_DELTA) (with a lower hysteresis
of the air inlet temperature less than the value
FAN_AIR_OFF_DELAY_THRESH for FAN_AIR_TEMP_OFF_TIME) AND the final
torque generated by the engine 10 is equal to or greater than the
value FAN_AIR_TEMP_MINIMUM_TORQUE.
[0060] The high speed fan 20b (or alternatively, the high speed
mode of the fan 20) is turned on (block or state 210) (i.e., the
output signals FAN_LOW_ON and FAN_HIGH_ON are both asserted or
turned on) when the parameter FAN_AIR_DELAY_ENABLE is set, AND the
air inlet temperature is equal to or greater than the
FAN_AIR_ON_DELAY_THRESH value for at least the time FAN_AIR_TEMP_ON
TIME (as determined via the LUT 76 in response to the air inlet
temperature) (with a lower hysteresis of the air inlet temperature
equal to or less than the value FAN_AIR_OFF_DELAY_THRESH for the
time FAN_AIR_TEMP_OFF_TIME) AND when the value FAN_OFF_LINK_ENABLE
is set, the engine coolant temperature is equal to or less than the
value COOL_TEMP_FAN_OFF AND the final torque generated by the
engine 10 is above (i.e., equal to or greater than) the value
FAN_AIR_TEMP_MINIMUM_TOR- QUE. The predetermined high speed fan 20
(e.g., fan 20b) turn-on threshold temperature is generally greater
than the predetermined low speed fan (e.g., fan 20a) turn-on
threshold temperature.
[0061] When the high speed fan 20b (or the high speed mode of the
fan 20, state 210) is turned on, the fan 20b (or the fan 20) may
switch (or transition) to a low speed mode of operation (block or
state 206) when none of the above conditions are met and when the
variable FAN_AIR_DELAY_ENABLE is set, AND the air inlet temperature
is equal to or less than the FAN_AIR_ON_DELAY_THRESH value plus the
FAN_AIR_LOW_SPEED_OFF_DELTA value for at least the interval
FAN_AIR_TEMP_OFF_TIME (as determined from the LUT 76 in response to
the air inlet temperature with a positive offset equal to the value
FAN_AIR_LOW_SPEED_OFF_DELTA) AND, the parameter FAN_OFF_LINK_ENABLE
is not set OR the BOI is not advanced based on the digital fan
controls (with a lower hysteresis of air inlet temperature equal to
or less than the value FAN_AIR OFF_DELAY_THRESH for at least the
interval FAN_AIR_TEMP_OFF_TIME (for fan off transition)).
[0062] The method 200 generally provides for the COUNT_LOW_ON timer
84 (block or state 204) to determine (or calculate) a value
COUNT_LOW_ON that is equal to or greater than the variable
FAN_AIR_TEMP_ON_TIME minus the temperature axis determined by the
value FAN_AIR_LOW_SPEED_ON_DELTA. The method 200 generally provides
for the COUNT_LOW_OFF timer 84 (block or state 208) to determine
(or calculate) when the value COUNT_LOW_OFF is equal to or greater
than the variable FAN_AIR_TEMP_OFF_TIME. The method 200 generally
provides for the COUNT_HIGH_ON timer 84 (block or state 212) to
determine (or calculate) when the value COUNT_HIGH_ON is equal to
or greater than the variable FAN_AIR_TEMP_ON_TIME. The method 200
generally enables the COUNT_HIGH_OFF timer 84 (block or state 214)
to determine (or calculate) when the value COUNT_HIGH_OFF is equal
to or greater than the variable FAN_AIR_TEMP_OFF_TIME.
[0063] When the variable AIR_TEMP_SENSOR_FAULT_DETECTED indicates
that there is a fault in at least one of the sensors 34 that is
related to the determination of intake manifold 15 air temperature,
inlet air temperature, and EGR 13 actuation, the controller 32 may
assert the signal FAN_HIGH_ON, and the high speed fan 20b may be
turned on or the fan 20 may be operated in a high speed mode.
[0064] As is readily apparent from the foregoing description, then,
the present invention generally provides an improved apparatus
(e.g., the system 30) and an improved method (e.g., the method 100
and the method 200) for controlling an engine cooling fan. The
improved system and method of the present invention may provide a
greater number of input and output control parameters than
conventional approaches. Furthermore, the present invention may
provide more flexible engine control (i.e., a greater number of
modes of control) when compared to conventional approaches.
[0065] While the control signals of the present invention have been
described as set when the signal is "on", enabled, asserted,
presented, transmitted, at a logic TRUE, HIGH or "1" state or
level, etc., the control signals may be set when "off", disabled,
de-asserted, not presented, not transmitted, at a logic FALSE, LOW
or "0" state or level, etc., or alternatively, any of the control
signal states may be reversed or inverted to meet the design
criteria of a particular application.
[0066] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *