U.S. patent application number 16/675815 was filed with the patent office on 2021-05-06 for system and method for reducing engine temperature.
The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to Julia Helen Buckland Seeds, John Erik Mikael Hellstrom, Douglas Raymond Martin, Adam J. Richards, John Eric Rollinger, Joshua Schumaker, Joseph Lyle Thomas.
Application Number | 20210131360 16/675815 |
Document ID | / |
Family ID | 1000005535265 |
Filed Date | 2021-05-06 |
![](/patent/app/20210131360/US20210131360A1-20210506\US20210131360A1-2021050)
United States Patent
Application |
20210131360 |
Kind Code |
A1 |
Martin; Douglas Raymond ; et
al. |
May 6, 2021 |
SYSTEM AND METHOD FOR REDUCING ENGINE TEMPERATURE
Abstract
Systems and methods for cooling an internal combustion engine
via flowing air through the internal combustion engine during
select conditions are presented. In one example, lift of intake
and/or exhaust poppet valves may be adjusted as a function of
engine temperature. In addition, opening and closing timings of
intake and exhaust poppet valves may be adjusted as a function of
engine temperature.
Inventors: |
Martin; Douglas Raymond;
(Canton, MI) ; Rollinger; John Eric; (Troy,
MI) ; Buckland Seeds; Julia Helen; (Commerce
Township, MI) ; Thomas; Joseph Lyle; (Farmington
Hills, MI) ; Schumaker; Joshua; (Dearborn, MI)
; Hellstrom; John Erik Mikael; (Ann Arbor, MI) ;
Richards; Adam J.; (Canton, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Family ID: |
1000005535265 |
Appl. No.: |
16/675815 |
Filed: |
November 6, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02D 9/02 20130101; F02D
41/3005 20130101; F02D 17/02 20130101; F02D 13/023 20130101; F02D
2200/021 20130101 |
International
Class: |
F02D 17/02 20060101
F02D017/02; F02D 13/02 20060101 F02D013/02; F02D 9/02 20060101
F02D009/02; F02D 41/30 20060101 F02D041/30 |
Claims
1. An engine control method, comprising: deactivating an engine
cylinder of an engine in response to an engine temperature
exceeding a threshold temperature; and adjusting an amount of lift
of an intake valve of the engine cylinder that is deactivated and
flowing air through the engine cylinder that is deactivated in
response to the engine temperature exceeding the threshold
temperature.
2. The method of claim 1, further comprising advancing an opening
time of the intake valve in response to the engine temperature
exceeding the threshold temperature.
3. The method of claim 1, further comprising deactivating one or
more additional engine cylinders in response to the engine
temperature exceeding the threshold temperature, and where
adjusting the amount of lift of the intake valve includes
increasing the amount of lift of the intake valve as the engine
temperature increases while the engine cylinder is deactivated and
decreasing the amount of lift of the intake valve as the engine
temperature decreases while the engine cylinder is deactivated.
4. The method of claim 1, where the engine cylinder is deactivated
via ceasing fuel flow to the engine cylinder, and further
comprising decreasing an amount of lift of intake valves of
activated cylinders of the engine and increasing an opening amount
of an intake throttle of the engine in response to the engine
temperature exceeding the threshold temperature.
5. The method of claim 1, further comprising reducing an engine
torque limit in response to the engine temperature exceeding the
threshold temperature.
6. The method of claim 1, further comprising delivering a driver
demand torque via activated cylinders after deactivating the engine
cylinder.
7. The method of claim 1, further comprising deactivating a second
cylinder with intake valves of the second cylinder held closed
during an engine cycle in response to the engine temperature
exceeding the threshold temperature.
8. An engine system, comprising: an engine including a cylinder,
the cylinder including a variable lift and timing poppet valve; and
a controller including executable instructions stored in
non-transitory memory that cause the controller to deactivate the
cylinder and adjust an amount of lift of the variable lift and
timing poppet valve to a non-zero lift amount that varies with a
temperature of the engine in response to the temperature of the
engine.
9. The system of claim 8, where the cylinder is deactivated via
ceasing fuel to the cylinder.
10. The system of claim 8, further comprising additional
instructions to adjust an amount of lift of a variable lift and
timing poppet valve of a second cylinder in response to the
temperature of the engine such that the amount of lift increases
with increasing engine temperature.
11. The system of claim 10, where adjusting the amount of lift
includes increasing the amount of lift of the variable lift and
timing poppet valve.
12. The system of claim 10, where adjusting the amount of lift
includes decreasing the amount of lift of the variable lift and
timing poppet valve.
13. The system of claim 8, further comprising additional
instructions to increase an opening amount of a throttle and
decreasing an intake valve lift amount of an active cylinder in
response to the temperature of the engine.
14. The system of claim 8, further comprising additional
instructions to decrease an engine torque limit in response to the
temperature of the engine.
15. An engine control method, comprising: deactivating one or more
cylinders of a plurality of cylinders of an engine in response to
an engine temperature exceeding a threshold temperature; adjusting
which of the plurality of cylinders is deactivated while the engine
temperature exceeds the threshold temperature; and adjusting air
flow through the deactivated one or more cylinders as a function of
the engine temperature via adjusting an amount of valve lift of
intake valves of the deactivated one or more cylinders to a
non-zero value.
16. The method of claim 15, where adjusting air flow through the
deactivated one or more cylinders includes increasing the amount of
valve lift of intake valves of the deactivated one or more
cylinders as engine temperature increases.
17. The method of claim 15, where adjusting air flow through the
deactivated one or more cylinders includes advancing an opening
timing of intake valves of the deactivated one or more
cylinders.
18. The method of claim 15, where adjusting air flow through the
deactivated one or more cylinders includes adjusting a position of
a throttle.
19. The method of claim 15, further comprising adjusting air flow
through activated cylinders included in the plurality of cylinders
based on a driver demand torque.
20. The method of claim 15, where adjusting which of the plurality
of cylinders is deactivated includes changing which of the
plurality of cylinders is deactivated between two engine cycles.
Description
FIELD
[0001] The present description relates to a system and methods for
controlling temperature of an internal combustion engine. The
system and methods may be applied when liquid engine coolant is
insufficient to maintain engine temperature less than a threshold
temperature.
BACKGROUND AND SUMMARY
[0002] An engine may be cooled via a liquid coolant. The liquid
coolant is typically circulated within a coolant system via a pump.
The liquid coolant may pass through the engine where it is heated,
after being heated the coolant may flow to a radiator where it may
be cooled via ambient air. The liquid coolant may be recirculated
back to the engine where it may again cool the engine. Under most
conditions, the liquid coolant is more than sufficient to cool the
engine. However, there may be times when engine cooling via the
engine coolant is insufficient to maintain engine temperature to
less than a threshold temperature. For example, if the vehicle is
driven over an object that pierces the engine coolant system, the
liquid coolant may not be retained in the coolant system. In
addition, operation of a thermostat within the engine coolant
system may degrade over time such that the thermostat restricts
coolant flow from the engine. Consequently, engine temperature may
rise above a threshold temperature during these conditions.
Therefore, it may be desirable to provide a way of cooling an
engine during conditions when engine coolant may be insufficient to
cool the engine.
[0003] The inventors herein have recognized the above-mentioned
issues and have developed an engine control method, comprising:
deactivating an engine cylinder in response to an engine
temperature exceeding a threshold temperature; and adjusting an
amount of lift of an intake valve of the engine cylinder in
response to the engine temperature exceeding the threshold
temperature.
[0004] By deactivating one or more cylinders and adjusting an
amount of lift of an intake valve in response to an engine
temperature exceeding a threshold temperature, it may be possible
to provide the technical result of cooling an engine without
flowing excessive amounts of air through the engine. In particular,
an amount of air that flows through the engine may be adjusted as a
function of engine temperature so that air that flows through the
engine and reaches a catalyst may be small enough to allow the
catalyst to operate at a higher efficiency level. In addition, the
deactivated cylinders that air flows through may be changed from
engine cycle to engine cycle so that all cylinders are cooled
nearly equally, thereby reducing the possibility of localized
higher engine temperatures.
[0005] The present description may provide several advantages. In
particular, the approach may reduce the possibility of an engine
temperature exceeding an upper threshold limit. Further, the
approach may provide for improved catalyst efficiency when the
engine is being cooled via air flowing through the engine. The
approach may also adjust timing of deactivated cylinders to control
air flow through the engine so that air flow through the engine may
be adjusted to suit engine cooling requirements and to improve
catalyst efficiency.
[0006] The above advantages and other advantages, and features of
the present description will be readily apparent from the following
Detailed Description when taken alone or in connection with the
accompanying drawings.
[0007] It should be understood that the summary above is provided
to introduce in simplified form a selection of concepts that are
further described in the detailed description. It is not meant to
identify key or essential features of the claimed subject matter,
the scope of which is defined uniquely by the claims that follow
the detailed description. Furthermore, the claimed subject matter
is not limited to implementations that solve any disadvantages
noted above or in any part of this disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The advantages described herein will be more fully
understood by reading an example of an embodiment, referred to
herein as the Detailed Description, when taken alone or with
reference to the drawings, where:
[0009] FIG. 1 is a schematic diagram of an engine;
[0010] FIG. 2A is a schematic diagram of an eight cylinder engine
with two cylinder banks;
[0011] FIG. 2B is a schematic diagram of a four cylinder engine
with a single cylinder bank;
[0012] FIG. 3 is plot of an example engine operating sequence
according to the method of FIG. 4; and
[0013] FIG. 4 shows a flow chart of an example method for operating
an engine.
DETAILED DESCRIPTION
[0014] The present description is related to cooling an engine via
flowing air through the engine without the air participating in
combustion. The air that flows through the engine may carry heat
from the engine out the engine's exhaust system, thereby cooling
the engine. The approach also includes adjusting the amount of air
that flows through the engine via adjusting engine valve lift
and/or timing. The amount of air flowing through the engine may be
based on the temperature of the engine so that if engine
temperature is only slightly higher than is expected, the air flow
amount through the engine may be small. The smaller air flow amount
may help to keep the catalyst operating at a higher level of
efficiency. FIG. 1 shows a schematic view of an example engine.
FIGS. 2A and 2B show two example configurations of the engine that
is shown in FIG. 1. FIG. 3 shows an engine operating sequence
according to the method of FIG. 4. A method for operating an engine
with variable valve lift to provide engine cooling is shown in FIG.
4.
[0015] Referring to FIG. 1, internal combustion engine 10,
comprising a plurality of cylinders, one cylinder of which is shown
in FIG. 1, is controlled by electronic engine controller 12. Engine
10 includes combustion chamber 30 and cylinder walls 32 with piston
36 positioned therein and connected to crankshaft 40.
[0016] Combustion chamber 30 is shown communicating with intake
manifold 44 and exhaust manifold 48 via respective intake valve 52
and exhaust valve 54. Each intake and exhaust valve may be operated
by a variable intake valve operator 51 and a variable exhaust valve
operator 53, which may be actuated mechanically, electrically,
hydraulically, or by a combination of the same. For example, the
valve actuators may be of the type described in U.S. Pat. Nos.
6,321,704; 6,273,039; 7,869,929 and 7,458,345, which are hereby
fully incorporated for all intents and purposes. Intake valve
operator 51 and an exhaust valve operator 53 may open intake 52 and
exhaust 54 valves synchronously or asynchronously with crankshaft
40. The position of intake valve 52 may be determined by intake
valve position sensor 55. The position of exhaust valve 54 may be
determined by exhaust valve position sensor 57.
[0017] Fuel injector 66 is shown positioned to inject fuel directly
into cylinder 30, which is known to those skilled in the art as
direct injection. Alternatively, fuel may be injected to an intake
port, which is known to those skilled in the art as port injection.
Fuel injector 66 delivers liquid fuel in proportion to the pulse
width of signal from controller 12. Fuel is delivered to fuel
injector 66 by a fuel system 175. In one example, a high pressure,
dual stage, fuel system may be used to generate higher fuel
pressures. In addition, intake manifold 44 is shown communicating
with optional electronic throttle 62 (e.g., a butterfly valve)
which adjusts a position of throttle plate 64 to control air flow
from air filter 43 and air intake 42 to intake manifold 44.
Throttle 62 regulates air flow from air filter 43 in engine air
intake 42 to intake manifold 44. In some examples, throttle 62 and
throttle plate 64 may be positioned between intake valve 52 and
intake manifold 44 such that throttle 62 is a port throttle.
[0018] Distributorless ignition system 88 provides an ignition
spark to combustion chamber 30 via spark plug 92 in response to
controller 12. Universal Exhaust Gas Oxygen (UEGO) sensor 126 is
shown coupled to exhaust manifold 48 upstream of catalytic
converter 70. Alternatively, a two-state exhaust gas oxygen sensor
may be substituted for UEGO sensor 126.
[0019] Converter 70 can include multiple catalyst bricks, in one
example. In another example, multiple emission control devices,
each with multiple bricks, can be used. Converter 70 can be a
three-way type catalyst in one example.
[0020] Controller 12 is shown in FIG. 1 as a conventional
microcomputer including: microprocessor unit 102, input/output
ports 104, read-only memory 106 (e.g., non-transitory memory),
random access memory 108, keep alive memory 110, and a conventional
data bus. Controller 12 is shown receiving various signals from
sensors coupled to engine 10, in addition to those signals
previously discussed, including: engine coolant temperature (ECT)
from temperature sensor 112 coupled to cooling sleeve 114; a
position sensor 134 coupled to an accelerator pedal 130 for sensing
force applied by human driver 132; a measurement of engine manifold
pressure (MAP) from pressure sensor 122 coupled to intake manifold
44; an engine position sensor from a Hall effect sensor 118 sensing
crankshaft 40 position; a measurement of air mass entering the
engine from sensor 120; brake pedal position from brake pedal
position sensor 154 when human driver 132 applies brake pedal 150;
and a measurement of throttle position from sensor 58. Barometric
pressure may also be sensed (sensor not shown) for processing by
controller 12. In a preferred aspect of the present description,
engine position sensor 118 produces a predetermined number of
equally spaced pulses every revolution of the crankshaft from which
engine speed (RPM) can be determined.
[0021] In some examples, the engine may be coupled to an electric
motor/battery system in a hybrid vehicle. Further, in some
examples, other engine configurations may be employed, for example
a diesel engine.
[0022] During operation, each cylinder within engine 10 typically
undergoes a four stroke cycle: the cycle includes the intake
stroke, compression stroke, expansion stroke, and exhaust stroke.
During the intake stroke, generally, the exhaust valve 54 closes
and intake valve 52 opens. Air is introduced into combustion
chamber 30 via intake manifold 44, and piston 36 moves to the
bottom of the cylinder so as to increase the volume within
combustion chamber 30. The position at which piston 36 is near the
bottom of the cylinder and at the end of its stroke (e.g. when
combustion chamber 30 is at its largest volume) is typically
referred to by those of skill in the art as bottom dead center
(BDC). During the compression stroke, intake valve 52 and exhaust
valve 54 are closed. Piston 36 moves toward the cylinder head so as
to compress the air within combustion chamber 30. The point at
which piston 36 is at the end of its stroke and closest to the
cylinder head (e.g. when combustion chamber 30 is at its smallest
volume) is typically referred to by those of skill in the art as
top dead center (TDC). In a process hereinafter referred to as
injection, fuel is introduced into the combustion chamber. In a
process hereinafter referred to as ignition, the injected fuel is
ignited by known ignition means such as spark plug 92, resulting in
combustion. During the expansion stroke, the expanding gases push
piston 36 back to BDC. Crankshaft 40 converts piston movement into
a rotational torque of the rotary shaft. Finally, during the
exhaust stroke, the exhaust valve 54 opens to release the combusted
air-fuel mixture to exhaust manifold 48 and the piston returns to
TDC. Note that the above is shown merely as an example, and that
intake and exhaust valve opening and/or closing timings may vary,
such as to provide positive or negative valve overlap, late intake
valve closing, or various other examples.
[0023] Referring now to FIG. 2A, an example multi-cylinder engine
that includes two cylinder banks is shown. The engine includes
cylinders and associated components as shown in FIG. 1. Engine 10
includes eight cylinders 210. Each of the eight cylinders is
numbered and the numbers of the cylinders are included within the
cylinders. Fuel injectors 66 selectively supply fuel to each of the
cylinders that are activated (e.g., combusting fuel during a cycle
of the engine). Cylinders 1-8 may be selectively deactivated to
improve engine fuel economy when less than the engine's full torque
capacity is requested. For example, cylinders 2, 3, 5, and 8 (e.g.,
a fixed pattern of deactivated cylinders) may be deactivated during
an engine cycle (e.g., two revolutions for a four stroke engine)
and may be deactivated for a plurality of engine cycles while
engine speed and load are constant or vary slightly. During a
different engine cycle, a second fixed pattern of cylinders 1, 4,
6, and 7 may be deactivated. Further, other patterns of cylinders
may be selectively deactivated based on vehicle operating
conditions. Additionally, engine cylinders may be deactivated such
that a fixed pattern of cylinders is not deactivated over a
plurality of engine cycles. Rather, cylinders that are deactivated
may change from one engine cycle to the next engine cycle. For
example, during a first engine cycle, cylinders 1, 4, 6, and 7 may
be deactivated while cylinders 2, 3, 5, and 8 are activated, during
a second engine cycle that immediately follows the first engine
cycle, cylinders 2 and 5 may be activated while cylinders 1, 3, 4,
and 6-8 are deactivated. Each cylinder includes variable intake
valve operators 51 and variable exhaust valve operators 53. An
engine cylinder may be deactivated by its variable intake valve
operators 51 and variable exhaust valve operators holding intake
and exhaust valves of the cylinder closed during an entire cycle of
the cylinder. An engine cylinder may be activated by its variable
intake valve operators 51 and variable exhaust valve operators 53
opening and closing intake and exhaust valves of the cylinder
during a cycle of the cylinder. Engine 10 includes a first cylinder
bank 204, which includes four cylinders 1, 2, 3, and 4. Engine 10
also includes a second cylinder bank 202, which includes four
cylinders 5, 6, 7, and 8. Cylinders of each bank may be active or
deactivated during a cycle of the engine.
[0024] Referring now to FIG. 2B, an example multi-cylinder engine
that includes one cylinder banks is shown. The engine includes
cylinders and associated components as shown in FIG. 1. Engine 10
includes four cylinders 210. Each of the four cylinders is numbered
and the numbers of the cylinders are included within the cylinders.
Fuel injectors 66 selectively supply fuel to each of the cylinders
that are activated (e.g., combusting fuel during a cycle of the
engine with intake and exhaust valves opening and closing during a
cycle of the cylinder that is active). Cylinders 1-4 may be
selectively deactivated (e.g., not combusting fuel during a cycle
of the engine with intake and exhaust valves held closed over an
entire cycle of the cylinder being deactivated) to improve engine
fuel economy when less than the engine's full torque capacity is
requested. For example, cylinders 2 and 3 (e.g., a fixed pattern of
deactivated cylinders) may be deactivated during a plurality of
engine cycles (e.g., two revolutions for a four stroke engine).
During a different engine cycle, a second fixed pattern cylinders 1
and 4 may be deactivated over a plurality of engine cycles.
Further, other patterns of cylinders may be selectively deactivated
based on vehicle operating conditions. Additionally, engine
cylinders may be deactivated such that a fixed pattern of cylinders
is not deactivated over a plurality of engine cycles. Rather,
cylinders that are deactivated may change from one engine cycle to
the next engine cycle. For example, during a first engine cycle,
cylinders 1 and 4 may be deactivated while cylinders 2 and 3 are
activated, during a second engine cycle that immediately follows
the first engine cycle, cylinders 1 and 4 may be activated while
cylinders 2 and 3 are deactivated. In this way, the deactivated
engine cylinders may rotate or change from one engine cycle to the
next engine cycle.
[0025] Engine 10 includes a single cylinder bank 250, which
includes four cylinders 1-4. Cylinders of the single bank may be
active or deactivated during a cycle of the engine. Each cylinder
includes variable intake valve operators 51 and variable exhaust
valve operators 53. An engine cylinder may be deactivated by its
variable intake valve operators 51 and variable exhaust valve
operators holding intake and exhaust valves of the cylinder closed
during a cycle of the cylinder. An engine cylinder may be activated
by its variable intake valve operators 51 and variable exhaust
valve operators 53 opening and closing intake and exhaust valves of
the cylinder during a cycle of the cylinder.
[0026] The system of FIGS. 1-2B provides for an engine system,
comprising: an engine including a cylinder, the cylinder including
a variable lift and timing poppet valve; and a controller including
executable instructions stored in non-transitory memory that cause
the controller to deactivate the cylinder and adjust an amount of
lift of the variable lift and timing poppet valve in response to a
temperature of the engine. The system includes where the cylinder
is deactivated via ceasing fuel to the cylinder. The system further
comprises additional instructions to adjust an amount of lift of a
variable lift and timing poppet value of a second cylinder in
response to the temperature of the engine. The system includes
where adjusting the amount of lift includes increasing the amount
of lift. The system includes where adjusting the amount of lift
includes decreasing the amount of lift. The system further
comprises additional instructions to increase an opening amount of
a throttle in response to the temperature of the engine. The system
further comprises additional instructions to decrease an engine
torque limit in response to the temperature of the engine.
[0027] Referring now to FIG. 3, plots of a prophetic engine
operating sequence are shown. The plots are aligned in time and
occur at the same time. The vertical lines at times t0-t2 represent
times of interest during the operating sequence. The sequence may
be provided by the system of FIGS. 1 and 2A according to the method
of FIG. 4. In this example, driver demand torque (not shown) is
held constant during the sequence for simplification purposes.
[0028] The first plot from the top of FIG. 3 is a plot of engine
temperature verses time. The vertical axis represents engine
temperature and engine temperature increases in the direction of
the vertical axis arrow. The horizontal axis represents time and
time increases in the direction of the horizontal axis arrow.
Horizontal line 350 represents a threshold temperature above which
one or more cylinders may be deactivated to reduce engine
temperature. Trace 302 represents the engine temperature.
[0029] The second plot from the top of FIG. 3 is a plot of engine
cylinder deactivation state versus time. The vertical axis
represents the engine cylinder deactivation state and the cylinder
deactivation state is asserted when trace 304 is at a level that is
near the vertical axis arrow. The cylinder deactivation state is
not asserted when trace 304 is at a level that is near the
horizontal axis. One or more engine cylinders are deactivated when
the cylinder deactivation state is asserted. The horizontal axis
represents time and time increases in the direction of the
horizontal axis arrow. Trace 304 represents the cylinder
deactivation state.
[0030] The third plot from the top of FIG. 3 is a plot of valve
lift of active engine cylinders versus time. The vertical axis
represents the valve lift of active engine cylinders and the valve
lift of active engine cylinders increases in the direction of the
vertical axis arrow. The valve lift of active cylinders is zero
when trace 306 is at a level of the horizontal axis. The horizontal
axis represents time and time increases in the direction of the
horizontal axis arrow. Trace 306 represents the active cylinder
valve lift amount.
[0031] The fourth plot from the top of FIG. 3 is a plot of valve
lift of deactivated engine cylinders versus time. The vertical axis
represents the valve lift of deactivated engine cylinders and the
valve lift of deactivated engine cylinders increases in the
direction of the vertical axis arrow. The valve lift of deactivated
cylinders is zero when trace 308 is at a level of the horizontal
axis. The horizontal axis represents time and time increases in the
direction of the horizontal axis arrow. Trace 308 represents the
deactivated cylinder valve lift amount.
[0032] The fifth plot from the top of FIG. 3 is a plot of engine
throttle position versus time. The vertical axis represents the
engine throttle position and the throttle position increases (e.g.,
opens further) in the direction of the vertical axis arrow. The
engine throttle valve position is fully closed when trace 310 is at
a level of the horizontal axis. The horizontal axis represents time
and time increases in the direction of the horizontal axis arrow.
Trace 310 represents the engine throttle position.
[0033] The sixth plot from the top of FIG. 3 is a plot of an engine
torque limit versus time. The vertical axis represents the engine
torque limit (e.g., a torque that the engine is not permitted to
exceed) and the engine torque limit increases in the direction of
the vertical axis arrow. The horizontal axis represents time and
time increases in the direction of the horizontal axis arrow. Trace
312 represents the engine torque limit.
[0034] At time t0, the engine temperature is below threshold 350
and it is increasing. The engine's cylinders are not deactivated
and the valve lift of activated cylinders is at a middle level. The
valve lift of deactivated cylinders is not indicated because
cylinders are not deactivated. The engine throttle is open a middle
level amount and the engine torque limit is a higher value.
[0035] At time t1, the engine temperature exceeds threshold 350 so
one or more engine cylinders are deactivated. The cylinder
deactivation state changes to an active level and the active
cylinder valve lift is reduced. In addition, the throttle opening
amount is increased and the valve lift of deactivated cylinders is
now indicated at a middle level. The engine torque limit is
reduced. The valves of the deactivated cylinders continue to open
and close such that air is pumped through the deactivated cylinders
causing the air to cool the engine. The cylinders are deactivated
via ceasing fuel injection and spark to the deactivated cylinders.
The lift of the active cylinders is decreased because the throttle
opening amount is increased, which allows additional air to flow
into the engine's intake manifold.
[0036] Between time t1 and time t2, the engine temperature
continues to increase. The valve lift of deactivated cylinders
increases as engine temperature increases so that additional cool
air may flow through the engine, thereby cooling the engine. The
engine torque limit is also decreased as the engine temperature
increases so that the engine temperature rise may be limited. The
valve lift of activated cylinders remains constant since the driver
demand torque is constant in this example. The throttle opening
amount also remains constant and engine cylinders are still
deactivated.
[0037] At the time that is nearly in the middle of time t1 and time
t2, the engine temperature begins to decrease. The engine
temperature decrease may be attributed to air flow through the
engine cooling the engine and/or coolant being allowed to flow
through the engine (e.g., release of a temporarily stuck closed
engine coolant thermostat). The valve lift of deactivated cylinders
is reduced in response to the decreasing engine temperature and the
engine torque limit is raised in response to the decreasing engine
temperature. One or more engine cylinders continue to be
deactivated.
[0038] At time t2, the engine temperature falls below threshold 350
so cylinders are no longer deactivated to cool the engine with air.
The throttle is partially closed and the engine torque limit is
increased. The valve lift of active engine cylinders is increased
since the throttle opening amount is decreased and since the number
of active cylinders is increased.
[0039] In this way, valve lift of deactivated cylinders may be
adjusted as a function of engine temperature so that an engine may
be cooled via flowing air through the engine while reducing the
possibility of excessive air flow through the engine. Further,
catalyst efficiency may be maintained via adjusting valve lift
and/or timing as a function of engine temperature.
[0040] Referring now to FIG. 4, a flow chart of a method for
operating an engine is shown. The method of FIG. 4 may be
incorporated into and may cooperate with the system of FIGS. 1-2B.
Further, at least portions of the method of FIG. 4 may be
incorporated as executable instructions stored in non-transitory
memory of a controller that cause the controller to perform
specific actions. The controller may transform operating states of
devices and actuators in the physical world to perform the
method.
[0041] At 402, method 400 determines vehicle operating conditions.
Vehicle operating conditions may include, but are not limited to
engine temperature, driver demand torque, engine air flow amount,
engine speed, and ambient air temperature. Method 400 may determine
the various operating conditions via the sensors and actuators
described herein. Method 400 proceeds to 404 after determining the
vehicle operating conditions.
[0042] At 404, method 400 judges if engine temperature is greater
than a threshold temperature. The engine temperature may be a
temperature of a cylinder head, engine coolant temperature, engine
oil temperature, or a different engine temperature. The threshold
engine temperature may be a function of driver demand torque and
engine speed. If method 400 judges that an engine temperature is
greater than or equal to the threshold temperature, then the answer
is yes and method 400 proceeds to 406. Otherwise, the answer is no
and method 400 proceeds to 420.
[0043] At 420, method 400 operates engine popper valves (e.g.,
engine intake and exhaust poppet valves) at baseline lift amounts
with baseline valve opening and closing timings. The baseline valve
lift amounts and baseline valve opening and closing timings may be
a function of driver demand torque and engine speed. Further, in
vehicle systems that include an engine intake throttle, the
throttle opening amount may be adjusted to a baseline opening
amount that is a function of requested engine air flow according to
driver demand torque and engine speed. The baseline valve lift
amounts, baseline valve opening timings and closing timings, and
throttle opening amount may be stored in controller memory and they
may be retrieved via referencing one or more functions and/or
tables via driver demand torque and engine speed while operating
the engine. The baseline valve lift amounts, baseline valve opening
timings and closing timings, and throttle opening amount may be
empirically determined via operating the engine on a dynamometer.
Method 400 proceeds to exit after adjusting the engine throttle,
poppet valve lift, and poppet valve opening and closing timings
(e.g., poppet valve opening and closings relative to crankshaft
position) according to baseline opening amounts, lift amounts, and
timing amounts.
[0044] At 406, method 400 adjusts an engine torque upper threshold
limit (e.g., a threshold that engine torque is not permitted to
exceed) as a function of engine temperature. In one example, the
engine torque upper threshold limit is decreased as engine
temperature increases. By reducing the engine torque upper
threshold limit, engine torque may be constrained so that engine
temperature may not increase to higher levels that may not be
managed via flowing air through the engine. Method 400 proceeds to
408.
[0045] At 408, method 400 deactivates one or more engine cylinders
in response to engine temperature being greater than a threshold
temperature. The actual total number of deactivated cylinders, or
alternatively, the actual total number of activated cylinders may
be a function of the engine temperature. Further, method 400 may
rotate the cylinders that are deactivated each engine cycle. For
example, during a first cycle of an eight cylinder engine,
cylinders 2, 3, 5, and 8 may be deactivated with intake and exhaust
valves that continue to open and close while the cylinders are
deactivated. Cylinders 1, 4, 6, and 7 remain active during the
first engine cycle. During a second engine cycle immediately
following the first engine cycle, cylinders 1, 4, 6, and 7 are
deactivated with intake and exhaust valves that continue to open
and close while cylinders 2, 3, 5, and 8 are active. In addition,
the actual total number of cylinders that are deactivated may be
based on the driver demand torque.
[0046] In one example, if the engine is an eight cylinder engine,
method 400 may deactivate two engine cylinders via ceasing fuel
flow to the two deactivated cylinders. The valves of these
cylinders continue to operate to allow fresh air that has not
participated in combustion to pass through the two deactivated
cylinders, thereby air cooling the engine. If the driver demand
torque is low, two additional cylinders may be deactivated via
ceasing fuel flow to these two cylinders and by holding intake and
exhaust valves of these cylinders in closed positions over an
entire engine cycle. Thus, intake and exhaust poppet valves of two
deactivated cylinders may continue to allow air flow through two
deactivated cylinders and intake and exhaust poppet valves of two
deactivated cylinders may be held closed over one or more engine
cycles to conserve fuel. Four cylinders remain active in this
example to meet and provide the driver demand torque. If the engine
temperature continues to increase, then the intake and exhaust
poppet valves of four deactivated cylinders may operate to allow
additional an increased amount of air to flow though the engine
without having participated in combustion within the engine. The
engine may still continue to operate with four active cylinders if
the driver demand torque remains low. However, if the engine
temperature does not increase and driver demand torque increases to
a level requiring more than four active cylinders, then the actual
total number of activated cylinders (e.g., cylinders that are
combusting air and fuel) may be increased to meet the driver demand
torque while two cylinders remain deactivated with operating intake
and exhaust valves.
[0047] In one example, method 400 references a first table or
function that outputs an actual total number of engine cylinders to
deactivate with operating intake and exhaust valves that allow air
to flow through the deactivated cylinders according to engine
temperature. Method 400 also accesses a second table or function
that requests an actual total number of active cylinders, or
alternatively, an actual total number of deactivated cylinders via
driver demand torque and engine speed. The actual total number of
deactivated engine cylinders that is based on engine temperature
may have priority so that method 400 deactivates the actual total
number of cylinders based on engine temperature. However, if the
actual number of deactivated cylinders based on driver demand
torque is greater than the actual total number of cylinder to
deactivate based on engine temperature, then method 400 deactivates
additional cylinders, but poppet valves of these additional
cylinders may be held in a closed state during an engine cycle.
Thus, method 400 may deactivate several cylinders and some of the
deactivated cylinders may have intake and exhaust valves that open
and close during an engine cycle while other deactivated cylinders
have intake and exhaust valves that remain closed during the engine
cycle. This may allow the engine to conserve fuel and maintain
catalyst efficiency. Method 400 proceeds to 410 after engine
cylinders have been deactivated according to engine
temperature.
[0048] At 410, method 400 increases an engine throttle opening
amount, if an engine throttle is present. By increasing the
throttle opening amount, it may be possible to increase the amount
of air flowing through the engine to increase engine cooling.
Method 400 also adjusts an amount of valve lift for operating
poppet valves of cylinders that are deactivated as a function of
engine temperature. For example, method 400 may increase a valve
lift amount of intake poppet valves for operating intake poppet
valves of deactivated cylinders as engine temperature increases
beyond a threshold temperature. For example, a lift amount of an
intake poppet valve for an operating intake poppet valve of a
deactivated cylinder may be increased from 6 millimeters to 7
millimeters when a threshold engine temperature is exceeded by
2.degree. C. The intake poppet valve lift amount for the intake
poppet valve may be increased to 8 millimeters when the threshold
engine temperature is exceeded by 3.degree. C. Method 400 may
increase lift exhaust poppet valves that are operating in
deactivated cylinders similarly as a function of engine
temperature. The increased poppet valve lift may increase air flow
through the engine, thereby increasing engine cooling.
[0049] Additionally, or alternatively, method 400 may adjust intake
and/or exhaust poppet valve opening timing (relative to crankshaft
position) and closing timing for deactivated cylinders as a
function of engine temperature exceeding the threshold engine
temperature. For example, intake and exhaust poppet valve timings
may be adjusted so that air may have more time to flow into a
deactivated cylinder during an intake stroke of the deactivated
cylinder as engine temperature increases so that engine cooling may
be increased via the increased air flow through the engine.
Likewise, exhaust valve timings may be adjusted to allow a longer
amount of time for air to pass through the cylinder and into the
exhaust system so that engine air flow may be increased, thereby
increasing engine cooling. In one example, intake valve timing may
be advanced to increase air flow through the engine when engine
temperature increases. In another example, intake valve timing may
be retarded to increase air flow though the engine when engine
temperature rises.
[0050] Method 400 may also increase intake poppet valve lift
amounts for active engine cylinders (e.g., cylinders that are
combusting air and fuel) as a function of driver demand torque and
engine speed. In particular, method 400 may increase intake poppet
valve lift as driver demand torque increases. Additionally, or
alternatively, method 400 may adjust intake and/or exhaust poppet
valve opening timings (relative to crankshaft position) and closing
timings for active engine cylinders as a function of driver demand
torque. For example, intake and exhaust poppet valve timing may be
adjusted so that air may have more time to flow into an activated
cylinder during an intake stroke of the activated cylinder as
driver demand torque increases so that additional torque may be
generated by the engine. Likewise, exhaust valve timing may be
adjusted to allow a longer amount of time for exhaust gases to pass
through the cylinder and into the exhaust system so that exhaust
may be expelled from the cylinder, thereby increasing engine air
flow. Method 400 proceeds to exit after adjusting poppet valve
lift, poppet valve timing, and throttle opening amount.
[0051] Thus, the method of FIG. 4 provides for an engine control
method, comprising: deactivating an engine cylinder in response to
an engine temperature exceeding a threshold temperature; and
adjusting an amount of lift of an intake valve of the engine
cylinder in response to the engine temperature exceeding the
threshold temperature. The method further comprises adjusting an
opening or closing time of the intake valve in response to the
engine temperature exceeding the threshold temperature. The method
further comprises deactivating one or more additional engine
cylinders in response to the engine temperature exceeding the
threshold temperature. The method includes where the engine
cylinder is deactivated via ceasing fuel flow to the cylinder. The
method further comprises reducing an engine torque limit in
response to the engine temperature exceeding the threshold
temperature. The method further comprises delivering a driver
demand torque via activated cylinders after deactivating the engine
cylinder. The method further comprises deactivating cylinder
deactivation in response to the actual total number of valve
operator state changes being greater than a third threshold.
[0052] The method of FIG. 4 also provides for an engine control
method, comprising: deactivating one or more cylinders of a
plurality of cylinders of an engine in response to an engine
temperature exceeding a threshold temperature; adjusting which of
the plurality of cylinders is deactivated while the engine
temperature exceeds the threshold temperature; and adjusting air
flow through the deactivated one or more cylinders as a function of
the engine temperature. The method includes where adjusting air
flow though the deactivated one or more cylinders includes
adjusting an amount of valve lift of intake valves of the
deactivated one or more cylinders. The method includes where
adjusting air flow though the deactivated one or more cylinders
includes adjusting an opening or closing timing of intake valves of
the deactivated one or more cylinders. The method includes where
adjusting air flow through the deactivated one or more cylinders
includes adjusting a position of a throttle. The method further
comprises adjusting air flow through activated cylinders included
in the plurality of cylinders based on a driver demand torque. The
method includes where adjusting which of the plurality of cylinders
is deactivated includes changing which of the plurality of
cylinders is deactivated between two engine cycles.
[0053] Note that the example control and estimation routines
included herein can be used with various engine and/or vehicle
system configurations. 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, at least a portion of 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 control system. The control actions may also
transform the operating state of one or more sensors or actuators
in the physical world when the described actions are carried out by
executing the instructions in a system including the various engine
hardware components in combination with one or more
controllers.
[0054] This concludes the description. The reading of it by those
skilled in the art would bring to mind many alterations and
modifications without departing from the spirit and the scope of
the description. For example, I3, I4, I5, V6, V8, V10, and V12
engines operating in natural gas, gasoline, diesel, or alternative
fuel configurations could use the present description to
advantage.
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