Title of Invention	VEHICLE WITH IMPROVED ENGINE EFFICIENCY BASED ON CAMSHAFT PROFILE
Abstract	A vehicle may include a drive axle, an engine assembly, a coupling device, and an engine load management system. The engine assembly may include a valvetrain including a fixed-lobe camshaft and intake and exhaust valves supported by the engine assembly. The fixed-lobe camshaft may include a first lobe engaged with the intake valve to open the intake valve and a second lobe engaged with the exhaust valve to open the exhaust valve. The first and second lobes may be fixed relative to one another to define a constant valve overlap condition that provides for opening of the intake valve before the exhaust valve is fully closed, creating an engine operating condition that results in combustion instability below an engine load limit. The engine load management system may be in communication with the engine to prevent engine operation below the engine load limit.

Title of Invention

VEHICLE WITH IMPROVED ENGINE EFFICIENCY BASED ON CAMSHAFT PROFILE

Abstract

A vehicle may include a drive axle, an engine assembly, a coupling device, and an engine load management system. The engine assembly may include a valvetrain including a fixed-lobe camshaft and intake and exhaust valves supported by the engine assembly. The fixed-lobe camshaft may include a first lobe engaged with the intake valve to open the intake valve and a second lobe engaged with the exhaust valve to open the exhaust valve. The first and second lobes may be fixed relative to one another to define a constant valve overlap condition that provides for opening of the intake valve before the exhaust valve is fully closed, creating an engine operating condition that results in combustion instability below an engine load limit. The engine load management system may be in communication with the engine to prevent engine operation below the engine load limit.

Full Text	HIGH OVERLAP CAMSHAFT FOR IMPROVED ENGINE EFFICIENCY FIELD [0001] The present disclosure relates to camshaft profiles, and more specifically to improving engine efficiency in vehicles based on camshaft profiles and engine load. BACKGROUND [0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. [0003] Engine assemblies typically include one or more camshafts that actuate intake and exhaust valves. Providing an overlap between intake and exhaust valve opening may provide efficiency gains at partial engine load conditions and power gains at high engine load conditions. However, the amount of overlap is limited by low engine load conditions due to combustion stability concerns, especially at low engine speeds. SUMMARY [0004] A vehicle may include a drive axle, an engine assembly, a coupling device, and an engine load management system. The engine assembly may include an engine block that defines a cylinder, a piston disposed within the cylinder, a crankshaft rotatably driven by the piston, and a valvetrain including a fixed-lobe camshaft and intake and exhaust valves supported by the engine assembly. The intake and exhaust valves may be in communication with the cylinder. The fixed-lobe camshaft may include a first lobe engaged with the intake valve to open the intake valve and a second lobe engaged with the exhaust valve to open the exhaust valve. The first and second lobes may be fixed relative to one another to define a constant valve overlap condition that provides for opening of the intake valve before the exhaust valve is fully closed. The duration of the valve overlap condition may create an engine operating condition that results in combustion instability when the engine is operated below an engine load limit. The engine load management system may be in communication with the engine to prevent engine operation below the engine load limit. [0005] A method may include providing a valve overlap condition between intake and exhaust valves for a cylinder of an engine that results in combustion instability when the engine is operated below an engine load limit. A vehicle associated with the engine may be operated in a first operating mode when a load applied to the engine to propel the vehicle is greater than the engine load limit. The method may further include determining when a load applied to the engine to propel the vehicle is below the engine load limit and operating the vehicle in a second operating mode when the load applied to the engine to propel the vehicle is below the engine load limit. The second operating mode may include applying a supplemental load to the engine to prevent operation below the engine load limit. [0006] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS [0007] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. [0008] Figure 1 is a schematic illustration of a vehicle according to the present disclosure; and [0009] Figure 2 is a schematic illustration of a camshaft of the vehicle shown in Figure 1. DETAILED DESCRIPTION [0010] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. [0011] Referring now to Figure 1, an exemplary vehicle 10 is schematically illustrated. The vehicle 10 may include an engine assembly 12, an optional hybrid power assembly 14, a transmission 16, and a drive axle 18. The engine assembly 12 may include an internal combustion engine 20. [0012] The engine 20 may include an engine block 24 that defines a plurality of cylinders 36, a piston 38 disposed within each of the cylinders 36, a crankshaft 40 in driven engagement with the pistons 38, and a valvetrain assembly 42. The valvetrain assembly 42 may include first and second camshafts 44, 46 and exhaust and intake valves 48, 50 associated with each of the cylinders 36. The first and second camshafts 44, 46 may be generally similar to one another. Therefore, the first camshaft 44 will be discussed with the understanding that the description applies equally to the second camshaft 46. While the engine 20 is shown as an overhead cam engine, it is understood that the present disclosure may additionally apply to other engine configurations such as cam-in-block engines. [0013] The first camshaft 44 may include a fixed-lobe camshaft having exhaust and intake lobes 52, 54 that are fixed for rotation with one another. The exhaust lobes 52 may be engaged with the exhaust valves 48 and the intake lobes 54 may be engaged with the intake valves 50 to open the exhaust and intake valves 48, 50. With reference to Figure 2, the pair of exhaust and intake lobes 52, 54 for each cylinder 36 may be orientated relative to one another to provide an overlap between the opening of the exhaust and intake valves 48, 50 for the cylinder 36. For example, the exhaust lobe 52 may have a first peak 56 and the intake lobe 54 may have a second peak 58. The first peak 56 may be rotationally offset from the the second peak 58 in rotational direction (R) by an angle (8). The angle (6) may be less than an angle needed to maintain combustion stability at engine loads below an engine load limit. [0014] The engine load limit may generally correspond to a light load, where the overlap between the opening of the exhaust and intake valves 48, 50 may allow recirculation of an unacceptable residual mass fraction from the exhaust gas. The high residual mass fraction may slow down the combustion process and lead to combustion instability. For example, stationary vehicle, vehicle coasting, and low-load cruise conditions may correspond to engine loads required to propel the vehicle 10 that are below the engine load limit. Stationary vehicle conditions may generally correspond to a normal idle condition for a vehicle. Engine brake torque values of approximately zero or less may additionally correspond to engine load conditions below the engine load limit. [0015] By way of non-limiting example, the hybrid power assembly 14 may prevent engine operation below the engine load limit and may include an electric motor 62 and a rechargeable battery 64. The electric motor 62 and the rechargeable battery 64 may form a drive mechanism for the hybrid power assembly 14. The motor 62 may be in electrical communication with the battery 64 to convert power from the battery 64 to mechanical power. The motor 62 may additionally be powered by the engine 20 and operated as a generator to provide power to charge the battery 64. The hybrid power assembly 14 may be incorporated into and engaged with the transmission 16. The motor 62 may be coupled to the output shaft 74 to power rotation of the drive axle 18 via the transmission 16. [0016] The engine assembly 12 may be coupled to the transmission 16 via a coupling device 72 and may drive the transmission 16. The coupling device 72 may include a friction clutch or a torque converter. The transmission 16 may use the power provided from the engine 20 and/or the motor 62 to drive the output shaft 74 and power rotation of the drive axle 18. [0017] In a first operating mode, the crankshaft 40 may drive the output shaft 74 through combustion within the cylinders 36. In a second operating mode, the engine 20 may be decoupled from the transmission 16 and the electric motor 62 may drive the output shaft 74. The engine 20 may be shut off during the second operating mode. In a third operating mode, the engine 20 may drive the electric motor 62 to charge the battery 64 and may drive the output shaft 74. Alternatively, when the battery 64 has a charge level greater than a predetermined level, a fourth operating mode may be provided where the electric motor 62 and the engine 20 both drive the output shaft 74. The combination of the normal engine operating load and the load applied by the electric motor 62 during the third operating mode may provide a total engine load during the third operating mode that is greater than the engine load limit. [0018] The exhaust and intake valves 48, 50 may optionally be part of a cylinder deactivation system (not shown) where the exhaust and intake valves 48, 50 associated with a portion of the cylinders 36 are not operated. The hybrid power assembly 14 and the cylinder deactivation system may be used in combination or independently from one another to form an engine load management system for the vehicle 10. It is understood that the engine load management system is not limited to the hybrid power assembly 14 or the cylinder deactivation system and that various alternate load management mechanisms may be used while remaining within the scope of the present disclosure. For example, in the engine 20 shown in Figure 1, the exhaust and intake valves 48, 50 associated with one-half (four) of the cylinders 36 may be inoperable when operated in a cylinder-deactivation mode. The engine 20 may be operated in the cylinder deactivation mode to increase a net load on the firing cylinders. The increased net load may be greater than the engine load limit. The engine assembly 12 may further include cam phasers 60, 61 for the first and second camshafts 44, 46. The cam phasers 60, 61 may include dual-equal phasers since the exhaust and intake lobes 52, 54 may be fixed for rotation with one another. Therefore, when the first and second camshafts 44, 46 are advanced or retarded, the exhaust and intake lobes 52, 54 move with one another. Further, it is understood that the teachings of the present disclosure may apply to concentric camshaft designs as well, where intake and exhaust lobes are rotatable relative to one another. [0019] The overlap of the opening of the exhaust and intake valves 48, 50 may increase the power output of the engine 20 when the engine 20 is operated above the engine load limit at full load conditions. The overlap may also increase the fuel economy and/or reduce emissions at part load conditions. The power output, efficiency, and emissions gains may be relative to an engine having a camshaft with intake and exhaust lobes that provide an opening overlap that provides combustion stability at engine loads below the engine load limit discussed above. [0020] During operation, the engine 20 may either be shut off or may experience an additional load from the engine load management system during periods when the engine 20 would typically experience engine loads below the engine load limit. As discussed above, the engine load management system may include the hybrid power assembly 14 and/or the cylinder deactivation system. For example, when the engine 20 would typically experience a load that is less than the engine load limit, an additional load may be applied to the engine 20 by operating the engine 20 in the third operating mode and/or operating the engine 20 in a cylinder deactivation mode to increase the engine load on the activated cylinders to a level greater than the engine load limit. Alternatively, the engine 20 may be shut off during periods when the operating load would be less than the engine load limit When the engine 20 is shut off, the electric motor 62 may power the vehicle 10. CLAIMS What is claimed is: 1. A vehicle comprising: a drive axle; an engine assembly including: an engine block defining a cylinder; a piston disposed within the cylinder; a crankshaft rotatably driven by the piston; and a valvetrain including a fixed-lobe camshaft and intake and exhaust valves supported by the engine assembly, the intake and exhaust valves being in communication with the cylinder and the fixed-lobe camshaft including a first lobe engaged with the intake valve to open the intake valve and a second lobe engaged with the exhaust valve to open the exhaust valve, the first and second lobes being fixed relative to one another to define a constant valve overlap condition that provides for opening of the intake valve before the exhaust valve is fully closed, a duration of the valve overlap condition creating an engine operating condition that results in combustion instability when the engine is operated below an engine load limit; and an engine load management system in communication with the engine to prevent engine operation below the engine load limit. 2. The vehicle of claim 1, wherein the engine load management system includes a coupling device and a hybrid drive assembly, the coupling device providing engagement between the crankshaft and the drive axle during a first operating mode and disengaging the crankshaft from the drive axle during a second operating mode, the hybrid drive assembly including a drive mechanism engaged with one of the drive axle and the crankshaft to prevent engine operation below the engine load limit. 3. The vehicle of claim 2, wherein the drive mechanism is engaged with the crankshaft during the first operating mode to apply an additional load to the engine and increase a total load on the engine to a level greater than the engine load limit. 4. The vehicle of claim 3, wherein the drive mechanism includes an electric motor and a battery in electrical communication with the electric motor, the crankshaft driving the electric motor to charge the battery during the first operating mode. 5. The vehicle of claim 4, wherein the first operating mode corresponds to an engine idle condition. 6. The vehicle of claim 2, wherein the second operating mode corresponds to an engine load that is less than the engine load limit, the engine being shut off during the second operating mode and the drive mechanism being engaged with the drive shaft to power the vehicle. 7. The vehicle of claim 6, wherein the second operating mode corresponds to a vehicle coasting condition. 8. The vehicle of claim 6, wherein the second operating mode corresponds to a stationary vehicle condition. 9. The vehicle of claim 1, wherein a level of exhaust gas remaining in the cylinder from the valve overlap condition creates the combustion instability. 10. The vehicle of claim 1, wherein the engine block defines at least two cylinders, the engine load management system including a cylinder deactivation system formed by the valvetrain and operable in a full cylinder mode and a deactivated mode where at least one of the cylinders is deactivated to create an increased load on the remaining cylinders, the engine assembly being operated in the deactivated mode to maintain an engine load above the engine load limit. 11. The vehicle of claim 10, wherein the engine load management system includes a coupling device and a hybrid drive assembly, the coupling device providing engagement between the crankshaft and the drive axle during a first operating mode and disengaging the crankshaft from the drive axle during a second operating mode, the hybrid drive assembly including a drive mechanism engaged with one of the drive axle and the crankshaft to prevent engine operation below the engine load limit, the engine assembly being operated in the deactivated mode during the first operating mode. 12. The vehicle of claim 10, wherein the engine assembly is operated in the deactivated mode during a stationary vehicle condition to maintain an engine load above the engine load limit. 13. The vehicle of claim 10, wherein the engine assembly is operated in the deactivated mode during a vehicle coasting condition to maintain an engine load above the engine load limit. 14. A method comprising: providing a valve overlap condition between intake and exhaust valves for a cylinder of an engine that results in combustion instability when the engine is operated below an engine load limit; operating a vehicle associated with the engine in a first operating mode when a load applied to the engine to propel the vehicle is greater than the engine load limit; determining when a load applied to the engine to propel the vehicle is below the engine load limit; and operating the vehicle in a second operating mode when the load applied to the engine to propel the vehicle is below the engine load limit, the second operating mode including applying a supplemental load to the engine to prevent operation below the engine load limit. 15. The method of claim 14, wherein the vehicle is a hybrid vehicle including a drive mechanism and further comprising shutting off the engine and engaging the drive mechanism with a drive axle of the vehicle to propel the vehicle when the load applied to the engine to propel the vehicle is below the engine load limit. 16. The method of claim 14, wherein the vehicle is a hybrid vehicle including a drive mechanism and the second operating mode includes engaging the drive mechanism with a crankshaft of the engine to apply the supplemental load to the engine. 17. The method of claim 16, wherein the hybrid vehicle includes an electric motor and a battery in communication with the electric motor, the crankshaft driving the electric motor to charge the battery during the second operating mode. 18. The method of claim 14, wherein the engine defines at least two cylinders and includes a valvetrain forming a cylinder deactivation system operable in a full cylinder mode and a deactivated mode where at least one of the cylinders is deactivated to create an increased load on the remaining cylinders, the second operating mode including operating the engine in the deactivated mode to maintain an engine load above the engine load limit. 19. The method of claim 14, wherein the second operating mode corresponds to a vehicle coasting condition. 20. The method of claim 14, wherein the second operating mode corresponds to a stationary vehicle condition. A vehicle may include a drive axle, an engine assembly, a coupling device, and an engine load management system. The engine assembly may include a valvetrain including a fixed-lobe camshaft and intake and exhaust valves supported by the engine assembly. The fixed-lobe camshaft may include a first lobe engaged with the intake valve to open the intake valve and a second lobe engaged with the exhaust valve to open the exhaust valve. The first and second lobes may be fixed relative to one another to define a constant valve overlap condition that provides for opening of the intake valve before the exhaust valve is fully closed, creating an engine operating condition that results in combustion instability below an engine load limit. The engine load management system may be in communication with the engine to prevent engine operation below the engine load limit.

Full Text

HIGH OVERLAP CAMSHAFT FOR IMPROVED ENGINE EFFICIENCY
FIELD
[0001] The present disclosure relates to camshaft profiles, and more
specifically to improving engine efficiency in vehicles based on camshaft profiles
and engine load.
BACKGROUND
[0002] The statements in this section merely provide background
information related to the present disclosure and may not constitute prior art.
[0003] Engine assemblies typically include one or more camshafts that
actuate intake and exhaust valves. Providing an overlap between intake and
exhaust valve opening may provide efficiency gains at partial engine load
conditions and power gains at high engine load conditions. However, the amount
of overlap is limited by low engine load conditions due to combustion stability
concerns, especially at low engine speeds.
SUMMARY
[0004] A vehicle may include a drive axle, an engine assembly, a
coupling device, and an engine load management system. The engine assembly
may include an engine block that defines a cylinder, a piston disposed within the
cylinder, a crankshaft rotatably driven by the piston, and a valvetrain including a
fixed-lobe camshaft and intake and exhaust valves supported by the engine
assembly. The intake and exhaust valves may be in communication with the

cylinder. The fixed-lobe camshaft may include a first lobe engaged with the
intake valve to open the intake valve and a second lobe engaged with the
exhaust valve to open the exhaust valve. The first and second lobes may be
fixed relative to one another to define a constant valve overlap condition that
provides for opening of the intake valve before the exhaust valve is fully closed.
The duration of the valve overlap condition may create an engine operating
condition that results in combustion instability when the engine is operated below
an engine load limit. The engine load management system may be in
communication with the engine to prevent engine operation below the engine
load limit.
[0005] A method may include providing a valve overlap condition
between intake and exhaust valves for a cylinder of an engine that results in
combustion instability when the engine is operated below an engine load limit. A
vehicle associated with the engine may be operated in a first operating mode
when a load applied to the engine to propel the vehicle is greater than the engine
load limit. The method may further include determining when a load applied to
the engine to propel the vehicle is below the engine load limit and operating the
vehicle in a second operating mode when the load applied to the engine to propel
the vehicle is below the engine load limit. The second operating mode may
include applying a supplemental load to the engine to prevent operation below
the engine load limit.
[0006] Further areas of applicability will become apparent from the
description provided herein. It should be understood that the description and

specific examples are intended for purposes of illustration only and are not
intended to limit the scope of the present disclosure.
DRAWINGS
[0007] The drawings described herein are for illustration purposes only
and are not intended to limit the scope of the present disclosure in any way.
[0008] Figure 1 is a schematic illustration of a vehicle according to the
present disclosure; and
[0009] Figure 2 is a schematic illustration of a camshaft of the vehicle
shown in Figure 1.
DETAILED DESCRIPTION
[0010] The following description is merely exemplary in nature and is
not intended to limit the present disclosure, application, or uses. It should be
understood that throughout the drawings, corresponding reference numerals
indicate like or corresponding parts and features.
[0011] Referring now to Figure 1, an exemplary vehicle 10 is
schematically illustrated. The vehicle 10 may include an engine assembly 12, an
optional hybrid power assembly 14, a transmission 16, and a drive axle 18. The
engine assembly 12 may include an internal combustion engine 20.
[0012] The engine 20 may include an engine block 24 that defines a
plurality of cylinders 36, a piston 38 disposed within each of the cylinders 36, a
crankshaft 40 in driven engagement with the pistons 38, and a valvetrain

assembly 42. The valvetrain assembly 42 may include first and second
camshafts 44, 46 and exhaust and intake valves 48, 50 associated with each of
the cylinders 36. The first and second camshafts 44, 46 may be generally similar
to one another. Therefore, the first camshaft 44 will be discussed with the
understanding that the description applies equally to the second camshaft 46.
While the engine 20 is shown as an overhead cam engine, it is understood that
the present disclosure may additionally apply to other engine configurations such
as cam-in-block engines.
[0013] The first camshaft 44 may include a fixed-lobe camshaft having
exhaust and intake lobes 52, 54 that are fixed for rotation with one another. The
exhaust lobes 52 may be engaged with the exhaust valves 48 and the intake
lobes 54 may be engaged with the intake valves 50 to open the exhaust and
intake valves 48, 50. With reference to Figure 2, the pair of exhaust and intake
lobes 52, 54 for each cylinder 36 may be orientated relative to one another to
provide an overlap between the opening of the exhaust and intake valves 48, 50
for the cylinder 36. For example, the exhaust lobe 52 may have a first peak 56
and the intake lobe 54 may have a second peak 58. The first peak 56 may be
rotationally offset from the the second peak 58 in rotational direction (R) by an
angle (8). The angle (6) may be less than an angle needed to maintain
combustion stability at engine loads below an engine load limit.
[0014] The engine load limit may generally correspond to a light load,
where the overlap between the opening of the exhaust and intake valves 48, 50
may allow recirculation of an unacceptable residual mass fraction from the

exhaust gas. The high residual mass fraction may slow down the combustion
process and lead to combustion instability. For example, stationary vehicle,
vehicle coasting, and low-load cruise conditions may correspond to engine loads
required to propel the vehicle 10 that are below the engine load limit. Stationary
vehicle conditions may generally correspond to a normal idle condition for a
vehicle. Engine brake torque values of approximately zero or less may
additionally correspond to engine load conditions below the engine load limit.
[0015] By way of non-limiting example, the hybrid power assembly 14
may prevent engine operation below the engine load limit and may include an
electric motor 62 and a rechargeable battery 64. The electric motor 62 and the
rechargeable battery 64 may form a drive mechanism for the hybrid power
assembly 14. The motor 62 may be in electrical communication with the battery
64 to convert power from the battery 64 to mechanical power. The motor 62 may
additionally be powered by the engine 20 and operated as a generator to provide
power to charge the battery 64. The hybrid power assembly 14 may be
incorporated into and engaged with the transmission 16. The motor 62 may be
coupled to the output shaft 74 to power rotation of the drive axle 18 via the
transmission 16.
[0016] The engine assembly 12 may be coupled to the transmission 16
via a coupling device 72 and may drive the transmission 16. The coupling device
72 may include a friction clutch or a torque converter. The transmission 16 may
use the power provided from the engine 20 and/or the motor 62 to drive the
output shaft 74 and power rotation of the drive axle 18.

[0017] In a first operating mode, the crankshaft 40 may drive the output
shaft 74 through combustion within the cylinders 36. In a second operating
mode, the engine 20 may be decoupled from the transmission 16 and the electric
motor 62 may drive the output shaft 74. The engine 20 may be shut off during
the second operating mode. In a third operating mode, the engine 20 may drive
the electric motor 62 to charge the battery 64 and may drive the output shaft 74.
Alternatively, when the battery 64 has a charge level greater than a
predetermined level, a fourth operating mode may be provided where the electric
motor 62 and the engine 20 both drive the output shaft 74. The combination of
the normal engine operating load and the load applied by the electric motor 62
during the third operating mode may provide a total engine load during the third
operating mode that is greater than the engine load limit.
[0018] The exhaust and intake valves 48, 50 may optionally be part of
a cylinder deactivation system (not shown) where the exhaust and intake valves
48, 50 associated with a portion of the cylinders 36 are not operated. The hybrid
power assembly 14 and the cylinder deactivation system may be used in
combination or independently from one another to form an engine load
management system for the vehicle 10. It is understood that the engine load
management system is not limited to the hybrid power assembly 14 or the
cylinder deactivation system and that various alternate load management
mechanisms may be used while remaining within the scope of the present
disclosure. For example, in the engine 20 shown in Figure 1, the exhaust and
intake valves 48, 50 associated with one-half (four) of the cylinders 36 may be

inoperable when operated in a cylinder-deactivation mode. The engine 20 may
be operated in the cylinder deactivation mode to increase a net load on the firing
cylinders. The increased net load may be greater than the engine load limit. The
engine assembly 12 may further include cam phasers 60, 61 for the first and
second camshafts 44, 46. The cam phasers 60, 61 may include dual-equal
phasers since the exhaust and intake lobes 52, 54 may be fixed for rotation with
one another. Therefore, when the first and second camshafts 44, 46 are
advanced or retarded, the exhaust and intake lobes 52, 54 move with one
another. Further, it is understood that the teachings of the present disclosure
may apply to concentric camshaft designs as well, where intake and exhaust
lobes are rotatable relative to one another.
[0019] The overlap of the opening of the exhaust and intake valves 48,
50 may increase the power output of the engine 20 when the engine 20 is
operated above the engine load limit at full load conditions. The overlap may
also increase the fuel economy and/or reduce emissions at part load conditions.
The power output, efficiency, and emissions gains may be relative to an engine
having a camshaft with intake and exhaust lobes that provide an opening overlap
that provides combustion stability at engine loads below the engine load limit
discussed above.
[0020] During operation, the engine 20 may either be shut off or may
experience an additional load from the engine load management system during
periods when the engine 20 would typically experience engine loads below the
engine load limit. As discussed above, the engine load management system

may include the hybrid power assembly 14 and/or the cylinder deactivation
system. For example, when the engine 20 would typically experience a load that
is less than the engine load limit, an additional load may be applied to the engine
20 by operating the engine 20 in the third operating mode and/or operating the
engine 20 in a cylinder deactivation mode to increase the engine load on the
activated cylinders to a level greater than the engine load limit. Alternatively, the
engine 20 may be shut off during periods when the operating load would be less
than the engine load limit When the engine 20 is shut off, the electric motor 62
may power the vehicle 10.

CLAIMS
What is claimed is:
1. A vehicle comprising:
a drive axle;
an engine assembly including:
an engine block defining a cylinder;
a piston disposed within the cylinder;
a crankshaft rotatably driven by the piston; and
a valvetrain including a fixed-lobe camshaft and intake and
exhaust valves supported by the engine assembly, the intake and exhaust valves
being in communication with the cylinder and the fixed-lobe camshaft including a
first lobe engaged with the intake valve to open the intake valve and a second
lobe engaged with the exhaust valve to open the exhaust valve, the first and
second lobes being fixed relative to one another to define a constant valve
overlap condition that provides for opening of the intake valve before the exhaust
valve is fully closed, a duration of the valve overlap condition creating an engine
operating condition that results in combustion instability when the engine is
operated below an engine load limit; and
an engine load management system in communication with the
engine to prevent engine operation below the engine load limit.

2. The vehicle of claim 1, wherein the engine load management
system includes a coupling device and a hybrid drive assembly, the coupling
device providing engagement between the crankshaft and the drive axle during a
first operating mode and disengaging the crankshaft from the drive axle during a
second operating mode, the hybrid drive assembly including a drive mechanism
engaged with one of the drive axle and the crankshaft to prevent engine
operation below the engine load limit.
3. The vehicle of claim 2, wherein the drive mechanism is engaged
with the crankshaft during the first operating mode to apply an additional load to
the engine and increase a total load on the engine to a level greater than the
engine load limit.
4. The vehicle of claim 3, wherein the drive mechanism includes an
electric motor and a battery in electrical communication with the electric motor,
the crankshaft driving the electric motor to charge the battery during the first
operating mode.
5. The vehicle of claim 4, wherein the first operating mode
corresponds to an engine idle condition.

6. The vehicle of claim 2, wherein the second operating mode
corresponds to an engine load that is less than the engine load limit, the engine
being shut off during the second operating mode and the drive mechanism being
engaged with the drive shaft to power the vehicle.
7. The vehicle of claim 6, wherein the second operating mode
corresponds to a vehicle coasting condition.
8. The vehicle of claim 6, wherein the second operating mode
corresponds to a stationary vehicle condition.
9. The vehicle of claim 1, wherein a level of exhaust gas remaining in
the cylinder from the valve overlap condition creates the combustion instability.
10. The vehicle of claim 1, wherein the engine block defines at least
two cylinders, the engine load management system including a cylinder
deactivation system formed by the valvetrain and operable in a full cylinder mode
and a deactivated mode where at least one of the cylinders is deactivated to
create an increased load on the remaining cylinders, the engine assembly being
operated in the deactivated mode to maintain an engine load above the engine
load limit.

11. The vehicle of claim 10, wherein the engine load management
system includes a coupling device and a hybrid drive assembly, the coupling
device providing engagement between the crankshaft and the drive axle during a
first operating mode and disengaging the crankshaft from the drive axle during a
second operating mode, the hybrid drive assembly including a drive mechanism
engaged with one of the drive axle and the crankshaft to prevent engine
operation below the engine load limit, the engine assembly being operated in the
deactivated mode during the first operating mode.
12. The vehicle of claim 10, wherein the engine assembly is operated
in the deactivated mode during a stationary vehicle condition to maintain an
engine load above the engine load limit.
13. The vehicle of claim 10, wherein the engine assembly is operated
in the deactivated mode during a vehicle coasting condition to maintain an
engine load above the engine load limit.

14. A method comprising:
providing a valve overlap condition between intake and exhaust
valves for a cylinder of an engine that results in combustion instability when the
engine is operated below an engine load limit;
operating a vehicle associated with the engine in a first operating
mode when a load applied to the engine to propel the vehicle is greater than the
engine load limit;
determining when a load applied to the engine to propel the vehicle
is below the engine load limit; and
operating the vehicle in a second operating mode when the load
applied to the engine to propel the vehicle is below the engine load limit, the
second operating mode including applying a supplemental load to the engine to
prevent operation below the engine load limit.
15. The method of claim 14, wherein the vehicle is a hybrid vehicle
including a drive mechanism and further comprising shutting off the engine and
engaging the drive mechanism with a drive axle of the vehicle to propel the
vehicle when the load applied to the engine to propel the vehicle is below the
engine load limit.

16. The method of claim 14, wherein the vehicle is a hybrid vehicle
including a drive mechanism and the second operating mode includes engaging
the drive mechanism with a crankshaft of the engine to apply the supplemental
load to the engine.
17. The method of claim 16, wherein the hybrid vehicle includes an
electric motor and a battery in communication with the electric motor, the
crankshaft driving the electric motor to charge the battery during the second
operating mode.
18. The method of claim 14, wherein the engine defines at least two
cylinders and includes a valvetrain forming a cylinder deactivation system
operable in a full cylinder mode and a deactivated mode where at least one of
the cylinders is deactivated to create an increased load on the remaining
cylinders, the second operating mode including operating the engine in the
deactivated mode to maintain an engine load above the engine load limit.
19. The method of claim 14, wherein the second operating mode
corresponds to a vehicle coasting condition.
20. The method of claim 14, wherein the second operating mode
corresponds to a stationary vehicle condition.

A vehicle may include a drive axle, an engine assembly, a coupling
device, and an engine load management system. The engine assembly may
include a valvetrain including a fixed-lobe camshaft and intake and exhaust
valves supported by the engine assembly. The fixed-lobe camshaft may include
a first lobe engaged with the intake valve to open the intake valve and a second
lobe engaged with the exhaust valve to open the exhaust valve. The first and
second lobes may be fixed relative to one another to define a constant valve
overlap condition that provides for opening of the intake valve before the exhaust
valve is fully closed, creating an engine operating condition that results in
combustion instability below an engine load limit. The engine load management
system may be in communication with the engine to prevent engine operation
below the engine load limit.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=2FCzLOajF+/0P/ngPfIjqg==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

277940

Indian Patent Application Number

451/KOL/2009

PG Journal Number

51/2016

Publication Date

09-Dec-2016

Grant Date

06-Dec-2016

Date of Filing

13-Mar-2009

Name of Patentee

GM GLOBAL TECHNOLOGY OPERATIONS, INC.

Applicant Address

300 GM RENAISSANCE CENTER DETROIT, MICHIGAN 48265-3000

Inventors:

#	Inventor's Name	Inventor's Address
1	RICHARD STEPHEN DAVIS	1059 PARKLAND ROAD, LAKE ORION, MI 48360
2	GARY J. PATTERSON	45823 CASS AVENUE UTICA MICHIGAN 48317
3	RONALD J HERRIN	2859 CREEK BEND DRIVE, TROY, MICHIGAN 48098

PCT International Classification Number

B60K6/20; F02D13/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	12/103304	2008-04-15	U.S.A.