Title of Invention

AN APPARATUS AND METHOD TO CONTROL TORQUE OUTPUT FORM A TRANSMISSION DEVICE DURING A GEAR-TO-GEAR SHIFTING EVENT

Abstract A control system is provided to effect a method to control torque output from a two-mode, compound-split, electro-mechanical transmission during gear-to-gear shifting event when an off-going torque-transfer device is disengaged. It includes a computer program which controls transmission operation. A predetermined preferred torque output from the transmission device is determined. Torque output from torque-generative devices device is controlled. Torque transmitted across a selectively actuated torque transfer device is controlled, and limited based upon available battery power. Actuation of the oncoming torque-transfer device is preferably based upon a temperature of the device during the shifting event. The temperature during the shifting event is determined based upon a rotational speed of an input shaft to the transmission and an elapsed time to shift.
Full Text 1
GP-307725
APPARATUS AND METHOD TO CONTROL TRANSMISSION TORQUE
OUTPUT DURING A GEAR-TO-GEAR SHIFT
TECHNICAL FIELD
[0001] This invention pertains generally to powertrain control systems for
fuel/electric hybrid powertrain systems, and more specifically to powertrain
control during transmission shifts.
BACKGROUND OF THE INVENTION
[0002] Various hybrid powertrain architectures are known for managing the
input and output torques of various torque-generative devices in hybrid
vehicles, most commonly internal combustion engines and electric machines.
One such hybrid powertrain architecture comprises a two-mode, compound-
split, electro-mechanical transmission which utilizes an input member for
receiving motive torque from a prime mover power source, typically an
internal combustion engine, and an output member for delivering motive
torque from the transmission to a driveline of the vehicle. First and second
electrical machines are operatively connected to an electrical energy storage
device for interchanging electrical power therebetween. The first and second
electrical machines comprise motor/generators operable to transform the
electrical power to motive torque for input to the transmission, independently
of torque input from the internal combustion engine. The first and second
electrical machines are further operable to transform vehicle kinetic energy,
transmitted through the vehicle driveline, to electrical energy potential that is
storable in the electrical energy storage device. A control unit is provided for
regulating the electrical power interchange between the electrical energy
storage device and the first and second electrical machines.
[0003] Engineers implementing powertrain systems including transmissions
are tasked with developing gear shifting schemes. Such transmission systems
typically include devices able to operate in one of a plurality of fixed-gear

2
modes, wherein shifting between the fixed gears occurs in response to
predetermined operating conditions, and often not involving an overt request
for shift from a vehicle operator.
[0004] In fixed gear operation, the internal combustion engine operates by
providing an input speed and torque to the transmission device. The
transmission input speed is equal to transmission output speed multiplied by
the initial fixed gear ratio. When a shift is commanded, torque is off-loaded
from a currently applied clutch. When an oncoming clutch is applied, the
transmission input speed, coming from the internal combustion engine, needs
to match the transmission output speed multiplied by the oncoming gear ratio.
When the input speed from the engine does not match the transmission output
speed multiplied by the oncoming gear ratio, driveline jerks, clutch slippage,
and other problems leading to customer dissatisfaction occur. Furthermore,
such actions as driveline jerks and clutch slippage may affect operating
temperatures of the transmission clutches, and therefore clutch durability. On
a hybrid powertrain system having a plurality of torque-generative devices,
there are additional variables and degrees of freedom affecting operation of
the powertrain which must be considered and managed during shift operation.
[0005] Therefore, there is a need to for a method and apparatus to control
powertrain operation during gear shifting events for a hybrid powertrain
system, to address concerns mentioned hereinabove.
SUMMARY OF THE INVENTION
[0006] In order to address the concerns raised hereinabove, an article of
manufacture is provided to effect a method to control torque output from a
transmission device of an exemplary powertrain during a gear-to-gear shifting
event when an off-going torque-transfer device is disengaged.
[0007] In accordance with the present invention, the exemplary powertrain
system comprises a plurality of torque-generative devices each operable to
supply motive torque to the transmission device and vehicle driveline, and the
exemplary transmission device comprises a two-mode, compound-split, hybrid

3
electro-mechanical transmission having four fixed gear ratios. There is a
plurality of gears operable to transmit torque between the transmission device
and an output shaft using a plurality of torque-transfer devices. The torque-
generative devices preferably comprise a pair of electrical machines and an
internal combustion engine. Torque transmission can be in the form of
transmitting motive torque from one of the torque-generative devices through
the transmission to the vehicle driveline.
[0008] An aspect of the invention includes the aforementioned article of
manufacture comprising a storage medium having a computer program
encoded therein for effecting the method, wherein the storage medium is
integrated in an electronic control system. The method is preferably executed
as a computer program in a distributed electronic control system which
controls operation of the transmission. The method first comprises a
predetermined preferred torque output from the transmission device. Torque
output from each of a plurality of torque-generative devices operative to
transmit motive torque to the transmission device is controlled during the shift.
Torque transmitted across a selectively actuated torque transfer device is
controlled preferably to substantially meet the predetermined preferred torque
output from the transmission device.
[0009] An aspect of the invention includes the transmission comprising a
two-mode, compound-split, electro-mechanical transmission, wherein the
torque-generative devices comprise electrical machines. The motive torque
output from the electrical machines operative to transmit motive torque to the
transmission device is limited based upon available battery power. The
electrical machines are each operable to independently transmit motive torque
to the transmission.
[0010] Another aspect of the invention comprises the transmission device
including four torque-transfer devices operative to control the transmission in
operating ranges of at least four fixed-gear modes and two continuously
variable modes.

4
[0011] Another aspect of the invention includes the torque-generative
devices further comprising an internal combustion engine.
[0012] Another aspect of the invention includes the transmission operable to
provide motive torque to a driveline of a vehicle.
[0013] Another aspect of the invention includes the predetermined preferred
torque output from the transmission device comprising a series of time-based
values for output torque derived based upon operator expectations during a
shifting event.
[0014] Another aspect of the invention includes controlling actuation of the
torque-transfer device based upon a temperature of the selectively actuated
torque-transfer device during the shifting event. The temperature of the
selectively actuated torque-transfer device during the shifting event is
determined based upon a rotational speed of an input shaft to the transmission
and an elapsed time to shift.
[0015] Another aspect of the invention includes controlling actuation of the
torque-transfer device based upon slippage of the selectively actuated torque-
transfer device during the shifting event. This includes controlling torque
transmitted across the selectively actuated torque transfer device based upon a
temperature of the torque transfer device during the shift event.
[0016] Another aspect of the invention includes determining the temperature
of the torque transfer device during the shift event based upon rotation of an
input shaft to the transmission and an elapsed time to shift.
[0017] These and other aspects of the invention will become apparent to
those skilled in the art upon reading and understanding the following detailed
description of the embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The invention may take physical form in certain parts and
arrangement of parts, the preferred embodiment of which will be described in
detail and illustrated in the accompanying drawings which form a part hereof,
and wherein:

5
[0019] Fig. 1 is a schematic diagram of an exemplary powertrain, in
accordance with the present invention;
[0020] Fig. 2 is a schematic diagram of an exemplary architecture for a
controller and powertrain, in accordance with the present invention; and,
[0021] Figs. 3A, 3B, and 3C comprise exemplary data graphs, in accordance
with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] Referring now to the drawings, wherein the showings are for the
purpose of illustrating the invention only and not for the purpose of limiting
the same, Figs. 1 and 2 show a system comprising an engine 14, transmission
10, control system, and driveline which has been constructed in accordance
with an embodiment of the present invention.
[0023] Mechanical aspects of exemplary transmission 10 are disclosed in
detail in commonly assigned U.S. Patent Application Publication No. U.S.
2005/0137042 Al, published June 23, 2005, entitled Two-Mode, Compound-
Split, Hybrid Electro-Mechanical Transmission having Four Fixed Ratios,
which is incorporated herein by reference. The exemplary two-mode,
compound-split, electro-mechanical hybrid transmission embodying the
concepts of the present invention is depicted in Fig. 1, and is designated
generally by the numeral 10. The transmission 10 has an input shaft 12 that is
preferably directly driven by an engine 14. A transient torque damper 20 is
incorporated between the output shaft 18 of the engine 14 and the input
member 12 of the transmission 10. The transient torque damper 20 preferably
comprises a torque transfer device 77 having characteristics of a damping
mechanism and a spring, shown respectively as 78 and 79. The transient
torque damper 20 permits selective engagement of the engine 14 with the
transmission 10, but it must be understood that the torque transfer device 77 is
not utilized to change, or control, the mode in which the transmission 10
operates. The torque transfer device 77 preferably comprises a hydraulically
operated friction clutch, referred to as clutch C5.

6
[0024] The engine 14 may be any of numerous forms of internal combustion
engines, such as a spark-ignition engine or a compression-ignition engine,
readily adaptable to provide a power output to the transmission 10 at a range
of operating speeds, from idle, at or near 600 revolutions per minute (RPM), to
over 6,000 RPM. Irrespective of the means by which the engine 14 is
connected to the input member 12 of the transmission 10, the input member 12
is connected to a planetary gear set 24 in the transmission 10.
[0025] Referring specifically now to Fig. 1, the transmission 10 utilizes three
planetary-gear sets 24, 26 and 28. The first planetary gear set 24 has an outer
ring gear member 30 which circumscribes an inner, or sun gear member 32. A
plurality of planetary gear members 34 is rotatably mounted on a carrier 36
such that each planetary gear member 34 meshingly engages both the outer
gear member 30 and the inner gear member 32.
[0026] The second planetary gear set 26 also has an outer ring gear member
38, which circumscribes an inner sun gear member 40. A plurality of planetary
gear members 42 is rotatably mounted on a carrier 44 such that each planetary
gear 42 meshingly engages both the outer gear member 38 and the inner gear
member 40.
[0027] The third planetary gear set 28 also has an outer ring gear member
46, which circumscribes an inner sun gear member 48. A plurality of planetary
gear members 50 is rotatably mounted on a carrier 52 such that each planetary
gear 50 meshingly engages both the outer gear member 46 and the inner gear
member 48.
[0028] The three planetary gear sets 24, 26 and 28 each comprise simple
planetary gear sets. Furthermore, the first and second planetary gear sets 24
and 26 are compounded in that the inner gear member 32 of the first planetary
gear set 24 is conjoined through a hub plate gear 54 to the outer gear member
38 of the second planetary gear set 26. The conjoined inner gear member 32 of
the first planetary gear set 24 and the outer gear member 38 of the second
planetary gear set 26 are connected to a first electrical machine comprising a
motor/generator 56, also referred to as "MG-A".

7
[0029] The planetary gear sets 24 and 26 are further compounded in that the
carrier 36 of the first planetary gear set 24 is conjoined through a shaft 60, to
the carrier 44 of the second planetary gear set 26. As such, carriers 36 and 44
of the first and second planetary gear sets 24 and 26, respectively, are
conjoined. The shaft 60 is also selectively connected to the carrier 52 of the
third planetary gear set 28, through a torque transfer device 62 which, as will
be hereinafter more fully explained, is employed to assist in the selection of
the operational modes of the transmission 10. The carrier 52 of the third
planetary gear set 28 is connected directly to the transmission output member
64.
[0030] In the embodiment described herein, wherein the transmission 10 is
used in a land vehicle, the output member 64 is operably connected to a
driveline comprising a gear box 90 or other torque transfer device which
provides a torque output to one or more vehicular axles 92 or half-shafts (not
shown). The axles 92, in turn, terminate in drive members 96. The drive
members 96 may be either front or rear wheels of the vehicle on which they
are employed, or they may be a drive gear of a track vehicle. The drive
members 96 may have some form of wheel brake 94 associated therewith.
The drive members each have a speed parameter, NWHL, comprising rotational
speed of each wheel 96 which is typically measurable with a wheel speed
sensor.
[0031] The inner gear member 40 of the second planetary gear set 26 is
connected to the inner gear member 48 of the third planetary gear set 28,
through a sleeve shaft 66 that circumscribes shaft 60. The outer gear member
46 of the third planetary gear set 28 is selectively connected to ground,
represented by the transmission housing 68, through a torque transfer device
70. Torque transfer device 70, as is also hereinafter explained, is also
employed to assist in the selection of the operational modes of the
transmission 10. The sleeve shaft 66 is also connected to a second electrical
machine comprising a motor/generator 72, referred to as MG-B.

8
[0032] All the planetary gear sets 24, 26 and 28 as well as MG-A and MG-B
56 and 72 are coaxially oriented, as about the axially disposed shaft 60. MG-
A and MG-B 56 and 72 are both of an annular configuration which permits
them to circumscribe the three planetary gear sets 24, 26 and 28 such that the
planetary gear sets 24, 26 and 28 are disposed radially inwardly of the MG-A
and MG-B 56 and 72. A resolver 80 is attached to each of the MG-A and MG-
B, as described hereinbelow.
[0033] A torque transfer device C3 73 selectively connects the sun gear 40
with ground, i.e., with transmission housing 68. A torque transfer device, i.e.
C4 75 is operative as a lock-up clutch, locking planetary gear sets 24, 26, MG-
A and MG-B 56, 72 and the input to rotate as a group, by selectively
connecting the sun gear 40 with the carrier 44. The torque transfer devices 62,
70, 73, 75 are all friction clutches, respectively referred to as follows: clutch
Cl 70, clutch C2 62, clutch C3 73, and clutch C4 75. Each clutch is
preferably hydraulically actuated, receiving pressurized hydraulic fluid from a
pump when a corresponding clutch control solenoid is actuated. Hydraulic
actuation of each of the clutches is accomplished using a known hydraulic
fluid circuit having a plurality of clutch-control solenoids, which is not
described in detail herein.
[0034] The transmission 10 receives input motive torque from the torque-
generative devices, including the engine 14 and the electrical machines 56
and 72, as a result of energy conversion from fuel or electrical potential
stored in an electrical energy storage device (ESD) 74. The ESD 74
typically comprises one or more batteries. Other electrical energy and
electrochemical energy storage devices that have the ability to store electric
power and dispense electric power may be used in place of the batteries
without altering the concepts of the present invention. The ESD 74 is
preferably sized based upon factors including regenerative requirements,
application issues related to typical road grade and temperature, and
propulsion requirements such as emissions, power assist and electric range.
The ESD 74 is high voltage DC-coupled to transmission power inverter

9
module (TPIM) 19 via DC lines or transfer conductors 27. The TPIM 19 is
an element of the control system described hereinafter with regard to Fig. 2.
The TPIM 19 communicates with the first electrical machine 56 by transfer
conductors 29, and the TPIM 19 similarly communicates with the second
electrical machine 72 by transfer conductors 31. Electrical current is
transferable to or from the ESD 74 in accordance with whether the ESD 74
is being charged or discharged. TPIM 19 includes the pair of power
inverters and respective motor controllers configured to receive motor
control commands and control inverter states therefrom for providing motor
drive or regeneration functionality.
[0035] In motoring control, the respective inverter receives current from
the DC lines and provides AC current to the respective electrical machine,
i.e. MG-A and MG-B, over transfer conductors 29 and 31. In regeneration
control, the respective inverter receives AC current from the electrical
machine over transfer conductors 29 and 31 and provides current to the DC
lines 27. The net DC current provided to or from the inverters determines
the charge or discharge operating mode of the electrical energy storage
device 74. Preferably, MG-A 56 and MG-B 72 are three-phase AC
machines and the inverters comprise complementary three-phase power
electronics.
[0036] Referring again to Fig. 1, a drive gear 80 may be presented from the
input member 12. As depicted, the drive gear 80 fixedly connects the input
member 12 to the outer gear member 30 of the first planetary gear set 24, and
the drive gear 80, therefore, receives power from the engine 14 and/or the
electrical machines 56 and/or 72 through planetary gear sets 24 and/or 26. The
drive gear 80 meshingly engages an idler gear 82 which, in turn, meshingly
engages a transfer gear 84 that is secured to one end of a shaft 86. The other
end of the shaft 86 may be secured to a hydraulic/transmission fluid pump
and/or power take-off ('PTO') unit, designated either individually or
collectively at 88, and comprise an accessory load.

10
[0037] Referring now to Fig. 2, a schematic block diagram of the control
system, comprising a distributed controller architecture, is shown. The
elements described hereinafter comprise a subset of an overall vehicle control
architecture, and are operable to provide coordinated system control of the
powertrain system described herein. The control system is operable to
synthesize pertinent information and inputs, and execute algorithms to control
various actuators to achieve control targets, including such parameters as fuel
economy, emissions, performance, driveability, and protection of hardware,
including batteries of ESD 74 and MG-A and MG-B 56, 72. The distributed
controller architecture includes engine control module ('ECM') 23,
transmission control module ('TCM') 17, battery pack control module
('BPCM') 21, and Transmission Power Inverter Module ('TPIM') 19. A
hybrid control module ('HCP') 5 provides overarching control and
coordination of the aforementioned controllers. There is a User Interface
('UI') 13 operably connected to a plurality of devices through which a vehicle
operator typically controls or directs operation of the powertrain, including the
transmission 10. Exemplary vehicle operator inputs to the UI 13 include an
accelerator pedal, a brake pedal, transmission gear selector, and, vehicle speed
cruise control. Each of the aforementioned controllers communicates with
other controllers, sensors, and actuators via a local area network ('LAN') bus
6. The LAN bus 6 allows for structured communication of control parameters
and commands between the various controllers. The specific communication
protocol utilized is application-specific. By way of example, one
communications protocol is the Society of Automotive Engineers standard
J1939. The LAN bus and appropriate protocols provide for robust messaging
and multi-controller interfacing between the aforementioned controllers, and
other controllers providing functionality such as antilock brakes, traction
control, and vehicle stability.
[0038] The HCP 5 provides overarching control of the hybrid powertrain
system, serving to coordinate operation of the ECM 23, TCM 17, TPIM 19,
and BPCM 21. Based upon various input signals from the UI 13 and the

11
powertrain, including the battery pack, the HCP 5 generates various
commands, including: an engine torque command, clutch torque commands,
TCL_N for the various clutches Cl, C2, C3, C4 of the transmission 10; and
motor torque commands, TAand TB, for MG-A and MG-B, respectively.
[0039] The ECM 23 is operably connected to the engine 14, and functions to
acquire data from a variety of sensors and control a variety of actuators,
respectively, of the engine 14 over a plurality of discrete lines collectively
shown as aggregate line 35. The ECM 23 receives the engine torque
command, TECMD, from the HCP 5, and generates a desired axle torque, and
an indication of actual engine torque, Tl input to the transmission, which is
communicated to the HCP 5. For simplicity, ECM 23 is shown generally
having bi-directional interface with engine 14 via aggregate line 35. Various
other parameters that may be sensed by ECM 23 include engine coolant
temperature, engine input speed (Ni) to shaft 12 leading to the transmission,
manifold pressure, ambient air temperature, and ambient pressure. Various
actuators that may be controlled by the ECM 23 include fuel injectors, ignition
modules, and throttle control modules.
[0040] The TCM 17 is operably connected to the transmission 10 and
functions to acquire data from a variety of sensors and provide command
signals to the transmission. Inputs from the TCM 17 to the HCP 5 include
estimated clutch torques, TCL_N_EST, for each of the clutches Cl, C2, C3, and,
C4 and rotational speed, No, of the output shaft 64. Other actuators and
sensors may be used to provide additional information from the TCM to the
HCP for control purposes.
[0041] The BPCM 21 is signally connected one or more sensors operable to
monitor electrical current or voltage parameters of the ESD 74 to provide
information about the state of the batteries to the HCP 5. Such information
includes battery state-of-charge, battery voltage, VBAT, and available battery
power, PBAT_MIN and PBAT_MAX.
[0042] The Transmission Power Inverter Module (TPIM) 19 includes a
pair of power inverters and motor controllers configured to receive motor

12
control commands and control inverter states therefrom to provide motor
drive or regeneration functionality. The TPIM 19 is operable to generate
torque commands for MG-A 56 and MG-B 72, TA and TB, based upon input
from the HCP 5, which is driven by operator input through Ul 13 and
system operating parameters. The motor torque commands for MG-A and
MG-B, i.e. TA and TB, are implemented by the control system, including the
TPIM 19, to control MG-A and MG-B. Individual motor speed signals, NA
and NB for MG-A and MG-B respectively, are derived by the TPIM 19 from
the motor phase information or conventional rotation sensors. The TPIM 19
determines and communicates motor speeds, NAand NB, to the HCP 5. The
electrical energy storage device 74 is high-voltage DC-coupled to the TPIM
19 via DC lines 27. Electrical current is transferable to or from the TPIM
19 in accordance with whether the ESD 74 is being charged or discharged.
[0043] Each of the aforementioned controllers is preferably a general-
purpose digital computer generally comprising a microprocessor or central
processing unit, storage mediums comprising read only memory (ROM),
random access memory (RAM), electrically programmable read only memory
(EPROM), high speed clock, analog to digital (A/D) and digital to analog
(D/A) circuitry, and input/output circuitry and devices (I/O) and appropriate
signal conditioning and buffer circuitry. Each controller has a set of control
algorithms, comprising resident program instructions and calibrations stored in
ROM and executed to provide the respective functions of each computer.
Information transfer between the various computers is preferably
accomplished using the aforementioned LAN 6.
[0044] Algorithms for control and state estimation in each of the controllers
are typically executed during preset loop cycles such that each algorithm is
executed at least once each loop cycle. Algorithms stored in the non-volatile
memory devices are executed by one of the central processing units and are
operable to monitor inputs from the sensing devices and execute control and
diagnostic routines to control operation of the respective device, using preset
calibrations. Loop cycles are typically executed at regular intervals, for

13
example each 3.125, 6.25, 12.5, 25 and 100 milliseconds during ongoing
engine and vehicle operation. Alternatively, algorithms may be executed in
response to occurrence of an event.
[0045] In response to an operator's action, as captured by the UI 13, the
supervisory HCP controller 5 and one or more of the other controllers
determine required transmission output torque, To at shaft 64. Selectively
operated components of the transmission 10 are appropriately controlled and
manipulated to respond to the operator demand. For example, in the
exemplary embodiment shown in Fig. 1 and 2, when the operator has selected
a forward drive range and manipulates either the accelerator pedal or the brake
pedal, the HCP 5 determines an output torque for the transmission, To, which
affects how and when the vehicle accelerates or decelerates. Final vehicle
acceleration is affected by other factors, including, e.g., road load, road grade,
and vehicle mass. The HCP 5 monitors the parametric states of the torque-
generative devices, and determines the output of the transmission required to
arrive at the desired torque output. Under the direction of the HCP 5, the
transmission 10 operates over a range of output speeds from slow to fast in
order to meet the operator demand.
[0046] The two-mode, compound-split, electro-mechanical transmission,
includes output member 64 which receives output power through two distinct
gear trains within the transmission 10, and operates in several transmission
operating modes, described with reference now to Fig. 1, and Table 1, below.
Table 1
Transmission Operating Mode Actuated Clutches
Mode l Cl 70
Fixed Ratio (GR1) Cl 70 C4 75
Fixed Ratio (GR2) Cl 70 C2 62
Mode II C2 62
Fixed Ratio (GR3) C2 62 C4 75
Fixed Ratio (GR4) C2 62 C3 73

14
[0047] The various transmission operating modes described in the table
indicate which of the specific clutches Cl, C2, C3, C4 are engaged or actuated
for each of the operating modes. Additionally, in various transmission
operating modes, MG-A and MG-B may each operate as electrical motors to
generate motive torque, or as a generator to generate electrical energy. A first
mode, or gear train, is selected when the torque transfer device 70 is actuated
in order to "ground" the outer gear member 46 of the third planetary gear set
28. A second mode, or gear train, is selected when the torque transfer device
70 is released and the torque transfer device 62 is simultaneously actuated to
connect the shaft 60 to the carrier 52 of the third planetary gear set 28. Other
factors outside the scope of the invention affect when MG-A and MG-B 56, 72
operate as motors and generators, and are not discussed herein.
[0048] The control system, shown primarily in Fig. 2, is operable to provide
a range of transmission output speeds, No, of shaft 64 from relatively slow to
relatively fast within each mode of operation. The combination of two modes
with a slow-to-fast output speed range in each mode allows the transmission
10 to propel a vehicle from a stationary condition to highway speeds, and meet
various other requirements as previously described. Additionally, the control
system coordinates operation of the transmission 10 so as to allow
synchronized shifts between the modes.
[0049] The first and second modes of operation refer to circumstances in
which the transmission functions are controlled by one clutch, i.e. either clutch
Cl 62 or C2 70, and by the controlled speed and torque of machines MG-A
and MG-B 56 and 72, which can be referred to as a continuously variable
transmission mode. Certain ranges of operation are described below in which
fixed ratios are achieved by applying an additional clutch. This additional
clutch may be clutch C3 73 or C4 75, as shown in the table, above.
[0050] When the additional clutch is applied, fixed ratio of input-to-output
speed of the transmission, i.e. NI/N0, is achieved. The rotations of machines
MG-A and MG-B 56, 72 are dependent on internal rotation of the mechanism
as defined by the clutching and proportional to the input speed, NI determined

15
or measured at shaft 12. The machines MG-A and MG-B operate as motors or
generators. They are completely independent of engine to output power flow,
thereby enabling both to be motors, both to function as generators, or any
combination thereof. This allows, for instance, during operation in Fixed Ratio
1 that motive power output from the transmission at shaft 64 is provided by
power from the engine and power from MG-A and MG-B, through planetary
gear set 28 by accepting power from the energy storage device 74.
[0051] The transmission operating mode can be switched between Fixed
Ratio operation and continuously variable Mode operation by activating or
deactivating one the additional clutches during Mode I or Mode II operation.
Determination of operation in fixed ratio mode or continuously variable mode
is by algorithms executed by the control system, and is outside the scope of
this invention.
[0052] The modes of operation may overlap the ratio of operation, and
selection depends again on the driver's input and response of the vehicle to
that input. RANGE 1 falls primarily within mode I operation when clutches
Cl 70 and C4 75 are engaged. RANGE 2 falls within mode I and mode II
when clutches C2 62 and Cl 70 are engaged. A third fixed ratio range is
available primarily during mode II when clutches C2 62 and C4 75 are
engaged, and a fourth fixed ratio range is available during mode II when
clutches C2 62 and C3 73 are engaged. It is notable that ranges of operation
for Mode I and Mode II typically overlap significantly.
[0053] Output of the exemplary powertrain system described hereinabove is
constrained due to mechanical and system limitations. The output speed, No,
of the transmission measured at shaft 64 is limited due to limitations of engine
output speed, NE, measured at shaft 18, and transmission input speed, Nl
measured at shaft 12, and speed limitations of the MG-A and MG-B,
designated as +/- NA, +/- NB. Output torque, To, of the transmission 64 is
similarly limited due to limitations of the engine input torque, TE, and input
torque, Tl, measured at shaft 12 after the transient torque damper 20, and

16
torque limitations (TA_MAx, TA_MIN, TB_MAX, TB_MIN) of MG-A and MG-B 56,
72.
[0054] In operation, a shift occurs in the exemplary transmission due to a
change in operator demand for output torque, typically communicated through
inputs to the UI 13, including the accelerator pedal, the brake pedal, the
transmission gear selector, and, the vehicle speed cruise control system.
Additionally, a change in demand for output torque may be predicated on a
change in external conditions, including, e.g. changes in road grade, road
surface conditions, or wind load. Furthermore, a change in demand for output
torque may be predicated on a change in powertrain torque demand caused by
a controller command to change one of the electrical machines between
electrical energy generating mode and torque generating mode. The
distributed control architecture acts in concert to determine a need for a
change in transmission operating gear, and executes the forgoing to effect the
change in gear.
[0055] Referring now to Fig. 3, a graphical depiction of an element of a
fixed gear-to-fixed gear shifting event is now described, comprising
controlling operation of various machines and actuators of the aforementioned
powertrain system. Referring specifically to Fig. 3A, graphs of input speed,
N1, as a function of time, are shown for operation of the exemplary powertrain
system. Line A comprises a depiction of input speed, N1, showing a
relationship with transmission output, No, multiplied by the first gear ratio,
GR1, previously described with reference to Table 1. Line B comprises a
depiction of input speed, NI; showing a relationship with transmission output,
No, multiplied by the second gear ratio, GR2, also previously described with
reference to Table 1. Line C comprises a depiction of input speed, N1 during a
shift event, wherein there is a controlled transition from operation in. the first
gear ratio GR1 to operation in the second gear ratio GR2, beginning at time
point 110 and ending at time point 120.
[0056] Referring specifically to Fig. 3B, a profile of a change in input speed,
N1_dot during the shift transition operation is shown, wherein there are three

17
distinct regions of operation of changes in the input speed,N1_dot. The three
regions of operation preferably comprise: Region D, wherein N,_dot is
decreasing, indicating a deceleration of the engine input to the transmission;
Region E, wherein Nldot is a constant value; and, Region F, wherein N1_dot
is increasing, indicating an acceleration of the engine input to the
transmission. The profile for N1dot is preferably a predetermined profile
which is stored in the control system and executed to control operation of the
engine during the shift event.
[0057] Referring specifically to Fig. 3C, a plurality of torque output graphs
are depicted during the shift from the first fixed gear (shown herein for GR1)
to the second fixed gear (shown herein for GR2). Line G comprises a torque
profile comprising an idealized linear time-based interpolation of output
torque between GR1 and GR2, wherein there is no consideration for system
momentums and inertias, and restraints on outputs of the torque-generative
devices. Line H comprises a torque profile for output torque based upon
maximum torque-generating capabilities of the electric machines, MG-A 56
and MG-B 72, as further restrained by the output of the battery pack or ESD
74. Line H does not include torque generation by an oncoming clutch, in this
case clutch C2. Line I comprises a calibrated time-based value of output
torque To, which is derived based upon operator expectations for torque output
to vehicle driveline during a shifting event. Line I is a predetermined profile
for torque output from the transmission, preferably to shaft 64, stored in one of
the control modules of the control system. The torque output is necessarily
limited based upon torque-generative capacity of the system, including
operating limits of the oncoming clutch, in this case C2.
[0058] The operating limits of the oncoming clutch are driven primarily by a
limit on clutch energy. Clutch energy is driven by an increase in clutch
temperature caused by clutch slippage, as is described hereinafter. Line J
comprises a maximum executed torque output for operating the transmission,
preferably derived based upon all of the aforementioned constraints, Including
the profile of change in input speed, N1_dot, the idealized linear time-based

18
interpolation of the output torque, To, between GR1 and GR2, the output
torque based upon maximum torque-generating capabilities of the electric
machines, the calibrated time-based value of the output torque To, which is
derived based upon operator expectations for torque output, and the operating
limits of the oncoming clutch. This operation is described herein.
[0059] The relationships described with regard to Fig. 3 can be described
mathematically, which can then be reduced to algorithms executable in the
control system described above. A governing equation is shown below, in Eq.
1:
[0060] wherein:
[0061] T1 and To are input and output torques of the transmission,
respectively;
[0062] TA and TB are output torques of MG-A and MG-B, respectively;
[0063] Tc_ON is torque of the oncoming clutch, e.g. C2 for G2 in this
example; and
[0064] C11, C12, C21, C22, D11, D12, D21, D22, KI, and Ko comprise
experimentally derived scalar values.
[0065] Eq. 1 is reduceable to:

[0066]

[0067] wherein:
[0068] T1M, T0M represent the input and output motor torques,
[0069] T,N, T0N represent input and output transmission torques; and,
[0070] T1C and T0C represent the oncoming clutch torques.
[0071] Eq. 2 is reduceable to:
[0073] An important practical significance of the values for Eq. 3 includes
that a maximum value for the ToX factor is represented by Line H of Fig. 3C.




19
[0074] Referring again to Fig. 3 and Eqs. 1, 2, and 3, the value for N^dot is
a known calibration, and No_dot is a readily measurable value, measured at
output shaft 64. Values for TA and TB are known, measured values by
measuring current through the TPIM to each of MG-A and MG-B. Therefore,
a range of needed values for oncoming clutch torque, TC_ON is determinable
and calculable.
[0075] Once the range of needed values for oncoming clutch torque, Tc_0N is
determined, the limitations based upon clutch torque energy can be derived,
resulting in the desired output torque shown with reference again to Line I of
Fig. 3C. The operating limits of the oncoming clutch, in this case C2 are
determined as follows, driven primarily by a limit on clutch energy, due to an
increase in clutch temperature caused by clutch slippage. This determination
of allowable energy is now described by way of example. The exemplary
clutch, C2, has a maximum allowable operating temperature range from 80 C
to 250 C, over an associated thermal capacity of 20 kilojoules (kJ). Clutch
temperature can be estimated based upon operating temperature of the
transmission and other factors. It is estimated, for sake of calculation, as 150
C in this instance, which means the remaining clutch energy is 20 * (100/170)
or about 12 kJ. It is assumed that a shift event requires an elapsed time of one
half second, or 500 milliseconds. During the elapsed time in which the shift
event occurs, clutch slippage is determined based upon the N1dot profile, and
the output speed and oncoming gear ratio, N0*GR2. Using known
relationships between power, energy, and time, it can be readily determined
that clutch energy, in the form of slippage and clutch friction, must not exceed
a maximum value of 160 N-m in this example in order to maintain physical
integrity of the clutch device. The oncoming clutch torque, Tc-on, can be
determined based thereupon.
[0076] It is understood that application-specific masses, inertias, friction
factors, and other characteristics and parameters of the driveline affect various
powertrain and driveline operating states, and therefore the response times and

20
magnitudes are intended to be exemplary, while still descriptive of the overall
operation of the powertrain system.
[0077] As previously described, the transmission device 10 comprises a
plurality of gears and torque-transfer devices operable to transmit torque
between the torque-generative devices 14, 56, 72 and the output shaft 64 and
drive wheels 96 of the driveline. Torque transmission may comprise transfer
of motive torque from one or more of the torque-generative devices 14, 56, 72
to the driveline. Torque transmission may comprise transfer of torque from
the drive wheels 96 via the driveline and transmission to one or more of the
torque-generative devices 14, 56, 72 as a result of a process commonly
referred to as engine-braking. In this configuration, engine-braking comprises
transmitting at least a portion of driveline torque resulting from vehicle
momentum from the output shaft 64 through torque-transfer devices, i.e.,
clutches Cl, C2, C3, C4, to the torque-generative devices 14, 56, 72. The
transmitted torque is absorbed by the powertrain in the form of electrical
energy generation through MG-A and MG-B, and, engine braking through the
internal combustion engine 14.
[0078] It is understood that modifications in the transmission hardware are
allowable within the scope of the invention. The invention has been described
with specific reference to the preferred embodiments and modifications
thereto. Further modifications and alterations may occur to others upon
reading and understanding the specification. It is intended to include all such
modifications and alterations insofar as they come within the scope of the
invention.

21
Having thus described the invention, it is claimed:
1. Article of manufacture, comprising a storage medium having a
computer program encoded therein for effecting a method to control torque
output from a transmission device during a gear-to-gear shifting event when
an off-going torque-transfer device is disengaged, the program comprising:
5 code comprising a predetermined preferred torque output from the
transmission device;
code to control torque output from each of a plurality of torque-generative
devices operative to transmit motive torque to the transmission device;
and,
10 code to control torque transmitted across a selectively actuated torque transfer
device.
2. The article of manufacture of claim 1, wherein the code to control
torque transmitted across a selectively actuated torque transfer device further
comprises code to control torque output from each of the torque-generative
devices to substantially match the predetermined preferred torque output from
5 the transmission device.
3. The article of manufacture of claim 2, wherein the transmission
comprises a two-mode, compound-split, electro-mechanical transmission.
4. The article of manufacture of claim 3, wherein the torque-generative
devices comprise electrical machines.
5. The article of manufacture of claim 4, further comprising the plurality
of torque-generative devices operative to transmit motive torque to the
transmission device wherein the motive torque is limited based upon battery
power.

22
6. The article of manufacture of claim 5, wherein the electrical machines
are each operable to independently transmit motive torque to the transmission
device.
7. The article of manufacture of claim 6, wherein the torque-generative
devices further comprise an internal combustion engine.
8. The article of manufacture of claim 3, wherein the two-mode,
compound-split, electro-mechanical transmission comprises a transmission
including four torque-transfer devices operative to control the transmission in
operating ranges comprising four fixed-gear modes and two continuously
5 variable modes.
9. The article of manufacture of claim 8, wherein the powertrain system
is operable to provide motive torque to a driveline of a vehicle.
10. The article of manufacture of claim 1, wherein the code comprising a
predetermined preferred torque output from the transmission device comprises
a series of time-based values for output torque derived based upon operator
expectations during a shifting event.
11. The article of manufacture of claim 1, wherein the code to control
torque transmitted across the selectively actuated torque transfer device further
comprises code to control actuation of the torque-transfer device based upon a
temperature of the selectively actuated torque-transfer device during the
5 shifting event.
12. The article of manufacture of claim 11, wherein the temperature of the
selectively actuated torque-transfer device during the shifting event is
determined based upon a rotational speed of an input shaft to the transmission
and an elapsed time to execute the shift event.

23
13. The article of manufacture of claim 1, wherein the code to control
torque transmitted across the selectively actuated torque transfer device further
comprises code to control actuation of the torque-transfer device based upon
slippage of the selectively actuated torque-transfer device during the shifting
5 event.
14. Control system, for a powertrain comprising a plurality of torque-
generative devices operatively connected to a power transmission device
operable in a plurality of fixed gear ratios each fixed gear ratio effected by
selective actuation of a plurality of torque-transfer devices, the control system
5 operable to execute a computer program to effect a method to control torque
output from the power transmission device during a gear-to-gear shifting event
when an off-going torque-transfer device is disengaged, the computer program
comprising:
code comprising a predetermined preferred torque output from the
10 transmission device;
code to control torque output from each of the torque-generative devices
operative to transmit motive torque to the transmission device; and,
code to control torque transmitted across a selectively actuated torque transfer
device to optimize an operating temperature of the selectively actuated
15 torque-transfer device.
15. The control system of claim 14, further comprising code to control
torque output from each of the torque-generative devices operative to transmit
motive torque to the transmission device during the shifting event.
16. The control system of claim 15, further comprising the control system
operable to control torque output from each of the torque-generative devices
and the selectively actuated torque-transfer device to substantially match the
predetermined preferred torque output from the transmission device.

24
17. The control system of claim 16, wherein the torque-generative devices
comprise an internal combustion engine, a first electrical machine, and a
second electrical machine.
18. The control system of claim 14, wherein the magnitude of torque
transmitted from the first and second electrical machines is determined based
upon available electrical power transmittable from an electrical energy storage
device.
19. Method for controlling torque output from a transmission device
during a gear-to-gear shifting event when an off-going torque-transfer device
is disengaged, comprising:
predetermining a preferred torque output from the transmission device;
5 controlling torque output from each of a plurality of torque-generative devices
operative to transmit motive torque to the transmission device; and,
controlling torque transmitted across a selectively actuated torque transfer
device.
20. The method of claim 19, wherein controlling torque output from each
of the plurality of torque-generative devices operative to transmit motive
torque to the transmission device further comprises limiting torque output
from each of the torque-generative devices based upon available battery power
5 when the torque-generative devices comprise electrical machines.
21. The method of claim 20, wherein controlling torque transmitted across
the selectively actuated torque transfer device further comprises controlling
actuation of the torque transfer device based upon a temperature of the torque
transfer device during the shift event.

25
22. The method of claim 21, further comprising determining the
temperature of the torque transfer device during the shift event based upon
rotation of an input shaft to the transmission and an elapsed time to shift.

A control system is provided to effect a method to control torque output from a two-mode, compound-split, electro-mechanical transmission during gear-to-gear shifting event when an off-going torque-transfer device is disengaged. It includes a computer program which controls transmission operation. A predetermined preferred torque output from the transmission device is determined. Torque output from torque-generative devices device is controlled. Torque transmitted across a selectively actuated torque transfer device is controlled, and limited based upon available battery power. Actuation of the oncoming torque-transfer device is preferably based upon a temperature of the device during the shifting event. The temperature during the shifting event is determined based upon a rotational speed of an input shaft to the transmission and an elapsed time to shift.

Documents:

00684-kol-2007-abstract.pdf

00684-kol-2007-assignment.pdf

00684-kol-2007-claims.pdf

00684-kol-2007-correspondence others 1.1.pdf

00684-kol-2007-correspondence others 1.2.pdf

00684-kol-2007-correspondence others 1.3.pdf

00684-kol-2007-correspondence others 1.4.pdf

00684-kol-2007-correspondence others.pdf

00684-kol-2007-description complete.pdf

00684-kol-2007-drawings.pdf

00684-kol-2007-form 1.pdf

00684-kol-2007-form 18.pdf

00684-kol-2007-form 2.pdf

00684-kol-2007-form 3.pdf

00684-kol-2007-form 5.pdf

00684-kol-2007-gpa.pdf

00684-kol-2007-priority document.pdf

684-KOL-2007-ABSTRACT.pdf

684-KOL-2007-AMANDED CLAIMS.pdf

684-KOL-2007-ASSIGNMENT.pdf

684-KOL-2007-CORRESPONDENCE 1.6.pdf

684-KOL-2007-CORRESPONDENCE.1.5.pdf

684-KOL-2007-DESCRIPTION (COMPLETE).pdf

684-KOL-2007-DRAWINGS.pdf

684-KOL-2007-EXAMINATION REPORT REPLY RECIEVED.pdf

684-KOL-2007-EXAMINATION REPORT.pdf

684-KOL-2007-FORM 1.pdf

684-KOL-2007-FORM 18.pdf

684-KOL-2007-FORM 2.pdf

684-KOL-2007-FORM 26.pdf

684-KOL-2007-FORM 3 1.1.pdf

684-KOL-2007-FORM 3.pdf

684-KOL-2007-FORM 5.pdf

684-KOL-2007-GRANTED-ABSTRACT.pdf

684-KOL-2007-GRANTED-CLAIMS.pdf

684-KOL-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

684-KOL-2007-GRANTED-DRAWINGS.pdf

684-KOL-2007-GRANTED-FORM 1.pdf

684-KOL-2007-GRANTED-FORM 2.pdf

684-KOL-2007-GRANTED-LETTER PATENT.pdf

684-KOL-2007-GRANTED-SPECIFICATION.pdf

684-KOL-2007-OTHERS 1.1.pdf

684-KOL-2007-OTHERS.pdf

684-KOL-2007-PA.pdf

684-KOL-2007-PETITION UNDER RULE 137.pdf

684-KOL-2007-REPLY TO EXAMINATION REPORT.pdf

684-KOL-2007-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf


Patent Number 253209
Indian Patent Application Number 684/KOL/2007
PG Journal Number 27/2012
Publication Date 06-Jul-2012
Grant Date 04-Jul-2012
Date of Filing 04-May-2007
Name of Patentee GM GLOBAL TECHNOLOGY OPERATIONS, INC.
Applicant Address 300 GM RENAISSANCE CENTER DETROIT, MICHIGAN
Inventors:
# Inventor's Name Inventor's Address
1 JY-JEN F. SAH 1915 BLOOMFIELD OAKS DRIVE WEST BLOOMFIELD, MICHIGAN 48324
PCT International Classification Number F16H61/02;B60W10/06,
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 11/428,030 2006-06-30 U.S.A.