U.S. patent application number 12/145990 was filed with the patent office on 2009-12-31 for hybrid automotive powertrain system and method of operating same.
This patent application is currently assigned to FORD GLOBAL TECHNOLOGIES, LLC. Invention is credited to William Paul Perkins.
Application Number | 20090321156 12/145990 |
Document ID | / |
Family ID | 41446053 |
Filed Date | 2009-12-31 |
United States Patent
Application |
20090321156 |
Kind Code |
A1 |
Perkins; William Paul |
December 31, 2009 |
HYBRID AUTOMOTIVE POWERTRAIN SYSTEM AND METHOD OF OPERATING
SAME
Abstract
A hybrid powertrain system for a vehicle includes an electric
machine, a gear set mechanically connected with the electric
machine, and a clutch mechanically coupled with at least one of a
primary and secondary driveline assembly. The electric machine is
configured to selectively provide motive power to at least one of
the primary and secondary driveline assemblies. The gear set is
configured to permit differential rotation between the primary and
secondary driveline assemblies. The clutch is configured to
selectively transfer torque between the primary and secondary
driveline assemblies.
Inventors: |
Perkins; William Paul;
(Dearborn, MI) |
Correspondence
Address: |
BROOKS KUSHMAN P.C./FGTL
1000 TOWN CENTER, 22ND FLOOR
SOUTHFIELD
MI
48075-1238
US
|
Assignee: |
FORD GLOBAL TECHNOLOGIES,
LLC
Dearborn
MI
|
Family ID: |
41446053 |
Appl. No.: |
12/145990 |
Filed: |
June 25, 2008 |
Current U.S.
Class: |
180/65.7 ;
192/54.1; 475/5; 903/906; 903/907; 903/910 |
Current CPC
Class: |
B60K 6/48 20130101; B60K
1/00 20130101; B60K 2006/4833 20130101; B60K 6/52 20130101; B60K
17/356 20130101; B60K 1/04 20130101; B60K 6/26 20130101; Y02T 10/62
20130101 |
Class at
Publication: |
180/65.7 ; 475/5;
192/54.1; 903/910; 903/906; 903/907 |
International
Class: |
B60K 6/26 20071001
B60K006/26; B60K 6/28 20071001 B60K006/28; B60K 6/365 20071001
B60K006/365 |
Claims
1. A hybrid powertrain system for a vehicle comprising: a clutch
mechanically coupled with at least one of a primary driveline
assembly and secondary driveline assembly and configured to
selectively transfer torque therebetween; an electric machine
configured to selectively provide motive power to at least one of
the primary driveline assembly and secondary driveline assembly;
and a gear set mechanically connected with the electric machine and
configured to permit differential rotation between the primary
driveline assembly and secondary driveline assembly.
2. The system of claim 1 wherein the electric machine is further
configured to selectively convert motive power received from at
least one of the primary driveline assembly and secondary driveline
assembly to electrical power.
3. The system of claim 1 wherein the electric machine is further
configured to selectively free spin.
4. The system of claim 1 wherein the gear set includes a first
element mechanically connected with the electric machine.
5. The system of claim 4 wherein the gear set further includes a
second element mechanically connected with one of the primary
driveline assembly and secondary driveline assembly.
6. The system of claim 5 wherein the gear set comprises an
epicyclic gear set and wherein the epicyclic gear set further
includes a third element mechanically connected with the other of
the primary driveline assembly and secondary driveline
assembly.
7. The system of claim 1 wherein the clutch is further configured
to vary the torque transfer between the primary driveline assembly
and secondary driveline assembly.
8. The system of claim 1 wherein the vehicle further includes an
energy storage unit and wherein the electric machine is further
configured to provide electrical power to the energy storage
unit.
9. The system of claim 1 wherein the vehicle further includes an
energy storage unit and wherein the electric machine is further
configured to receive electrical power from the energy storage
unit.
10. An automotive hybrid powertrain system for a vehicle including
a primary driveline assembly and secondary driveline assembly, the
system comprising: a power transfer box including an electric
machine, a gear set mechanically connected with the electric
machine, and a clutch mechanically coupled with at least one of the
primary driveline assembly and secondary driveline assembly, the
power transfer box being configured to selectively (i) provide
motive power to at least one of the primary driveline assembly and
secondary driveline assembly by converting electrical power to
motive power, (ii) convert motive power received from at least one
of the primary driveline assembly and secondary driveline assembly
to electrical power, (iii) transfer torque between the secondary
driveline assembly and primary driveline assembly via the clutch,
(iv) transfer torque between the secondary driveline assembly and
primary driveline assembly via the gear set, and (v) transfer
torque between the electric machine and at least one of the primary
driveline assembly and secondary driveline assembly via the gear
set.
11. The system of claim 10 wherein the power transfer box is
further configured to permit differential rotation between the
secondary driveline assembly and primary driveline assembly.
12. The system of claim 10 wherein the gear set includes a first
element mechanically connected with the electric machine.
13. The system of claim 12 wherein the gear set includes a second
element mechanically connected with one of the primary driveline
assembly and secondary driveline assembly.
14. The system of claim 13 wherein the gear set comprises an
epicyclic gear set and wherein the epicyclic gear set includes a
third element mechanically connected with the other of the primary
driveline assembly and secondary driveline assembly.
15. The system of claim 10 wherein the vehicle further includes an
energy storage unit and wherein the electric machine is further
configured to provide electrical power to the energy storage
unit.
16. The system of claim 10 wherein the vehicle further includes an
energy storage unit and wherein the electric machine is further
configured to receive electrical power from the energy storage
unit.
17. A method for operating a power transfer box of an automotive
hybrid powertrain, the method comprising: providing motive power to
at least one of a primary driveline assembly and secondary
driveline assembly by converting electrical power to motive power;
transferring torque between the secondary driveline assembly and
primary driveline assembly via a clutch; and transferring torque
between the secondary driveline assembly and primary driveline
assembly via a gear set.
18. The method of claim 17 further comprising converting motive
power received from at least one of the primary driveline assembly
and secondary driveline assembly to electrical power.
19. The method of claim 17 further comprising transferring torque
between an electric machine and at least one of the primary
driveline assembly and secondary driveline assembly via the gear
set.
20. The method of claim 17 further comprising permitting
differential rotation between the secondary driveline assembly and
primary driveline assembly.
21. The method of claim 17 further comprising providing electrical
power to an energy storage unit.
22. The method of claim 17 further comprising receiving electrical
power from an energy storage unit.
23. An automotive hybrid powertrain system comprising: an electric
machine configured to selectively provide motive power to at least
one of a primary driveline assembly and secondary driveline
assembly by converting electrical power to motive power; an
epicyclic gear set including a sun gear mechanically connected with
the electric machine, at least one planet gear mechanically coupled
with one of the primary driveline assembly and secondary driveline
assembly and a non-rotating ring gear; and a clutch mechanically
coupled with at least one of the primary driveline assembly and
secondary driveline assembly and configured to selectively transfer
torque between the primary driveline assembly and secondary
driveline assembly.
24. The system of claim 23 wherein the electric machine is further
configured to selectively convert motive power received from at
least one of the primary driveline assembly and secondary driveline
assembly to electrical power.
25. The system of claim 23 wherein the electric machine is further
configured to selectively free spin.
26. The system of claim 23 wherein the clutch is further configured
to vary the torque transfer between the primary driveline assembly
and secondary driveline assembly.
27. The system of claim 23 wherein the electric machine is further
configured to provide electrical power to an energy storage
unit.
28. The system of claim 23 wherein the electric machine is further
configured to receive electrical power from an energy storage
unit.
29. A hybrid powertrain system for a vehicle including a primary
driveline assembly and secondary driveline assembly, the system
comprising: a power transfer box including an electric machine, a
clutch mechanically coupled with at least one of the primary
driveline assembly and secondary driveline assembly, and a gear set
including a first element mechanically connected with the electric
machine and a second element mechanically coupled with one of the
primary driveline assembly and secondary driveline assembly, the
power transfer box being configured to selectively (i) provide
motive power to at least one of the primary driveline assembly and
secondary driveline assembly by converting electrical power to
motive power via the electric machine, and (ii) transfer torque
between the secondary driveline assembly and primary driveline
assembly via the clutch.
30. The system of claim 29 wherein the power transfer box is
further configured to selectively transfer torque between the
electric machine and at least one of the primary driveline assembly
and secondary driveline assembly.
31. The system of claim 29 wherein the power transfer box is
further configured to convert motive power received from at least
one of the primary driveline assembly and secondary driveline
assembly to electrical power via the electric machine.
32. The system of claim 29 wherein the gear set comprises an
epicyclic gear set and wherein the epicyclic gear set includes a
non-rotating third element.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The invention relates to hybrid automotive powertrain
systems and methods of operating the same.
[0003] 2. Discussion
[0004] Drivetrains for hybrid automotive vehicles may be configured
and operated in several ways. As an example, U.S. Pat. No.
5,993,351 to Deguchi et al. discloses a first electrical motor
mechanically connected to an engine and a second electrical motor
mechanically connected to the engine through a clutch. Motive force
is transmitted from the second electrical motor to drive wheels
through a transmission. It is decided whether to release the clutch
based on a detected vehicle speed and a detected required motive
force. Engine output at that time is estimated. The second
electrical motor is controlled such that generated torque
corresponds to the estimated engine output if it is decided to
release the clutch. The first electrical motor is controlled such
that the torque generated by the second electrical motor is
absorbed.
[0005] As another example, U.S. Pat. No. 6,041,877 to Yamada et al.
discloses a drive unit for a hybrid vehicle. The drive unit
includes an internal combustion engine, a transmission connected to
the internal combustion engine via a clutch and a primary
differential gear for distributing a driving force transmitted from
the transmission to primary driving wheels. The drive unit also
includes a transfer connected to the primary differential gear for
taking out a part of the driving force transmitted from the
transmission to the primary differential gear, a pair of propeller
shafts for transmitting part of the driving force from the transfer
to a secondary differential gear, and an electric motor provided
between the propeller shafts. The drive unit further includes a
pair of clutches, each connecting the electric motor to one of the
pair of propeller shafts.
[0006] As yet another example, U.S. Pat. No. 6,190,282 to Deguchi
et al. discloses a first electric motor connected mechanically to
an engine and a second electric motor connected mechanically
through a clutch to the engine. Drive force is transmitted to drive
wheels through a transmission from the second electric motor. It is
decided whether to connect the clutch on the basis of driving
conditions. The engine is controlled so that the output of the
engine meets the required force when it is decided to connect the
clutch. The first electric motor functions as an electric generator
such that the rotation speed of the engine reaches a target
rotation speed. The clutch is connected when the engine is rotating
at a target rotation speed.
SUMMARY
[0007] A hybrid powertrain system for a vehicle includes a clutch
mechanically coupled with at least one of a primary driveline
assembly and secondary driveline assembly, an electric machine and
a gear set mechanically connected with the electric machine. The
clutch is configured to selectively transfer torque between the
primary driveline assembly and secondary driveline assembly. The
electric machine is configured to selectively provide motive power
to at least one of the primary driveline assembly and secondary
driveline assembly. The gear set is configured to permit
differential rotation between the primary driveline assembly and
secondary driveline assembly.
[0008] A method for operating a power transfer box of an automotive
hybrid powertrain includes providing motive power to at least one
of a primary driveline assembly and secondary driveline assembly by
converting electrical power to motive power, transferring torque
between the secondary driveline assembly and primary driveline
assembly via a clutch and transferring torque between the secondary
driveline assembly and primary driveline assembly via a gear
set.
[0009] While example embodiments in accordance with the invention
are illustrated and disclosed, such disclosure should not be
construed to limit the invention. It is anticipated that various
modifications and alternative designs may be made without departing
from the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic diagram of an embodiment of a
powertrain system for an automotive vehicle.
[0011] FIG. 2 is a schematic diagram of the electric front/rear
auxiliary drive of FIG. 1.
[0012] FIG. 3 is a schematic diagram of another embodiment of an
electric front/rear auxiliary drive.
[0013] FIG. 4 is a schematic diagram of yet another embodiment of
an electric front/rear auxiliary drive.
[0014] FIG. 5 is a schematic diagram of still yet another
embodiment of an electric front/rear auxiliary drive.
DETAILED DESCRIPTION
[0015] Referring now to FIG. 1, a hybrid electric vehicle 10 may
include an engine 12, crank machine 14, transaxle 16 and power
transfer unit 18. The vehicle 10 may also include a front prop
shaft 20, rear prop shaft 22, electric front/rear auxiliary drive
(EFRAD) 24, high voltage battery 26 and power electronics 28. The
vehicle 10 may further include left and right front half-shafts 30,
32, rear axle assembly 34, left and right rear half-shafts 36, 38
and wheel and tire assemblies 40, 42, 44, 46. The operation of
these elements will be described in greater detail below.
[0016] In other embodiments, the vehicle 10 may have a north-south
powertrain configuration and/or a fewer or greater number of
electric machines. Of course, other vehicle configurations are also
possible.
[0017] As apparent to those of ordinary skill, elements shown
adjacent to one another are mechanically coupled. As an example,
the crank machine 14 is mechanically coupled with the engine 12 and
transaxle 16 via, for example, suitable gearing. As another
example, the rear axle assembly 34 is mechanically coupled with the
left and right rear half-shafts 36, 38 and rear prop shaft 22 via,
for example, suitable gearing. Torque may thus be transferred
between the engine 12 and/or crank machine 14 and the EFRAD 24 via
the transaxle 16, power transfer unit 18 and front prop shaft 20.
Likewise, torque may be transferred between the rear axle assembly
34 and the EFRAD 24 via the rear prop shaft 22, etc.
[0018] Certain embodiments of the EFRAD 24, as explained in detail
below, may selectively transfer torque to, from and/or between the
front and rear prop shafts 20, 22. Certain embodiments of the EFRAD
24 may also selectively convert between motive power and electrical
power.
[0019] Referring now to FIGS. 1 and 2, an electric machine 48
includes a stator 50 and rotor 52. The electric machine 48 may
provide electrical power to, or receive electrical power from, the
high voltage battery 26 via the power electronics 28. The stator 50
is fixedly attached, e.g., bolted, with a housing (not shown) of
the EFRAD 24. The rotor 52 is rotatably located, e.g. via bearings,
within a housing (not shown) and about a linking shaft 54. The
linking shaft 54 and the front prop shaft 20 are connected via a
joint 55. The rotor 52 thus rotates relative to the front prop
shaft 22. As apparent to those of ordinary skill, other
arrangements and configurations are also possible.
[0020] A planetary gear set 58 includes a sun gear 60, planet gears
62 and ring gear 64. The sun gear 60 is fixedly attached, e.g.,
press fit, with a leg portion 66 of the rotor 52. The sun gear 60
thus rotates with the front prop shaft 20. In other embodiments,
any suitable gear set, e.g., parallel axis, hypoid, spiral bevel,
etc., may be used. As apparent to those of ordinary skill, the use
of certain gear sets may require, for example, the electric machine
48 to be repositioned within the EFRAD 24, etc.
[0021] An inner carrier 68 is fixedly attached, e.g., press fit,
with the linking shaft 54. The inner carrier 68 carries the planet
gears 62 and inner clutches 70 of the clutch pack 56. The planet
gears 62 and inner clutches 70 thus rotate with the front prop
shaft 20.
[0022] An outer carrier 72 is connected with the rear prop shaft 22
via a joint 74. The outer carrier 72 carries the ring gear 64 and
outer clutches 76 of the clutch pack 56. The ring gear 64 and outer
clutches 76 thus rotate with the rear prop shaft 22.
[0023] In other embodiments, inner clutches and outer clutches may
be carried by any suitable component. For example, outer clutches
may be carried by a leg portion of a rotor or an outer carrier.
Inner clutches may be carried by a leg portion of a rotor. Other
configurations are also possible.
[0024] In a first mode of operation, the engine 12 produces torque
and transmits it to the driveline. The electric machine 48 is
disabled, and therefore provides no reaction torque to the planet
gears 62 via the sun gear 60. As a result, no torque is transferred
from the planet gears 62 to the rear prop shaft 22 via the ring
gear 64. The clutch pack 56 is not compressed. As a result, no
torque is transferred from the linking shaft 54 to the rear prop
shaft 22 via the clutch pack 56. Note that torque from the engine
12 is also being applied to the wheel and tire assemblies 40, 42
through the power transfer unit 18 and front half-shafts 30,
32.
[0025] In a second mode of operation, the engine 12 produces torque
and transmits it to the driveline.
[0026] Electrical power is produced by the electric machine 48 and
is sent to the power electronics 28 to be stored in the high
voltage battery 26 or used for other purposes. The electric machine
48, therefore, applies reaction torque to the planet gears 62 via
the sun gear 60. As a result, torque is transferred from the planet
gears 62 to the rear prop shaft 22 via the ring gear 64. The clutch
pack 56 is not compressed. As a result, no torque is transferred
from the linking shaft 54 to the rear prop shaft 22 via the clutch
pack 56. The torque from the rear prop shaft 22 is transferred to
the left and right rear half-shafts 36, 38 via the rear axle
assembly 34 to drive the wheel and tire assemblies 44, 46.
[0027] In this mode of operation, the electric machine 48 behaves
as a generator. If the mechanical power applied by the electric
machine 48 is -x and the mechanical power applied by the front prop
shaft 20 is y, the mechanical power transferred to the rear prop
shaft 22 is the sum of -x and y (less any system losses.) If the
electric machine 48 behaves as a motor, the mechanical power
transferred to the rear prop shaft 22 is the sum of x and y (less
any system losses.)
[0028] In a third mode of operation, no engine torque is being
transmitted to the driveline. Electrical power from the power
electronics 28 is provided to the electric machine 48. The electric
machine 48, therefore, applies torque to the planet gears 62 via
the sun gear 60, and consequently to the ring gear 64 via the
planet gears 62. As a result, torque is transferred to the front
prop shaft 20 via the planet gears 62 and to the rear prop shaft 22
via the ring gear 64. The clutch pack 56 is not compressed. As a
result, no torque is transferred between the linking shaft 54 and
the rear prop shaft 22 via the clutch pack 56. The torque from the
front prop shaft 20 is transferred to the left and right front
half-shafts 30, 32 via the power transfer unit 18 to drive the
wheel and tire assemblies 40, 42. The torque from the rear prop
shaft 22 is transferred to the left and right rear half-shafts 36,
38 via the rear axle assembly 34 to drive the wheel and tire
assemblies 44, 46.
[0029] In this mode of operation, the electric machine 48 behaves
as a motor. The mechanical power from the machine 48 is distributed
between the front prop shaft 20 and rear prop shaft 22, and the
amount to each is a function of the driveline gear ratios,
including that of the planetary gear set 58 (less any system
losses.) If the electric machine 48 behaves as a generator, the
mechanical power absorbed by the electric machine 48 from the front
prop shaft 20 and rear prop shaft 22 is also a function of the
driveline gear ratios (less any system losses.)
[0030] In a fourth mode of operation, the engine 12 produces torque
and transmits it to the driveline. The electric machine 48 is
disabled, and therefore provides no torque to the planet gears 62
via the sun gear 60. As a result, no torque is transferred from the
planet gears 62 to the rear prop shaft 22. The clutch pack 56 is
compressed to variably transfer torque from the linking shaft 54 to
the rear prop shaft 22. The torque from the rear prop shaft 22 is
transferred to the left and right rear half-shafts 36, 38 via the
rear axle assembly 34 to drive the wheel and tire assemblies 44,
46. Note that torque from the engine 12 is also being applied to
the front wheel and tire assemblies 40, 42 through the power
transfer unit 18 and front half-shafts 30, 32.
[0031] In a fifth mode of operation, the engine 12 produces torque
and transmits it to the driveline.
Electrical power is produced by the electric machine 54 and is sent
to the power electronics 28 to be stored in the high voltage
battery 26 or used for other purposes. The electric machine 48,
therefore, applies reaction torque to the planet gears 62 via the
sun gear 60. As a result, torque is transferred from the planet
gears 62 to the rear prop shaft 22 via the ring gear 64. The clutch
pack 56 is compressed to variably transfer torque from the linking
shaft 54 to the rear prop shaft 22. The torque from the rear prop
shaft 22 is transferred to the left and right rear half-shafts 36,
38 via the rear axle assembly 34 to drive the wheel and tire
assemblies 44, 46. Note that torque from the engine 12 is also
being applied to the front wheel and tire assemblies 40, 42 through
the power transfer unit 18 and the front half-shafts 30, 32.
[0032] In this mode of operation, the electric machine 48 behaves
as a generator. The mechanical power transferred to the rear prop
shaft 22 is a function of the mechanical power absorbed by the
machine 48 and the amount of clutch pack 56 engagement (less any
system losses.) If the electric machine 48 behaves as a motor, the
mechanical power applied to the rear prop shaft 22 is a function of
the mechanical power applied by the machine 48 and the amount of
clutch pack 56 engagement (less any system losses.)
[0033] In a sixth mode of operation, no engine torque is being
transmitted to the driveline. Electrical power from the power
electronics 28 is provided to the electric machine 48. The electric
machine 48, therefore, applies torque to the planet gears 62 via
the sun gear 60, and consequently to the ring gear 64 via the
planet gears 62. As a result, torque is transferred to the front
prop shaft 20 via the planet gears 62 and to the rear prop shaft 22
via the ring gear 64. The clutch pack 56 is compressed to variably
transfer torque between the linking shaft 54 to the rear prop shaft
22, for example, to limit differentiation between the front and
rear prop-shafts 20, 22. The torque from the front prop shaft 20 is
transferred to the left and right front half-shafts 30, 32 via the
power transfer unit 18 to drive the wheel and tire assemblies 40,
42. The torque from the rear prop shaft 22 is transferred to the
left and right rear half-shafts 36, 38 via the rear axle assembly
34 to drive the wheel and tire assemblies 44, 46.
[0034] In this mode of operation, the electric machine 48 behaves
as a motor. The mechanical power from the electric machine 48 is
distributed between the front prop shaft 20 and rear prop shaft 22,
and the amount to each is a function of the driveline gear ratios,
including that of the planetary gear set 58, and the amount of
clutch pack 56 engagement (less any system losses.) If the electric
machine 48 behaves as a generator, the mechanical power absorbed by
the electric machine 48 from the front prop shaft 20 and rear prop
shaft 22 is also a function of the driveline gear ratios and the
amount of clutch pack 56 engagement (less any system losses).
[0035] The clutch pack 56 may provide variable front/rear torque
biasing for regenerative braking and propulsion. As an example, the
torque biasing relative to the electric machine 48 may be 50% front
and 50% rear when the clutch pack 56 is fully compressed and
allowing no speed differentiation between front prop shaft 20 and
rear prop shaft 22. As another example, the torque biasing relative
to the electric machine 48 may be 70% front and 30% rear when the
clutch pack 56 is not compressed and the planetary gear set ratio
provides a 70/30 front/rear torque split. In some embodiments,
variable clutch pack engagement permits variable front/rear torque
biasing from 50% front and 50% rear to 70% front and 30% rear.
Other biasing schemes, however, are also possible, e.g., 90/10,
40/60, etc.
[0036] Referring to FIG. 3, numbered elements of FIG. 3 that differ
by 100 relative to the numbered elements of 2 have similar,
although not necessarily identical, descriptions to the numbered
elements of FIG. 2. In this embodiment, however, the EFRAD 124 has
a configuration that is the reverse of that illustrated in FIG. 2.
That is, the linking shaft 154 is connected with the rear prop
shaft 122 via the joint 174, and the outer carrier 172 is connected
with the front prop shaft 120 via the joint 155.
[0037] As apparent to those of ordinary skill, the operation of the
EFRAD 124 is similar to that of the EFRAD 24 illustrated in FIG. 2
taking into account its reverse configuration. The EFRAD 124,
however, provides the opposite front/rear torque split relative to
the EFRAD 24 illustrated in FIG. 1. If, for example, the EFRAD 24
illustrated in FIG. 1 provides an arrangement with a 70/30
front/rear torque split, a reverse of that arrangement would
provide a 30/70 front/rear torque split, etc.
[0038] Referring to FIG. 4, numbered elements of FIG. 4 that differ
by 200 relative to the numbered elements of 2 have similar,
although not necessarily identical, descriptions to the numbered
elements of FIG. 2. In this embodiment, however, the outer carrier
272 does not carry the ring gear 264. Rather, the ring gear 264 is
fixedly attached, e.g., bolted, with a housing (not shown) of the
EFRAD 224. In other embodiments, any suitable gear set, e.g.,
parallel axis, hypoid, spiral bevel, etc., may be used. As apparent
to those of ordinary skill, the use of certain gear sets may
require, for example, the electric machine 248 to be repositioned
within the EFRAD 224, etc.
[0039] In a first mode of operation, an engine (not shown) produces
torque and transmits it to the driveline. The electric machine 248
is disabled, and therefore provides no reaction torque to the
planet gears 262 via the sun gear 260. As a result, no torque is
transferred to or from the front prop shaft 220 via the planet
gears 262. The clutch pack 256 is not compressed. As a result, no
torque is transferred from the linking shaft 254 to the rear prop
shaft 222 via the clutch pack 256.
[0040] In a second mode of operation, the engine (not shown)
produces torque and transmits it to the driveline. Electrical power
is produced by the electric machine 248 and is sent to power
electronics (not shown) to be stored in a high voltage battery (not
shown) or used for other purposes. The electric machine 248,
therefore, applies reaction torque to the planet gears 262 via the
sun gear 260. As a result, torque produced by the engine is
converted into electrical power. The clutch pack 56 is not
compressed. As a result, no torque is transferred from the linking
shaft 254 to the rear prop shaft 222 via the clutch pack 256.
[0041] In this mode of operation, the electric machine 248 behaves
as a generator. If the electric machine 248 behaves as a motor,
torque transmitted to the driveline is the sum of engine torque and
electric machine torque (minus other loads and system losses).
[0042] In a third mode of operation, no engine torque is being
transmitted to the driveline. Electrical power from the power
electronics (not shown) is provided to the electric machine 248.
The electric machine 48, therefore, applies torque to the planet
gears 262 via the sun gear 260. As a result, torque is transferred
to the front prop shaft 220 via the planet gears 262. The clutch
pack 256 is not compressed. As a result, no torque is transferred
between the linking shaft 254 and the rear prop shaft 222 via the
clutch pack 256.
[0043] In this mode of operation, the electric machine 248 behaves
as a motor. If machine 248 behaves as a generator, mechanical power
absorbed by the electric machine 248 from the front prop shaft 220
is converted to electrical power.
[0044] In a fourth mode of operation, the engine (not shown)
produces torque and transmits it to the driveline. The electric
machine 248 is disabled, and therefore provides no torque to the
planet gears 262 via the sun gear 260. As a result, no torque is
transferred to or from the front prop shaft 220 via the planet
gears 262. The clutch pack 256 is compressed to variably transfer
torque from the linking shaft 254 to the rear prop shaft 222.
[0045] In a fifth mode of operation, the engine (not shown)
produces torque and transmits it to the driveline. Electrical power
is produced by the electric machine 254 and is sent to the power
electronics (not shown) to be stored in the high voltage battery
(not shown) or used for other purposes. The electric machine 248,
therefore, applies reaction torque to the planet gears 262 via the
sun gear 260. As a result, torque produced by the engine (not
shown) is converted into electrical power. The clutch pack 256 is
compressed to variably transfer torque from the linking shaft 254
to the rear prop shaft 222.
[0046] In this mode of operation, the electric machine 248 behaves
as a generator. If the electric machine 248 behaves as a motor,
torque transmitted to the driveline is the sum of engine torque and
electric machine torque (minus other loads and system losses).
[0047] In a sixth mode of operation, no engine torque is being
transmitted to the driveline. Electrical power from the power
electronics (not shown) is provided to the electric machine 248.
The electric machine 248, therefore, applies torque to the planet
gears 262 via the sun gear 260. As a result, torque is transferred
to the front prop shaft 220 via the planet gears 262. The clutch
pack 256 is compressed to variably transfer torque between the
linking shaft 254 and the rear prop shaft 222.
[0048] In this mode of operation, the electric machine 248 behaves
as a motor. If the electric machine 248 behaves as a generator,
mechanical power absorbed by the electric machine 248 from the
front prop shaft 220 and rear prop shaft 222 is converted to
electrical power.
[0049] The clutch pack 256 may provide variable front/rear torque
biasing for regenerative braking and propulsion. As an example, the
torque biasing may be 50% front and 50% rear when the clutch pack
256 is fully compressed and allowing no speed differentiation
between front prop shaft 220 and rear prop shaft 222. As another
example, the torque biasing may be 100% front when the clutch pack
256 is not compressed. In some embodiments, variable clutch pack
engagement allows for variable front/rear torque biasing from 50%
front and 50% rear to 100% front.
[0050] Referring now to FIG. 5, numbered elements of FIG. 5 that
differ by 100 relative to the numbered elements of 4 have similar,
although not necessarily identical, descriptions to the numbered
elements of FIG. 5. In this embodiment, however, the EFRAD 324 has
a configuration that is the reverse of that illustrated in FIG. 4.
That is, the linking shaft 354 is connected with the rear prop
shaft 322 via the joint 374, and the outer carrier 372 is connected
with the front prop shaft 320 via the joint 355.
[0051] As apparent to those of ordinary skill, the operation of the
EFRAD 324 is similar to that of the EFRAD 224 illustrated in FIG. 4
taking into account its reverse configuration. The EFRAD 324,
however, provides the opposite front/rear torque split relative to
the EFRAD 324 illustrated in FIG. 4.
[0052] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *