U.S. patent application number 14/830327 was filed with the patent office on 2017-02-23 for electric drive unit and powertrain system incorporating the same.
This patent application is currently assigned to BORGWARNER INC.. The applicant listed for this patent is BORGWARNER INC.. Invention is credited to Thaddeus Kopp, Larry Pritchard.
Application Number | 20170050508 14/830327 |
Document ID | / |
Family ID | 57964763 |
Filed Date | 2017-02-23 |
United States Patent
Application |
20170050508 |
Kind Code |
A1 |
Pritchard; Larry ; et
al. |
February 23, 2017 |
ELECTRIC DRIVE UNIT AND POWERTRAIN SYSTEM INCORPORATING THE
SAME
Abstract
An electric drive unit for a powertrain system including first
and second drivelines and a primary propulsion system for
translating rotational torque to the first driveline. A motor acts
to generate rotational torque and a pinion is disposed in selective
communication therewith. A differential is interposed between the
pinion and the second driveline of for splitting torque
therebetween. A first planetary is disposed between the motor and
pinion, and a second planetary is disposed between the first
planetary and pinion. A dog clutch interposed between the pinion
and the planetaries is movable between a first position wherein
torque from the motor is translated through the first planetary and
the dog clutch to drive the second driveline at a first drive
ratio, and a second position wherein torque from the motor is
translated through both planetaries and the dog clutch to drive the
second driveline at a second drive ratio.
Inventors: |
Pritchard; Larry; (Macomb,
MI) ; Kopp; Thaddeus; (Oakland Twp., MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BORGWARNER INC. |
Auburn Hills |
MI |
US |
|
|
Assignee: |
BORGWARNER INC.
Auburn Hills
MI
|
Family ID: |
57964763 |
Appl. No.: |
14/830327 |
Filed: |
August 19, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16H 2200/2097 20130101;
B60K 2001/001 20130101; Y10S 903/915 20130101; B60K 17/02 20130101;
B60K 1/00 20130101; F16H 2200/2064 20130101; F16H 2200/2094
20130101; B60Y 2400/80 20130101; B60K 6/50 20130101; F16H 2200/2007
20130101; F16H 3/66 20130101; B60K 6/448 20130101; F16H 2200/0034
20130101; B60Y 2400/421 20130101; B60Y 2400/73 20130101; B60Y
2300/188 20130101; F16H 2200/2035 20130101; Y10S 903/911 20130101;
B60K 6/365 20130101; B60Y 2200/92 20130101; B60K 6/48 20130101;
B60K 17/16 20130101; Y02T 10/62 20130101; B60K 6/387 20130101; B60K
6/52 20130101 |
International
Class: |
B60K 6/50 20060101
B60K006/50; B60K 17/02 20060101 B60K017/02; B60K 6/387 20060101
B60K006/387; B60K 17/16 20060101 B60K017/16; F16H 37/08 20060101
F16H037/08; B60K 6/365 20060101 B60K006/365 |
Claims
1. An electric drive unit for use in a powertrain system including
first and second drivelines and a primary propulsion system for
translating rotational torque to the first driveline, the second
driveline including a pair of wheels, said electric drive unit
comprising: an electric motor that acts to selectively generate
rotational torque; a pinion disposed in selective rotational
communication with said electric motor; a differential interposed
in torque translating relationship between said pinion and the
second driveline of the powertrain system for splitting rotational
torque between said pinion and the wheels of the second driveline;
a first planetary gearset disposed in selective torque translating
relationship between said electric motor and said pinion; a second
planetary gearset disposed in selective torque translating
relationship between said first planetary gearset and said pinion;
and a dog clutch assembly interposed in torque translating
relationship between said pinion and said planetary gearsets,
wherein said dog clutch assembly is movable between a first
position wherein rotational torque from said electric motor is
translated through said first planetary gearset and said dog clutch
assembly to said pinion so as to drive the wheels of the second
driveline at a first predetermined drive ratio, and a second
position wherein rotational torque from said electric motor is
translated through both of said planetary gearsets and said dog
clutch assembly to said pinion so as to drive the wheels of the
second driveline at a second predetermined drive ratio.
2. The electric drive unit as set forth in claim 1, further
including a common ring gear supporting said first planetary
gearset and said second planetary gearset.
3. The electric drive unit as set forth in claim 1, wherein said
first planetary gearset includes a first sun gear, a plurality of
first planet gears disposed in meshing relationship with said first
sun gear, and a first carrier supporting said first planet gears;
and wherein said first carrier rotates concurrently with said
pinion when said dog clutch assembly is in said first position.
4. The electric drive unit as set forth in claim 3, wherein said
first sun gear is operatively attached to said electric motor.
5. The electric drive unit as set forth in claim 3, wherein said
second planetary gearset includes a second sun gear, a plurality of
second planet gears disposed in meshing relationship with said
second sun gear, and a second carrier supporting said second planet
gears; and wherein said second carrier rotates concurrently with
said pinion when said dog clutch assembly is in said second
position.
6. The electric drive unit as set forth in claim 5, wherein said
first carrier of said first planetary gearset is integrally formed
with said second sun gear of said second planetary gearset.
7. The electric drive unit as set forth in claim 1, wherein said
dog clutch assembly is selectively movable to a third position
wherein rotational torque is interrupted between said electric
motor and said pinion.
8. The electric drive unit as set forth in claim 1, further
including an actuator for selectively moving said dog clutch
assembly between said first position and said second position.
9. The electric drive unit as set forth in claim 1, wherein said
differential has a ring supported in rotational communication with
said pinion.
10. The electric drive unit as set forth in claim 9, wherein said
ring and said pinion define a differential reduction gear ratio,
said first planetary gearset defines a first reduction gear ratio,
and said second planetary gearset defines a second gear reduction
ratio; and wherein said first predetermined drive ratio is equal to
the product of said differential reduction gear ratio and said
first reduction gear ratio; and said second predetermined drive
ratio is equal to the product of said differential reduction gear
ratio, said first reduction gear ratio, and said second reduction
gear ratio.
11. The electric drive unit as set forth in claim 10, wherein said
first reduction gear ratio is equal to said second reduction gear
ratio.
12. A powertrain system comprising: a first driveline having a
first pair of wheels; a second driveline having a second pair of
wheels; a primary propulsion system that acts to generate and
translate a first rotational torque only to said first pair of
wheels of said first driveline; an auxiliary propulsion system that
acts to generate and translate a second rotational torque only to
said second pair of wheels of said second driveline, said auxiliary
propulsion system including an electric drive unit having: an
electric motor that acts to selectively generate a third rotational
torque; a pinion disposed in selective rotational communication
with said electric motor; a differential interposed in torque
translating relationship between said pinion and said second pair
of wheels for splitting a fourth rotational torque between said
pinion and said second pair of wheels; a first planetary gearset
disposed in selective torque translating relationship between said
electric motor and said pinion; a second planetary gearset disposed
in selective torque translating relationship between said first
planetary gearset and said pinion; and a dog clutch assembly
interposed in torque translating relationship between said pinion
and said first planetary gearset and said second planetary gearset,
wherein said dog clutch assembly is movable between a first
position wherein the third rotational torque from said electric
motor is translated through said first planetary gearset and said
dog clutch assembly to said pinion so as to drive said second pair
of wheels at a first predetermined drive ratio, and a second
position wherein the third rotational torque from said electric
motor is translated through both of said planetary gearsets and
said dog clutch assembly to said pinion so as to drive said second
pair of wheels at a second predetermined drive ratio.
13. The powertrain system as set forth in claim 12, wherein said
auxiliary propulsion system includes a battery in electrical
communication with said electric motor of said electric drive
unit.
14. The powertrain system as set forth in claim 12, wherein said
primary propulsion system includes an internal combustion
engine.
15. The powertrain system as set forth in claim 12, wherein said
primary propulsion system is further defined as another electric
drive unit.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of Invention
[0002] The present invention relates, generally, to automotive
powertrain systems and, more specifically, to an electric drive
unit for a powertrain system.
[0003] 2. Description of the Related Art
[0004] Conventional automotive vehicles known in the art include a
powertrain system in rotational communication with one or more
drivelines. Typically, the vehicle includes a pair of drivelines,
each defined by a respective pair of opposing wheels. The
powertrain system includes a propulsion system adapted to generate
and selectively translate rotational torque to one or more of the
wheels so as to drive the vehicle. To that end, in conventional
automotive powertrain systems, the propulsion system is typically
realized as an internal combustion engine in rotational
communication with a transmission. The engine generates rotational
torque which is selectively translated to the transmission which,
in turn, translates rotational torque to one or more of the
drivelines. The transmission multiplies the rotational speed and
torque generated by the engine through a series of predetermined
gear sets, whereby changing between gear sets enables the vehicle
to travel at different vehicle speeds for a given engine speed.
[0005] In order to achieve increased fuel economy and improved
engine emissions, so-called "hybrid vehicle technology" has been
increasingly used in powertrain systems known in the related art.
In a hybrid vehicle, the propulsion system typically includes both
a gas-powered internal combustion engine as well as a
battery-powered electric motor, both of which cooperate with the
transmission to generate and translate rotational torque to one or
both vehicle drivelines. Such a hybrid vehicle propulsion system is
configured to optimize the efficiency of the engine and motor,
respectively, so as to minimize fuel consumption and engine
emissions. In addition, the electric motor is frequently also used
as a generator during vehicle braking to charge the battery,
thereby further increasing efficiency and vehicle range.
[0006] With the advent of improved electric motor and battery
technology, automotive vehicles in the related art also frequently
include propulsion systems that omit an internal combustion engine
altogether. So-called "electric vehicle" propulsion systems
typically include a large electric motor in rotational
communication with a transmission and/or differential which, in
turn, is used to translate rotational torque to the wheels of one
or both of the drivelines. Alternatively, in other types of
electric vehicle powertrain systems, smaller individual electric
motors are allocated to each of the driven wheels of the vehicle.
Despite the increasing efficiency of electric propulsion systems in
the related art, problems associated with limited driving distance
and long battery charging time present barriers to widespread
industry implementation of electric propulsion technology. One
solution involves outfitting the electric vehicle with a "range
extender," which is typically realized as a small internal
combustion engine that serves purely as an electric generator and
that is not in rotational communication with the propulsion system.
However, implementation of a range extender is not always feasible
in certain applications where vehicle weight, component packaging,
and zero-emissions requirements are critical.
[0007] Each of the components and systems of the type described
above must cooperate to effectively modulate translation of
rotational torque to the driven wheels of the vehicle. In addition,
each of the components and systems must be designed not only to
facilitate improved performance and efficiency, but also so as to
reduce the cost and complexity of manufacturing vehicles. While
powertrain propulsion systems known in the related art have
generally performed well for their intended use, there remains a
need in the art for a propulsion system that has superior
operational characteristics, a reduced overall packaging size,
reduced parasitic losses, increased efficiency and, at the same
time, that reduces the cost and complexity of manufacturing
vehicles.
SUMMARY OF THE INVENTION
[0008] The present invention overcomes the disadvantages in the
related art in an electric drive unit for use in a powertrain
system including first and second drivelines and a primary
propulsion system for translating rotational torque to the first
driveline. The second driveline includes a pair of wheels. The
electric drive unit includes an electric motor that acts to
selectively generate rotational torque and a pinion disposed in
selective rotational communication with the electric motor. A
differential is interposed in torque translating relationship
between the pinion and the second driveline of the powertrain
system for splitting rotational torque between the pinion and the
wheels of the second driveline. A first planetary gearset is
disposed in selective torque translating relationship between the
electric motor and the pinion. A second planetary gearset is
disposed in selective torque translating relationship between the
first planetary gearset and the pinion. A dog clutch assembly is
interposed in torque translating relationship between the pinion
and the planetary gearsets. The dog clutch assembly is movable
between a first position wherein rotational torque from the
electric motor is translated through the first planetary gearset
and the dog clutch assembly to the pinion so as to drive the wheels
of the second driveline at a first predetermined drive ratio, and a
second position wherein rotational torque from the electric motor
is translated through both of the planetary gearsets and the dog
clutch assembly to the pinion so as to drive the wheels of the
second driveline at a second predetermined drive ratio.
[0009] In addition, the present invention is directed toward a
powertrain system including a first driveline having a first pair
of wheels, a second driveline having a second pair of wheels, a
primary propulsion system that acts to generate and translate
rotational torque only to the first pair wheels of the first
driveline, and an auxiliary propulsion system that acts to generate
and translate rotational torque only to the second pair of wheels
of the second driveline. The auxiliary propulsion system includes
an electric drive unit having an electric motor that acts to
selectively generate rotational torque, and a pinion disposed in
selective rotational communication with the electric motor. A
differential is interposed in torque translating relationship
between the pinion and the second pair of wheels for splitting
rotational torque between the pinion and the second pair of wheels.
A first planetary gearset is disposed in selective torque
translating relationship between the electric motor and the pinion.
A second planetary gearset is disposed in selective torque
translating relationship between the first planetary gearset and
the pinion. A dog clutch assembly is interposed in torque
translating relationship between the pinion and the planetary
gearsets. The dog clutch assembly is movable between a first
position wherein rotational torque from the electric motor is
translated through the first planetary gearset and the dog clutch
assembly to the pinion so as to drive the second pair of wheels at
a first predetermined drive ratio, and a second position wherein
rotational torque from the electric motor is translated through
both of the planetary gearsets and the dog clutch assembly to the
pinion so as to drive the second pair of wheels at a second
predetermined drive ratio.
[0010] In this way, the electric drive unit of the present
invention significantly improves the performance of vehicle
powertrain systems by enabling simple and space-efficient
implementation of battery-powered electric propulsion systems into
vehicles. Moreover, the present invention affords opportunities for
enhanced vehicle features and functionality, such as torque
vectoring and regenerative braking while, at the same time,
providing significant improvements in fuel economy and vehicle
range, acceleration, and cornering stability. Further, the present
invention can be used in connection with a number of different
types of powertrain systems, and can be packaged or otherwise
implemented in a number of different ways. Further still, the
present invention reduces the cost and complexity of manufacturing
vehicles that have superior operational characteristics, such as
high efficiency, reduced weight, and improved emissions, component
packaging, component life, and vehicle drivability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Other objects, features, and advantages of the present
invention will be readily appreciated as the same becomes better
understood after reading the subsequent description taken in
connection with the accompanying drawings wherein:
[0012] FIG. 1 is a schematic plan view of a vehicle powertrain
system including an electric drive unit according to one embodiment
of the present invention.
[0013] FIG. 2 is a sectional view of the electric drive unit
according to one embodiment of the present invention, shown in a
high-range configuration.
[0014] FIG. 3 is a sectional view of the electric drive unit of
FIG. 2 shown in a neutral configuration.
[0015] FIG. 4 is a sectional view of the electric drive unit
according to one embodiment of the present invention, shown in a
low-range configuration.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Referring now to the figures, where like numerals are used
to designate like structure, a vehicle powertrain system is
schematically illustrated at 10 in FIG. 1. The powertrain system 10
includes a first driveline 12 and a second driveline 14. In the
representative embodiment illustrated herein, the first driveline
12 includes a first pair of opposing wheels 16, and the second
driveline 14 includes a second pair of opposing wheels 18. Those
having ordinary skill in the art will recognize this as a
conventional "four wheeled" vehicle design commonly used in
automotive applications. However, as will be appreciated from the
subsequent discussion below, the vehicle could include any number
of drivelines with any suitable number of wheels without departing
from the scope of the present invention. The powertrain system 10
also includes a primary propulsion system 20 and an auxiliary
propulsion system 22. The primary propulsion system 20 acts to
generate and translate rotational torque to the first pair of
wheels 16 of the first driveline 12. Similarly, and as described in
greater detail below, the auxiliary propulsion system 22 acts to
generate and translate rotational torque to the second pair of
wheels 18 of the second driveline 14.
[0017] In the representative example illustrated in FIG. 1, the
primary propulsion system 20 is realized as a convention internal
combustion engine 24 in rotational communication with a
transmission 26. The engine 24 generates rotational torque which is
selectively translated to the transmission 26 which, in turn,
translates rotational torque to the first pair of wheels 16. The
transmission 26 multiplies the rotational speed and torque
generated by the engine 24 and translates rotation to the wheels 16
to so as to drive the vehicle in operation. To that end, the first
driveline 12 includes a pair of continuously-variable joints 28
(shown schematically) that translate rotational torque from the
transmission 26 to the first pair of wheels 16. Those having
ordinary skill in the art will recognize the engine 24 and
transmission 26 of the primary propulsion system 20 as being of the
type employed in conventional "transverse front wheel drive"
powertrain systems 10. Moreover, it will be appreciated that the
engine 24 and/or transmission 26 could be of any suitable type,
configured in any suitable way sufficient to generate and translate
rotational torque to the first driveline 12, without departing from
the scope of the present invention. Further, it will be appreciated
that the primary propulsion system 20 could be configured
differently, or omitted entirely, without departing from the scope
of the present invention. By way of non-limiting example, the
primary propulsion system 20 could employ what is commonly referred
to in the related art as a "hybrid engine," whereby rotational
torque translated to the first driveline 12 is generated by the
engine 24 as well as by one or more discrete electric motors (not
shown, but generally known in the art).
[0018] As noted above, the powertrain system 10 also includes an
auxiliary propulsion system 22. In the representative example
illustrated in FIG. 1, the auxiliary propulsion system 20 is
realized as an electric drive unit, generally indicated at 30 and
according to the present invention. As will be appreciated from the
subsequent description below, the electric drive unit 30 can be
used in connection with any suitable type of vehicle powertrain
system 10, with or without the use of a conventional internal
combustion engine 24, without departing from the scope of the
present invention. By way of example, it is conceivable that both
the primary propulsion system 20 and the auxiliary propulsion
system 22 could be realized as independent electric drive units 30.
Similarly, the primary propulsion system 20 of the powertrain
system 10 could be omitted entirely. Moreover, while the present
invention is adapted for use with automotive passenger vehicles, it
will be appreciated that electric drive unit 30 could be used in
connection with any suitable type of vehicle, such as heavy-duty
trucks, trains, airplanes, ships, construction vehicles or
equipment, military vehicles, recreational vehicles, or any other
type of vehicle that could benefit from electrically-powered torque
generation.
[0019] Referring now to FIGS. 2-4, the electric drive unit 30 of
the present invention includes an electric motor 32, a pinion 34, a
differential 36, a first planetary gearset 38, a second planetary
gearset 40, and a dog clutch assembly 42. In the representative
embodiment illustrated herein, the electric drive unit 30 also
includes a main housing 44 supporting, defining, and/or operatively
attached to each of these components, as described in greater
detail below.
[0020] The electric motor 32 is supported in the main housing 44,
such as by one or more bearings, generically indicated at 46 (see
FIG. 2). The electric motor 32 acts to selectively generate
rotational torque used to drive the second pair of wheels 18 of the
second driveline 14, as described in greater detail below. To that
end, and in one embodiment of the present invention, the auxiliary
propulsion system 22 includes a battery 48 and a controller 50 both
in electrical communication with the electric drive unit 30 (see
FIG. 1). The battery 48 is used to power the electric motor 32 in
operation and may be of any suitable type, size, or configuration.
The controller 50, sometimes referred to in the related art as an
"electronic control module," is in electrical communication with
the electric motor 32, and may be configured to modulate, actuate,
or otherwise control the dog clutch assembly 42 so as to control
translation of rotational torque between the electric motor 32 and
the second pair of wheels 18, as described in greater detail below.
Advantageously, the auxiliary propulsion system 22 may be
configured so that the electric motor 32 also functions as a
generator used to charge the battery 48, such as by regenerative
breaking. Moreover, is also conceivable that the battery 48 could
be charged while the vehicle is parked, using so-called "plug-in
hybrid" technology known in the related art.
[0021] It will be appreciated that the electric motor 32 could be
of any suitable type or configuration sufficient to generate
rotational torque using power from the battery 48 without departing
from the scope of the present invention. By way of non-limiting
example, it is conceivable that the electric motor 32 could be
realized as a DC traction motor or an AC induction motor. As will
be appreciated from the subsequent description below, the specific
configuration of the electric motor 32 may be determined based on
specific operational requirements of the powertrain system 10, such
as vehicle speed, curb weight, payload capacity, operating
environment, etc.
[0022] As noted above, the electric drive unit 30 includes a pinion
34 disposed in selective rotational communication with the electric
motor 32. The pinion 34 is supported in the main housing 44, such
as by one or more bearings 46 (see FIG. 2). More specifically, the
pinion 34 includes a pinion gear 52 and a pinion shaft 54. The
pinion shaft 54 is coupled to and rotates with the pinion gear 52
and is disposed in selective rotational communication with the dog
clutch assembly 42. The pinion gear 52 is disposed in meshing
engagement with the differential 36 so as to translate rotational
torque between the electric motor 32 and the wheels 18 of the
second driveline 14. To that end, the differential 36 is interposed
in torque translating relationship between the pinion 34 and the
second driveline 14 of the powertrain system 10 for splitting
rotational torque between the pinion 34 and the wheels 18 of the
second driveline 14. More specifically, the differential 36
includes a ring 56, a pair of output shafts 58, and a differential
subassembly, generally indicated at 60. The ring 56 is supported in
meshing engagement with the pinion gear 52. Thus, the ring 56 is
supported in rotational communication with the pinion 34.
Similarly, the outputs 58 of the differential 36 are each rotatably
supported in the differential 36, such as by bearings 46 (see FIG.
2), and are each disposed in rotational communication with one of
the wheels 18 of the second driveline 14. To that end, in one
embodiment, the electric drive unit 30 includes an output flange 62
operatively attached to each of the output shafts 58 of the
differential 36 (see FIG. 1). The output flanges 62 facilitate
simple connection to the second pair of wheels 18, such as by
another set of continuously-variable joints 28. However, those
having ordinary skill in the art will appreciate that the electric
drive unit 30 could be designed in any suitable way sufficient to
translate rotational torque from the output shafts 58 to the second
pair of wheels 18 of the second driveline 14, with or without the
use of output flanges 62, without departing from the scope of the
present invention.
[0023] The differential subassembly 60 is also rotatably supported
by the differential 36, such as by bearings 46 (see FIG. 2), and is
used to split rotational torque between the ring 56 and the output
shafts 58, as noted above. While the differential subassembly 60
illustrated herein is of a conventional configuration and utilizes
an arrangement of bevel gears to split torque between the wheels 18
of the second driveline 14 (not shown in detail, but generally
known in the art), those having ordinary skill in the art will
appreciated that the differential subassembly 60 could be of any
suitable type or configuration sufficient to split rotational
torque between the pinion 34 and the wheels 18 of the second
driveline 14 without departing from the scope of the present
invention. By way of non-limiting example, the differential 36
could be of a so-called "limited-slip" configuration utilizing what
is commonly referred to as "torque sensing" gears and/or and
arrangement of one or more frictional clutch assemblies to control
torque split between the wheels 18 of the second driveline 14 in a
predetermined or selectively adjustable manner (not shown, but
generally known in the related art).
[0024] As noted above, the electric drive unit 30 also includes a
pair of planetary gearsets 38, 40. The first planetary gearset 38
is disposed in selective torque translating relationship between
the electric motor 32 and the pinion 34. Similarly, the second
planetary gearset 40 is disposed in selective torque translating
relationship between the first planetary gearset 38 and the pinion
34. Further, the dog clutch assembly 42 is interposed in torque
translating relationship between the pinion 34 and the planetary
gearsets 38, 40. The dog clutch assembly 42 is selectively movable
between a first position 42A (see FIG. 2) and a second position 42B
(see FIG. 4). In one embodiment, the dog clutch assembly 42 is also
selectively movable to a third position 42C (see FIG. 3), as
described in greater detail below. When the dog clutch assembly 42
is in the first position 42A (see FIG. 2), rotational torque from
the electric motor 32 is translated through the first planetary
gearset 38 and the dog clutch assembly 42 to the pinion 34 so as to
drive the wheels 18 of the second driveline 14 at a first
predetermined drive ratio DR1, as described in greater detail
below. Conversely, when the dog clutch assembly 42 is in the second
position 42B (see FIG. 4), rotational torque from the electric
motor 32 is translated through both of the planetary gearsets 38,
40 and also through the dog clutch assembly 42 to the pinion 34 so
as to drive the wheels 18 of the second driveline 14 at a second
predetermined drive ratio DR2, as described in greater detail
below.
[0025] The first planetary gearset 38 includes a first sun gear 64,
a plurality of first planet gears 66 disposed in meshing
relationship with the first sun gear 64, and a first carrier 68
supporting the first planet gears 66. The first carrier 68 rotates
concurrently with the pinion 34 when the dog clutch assembly 42 is
in the first position 42A (see FIG. 2). In one embodiment, the
electric motor 32 includes a motor output shaft, generally
indicated at 70, which is operatively attached to the first sun
gear 64 of the first planetary gearset 38, such as with a keyed
engagement therebetween (not shown in detail, but generally known
in the related art). Thus, the output shaft 70 of the electric
motor 32 is coupled to and rotates concurrently with the first sun
gear 64 of the first planetary gearset 38. However, those having
ordinary skill in the art will appreciate that the first sun gear
64 could be operatively attached the electric motor 32 in any
suitable way without departing from the scope of the present
invention. Moreover, it will be appreciated that the first
planetary gearset 38 could be configured in a number of different
ways sufficient to selectively translate rotational torque between
the electric motor 32 and the pinion 34, as noted above, without
departing from the scope of the present invention.
[0026] In one embodiment, the second planetary gearset 40 includes
a second sun gear 72, a plurality of second planet gears 74
disposed in meshing relationship with the second sun gear 72, and a
second carrier 76 supporting the second planet gears 74. The second
carrier 76 rotates concurrently with the pinion 34 when the dog
clutch assembly 42 is in the second position 42B (see FIG. 4). It
will be appreciated that the second planetary gearset 40 could be
configured in a number of different ways sufficient to selectively
translate rotational torque between the first planetary gearset 38
and the pinion 34, as noted above, without departing from the scope
of the present invention.
[0027] In the representative embodiment of the electric drive unit
30 depicted in FIGS. 2-4, the second sun gear 72 of the second
planetary gearset 40 is integrally formed with the first carrier 68
of the first planetary gearset 38. It will be appreciated that this
configuration advantageously optimizes the overall packaging size
of the electric drive unit 30 and contributes to simplified
component assembly during manufacturing. Similarly, in one
embodiment, the first planetary gearset 38 and the second planetary
gearset 40 are both supported in meshing engagement with a common
ring gear 78 which, in turn, is supported in the main housing 44,
thereby further simplifying the complexity of assembling the
electric drive unit 30. However, those having ordinary skill in the
art will appreciate that the planetary gearsets 38, 40 could be
arranged or otherwise configured in any suitable way sufficient to
cooperate with the dog clutch assembly 42 so as to effect selective
translation of rotational torque between the electric motor 32 and
the pinion 34, as noted above, without departing from the scope of
the present invention.
[0028] It will be appreciated that the planetary gearsets 38, 40
and the differential 36 can each be configured so as to adjust the
rotational speed and/or torque generated by the electric motor 32
so as to effect translation of rotational torque to the wheels 18
of the second driveline 14 such that particularly advantageous
electric motor 32 operating conditions can be utilized under
certain predetermined vehicle operating conditions, thereby
optimizing the efficiency of the entire powertrain system 10.
Specifically, the ring 56 of the differential 36 and the pinion
gear 52 of the pinion 34 define a differential reduction gear ratio
GRD, the first sun gear 64 and the first planet gears 66 of the
first planetary gearset 38 define a first reduction gear ratio GR1,
and the second sun gear 72 and the second planet gears 74 of the
second planetary gearset 40 define a second reduction gear ration
GR2. The first drive ratio DR1 is equal to the product of the
differential reduction gear ratio GRD and the first reduction gear
ratio GR1. Expressed differently, DR1=GRD*GR1. Similarly, the
second drive ratio DR2 is equal to the product of the differential
reduction gear ratio GRD, the first reduction gear ratio GR1, and
the second reduction gear ration GR2. Expressed differently,
DR2=GRD*GR1*GR2. Thus, these ratios can be adjusted depending on
the application of the powertrain system 10, whereby different
ratios may be implemented for vehicles with different requirements
in terms of weight, top speed, acceleration, and the like. The
inventors have found that a first reduction gear ratio GR1 of
between 2.6:1 and 5.0:1, a second reduction gear ratio GR2 of
between 2.6:1 and 5.0:1, and a differential reduction gear ratio of
between 2.5:1 and 4.0:1 are particularly advantageous for
powertrain systems 10 implemented in connection with automotive
passenger vehicle powertrain systems 10, in that substantial
compromise is achieved between overall component size and packaging
complexity, vehicle speed and payload capacity, and efficient motor
operating range utilization. In one embodiment, the first reduction
gear ratio GR1 is equal to the second reduction gear ratio GR2.
Expressed differently, GR1=GR2.
[0029] It will be appreciated that the configuration of the drive
ratios DR1, DR2 described above effect selective operation of the
electric drive unit 30 between a so-called "high range" when the
dog clutch assembly 42 is in the first position 42A (see FIG. 2)
and a "low range" when the dog clutch assembly 42 is in the second
position 42B (see FIG. 4). As noted above, in one embodiment, the
dog clutch assembly 42 is also selectively movable to a third
position 42C, wherein rotational torque is interrupted between the
electric motor 32 and the pinion 34 (see FIG. 3). Those having
ordinary skill in the art will appreciate that interruption between
the electric motor 32 and pinion 34 defines a so-called "neutral"
or "free-wheel" configuration which may be advantageously
implemented in certain types of powertrain systems 10, such as
those utilizing a DC traction motor configuration for the electric
motor 32 whereby the third position 42C can be utilized to increase
the efficiency of the second driveline 14 by reducing
counter-electromotive force (sometimes referred to in the related
art as "back EMF") at relatively high vehicle speeds or during
other predetermined vehicle operating conditions. However, those
having ordinary skill in the art will appreciate that the dog
clutch assembly 42 could be realized without a discrete third
position 42C, depending on the specific requirements of the
powertrain system 10, without departing from the scope of the
present invention.
[0030] In order to effect movement of the dog clutch assembly 42
between the positions 42A, 42B, 42C, the electric drive unit 30 may
include an actuator, generally indicated at 80. As illustrated in
FIGS. 2-4, the actuator 80 is supported within the main housing 44
and is used to move a slider 82 which, in turn, moves the dog
clutch assembly 42 between the positions 42A, 42B, 42C. In the
representative embodiment illustrated throughout the figures, the
actuator 80 is realized as a ram actuated such as via pressurized
hydraulic fluid (not shown in detail, but generally known in the
related art). However, those having ordinary skill in the art will
appreciate that the actuator 80 could be of any suitable type or
configuration sufficient to move the dog clutch assembly 42 between
the positions 42A, 42B, 42C, without departing from the scope of
the present invention. By way of non-limiting example, the actuator
80 could be an electric linear actuator driven via the controller
50 (see FIG. 1; not shown in detail, but generally known in the
related art).
[0031] As noted above, selective actuation of the actuator 80 urges
the slider 82 which, in turn, moves the dog clutch assembly 42
between the positions 42A, 42B, 42C. To that end, in one
embodiment, the dog clutch assembly 42 includes an interface
coupling 84, a first engagement coupling 86, a second engagement
coupling 88, and a collar assembly 90. The interface coupling 84 is
operatively attached to and rotates concurrently with the pinion
shaft 54. The collar assembly 90 is operatively attached to and
moves concurrently with the slider 82 (compare FIGS. 2-4). The
first engagement coupling 86 is operatively attached to and rotates
concurrently with the first carrier 68 of the first planetary
gearset 38. Similarly, the second engagement coupling 88 is
operatively attached to and rotates concurrently with the second
carrier 76 of the second planetary gearset 40. The collar assembly
90 has an inner tooth arrangement, generally indicated at 90A, and
the couplings 84, 86, 88 each have an outer tooth arrangement,
generally indicated at 84A, 86A, 88A, respectively. The inner tooth
arrangement 90A of the collar assembly 90 is meshed with and
travels along the outer tooth arrangement 84A of the interface
coupling 84 as the slider 82 moves between the positions 42A, 42B,
42C. When the slider 82 moves the dog clutch assembly 42 to the
first position 42A, the inner tooth arrangement 90A of the collar
90 simultaneously engages the outer tooth arrangement 84A of the
interface coupling 84 and the outer tooth arrangement 86A of the
first engagement coupling 86 (see FIG. 2). Similarly, when the
slider 82 moves the dog clutch assembly 42 to the second position
42B, the inner tooth arrangement 90A of the collar 90
simultaneously engages the outer tooth arrangement 84A of the
interface coupling 84 and the outer tooth arrangement 88A of the
second engagement coupling 88 (see FIG. 4). Further, when the
slider 82 moves the dog clutch assembly 42 to the third position
42C, the inner tooth arrangement 90A of the collar 90 engages the
outer tooth arrangement 84A of the interface coupling 84 and is
spaced from both the outer tooth arrangement 86A of the first
engagement coupling 86 and the outer tooth arrangement 88A of the
second engagement coupling 88 (see FIG. 3). Those having ordinary
skill in the art will recognize that the dog clutch assembly 42
described herein translates rotational torque between the pinion 34
and the planetary gearsets 38, 42 via interference engagement of
the tooth arrangements 84A, 86A, 88A, 90A. This configuration
significantly avoids frictional parasitic losses in operation and
contributes to increased efficiency of the electric drive unit 30.
Further, it will be appreciated that the dog clutch assembly 42
could be supported, configured, or otherwise oriented in a number
of different ways, utilizing any suitable arrangement or
combination of components sufficient to effect selective
translation of rotational torque between the pinion 34 and the
planetary gearsets 38, 42 via interference engagement, without
departing from the scope of the present invention. In one
embodiment, each of the engagement couplings 86, 88 includes a
synchro, generally indicated at 92, for facilitating smooth
engagement with the collar 90 as the slider 82 moves the dog clutch
assembly 42 between positions 42A, 42B, 42C (not shown in detail,
but generally known in the art).
[0032] In this way, the electric drive unit 30 and powertrain
system 10 of the present significantly improves the performance of
vehicles by enabling simple and space-efficient implementation of
battery-powered electric auxiliary propulsion systems 22.
Specifically, it will be appreciated that the present invention
allows vehicles to benefit from advantages traditionally reserved
for hybrid or electric vehicles, such as regenerative breaking and
responsive torque availability at a broad range of vehicle
operating speeds. Thus, an otherwise conventional
"front-wheel-drive" vehicle with an internal combustion engine 24
can be outfitted with the electric drive unit 30 according to the
present invention in a simple and cost effect manner while, at the
same time, providing significant improvements in fuel
economy/range, acceleration, traction, and "four-wheel-drive"
functionality. Further, the electric drive unit 30 and powertrain
system 10 of the present invention reduce the cost and complexity
of manufacturing vehicles that have superior operational
characteristics, such as high efficiency, reduced weight, and
improved emissions, component packaging, component life, and
vehicle drivability.
[0033] The invention has been described in an illustrative manner.
It is to be understood that the terminology which has been used is
intended to be in the nature of words of description rather than of
limitation. Many modifications and variations of the invention are
possible in light of the above teachings. Therefore, within the
scope of the appended claims, the invention may be practiced other
than as specifically described.
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