U.S. patent application number 13/465349 was filed with the patent office on 2013-11-07 for modular hybrid transmission with a one way clutch.
This patent application is currently assigned to FORD GLOBAL TECHNOLOGIES, LLC. The applicant listed for this patent is Daniel Scott Colvin, Bernard D. Nefcy, Walter Joseph Ortmann. Invention is credited to Daniel Scott Colvin, Bernard D. Nefcy, Walter Joseph Ortmann.
Application Number | 20130296108 13/465349 |
Document ID | / |
Family ID | 49384660 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130296108 |
Kind Code |
A1 |
Ortmann; Walter Joseph ; et
al. |
November 7, 2013 |
Modular Hybrid Transmission with a One Way Clutch
Abstract
A vehicle transmission system having a combustion engine, an
electric motor and a transmission includes a first clutch
operatively connected between the engine and the motor and a one
way clutch. The one way clutch is connected in parallel with the
first clutch that permits the engine to increase speed with the
clutch disengaged until the engine speed matches the motor speed.
The engine provides positive torque through the one way clutch to
the motor and transmission upon matching the motor speed. The first
clutch and the one way clutch may be a hybrid rocker one way
clutch.
Inventors: |
Ortmann; Walter Joseph;
(Saline, MI) ; Colvin; Daniel Scott; (Farmington
Hills, MI) ; Nefcy; Bernard D.; (Novi, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ortmann; Walter Joseph
Colvin; Daniel Scott
Nefcy; Bernard D. |
Saline
Farmington Hills
Novi |
MI
MI
MI |
US
US
US |
|
|
Assignee: |
FORD GLOBAL TECHNOLOGIES,
LLC
Dearborn
MI
|
Family ID: |
49384660 |
Appl. No.: |
13/465349 |
Filed: |
May 7, 2012 |
Current U.S.
Class: |
477/5 ;
180/65.275; 903/902 |
Current CPC
Class: |
Y10S 903/913 20130101;
Y02T 10/62 20130101; B60W 2710/02 20130101; Y10T 477/26 20150115;
B60W 10/06 20130101; B60W 2510/081 20130101; Y02T 10/6252 20130101;
B60K 6/383 20130101; B60W 10/02 20130101; B60K 6/48 20130101; B60W
2510/0638 20130101; B60W 20/40 20130101; B60K 2006/4825 20130101;
Y02T 10/6221 20130101 |
Class at
Publication: |
477/5 ;
180/65.275; 903/902 |
International
Class: |
B60W 20/00 20060101
B60W020/00 |
Claims
1. A transmission system having a combustion engine, an electric
motor and a transmission, the system comprising: a clutch
operatively connected between the engine and the motor; and a one
way clutch connected in parallel with the clutch that permits the
engine to increase speed with the clutch disengaged until the
engine speed matches a motor speed, wherein the engine provides
positive torque through the one way clutch to the motor and
transmission upon matching the motor speed.
2. The transmission system of claim 1 wherein the clutch is a wet
clutch that is shifted by hydraulic pressure from a hydraulic
pump.
3. The transmission system of claim 1 wherein upon the engine speed
matches the motor speed, the one way clutch limits a speed of
rotation of the engine to a speed of rotation of the motor by over
running the one way clutch in the event the speed of rotation of
the engine exceeds the speed of rotation of the motor.
4. The transmission system of claim 1 wherein the one way clutch is
a hybrid one way clutch that has rockers that may be shifted to
engage the clutch in one rotational direction.
5. The transmission system of claim 4 wherein the clutch is a
second hybrid one way clutch that has rockers that may be shifted
to engage the clutch in one rotational direction.
6. The transmission system of claim 1 wherein the clutch is a
hybrid one way clutch that has rockers that may be shifted to
engage the clutch in one rotational direction.
7. A transmission system for a vehicle that has a combustion
engine, an electric motor and a transmission connected in series,
the transmission system comprising: a one way clutch that slips in
a first rotational drive direction; and a hybrid one way clutch
having selectively shifted rockers is connected in parallel to the
one way clutch between the engine and the motor, the rockers are
actuated when an engine speed matches a motor speed to shift the
rockers from a bidirectional slip condition to a one way slip
condition locked in the first rotational drive direction.
8. The transmission system of claim 7 wherein the rockers when
actuated causes the hybrid one way clutch to slip in a second
rotational drive direction.
9. The transmission system of claim 7 wherein when the engine speed
matches the motor speed the one way clutch connects the engine to
the transmission to transmit torque to a driveline of the
vehicle.
10. The transmission system of claim 7 wherein the one way clutch
is a second hybrid one way clutch that locks prior to when the
engine speed matches the motor speed.
11. A method of operating a transmission system for a vehicle that
has a combustion engine, an electric motor and a transmission
connected in series, a first clutch operatively connected between
the engine and the motor, and a one way clutch connected in
parallel with the first clutch, the method comprising: initiating
an engine start operation; disengaging the first clutch to
disconnect the engine from the electric motor; and engaging the one
way clutch when an engine speed matches a motor speed.
12. The method of claim 11 wherein the first clutch is a hybrid one
way clutch having rockers that are selectively shifted to connect
the engine to the electric motor.
13. The method of claim 11 wherein the first clutch is a
hydraulically actuated disconnect clutch.
14. The method of claim 11 wherein the first clutch is a hybrid one
way clutch with electrically shifted rockers.
15. The method of claim 14 wherein the one way clutch is a second
hybrid one way clutch with electrically shifted rockers.
16. The method of claim 11 wherein the one way clutch is a hybrid
one way clutch with electrically shifted rockers.
Description
TECHNICAL FIELD
[0001] This disclosure relates to a transmission for a vehicle that
has a combustion engine that is connected by a one way clutch to an
electric motor and a transmission gear box.
BACKGROUND
[0002] Hybrid electric vehicles may connect a combination of an
internal combustion engine with an electric motor in series to
provide the power needed to propel a vehicle for improved fuel
economy over a conventional vehicle. One way to improve the fuel
economy of a hybrid vehicle is to shut down the engine during times
that the engine operates inefficiently and to use the electric
motor to provide all of the power needed to propel the vehicle. The
engine must start in a quick and smooth manner that is nearly
transparent to the driver in the event the driver wants more power
than the electric motor can provide or if the battery becomes
depleted.
[0003] A Modular Hybrid Transmission (MHT) is a pre-transmission
parallel hybrid with a disconnect clutch positioned between the
electric motor and the engine. The disconnect clutch is fully
integrated into the transmission hydraulic system and is actuated
by a linear solenoid. MHT hybrids represent one approach to
providing a torque path for rear wheel drive vehicles.
[0004] In a MHT system, the engine may be started independently of
the motor that is driving the vehicle. Once the engine is up to
speed, the disconnect clutch may be commanded to engage to allow
the engine to deliver torque to the transmission. The motor speed
may be below a minimum speed required to deliver robust line
pressure before the engine start request. If the line pressure is
insufficient, application of the disconnect clutch may become
unpredictable.
[0005] Timing the application of the disconnect clutch is important
with a MHT design. The clutch is a wet friction clutch that must be
stroked before torque can be transmitted. The added flow volume for
stroking the clutch with the oil pump operating at low speed may
cause an undesired drop in line pressure that may create a
driveline disturbance. The drop in line pressure may have a
deleterious effect on controlling the pressure applied by the
launch clutch or torque converter bypass clutch.
[0006] The above problems and other problems relating to modular
hybrid systems are addressed by this disclosure as summarized
below.
SUMMARY
[0007] In the MHT design, the engine is never required to operate
at a higher speed than the motor. When the engine is off, the motor
may operate at a higher speed than the engine. A one way clutch
(OWC) may be provided that is connected between the engine and the
motor in parallel with a disconnect clutch. The one way clutch
prevents the engine from over-running the motor. The one way clutch
eliminates the need to synchronously transfer torque from the motor
to the engine as the engine increases speed. This one way clutch
simplifies the process of applying the clutch.
[0008] Alternatively, the friction clutch may be eliminated and a
hybrid rocker one way clutch (HROWC) may be placed in series with
the OWC. The HROWC is an electrically controlled device that is
shifted between "applied" and "not applied" states. The rockers are
open and torque is not transmitted in either direction when the
HROWC is not applied. When the HROWC is applied, the rockers are
pulled in to allow slip in one direction and full engagement in the
other direction. The HROWC is applied when the engine speed matches
motor speed so that the engine is locked with the motor by the two
OWCs. When the HROWC is not applied, the engine is allowed to
operate at speeds less than the motor. One advantage of this
concept is lower spin losses of the open clutch during electric
drive.
[0009] According to one aspect of this disclosure, a transmission
system is provided for a vehicle that has a combustion engine, an
electric motor and a transmission connected in series. The
transmission system comprises a disconnect clutch operatively
connected between the engine and the motor, and a one way clutch
connected in parallel with the disconnect clutch that allows the
engine to increase speed with the disconnect clutch disengaged
until it matches the motor speed. After matching speeds, the engine
provides positive torque to the motor and transmission.
[0010] According to other aspects of the disclosure, the disconnect
clutch may be a wet clutch that is shifted by hydraulic pressure
from a hydraulic pump. The one way clutch connects the engine to
the transmission to transmit torque to a driveline of the vehicle
when the engine speed matches the motor speed. The speed of
rotation of the engine is limited by the OWC to the motor speed.
The one way clutch may be a hybrid one way clutch that has rockers
that may be shifted to engage the clutch in one rotational
direction.
[0011] According to another aspect of the disclosure, a
transmission system is disclosed for a vehicle that has a
combustion engine, an electric motor and a transmission connected
in series. The transmission system comprises a one way clutch that
slips in a first rotational drive direction, and a hybrid one way
clutch having selectively shifted rockers. The hybrid clutch is
connected in parallel to the one way clutch between the engine and
the motor. The rockers are actuated when the engine speed matches
the motor speed to shift the rockers from a bidirectional slip
condition to a one way slip condition locked in the first
rotational drive direction.
[0012] According to further aspects of the disclosure, the rockers
when actuated may cause the hybrid clutch to slip in a second
rotational drive direction. The one way clutch connects the engine
to the transmission to transmit torque to a driveline of the
vehicle when the engine speed matches the motor speed.
[0013] According to another aspect of the disclosure as it relates
to a method of operating a transmission system for a vehicle that
has a combustion engine, an electric motor and a transmission
connected in series. The transmission system further includes a
first clutch operatively connected between the engine and the motor
and a one way clutch connected in parallel with the first clutch.
The method includes the steps of initiating an engine start
operation, disengaging the first clutch to disconnect the engine
from the electric motor, and engaging the one way clutch when the
engine speed matches or exceeds the motor speed.
[0014] According to other aspects of the method, the first clutch
may be a hybrid one way clutch having rockers that are selectively
shifted to connect the engine to the electric motor. The first
clutch may be a hydraulically actuated disconnect clutch. The
method may further comprise applying the maximum pressure to the
first clutch.
[0015] The above aspects of the disclosure and other aspects will
be better understood in view of the attached drawings and the
following detailed description of the illustrated embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a diagrammatic representation of a modular hybrid
transmission with a one way clutch connected in parallel with a
disconnect clutch;
[0017] FIG. 2 is a graph of an engine start control showing engine
and motor speed and engine and motor torque through seven modes of
operation; and
[0018] FIG. 3 is a diagrammatic representation of an alternative
embodiment of a modular hybrid transmission with a one way clutch
or a hybrid rocker one way clutch connected in parallel with an
oppositely oriented hybrid rocker one way clutch.
DETAILED DESCRIPTION
[0019] The illustrated embodiments are disclosed with reference to
the drawings. However, it is to be understood that the disclosed
embodiments are intended to be merely examples that may be embodied
in various and alternative forms. The figures are not necessarily
to scale and some features may be exaggerated or minimized to show
details of particular components. The specific structural and
functional details disclosed are not to be interpreted as limiting,
but as a representative basis for teaching one skilled in the art
how to practice the disclosed concepts.
[0020] Referring to FIG. 1, a modular hybrid transmission (MHT)
system 10 is diagrammatically illustrated and includes an electric
fraction motor 12, a combustion engine 14, and a transmission gear
box 16. A disconnect clutch 20 is operatively disposed between the
engine 14 and the motor 12 to selectively connect and disconnect
the engine 14 from the motor 12. A damper 22 may also be provided
between the disconnect clutch 20 and the engine 14. A one way
clutch (OWC) 24 is connected in parallel with the disconnect clutch
20 between the damper 22 and the electric motor 12.
[0021] A starter motor 26 may be provided for starting the engine
14 in the embodiment shown in FIG. 1. It should be understood that
other starter arrangements may be provided that may benefit from
the concepts disclosed.
[0022] A launch clutch 28 is provided between the motor 12 and the
transmission gearbox 16. The launch clutch 28 provides torque to
the transmission gear box 16 from either or both of the motor 12 or
engine 14. In the embodiment of FIG. 1, no torque converter is
included in the gearbox. A torque converter could be included in
the combination and used in place of the launch clutch 28.
[0023] Referring to FIG. 2, a graph of engine and motor torque and
engine and motor speed during engine start and engine shut down is
provided for a transmission system 10 made in accordance with one
embodiment of this disclosure. In mode 1, the motor 12 is providing
torque for traction and the engine 14 is not in operation. The
vehicle in mode 1 is preparing to start the engine 14 that is
indicated by the line 30 that shows the engine speed increasing.
The oscillating line 32 overlaid on line 30 indicates that the rate
of increase varies. The speed of the motor is illustrated by line
34 and is generally unchanged except that the motor speed may
increase a small amount during engine start because of the need to
maintain fluid pressure in the system or to allow a downstream
clutch to slip and provide torsional isolation relative to the
driveline.
[0024] Torque from the motor 12 is illustrated by line 36 that
shows positive torque is provided by the motor 12 through the first
mode. Engine torque illustrated by line 38 in mode 1 is at zero. As
the engine speed 30 increases speed, and enters mode 2 a small
amount of torque is produced by the engine 14. In mode 3, the
engine speed continues to increase and approaches the same speed as
the motor 12 as shown on line 34. When the engine speed matches the
motor speed, mode 3 begins in which torque transfer from the engine
14 begins while torque from the motor 12 is reduced. As used in
this disclosure, the term "matches" should be understood to mean
that the speed of rotation of the engine 14 is within 5 rpm
compared to the motor 12. In mode 3, the engine speed 30 is shown
to match the motor speed 34 and motor torque 36 is reduced while
the engine torque 38 increases.
[0025] Line 40 illustrates operation of the disconnect clutch 20.
In mode 4 the disconnect clutch 20 is beginning to be applied.
However, it should be understood that the disconnect clutch 20
could be applied earlier in mode 3. The disconnect clutch 20 is
applied to lock-up the motor 12 and engine 14. The engine 14 in
mode 4 provides positive torque to drive the vehicle and also
produces torque that is used to charge the battery (not shown).
[0026] In mode 4 with the vehicle being powered by the combustion
engine 14 pressure applied to the disconnect clutch 20 is shown by
line 40 to be initially at a normal operational level. The pressure
command is reduced to zero when the disconnect clutch is released
to disconnect the engine 14 from the motor 12. In mode 5, the
vehicle is preparing to transfer from the engine 14 as a source of
torque to the motor 12 as a source of torque. In mode 6, the engine
speed and motor speed are matched to within 5 rpm. Motor torque 36
and engine torque 38 remain relatively constant through modes 4 and
5. However, during mode 6 the source of torque is transferred from
the engine 14 to the motor 12. At the end of mode 6, the engine
speed begins to be reduced until the engine 14 stops.
[0027] Referring to FIG. 3, an alternative embodiment having two
variations is shown. The alternative embodiment of the modular
hybrid transmission (MHT) system 40 includes an electric traction
motor 42, a combustion engine 44, and a transmission gear box 46. A
hybrid rocker one way clutch 50 is operatively connected between
the engine 44 and the motor 42 that is adapted to connect and
disconnect the engine 44 from the motor 42. The hybrid rocker one
way clutch 50 is bi-directionally rotatable and is lockable in one
rotational direction by shifting the rocker, as is known in the
art. A damper 52 may also be provided between the hybrid rocker one
way clutch 50 and the engine 44.
[0028] In one variation, a one way clutch (OWC) 54 is connected in
parallel with the hybrid rocker one way clutch 50. Alternatively, a
second hybrid rocker one way clutch could be incorporated in place
of the OWC 54. One advantage of using a hybrid rocker one way
clutch 50 instead of the OWC 54 is that there is less parasitic
power loss than with a friction clutch type of OWC and can improve
fuel economy. The hybrid rocker one way clutch 54 includes a coil
(not shown) that requires energy to shift the rocker and may be
more expensive than a conventional OWC. However the hybrid rocker
one way clutch 54 is expected to improve performance in terms of
improved noise vibration and harshness. The hybrid rocker one way
clutches 50 and 54 do not require additional hydraulic control and
do not include friction clutch elements.
[0029] A starter motor 58 may be provided for starting the engine
44 in the embodiment shown in FIG. 4. It should be understood that
other starter arrangements may be provided that may benefit from
the concepts disclosed.
[0030] A launch clutch 60 is provided between the motor 42 and the
transmission gearbox 46. The launch clutch 60 provides torque to
the transmission gear box 46 from either or both of the motor 42 or
engine 44. In the embodiment of FIG. 3, no torque converter is
included in the gearbox. A torque converter could be included in
the combination and used in place of the launch clutch 60.
[0031] While exemplary embodiments are described above, it is not
intended that these embodiments describe all possible forms of the
disclosed apparatus and method. 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 disclosure as claimed. The
features of various implementing embodiments may be combined to
form further embodiments of the disclosed concepts.
* * * * *