Title of Invention

A DUAL INPUT CLUTCH TRANSMISSION AND A METHOD OF REDUCING AN AXIAL SPACE WITHIN A DUAL INPUT CLUTCH TRANSMISSION

Abstract A dual-input clutch transmission is provided having a torque converter with a rotatable hub, the transmission comprising a transmission pump having internal fluid channels and a rotor set which is drivingly connected to the hub, and a dual-input clutch in fluid communication with the transmission pump through the fluid channels. The pump and torque converter are positioned along a common axis of rotation, the pump circumscribing the torque converter hub to reduce axial space. The dual-input clutch is mounted to the transmission pump housing for structural support. A method is also provided for reducing axial space within a dual-input clutch transmission having a torque converter, including providing an on-axis transmission pump with a housing and rotor set, providing a torque converter with a rotatable hub which is drivingly connected to the rotor set for powering of the transmission pump, and mounting the dual-input clutch to the pump housing for support.
Full Text GP-308898-PTT-DI.T
1
DUAL INPUT CLUTCH TRANSMISSION WITH TORQUE CONVERTER PUMP
DRIVE
TECHNICAL FIELD
[0001 ] The present invention relates to an apparatus and method for driving a
transmission hydraulic pump within a vehicle having a dual input clutch transmission
with a hydrodynamic torque converter.
BACKGROUND OF THE INVENTION
[0002] A hydrodynamic torque converter is a device used to amplify and transmit
torque within step-type or single-input clutch automatic transmissions, replacing the
conventional plate clutch or clutch pack often found in standard or manual transmissions.
Conventional torque converters are contained within a separate housing that is bolted to
the engine flexplate and positioned between the engine and the transmission, and
therefore the torque converter housing turns or rotates at engine speed whenever the
engine is running. A torque converter is comprised of a number of key structural
members that cooperate to enable the engine crankshaft to continue rotating while the
vehicle is stationary, for example while idling at a stop light or in heavy traffic. The key
structural members include a turbine, i.e. the driven member of the torque converter,
which is drivingly connected to the transmission gearbox, a stationary stator for
redirecting the flow of fluid within the torque converter as the fluid exits the turbine, and
a centrifugal pump and cover assembly, i.e. the driving member of the torque converter
which is directly connected to the torque converter housing.
[0003| In contrast to a single-input clutch automatic transmission employing a
hydrodynamic torque converter, a dual-input clutch transmission, also referred to as a
DCT transmission, employs odd and even gears which are disposed on separate, coaxial
rotatable input shafts. This divided gear arrangement allows each of two separate input
clutches, typically wet or fluid lubricated friction clutch packs, to be dedicated to a
respective subset of gears, thereby providing a smoother gear shifting event, which in
turn may increase fuel efficiency while reducing shift shock. However, in spite of its

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enhanced shift performance capabilities, DCT transmissions generally require a greater
amount of axial packaging space due to the greater relative size of the dual-input clutch
than is required by a single-input clutch using a conventional torque converter.
SUMMARY OF THE INVENTION
[0004] Accordingly, an apparatus is provided for driving a transmission hydraulic
pump within a vehicle having a dual input clutch transmission with a hydrodynamic
torque converter, while also reducing axial packaging space within the transmission. The
transmission includes a transmission pump having an internal fluid channel, wherein the
dual-input clutch assembly is in fluid communication with the transmission pump
through the fluid channel. The transmission also includes a torque converter having a
torque converter pump and a rotatablc hub which is directly connected to the torque
converter pump and drivingly connected to the transmission pump.
[0005] In one aspect of the invention, the transmission pump and the torque
converter are adjacently positioned along a common axis of rotation, and the pump is
contained within a housing that at least partially supports the torque converter on one side
and the dual-input clutch assembly on the other side.
[0006] In another aspect of the invention, the transmission pump is positioned
between the torque converter assembly and dual-input clutch assembly along a common
axis of rotation with the torque converter, the pump having a plurality of tangs which are
drivingly connected to the hub through one ormore mating hub slots.
[0007] In another aspect of the invention, the transmission pump is a fixed
displacement pump having a gerotor gear set configured to further reduce axial packaging
space.
[0008] In another aspect of the invention, the transmission pump is positioned
along an axis different from that of the torque converter and is drivingly connected to the
torque converter hub using a drive-chain and sprocket assembly.
[0009] In another aspect of the invention, a method is provided for reducing axial
space within a dual-input clutch transmission having a torque converter and a
transmission pump, the method locating the transmission pump directly behind the torque

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converter and mounting the dual-input clutch to the transmission pump for support of the
dual-input clutch.
[0010] In another aspect of the invention, the method includes driving the
transmission pump directly using a rotatable hub of the torque converter, wherein the
transmission pump and the torque converter are positioned along a common axis of
rotation.
[0011] The above features and advantages and other features and advantages of
the present invention are readily apparent from the following detailed description of the
best modes for carrying out the invention when taken in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIGURE 1 is a cross-sectional view of a portion of a dual input clutch
transmission having an on-axis transmission pump according to the invention;
[0013] FIGURE 2A is a schematic view of a portion of a dual-input clutch
transmission having an off-axis hydrodynamic transmission pump according to a second
embodiment of the invention; and
[0014] FIGURE 2B is a schematic view of an off-axis hydrodynamic
transmission pump from the perspective of line AA of Figure 2A.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Referring to the drawings wherein like reference numbers correspond to
like or similar components throughout the several figures, there is shown in Figure 1 a
cross-sectional view of a portion of a dual-input clutch transmission or DCT transmission
10. For simplicity, only one axial portion of the DCT transmission 10 is shown relative to
its primary centerlinc of rotation or axis 12. The DCT transmission 10 has a
hydrodynamic torque converter assembly or torque converter 18 disposed within an outer
bell housing 14. The bell housing 14 is cast, welded, or otherwise formed and is
operativcly attached to a similarly cast main transmission case 20. The DCT transmission

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10 further includes a hydraulic transmission pump or on-axis pump 24 which at least
partially circumscribes or wraps around the axis 12, with the term "on-axis" referring to
the positional relationship of the on-axis pump 24 relative to the axis 12.
[0016] Mounted adjacent to or to the rear of on-axis pump 24 is a dual-input
clutch assembly 26, which is disposed within a separate clutch housing 80. Clutch
housing 80 is operatively attached to and supported by a substantially rigid structural
support portion or back-hub extension 50 of the on-axis pump 24 to reduce the need for
additional structural support members for the clutch housing 80. Dual-input clutch
assembly 26 is comprised of a first and second input clutch 30A, 30B, respectively, both
preferably wet-plate style friction clutch packs in direct fluid communication with the on-
axis pump 24 through one or more internal fluid passages 54. The internal fluid passages
54 are preferably circular in cross-section in order to minimize fluid friction losses within
the fluid passages as fluid (not shown) is delivered or conducted to the dual-input clutch
assembly 26 for lubricating and cooling of the first and second clutches 30A, 30B.
[0017] Still referring to Figure 1, torque converter 18 is comprised of a torque
converter pump 58, turbine 46, stator 72, cover 42 with lug 40, and torque converter
clutch assembly 48. The turbine 46 is operatively attached within the DCT transmission
10 to a transmission gear box (not shown), preferably driven only when the DCT
transmission 10 is in gear. A rotatable torque converter hub 22 protrudes or extends
axially outward from the torque converter pump 58 and has a slot 32 disposed thereon.
Hub 22 is operatively attached to the torque converter pump 58 and to the cover 42, both
of which are drivingly connected to the engine (not shown). Therefore, the torque
converter pump 58 and cover 42 continuously receive torque from the engine while the
engine is running and so are driven or rotated at engine speed.
[0018] On-axis pump 24 preferably at least partially circumscribes or wraps
around and is centered on the rotatable hub 22 as previously described hercinabove,
thereby minimizing the required amount of axial packaging space between the torque
converter 18 and the dual-input clutch assembly 26 while also providing a rigid structure
that the torque converter 18 and dual-input clutch assembly 26 may attach to for support,
as shown in Figure 1. On-axis pump 24 includes a pump body 25 containing a rotor set

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70 having a drive member 75 and a driven member 71, and various valves (not shown)
which are configured and arranged to control the operation of the on-axis pump 24, as
well as a pump cover 27 for covering and protecting the various internal pump
components. The pump body 25 and pump cover 27 may be constructed using any
suitable combination of ferrous and/or non-ferrous materials, depending on the design
requirements, for example to support the varying externally applied loads or forces in
addition to the loads or forces generated internally within the on-axis pump 24.
[0019] The on-axis pump 24 and/or pump cover 27 preferably contain one or
more internal fluid channels 31, 37, respectively, for efficiently conducting or directing
oil or fluid through the on-axis pump 24 to the dual-input clutch assembly 26 while also
minimizing the need for additional external fluid connectors. Additionally, configuring
the on-axis pump 24 and/or pump cover 27 in this manner may facilitate a more rapid
gear shifting process due to the more direct and shortened distances the fluid must travel
from the torque converter 18 to the dual-input clutch assembly 26. The internal fluid
channels 31,37 may take the form of, for example, various die or sand-cast channels or
passages formed within the cast-iron pump body 25 and/or cast-iron pump cover 27, or
may be drilled and/or milled/machined therein. The internal fluid channels 31, 37 may
optionally contain or connect to hydraulic valves (not shown) for regulating or limiting of
pump pressure and/or fluid flow, and/or for regulating the fluid flow to the dual-input
clutch assembly 26, torque converter 18, and/or torque converter clutch assembly 48, or
other transmission components as needed.
[0020] The pump cover 27 is a substantially rigid, stationary member having a
back hub extension 50 that provides further structural support for the dual-input clutch
assembly 26, and is operatively attached to a stator shaft 60 operable for grounding of the
stator 72, the attachment preferably accomplished using a serrated press fit and/or one or
more lugs/bolts (not shown). Stator shaft 60 is preferably a hollow concentric shaft
located radially inward of the hub 22. As stated previously hereinabove, hub 22 has one
or more slots 32 which are operatively connected or attached to a mating tang or tangs 35
which are attached to or formed on the drive member 75 of the rotor set 70. In lieu of a
tang/slot drive mechanism, "flats" may alternately be employed on both the hub 22 and

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on the drive member 75. Those skilled in the art will also recognize various other drive
mechanisms that may be used in lieu of slots/tangs or flats for drivingly connecting the
hub 22 with the rotor set 70 in the scope of the invention, for example mating gear teeth
or other suitable drive mechanism.
[0021] In the interest of further reducing axial space requirements of DCT
transmission 10, the on-axis pump 24 is preferably a fixed displacement pump utilizing a
gerotor gear set, although various other pump styles and rotor sets 70 may be used within
the scope of the invention. For example, involute gears or other gear forms or profiles, or
vane pumps, whether fixed or variable displacement, and other common pump styles or
designs may be configured for use within the scope of the invention. The rotatable pump
body 25 and its internal rotor set 70 are preferably comprised of the same or like material,
either ferrous or non-ferrous, so as to provide similar coefficients of thermal expansion
between the body 25 and rotor set 70 and to thereby allow for tighter internal clearances,
thus reducing internal fluid leakage.
[0022] Turning to Figure 2A, a second embodiment is shown for use with an
alternate packaging architecture, in which the on-axis pump 24 of Figure 1 is replaced by
an off-axis pump 124 mounted away from or off of the axis 12. The off-axis pump 124 is
driveably connected to or driven by the rotatable torque converter hub 22, preferably by a
first gear or sprocket 92 having a plurality of radially-projecting gear teeth 90 which are
matable or engagable with the links 78 of a drive chain 88. As depicted in Figure 2A, the
off-axis pump 124 is positioned or spaced above or laterally away from the axis 12,
although those skilled in the art will recognize that a variety of other positions or
locations may be used as axially limited design and packaging requirements dictate.
[0023] Turning now to Figure 2B, which is a schematic side view taken from the
direction of arrow AA of Figure 2 A, rotatable torque converter hub 22 rotates in
synchronization with the engine crankshaft (not shown), as previously described
hcreinabove. The rotation of hub 22, represented by arrow 91 A, rotates or drives the first
sprocket 92 to which it is operatively attached, the motion or rotation of which is
represented by arrows 91B. Drive chain 88, which may also be a drive belt or other
suitable drive mechanism, is operatively and driveably connected with a second sprocket

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96, which is in turn operatively and driveably connected to the pump rotor set 170 of the
off-axis pump 124, preferably to a pair of drive tangs 173 attached to or formed with a
drive member 175 of the rotor set 170. Those skilled in the art will recognize the form of
drive member 175 and driven member 171 of pump rotor set 170 will vary depending on
the type and/or style of pump used, with drive member 175 and driven member 171
preferably comprising a gerotor gear set as shown in Figure 2B. Therefore, as the torque
converter hub 22 rotates at engine speed and drives or rotates first sprocket 92, the second
sprocket 96 (arrows 91C) is driven or rotated by the motion of first sprocket 92 through
drive chain 88, the motion of which is represented by arrows 9 ID. The rotational motion
of second sprocket 96 powers or drives the drive-member 175 of the rotor set 170 of off-
axis pump 124, thereby continuously powering the driven-member 171 of the off-axis
pump 124 so that a reliable source of pressurized fluid (not shown) may be conducted
throughout the transmission to be used as needed.
[0024] In this alternate embodiment, the off-axis pump 124 may be positioned at
an axially compact distance from the torque converter 18 and dual-input clutch assembly
26 (see Figure 1), but may therefore require additional external fluid connectors and/or
passages (not shown) to deliver pressurized fluid (not shown) for controlling the
operation of the off-axis pump 124. Also, a separate support arrangement may be
required to support the dual-input clutch assembly 26 (see Figure 1) in an axially compact
configuration. While a chain-and-sprockct drive mechanism as described hereinabove is
the preferred mechanism, those skilled in the art will recognize that other drive
mechanisms may be suitable with the off-axis pump 124 within the scope of the present
invention. For example, a separate pump shaft may be disposed within a hollow outer
torque converter turbine shaft to conserve axial space.
[0025] While the best modes for carrying out the invention have been described
in detail, those familiar with the art to which this invention relates will recognize various
alternative designs and embodiments for practicing the invention within the scope of the
appended claims.

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CLAIMS
1. A dual input clutch transmission comprising:
an on-axis transmission pump having an internal fluid channel;
a dual-input clutch in fluid communication with said on-axis transmission
pump through said fluid channel; and
a torque converter having a torque converter pump and a rotatable hub
which is operatively connected to said torque converter pump and drivingly connected to
said on-axis transmission pump; wherein said torque converter and said on-axis
transmission pump are adjacently positioned along a common axis of rotation.
2. The transmission of claim 1, wherein said on-axis transmission
pump is contained within a pump housing that at least partially supports said torque
converter on one side and said dual-input clutch on another side.
3. The transmission of claim 1, wherein said rotatable hub is at least
partially circumscribed by said pump to minimize the axial size of said transmission.
4. The transmission of claim 1, wherein said rotatable hub has at least
one slot disposed at one end, and wherein said rotor set has at least one tang that is
operatively connected to said at least one slot, said slot being configured to transmit
torque to said rotor set when said rotatable hub is rotating.
5. The transmission of claim 4, wherein said on-axis transmission
pump is a fixed displacement pump including a gerotor gear set.
6. A dual-input clutch transmission having a torque converter and a
transmission pump directly behind the torque converter, wherein said torque converter is
drivingly connected to said transmission pump for powering thereof.

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7. The transmission of claim 6, wherein said transmission pump and
said torque converter are positioned along a common axis of rotation.
8. The transmission of claim 7, including a dual input clutch
substantially supported by said transmission pump, wherein said transmission pump has
an internal fluid channel, and wherein said dual-input clutch is in fluid communication
with said transmission pump through said internal fluid channel.
9. The transmission of claim 6, wherein said transmission pump is a
selected from the group of gear pump and vane pump.
10. The transmission of claim 6, wherein said transmission pump is
positioned off of the axis of rotation of said torque converter, and said torque converter
pump is drivingly connected to said transmission pump.
11. The transmission of claim 10, wherein the driving connection of
said torque converter to said transmission pump is a sprocket and chain.
12. A method of reducing axial space within a dual-input clutch
transmission having a torque converter and transmission pump, the method including:
locating said transmission pump directly behind said torque converter; and
mounting said dual-input clutch to said transmission pump for support of
said dual-input clutch.
13. The method of claim 12, wherein the torque converter and
transmission pump are positioned along a common axis of rotation, the method further
including driving said transmission pump directly using a rotatable hub of said torque
converter.

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14. The method of claim 12, further including configuring said on-axis
transmission pump with a plurality of internal fluid passages for fluid communication of
said on-axis transmission pump with said dual-input clutch.
15. The method of claim 12, wherein said on-axis transmission pump
is a fixed displacement pump having a gerotor gear set.
16. The method of claim 12, wherein said transmission pump is
selected from the group of gear pump and vane pump.
Dated this 10th day of AUGUST 2007

A dual-input clutch transmission is provided having a torque converter
with a rotatable hub, the transmission comprising a transmission pump having internal
fluid channels and a rotor set which is drivingly connected to the hub, and a dual-input
clutch in fluid communication with the transmission pump through the fluid channels.
The pump and torque converter are positioned along a common axis of rotation, the pump
circumscribing the torque converter hub to reduce axial space. The dual-input clutch is
mounted to the transmission pump housing for structural support. A method is also
provided for reducing axial space within a dual-input clutch transmission having a torque
converter, including providing an on-axis transmission pump with a housing and rotor
set, providing a torque converter with a rotatable hub which is drivingly connected to the
rotor set for powering of the transmission pump, and mounting the dual-input clutch to
the pump housing for support.

Documents:

01105-kol-2007-abstract.pdf

01105-kol-2007-assignment.pdf

01105-kol-2007-claims.pdf

01105-kol-2007-correspondence others 1.1.pdf

01105-kol-2007-correspondence others 1.2.pdf

01105-kol-2007-correspondence others 1.3.pdf

01105-kol-2007-correspondence others.pdf

01105-kol-2007-description complete.pdf

01105-kol-2007-drawings.pdf

01105-kol-2007-form 1.pdf

01105-kol-2007-form 18.pdf

01105-kol-2007-form 2.pdf

01105-kol-2007-form 3.pdf

01105-kol-2007-form 5.pdf

01105-kol-2007-priority document.pdf

1105-KOL-2007-ABSTRACT 1.1.pdf

1105-KOL-2007-ABSTRACT.pdf

1105-KOL-2007-AMANDED CLAIMS 1.1.pdf

1105-KOL-2007-AMANDED CLAIMS.pdf

1105-KOL-2007-ASSIGNMENT 1.1.pdf

1105-KOL-2007-CORRESPONDENCE 1.1.pdf

1105-KOL-2007-CORRESPONDENCE OTHERS 1.4.pdf

1105-KOL-2007-CORRESPONDENCE.pdf

1105-KOL-2007-DESCRIPTION (COMPLETE) 1.1.pdf

1105-KOL-2007-DESCRIPTION (COMPLETE).pdf

1105-KOL-2007-DRAWINGS 1.1.pdf

1105-KOL-2007-DRAWINGS.pdf

1105-KOL-2007-EXAMINATION REPORT REPLY RECIEVED.pdf

1105-KOL-2007-FORM 1-1.1.pdf

1105-KOL-2007-FORM 1.pdf

1105-KOL-2007-FORM 2-1.1.pdf

1105-KOL-2007-FORM 2.pdf

1105-KOL-2007-FORM 3.pdf

1105-KOL-2007-OTHERS 1.2.pdf

1105-KOL-2007-OTHERS-1.1.pdf

1105-KOL-2007-OTHERS.pdf

1105-KOL-2007-PA.pdf

1105-KOL-2007-PETITION UNDER RULE 137.pdf


Patent Number 248645
Indian Patent Application Number 1105/KOL/2007
PG Journal Number 31/2011
Publication Date 05-Aug-2011
Grant Date 01-Aug-2011
Date of Filing 10-Aug-2007
Name of Patentee GM GLOBAL TECHNOLOGY OPERATIONS, INC.
Applicant Address 300 GM RENAISSANCE CENTER, DETROIT, MICHIGAN
Inventors:
# Inventor's Name Inventor's Address
1 JOHN C. SCHULTZ 6817 HEATHERIDGE DRIVE, SALINE, MICHIGAN 48176
PCT International Classification Number F16H3/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 11/558064 2006-11-09 U.S.A.