U.S. patent application number 12/935548 was filed with the patent office on 2011-02-03 for gear arrangements for 7-speed dual clutch transmission.
This patent application is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS, INC.. Invention is credited to Axel Geiberger, Mikael B. Mohlin, Mathias Remmler, Markus Rockenbach.
Application Number | 20110023638 12/935548 |
Document ID | / |
Family ID | 40671915 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110023638 |
Kind Code |
A1 |
Mohlin; Mikael B. ; et
al. |
February 3, 2011 |
GEAR ARRANGEMENTS FOR 7-SPEED DUAL CLUTCH TRANSMISSION
Abstract
Double-clutch transmission (DCT) includes, but is not limited to
two input shafts that are connected to two clutch discs
respectively. The DCT further includes, but is not limited to
gearwheels on layshafts and the input shafts. The gearwheels
include, but are not limited to six gearwheel groups for providing
six gears respectively. Each of the gearwheel groups include, but
are not limited to a fixed gearwheel on one of the input shafts,
meshing with an idler gearwheel on one of the layshafts. A third
fixed gearwheel meshes with the third gear idler gearwheel and the
fifth gear idler gearwheel. Additionally, the DCT device further
includes, but is not limited to a seventh gearwheel group for
providing a seventh gear. The seventh gearwheel group includes, but
is not limited to a seventh fixed gearwheel, meshing with a seventh
gear idler gearwheel. The DCT further includes, but is not limited
to a reverse gear idler shaft and one reverse gearwheel on the
reverse gear idler shaft for providing a reverse gear.
Inventors: |
Mohlin; Mikael B.;
(Kungaelv, SE) ; Geiberger; Axel; (Mainz, DE)
; Remmler; Mathias; (Mauchenheim, DE) ;
Rockenbach; Markus; (Schweppenhausen, DE) |
Correspondence
Address: |
INGRASSIA FISHER & LORENZ, P.C. (GME)
7010 E. COCHISE ROAD
SCOTTSDALE
AZ
85253
US
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS,
INC.
Detroit
MI
|
Family ID: |
40671915 |
Appl. No.: |
12/935548 |
Filed: |
March 31, 2009 |
PCT Filed: |
March 31, 2009 |
PCT NO: |
PCT/EP09/02354 |
371 Date: |
September 29, 2010 |
Current U.S.
Class: |
74/330 |
Current CPC
Class: |
Y10T 74/19112 20150115;
F16H 3/093 20130101; F16H 3/006 20130101; F16H 2200/0056 20130101;
Y10T 74/19065 20150115; Y10T 74/1907 20150115; F16H 2003/0931
20130101; Y10T 74/19228 20150115; F16H 2003/0822 20130101; Y10T
74/19233 20150115; F16H 2200/0086 20130101; F16H 2003/0826
20130101 |
Class at
Publication: |
74/330 |
International
Class: |
F16H 3/08 20060101
F16H003/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2008 |
EP |
08006486.8 |
Mar 31, 2008 |
EP |
08006569.1 |
Mar 31, 2008 |
EP |
08006606.1 |
Mar 31, 2008 |
EP |
08006607.9 |
Mar 31, 2008 |
EP |
08006608.7 |
Mar 31, 2008 |
EP |
08006609.5 |
Mar 31, 2008 |
EP |
08006610.3 |
Mar 31, 2008 |
EP |
08006611.1 |
Mar 31, 2008 |
EP |
08006612.9 |
Mar 31, 2008 |
EP |
08006613.7 |
Mar 31, 2008 |
EP |
08006614.5 |
Mar 31, 2008 |
EP |
08006615.2 |
Mar 31, 2008 |
EP |
08006616.7 |
Mar 31, 2008 |
EP |
08006617.8 |
Mar 31, 2008 |
EP |
08006618.6 |
Mar 31, 2008 |
EP |
08006619.4 |
Mar 31, 2008 |
EP |
08006620.2 |
Mar 31, 2008 |
EP |
08006621.0 |
Mar 31, 2008 |
EP |
08006622.8 |
Mar 31, 2008 |
EP |
08006623.6 |
Mar 31, 2008 |
EP |
08006624.4 |
Mar 31, 2008 |
EP |
08006625.1 |
Mar 31, 2008 |
EP |
08006626.9 |
Mar 31, 2008 |
EP |
08006627.7 |
Mar 31, 2008 |
EP |
08006628.5 |
Mar 31, 2008 |
EP |
08006629.3 |
Mar 31, 2008 |
EP |
08006630.1 |
Mar 31, 2008 |
EP |
08006631.9 |
Mar 31, 2008 |
EP |
08006632.7 |
Mar 31, 2008 |
EP |
08006633.5 |
Mar 31, 2008 |
EP |
08006634.3 |
Mar 31, 2008 |
EP |
08006635.0 |
Mar 31, 2008 |
EP |
08006636.8 |
Mar 31, 2008 |
EP |
08006637.6 |
Mar 31, 2008 |
EP |
08006638.4 |
Mar 31, 2008 |
EP |
08006639.2 |
Mar 31, 2008 |
EP |
08006640.0 |
Mar 31, 2008 |
EP |
08006641.8 |
Mar 31, 2008 |
EP |
08006642.6 |
Mar 31, 2008 |
EP |
08006643.4 |
Mar 31, 2008 |
EP |
08006644.2 |
Mar 31, 2008 |
EP |
08006645.9 |
Mar 31, 2008 |
EP |
08006646.7 |
Mar 31, 2008 |
EP |
08006647.5 |
Mar 31, 2008 |
EP |
08006648.3 |
Mar 31, 2008 |
EP |
08006649.1 |
Claims
1. A double-clutch transmission, comprising: an inner input shaft
and an outer input shaft, at least a portion of the inner input
shaft surrounded by the outer input shaft; a first clutch connected
to the inner input shaft and a second clutch connected to the outer
input shaft; a first layshaft and a second layshaft radially spaced
apart from the inner input shaft and the outer input shaft and
arranged in parallel to the inner input shaft and the outer input
shaft, gearwheels arranged on the first layshaft, on the second
layshaft, on the inner input shaft, and on the outer input shaft,
the gearwheels comprising a first gearwheel group, a second
gearwheel group, a third gearwheel group, a fourth gearwheel group,
a fifth gearwheel group, and a sixth gearwheel group, which are
adapted to provide six gears, the first gearwheel group comprising
a first fixed gearwheel on the inner input shaft, meshing with a
first gear idler gearwheel on one of the first layshaft or the
second layshaft, the third gearwheel group comprising a third fixed
gearwheel on the inner input shaft, meshing with a third gear idler
gearwheel on one of the first layshaft or the second layshaft, the
fifth gearwheel group comprising a fifth fixed gearwheel on the
inner input shaft, meshing with a fifth gear idler gearwheel on one
of the first layshaft or the second layshaft, the second gearwheel
group comprising a second fixed gearwheel on the outer input
shafts, meshing with a second gear idler gearwheel on one of the
first layshaft or the second layshaft, the fourth gearwheel group
comprising a fourth fixed gearwheel on the outer input shafts,
meshing with a fourth gear idler gearwheel on one of the first
layshaft or the second layshaft, the sixth gearwheel group
comprising a sixth fixed gearwheel on the outer input shafts,
meshing with a sixth gear idler gearwheel on one of the first
layshaft or the second layshaft, and each gearwheel group
comprising a coupling device arranged on one of the first layshaft
or the second lay shaft to selectively engage one of the first
idler gearwheel, the second idler gearwheel, the third idler
gearwheel, the fourth idler gear wheel, the fifth idler gearwheel,
or sixth idler gearwheel, which are adapted to select one of the
six gears, and the third fixed gearwheel further meshing with the
fifth gear idler gearwheel, a seventh gearwheel group adapted to
provide a seventh gear, the seventh gearwheel group comprising a
seventh fixed gearwheel on the inner input shaft, meshing with a
seventh gear idler gearwheel on one of the first layshaft or the
second layshaft, the seventh gearwheel group further comprises a
coupling device arranged on one of the first layshaft or the second
layshaft to selectively engage the seventh gear idler gearwheel and
provide the seventh gear; and a reverse gear idler shaft and at
least one reverse gearwheel mounted on the reverse gear idler shaft
adapted to provide a reverse gear.
2. The double-clutch transmission of claim 1, wherein the first
forward gear and the reverse gear are provided by different input
shafts.
3. The double-clutch transmission according to claims, wherein the
at least one reverse gearwheel comprises a first reverse gearwheel
and a second reverse gearwheel that mesh with two gearwheels of the
seven gearwheel groups, respectively.
4. The double-clutch transmission of claim 3, wherein the first
reverse gearwheel meshes with the second fixed gearwheel, while the
second reverse gearwheel meshes with a reverse gear idler
wheel.
5. The double-clutch transmission according to claim 1, further
comprising: a park-lock gearwheel fixed onto one of the first
layshaft of the second layshaft and adapted to provide a
park-lock.
6. The double-clutch transmission according to claim 1, wherein at
least two of the first gear idler gearwheel, the second gear idler
gearwheel, the third gear idler gearwheel and the fourth gear idler
gearwheel are mounted on the same layshaft.
7. The double-clutch transmission according to claim 1, wherein at
least two of the fifth gear idler gearwheel, the sixth gear idler
gearwheel and the seventh gear idler gearwheel are mounted on the
same layshaft.
8. The double-clutch transmission according to claim 7, wherein the
fifth gear idler gearwheel, the sixth gear idler gearwheel and the
seventh gear idler gearwheel are mounted on the second layshaft,
which is lower then the first layshaft.
9. The double-clutch transmission according to claim 1, wherein the
coupling device comprises a double-sided coupling device for
engaging a gearwheel on a side of the coupling device to a shaft
that carries the coupling device.
10. The double-clutch transmission according to claim 1 further
comprising bearings adapted to support the first layshaft and the
second layshaft, at least one of the bearings provided next to one
of the first gear idler gearwheel or the second gear idler
gearwheel.
11. A gearbox, comprising: a double-clutch transmission,
comprising: an inner input shaft and an outer input shaft, at least
a portion of the inner input shaft surrounded by the outer input
shaft; a first clutch connected to the inner input shaft and a
second clutch connected to the outer input shaft; a first layshaft
and a second layshaft radially spaced apart from the inner input
shaft and the outer input shaft and arranged in parallel to the
inner input shaft and the outer input shaft, gearwheels arranged on
the first layshaft, on the second layshaft, on the inner input
shaft, and on the outer input shaft, the gearwheels comprising a
first gearwheel group, a second gearwheel group, a third gearwheel
group, a fourth gearwheel group, a fifth gearwheel group, and a
sixth gearwheel group, which are adapted to provide six gears, the
first gearwheel group comprising a first fixed gearwheel on the
inner input shaft, meshing with a first gear idler gearwheel on one
of the first layshaft or the second layshaft, the third gearwheel
group comprising a third fixed gearwheel on the inner input shaft,
meshing with a third gear idler gearwheel on one of the first
layshaft or the second layshaft, the fifth gearwheel group
comprising a fifth fixed gearwheel on the inner input shaft,
meshing with a fifth gear idler gearwheel on one of the first
layshaft or the second layshaft, the second gearwheel group
comprising a second fixed gearwheel on the outer input shafts,
meshing with a second gear idler gearwheel on one of the first
layshaft or the second layshaft, the fourth gearwheel group
comprising a fourth fixed gearwheel on the outer input shafts,
meshing with a fourth gear idler gearwheel on one of the first
layshaft or the second layshaft, the sixth gearwheel group
comprising a sixth fixed gearwheel on the outer input shafts,
meshing with a sixth gear idler gearwheel on one of the first
layshaft or the second layshaft, and each gearwheel group
comprising a coupling device arranged on one of the first layshaft
or the second lay shaft to selectively engage one of the first
idler gearwheel, the second idler gearwheel, the third idler
gearwheel, the fourth idler gear wheel, the fifth idler gearwheel,
or sixth idler gearwheel, which are adapted to select one of the
six gears, and the third fixed gearwheel further meshing with the
fifth gear idler gearwheel, a seventh gearwheel group adapted to
provide a seventh gear, the seventh gearwheel group comprising a
seventh fixed gearwheel on the inner input shaft, meshing with a
seventh gear idler gearwheel on one of the first layshaft or the
second layshaft, the seventh gearwheel group further comprises a
coupling device arranged on one of the first layshaft or the second
layshaft to selectively engage the seventh gear idler gearwheel and
provide the seventh gear; a reverse gear idler shaft and at least
one reverse gearwheel mounted on the reverse gear idler shaft
adapted to provide a reverse gear; and an output gearwheel that
meshes with pinions on the first layshaft and second layshaft,
respectively, for providing an output torque.
12. A power train device, comprising: a double-clutch transmission,
comprising: an inner input shaft and an outer input shaft, at least
a portion of the inner input shaft surrounded by the outer input
shaft; a first clutch connected to the inner input shaft and a
second clutch connected to the outer input shaft; a first layshaft
and a second layshaft radially spaced apart from the inner input
shaft and the outer input shaft and arranged in parallel to the
inner input shaft and the outer input shaft, gearwheels arranged on
the first layshaft, on the second layshaft, on the inner input
shaft, and on the outer input shaft, the gearwheels comprising a
first gearwheel group, a second gearwheel group, a third gearwheel
group, a fourth gearwheel group, a fifth gearwheel group, and a
sixth gearwheel group, which are adapted to provide six gears, the
first gearwheel group comprising a first fixed gearwheel on the
inner input shaft, meshing with a first gear idler gearwheel on one
of the first layshaft or the second layshaft, the third gearwheel
group comprising a third fixed gearwheel on the inner input shaft,
meshing with a third gear idler gearwheel on one of the first
layshaft or the second layshaft, the fifth gearwheel group
comprising a fifth fixed gearwheel on the inner input shaft,
meshing with a fifth gear idler gearwheel on one of the first
layshaft or the second layshaft, the second gearwheel group
comprising a second fixed gearwheel on the outer input shafts,
meshing with a second gear idler gearwheel on one of the first
layshaft or the second layshaft, the fourth gearwheel group
comprising a fourth fixed gearwheel on the outer input shafts,
meshing with a fourth gear idler gearwheel on one of the first
layshaft or the second layshaft, the sixth gearwheel group
comprising a sixth fixed gearwheel on the outer input shafts,
meshing with a sixth gear idler gearwheel on one of the first
layshaft or the second layshaft, and each gearwheel group
comprising a coupling device arranged on one of the first layshaft
or the second lay shaft to selectively engage one of the first
idler gearwheel, the second idler gearwheel, the third idler
gearwheel, the fourth idler gear wheel, the fifth idler gearwheel,
or sixth idler gearwheel, which are adapted to select one of the
six gears, and the third fixed gearwheel further meshing with the
fifth gear idler gearwheel, a seventh gearwheel group adapted to
provide a seventh gear, the seventh gearwheel group comprising a
seventh fixed gearwheel on the inner input shaft, meshing with a
seventh gear idler gearwheel on one of the first layshaft or the
second layshaft, the seventh gearwheel group further comprises a
coupling device arranged on one of the first layshaft or the second
layshaft to selectively engage the seventh gear idler gearwheel and
provide the seventh gear; a reverse gear idler shaft and at least
one reverse gearwheel mounted on the reverse gear idler shaft
adapted to provide a reverse gear; an output gearwheel that meshes
with pinions on the first layshaft and second layshaft,
respectively, for providing an output torque; and at least one
power source adapted to generate a driving torque.
13. The power train device of claim 12, wherein the power source
comprises a combustion engine.
14. The power train device of claim 12, wherein the power source
comprises an electric motor.
15. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National-Stage entry under 35
U.S.C. .sctn.371 based on International Application No.
PCT/EP2009/002354, filed Mar. 31, 2009, which was published under
PCT Article 21(2) and which claims priority to European Application
No. 08006645.9, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006638.4, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006639.2, filed Mar.
31, 2008, and which claims priority to European Application No.
08006640.0, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006641.8, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006642.6, filed Mar.
31, 2008, and which claims priority to European Application No.
08006635.0, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006643.4, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006644.2, filed Mar.
31, 2008, and which claims priority to European Application No.
08006486.8, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006606.1, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006607.9, filed Mar.
31, 2008, and which claims priority to European Application No.
08006608.7, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006646.7, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006616.7, filed Mar.
31, 2008, and which claims priority to European Application No.
08006617.8, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006609.5, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006610.3, filed Mar.
31, 2008, and which claims priority to European Application No.
08006611.1, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006612.9, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006621.0, filed Mar.
31, 2008, and which claims priority to European Application No.
08006622.8, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006623.6, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006624.4, filed Mar.
31, 2008, and which claims priority to European Application No.
08006569.1, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006637.6, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006615.2, filed Mar.
31, 2008, and which claims priority to European Application No.
08006636.8, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006625.1, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006626.9, filed Mar.
31, 2008, and which claims priority to European Application No.
08006627.7, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006628.5, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006629.3, filed Mar.
31, 2008, and which claims priority to European Application No.
08006630.1, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006631.9, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006619.4, filed Mar.
31, 2008, and which claims priority to European Application No.
08006620.2, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006618.6, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006614.5, filed Mar.
31, 2008, and which claims priority to European Application No.
08006613.7, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006634.3, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006633.5, filed Mar.
31, 2008, and which claims priority to European Application No.
08006632.7, filed Mar. 31, 2008, and which claims priority to
European Application No. 08006649.1, filed Mar. 31, 2008, and which
claims priority to European Application No. 08006648.3, filed Mar.
31, 2008, and which claims priority to European Application No.
08006647.5, filed Mar. 31, 2008, which are all hereby incorporated
in their entirety by reference.
TECHNICAL FIELD
[0002] The present application relates to a double-clutch
transmission for vehicles.
BACKGROUND
[0003] A double-clutch transmission (DCT) comprises two input
shafts that are connected to and actuated by two clutches
separately. The two clutches are often combined into a single
device that permits actuating any of the two clutches at a time.
The two clutches are connected to two input shafts of the DCT
separately for providing driving torques.
[0004] U.S. Pat. No. 7,246,534 B2 discloses a six-gear double
clutch transmission. The six-gear double clutch transmission has
not yet been widely used in cars for street driving. Problems that
hinder the application of DCT for street driving comprise of
providing a compact, reliable and fuel-efficient DCT. Therefore,
there exists a need for providing such a DCT that is also
affordable by consumers.
SUMMARY
[0005] The application provides a double-clutch transmission with
an inner input shaft and an outer input shaft. The inner shaft can
be hollow or solid. A portion of the inner input shaft is
surrounded by the outer input shaft in a radial direction. The
radial direction of a shaft indicates a direction pointing away
from a central axis of the shaft following a radius of the
shaft.
[0006] There is provided a first clutch and a second clutch that
are non-rotatably connected to the inner input shaft and to the
outer input shaft respectively. For example, the first clutch is
fixed to the inner input shaft and the second clutch is fixed to
the outer input shaft. Alternatively, the non-rotatable connection
can be provided by a universal joint.
[0007] The transmission further comprises a first layshaft, a
second layshaft radially spaced apart from the input shafts and
arranged in parallel to the input shafts.
[0008] At least one of the layshafts comprises a fixed output
gearwheel for outputting a drive torque to a torque drain, such as
a differential gearbox of a vehicle. Examples of the vehicle
include a car or a motorcycle. Pinions of the DCT comb with an
output gearwheel respectively such that the output gearwheel
transmits torques from the pinions to the output shaft for driving
the vehicle.
[0009] Gearwheels are arranged on the first layshaft, on the second
layshaft, on the inner input shaft and on the outer input shaft.
The gearwheels comprise a first gearwheel group, a second gearwheel
group, a third gearwheel group, a fourth gearwheel group, a fifth
gearwheel group and a sixth gearwheel group for providing six
sequentially increasing gears. The sequentially increasing gears
describe an escalating order that members of the order follow each
other. Gear ratios of a car are typically arranged in a
sequentially decreasing manner from first gear to sixth gear. For
example, in a vehicle having a transmission, a first gear has the
gear ratio of approximately 2.97:1; a second gear has the gear
ratio of approximately 2.07:1; a third gear has the gear ratio of
approximately 1.43:1; a fourth gear has the gear ratio of
approximately 1.00:1; a fifth gear has the gear ratio of
approximately 0.84:1; and a sixth gear has the gear ratio of
approximately 0.56:1. The six gears provide an increasing order of
output speed of the transmission for driving the vehicle.
[0010] The first gearwheel group comprises a first fixed gearwheel
on the inner input shaft, meshing with a first gear idler gearwheel
on one of the layshafts. The third gearwheel group comprising a
third fixed gearwheel on the inner input shaft, meshing with a
third gear idler gearwheel on one of the layshafts. The fifth
gearwheel group comprises a fifth fixed gearwheel on the inner
input shaft, meshing with a fifth gear idler gearwheel on one of
the layshafts. The second gearwheel group comprises a second fixed
gearwheel on the outer input shafts, meshing with a second gear
idler gearwheel on one of the layshafts. The fourth gearwheel group
comprises a fourth fixed gearwheel on the outer input shafts,
meshing with a fourth gear idler gearwheel on one of the layshafts.
The sixth gearwheel group comprises a sixth fixed gearwheel on the
outer input shafts, meshing with a sixth gear idler gearwheel on
one of the layshafts. Each gearwheel group comprises a coupling
device that is arranged on one of the layshafts to selectively
engage one of the idler gearwheels for selecting one of the six
gears.
[0011] The third fixed gearwheel on the inner input shaft meshes
with the third gear idler gearwheel and the fifth gear idler
gearwheel.
[0012] Additionally, the double-clutch transmission device
comprises a seventh gearwheel group for providing a seventh gear,
the seventh gearwheel group comprising a seventh fixed gearwheel on
the inner input shaft, meshing with a seventh gear idler gearwheel
on one of the layshafts. The seventh gearwheel group further
comprises a coupling device which is arranged on one of the
layshafts to selectively engage one of the idler gearwheels for
selecting the seventh gear. The double-clutch transmission device
further comprises a reverse gear idler shaft and at least one
reverse gearwheel mounted on the reverse gear idler shaft for
providing a reverse gear.
[0013] The double-clutch transmission provides seven forward gears
through the double-clutch. The double-clutch enables gear switching
between odd and even ratios to be swift and efficient because the
gearwheels for the odd gear and even gear are distributed to
different clutches respectively. A double-meshing is provided by
the third fixed gearwheel on the inner input shaft meshing with the
third gear idler gearwheel and the fifth gear idler gearwheel. The
double-meshing makes the double-clutch transmission to be compact,
light-weight at low cost because one fixed gearwheel is avoided on
one of the input shafts.
[0014] In the application, different input shafts may provide the
first forward gear and the reverse gear respectively. The DCT put
the first forward gear and the reverse gear on two different input
shafts. A double-clutch of the DCT enables that the switching
between the two input shafts can be achieved quickly. As a result,
a driving scheme that the DCT engages the two input shafts
alternatively can drive the vehicle back & forth rapidly. This
scheme is useful for moving the vehicle out of a muddy puddle
because the vehicle can simply be driven back & forth to get
out the puddle. Less loss of momentum of the gearwheels and the
layshafts of the DCT can be achieved.
[0015] In the application, the at least one reverse gearwheel may
comprise a first reverse gearwheel and a second reverse gearwheel
that mesh with two of the gearwheels respectively. The
double-clutch transmission further provides a reverse gear that
enables the vehicle to reverse. The reverse gear makes the vehicle
more maneuverable. The two reverse gearwheels enable the DCT to
eliminate a pinion only for the use of reverse gear. The absence of
the pinion reduces the weight and cost of the DCT.
[0016] In the application, the first reverse gearwheel may mesh
with the second fixed gearwheel, while the second reverse gearwheel
may mesh with a reverse gear idler wheel. Both the first reverse
gearwheel and the second reverse gearwheel share the same
rotational axis with the reverse gear idler shaft, which is
coaxial. In fact, a gearwheel is typically mounted to its
supporting shaft coaxially, unless otherwise stated. The fact that
a gearwheel and its supporting shaft having the same rotational
axis ensures uniform gear meshing of the gearwheel with its
neighboring gearwheel on a parallel shaft.
[0017] The double-clutch transmission can further comprise a
park-lock gearwheel that is fixed onto one of the layshafts for
providing a park-lock. The layshaft with the park-lock comprises a
final drive pinion for locking a differential of the DCT. The
differential comprises the output gearwheel on the output shaft.
The park-lock enables the vehicle to park at a place in a secure
manner, even on a slope. The park-lock is easy to implement and
beneficial for vehicle and passengers' safety.
[0018] In the application, at least two of the first gear idler
gearwheel, the second gear idler gearwheel, the third gear idler
gearwheel and the fourth gear idler gearwheel may be mounted on the
same layshaft. Gearwheels of lower gears (e.g. 1st, 2nd, 3rd &
4th gears) are desired to be installed on the same shaft because
only one of the layshafts 40, 50 needs to be made strong for
carrying heavy torque.
[0019] In the application, at least two of the fifth gear idler
gearwheel, the sixth gear idler gearwheel and the seventh gear
idler gearwheel are mounted on the same layshaft. More gearwheels
of high gears mounted on the same shaft provide further opportunity
for installing gearwheels of low gears on another shaft. The other
shaft can thus be made short for carrying less number of
gearwheels.
[0020] In the application, the fifth gear idler gearwheel, the
sixth gear idler gearwheel and the seventh gear idler gearwheel may
be mounted on the lower layshaft. Gearwheels of higher gears (e.g.,
5th, 6.sup.th, & 7th gears) are desired to be installed on the
same shaft because the shaft can be made slim for carrying less
torque. Consequently, the DCT can be made with low cost and
lightweight. Three gearwheels of high gears mounted on the same
layshaft greatly help to reduce weight of the layshaft. The DCT
with the layshaft can also be made lighter. Bearings for supporting
the layshaft of high gears become less demanding.
[0021] In the application, the coupling device may comprise a
double-sided coupling device for engaging a gearwheel on the left
side or right side of the coupling device to a shaft that carries
the coupling device.
[0022] In the application, there may be further provided bearings
for supporting the layshafts, at least one of the bearings being
provided next to one of the first gear idler gearwheel and the
second gear idler gearwheel. Bearings that support a shaft are more
advantageously provided next to gearwheels of low gears. The
supporting shaft can be made slim and have less deflection when the
bearings are next to the gearwheels of low gears.
[0023] In the application, the DCT may further comprise an output
gearwheel that meshes with pinions on the layshafts for providing
an output torque. The output gearwheel receives driving torques
from pinions and offer a single output to the exterior of the
double-clutch transmission. No multiple external connections that
are associated to the layshafts are required. Connection to the
double-clutch transmission is thus made simple.
[0024] In the application, there may be provided a power train
device with the gearbox. The power train device may comprise at
least one power source for generating a driving torque. The power
train device is alternatively known as power train.
[0025] In the application, the power source comprises a combustion
engine. The vehicle having the combustion engine and the
double-clutch transmission is easy to manufacture.
[0026] The combustion engine can consume less petrol for
environmental protection. Furthermore, a combustion engine for
other types of fuel can have even less polluting emission, such as
hydrogen fuel.
[0027] In the application, the power source may comprise an
electric motor. Electric motor used in as hybrid car, or in an
electrical car enables reduction of pollution, as compared to
typical combustion using petrol. The electric motor can even
recuperate brake energy in a generator mode.
[0028] In the application, there may be provided a vehicle
comprising the power train device. The vehicle having the power
train device is efficient in energy usage by using the
double-clutch transmission.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The present invention will hereinafter be described in
conjunction with the following drawing figures, wherein like
numerals denote like elements, and
[0030] FIG. 1 illustrates a front view of an embodiment of a double
clutch transmission of the application;
[0031] FIG. 2 illustrates the path of torque flow of a first gear
transmission ratio;
[0032] FIG. 3 illustrates the path of torque flow of a second gear
transmission ratio;
[0033] FIG. 4 illustrates the path of torque flow of a third gear
transmission ratio;
[0034] FIG. 5 illustrates the path of torque flow of a fourth gear
transmission ratio;
[0035] FIG. 6 illustrates the path of torque flow of a fifth gear
transmission ratio;
[0036] FIG. 7 illustrates the path of torque flow of a sixth gear
transmission ratio;
[0037] FIG. 8 illustrates the path of torque flow of a seventh gear
transmission ratio;
[0038] FIG. 9 illustrates the path of torque flow of a reverse gear
transmission ratio;
[0039] FIG. 10 illustrates an assembly of a double-sided coupling
device with its neighboring gearwheels for engagement;
[0040] FIG. 11 illustrates an assembly of a single-sided coupling
device with its neighboring gearwheel for engagement;
[0041] FIG. 12 illustrates an assembly of an idler gearwheel that
is rotatably supported by a shaft on a bearing;
[0042] FIG. 13 illustrates an assembly of a fixed gearwheel that is
supported on a shaft;
[0043] FIG. 14 illustrates a cross-section through a crankshaft of
an internal combustion engine according to the embodiment of the
DCT; and
[0044] FIG. 15 illustrates an alternative front view of the
expanded side view of the double clutch transmission in FIG. 2.
DETAILED DESCRIPTION
[0045] The following detailed description is merely exemplary in
nature and is not intended to limit application and uses.
Furthermore, there is no intention to be bound by any theory
presented in the preceding background or summary or the following
detailed description. In the following description, details are
provided to describe the embodiment of the application. It shall be
apparent to one skilled in the art, however, that the embodiment
may be practiced without such details.
[0046] FIGS. 1-14 provide detailed description of an embodiment of
a double clutch transmission (DCT) of the application.
[0047] FIG. 1 illustrates a front view of an embodiment of a double
clutch transmission 1 of the application. The DCT 1 comprises a
relatively large output gearwheel 12, two input shafts 20, 22, two
pinions 41, 51 and a reverse gear idler shaft 38. The two input
shafts 20, 22 are a solid input shaft 20 (i.e. K1) and a hollow
input shaft 22 (i.e. K2). The solid input shaft 20 and the hollow
input shaft 22 share the same rotational axis and are non-rotatably
connected to two clutch discs 8, 10 of a double clutch 6
separately. The two pinions 41, 51 are the upper pinion 41 and the
lower pinion 51. The two pinions 41, 51 are fixed to an upper
layshaft 40 and a lower layshaft 50 at their rotational axes
respectively. The output gearwheel 12 is fixed to an output shaft
14 at its rotation axis. The two pinions 41, 51 mesh with the
output gearwheel 12 separately at different positions of the output
gearwheel 12.
[0048] The input shafts 20, 22, the upper layshaft 40, the lower
layshaft 50, the reverse gear idler shaft 38 and the output shaft
14 are parallel to each other at predetermined distances. The
distances are provided in radial directions of these shafts 20, 22,
40, 50, 38, 14 which are better seen in FIG. 2. Other gearwheels
are mounted on these shafts 20, 22, 40, 50, 38, 14 respectively and
mesh with each other according to predetermined manners. The
manners of these gearwheels' mounting and meshing are better seen
in some of the following figures.
[0049] FIG. 1 further shows a cutting plane A-A for illustrating an
expanded cross-section view through the DCT 1, which is shown in
FIGS. 2 to 9. The cutting plane A-A passes through the rotational
axes of the lower pinion 51, the output gearwheel 12, the input
shafts 20, 22, the upper pinion 41 and the reverse gear idler shaft
38. One of the goals of FIGS. 2 to 9 is to further illustrate
structure and torque flows of the DCT 1.
[0050] FIG. 2 illustrates the expanded view of the DCT 1 that shows
the manners of the gearwheels mounting, which corresponds to FIG.
1.
[0051] According to FIG. 2, the DCT 1 comprises the following
shafts, from top to bottom, the reverse gear idler shaft 38, the
upper layshaft 40, the solid input shaft 20, the hollow input shaft
22, the lower layshaft 50 and the output shaft 14. The solid input
shaft 20 is partially disposed inside the hollow input shaft 22,
while the solid input shaft 20 protrudes outside the hollow input
shaft 22 at its two ends. The hollow input shaft 22 is mounted onto
the solid input shaft 20 by a pair of solid shaft bearings 71 that
are disposed between the solid input shaft 20 and the hollow input
shaft 22 at two ends of the hollow input shaft 22. As a result, the
two input shafts 20, 22 are coupled together such that the solid
input shaft 20 is free to rotate inside the hollow input shaft 22.
The hollow input shaft 22 surrounds a right portion of the solid
input shaft 20, while a left portion of the solid input shaft 20 is
exposed outside the hollow input shaft 22. The assembly of the
input shafts 20, 22 is supported by a solid shaft bearing 71 at a
protruding end of the solid shaft 20 on the left and by a hollow
shaft bearing 72 on the right.
[0052] As shown in FIG. 2, a portion of the solid input shaft 20 is
surrounded by the outer input shaft 22 in a radial direction of the
input shafts 20, 22. There are three gearwheels 25, 27, 24 mounted
on the left exposed portion of the solid input shaft 20. These
gearwheels 25, 27, 24 are a fixed wheel third gear 25, a fixed
wheel seventh gear 27 and a fixed wheel first gear 24. The fixed
wheel third gear 25, the fixed wheel seventh gear 27 and the fixed
wheel first gear 24 are disposed on the exposed portion of the
solid shaft 20 from right to left sequentially. The fixed wheel
third gear 25 also serves as a fixed wheel fifth gear 26. On the
hollow input shaft 22, which is mounted on the right portion of the
solid input shaft 20, there is mounted with a fixed wheel second
gear 30, a fixed wheel fourth gear 32 and a fixed wheel fourth gear
31 from right to left. The fixed wheel second gear 30, the fixed
wheel fourth gear 32 and the fixed wheel fourth gear 31 are fixed
to the hollow input shaft 22 coaxially.
[0053] The lower layshaft 50 is provided below the solid input
shaft 20 and the hollow input shaft 22. There are a number of
gearwheels and coupling devices mounted on the lower layshaft 50,
which include, from right to the left, the lower pinion 51, an
idler second gear 61, a double-sided coupling device 83, an idler
fourth gear 63, an idler third gear 62, a double-sided coupling
device 82 and an idler first gear 60. One layshaft bearing 73 is
provided next to both the lower pinion 51 and the idler second gear
61. The other layshaft bearing 73 is provided next to the idler
first gear 60 at the left end of the lower layshaft 50. The lower
pinion 51 is fixed to the lower layshaft 50 at its rotational axis.
The idler second gear 61, the idler fourth gear 63, the idler third
gear 62 and the idler first gear 60 are mounted on the lower
layshaft 50 by bearings separately such that these gearwheels 61,
63, 62, 60 are idlers, being free to rotate around the lower
layshaft 50. In other words, gearwheels of low gears 60, 61, 62, 63
are provided on the same layshaft 50, while the two layshafts'
bearings 73 are next to the gearwheels of the lowest gears 60, 61.
The double-sided coupling device 83 is provided between the idler
second gear 61 and the idler fourth gear 63. The other double-sided
coupling device 82 is provided between the idler third gear 62 and
the idler first gear 60. Both the double-sided coupling devices 82,
83 are configured to move along the lower layshaft 50 such that
they can either engage a gearwheel on their left or right to the
lower layshaft 50 respectively. The idler second gear 61 meshes
with the fixed wheel second gear 30. The idler fourth gear 63
meshes with the fixed wheel fourth gear 31. The idler third gear 62
meshes with the fixed wheel third gear 25. The idler first gear 60
meshes with the fixed wheel first gear 24.
[0054] The upper layshaft 40 is provided above the input shafts 20,
22. There is provided gearwheels and coupling devices on the upper
layshaft 40, which includes, from right to the left, the upper
pinion 41, a reverse gear idler wheel 37, a double-sided coupling
device 80, an idler sixth gear 65, a park-lock gearwheel 39, an
idler fifth gear 64, a double-sided coupling device 81 and an idler
seventh gear 66. One layshaft bearing 73 is positioned next to and
between the upper pinion 41 and the reverse gear idler wheel 37.
Another layshaft bearing 73 is positioned at another end of the
upper layshaft 40, next to the idler seventh gear 66. The reverse
gear idler gear wheel 37, the idler sixth gear 65, the idler fifth
gear 64, the idler seventh gear 66 are mounted on the upper
layshaft 40 by bearings respectively such that these gearwheels 37,
65, 64, 66 are free to rotate around the upper layshaft 40. In
other words, gearwheels of high gears 64, 65, 66 are mounted on the
same shaft 40. The double-sided coupling device 80 is configured to
move along the upper layshaft 40 to engage or disengage either the
reverse gear idler wheel 37 or the idler sixth gear 65 to the upper
layshaft 40 at a time. The other double-sided coupling device 81 is
configured to move along the upper layshaft 40 to engage or
disengage any of the idler fifth gear 64 and the idler seventh gear
66 to the upper layshaft 40 at a time. The idler sixth gear 65
meshes with the fixed wheel sixth gear 32. The idler fifth gear 64
meshes with fixed wheel fifth gear 26. The idler seventh gear 66
meshes with the fixed wheel seventh gear 27.
[0055] In other words, there is only one double-meshing provided
between the two layshafts 40, 50. The double-meshing comprises the
idler fifth gear 64 that meshes with the idler third gear 62 via
the fixed wheel third gear 25. The fixed wheel third gear 25 also
serves as the fixed wheel fifth gear 26.
[0056] The reverse gear idler shaft 38 is provided further above
the upper layshaft 40. There is provided gearwheels on the reverse
gear idler shaft 38, which includes, from right to the left, a
first reverse gearwheel 35 and a second reverse gearwheel 36. Two
idler shaft bearings 74 are provided at two ends of the reverse
gear idler shaft 38 respectively. Both the first reverse gearwheel
35 and the second reverse gearwheel 36 are fixed on the reverse
gear idler shaft 38 coaxially. The first reverse gearwheel 35
meshes with the idler second gear 61 via an intermediate gearwheel,
which is the fixed wheel second gear 30. The second reverse
gearwheel 36 meshes with the reverse gear idler wheel 37.
[0057] The output shaft 14 is provided below the lower layshaft 50.
A pair of output shaft bearings 75 is provided at two opposite ends
of the output shaft 14 for supporting. The output gearwheel 12 is
fixed on the output shaft 14 coaxially. The output gearwheel 12
meshes with both the lower pinion 51 and the upper pinion 41.
[0058] In the present specification, the expressions "mesh" and
"comb" with respect to geared wheels or engaged gearwheels are
provided as synonyms. The solid input shaft 20 is alternatively
termed as an inner input shaft 20, while the hollow input shaft 22
is alternatively termed as an outer input shaft 22. The solid input
shaft 20 is alternatively replaced by a hollow shaft that is
disposed inside the hollow input shaft 22. The term "coupling
device" is alternatively termed as "shifting mechanism" for
engaging or disengaging gearwheels on a shaft. The double-clutch
transmission (DCT) is alternatively termed as double-clutch, double
clutch transmission or dual clutch transmission (DCT). Any on of
the input shafts 20, 22 can be held by more than two bearings for
better support.
[0059] The fixed wheel first gear 24 is also known as the first
fixed gearwheel 24. The fixed wheel third gear 25 is also known as
the third fixed gearwheel 25. The fixed wheel fifth gear 26 is also
known as the fifth fixed gearwheel 26. The fixed wheel seventh gear
27 is also known as the seventh fixed gearwheel 27. The fixed wheel
second gear 30 is also known the second fixed gearwheel 30. The
fixed wheel fourth gear 31 is also known as the fourth fixed
gearwheel 31. The fixed wheel sixth gear 32 is also known as the
sixth fixed gearwheel 32. The idler first gear 60 is also known as
the first gear idler gearwheel 60. The idler second gear 61 is also
known as the second gear idler gearwheel 61. The idler third gear
62 is also known as the third gear idler gearwheel 62. The idler
fourth gear 63 is also known as the fourth gear idler gearwheel 63.
The idler fifth gear 64 is also known as the fifth gear idler
gearwheel 64. The idler sixth gear 65 is also known as the sixth
gear idler gearwheel 65. The idler seventh gear 66 is also known as
the seventh gear idler gearwheel 66. The coupling devices are
alternatively known as synchronizers.
[0060] The application provides the DCT 1 that permits gear shift
operations with less loss of driving torque. This is because the
gear shift operations can be achieved by selectively connecting one
of the two clutch discs 8, 10 of the DCT 1. Therefore, an
associated additional main drive clutch can be avoided. The
selective connection between the two clutch discs 8, 10 also
enables the realization of an automatic transmission that can be
operated without interruptions in propulsive power. The propulsive
power comprises momentum derived from the rotating gearwheels and
shafts inside the DCT 1. Such a transmission is similar in design
to a mechanical manual transmission and it has correspondingly very
low friction losses. The double-clutch transmission 1 further
provides a parallel manual transmission that can be used for
transverse installation in a front-wheel drive vehicle.
[0061] The DCT 1 according to the application can be connected
similar to a known manual transmission, such as a parallel manual
transmission. In the know manual transmission, a drive shaft for
the front axle of a vehicle extends outward from its DCT case, and
parallel to the output shaft 14 of the main DCT 1. The arrangement
of the known manual transmission provides little space left for
actuation of the manual transmission and clutch, and also for an
optional electric motor. The optional electric motor can act as a
starter device for a combustion engine, as an energy recuperation
device for brake operation or as an additional drive means in
hybrid vehicles. Having such little space presents a number of
difficulties that are solved or at least alleviated by the
application. The application provides a double-clutch transmission
1 that has two clutches for connecting to an electrical motor and
the manual transmission in a compact manner.
[0062] The application provides a compact structure of a parallel
transmission. The application provides the parallel transmission
for a vehicle that includes two input shafts 20, 22, each of which
can be non-rotatably coupled via its own clutch to a shaft that is
powered by a drive engine. The DCT 1 of the application further
provides the output shaft 14 that is parallel to the input shafts
20, 22.
[0063] The double-clutch transmission 1 according to the
application is particularly well suited for transverse installation
in front-wheel drive vehicles, in which the front differential, for
example, is positioned below the pinions 41, 51. A short overall
length of the power train for transmitting the torques can be
achieved.
[0064] The application provides at least two relatively small
pinions 41, 51 on intermediately arranged layshafts 40, 50 which
combs with one relatively big output gearwheel 12 that in turn is
connected with the output shaft 14. This arrangement provides a
compact and lightweight DCT 1.
[0065] The application further allows a design in which the output
gearwheel 12 is integrated into a transmission differential device
without providing an intermediate output shaft of the DCT 1. This
allows a very dense packaging situation for the DCT 1.
[0066] It is further advantageous to provide fixed wheels for the
even gearwheels on one input shaft and fixed gearwheels for the odd
gears on another input shaft. This arrangement provides the
above-mentioned power-shift operation in a smooth and efficient
manner when gear shift is performed sequentially. This is because
the DCT 1 can alternatively engage one of the two clutch discs 8,
10. For example, the power-shift operation from the first gear to
the fourth gear causes the solid input shaft 20 and the hollow
input shaft 22 being engaged alternatively, which is energy
efficient and fast.
[0067] The single double-meshing of the idler third gear 62 and the
idler fifth gear 64 via the intermediate fixed wheel third gear 25
(i.e. fixed wheel fifth gear 26) provides efficient gear shifts
between the third and the fifth. No input shaft or clutch change is
required for the direct gear shift between the third gear and the
fifth gear. Since the fixed wheel third gear 25 is the same as the
fixed wheel fifth gear 26, no additional gearwheel is required for
providing each of the third and fifth gears. The solid input shaft
20 can thus be made shorter and one gearwheel is saved for reducing
cost and weight of the DCT 1.
[0068] Gearwheels 60, 61, 62, 63 of the low gears (i.e. 1st, 2nd,
3rd & 4th gears) are provided on the same lower layshaft 50,
which is advantageous. This is because the lower layshaft 50 has
lower rotational speed with larger size for higher torque, as
compared to that of the upper layshaft 40. This arrangement
eliminates the need of providing multiple layshafts with larger
sizes for carrying those heavy-load gearwheels 60, 61, 62, 63 of
the low gears separately. Therefore, the DCT 1 can be made light
with less cost.
[0069] Bearings 73 of the DCT 1 are mounted next to gearwheels 60,
61 of low gears and the pinions 41, 51. This arrangement provides
stronger mechanical support to the shafts 40, 50 for less shaft
deflection. Similarly, the bearings 74, 75 for the reverse gear
idler shaft 38 and the output shaft 14 are also close to the
gearwheels 12, 35, 36. As a result, the shafts 14, 38 can be
reduced in weight for lower cost.
[0070] It is also of advantage to drive the gearwheel groups of the
first gear and the reverse gear by different input shafts 20, 22 of
the DCT 1. This provides the ability to drive a vehicle change
between a slow forward and a slow backward without engaging and
disengaging the same group of gearwheels. Just by engaging and
disengaging the respective clutches 8, 10 of the two input shafts
20, 22, the DCT 1 enables the vehicle to move back and forth
quickly with little loss of the transmission power or gearwheels
momentum. This helps in many situations in which a wheel of a
vehicle is stuck in a hostile environment such as a snow hole or a
mud hole. The vehicle can then be swayed free just by switching
between the two clutch discs 8, 10 of the DCT 1.
[0071] A variant of the embodiment with one double-shared gearwheel
on one or both of the input shafts 20, 22 has the advantage of
providing a higher ratio-flexibility and of less dependency. It is
beneficial to provide the gearwheels of the first gear, of the
reverse gear and of the second gear close to the bearings for
supporting. The gearwheels of these gearwheels of low gears (e.g.
1st gear, 2nd gear, reverse gear, etc) undergo bigger forces than
those of the higher gears because the drive ratio is larger for the
lower gears and reverse gears. Therefore, their shafts 38, 50 must
take up higher driving forces. If those forces are taken up close
to the support points of the shafts 38, 50, excessive shafts'
bending will be reduced.
[0072] FIG. 2 illustrates the path of torque flow of a first gear
transmission ratio. In FIG. 2, an input torque of the first gear is
received from a crankshaft 2 of a combustion engine (not shown).
According to FIG. 2, the input torque of the first gear is received
by the solid input shaft 20 from the double-clutch 6 of the DCT 1.
A torque of the first gear is transmitted from the solid input
shaft 20, via the fixed wheel first gear 24, via the idler first
gear 60, via the double-sided coupling device 82, via the lower
layshaft 50, via the lower pinion 51, via the output gearwheel 12,
to the output shaft 14. The double-sided coupling device 82 is
engaged to the idler first gear 60 when transmitting the torque of
the first gear, which provides the first gear of the DCT 1. The
number of tooth engagements or engaged gear pairs for the torque
transfer of the first gear is two.
[0073] FIG. 3 illustrates the path of torque flow of a second gear
transmission ratio. In FIG. 3, an input torque of the second gear
is received from the crankshaft 2 of the combustion engine (not
shown). According to FIG. 3, the input torque of the second gear is
received by the hollow input shaft 22 from the double-clutch 6 of
the DCT 1. A torque of the second gear is transmitted from the
hollow input shaft 22, via the fixed wheel second gear 30, via the
idler second gear 61, via the double-sided coupling device 83, via
the lower layshaft 50, via the lower pinion 51, via the output
gearwheel 12, to the output shaft 14. The double-sided coupling
device 83 is engaged to the idler second gear 61 when transmitting
the torque of the second gear, which provides the second gear of
the DCT 1. The number of tooth engagements or engaged gear pairs
for the torque transfer of the second gear is two.
[0074] FIG. 4 illustrates the path of torque flow of a third gear
transmission ratio. In FIG. 4, an input torque of the third gear is
received from the crankshaft 2 of the combustion engine (not
shown). According to FIG. 4, the input torque of the third gear is
received by the solid input shaft 20 from the double-clutch of the
DCT 1. A torque of the third gear is transmitted from the solid
input shaft 20, via the fixed wheel third gear 25, via the idler
third gear 62, via the double-sided coupling device 82, via the
lower layshaft 50, via the lower pinion 51, via the output
gearwheel 12, to the output shaft 14. The double-sided coupling
device 82 is engaged to the idler third gear 62 when transmitting
the torque of the third gear, which provides the third gear of the
DCT 1. The number of tooth engagements or engaged gear pairs for
the torque transfer of the third gear is two.
[0075] FIG. 5 illustrates the path of torque flow of a fourth gear
transmission ratio. In FIG. 5, an input torque of the fourth gear
is received from the crankshaft 2 of the combustion engine (not
shown). According to FIG. 5, the input torque of the fourth gear is
received by the hollow input shaft 22 from the double-clutch 6 of
the DCT 1. A torque of the fourth gear is transmitted from the
hollow input shaft 22, via the fixed wheel fourth gear 31, via the
idler fourth gear 63, via the double-sided coupling device 83, via
the lower layshaft 50, via the lower pinion 51, via the output
gearwheel 12, to the output shaft 14. The double-sided coupling
device 83 is engaged to the idler fourth gear 63 when transmitting
the torque of the fourth gear, which provides the fourth gear of
the DCT 1. The number of tooth engagements or engaged gear pairs
for the torque transfer of the fourth gear is two.
[0076] FIG. 6 illustrates the path of torque flow of a fifth gear
transmission ratio. In FIG. 6, an input torque of the fifth gear is
received from the crankshaft 2 of a combustion engine (not shown).
According to FIG. 6, the input torque of the fifth gear is received
by the solid input shaft 20 from the double-clutch 6 of the DCT 1.
A torque of the fifth gear is transmitted from the solid input
shaft 20, via the fixed wheel fifth gear 26, via the idler fifth
gear 64, via the double-sided coupling device 81, via the upper
layshaft 40, via the upper pinion 41, via the output gearwheel 12,
to the output shaft 14. The double-sided coupling device 81 is
engaged to the idler fifth gear 64 when transmitting the torque of
the fifth gear, which provides the fifth gear of the DCT 1. The
number of tooth engagements or engaged gear pairs for the torque
transfer of the fifth gear is two.
[0077] FIG. 7 illustrates the path of torque flow of a sixth gear
transmission ratio. In FIG. 7, an input torque of the sixth gear is
received from the crankshaft 2 of a combustion engine (not shown).
According to FIG. 7, the input torque of the sixth gear is received
by the hollow input shaft 22 from the double-clutch 6 of the DCT 1.
A torque of the sixth gear is transmitted from the hollow input
shaft 22, via the fixed wheel sixth gear 32, via the idler sixth
gear 65, via the double-sided coupling device 80, via the upper
layshaft 40, via the upper pinion 41, via the output gearwheel 12,
to the output shaft 14. The double-sided coupling device 80 is
engaged to the idler sixth gear 65 when transmitting the torque of
the sixth gear, which provides the sixth gear of the DCT 1. The
number of tooth engagements or engaged gear pairs for the torque
transfer of the sixth gear is two.
[0078] FIG. 8 illustrates the path of torque flow of a seventh gear
transmission ratio. In FIG. 8, an input torque of the seventh gear
is received from the crankshaft 2 of a combustion engine (not
shown). According to FIG. 8, the input torque of the seventh gear
is received by the solid input shaft 20 from the double-clutch 6 of
the DCT 1. A torque of the seventh gear is transmitted from the
solid input shaft 20, via the fixed wheel seventh gear 27, via the
idler seventh gear 66, via the double-sided coupling device 81, via
the upper layshaft 40, via the upper pinion 41, via the output
gearwheel 12, to the output shaft 14. The double-sided coupling
device 81 is engaged to the idler seventh gear 66 when transmitting
the torque of the seventh gear, which provides the seventh gear of
the DCT 1. The number of tooth engagements or engaged gear pairs
for the torque transfer of the seventh gear is two.
[0079] FIG. 9 illustrates the path of torque flow of a reverse gear
transmission ratio. In FIG. 9, an input torque of the reverse gear
is received from the crankshaft 2 of a combustion engine (not
shown). According to FIG. 9, the input torque of the reverse gear
is received by the hollow input shaft 22 from the double-clutch 6
of the DCT 1. A torque of the reverse gear is transmitted from the
hollow input shaft 22, via the fixed wheel second gear 30, via the
first reverse gearwheel 35, via the reverse gear idler shaft 38,
via the second reverse gearwheel 36, via the reverse gear idler
wheel 37, via the double-sided coupling device 80, via the upper
layshaft 40, via the upper pinion 41, via the output gearwheel 12,
to the output shaft 14. The double-sided coupling device 80 is
engaged to the reverse gear idler wheel 37 when transmitting the
torque of the reverse gear, which provides the reverse gear of the
DCT 1. The number of tooth engagements or engaged gear pairs for
the torque transfer of the reverse gear is three.
[0080] Alternative paths for transmitting some of the
above-mentioned torque flow paths of the DCT 1 are possible to be
provided.
[0081] FIG. 10 illustrates an assembly 100 of a double-sided
coupling device 102 with its neighboring gearwheels 101, 103 for
engagement. The assembly 100 comprises a shaft 104 with the two
coaxially mounted idler gears 101, 103 on two bearings
respectively. The coupling device 102 is provided between the idler
gear 101 on the left and the idler gear 103 on the right. The
coupling device 102 is configured to move along the shaft 104 to
selectively engage any of the idler gears 101, 103 at one time. In
other words, the idler gears 101, 103 can alternatively be brought
into non-rotating engagement with the shaft 104 by the coupling
device 102. Symbols for showing the assembly 100 is provided at the
right hand side of FIG. 10.
[0082] FIG. 11 illustrates an assembly 110 of a single-sided
coupling device 112 with its neighboring gearwheel 113 for
engagement. The assembly 110 comprises a shaft 114 with the one
coaxially mounted idler gear 113 on a bearing. The coupling device
112 is provided next to the idler gear 113 on the left side. The
coupling device 112 is configured to move along the shaft 114 to
engage or disengage the idler gears 113. In other words, the idler
gear 113 can be brought into non-rotating engagement with the shaft
114 by the single-sided coupling device 112. Symbols for showing
the assembly 110 are provided at the right hand side of FIG.
11.
[0083] FIG. 12 illustrates an assembly 120 of an idler gearwheel
121 that is rotatably supported by a shaft 122 on a bearing 123.
The idler gearwheel 121 is coaxially mounted onto the shaft 122 via
the bearing 123. The bearing 123 enables the idler gearwheel 121 to
be freely rotated around the shaft 122. Symbols that represent the
assembly 120 are provided at the right hand side of the FIG.
12.
[0084] FIG. 13 illustrates an assembly 130 of a fixed gearwheel 132
that is supported on a shaft 131. The fixed gearwheel 132 is
coaxially mounted onto the shaft 131 such that the gearwheel 132 is
fixed to the shaft 132. The fixed gearwheel 132 and the shaft 131
are joined as one single body such that torque of the fixed
gearwheel 132 is transmitted to the shaft 131 directly, and vice
versa.
[0085] A number of fixed gearwheels are rigidly connected to the
input shafts 20, 22 and other shafts 14, 38, 40, 50. A symbol as
used in the previous figures for such a fixed gearwheel is provided
on the left side in FIG. 13. The more commonly used symbol for such
a fixed gearwheel is provided on the right side in FIG. 13.
[0086] FIG. 14 illustrates a cross-section through a crankshaft 2
of an internal combustion engine according to the embodiment of the
DCT 1. In FIG. 14, a crankshaft 2 of an internal combustion engine,
which is not shown here, is non-rotatably connected to the housing
4 of a double clutch 6. The double clutch 6 includes an inner
clutch disk 8 and an outer clutch disc 10, which can be brought
into non-rotating engagement with the housing 4 via control
elements that are not illustrated here. The solid input shaft 20 is
non-rotatably connected to the clutch disk 8, and extends all the
way through the hollow shaft 22. Similarly, the hollow input shaft
22 is non-rotatably connected to the other clutch disc 10.
[0087] The clutch housing 4 has a larger outer diameter around the
inner clutch disc 8 than that around the outer clutch disc 10.
Correspondingly, the inner clutch disc 8 has a larger outer
diameter than that of the outer clutch disc 10 inside the clutch
housing 4. The fact that the larger inner clutch disc 8 on the
solid input shaft 20 drives the first gear makes the DCT 1
robust.
[0088] The above-mentioned eight torque flow paths not only provide
viable solutions to generate eight gears (i.e. seven-forward &
one rearward gears) of the DCT 1, but also offer possibilities of
switching from one gear to the other efficiently. For example, gear
jumping from the third gear to the fifth gear is efficiently
provided by the double-meshing of the idler fifth gear 64 and the
idler third gear 62, via an intermediate gearwheel, namely the
fixed wheel third gear 25. The fixed wheel third gear 25 also
serves as the fixed wheel fifth gear 26. The gear jump between the
third and the fifth does not require stopping the solid input shaft
20. Furthermore, the double-meshing of the idler third gear 62 and
idler fifth gear 64 avoids the need of providing two separate fixed
gearwheels on an input shaft. In other words, less space is
required on the hollow input shaft 22 because two fixed gearwheels
25, 26 are combined into a single one. The DCT 1 can thus be made
lighter and cheaper by the reduction of one gearwheel.
[0089] The park-lock gearwheel 39 is a gearwheel fixed onto the
upper layshaft 40 for providing a park-lock. The park-lock is a
wheel which is provided with a ratchet device, with a click device
having a rack element, a claw or similar. The park-lock keeps the
upper layshaft 40 and the output shaft 14 from rotating, which stop
a vehicle with the DCT 1 from running when the vehicle is parked.
When using the park-lock, the park-lock gearwheel 39 on the upper
layshaft 40 can be easily engaged to lock the output shaft 14, via
the upper pinion 41, via the output gearwheel 12 and stopping the
output shaft 14 from rotating.
[0090] FIG. 15 illustrates an alternative front view of the
expanded side view of the double clutch transmission 1 in FIG. 2.
FIG. 15 comprises parts that are similar to that of FIGS. 1 to 14.
The similar parts have similar or same part reference numbers.
Descriptions of the similar or the same parts are hereby
incorporated by reference.
[0091] Although the above description contains much specificity,
these should not be construed as limiting the scope of the
embodiment but merely providing illustration of the foreseeable
embodiment. Especially the above stated advantages of the
embodiment should not be construed as limiting the scope of the
embodiment but merely to explain possible achievements if the
described embodiment is put into practice. Thus, the scope of the
embodiment should be determined by the claims, rather than by
examples given.
[0092] While at least one exemplary embodiment has been presented
in the foregoing summary and detailed description, it should be
appreciated that a vast number of variations exist. It should also
be appreciated that the exemplary embodiment or exemplary
embodiments are only examples, and are not intended to limit the
scope, applicability, or configuration in any way. Rather, the
foregoing summary and detailed description will provide those
skilled in the art with a convenient road map for implementing an
exemplary embodiment of the invention, it being understood that
various changes may be made in the function and arrangement of
elements described in an exemplary embodiment without departing
from the scope as set forth in the appended claims and their legal
equivalents.
* * * * *