U.S. patent application number 12/024463 was filed with the patent office on 2008-08-14 for transmission unit, in particular a multi-range transmission.
Invention is credited to Dieter Glockler.
Application Number | 20080194372 12/024463 |
Document ID | / |
Family ID | 37076191 |
Filed Date | 2008-08-14 |
United States Patent
Application |
20080194372 |
Kind Code |
A1 |
Glockler; Dieter |
August 14, 2008 |
TRANSMISSION UNIT, IN PARTICULAR A MULTI-RANGE TRANSMISSION
Abstract
A transmission unit, especially a multirange transmission,
includes two superposition gears that are embodied as triple-shaft
planetary gears, a continuously variable transmission in the form
of a traction gear, and a way for controlling the transmission
ratio on the traction gear. The individual superposition gears and
the continuously variable transmission are coupled to each other
via one respective connecting gear. The second shaft of the first
superposition gear and a shaft of the second superposition gear can
be alternatively joined to the gear output via a shiftable clutch.
The second shaft of the first superposition gear can be connected
in a torsion-proof manner to the third shaft of the second
superposition gear. The first shaft of the second superposition
gear is joined to a shaft of the first superposition gear via
another shifting clutch.
Inventors: |
Glockler; Dieter; (Ulm,
DE) |
Correspondence
Address: |
TAYLOR & AUST, P.C.
P.O. Box 560, 142. S Main Street
Avilla
IN
46710
US
|
Family ID: |
37076191 |
Appl. No.: |
12/024463 |
Filed: |
February 1, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/EP2006/007472 |
Jul 27, 2006 |
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12024463 |
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Current U.S.
Class: |
475/210 |
Current CPC
Class: |
F16H 2037/0866 20130101;
F16H 37/0846 20130101; F16H 2037/104 20130101 |
Class at
Publication: |
475/210 |
International
Class: |
F16H 37/08 20060101
F16H037/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 2, 2005 |
DE |
10 2005 036 803.4 |
Nov 17, 2005 |
DE |
10 2005 054 720.6 |
Claims
1. A transmission unit, comprising: a transmission input; a
transmission output; a first superposition gear; a second
superposition gear, each of said first and second superposition
gears formed as a three-shaft planetary gear and including a first
shaft, a second shaft, a third shaft, a sun wheel, an internal
gear, a bridge, a plurality of planet wheels, said first, second,
and third shafts of each of said first and second superposition
gears each being formed respectively by a corresponding one of said
sun wheel, said internal gear, said bridge, said plurality of
planet wheels, and a plurality of elements connected thereto in a
rotationally fixed manner, said first shaft of said first
superposition gear being at least indirectly connected in a
rotationally fixed manner to said transmission input, said second
shaft of said first superposition gear and said second shaft of
said second superposition gear being at least indirectly connected
in a rotationally fixed manner to said transmission output; a
continuously variable transmission formed as a flexible drive
transmission; a device for controlling a gear ratio at said
flexible drive transmission; a first connecting gear; a second
connecting gear, said first superposition gear being coupled with
said continuously variable transmission via said first connecting
gear, said second superposition gear being coupled with said
continuously variable transmission via said second connecting gear,
said first and second connecting gears each including a gear ratio
stage, said third shaft of said first superposition gear being
connected to said continuously variable transmission via said first
connecting gear, said third shaft of said second superposition gear
being connected to said continuously variable transmission via said
second connecting gear; a first shiftable clutch; and a second
shiftable clutch, said second shaft of said first superposition
gear and said third shaft of said second superposition gear being
connected to said transmission output via said first shiftable
clutch, said second shaft of said first superposition gear being
connected in a rotationally fixed manner to said third shaft of
said second superposition gear, said first shaft of said second
superposition gear being connected to said third shaft of said
first superposition gear via said second shiftable clutch.
2. The transmission unit according to claim 1, wherein said
transmission input and said transmission output have an eccentric
configuration, said three-shaft planetary gear of said first
superposition gear being a single planetary gear having said
plurality of planet wheels of said first superposition gear between
said sun wheel of said first superposition gear and said internal
gear of said first superposition gear.
3. The transmission unit according to claim 2, wherein said
three-shaft planetary gear of said first superposition gear is a
first planetary gear and said three-shaft planetary gear of said
second superposition gear is a second planetary gear, said first
shaft of said first superposition gear and said first shaft of said
second superposition gear are each formed by one of a) said bridge
of said first planetary gear and said bridge of said second
planetary gear, respectively, and b) said plurality of elements
coupled thereto in said rotationally fixed manner, said second
shaft of said first superposition gear being formed by said sun
wheel of said first planetary gear, said second shaft of said
second superposition gear being formed by said internal gear of
said second superposition gear, said third shaft of said first
superposition gear being formed one of by said internal gear of
said first planetary gear and by at least one of said plurality of
elements coupled thereto in said rotationally fixed manner, said
third shaft of said second planetary gear being formed one of by
said sun wheel and by at least one of said plurality of elements
coupled thereto in said rotationally fixed manner.
4. The transmission unit according to claim 2, wherein said first
and second connecting gears are each formed by a reversing
gear.
5. The transmission unit according to claim 4, wherein said first
and second connecting gears are each formed by a spur gear stage
including an even number of intermeshing spur gears.
6. The transmission unit according to claim 5, wherein at least one
of a) one said intermeshing spur gear of said first connecting gear
one of is formed by said third shaft of said first superposition
gear and forms a structural unit with same, and b) one said
intermeshing spur gear of said second connecting gear one of is
formed by said third shaft of said second superposition gear and
forms a structural unit with same.
7. The transmission unit according to claim 2, wherein said sun
wheel of said second superposition gear is provided as a function
of an overall transmission spread to be achieved.
8. The transmission unit according to claim 2, wherein said first
superposition gear has said gear ratio of said continuously
variable transmission, which corresponds to a maximum theoretically
possible said gear ratio at said continuously variable
transmission.
9. The transmission unit according to claim 2, wherein said sun
wheel of said first superposition gear has a reference circle
diameter that is from 2 to 3 times smaller than that of said
internal gear of said first superposition gear.
10. The transmission unit according to claim 2, wherein said sun
wheel of said first superposition gear has a reference circle
diameter that is from 2 to 2.6 times smaller than that of said
internal gear of said first superposition gear.
11. The transmission unit according to claim 2, wherein said sun
wheel of said second superposition gear has a reference circle
diameter that is from 2 to 3 times smaller than that of said
internal gear of said second superposition gear.
12. The transmission unit according to claim 2, wherein said sun
wheel of said second superposition gear has a reference circle
diameter that is from 2 to 2.6 times smaller than that of said
internal gear of said second superposition gear.
13. The transmission unit according to claim 2, further including a
hollow shaft, wherein said three-shaft planetary gear of said first
superposition gear is a first planetary gear and said three-shaft
planetary gear of said second superposition gear is a second
planetary gear, said sun wheel of said first planetary gear and
said sun wheel of said second planetary gear being connected to one
another in a rotationally fixed manner via said hollow shaft.
14. The transmission unit according to claim 2, wherein said first
connecting gear includes a first spur gear which is formed by said
internal gear of said first superposition gear, said second
connecting gear being formed by a second spur gear that is coupled
in a rotationally fixed manner to said third shaft and by a third
spur gear that is coupled in a rotationally fixed manner to said
continuously variable transmission.
15. The transmission unit according to claim 1, wherein a gear
ratio of 1:2 to 3 is set between said third shaft of said first
superposition gear and said third shaft of said second
superposition gear.
16. The transmission unit according to claim 1, wherein a gear
ratio of 1:2.5 is set between said third shaft of said first
superposition gear and said third shaft of said second
superposition gear.
17. The transmission unit according to claim 1, wherein said
three-shaft planetary gear of said first superposition gear is a
first planetary gear and said three-shaft planetary gear of said
second superposition gear is a second planetary gear, said
plurality of planet wheels of said first superposition gear
including a planet wheel pair, said sun wheel of said first
superposition gear and said internal gear of said first
superposition gear being coupled to one another via said planet
wheel pair, said second superposition gear being positioned
downstream from said first superposition gear in an axial
direction, said second shaft of said second superposition gear
being connected in a rotationally fixed manner to said transmission
output, said first shaft of said second superposition gear being
connected in a rotationally fixed manner to said third shaft of
said first planetary gear, said first shiftable clutch being
positioned between said second shaft of said first planetary gear
and said second shaft of said second planetary gear, said second
shiftable clutch being positioned between said third shaft of said
first planetary gear and said first shaft of said second
superposition gear.
18. The transmission unit according to claim 17, wherein said first
shaft of said first planetary gear is formed by said internal gear
of said first superposition gear, said second shaft of said first
planetary gear is formed by said sun wheel of said first
superposition gear, and said third shaft of said first planetary
gear is formed by said bridge of said first superposition gear.
19. The transmission unit according to claim 17, wherein said first
shaft of said second superposition gear is formed by said bridge of
said second superposition gear, said second shaft of said second
superposition gear is formed by said internal gear of said second
superposition gear, and said third shaft of said second
superposition gear is formed by said sun wheel of said second
superposition gear.
20. The transmission unit according to claim 17, wherein said
transmission input, said transmission output, and said first and
second superposition gears are coaxial relative to one another.
21. The transmission unit according to claim 1, further comprising
a traction device and a device configured for adapting a rotational
speed of said traction device to a rotational speed of said
transmission input, said continuously variable transmission being a
positive-fit said flexible drive transmission, said traction device
being formed by one of a belt, a chain, and a push belt.
22. The transmission unit according to claim 21, wherein said
device configured for adapting said rotational speed of said
traction device to said rotational speed of said transmission input
includes a transmitting element which is at least indirectly
coupled to said transmission input and which is in a positive-fit
mechanical linkage with said traction device.
23. The transmission unit according to claim 22, wherein said
traction device includes an outer periphery and a circumferential
profiling at said outer periphery of said traction device, said
transmitting element including an outer periphery and a profiling
at said outer periphery of said transmitting element, said
circumferential profiling of said traction device engaging with
corresponding said profiling at said outer periphery of said
transmitting element.
24. The transmission unit according to claim 23, further comprising
a swivel gear, wherein said continuously variable transmission
includes two disk systems, said transmission input includes a
transmission input shaft, said transmitting element is configured
in parallel with said transmission input shaft, and, for
maintaining a tension in said traction device, said swivel gear is
configured for swiveling said disk systems which are associated
with said transmitting element.
25. The transmission unit according to claim 23, further comprising
a clamping device, wherein said transmitting element is configured
in parallel with said transmission input shaft, and, for
maintaining a tension, said clamping device, which is supported so
as to be one of displaceable and pivotable, is associated with said
traction device.
26. The transmission unit according to claim 1, wherein said
continuously variable transmission includes two disk systems each
including a plurality of disks, said device for controlling said
gear ratio at said flexible drive transmission including a
plurality of actuators for adjusting a distance between respective
ones of said plurality of disks of said disk systems.
27. The transmission unit according to claim 1, further comprising
a switchable starter unit, said transmission input being connected
to said switchable starter unit.
28. The transmission unit according to claim 1, further comprising
a device for reversing a rotational direction.
29. The transmission unit according to claim 28, wherein said
device for reversing said rotational direction includes a reversing
switch assembly.
30. The transmission unit according to claim 1, wherein at least
one of said first and second shiftable clutches is one of a
friction clutch and a synchronously shiftable clutch.
31. The transmission unit according to claim 1, further comprising
a starter element which is upstream from said transmission
input.
32. The transmission unit according to claim 31, wherein said
starter element is one of a hydrodynamic rotational speed/torque
converter and a hydrodynamic clutch.
33. The transmission unit according to claim 32, further comprising
a lock-up clutch which is associated with said starter element.
34. The transmission unit according to claim 31, wherein said
starter element is a multi-plate clutch.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of PCT application No.
PCT/EP2006/007472, entitled "TRANSMISSION UNIT, PARTICULARLY
MULTIRANGE TRANSMISSION", filed Jul. 27, 2006, which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a transmission unit, in particular
a multirange transmission.
[0004] 2. Description of the Related Art
[0005] Transmission systems in the form of power distribution
transmissions embodied as superposition gears are known in numerous
designs. Reference is made to the following documents by way of
example:
[0006] 1. U.S. Pat. No. 6,921,349 B2
[0007] 2. DE 197 55 612 A1
[0008] 3. EP 1061287 A2
[0009] 4. DE 43 08 761 A1
[0010] 5. DE 887 457 C
[0011] The design according to DE 197 55 612 A1 includes a
transmission input shaft and a continuously variable step-up gear
coupled to the transmission output shaft in the form of a flexible
drive having an input and an output, the input being connected in a
rotationally fixed manner to the transmission input shaft, a fixed
gear ratio stage, and a superposition gear having a first input
stage which is connected in a rotationally fixed manner to the
output of the continuously variable step-up gear. In addition, a
second input stage is provided which by way of a first clutch may
optionally be connected to the transmission input shaft via the
fixed gear ratio stage, in addition to an output stage which is
coupled to the transmission output shaft in a rotationally fixed
manner. On the drive side the fixed gear ratio stage is coupled in
a rotationally fixed manner to the transmission input shaft, and
with respect to the fixed gear ratio stage on the output side the
first clutch is positioned in such a way that it optionally
connects the second input stage of the superposition gear on the
output side to the fixed step-up gear. A functionally reliable
multirange transmission may be easily provided by way of this
approach. This approach offers the advantage that in a multirange
transmission produced by a combination of a continuously variable
step-up gear and a geared-neutral range, high meshing speeds in the
region of the first clutch may be avoided, since as a result of the
fixed gear ratio stage the clutch is provided at a location after a
corresponding transformation of the high rotational speed of the
drive shaft to the low rotational speed. This reduces wear and
increases the service life of the first clutch. However, a
significant disadvantage lies in the direct connection between the
continuously variable transmission, also referred to as CVT, and
the transmission input and, therefore, the drive shaft. The
continuously variable transmission is thus always coupled to the
rotational speed of the drive motor. Load is reduced on the
superposition gear in a region of high rotational speeds of the
drive shaft, i.e., lower gear ratios of the continuously variable
step-up gear, by providing a second clutch which optionally
connects the first input stage to the output stage of the
superposition gear. This establishes a rigid connection between the
output shaft of the continuously variable step-up gear and the
output shaft, thereby bridging the superposition gear in the torque
flow. Another significant problem of power transmission via the
continuously variable step-up gear is that, as a result of its
dimensions, the step-up gear is able to transmit only a maximum
allowable torque, since otherwise impermissible slip conditions
would be observed at very high loads which would result in
increased wear on the traction way. Because of the direct coupling
of the continuously variable transmission to the transmission
input, however, the latter is continuously exposed to these
conditions. In other words, the input of the CVT is impinged on by
the rotational speed at the transmission input, and therefore, by
the drive motor.
[0012] A transmission unit is known from U.S. Pat. No. 6,921,349 B2
which has a structure that has been modified such that the load on
the flexible drive transmission is significantly reduced, thus
ensuring high power, in particular higher power than in a design
according to DE 197 55 612 A1, to be transmitted via this flexible
drive transmission. In this design the transmission unit is
likewise embodied as a superposition gear unit. This superposition
gear includes a transmission input and a transmission output, in
addition to two superposition gears located between the
transmission input and transmission output and connected to one
another. Each of the two superposition gears is designed as a
three-shaft planetary gear. Both are interconnected to form a
four-shaft planetary gear. A continuously variable transmission in
the form of a flexible drive transmission is connected between the
first superposition gear and the second superposition gear. Each
planetary gear includes a sun wheel, an internal gear, planet
wheels, and a bridge. The individual shafts are formed by the sun
wheel, internal gear, or bridge of the respective superposition
gear. The transmission input is connected in a rotationally fixed
manner to a first shaft of the first superposition gear and to a
first shaft of the second superposition gear. The transmission
output is connected in a rotationally fixed manner to a second
shaft of the first superposition gear and to a second shaft of the
second superposition gear. The coupling of the two three-shaft
planetary gears to form a four-shaft planetary gear occurs by
connection of the first and second shafts of the first and second
superposition gears. The configuration of the continuously variable
transmission in the form of a flexible drive transmission is
achieved between the third shafts of the first and second
superposition gears. The term "shaft" is understood in a functional
sense, and includes either the individual elements of the planetary
gear (sun wheel, internal gear, or bridge), or the elements
connected thereto in a rotationally fixed manner, for example in
the form of shafts or hollow shafts. Depending on the operating
state, the individual shafts assume the function of inputs and
outputs. Thus, for the transmission of power from the transmission
input shaft to the transmission output shaft via the continuously
variable transmission, the first superposition gear includes one
input and two outputs. The input is formed by the first shaft,
whereas the first output, which is at least indirectly connected to
the continuously variable transmission, is formed by the third
shaft, and the second output which is coupled in a rotationally
fixed manner to the transmission output shaft is formed by the
second shaft. In this operating state the second superposition gear
includes one input and one output, the input likewise being coupled
to the transmission input shaft and formed by the first shaft of
the second superposition gear, and the output being formed by the
second shaft. The third shaft is connected to the continuously
variable transmission. In addition, a way is provided for changing
the gear ratio at the transmission. One of the two superposition
gears--the first or the second superposition gear--has pairs of
intermeshing planetary gears between the sun wheel and the internal
gear. The sun wheel and internal gear are rotatably supported on
the bridge. The pairs of intermeshing planetary gears are also
referred to as double-barreled planet wheels. On account of the
design of the second superposition gear as a planetary gear having
pairs of intermeshing planetary gears, also referred to as
double-barreled planetary gears, for a portion of the overall
operating range it is ensured that the CVT operates at maximum
rotational speed, whereby a change may also be made with regard to
the gear ratio at the individual disks at maximum engine speed;
i.e., rotation above the zero level is possible, thus enabling a
geared-neutral state as well as a change in rotational direction to
be achieved by the transmission according to the invention. The
double-barreled design offers the advantage that for an increased
rotational speed thus produced at the output coupled to the
continuously variable transmission, in particular the internal gear
of this planetary gear, a reduction at the output of the other
respective planetary gear, in particular the internal gear, which
is coupled to the continuously variable transmission is achieved
corresponding to the design of the other planetary gear. According
to this design, however, it is not possible to allow the
continuously variable transmission to operate multiple times over
the entire operating range at maximum rotational speed.
[0013] A multirange transmission is known from EP 1 061 287 A2.
This multirange transmission is characterized by a three-shaft
planetary gear which may be connected to the transmission output
via a continuously variable transmission. Three-shaft planetary
gears are always traversed in parallel, the coupling to the
transmission output being achieved by way of different gear ratios,
which in this case are implemented via spur gear stages which may
be respectively coupled to the transmission output via individual
clutch units. In other words, only one gear ratio stage, which is
fixed, is provided downstream from the continuously variable
transmission. As a result, however, the continuously variable
step-up gear is consistently varied via a fixed gear ratio.
Depending on the output gear ratio selected, this results in
individual maximum allowable gear ratio ranges. This also applies
analogously to the design described in DE 887 457 and DE 43 08
761.
[0014] What is needed in the art is a multirange transmission
which, in addition to the advantages achieved by the transmission
configurations previously described, provides an improved
transmission configuration, whereby in particular operation above
the zero level is possible. What is also needed is to reduce the
load on the flexible drive transmission during operation. What is
further needed is a design having the improved transmission
configuration, described on the basis of U.S. Pat. No. 6,921,349
B2, which overcomes the referenced disadvantages from the prior
art.
SUMMARY OF THE INVENTION
[0015] The present invention provides that the transmission unit is
designed as a multirange transmission. This multirange transmission
includes a transmission input and a transmission output, in
addition to two interconnected superposition gears located between
the transmission input and transmission output. Each of the two
superposition gears is designed as a three-shaft planetary gear. A
continuously variable transmission in the form of a flexible drive
transmission is connected between the first superposition gear and
the second superposition gear. Each planetary gear includes a sun
wheel, an internal gear, planet wheels, and a bridge. The
individual shafts are formed by the sun wheel, internal gear, or
bridge of the respective superposition gear, or by an element
connected thereto in a rotationally fixed manner. The transmission
input is connected at least indirectly, i.e., directly or
indirectly via additional transmitting elements, in a rotationally
fixed manner to a first shaft of the first superposition gear.
According to the invention, a shiftable clutch is provided between
the first shaft of the second superposition gear and a shaft of the
first superposition gear. The transmission output is connected in a
rotationally fixed manner to a second shaft of the second
superposition gear, and may be connected in a rotationally fixed
manner to a second shaft of the first superposition gear via an
additional shiftable clutch. The configuration of the continuously
variable transmission in the form of a flexible drive transmission
is achieved between the third shafts of the first and second
superposition gears. The term "shaft" is understood in a functional
sense, and includes either the individual elements of the planetary
gear (sun wheel, internal gear, or bridge), or the elements
connected thereto in a rotationally fixed manner, for example in
the form of shafts or hollow shafts.
[0016] Depending on the operating range, the individual shafts
assume the function of inputs and outputs. Thus, for the
transmission of power from the transmission input shaft to the
transmission output shaft via the continuously variable
transmission, the first superposition gear includes one input and
two outputs. The input is formed by the first shaft, whereas the
first output, which is at least indirectly connected to the
continuously variable transmission, is formed by the second shaft,
and the third output which is coupled in a rotationally fixed
manner to the transmission output shaft is formed by the third
shaft. In this operating state the second superposition gear
includes one input and one output, the input being coupled to the
third shaft of the first superposition gear and being formed by the
first shaft of the second superposition gear, and the output being
formed by the second shaft. The third shaft is connected to the
continuously variable transmission. In addition, a way is provided
for changing the gear ratio at the transmission.
[0017] The coupling between the superposition gears and the
continuously variable transmission is achieved in each case via a
connecting gear in the form of gear ratio stages. In the simplest
case this is achieved by way of a simple spur gear set having an
even number of spur gears, in which case the respective input spur
gear may be formed directly by the output of the superposition
gear. Both clutches are shiftable, and as a rule power is
transmitted by first shifting the first clutch, and with
synchronism between the first shaft of the second superposition
gear and the third shaft of the second superposition gear, or the
second shaft of the first superposition gear, by shifting the
second clutch and releasing the first clutch. Depending on the
clutch design, the clutches may also be engaged in an overlapping
or consecutive manner. However, this is preferably performed
without interruption of tensile force, and the second clutch is
shifted with synchronism between the second and third shafts of the
superposition gear. For this design as well, the input of the
continuously variable transmission in the form of the flexible
drive transmission is not bound to the rotational speed of the
drive motor; i.e., there is no rotationally fixed connection
between the input of the transmission unit and the continuously
variable transmission. This is achieved solely via the first
superposition gear. Since by necessity one of the shafts of the
first superposition gear is not fixed, the first superposition gear
does not specify a fixed gear ratio. The continuously variable
transmission operates over the entire operating range at maximum
rotational speed at maximum engine speed. On account of the two
shiftable clutches and their alternating actuation, resulting in
bridging of the second superposition gear, over the entire
operating range the continuously variable transmission changes
twice, in a manner of speaking, with regard to the rotational
speed, for example in a range of 2000 to 4800 rpm.
[0018] The key factor is that the alternation of clutches for the
second planetary gear takes place without interruption of tensile
force. The transmission input shaft and the third shaft of the
second superposition gear, or the second shaft of the first
superposition gear, run synchronously.
[0019] The approach according to the invention is characterized in
that in all operating ranges there is no direct, rotationally fixed
coupling between the transmission input shaft and the continuously
variable transmission, in particular the respective disk system
which functions as the input of the continuously variable
transmission; instead, this coupling is achieved via a
superposition gear. Thus, although a fixed gear ratio is achieved
over a stage due to the coupling between the superposition gear and
the continuously variable transmission, the individual variables of
rotational speed and torque at the input of the continuously
variable transmission are always a function of the conditions at
the first superposition gear; i.e., when power is transmitted via
the flexible drive transmission the greatest influence is on the
rotational speed at the transmission output shaft, which in turn
exerts influence on the first superposition gear and thus affects
the amount of power that can be transmitted via the first
superposition gear, as well as the rotational speed of the third
shaft of the first superposition gear. As a result, unnecessarily
high loads on the continuously variable transmission are avoided at
higher rotational speeds. The input of the continuously variable
transmission is therefore no longer directly bound to the
rotational speed at the transmission input, and thus to the drive
motor coupled thereto. The rotational speed at the transmission
output of the transmission unit may be modified by control of the
continuously variable transmission. Due to the capability for
shifting the two clutches, a multirange transmission is realized
which is characterized by utilization of the gear ratio range of
the continuously variable transmission in each of the individual
operating ranges. In other words, the continuously variable
transmission is traversed in both directions in each operating
range. The overall spread of the transmission is thus increased for
a flexible drive transmission of the same or smaller dimension.
[0020] Depending on the assignment of the functions of the
individual shafts to the elements of the individual superposition
gears, systems may be produced having an eccentric configuration of
transmission input with respect to transmission output, or a
coaxial configuration.
[0021] According to a first design, the first shafts of the two
superposition gears are each formed by the bridge for the
individual superposition gear. The second shaft of the first
planetary gear is formed by the sun wheel, and the second shaft of
the second planetary gear is formed by the internal gear. The third
shafts, which are at least indirectly coupled to the flexible drive
transmission, are formed by the internal gear of the first
planetary gear and the sun wheel of the second planetary gear.
[0022] According to a second approach, the multirange transmission
includes a transmission input and a transmission output, between
which a continuously variable transmission, a first three-shaft
planetary gear, and a second three-shaft planetary gear are
provided. The continuously variable transmission and the planetary
gear are configured in parallel. The first three-shaft planetary
gear is designed as a superposition gear including a sun wheel,
internal gear, bridge, and double planet wheel sets between the
internal gear and sun wheel, the individual shafts each being
formed by the sun wheel, internal gear, or bridge, or by the
elements which are respectively connected thereto in a rotationally
fixed manner. A first shaft is at least indirectly coupled in a
rotationally fixed manner to the transmission input. The second
shaft and the third shaft are at least indirectly coupled in a
rotationally fixed manner to an input or output of the continuously
variable transmission, which is present in the form of a flexible
drive transmission. A shiftable clutch is provided directly between
the second shaft of the first superposition gear and the second
shaft of the second superposition gear. An additional shiftable
clutch is provided between the first shaft of the second
superposition gear and the third shaft of the first superposition
gear. The second superposition gear is situated downstream from the
first superposition gear, and may be coupled thereto by way of
clutch units. The second superposition gear is likewise designed as
a three-shaft gear including a third shaft which is connected in a
rotationally fixed manner to the second shaft of the first
planetary gear, a second shaft which is connected in a rotationally
fixed manner to the transmission output and which may be connected
in a rotationally fixed manner to the second shaft of the first
planetary gear via the second shiftable clutch, and a first shaft
which may be connected in a rotationally fixed manner to the third
shaft of the first planetary gear via a first shiftable clutch
unit.
[0023] The two shiftable clutches may be selectively shifted, i.e.,
individually or together. The shifting may also be performed in an
overlapping manner. The shiftable clutches are designed as clutches
which may be operated with slip, or as synchronously shiftable
clutches. Depending on the operating range, the individual shafts
assume the function of inputs and outputs.
[0024] According to the invention, in one embodiment corresponding
to the second approach the first shaft of the first planetary gear
is formed by the internal gear, the second shaft is formed by the
sun wheel, and the third shaft is formed by the bridge. The third
shaft of the second superposition gear is formed by the sun wheel,
the first shaft is formed by the bridge, and the second shaft is
formed by the internal gear. When the additional shiftable clutch
between the first shaft of the second planetary gear and the third
shaft of the first planetary gear is actuated, the two planetary
gears are connected to form a four-shaft planetary gear; i.e., the
gear ratio present at the output of the first planetary gear is
transformed once again at the transmission output. When the other
shiftable clutch is actuated, there is synchronism between the
first shaft and the third shaft of the second superposition gear,
thereby achieving a gear ratio of 1:1.
[0025] The internal gear and sun wheel for the two planet wheel
sets may be designed in any given manner. However, the overall
design, in particular the connection between the outputs and the
continuously variable transmission, must be taken into account. The
overall spread of the transmission may be influenced by the design
of the second superposition gear. For example, the overall spread
of the transmission may be directly influenced by varying the sun
wheel, in particular its diameter, while maintaining the design of
the internal gear. Enlarging the diameter increases the overall
spread, while decreasing the diameter reduces the overall spread.
The first planet wheel set is designed as a function of the spread
of the CVT; i.e., the internal gear and sun wheel are designed
according to an embodiment corresponding to the first approach, for
example with a CVT spread to be achieved that is approximately 2.5,
in such a way that the ratio of the sun wheel to the internal gear
corresponds to the ratios achieved with the CVT. (The shafts run
synchronously during alternation of the clutches.)
[0026] The continuously variable transmission may have numerous
designs for both approaches, and is preferably designed as a
positive-fit flexible drive transmission. The flexible drive
transmission includes two disk systems, a first disk system and a
second disk system, whereby the individual disks, preferably at
least one disk, are displaceable relative to one another for
changing the gear ratio. Belts, chains, and push belts are used as
traction way.
[0027] For the design of the flexible drive transmission having two
disk systems, wherein the distance between the disks of a disk
system may be varied by way of the pressure force on the disks of a
disk system, and this variable is used as a direct control variable
or a variable which at least indirectly characterizes same, the way
for controlling the gear ratio includes corresponding actuating
devices for impinging on the individual disks or displacing same.
The disks may be operated by electrohydraulic ways, for example. It
is possible for a corresponding actuating device to be associated
with only one disk system for actively changing the operating
radius for the traction way, while associated with the other disk
system are pretensioned spring units, for example, which, depending
on the change in the distance between the individual disks, and
thus of the operating radius, at the disk system which may be
actively controlled by the actuating device, allow the pressure
force to be automatically adjusted and therefore the operating
radius to be set. Another possibility is to actuate both disk
systems. With regard to the specific design there are a number of
possibilities known from the prior art, which therefore will not be
discussed in greater detail.
[0028] The gear ratio stages provided between the first and second
superposition gears and the continuously variable transmission
(CVT) are designed according to the maximum allowable rotational
speed at the CVT.
[0029] For the approach according to the invention, a control is
also provided which modifies the gear ratio on the flexible drive
transmission, in particular by changing the distance between the
disks of a disk system. This is achieved, for example, as a
function of the engine speed, the desired rotational speed at the
transmission output shaft, the position of the gas pedal, and other
influencing variables. There are a number of possibilities for the
control, for which conventional approaches may be used.
[0030] For reversing the direction of rotation, a reversing gear or
a corresponding system may also be provided which allows the
rotational direction of the transmission input shaft to be
reversed. However, it is also possible to make full use of the
spread range and operate the second superposition gear above the
zero level.
[0031] In addition, a starter unit as previously described, for
example in the form of a hydrodynamic converter, a hydrodynamic
clutch, or a mechanical clutch, for example in the form of a
wet-running multi-plate clutch, may be associated with the
transmission unit according to the invention so as not to transmit
the full load to the continuously variable transmission in the
start-up state.
[0032] According to one particularly advantageous refinement, slip
resulting at the continuously variable transmission at high power
may be prevented by use of a way for adapting the rotational speed
of the traction way to the rotational speed of the drive shaft. A
further increase in the amount of transmittable power may thus be
achieved.
[0033] The way for adapting the rotational speed of the traction
way to the rotational speed of the transmission input includes a
transmitting element which is at least indirectly coupled to the
transmission input and mechanically linked to the traction way in a
positive-fit manner. The traction way is provided with
circumferential profiling at the outer periphery which engages with
correspondingly designed profiling at the outer periphery of the
transmitting element. Another possibility is to design the traction
way as a chain or as a combination of a belt and chain, in which
case the transmitting element is designed as a sprocket wheel;
i.e., the design consistently results from the unchanged
positioning of the transmitting element relative to the traction
way. According to a first approach, adjustments to the traction way
upon changes in the operating radii when the disks of the
continuously variable transmission are displaced and the rotational
speed of the traction way is synchronously adapted to the
rotational speed of the transmission input are compensated for by
use of a clamping device, in particular a tensioning roller. The
tensioning roller may be swiveled relative to the traction way and
stationarily supported. The transmitting element is at least
indirectly coupled to the transmission input. This means that the
transmitting element is either coupled in a rotationally fixed
manner to the transmission input or is coupled thereto via
additional transmitting elements. To ensure rotation of the
transmitting element in the same rotational direction as the
operating direction of the traction way, the traction way is either
directly coupled in a rotationally fixed manner to the drive shaft
or transmission input, or is coupled via additional transmitting
elements such as a spur gear set, in which case the number of
intermeshing transmitting elements is odd. The transmitting
elements may also be provided so as to be pivotable relative to the
traction way. The transmitting elements are then used
simultaneously as a clamping element for adapting the rotational
speed to the rotational speed at the transmission input. The
gearwheel prevents slip on the smaller operating radius of the
flexible drive transmission. The torque is transmitted over large
and small operating radii, thus achieving a larger transmitting
surface.
[0034] According to a further approach, for taut and slip-free
guiding of the traction way the deviations from the peripheral
length of the traction way theoretically required in this state for
secure transmission of torque, resulting from differing
displacement of the two disk systems, i.e., nonuniform
displacement, are compensated for by the capability of the disk
systems to swivel about the transmitting element. The elements on
the shafts connected in a rotationally fixed manner to the disk
systems and the elements supported thereon--the output of the first
fixed gear ratio stage and the input of the second fixed gear ratio
stage--are also swiveled. These elements specify the swivel radius.
The swiveling always occurs in the circumferential direction, i.e.,
about the transmitting element.
[0035] Operation above the zero level is possible for certain
designs of the transmission. Otherwise, reverse shifting is
provided for reversing the rotational direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] The above-mentioned and other features and advantages of
this invention, and the manner of attaining them, will become more
apparent and the invention will be better understood by reference
to the following description of embodiments of the invention taken
in conjunction with the accompanying drawings, wherein:
[0037] FIG. 1 shows one design of a transmission unit according to
the present invention;
[0038] FIG. 2 shows an advantageous refinement according to FIG. 1;
and
[0039] FIG. 3 shows one particularly advantageous design of an
approach according to the present invention in a coaxial
design.
[0040] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplifications set out
herein illustrate embodiments of the invention, and such
exemplifications are not to be construed as limiting the scope of
the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0041] Referring now to the drawings, and more particularly to FIG.
1, there is shown a schematically simplified illustration of the
basic design of a transmission unit 1 configured according to the
invention in the form of a superposition gear unit, in particular
in the form of a multirange transmission 2. The transmission unit
includes a transmission input E and a transmission output A. The
transmission input E and transmission output A have an eccentric
configuration. The offset is achieved by way of an intermediate
gear stage 50. The transmission input E is at least indirectly
connected to a drive motor, whereas for use in vehicles the output
may be indirectly coupled in a rotationally fixed manner to the
wheels of the vehicle to be driven. Power transmission between
transmission input E and transmission output A occurs in the
individual operating ranges, preferably at least two operating
ranges, which in each case make use of two power branches, a first
power branch 3 and a second power branch 4. According to the
invention, a continuously variable transmission 5 in the form of a
flexible drive transmission 6 is provided in the first power branch
3, whereby the input 7 of the continuously variable transmission 5
which functions as an input in at least one operating range is free
of a direct coupling with transmission input E, and is thus free of
coupling with the drive motor. In particular, a fixed gear ratio is
not provided between transmission input E and the continuously
variable transmission 5. The respective output 8 of the
continuously variable transmission 5 is free of a direct coupling
with transmission output A. For this purpose two superposition
gears 9 and 10 are provided between transmission input E and
transmission output A. The two superposition gears-first
superposition gear 9 and second superposition gear 10--are designed
as three-shaft planetary gears 11 and 12. Each planetary gear--a
planetary gear 11 which forms a first superposition gear 9 and the
planetary gear 12 which forms the second superposition gear
10--each include a first shaft, a second shaft, and a third shaft.
For the first planetary gear 11 the first shaft is denoted by
reference numeral 13, the second shaft by 14, and the third shaft
by 15, whereas for the second planetary gear 12 the first shaft is
denoted by 16, the second shaft by 17, and the third shaft by 18.
The first shaft 13 of the first planetary gear 11 is connected in a
rotationally fixed manner to input E of the transmission unit 1 or
is formed by same. The second shaft 14 may be connected to the
second planetary gear 12, and the third shaft 15 may be connected
at least indirectly to the continuously variable transmission 5,
preferably via a connecting gear 39 which includes a gear ratio
stage 19. This applies analogously to the second superposition gear
10 in the form of the second planetary gear 12. The first shaft 16
is connected to the first planet wheel set 11, in particular to the
third shaft 15, the coupling with transmission unit E occurring via
this connection. The third shaft 18 may be connected in a
rotationally fixed manner to the second shaft 14 of the first
planetary gear 11 and may be connected at least indirectly to the
continuously variable transmission 5. The connection is made via a
connecting gear 40 which includes a gear ratio stage 20. Gear ratio
stages 19 and 20 have a fixed gear ratio. The second shaft 17 is
connected in a rotationally fixed manner to output A of the
transmission unit 1. According to the invention, the first
superposition gear 9 and the second superposition gear 10 are
alternately used in the individual operating ranges as power
dividers and summing gears. To achieve the multirange operating
method, two shiftable clutches 21 and 22 are associated with the
second superposition gear 10 which optionally connect the first
shaft 16 to input E of the transmission unit 1 or to the third
shaft of the first superposition gear 9, and a second shiftable
clutch 22 optionally connects the third shaft 18 to output A of the
transmission unit 1 and thus connects output A to the continuously
variable transmission 5 via the second gear ratio stage 20. The
individual functions of the first shaft, second shaft, and third
shaft of the individual planetary gears 11, 12 are provided for the
first planetary gear 11 by a bridge 23 as the first shaft, and the
function of the second shaft 14 for connecting to the second
superposition gear 10 and via the latter to output A is provided by
the sun wheel 25. The third shaft 15 is formed by the internal gear
24. The function of the first shaft 16 of the second superposition
gear 10 is provided by the bridge 26, that of the second shaft 17
is provided by the internal gear 28, and that of the third shaft 18
is provided by the sun wheel 27. The first shiftable clutch 21
serves as the connection between the bridge 26 of the second
superposition gear 10 and the first superposition gear 9, whereas
the second shiftable clutch 22 serves as the connection between the
continuously variable transmission 5, in particular the second gear
ratio stage 20, and output A of the transmission unit 1. The
continuously variable transmission is designed as a flexible drive
transmission 6. The flexible drive transmission includes two disk
systems 33 and 35 connected by traction way 34. Depending on the
direction of power transmission, the first or second disk system
33, 35 functions as an input or an output of the continuously
variable transmission 5. The method of functioning is designed as
follows, in which at least two operating ranges may be
achieved.
[0042] The first clutch 21 is engaged in a first operating range.
In this case there is a direct connection between the first
superposition gear 9 and the first shaft 16 of the second
superposition gear 10. In this case the first superposition gear 9
functions as a power divider and the second superposition gear 10
functions strictly as a summing gear. The power flow is conducted
via the first shaft 16 of the second superposition gear 10, the
effect via the first superposition gear 9 specifying the rotational
speed at output A of the transmission unit via the third shaft 15
of the first planetary gear 11. By use of this approach the
advantageous characteristics of the system referenced in U.S. Pat.
No. 6,921,349 B2 may be maintained, and in addition the load on the
flexible drive transmission 6 may be reduced. Although a fixed gear
ratio is achieved over one stage 19 due to the coupling between the
superposition gear 9 and the continuously variable transmission 5,
the individual variables of rotational speed and torque at the
continuously variable transmission 5 are always a function of the
conditions at the first superposition gear 9 and the shifting of
the individual clutches 21, 22. Power is transmitted via the first
planetary gear 11, in particular the sun wheel 25, to the flexible
drive transmission 6, in particular the disk system 35, which in
this operating state functions as an input 7', and via the disk
system to the hollow shaft 24, and is combined at the second
planetary gear 12. As a result, unnecessarily high loads on the
continuously variable transmission 5 at higher rotational speeds
are avoided. The input of the continuously variable transmission 5
is thus no longer directly coupled to the rotational speed of the
drive motor. The rotational speed at the output may be modified by
controlling the continuously variable transmission 5. The
respective couplings between the individual disk systems 33, 35 of
the continuously variable transmission 5 and the superposition
gears 9, 10 are achieved via the corresponding connecting gears 39,
40 with fixed gear ratio stages 19, 20. For designs of the flexible
drive transmission 6 having two disk systems 33, 35, wherein the
distance between the disks of a disk system 33, 35 may be varied by
way of the pressure force on the disks of a disk system, and this
variable is used as a direct control variable or a variable which
at least indirectly characterizes same, the way 31 for controlling
the gear ratios at disk systems 33, 35 includes a corresponding
actuating device for varying the pressure force, i.e., an actuating
device for impinging on the individual disks or displacing same.
The disks may be operated by electrohydraulic ways, for example. It
is possible for a corresponding actuating device to be associated
with only one disk system 33, 35 for actively changing the
operating radius for the traction way, while associated with the
other disk system 33 or 35 are pretensioned spring units, for
example, which, depending on the change in the distance between the
individual disks, and thus of the operating radius, at the disk
system 33 or 35 which may be actively controlled by the actuating
device, allow the pressure force to be automatically adjusted and
therefore allow the operating radius to be set. Another possibility
is to actuate both disk systems, in this case disk systems 33 and
35. With regard to the specific design there are a number of
possibilities well known from the prior art, which therefore will
not be discussed in greater detail. This also applies to the
actuation methods themselves as well as specification of the
control, regulation, and reference variables for operation of the
flexible drive transmission, as well as incorporation of same into
existing drive designs. There are numerous possibilities for the
design of the continuously variable transmission 5. The coupling of
the two disk systems 33 and 35 and the transmission of force occur
in each case via traction way 34, for example in the form of a
belt, chain, or push belt.
[0043] In a second operating range II the first clutch 21 between
the continuously variable transmission and transmission output A is
disengaged, and the second clutch 22 is engaged. In this case there
is a rotationally fixed connection between transmission output A
and the third shaft 18 of the second superposition gear 10, and
thus with the output of the fixed gear ratio stage 20, which in
turn is connected to the second shaft 14 of the first superposition
gear 9. The internal gear 28 and sun wheel 27 of the second
superposition gear 10 are interconnected in a rotationally fixed
manner. The gear ratio range of the continuously variable
transmission 5 is thus used once again to achieve a higher
transmission spread, thereby reducing the load on the continuously
variable transmission. Power is transmitted from transmission input
E via the first superposition gear 9 and the first gear ratio step
19 to the continuously variable transmission 5. In the illustrated
case the first gear ratio stage 19 is designed as a spur gear
stage, the first spur gear 29 being formed by the internal gear 24
of the first superposition gear 9, whereas the second spur gear 30
which meshes therewith is connected to the shaft 32 which in this
functional state acts as an input 7 of the continuously variable
transmission, or is connected to an element of the continuously
variable transmission 5 which is connected in a rotationally fixed
manner to the first disk system 33. Power is transmitted via the
traction way 34 to a second disk system 35, which in turn is
connected via the second gear ratio stage 20, in the form of a spur
gear set 36, to the third shaft 18 of the superposition gear 10.
Here as well, the spur gear set 36 includes two spur gears, the
first spur gear 37 being connected to the second disk system 35 and
the second spur gear 38 being connected to the third shaft 18 of
the second superposition gear 10. In this functional state as well,
the distance between the disks of the first and second disk systems
33 and 35 is adjusted in each case to achieve the desired gear
ratios.
[0044] As a result of the coupling between the sun wheel and the
internal gear 27 and 28, respectively, the second superposition
gear 10 operates at a gear ratio of 1:1. In this operating range
the gear ratio of the overall transmission is specified primarily
by the continuously variable transmission 5. This results in a
change in the gear ratio at the continuously variable transmission
corresponding to the actuation of the individual disk systems. Here
as well, use is made of the possible operating range of the
continuously variable transmission by appropriate displacement of
the disks. This occurs in each case by gearing up and then gearing
down, starting, for example, with the disk system coupled to the
first superposition gear.
[0045] The transmission 1 may be coupled to the drive or the drive
motor via a starter unit.
[0046] The first superposition gear 9 and the second superposition
gear 10, as previously described, are designed as planetary gear
transmissions in the form of planetary gears 11 and 12. Each
planetary gear includes at least a sun wheel 25, an internal gear
24, a bridge 23, and planet wheels. The sun wheel 25 and the
internal gear 24 are connected to one another via simple planet
wheels. This also applies analogously to the second planetary gear
12.
[0047] With reference to an embodiment according to FIG. 1, FIG. 2
shows a particularly advantageous refinement of the transmission
unit 1 designed according to the invention in the form of a
multirange transmission 2 for achieving the transmission of high
torques. The basic design corresponds to that described in FIG. 1,
for which reason the same reference numerals are used for identical
elements. The continuously variable transmission 5 is likewise
designed as a positive-fit flexible drive transmission 6. According
to the invention, the traction way 34 is provided with profiling at
the outer periphery which allows a transmitting element 42, which
is at least indirectly coupled in a rotationally fixed manner to
transmission input E, to engage with correspondingly designed
profiling, thus allowing synchronous adaptation of the rotational
speed of the traction way 34 to transmission input E at any given
gear ratio between transmission input E and transmission output A.
This measure offers the advantage that, for the same dimensions of
the flexible drive transmission, a multiple of the power, for
example approximately three times more power, may be transmitted
than in the absence of this measure, and slip conditions at the
flexible drive transmission are avoided. Gearwheels or sprocket
wheels are used as the transmitting element 42, depending on the
choice of traction way. The changes in drum length (or operating
radius) are compensated for by way of a clamping device (not
illustrated here), such as a tensioning roller. The gearwheel
prevents slip on the small operating radius of the CVT. Both disk
systems transmit torques (large and small operating radius).
[0048] The transmitting element 42 is preferably connected in a
rotationally fixed manner to transmission input E which functions
as a drive shaft, and in conjunction with a clamping device allows
synchronous adaptation of the rotational speed of the traction way
to the rotational speed of the drive motor, i.e., transmission
input E. Slip of the traction way is thus avoided. Also possible,
however, are designs of the way for coupling the rotational speed
to the rotational speed of the drive shaft by use of a plurality of
mutually engaged transmitting elements, whereby a corresponding
gear ratio must always be selected, preferably an odd number, to
ensure the same rotational direction between the transmission input
and the operating direction of the traction way. The engagement
occurs on a continuous basis. The transmitting elements may also be
provided so as to allow swiveling. In that case the transmitting
elements are simultaneously used as a clamping element for adapting
the rotational speed of the traction way to the transmission
input.
[0049] FIG. 3 shows a schematically simplified illustration of the
basic design of a transmission unit 1 configured in a particularly
advantageous manner according to the invention in the form of a
superposition gear unit, in particular a multirange transmission 2,
by way of which operation above the zero level is also possible,
and which is characterized by a coaxial configuration of
transmission input E, transmission output A, and superposition
gears 9, 10. Transmission input E is at least indirectly connected
to a drive motor, whereas for use in vehicles transmission output A
may be at least indirectly coupled to the wheels of the vehicle to
be driven. Power transmission between transmission input E and
transmission output A occurs in the individual operating ranges,
which in each case make use of two power branches, a first power
branch 3 and a second power branch 4. For this purpose the
transmission unit 1 also includes a continuously variable
transmission 5 in the form of a flexible drive transmission 6. This
flexible drive transmission in each case includes an input 7 and an
output 8, the terms "input" and "output" being understood in a
functional sense and being free of a direct coupling with
transmission input E, and thus free of a coupling with the drive
motor. Thus, over the entire operating range no fixed gear ratio is
provided between transmission input E and the continuously variable
transmission 5. The output 8 of the continuously variable
transmission is likewise free of a direct coupling with
transmission output A. To this end a superposition gear 9 is
provided between transmission input E and transmission output A.
This superposition gear is designed as a three-shaft planetary gear
11. The three-shaft planetary gear includes a first shaft 13, a
second shaft 14, and a third shaft 15. The first shaft 13 is at
least indirectly connected in a rotationally fixed manner to the
input E of the transmission unit or is formed by same. The second
and third shafts 14, 15 are at least indirectly connected to the
input 7 and to the output 8 of the flexible drive transmission 6.
The second shaft 14 is connected to a first disk system 33 of the
flexible drive transmission 6 which, depending on the direction of
power transmission, functions as an input 7 or as an output 8',
whereas the third shaft 15 is connected to a second disk system 35
of the flexible drive transmission 6 which, depending on the
functional assignment, functions as an output 8 or as an input 7'.
The function of the individual disk systems 33, 35, i.e., the
direction of power transmission via the flexible drive transmission
6, may be changed. Therefore, in a first operating state the input
is denoted by reference numeral 7 at the first disk system 33 and
the output is denoted by reference numeral 8 at the second disk
system 35, whereas when the direction of power transmission is
changed the input at the second disk system 35 is denoted by 7' and
the output at the first disk system 33 is denoted by 8'. The first
shaft 13 of the three-shaft planetary gear 11 is formed by the
internal gear 24, the second shaft 14 is formed by the sun wheel
25, and the third shaft 15 is formed by the bridge 23. In the
illustrated case the configuration between transmission input E and
output A, in particular between transmission input E and the
internal gear 24, is coaxial. The bridge 23 is connected to the
second disk system 35 via a rotational speed/torque converter unit
or a connecting gear 39, which preferably is designed as a simple
spur gear set. The spur gear set includes a first spur gear 29 and
a second spur gear 30, the first spur gear 29 being coupled in a
rotationally fixed manner to the bridge 23 of the three-shaft
planetary gear 11. The second spur gear 30 is connected in a
rotationally fixed manner to the second disk system 35 of the
flexible drive transmission 6. An additional connecting gear 40
designed as a spur gear set which forms a gear ratio stage 20
serves as the coupling between the second shaft 14, in the form of
the sun wheel 25 of the planetary gear 11, and the first disk
system 33. In the simplest case the first disk system also includes
two spur gears, a first spur gear 37 and a second spur gear 38, the
first spur gear 37 being connected in a rotationally fixed manner
to the second shaft 14 in the form of the sun wheel 25 of the
planetary gear 11, and intermeshing with the spur gear 38 which is
connected in a rotationally fixed manner to the first disk system
33. The design of the two connecting gears 39, 40 as spur gear sets
in the form described represents one possible design. Other designs
are also possible. However, this design is characterized by the
lowest number of components. The two connecting gears 39, 40 in
each case form a gear ratio stage 19, 20, respectively, from the
planetary gear 11 to the individual disk systems 33 or 35 of the
flexible drive transmission 6. The two gear ratio stages 19, 20
have a fixed gear ratio. Both have the same number of mutually
engaged spur gears, i.e., depending on the selection, either an
even number or an odd number. Thus, by use of these gear ratio
stages either the same rotational direction or a reversed
rotational direction relative to the shafts of the planetary gear
11 coupled thereto may be achieved. The superposition gear 9 and
the inputs of connecting gears 39, 40 coupled thereto have a
coaxial configuration. The design is implemented by use of passages
and hollow shafts.
[0050] The planetary gear 11 is designed in such a way that it has
planet wheels 47 and 48 which in each case intermesh in pairs
between the sun wheel 25 and the internal gear 24, in each case
planet wheels 47.1 and 48.1 intermeshing and forming a planet wheel
pair 46.1. Depending on the number n of planet wheel pairs
selected, these are denoted by reference numeral 46.n. The first
planet wheel, for example 47.1, intermeshes with the planet wheel
48.1 of the planet wheel pair 46.1 and with the sun wheel 18,
whereas the second planet wheel 48.1 of the planet wheel pair 46.1
intermeshes with the first planet wheel 47.1 and with the internal
gear 24. These pairs of intermeshing planet wheels 47.n and 48.n,
forming the planet wheel pair 46.n where n>1, preferably have
identical designs; i.e., a planet wheel pair 46.n preferably has a
gear ratio of 1:1. Other gear ratios are also possible, for example
1:0.8 to 1:1.2. The design of the provided gear ratio stages 19, 20
between the planetary gear 11 and the continuously variable
transmission is provided corresponding to the maximum allowable
rotational speed at the CVT. For the planetary gear 11, gear ratios
between the internal gear 24 and the sun wheel 25 are selected to
be 1:2.5 to 1:3.5, preferably 1:3, as a function of the spread of
the continuously variable transmission.
[0051] The third shaft 15 in the form of the bridge 23 may also be
at least indirectly connected to transmission output A. Thus, when
power is transmitted via the flexible drive transmission 6 from
transmission input E via the planetary gear 11 and the connecting
gear 40 to the flexible drive transmission 6, from disk system 33
to disk system 35 via the bridge a coupling is provided with
transmission output A via the connecting gear 39. When power is
transmitted via the flexible drive transmission 6 in the direction
from disk system 35 to the first disk system 33, either a coupling
occurs with transmission output A via the planetary gear 11, in
particular from the sun wheel 25 on the bridge 23, or, when the
rotational speeds are equal, a direct coupling is provided via the
spur gear 37 of the connecting gear 20 at least indirectly to
output A via the second superposition gear 10, which is designed as
a planetary gear 12. The planetary gear 12 is likewise designed as
a three-shaft planetary gear including a first shaft 16, a second
shaft 17, and a third shaft 18. These shafts may be at least
indirectly connected via shiftable clutches 21 and 22 to the first
superposition gear 9 in the form of the planetary gear 11, forming
a four-shaft planetary gear. The first shaft 16 is formed by the
bridge 26, the second shaft 17 is formed by the internal gear 28,
and the third shaft 18 is formed by the sun wheel 27.
[0052] The second shaft 17 is connected in a rotationally fixed
manner to output A. The second shaft 17 is also connected via the
clutch unit 22 to the continuously variable transmission 5 via the
connecting gear 40, and is also connected to the second shaft of
the first planetary gear 11. The first shaft 16 of the second
superposition gear 10 may be connected in a rotationally fixed
manner to the third shaft 15 of the planetary gear 11, in
particular to the bridge 23, via the additional clutch 21. The
shiftable clutch 21 is used to couple the planetary gear 12 to the
first planet wheel set 11, in this case a four-shaft planetary gear
being formed from the two three-shaft planetary gears 11, 12 when
the clutch 21 is engaged.
[0053] The shiftable clutch 22 is provided between the second shaft
14 of the first planetary gear 11 and the second shaft 17, which is
designed as an internal gear 28 of the planetary gear 12. As the
result of the coupling of the second shaft 14 of the first
planetary gear 11 to the third shaft 18 in the form of the sun
wheel 27 of the planetary gear 12, this shiftable clutch 22 allows
a rigid coupling between the sun wheel 27 and the internal gear 28
of the planetary gear 12, i.e., between the second and third
shafts, and thus enables the connection of the second shaft 14 of
the first planetary gear 11 to the internal gear 28 which is
coupled in a rotationally fixed manner to transmission output A. In
this case the output is provided, in a manner of speaking, directly
by the second shaft 14 on transmission output A without further
step-up.
[0054] Both shiftable clutches 21 and 22 may be selectively
actuated. The shiftable clutch 22 is used for the coupling between
transmission output A and the second shaft 14 of the first
planetary gear 11, and the additional clutch 21 provides the
rotationally fixed connection of the bridge 15, via the second
planetary gear 12, to transmission output A. The shifting is
optionally performed as needed. When the individual elements of the
planetary gear are synchronous, both elements are preferably
actuated in an overlapping manner so that the second and third
shafts 14 and 15 operate synchronously. The shiftable clutches may
be friction clutches. However, synchronously shiftable clutches are
preferably used.
[0055] The continuously variable transmission 5, as previously
described, is designed as a flexible drive transmission including
two disk systems, a first disk system 33 and a second disk system
35, which are connected to one another in a force-transmitting
manner via a traction way 34. Depending on the direction of power
transmission, the first disk system 33 functions as an input 7, and
disk system 35 functions as an output 8, or, when the function of
the input is assigned to the third shaft 15, functions as an output
8'. In the latter case the respective other disk system, in this
instance disk system 35, forms input 7'. In a first operating range
the clutch 21 is engaged. In this case there is a connection
between transmission input E and the first shaft 13 in the form of
the internal gear 24 of the planetary gear 11. The power flow is
transmitted via the first shaft 13 of the planetary gear 11 to the
second shaft 14 in the form of the sun wheel 25. Disk system 33 is
driven via the connecting gear 40 and the gear ratio stage 20
formed thereby, and disk system 35 is driven via the traction way
34. The effect via the gear ratio stage 19, which is formed by the
connecting gear 39 or its output in the form of the spur gear 29
connected in a rotationally fixed manner to the bridge 23 of the
planetary gear 11, results on account of the coupling via the
clutch 21 to the second planetary gear 12, in particular the gear
ratio, present at that location, of the rotational speed at output
A. The rotational speed may be varied corresponding to the
displacement at the individual disk systems 33 and 35. The input of
the continuously variable transmission 5 is thus no longer directly
coupled to the rotational speed of the drive motor, i.e., the
rotational speed at transmission input E. The rotational speed at
transmission output A may be changed by controlling the
continuously variable transmission 5 and also via the planetary
gear 12. The direction of power transmission changes when the
clutch is changed from disk system 33 to 35, or from 35 to 33, or
from 7 to 8, or from 8 to 7.
[0056] When there is synchronism between the internal gear 28 and
the sun wheel 27, and thus between the shafts connected thereto,
clutch 21 is disengaged and clutch 22 is engaged. In this position
as well, the entire operating range of the CVT may be traversed
twice, i.e., depending on the position of the disks of disk systems
33 and 35 relative to one another and the direction of power
transmission from 33 to 35 or from 35 to 33.
[0057] The coupling between the individual disk systems 33 and 35
of the continuously variable transmission 5 and the superposition
gear 9 in the form of the planetary gear 11 results, as previously
described, via the connecting gear 39, 40 in the form of gear ratio
stages 19, 20, which are formed by rotational speed/torque
converter units. In the design as a positive-fit flexible drive
transmission 6, the way 31 for controlling the gear ratios at disk
systems 33, 35 includes a way for displacing the two disk systems
33 and 35, whereby the distance between the disks of a disk system
may be varied by way of the drive force at the disks, and this
variable is used as a direct control variable or a variable which
at least indirectly characterizes same, and a corresponding
actuating device for varying the drive force, i.e., actuating
devices for impinging on the individual disks or displacing same.
The disks may be operated electrohydraulically, for example, or by
other ways. A corresponding actuating device may be associated with
either one disk system 33, 35, or preferably with both. In the
first-referenced option, corresponding ways are provided for
automatic setting or adaptation. Another possibility lies in
actuating both disk systems 33, 35. With regard to the specific
design itself, numerous possibilities are well known from the prior
art which will not be addressed here in detail. This also applies
to the actuation methods themselves, as well as specification of
the control, regulation, and/or reference variables for operation
of the flexible drive transmission 6, as well as incorporation of
same into existing drive designs. There are also numerous
possibilities for the design of the continuously variable
transmission 5. The coupling of the two disk systems 33 and 35 and
the transmission of force occur in each case via traction way 34,
for example in the form of belts, chains, or a push belt, in such
cases the design of the disks with regard to the positive-fit and
form-fit transmission of force being correspondingly adapted, and
the disk systems in a manner of speaking assuming the function of
carrier elements.
[0058] As previously described, when the clutch 21 is engaged power
is transmitted from transmission input E to the planetary gear 11,
via the sun wheel 25 to the connecting gear 40, and from there to
the flexible drive transmission 6, the connecting gear 39, and via
the reaction thereof to the planetary gear 11, in particular the
bridge 23, and via the planetary gear 12 to transmission output A.
When the disk system is displaced so as to change the direction of
power transmission from the second to the first disk system for
transmitting power from the first to the second disk system, the
power is transmitted, in a manner of speaking, from transmission
input E, to the bridge 23 via the connecting gear 39 to disk system
35, and from there via the traction way 34 to disk system 33, the
connecting gear 40, and then, depending on the shifting of clutches
21 or 22, via the planetary gear 12 to transmission output A. The
entire operating range of the continuously variable transmission is
thus traversed twice in a manner of speaking, each time in
different directions. Depending on the clutch 21 or 22 that is
shifted, in each case in the individual operating ranges which are
characterized by the shifting of a clutch, the power transmission
ranges traverse the flexible drive transmission in both directions,
whereby operation above the zero level is possible.
[0059] The connecting gear 19, 20 is designed as follows, for
example:
[0060] for 19:1:1 to 0.5:1
[0061] for 20:1:2 to 1:1.
[0062] According to one particularly advantageous embodiment, means
41 are provided for adapting the rotational speed of the traction
way 34 to the rotational speed of transmission input E, i.e., for
slip-free coupling of the traction way to the rotational speed of
the transmission input. These ways include a transmitting element
42 which is at least indirectly coupled to transmission input E and
is in a positive-fit mechanical linkage with the traction way 34.
The traction way 34 is provided at the outer periphery 43 with
profiling 44 which engages with correspondingly designed profiling
45 at the outer periphery 49 of the transmitting element 42.
Another possibility is to design the traction way 34 as a chain or
as a combination of a belt and chain, in which case the
transmitting element is designed as a sprocket wheel; i.e., the
design consistently results from the unchanged positioning of the
transmitting element relative to the traction way 34. According to
a first approach, adjustments to the traction way upon changes in
the operating radius when the disks of the continuously variable
transmission are displaced, as well as synchronous adaptation of
the rotational speed of the traction way to the rotational speed of
the transmission input, are compensated for by use of a clamping
device, in particular a tensioning roller. The tensioning roller
may be swiveled relative to the traction way and stationarily
supported. The transmitting element is at least indirectly coupled
to the transmission input. This means that the transmitting element
is either coupled in a rotationally fixed manner to transmission
input E or is coupled thereto via additional transmitting elements.
To ensure rotation of the transmitting element in the same
rotational direction as the operating direction of the traction
way, the traction way is either directly coupled in a rotationally
fixed manner to the drive shaft or transmission input, or is
coupled via additional transmitting elements such as a spur gear
set, in which case the number of intermeshing transmitting elements
is odd.
[0063] While this invention has been described with respect to at
least one embodiment, the present invention can be further modified
within the spirit and scope of this disclosure. This application is
therefore intended to cover any variations, uses, or adaptations of
the invention using its general principles. Further, this
application is intended to cover such departures from the present
disclosure as come within known or customary practice in the art to
which this invention pertains and which fall within the limits of
the appended claims.
LIST OF REFERENCE NUMERALS
[0064] 1 Transmission unit [0065] 2 Multirange transmission [0066]
3 First power branch [0067] 4 Second power branch [0068] 5
Continuously variable transmission [0069] 6 Flexible drive
transmission [0070] 7 Input of the continuously variable
transmission [0071] 8 Output of the continuously variable
transmission [0072] 9 First superposition gear [0073] 10 Second
superposition gear [0074] 11 Three-shaft planetary gear [0075] 12
Three-shaft planetary gear [0076] 13 First shaft [0077] 14 Second
shaft [0078] 15 Third shaft [0079] 16 First shaft [0080] 17 Second
shaft [0081] 18 Third shaft [0082] 19 Gear ratio stage [0083] 20
Gear ratio stage [0084] 21 First shiftable clutch [0085] 22 Second
shiftable clutch [0086] 23 Bridge of planetary gear 11 [0087] 24
Internal gear of planetary gear 11 [0088] 25 Sun wheel of planetary
gear 11 [0089] 26 Bridge of planetary gear 12 [0090] 27 Sun wheel
of planetary gear 12 [0091] 28 Internal gear of planetary gear 12
[0092] 29 First spur gear [0093] 30 Second spur gear [0094] 31 Way
for controlling the gear ratio [0095] 32 Shaft [0096] 33 First disk
system [0097] 34 Traction way [0098] 35 Second disk system [0099]
36 Spur gear set [0100] 37 First spur gear [0101] 38 Second spur
gear [0102] 39 Connecting gear [0103] 40 Connecting gear [0104] 41
Way [0105] 42 Transmitting element [0106] 43 Outer peripheral
traction way [0107] 44 Profiling [0108] 45 Profiling [0109] 46.1,
46.n Planet wheel pair [0110] 47 Planet wheel [0111] 48 Planet
wheel [0112] 49 Outer peripheral transmitting element [0113] 50
Intermediate gear stage [0114] E Input [0115] A Output
* * * * *