U.S. patent application number 10/021310 was filed with the patent office on 2002-08-29 for power train for a motor vehicle.
This patent application is currently assigned to LuK Lamellen und Kupplungsbau Beteiligungs KG. Invention is credited to Man, Laszlo, Muller, Bruno, Reik, Wolfgang.
Application Number | 20020117860 10/021310 |
Document ID | / |
Family ID | 27438859 |
Filed Date | 2002-08-29 |
United States Patent
Application |
20020117860 |
Kind Code |
A1 |
Man, Laszlo ; et
al. |
August 29, 2002 |
Power train for a motor vehicle
Abstract
A power train for a motor vehicle includes a combustion engine,
a clutch or other torque-coupling device, a transmission, and an
electro-mechanical energy converter that is operable at least as a
motor and as a generator. The electro-mechanical energy converter
is coupled to the output shaft of the combustion engine through a
torque transfer device with at least two rpm ratios that
automatically set themselves according to whether the vehicle is
operating in a start-up mode or in a driving mode.
Inventors: |
Man, Laszlo; (Ottersweier,
DE) ; Reik, Wolfgang; (Buhl, DE) ; Muller,
Bruno; (Buhl, DE) |
Correspondence
Address: |
DARBY & DARBY P.C.
805 Third Avenue
New York
NY
10022
US
|
Assignee: |
LuK Lamellen und Kupplungsbau
Beteiligungs KG
|
Family ID: |
27438859 |
Appl. No.: |
10/021310 |
Filed: |
October 22, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10021310 |
Oct 22, 2001 |
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09564361 |
Jun 22, 2001 |
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09564361 |
Jun 22, 2001 |
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PCT/DE99/02833 |
Sep 2, 1999 |
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Current U.S.
Class: |
290/46 ;
180/65.21; 180/65.25; 180/65.26; 475/5; 903/903; 903/910; 903/914;
903/918; 903/946; 903/951 |
Current CPC
Class: |
F16H 61/66 20130101;
B60K 2006/268 20130101; B60W 10/02 20130101; B60K 6/365 20130101;
B60K 6/485 20130101; B60W 20/00 20130101; B60K 6/48 20130101; B60K
6/543 20130101; Y10S 903/91 20130101; B60K 6/445 20130101; Y02T
10/62 20130101; B60W 20/10 20130101; F02N 11/04 20130101; F16H 3/54
20130101; B60K 6/40 20130101; B60K 6/405 20130101; B60K 6/387
20130101 |
Class at
Publication: |
290/46 ; 475/5;
180/65.4 |
International
Class: |
H02K 023/52; B60K
006/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 9, 1998 |
DE |
198 41 140.5 |
Mar 25, 1999 |
DE |
199 13 493.6 |
Apr 1, 1999 |
DE |
199 15 166.0 |
Apr 15, 1999 |
DE |
199 16 936.5 |
Claims
What is claimed is:
1. A power train for a motor vehicle, said power train comprising a
combustion engine with a driving shaft turning at a first rpm rate,
at least one torque-coupling device, a transmission with a
transmission input shaft, and at least one electro-mechanical
energy converter with an energy-converter shaft turning at a second
rpm rate, said electro-mechanical energy converter being operable
at least as a motor and as a generator and having an interactive
rotary connection to the driving shaft; wherein the interactive
rotary connection has at least two rpm ratios defined as quotients
of the first rpm rate divided by the second rpm rate, and wherein
the at least two rpm ratios automatically set themselves according
to which of at least two operating modes the electro-mechanical
energy converter is working in, said at least two operating modes
comprising a start-up mode and a driving mode.
2. The power train of claim 1, wherein the driving shaft has a rear
end facing towards the transmission and the interactive rotary
connection is arranged at said rear end, and wherein further the
transmission input shaft can be coupled to and uncoupled from the
driving shaft by means of the at least one torque-coupling
device.
3. The power train of claim 1, wherein the driving shaft has a
front end facing away from the transmission and the interactive
rotary connection is arranged at said front end.
4. The power train of claim 1, wherein the driving shaft has a
first rotary axis and the electro-mechanical energy converter has a
second rotary axis, and wherein said first and second rotary axes
are substantially parallel to each other.
5. The power train of claim 1, wherein the interactive rotary
connection comprises at least a pair of sheaves and an endless-loop
device coupling the sheaves to each other by frictional
contact.
6. The power train of claim 5, wherein each sheave comprises a
belt-drive pulley and the endless-loop device comprises a belt.
7. The power train of claim 5, wherein each sheave comprises a pair
of conical discs and the endless-loop device comprises a chain.
8. The power train of claim 7, wherein the conical discs of each
pair can be set at a variable axial distance from each other,
thereby varying the radius of a contact circle where the chain is
held between the conical discs, so that any rpm ratio within a
continuous range can be set between the pairs of discs.
9. The power train of claim 1, wherein the interactive rotary
connection comprises at least one gear pair.
10. The power train of claim 1, wherein the electro-mechanical
energy converter serves as a starter motor for the combustion
engine.
11. The power train of claim 1, wherein the electro-mechanical
energy converter is used to propel the motor vehicle.
12. The power train of claim 1, wherein during a start-up phase of
the combustion engine the second rpm rate is higher than the first
rpm rate.
13. The power train of claim 12, wherein the rpm ratio for the
start-up phase is between 2:3 and 1:10.
14. The power train of claim 1, wherein under a first mode of the
at least two operating modes the torque flows from the
electro-mechanical energy converter to the combustion engine, and
under a second mode of the at least two operating modes the torque
flows from the combustion engine to the electro-mechanical energy
converter.
15. The power train of claim 14, wherein the rpm ratio for the
first mode is smaller than the rpm ratio for the second mode.
16. The power train of claim 15, wherein the rpm ratio or the
second mode is between 2:1 and 1:2 and is used to run the
electro-mechanical energy converter in a generator mode.
17. The power train of claim 14, wherein the interactive rotary
connection comprises at least one rotary transfer device arranged
between the electro-mechanical energy converter and the combustion
engine.
18. The power train of claim 17, wherein the at least one rotary
transfer device comprises a planetary gear mechanism with at least
one ring gear, at least one sun gear, and at least one planet
carrier with at least one planet gear.
19. The power train of claim 17, wherein the at least one rotary
transfer device comprises a gear mechanism with stationary gear
shafts and at least two gear pairs.
20. The power train of claim 17, wherein the at least one rotary
transfer device comprises at least two clutches for engaging and
disengaging the different rpm ratios.
21. The power train of claim 20, wherein at least one of the at
least two clutches is an overrunning clutch.
22. The power train of claim 21, wherein at least two of the at
least two clutches are overrunning clutches.
23. The power train of claim 20, wherein at least one of the at
least two clutches is a centrifugal clutch.
24. The power train of claim 20, wherein at least one of the at
least two clutches is an electromagnetic clutch.
25. The power train of claim 17, wherein the interactive rotary
connection further comprises at least one fixed-ratio rotary
transfer stage.
26. The power train of claim 25, wherein the fixed ratio of the
first divided by the second rpm rate is between 3:2 and 5:1.
27. The power train of claim 25, wherein the fixed-ratio rotary
transfer stage comprises a belt drive with pulleys of different
diameters.
28. The power train of claim 25, wherein the fixed-ratio transfer
stage comprises a gear pair.
29. The power train of claim 18, wherein the rotary transfer device
comprises a housing and the at least one ring gear is connected and
thereby rotationally coupled to the housing.
30. The power train of claim 17, wherein the at least one rotary
transfer device further comprises a first clutch located in a first
torque flow path that is operative under the first mode, and a
second clutch located in a second torque flow path that is
operative under the second mode, and wherein the first clutch is
engaged in the first mode and disengaged in the second mode, while
the second clutch is engaged in the second mode and disengaged in
the first mode.
31. The power train of claim 30, wherein the first clutch and the
second clutch are overrunning clutches.
32. The power train of claim 30, wherein the at least one rotary
transfer device comprises a planetary gear mechanism with a ring
gear, a sun gear, and a planet carrier with at least one planet
gear, wherein under the first mode the electro-mechanical energy
converter drives the sun gear which, in turn, drives the planet
carrier through the at least one planet gear, and the planet
carrier drives the combustion engine; and wherein under the second
mode, the combustion engine drives the planet carrier with the at
least one planet gear which, in turn, drives the electro-mechanical
energy converter through the sun gear.
33. The power train of claim 30, wherein the at least one rotary
transfer device comprises a first gear pair and a second gear pair,
wherein under the first mode the electro-mechanical energy
converter drives the combustion engine through the first clutch and
the first gear pair; and wherein under the second mode, the
combustion engine drives the electro-mechanical energy converter
through the second clutch and the second gear pair.
34. The power train of claim 30, wherein the rotary transfer device
has first transfer elements that determine the first rpm ratio and
wherein the first clutch is placed in the torque flow path at one
of an upstream location and a downstream location relative to the
first transfer elements.
35. The power train of claim 30, wherein the rotary transfer device
has second transfer elements that determine the second rpm ratio
and wherein the second clutch is placed in the torque flow path at
one of an upstream location and a downstream location relative to
the second transfer elements.
36. The power train of claim 17, wherein the rotary transfer device
is arranged on one of the driving shaft and the transmission input
shaft.
37. The power train of claim 17, wherein the electro-mechanical
energy converter comprises a rotor and a stator, and the rotary
transfer device is arranged radially inside the rotor.
38. The power train of claim 17, wherein the interactive rotary
connection comprises a belt drive with a belt, and a first pulley
connected to the combustion engine, and a second pulley connected
to the electro-mechanical energy converter.
39. The power train of claim 38, wherein the rotary transfer device
is arranged radially inside one of the first pulley and the second
pulley.
40. The power train of claim 17, wherein the transmission comprises
the rotary transfer device.
41. The power train of claim 1, wherein the interactive rotary
connection comprises a rotary vibration damping device with
energy-storing elements allowing the driving shaft and the energy
converter shaft to rotate in relation to each other within a
limited range against an opposing torque of the energy-storing
elements.
42. The power train of claim 1, wherein the interactive rotary
connection comprises a rotary shock/vibration absorbing device.
43. The power train of claim 37, wherein at least one of a rotary
vibration damping device and a rotary shock/vibration absorbing
device is arranged radially inside one of a belt-drive pulley and
the rotor.
44. The power train of claim 1, wherein at least one of a rotary
vibration damping device and a rotary shock/vibration absorbing
device is arranged on one of the driving shaft and the
energy-converter shaft.
45. The power train of claim 18, wherein the ring gear, the planet
gears, and the sun gear comprise a helical tooth profile; wherein
under the first mode, the helical tooth profile pushes the ring
gear in a first axial direction where the ring gear becomes locked
to a non-rotating component; and wherein under the second mode, the
helical tooth profile pushes the ring gear in a second axial
direction where the ring gear becomes locked to the planet
carrier.
46. The power train of claim 18, wherein the rotary transfer device
has a ratio-locking means which, at rpm rates exceeding those
required for the start-up mode, prevents the rotary transfer device
from shifting out of a first rpm ratio that is normally reserved
for the start-up mode.
47. The power train of claim 46, wherein the ratio-locking means
comprises at least one centrifugal body arranged at an external
circumference of the planet carrier, and wherein a centrifugal
force drives the centrifugal body into form-locking engagement with
a recess at an internal circumference of the ring gear.
48. The power train of claim 47, wherein the at least one
centrifugal body has a spherical shape.
49. The power train of claim 45, wherein the ring gear has axially
engaging coupler means for coupling the ring gear to one of the
non-rotating component and the planet carrier.
50. The power train of claim 49, wherein the coupler means comprise
at least one of a Hirth coupler, a dog clutch, and a friction
clutch.
51. The power train of claim 17, wherein the rotary transfer device
has a housing and the combustion engine has an engine housing, and
wherein the housing is fixedly attached to the engine housing.
52. The power train of claim 17, wherein the interactive rotary
connection further comprises a belt drive with a belt and the
rotary transfer device comprises a housing.
53. The power train of claim 52, wherein the housing comprises a
lever arm carrying a belt-tensioning means, the housing being
rotatably supported on one of the driving shaft and the
energy-converter shaft, and wherein the housing is constrained to a
rotary range of less than a full turn by the belt-tensioning means
bearing against the belt.
54. The power train of claim 53, wherein the belt-tensioning means
is set to provide a base amount of belt tension, and wherein a
torque-dependent amount of belt tension is superimposed on said
base amount.
55. The power train of claim 53, wherein said rotatable support
comprises a bearing, and wherein said bearing is arranged in a
plane defined by the belt.
56. The power train of claim 52, wherein the interactive rotary
connection further comprises a belt pulley rotatably supported by a
belt-pulley bearing on one of the driving shaft and the
energy-converter shaft, and wherein said belt-pulley bearing is
arranged in a plane defined by the belt.
57. The power train of claim 52; wherein the housing is rotatably
supported on the driving shaft; wherein the housing, in turn,
rotatably supports a first pulley on a first pulley shaft that is
offset from the driving shaft; wherein the rotary transfer device
is connected to the first pulley by way of a first gear that is
rotationally constrained to the first pulley; and wherein the first
pulley is connected by way of the belt to a second pulley mounted
on the energy-converter shaft.
58. The power train of claim 52; wherein the housing is rotatably
supported on the energy-converter shaft; wherein the housing, in
turn, rotatably supports a second pulley on a second pulley shaft
that is offset from the energy-converter shaft; wherein the rotary
transfer device is connected to the second pulley by way of a
second gear that is rotationally constrained to the second pulley;
and wherein the second pulley is connected by way of the belt to a
first pulley mounted on the energy-converter shaft.
59. The power train of claim 52; wherein the rotary transfer device
comprises a planetary gear mechanism with a sun gear, a planet
carrier with at least one planet gear, and a ring gear.
60. The power train of claim 59; wherein the sun gear, the at least
one planet gear, and the ring gear have helical tooth profiles;
wherein the ring gear is axially movable to one side into
engagement with the housing and to an opposite side into engagement
with the planet carrier; and wherein said movement between the one
side and the opposite side serves to shift the rotary transfer
device between the at least two rpm ratios.
61. The power train of claim 52; wherein the housing is rotatably
supported on the driving shaft; wherein the housing, in turn,
rotatably supports a first pulley on a first pulley shaft that is
offset from the driving shaft; wherein the rotary transfer device
comprises a spur gear mechanism with two gear pairs providing the
at least two rpm ratios, each gear pair having a fixed gear solidly
connected to the first pulley shaft and an overrunning gear
supported on the driving shaft through an overrunning clutch; and
wherein the overrunning clutches have opposite overrunning
directions.
62. The power train of claim 52; wherein the housing is rotatably
supported on the energy converter shaft; wherein the housing, in
turn, rotatably supports a second pulley on a second pulley shaft
that is offset from the energy converter shaft; wherein the rotary
transfer device comprises a spur gear mechanism with two gear pairs
providing the at least two rpm ratios, each gear pair having a
fixed gear solidly connected to the second pulley shaft and an
overrunning gear supported on the energy converter shaft through an
overrunning clutch; and wherein the overrunning clutches have
opposite overrunning directions.
63. The power train of claim 52; wherein the housing is rotatably
supported on a first shaft comprising one of the driving shaft and
the energy converter shaft; wherein the housing, in turn, rotatably
supports a pulley on a pulley shaft: and wherein the pulley shaft
is offset from the first shaft by a distance d which, for a given
slack of the belt, is large enough to prevent the pulley shaft from
swiveling by a full turn around the first shaft.
64. The power train of claim 63; wherein the distance d is between
1 centimeter and 20 centimeters.
65. The power train of claim 52; wherein the rotary transfer device
comprises two belt drives providing the at least two rpm ratios,
each belt drive having a fixed pulley solidly connected to one of
the driving shaft and the energy converter shaft and an overrunning
pulley connected through an overrunning clutch to the other of the
driving shaft and the energy converter shaft; and wherein the
overrunning clutches have opposite overrunning directions.
66. The power train of claim 37; wherein the driving shaft has a
front end facing away from the transmission and the
electro-mechanical energy converter is arranged coaxially with the
driving shaft at said front end; and wherein the rotary transfer
device comprises an output element connected to the driving shaft
and an input element connected to the rotor.
67. The power train of claim 18, wherein the electro-mechanical
energy converter has a rotor, and wherein the planet carrier has a
first torque-transmitting connection to the driving shaft and the
sun gear has a second torque-transmitting connection to the rotor.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a motor vehicle power train
including a drive source such as a combustion engine with a driving
shaft, a driven unit with a driven shaft such as a transmission
with a transmission input shaft, as well as at least one
electro-mechanical energy converter interacting with the power
train, and at least one clutch that is arranged in the torque flow
path between the driving shaft and the driven shaft and serves to
couple and uncouple the torque flow between the drive source and
the driven unit.
[0002] Arrangements of this kind are known from the German
laid-open application DE-OS 32 30 121 as hybrid drives with an
electric motor and a combustion engine, or from the German patent
DE-PS 41 12 215 as combustion engines with a starter-generator.
[0003] Depending on the specific layout, the electro-mechanical
energy converter may be arranged either coaxially surrounding the
rotational axis of the combustion engine--as known for example from
the German laid-open application DE-OS 33 35 923--, or aligned
along a separate axis of rotation parallel to the rotational axis
of the combustion engine, as known from the French laid-open
application FR-OS 81 19324.
[0004] When using the electro-mechanical energy converter to start
the combustion engine, in order to make better use of the limited
amount of available torque, the interactive connection to the power
train, e.g., a belt-, friction-, or gear drive, is usually run at a
transfer ratio where the electro-mechanical energy converter turns
faster than the drive source, the latter being for example a
combustion engine. As soon as the combustion engine is running and
the electro-mechanical energy converter is operated in the
generator mode, it is advantageous to operate the
electro-mechanical energy converter at a transfer ratio that is
optimized for the generator mode in order to increase the degree of
efficiency, which requires the use of a ratio-changing rotary
transfer mechanism.
[0005] A proposed arrangement according to the German patent DE-PS
41 12 215 includes a planetary gear mechanism in which the change
of transfer ratios is controlled from the outside by way of a
clutch that is actuated by an additionally required actuator motor.
The additional transducer and control means required with this
solution lead to an increase in weight as well as cost.
OBJECT OF THE INVENTION
[0006] The present invention therefore has the objective of
improving a power train of the kind described above by providing an
interactive connection between the electro-mechanical energy
converter and the combustion engine with a means of changing the
transfer ratio that is more cost-effective and easier to handle,
ensures a longer operating life of the interactive connection, and
can easily be installed on the housing of the combustion engine, if
possible without requiring a modification of the engine
housing.
SUMMARY OF THE INVENTION
[0007] The present invention solves the task just stated by
proposing a motor vehicle power train that includes a drive source
such as a combustion engine with a driving shaft as well as at
least one electro-mechanical energy converter that is interactively
connected with the driving shaft and works at least as a motor and
as a generator. The interactive connection between the
electro-mechanical energy converter and the driving shaft has at
least two transfer ratios that set themselves automatically
according to which operating mode the electro-mechanical energy
converter is working in. The selection of operating modes includes
at least a start-up mode and a driving mode.
[0008] The electro-mechanical energy converter according to the
inventive concept can be designed as a synchronous, asynchronous,
reluctance-based, or other type of machine, and it can be arranged
advantageously on a shaft other than the driving shaft. In
particular, the electro-mechanical energy converter can be arranged
on a shaft that runs parallel to the output shaft of the drive
source, which can be a combustion engine, turbine, or the like. It
may be advantageous to arrange the interactive connection between
the electro-mechanical energy converter and the driving shaft at a
location between the combustion engine and the driven unit, or at
the opposite end of the driving shaft which normally drives
auxiliary devices. It may also be advantageous to use a single belt
to drive several auxiliary devices including the electro-mechanical
energy converter.
[0009] The interactive connection can be formed by a pair of
pulleys that are coupled to each other through the frictional
contact with an endless-loop element. The pulleys can be
belt-transmission pulleys of the known kind and the endless-loop
element can be a belt. As a particularly advantageous alternative,
especially for transmitting a torque of large magnitude, one could
use pairs of conical discs, where the endless-loop device takes the
form of a chain providing the frictional torque transfer between
the cone pulleys. The interactive connection could further be
designed as at least one pair of meshing gears or friction wheels.
It is advantageous to provide for each transfer ratio a separate
pair of gears or a separate pair of pulleys with its own
endless-loop element.
[0010] In an appropriate application of a power train according to
the invention, the electro-mechanical energy converter is used at
least as a starter motor, but it could also be advantageously
employed for other uses. In this case, the electro-mechanical
energy converter can be designed with an appropriate performance
characteristic, so that it can be used not only as a generator and
starter motor, but can also deliver torque to the driven unit,
possibly to the extent of propelling the vehicle with the
electro-mechanical energy converter alone.
[0011] The driven unit may be, e.g., a speed-changing transmission
that can be uncoupled from the combustion engine by means of at
least one clutch. It is advantageous if the electro-mechanical
energy converter can be interactively connected to the combustion
engine while being uncoupled from the driven unit, with the
possibility that the electro-mechanical energy converter can also
be connected to the speed-changing transmission while the
combustion engine may be uncoupled from the electro-mechanical
energy converter and the transmission. Arrangements of this kind
suggest themselves particularly if, to optimize the degree of
efficiency, the electro-mechanical energy converter and/or its
rotary transfer device are to be spatially and/or functionally
accommodated inside the transmission converter. In this case, the
engine is started preferably with the speed-changing transmission
in a neutral condition. The electro-mechanical energy converter may
be arranged so that it coaxially surrounds the transmission input
shaft, or it may be arranged on a separate shaft of its own that is
interactively connected to the transmission input shaft. Further
references made herein to an interactive connection between the
combustion engine and the electro-mechanical energy converter will
implicitly include the interactive connection between the driven
unit and the electro-mechanical energy converter through the
transmission input shaft.
[0012] It may further be advantageous if the electro-mechanical
energy converter is arranged between two shiftable clutches, so
that the electro-mechanical energy converter can be uncoupled from
the engine as well as from the driven unit, in order to make use of
the inertial momentum of the freely rotating electro-mechanical
energy converter for generating electrical energy and/or to build
up a rotary momentum for starting the engine, in which case the
electro-mechanical energy converter can be coupled to an inertial
mass that is arranged on the driving shaft, e.g., a flywheel.
[0013] It is advantageous according to the inventive concept, if
the interactive connection between the driving shaft and the
electro-mechanical energy converter includes a rotary transfer
device that allows the working rpm-rates of the electro-mechanical
energy converter to be better adapted to the degree of efficiency
that is achievable in the different operating modes, and if the
switch-over from one transfer ratio of the rotary transfer device
to another is controlled automatically by the rotary transfer
device itself. An arrangement with many different transfer ratios
may be advantageous, but there may also be a particular advantage
in a simplified embodiment with only two transfer ratios because of
the lower complexity. If the electro-mechanical energy converter is
used as a starter/generator, a first operating mode or starting
mode is to crank up the combustion engine, and a second operating
mode or driving mode is to generate electrical energy. Accordingly,
a first transfer ratio is provided for the starting mode, and a
second transfer ratio is provided for the driving mode. In the
first transfer ratio, the rpm-rate of the electro-mechanical energy
converter is stepped down to a lower rpm-rate of the engine shaft,
resulting in an increased torque for starting the engine. The
second transfer ratio, used in the driving mode, is designed so
that the rpm-ratio between the electro-mechanical energy converter
and the driving shaft is between 1:2 and 2:1. It is advantageous to
design the interactive connection so that there is no change in
rpm-rate in the driving mode. The first transfer ratio is selected
with special preference in a range between 3:2 and 7:1. It may in
some cases be advantageous to provide a transmission stage with a
constant ratio of, e.g., between 3:2 and 5:1 by which the
engine-rpm rate is smaller in relation to the rpm-rate of the
electro-mechanical energy converter. This constant-ratio stage may
be superimposed on the two transfer ratios.
[0014] The different transfer ratios can advantageously be provided
by torque-transfer devices of all kinds, including standing
transmissions and orbiting transmissions. The interactive
connection can be constituted by belt drives, gear pairs,
friction-wheel pairs, chain drives and the like. In the case of a
standing transmission, the interactive connection is preferably
made up of at least one gear pair.
[0015] The setting and changing of the transfer ratio is controlled
through a combination of clutches and freewheeling devices. The
latter will also be referred to herein as freewheeling clutches,
freewheeling clutch bearings, or overrunning clutches. The clutches
and freewheeling devices serve to either open or lock certain gear
combinations or torque-flow paths in the rotary transfer device.
The clutches which, depending on their arrangement, become engaged
or disengaged as the rpm rate increases, are not actuated
externally, but can be coupled and uncoupled by centrifugal forces.
Another advantageous embodiment uses an electromagnetic clutch that
is controlled by rpm-dependent electrical signals from the
starter/generator. Thus, it is possible to switch between two
different transfer ratios, e.g., with a combination of two
overrunning clutches, or with one clutch and one overrunning
clutch, or with two clutches.
[0016] In particular, a rotary transfer device can adapt its
transmission ratio depending on the direction in which the torque
acts on the transfer device, i.e., depending on whether the torque
comes from the electro-mechanical energy converter (starter mode)
or from the combustion engine (driving mode). This can be achieved
through a design where, e.g., the overrunning clutch for the second
transfer ratio is overrun in the starter mode, while another
overrunning clutch is overrun in the driving mode.
[0017] An advantageous rotary transfer device according to the
inventive concept may consist, e.g., of a planetary gear mechanism
with a sun gear, at least one planet gear and a ring gear, where
the latter may be fixedly connected to the housing, while the
planet carrier is connected to the electro-mechanical energy
converter. One overrunning device or a clutch is interposed in the
connection between the planet carrier and the electro-mechanical
energy converter, while a second overrunning device or a second
clutch is interposed between the planet gears and the combustion
engine.
[0018] In another inventive design version of the planet gear set,
the ring gear is axially movable between a first position where the
ring gear is locked to the housing and a second position where the
ring gear is locked to the planet carrier. The sun gear is rigidly
connected to the electro-mechanical energy converter, and the
planet carrier is rigidly connected to the combustion engine. The
first transfer ratio is realized by coupling the ring gear to the
housing and thereby immobilizing it, so that the torque flows from
the electro-mechanical energy converter through the rigidly
connected sun gear to the planet gears which, in turn, move the
planet-gear carrier and thereby crank up the engine with a
torque-augmenting transfer ratio. The second transfer ratio is
realized by locking the ring gear to the planet-gear carrier and
thus directly to the combustion engine, so that the second transfer
ratio is 1:1. The axial movement of the ring-gear can be controlled
in particular by using helical gears in the planetary gear
mechanisms. With a torque flow directed from the electro-mechanical
energy converter to the combustion engine, the action of the torque
will push the axially movable ring gear towards the housing so as
to engage the housing through friction-locking or form-locking
contact. If the torque flow is directed in the opposite way, i.e.,
from the combustion engine to the electro-mechanical energy
converter, the interaction of the helical tooth profiles will push
the ring gear the opposite way and into friction- or form-locking
contact with a surface portion of the planet-gear carrier. The
friction- or form-locking contact can be realized by providing the
contact surfaces of the planet-gear carrier and housing with
engagement means that are complementary to corresponding engagement
means on the respective surfaces of the ring gear. The engagement
means may be constituted for example by tooth profiles (e.g., a
so-called Hirth tooth profile), prongs or claws of a dog clutch, or
other projections. Means such as friction surfaces with
corresponding friction linings may be used either by themselves or
in a supporting function, where the friction surfaces may be
arranged either on the ring gear or on the planet gear carrier and
the housing.
[0019] If the electro-mechanical energy converter is used in a
booster mode, i.e., to assist the combustion engine in propelling
the vehicle, it is advantageous to keep the rotary transfer device
locked in the first transfer ratio, particularly at rpm rates that
are higher than those occurring in the starter mode. This may be
accomplished by at least one centrifugal body that is arranged in a
recess on the outer circumference of the planet-gear carrier and
engages a corresponding recess on the inside circumference of the
ring gear, thereby making a form-locking connection that keeps the
transfer ratio locked, although a reversal of the torque flow
occurs when the booster mode is initiated. It is advantageous to
provide a larger number of centrifugal bodies distributed over the
circumference. The centrifugal bodies can be spherical, for
example, or they can be rounded pins, in which case the edges of
the recesses in the ring gear may be rounded in axial and radial
directions. It is also advantageous if the centrifugal force on the
bodies or spheres is counteracted by a spring force that is
appropriately dimensioned to work as required.
[0020] In the same manner, a rotary transfer device can be designed
with one gear pair per transfer ratio, with the gear pairs being
engaged by freewheeling devices and clutches. For example, with two
transfer ratios, there is one clutch or overrunning clutch to be
provided for each ratio.
[0021] Further according to the inventive concept, an embodiment
may be advantageous that has two pulley pairs with different pulley
diameters for two different transfer ratios. Each of the pulley
pairs may have its own, separate belt. One pulley of each pair is
mounted on the driving shaft while the other is mounted on the
shaft of the electro-mechanical energy converter. Each of the
pulley pairs has one overrunning clutch, with the two clutches
engaging in opposite rotary directions.
[0022] In a coaxially arranged electro-mechanical energy converter,
the rotary transfer device can be arranged inside the rotor in
order to save space, where the fixed ring gear can be formed by the
stator. Furthermore, if the electro-mechanical energy converter has
a shaft running parallel to the driving shaft, with an interactive
connection through two disc-shaped transfer elements such as belt
pulleys, friction wheels, or gears, it is advantageous if the
rotary transfer device is arranged radially inside one of the
disc-shaped elements, either in the element associated with the
combustion engine or the element associated with the
electro-mechanical energy converter, because this allows the
electro-mechanical energy converter to be designed with a small
diameter. If the rotary transfer device is arranged inside the belt
pulley that belongs to the electro-mechanical energy converter, the
housing of the latter can at the same time serve as the ring gear
for the rotary transfer device, and the disc-shaped transfer
elements can provide the separate fixed transfer ratio.
[0023] In a further development of the inventive concept, a rotary
damper device and/or a rotary shock absorber is arranged between
the electro-mechanical energy converter and the combustion engine.
The rotary damper device and/or shock absorber can be arranged
between the combustion engine and the electro-mechanical energy
converter or, in a particularly advantageous way, between the
rotary transfer device and the combustion engine. The rotary damper
device and/or a rotary shock absorber used here are components that
are known per se and are inventively configured for use in the
power train of the present invention. For example, if the rotary
transfer device is arranged on the axis of the electro-mechanical
energy converter, the damper and/or shock absorber can be
accommodated radially inside the rotor. If the rotary transfer
device is arranged either at the combustion engine or at the
electro-mechanical energy converter, the rotary damper and/or shock
absorber can be accommodated radially inside the components that
provide the interactive connection, for example inside the belt
pulleys or gears.
[0024] According to the inventive concept, the rotary transfer
devices can be attached by means of their housings to the
electro-mechanical energy converter or the combustion engine. It
can further be of particular advantage, for a concept that does not
require fastening means on the combustion engine or the
electro-mechanical energy converter, if the housing is arranged to
be rotatable on its mounting axis, e.g., the axis of the driving
shaft or of the shaft of the electro-mechanical energy converter.
Following is a description of an example where the housing is
mounted on the driving shaft. The description also implicitly
applies to the case where the housing is mounted on the shaft of
the electro-mechanical energy converter, an alternative arrangement
which can be advantageous in certain applications, dependent in
particular on the shape of the installation space.
[0025] This kind of rotary transfer device is statically
indeterminate. According to the inventive concept, the housing of a
rotary transfer device that is rotatably supported on the driving
shaft can have an arm with a belt-tightener element extending
towards the endless-loop device. The housing will thus brace itself
against the endless-loop device through the tightener element with
a force that depends on the magnitude of the torque transmitted by
the endless-loop device, so that the latter will have a
torque-dependent amount of tension, advantageously including a base
amount of tension. As a particularly advantageous arrangement, the
housing and/or belt pulley is supported by ball bearings or the
like at the same axial position as the endless-loop device, i.e.,
in the same plane as the latter, because this arrangement is free
of bending forces on the bearings, so that the useful life of the
bearings is increased. To optimize the cost economy of the rotary
transfer device--also in other embodiments--, a simple bearing
design, e.g. gliding bearings using sleeves of a polymer material
or the like, can be used for the transfer ratio of the starter
mode, because the starter mode is employed for comparatively short
time periods in comparison to the generator mode. Thus, the
starter-mode related elements are less prone to wear.
[0026] In a further possible design for a statically indeterminate
arrangement of the housing, the shaft of the belt-pulley is
separate from the driving shaft, with a force-locking connection
between the shafts, e.g., through a gear pair. The housing can be
rotatably mounted on the driving shaft and also rotatably connected
to the shaft of the belt-pulley. When a torque is acting on the
rotary transfer device, the belt pulley shaft yields to the torque
by moving about the center of rotation of the driving shaft, but is
constrained by the tension of the endless-loop device. The distance
d that can be selected between the rotary axis of the belt pulley
and the axis of the driving shaft needs to be large enough,
including a safety factor, so that the shaft of the belt-pulley
shaft cannot make a full turn, i.e., spin unconstrained about the
driving shaft. The upper limit for the distance d is determined
primarily by the design dimensions, so that an advantageous range
for d is between 20 cm and 1 cm. Planetary gear mechanisms can
advantageously be used in this embodiment--including designs with
an axially movable ring gear as described above.
[0027] According to the inventive concept, it is also possible to
design statically indeterminate arrangements for transfer devices
using gear pairs, e.g., two gear pairs for two transfer ratios. For
example, two gears with oppositely oriented overrunning clutches
and their respective mating gears are rotationally constrained to
the belt pulley, where the shaft of the belt pulley is again offset
from the driving shaft. Here two, the belt pulley is constrained by
the tension of the endless-loop device.
[0028] It can be advantageous, if essential components of the power
train, e.g., the rotary transfer device and/or the gears, are made
of metal and/or a polymer material, or of a combination of both.
Furthermore, components such as housings, covers and/or flanges may
be die-cut, stamped, and/or deep-drawn. It can furthermore be
advantageous, depending on assembly requirements, to use screws,
rivets, welds and/or keyed constraints as connecting means.
[0029] According to the invention, it can be particularly
advantageous if the electro-mechanical energy converter is arranged
so that it coaxially surrounds the driving shaft at what is usually
the belt-drive side. The arrangement of the electro-mechanical
converter on the side that faces away from the vehicle transmission
offers some general advantages in comparison to an arrangement with
two parallel shafts on the belt-drive side or coaxial arrangements
where the electro-mechanical energy converter is axially interposed
between the combustion engine and the vehicle transmission.
[0030] One of the advantages is that the rotor of the
electro-mechanical energy converter, because of its moment of
inertia, can serve as a flywheel, so that the flywheel on the
transmission side of the engine can be omitted in the design,
except for the friction surfaces of the clutch that is needed with
a shift transmission. The arrangement may include a rotary shock
absorber for the power train in the area of the electro-mechanical
energy converter or on the transmission side of the driving shaft.
A rotary damping device can advantageously be arranged in the
torque flow path between the driving shaft and the rotor of the
electro-mechanical energy converter, so that the latter is to a
large extent isolated from torsional vibrations, or the torsional
stresses on the driving shaft with rotary oscillations of the rotor
mass can be reduced by uncoupling the rotor mass from the driving
shaft. It may be particularly advantageous if the rotary vibration
damper is designed to provide effective vibration isolation above a
critical frequency. This is achieved by placing circumferentially
acting energy-storing devices between the rotor mass and a mass
that is connected directly to the driving shaft, e.g., a flywheel
with an optimized amount of mass according to given design
requirements. The rotor mass and the flywheel mass are rotatable in
relation to each other, so that they work as a dual-mass flywheel
with the aforementioned advantageous properties, whereby the
resonance frequency of the power train can be moved to a range
below the idling rpm range and thus outside of the driving rpm
range of the vehicle. It can also be advantageous if the damper is
operative only within a segment of the operating range of the power
train, e.g., with a given transfer ratio between the driving shaft
and the rotor and/or in a given operating mode, e.g., in the
driving mode, while the damper action is inoperative in the
starting mode.
[0031] It can further be advantageous to use a rotary shock
absorber in parallel with the damper. Furthermore, in another
embodiment, the rotor mass can be used as a shock absorber mass.
The torsional rigidity and the amount of damping in the coupling
between the rotor and the driving shaft can be tuned to the
resonant frequency of the driving shaft.
[0032] It can furthermore be advantageous to use a rotary transfer
device between the rotor and the driving shaft in a module
combination with a rotary shock absorber and a torsional vibration
damper. The combined module may be partially filled with oil or
grease, so that the components are permanently lubricated. It may
be advantageous to isolate the meshing gear profiles from the
torsional vibrations in order to achieve a low noise level and to
make the gears last for the life of the vehicle.
[0033] A rotary transfer device between the rotor and the driving
shaft with at least two rpm-transfer ratios can be shifted, e.g.,
by the axial thrust between helical gears, by centrifugal clutches,
overrunning clutches and the like. As a further alternative, the
rotary transfer device can be designed to be shifted form the
outside, e.g., by braking and or locking individual gears by means
of magnetic clutches, magnetic brakes, magnetically switched dog
clutches and/or actuator-operated friction clutches, so that
different transfer ratios can be realized through different shift
combinations of these devices.
[0034] The automatic, externally actuated shifts can be
synchronized by appropriate means such as synchronizer rings and
similar devices that allow gear shifts dependent on the difference
in rpm rates, or the electro-mechanical energy converter can be
actively controlled to reach the rpm rate required for
synchronization. This can be accomplished, for example before a
shift to a speed-amplifying ratio, i.e., changing from a high to a
low rpm-rate of the electro-mechanical energy converter, if the
amount of power supplied to the electro-mechanical energy converter
is reduced to a level where the faster of the clutch components to
be engaged will be slowed down during the synchronization process
to approximately match the rpm-rate of the components that will
establish the new torque transfer path after the shift.
Analogously, before a shift to a speed-reducing ratio, the rpm-rate
of the electro-mechanical energy converter can be increased by
raising the power level for a short time interval, so that the
difference in rpm-rates between the components engaged in the new
torque transfer path is minimized. If during the synchronization
process, the electro-mechanical energy converter is running too
slowly, the anticipated drag torque is compensated. In the opposite
case, where the electro-mechanical energy converter is running too
fast, the slower of the mating components will during a short time
interval be accelerated by the electro-mechanical energy
converter.
[0035] The jump in power required for synchronizing the
electro-mechanical energy converter can be in the range of one to
several kilowatts, its magnitude being determined by the
synchronization torque associated with the corresponding
synchronization rpm rate. Given that the synchronization process by
definition involves that the rpm-rates of the transfer components
to be engaged are brought closer to each other, the power jump is
greatest at the beginning of the synchronization interval. During a
synchronization period, whose length is determined by the design of
the coupler- and shifter elements, the amount of power to be
injected is based on the mass moment of inertia of the parts to be
accelerated and on the change of rpm rate, the latter being a
function of the transfer ratio of the rotary transfer device.
[0036] The amount of power that the electro-mechanical energy
converter can absorb or generate to assist in the synchronization
process depends on the operating mode. For example, if the
electro-mechanical energy converter is working at maximum output
rate in the generator mode, the generator torque cannot be further
increased, based on principle. It can be advantageous if the power
usage is reduced, for example by switching off different
power-consuming devices, or by switching off the power from the
battery. Thus, the electro-mechanical energy converter is
artificially enabled to immediately provide a large amount of
torque during a synchronization phase, while the onboard power grid
is held at a voltage level higher than the battery-charging
voltage, so that other power-consuming devices can be kept fully
operative.
[0037] A "soft" synchronization can be achieved in particular if
the electro-mechanical energy converter is controlled so that the
rpm rate for synchronization between the components to be engaged
in the torque flow path for the new transfer ratio is approached
with as low a change gradient as possible.
[0038] This applies analogously to a change from a low rpm rate to
a high rpm rate of the electro-mechanical energy converter, where
the torque of the latter can be "artificially" increased by
switching on additional energy-consuming devices in order to "throw
off load" during the shifting process. This can be made even more
effective if the electro-mechanical energy converter is put into a
motor mode. A higher amount of energy absorption can also be
achieved if the electro-mechanical energy converter is operated
with a lesser degree of efficiency.
[0039] In order to make the shift processes as comfortable as
possible for the driver even with rapid rpm-changes, it is further
proposed to change the shift-rpm level during operation, i.e.,
while the electro-mechanical energy converter is in the driving
mode. For example in combination with exhaust turbo-charged
engines, the shift-rpm level can be set at an rpm rate where a
significant charging pressure is built up by the kinetic energy of
the exhaust gas, so that the increased acceleration at the end of
the "turbo gap" is available for the shift process and the
electrical losses during the synchronization can thereby be
compensated.
[0040] It is particularly advantageous in a power train according
to the inventive concept, if mechanical energy is fed into the
propulsion system during deceleration phases of the vehicle, where
the energy is stored mechanically, e.g., as kinetic energy of a
flywheel, such as the rotor mass of the electro-mechanical energy
converter, so that the stored energy is available for a subsequent
acceleration or start-up phase of the combustion engine or for
conversion and storage as electrical energy. For concepts of this
kind, where the driving shaft of the drive source (combustion
engine) turns also during energy-recovery phases, e.g., if the
electro-mechanical energy converter cannot be uncoupled from the
combustion engine by a clutch, it is proposed to reduce the drag
torque of the combustion engine through the following advantageous
measures, which can be used either individually or in combination
while the power train is operating in a drag mode:
[0041] The energy losses from engine drag can be reduced by leaks
and by changing the load on the engine by a forced opening of the
valves during the drag-mode phase. This measure can be used with
electro-mechanical, electromagnetic, hydraulic and pneumatic
valve-actuator systems. However, a mechanical actuator element may
likewise be used advantageously.
[0042] The losses in the intake may be reduced by opening the
throttle valve, e.g., through an existing actuator in vehicles with
a so-called "E-Gas" feature (known in the US as cruise
control).
[0043] The energy losses due to friction in the auxiliary modules
may be reduced, e.g., by using electrically powered instead of
belt-powered oil- and water pumps.
[0044] The frictional energy losses in the valve system may be
reduced by using a drive mechanism for the valves that is not
directly coupled to the crank shaft and can be switched off during
a drag phase.
[0045] As the energy lost in the drag mode increases strongly with
the engine rpm rate, the energy loss may be reduced by a change of
the transmission ratio. For example, the transmission ratio can be
adjusted conveniently by way of a stepless transmission (including
continuously variable transmissions and hybrid transmissions with
power branching), a multi-step automatic transmission, or an
automated manual transmission. To reduce the energy lost in the
drag mode, the transmission ratio can be set dependent on the
transfer ratio of the electro-mechanical energy converter and the
optimum operating point (rpm rate) that is associated with the
transfer ratio. The optimal transmission ratio can be determined by
a control unit, where both the drag-loss reduction and the optimum
operating point of the electro-mechanical energy converter can be
taken into account.
[0046] The energy loss due to drag during phases when the torque
flow is reversed can be reduced by switching off or reducing the
power delivered to auxiliary devices and energy-consuming devices,
except those that serve a safety function, or where the occupants
would immediately notice a reduction in comfort, e.g., electrical
heaters, air-conditioning compressors and the like. It can also be
advantageous to network the energy-consuming devices through a
common interface (e.g., through a CAN, i.e., a central area
network), in order to switch specifically targeted energy consuming
devices on or off. From an energy point of view, this allows the
combustion engine to be operated at higher compression and with
reduced fuel consumption, when the engine is in the driving
mode.
[0047] If a power train has a starter/generator and a combustion
engine, but the two cannot be uncoupled from each other by means of
a clutch, for example to save cost, it may be advantageous to
improve the energy recovery by reducing the drag torque on the
combustion engine, or the energy loss due to the drag torque,
through one or a combination of several of the following
measures:
[0048] reducing the losses due to compression and expansion;
[0049] reducing the losses at the intake by minimizing the air-flow
resistance of the control and throttle elements in the drag
mode;
[0050] reducing the energy loss due to friction by using auxiliary
devices, e.g., oil- and/or water pumps, that are independent of the
combustion engine, and/or valve-actuating mechanisms which, at
least in the drag mode, are not driven by the combustion
engine;
[0051] switching off non-essential energy-consuming devices such as
electric heaters, air conditioners and the like.
[0052] It may be advantageous to reduce the energy losses due to
leaks and the alternation of the air flow by holding the valves
open when the engine is in drag mode. This can be accomplished by
means of an electro-mechanical, electromagnetic, hydraulic or
pneumatic and, specifically, a mechanical valve actuator. Losses
due to the throttling of the air flow can be minimized by holding
the throttle valve open by means of an automatic throttle actuator
as is used with the so-called "E-Gas" feature (better known as
cruise control). The energy lost due to friction in electrically
operated auxiliary devices can be reduced during drag-mode phases
by controlling those devices based on characteristic parameter
fields. The friction in the valve mechanism will be eliminated if
the latter is turned off when the power train is operated in the
drag mode.
[0053] As a rule, the energy loss due to drag increases with an
increasing rpm rate of the combustion engine. It can therefore be
advantageous if the rpm ratio of the vehicle transmission, e.g., a
continuously variable transmission, an automated manual
transmission, a multi-speed automatic transmission, or a
power-branched hybrid transmission, is set automatically at a
high-speed level (overdrive), where the ratio may be adjusted to
the optimum operating point of the electro-mechanical energy
converter, and both the transmission ratio and the operating point
of the electro-mechanical energy converter can be set by a control
that optimizes the operating economy of the power train.
[0054] The power delivery, up to a complete shut-off of the
auxiliary devices and energy-consuming units that are not directly
essential to driving safety or to the comfort of the occupants can
be controlled advantageously by a central communication system such
as a CAN-bus, whereby the energy-consuming units can be controlled,
i.e., switched on and off, according to predetermined priorities,
so that the combustion engine can be operated during normal driving
phases at a higher compression and with reduced fuel
consumption.
[0055] The novel features that are considered as characteristic of
the invention are set forth in particular in the appended claims.
The improved apparatus itself, however, both as to its construction
and its mode of operation, together with additional features and
advantages thereof, will be best understood upon perusal of the
following detailed description of certain presently preferred
specific embodiments with reference to the accompanying
drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0056] In the following detailed description, the invention is
explained on the basis of embodiments illustrated in the attached
drawings, wherein:
[0057] FIGS. 1a-d represent different possible arrangements of a
power train according to the invention.
[0058] FIG. 2 represents a portion of a rotary transfer device
according to the invention arranged on the shaft of the
electro-mechanical energy converter, with two clutches.
[0059] FIG. 3 represents a portion of a rotary transfer device
according to the invention arranged on the shaft of the
electro-mechanical energy converter, with one overrunning device
and one clutch.
[0060] FIG. 4 represents a portion of a rotary transfer device
according to the invention arranged on the crankshaft of the
combustion engine (or, in general, on the output shaft of a drive
source), with two belt-drive pulley pairs of different pulley
diameters.
[0061] FIG. 5 represents a portion of a rotary transfer device
according to the invention arranged on the output shaft of the
combustion engine, with an axially movable ring gear.
[0062] FIG. 6 represents a portion of a rotary transfer device
according to the invention, arranged on the output shaft of the
combustion engine in a statically indeterminate configuration, with
an axially movable ring gear.
[0063] FIG. 7 represents a simplified sketch of a pair of belt
pulleys with a tensioning device.
[0064] FIG. 8 represents a portion of a rotary transfer device
according to the invention arranged on the crankshaft, where a
belt-drive pulley on the side of the crankshaft is offset from the
longitudinal axis of the latter.
[0065] FIG. 9 represents a simplified sketch illustrating a
crankshaft-mounted spur gear device according to the invention,
where a belt-drive pulley associated with the crankshaft is offset
from the longitudinal axis of the latter.
[0066] FIGS. 10-17 illustrate further possible embodiments and
arrangements of elements pertaining to the subject of the present
invention.
[0067] FIG. 18 represents an embodiment with an externally
controlled lock-up of the transfer ratios.
[0068] FIG. 19 represents a further embodiment of a rotary transfer
device mounted on the output shaft of the combustion engine, with
an improved level of efficiency.
[0069] FIG. 20 represents an embodiment with an electro-mechanical
energy converter concentrically surrounding the output shaft of the
combustion engine.
[0070] FIG. 21 represents a detail of the arrangement shown in FIG.
20.
[0071] FIGS. 22 and 23 represent embodiments of an
electro-mechanical energy converter that is integrated in a vehicle
transmission.
[0072] FIGS. 24a-c represent methods of controlling an
electro-mechanical energy converter while the latter is working in
an energy-recovering mode.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0073] FIGS. 1a-d illustrate different possible arrangements of a
power train 1, 1', 1", 1'" according to the invention with a drive
source 2, 2', 2", 2'", e.g., a combustion engine, with a driving
shaft or output shaft 3, 3', 3", 3'" that can be coupled by means
of a clutch 4, 4', 4", 4'" to the input shaft 5, 5', 5", 5'" of a
driven unit 6, 6', 6", 6'", e.g., a transmission such as a
speed-changing transmission, an automatic transmission with
multiple steps, or a continuously variable transmission (CVT). An
electro-mechanical energy converter 8, 8', 8", 8'" is connected to
the output shaft 3, 3', 3" in FIG. 1a-c, and to the input shaft 5'"
in FIG. 1d through an interactive transfer connection 7, 7', 7",
7'" that transfers torque and shifts the torque-transfer ratio
automatically dependent on the torque-flow direction by means of a
rotary transfer device 9, 9', 9", 9'".
[0074] In the embodiment of FIG. 1a, the interactive connection 7
between the clutch 4 and the combustion engine 2 is arranged to
concentrically surround the output shaft 3 and to transmit torque
from the combustion engine 2 by way of the rotary transfer device 9
to the electro-mechanical energy converter 8, and vice versa in the
case where the torque originates from the electro-mechanical energy
converter 8. In an embodiment not illustrated in a drawing, the
rotary transfer device 9 is arranged on the output shaft 3, and the
interactive connection 7 is coupled through a form-locking
connection 7 directly to the shaft 8a of the electro-mechanical
energy converter 8. The latter is connected directly to the
combustion engine 2 by means of the fastening arrangement 8b, or to
another stationary component of the vehicle (not shown) in which
the power train is installed. The interactive connection 7 can be
configured as a belt drive with a belt and pulleys, as a drive with
conical discs and an endless-loop means such as a chain, or as a
friction or gear device or the like. The rotary transfer device can
be attached to the electro-mechanical energy converter 8 or the
housing of the combustion engine 2 or any other fixed component of
the vehicle, or it can be mounted in a statically indeterminate way
where the housing of the rotary transfer device or a lever
constituted by an offset between the output shaft and the
transfer-device shaft is bearing against the interactive connection
7.
[0075] FIG. 1b illustrates a power train 1' that is identical to
the power train 1 except for the following differences: The
electro-mechanical energy converter 7' in the embodiment of FIG. 1b
is arranged at the opposite side of the combustion engine 2', i.e.,
at the end of the output shaft 3' that faces away from the driven
unit 6', by means of an interactive connection 7'. The
self-shifting rotary transfer device 9' is arranged on the output
shaft 3', but could also concentrically surrounding the shaft of
the electro-mechanical energy converter 8' (in an embodiment that
is not illustrated in the drawings).
[0076] In the embodiment shown in FIG. 1c, the electro-mechanical
energy converter 8" concentrically surrounds the output shaft 3" in
the torque-flow path between the clutch 4" and the combustion
engine 2", with the stator 8a" being attached to the housing of the
combustion engine and the rotor 8b" being part of the rotary
transfer device 9". The latter is arranged radially inside the
rotor 8b", and the interactive connection 7" to the output shaft 3"
is constituted, e.g., by friction wheels or gears.
[0077] As is self-evident, an electro-mechanical energy converter
8" that coaxially surrounds an output shaft 3" can also be arranged
at the opposite end of the output shaft, i.e., on the side that
faces away from the driven unit 6", with a rotary transfer device
9" between the electro-mechanical energy converter 8" and the
combustion engine 2" arranged radially inside the rotor 8b". The
latter arrangement has already been disclosed in the U.S. Pat. No.
4,458,156, whose full content is incorporated herein by reference.
The advantage is that no major modifications have to be made at the
interface between the combustion engine 2" and the driven unit 6",
e.g., on the housing of the transmission.
[0078] FIG. 1d illustrates an embodiment whose self-shifting rotary
transfer device 9'" is integrated in the driven unit 6'", e.g., in
a speed-changing transmission. In this case, too, as in the
examples of FIGS. 1a and 1b, the rotary transfer device 9'" can be
arranged to surround the transmission input shaft 5'" or the the
shaft of the electro-mechanical energy converter 8'". A recommended
configuration of the interactive connection 7'", in addition to the
examples described above, consists in this case preferably of a
gear pair, which can also perform additional transfer-ratio
functions in the transfer device.
[0079] In an advantageous arrangement of this kind, the
electro-mechanical energy converter can be coupled to the
transmission input shaft either directly or through a
rotation-locked interactive connection. It can be particularly
advantageous if the electro-mechanical energy converter can be
uncoupled from the combustion engine by means of a clutch, and also
if a further clutch is provided between the rotary transfer device
and the driven unit, where the clutches can be friction clutches or
form-locking clutches, depending on the design of the rotary
transfer device.
[0080] FIG. 2 illustrates a partial view of the upper half along
the axis 110 of an embodiment of a rotary transfer device 109
according to the invention. Configured as a planetary gear
mechanism, the device has a sun gear 113 that is press-fit or
shrunk onto the shaft 112 of the electro-mechanical energy
converter, a set of planet gears 114, and a ring gear 116 that is
formed on the internal circumference of the housing 115 of the
rotary transfer device or is connected to the housing 115.
[0081] Each of the planet gears 114 runs on an axle 118 that is
held by a planet holder 117. The planet holder 117 has a radially
extending flange portion 117a that receives the axles 118 and an
axially extending sleeve of the shaft 112 of the electro-mechanical
energy converter.
[0082] The embodiment of FIG. 2 has two roller bearings 119,
axially separated by a spacer ring 119a and secured on the sides by
retainer rings 119b, 119c, as a tumble-free rotary support. A first
overrunning clutch 120, which carries the belt pulley 121 of the
electro-mechanical energy converter, is arranged on the outside
circumference of the axial flange portion 117b at the end that is
facing away from the radial flange portion 117a. The first
overrunning clutch 120 is secured axially between a shoulder 121a
and a retaining ring 121b inside the belt pulley 121. A second
overrunning clutch 122 is mounted directly on the shaft 112 of the
electro-mechanical energy converter, arranged inside a portion of
smaller internal diameter of the belt pulley 121 towards the side
that faces away from the planet gears 114. The second overrunning
clutch 122 is axially constrained on one side by a shoulder 112a of
the shaft 112 and on the other side by a retaining ring 112b. The
belt pulley is secured against axial dislocation by the retaining
rings 121b and 121c. The friction surface of the belt pulley 121
with grooves 121d receives the belt, which transfers torque from
the electro-mechanical energy converter to a belt pulley on the
shaft of the driving source and vice versa.
[0083] The housing 115 of the rotary transfer device 109 is
completed by the planet carrier 117, so that the planet gears 114
and the roller bearings 119 are in an enclosed space, where they
can be grease-lubricated or run in an oil bath. The gaps between
the planet carrier 117, housing 115 and shaft 112 are closed by the
seals 123, 124, 125.
[0084] A connector flange or connector bracket 126 is screwed,
riveted or welded to the side of the housing that faces the
electro-mechanical energy converter and serves to attach the rotary
transfer device 126 to the electro-mechanical energy converter by
means of holes or cutouts 126a which are arranged at a radial
distance from the shaft 112.
[0085] In the presence of a torque originating from the
electro-mechanical energy converter towards the driving shaft, the
second overrunning clutch 122 is overrun, and the torque flows from
the shaft 112 by way of the planet gears 114, the planet carrier
117 and the overrunning clutch 121 to the belt pulley 121, from
where the torque is transmitted through the belt to the shaft of
the combustion engine. The transfer ratio along this path is such
that the rpm rate is reduced, so that the electro-mechanical energy
converter can run at a higher rpm rate and correspondingly smaller
torque when working in the starter mode. The torque amplification
in this mode can be further enhanced with an additional step-down
in the rpm rate through an appropriate selection of the belt-pulley
diameters.
[0086] With a torque flowing in the opposite direction, i.e., from
the combustion engine towards the electro-mechanical energy
converter, the overrunning clutch 120 is overrun, and the torque is
introduced directly from the belt pulley 121 through the
overrunning clutch 122 into the shaft 112 of the electro-mechanical
energy converter, so that the latter is driven in the generator
mode without converting the rpm rate of the belt pulley 121.
[0087] The rotary transfer device 209 of FIG. 3 represents a
variation of the transfer device 109. A clutch 220 actuated by an
electromagnet 227 is used instead of the first overrunning clutch
120 of FIG. 2.
[0088] The electromagnet 227 is surrounded by a ring-shaped
armature 229 that is rotationally constrained to the housing 215.
At a location on its outer radius, the electromagnet 117 has a plug
connection 228 through which the electromagnet is connected to an
external current source and to an actuating connection by which the
electromagnet is energized, e.g., dependent on the direction of the
current in the electro-mechanical energy converter. The armature is
rotatably mounted on a clutch flange 231 by means of a bearing 230
that is axially secured in both directions by the retaining rings
230a, 230b. The clutch flange 231 is centered on the shaft 212 and
constrained to share its rotation by means of a connector spring
(not shown) that engages a groove 212a of the shaft 212 of the
electro-mechanical energy converter.
[0089] A radially directed part of the clutch flange 231 forms the
counter plate 231a of the clutch 220, with prongs 220a being
arranged along the outer circumference of the axially facing end
surface of the counter plate 231a. When the clutch 220 is engaged,
the prongs 220a mesh with prongs 220b of a pressure plate 233 that
is centered on the shaft 112, for a positively locked torque
transfer. When the electromagnet is actuated to engage the clutch
220, the pressure plate 233 is moved axially towards the counter
plate 231a as the latter is magnetized by way of the gap 227a. When
the electromagnet 227 is turned off, the pressure plate 233 is
moved out of engagement by means of an axially biased
energy-storing device.
[0090] Continuing along the path of the torque flow, the pressure
plate 233 is coupled to the sun gear 213 through an axially movable
rotary constraint in the form of an internal tooth profile 233b on
an axially directed extension 233a. The sun gear 213 is rotatably
supported on the shaft 212 by means of an axially directed flange
portion 213a containing a roller bearing 212b. The flange portion
213a also carries an external gear profile 213b that meshes with
the planet gears. The axles 218 of the planet gears are connected
directly to the belt pulley 221, so that the latter serves as the
planet carrier for the planet gears 214. At the axial location of
the planet gears 214, the housing 215 has a portion of larger
diameter with an internal tooth profile 216 forming the ring gear
of the rotary transfer device 209.
[0091] The belt pulley 221 is supported on the shaft 212 by means
of a bearing 219 and an overrunning clutch 222, the latter being
axially secured by retaining rings 221b and 221c. The gaps where
the housing meets the shaft 212 and the belt pulley 221 are closed
off by means of seals 223, 224 and 225.
[0092] When the clutch 220 is engaged, e.g., in the starter mode of
the electro-mechanical energy converter, the overrunning clutch 222
is overrun and the vehicle engine is started by way of the sun gear
213, the planet gears 214, and the belt pulley 221, whereby the rpm
rate of the electro-mechanical energy converter is stepped down to
a slower rpm rate of the belt pulley. After the engine has been
started and as the rpm rate increases, the clutch 220 can be
disengaged at an exactly defined point, e.g. when the current in
the electro-mechanical energy converter reverses its direction. The
torque, which now flows back from the engine to the
electro-mechanical energy converter, drives the latter directly
through the shaft 212 without an rpm change of the rotary transfer
device 209.
[0093] FIG. 4 represents a partial view of an embodiment of a
rotary transfer device 309 that automatically shifts between two
transfer ratios depending on the direction of the torque flow. This
embodiment is based on two belt drives with different transmission
ratios. Only one side of the dual belt drive is shown, i.e., the
pulleys 321 and 334 with the rotary transfer device 309.
[0094] A ring-shaped axially extending flange 331 of the rotary
transfer device 309 has an internally directed flange 331a located
about halfway between the axial ends of the flange 331. A screw
303a connects the flange 331a to the driving shaft 303 of the
combustion engine, while a rotationally locked engagement between
the axially extending flange 331 and the driving shaft 303 is
established through the splines 303b. A first ring-shaped portion
331b of the flange 331 extends axially over the driving shaft 303,
while a second portion 331c extends in the opposite axial
direction, so that the outer circumference of the ring-shaped
flange 331 provides a mounting base for the first overrunning
clutches 322a, 322b and the roller bearing 319. The latter lies
axially in between the overrunning clutches and is axially secured
by means of retaining rings 319a. The overrunning clutch 322a,
which is located on the portion 331b of the ring-shaped flange 331,
is surrounded by an axially extending flange-part 321a that is
connected to a radially oriented flange-part 321b. Attached to the
latter by means of rivets 321c is a ring-disc part 321d turning at
its outside radius into an axially directed rim portion 321e facing
away from the driving shaft 303. The belt-pulley ring 321f is
mounted on the rim portion 321e by means of a weld 321g. The flange
parts 321a, 321b, 321d can also be designed in one integral piece.
To enhance the torque-transmitting capacity, a further flange part
335 is arranged and centered on the overrunning clutch 322b, the
roller bearing 319, and the outer circumference of the axially
oriented flange part 321a. The further flange part 335 is attached
to the flange part 321a by means of screws 335a distributed at
substantially equal intervals over the circumference. A roller
bearing 336 is arranged on the outer circumference of the flange
part 335 at a radially projecting shoulder 335b and secured by a
retaining ring 336a. The roller bearing 336 rotatably supports the
housing 315. To secure the housing against axial movement and for
sealing purposes, the end of the housing is closed off with a cover
315a that is fastened to a radial flange 315c of the housing by
circumferentially distributed screws 315b, positioning the housing
axially against the roller bearing 336 by means of an axially
directed nose 315d and sealing the housing against the flange part
335 by means of a seal 324. To optimize the space filled by the
housing, the latter is designed to follow the radial contour of the
flange parts 331 and 335. At the farthest point from the driving
shaft 303, the housing contour is drawn inwards to form an axial
flange 337. The outside circumference of the flange 337 supports
the overrunning clutches 320a, 320b, which in turn receive the
flange part 331c of the flange 331 that is rigidly connected to the
driving shaft 303. A radially projecting shoulder 315e at an
intermediate axial location of the housing contour serves as a seat
for a belt pulley 334. The latter consists of a ring-disc part
334a, a belt-pulley ring 334b to receive the belt, and a
reinforcing ring 334, where the three last-named parts are welded
to each other.
[0095] In the starter mode of the rotary transfer device 309, the
electro-mechanical energy converter drives both of the belt pulleys
321, 334 through their respective belts (not shown). Assuming equal
pulley diameters on the side of the electro-mechanical energy
converter, the pulley 321 due to its bigger diameter has the
greater rpm reduction ratio than the pulley 334. Therefore, the
overrunning clutches 322a, 322b are designed to be locked while the
overrunning clutches 320a, 320b are designed to be overrun in the
starter mode, so that the torque produced by the electro-mechanical
energy converter is introduced to the driving shaft by way of the
flange parts 321b, 321a and the flange 331.
[0096] In the generator mode of the electro-mechanical energy
converter, the overrunning clutches 322a, 322b are overrun while
the overrunning clutches 320a, 320b are locked. The torque-flow
path in this case leads from the driving shaft 303 through the
flange 331, the overrunning clutches 320a, 320b, and the housing
315 to the belt pulley 334. With its smaller diameter, the belt
pulley 334 drives the electro-mechanical energy converter at an rpm
ratio that is better suited for the generator mode. The two rpm
ratios depend on the respective diameter ratios of the pulleys in
the two belt drives. The two rotary transfer ratios can be
superimposed on a common base ratio.
[0097] FIG. 5 illustrates an embodiment of a rotary transfer device
409 in accordance with the invention. The rotary transfer device
409 is mounted on the driving shaft 403 by means of a support
flange 438, attached by a screw 403a that is accessible through a
round opening 413c in the sun gear 413. The housing 415 is centered
on the engine housing 402 by means of a flange part 437 of L-shaped
cross-section that is rigidly attached to the engine housing
through a set of screws 402a distributed along a circle. The axial
leg 437a of the L-shaped flange part 437 is inserted into a
matching recess of the housing 415 and rotationally locked to the
latter through splines 437b.
[0098] The housing 415 consists of the housing portions 415a, 415b,
415c that are welded together, but it can also be formed integrally
like the other components through appropriate shaping techniques.
Enclosed by the housing 415 is a chamber 445 containing the damper
device 439, the shock absorber 440, as well as the planetary gear
mechanism 409a with its sun gear 413, planet gears 414 and the
axially movable and rotatable ring gear 416.
[0099] A roller bearing 419 is arranged on the outer circumference
of the flange part 415a, seated against a radially projecting
shoulder 415d of the flange part 415a. The roller bearing is seated
without axial play against an elongated leg of a U-profiled ring
419a that is open towards the roller bearing 419 and is axially
secured by a retaining ring 419b. The roller bearing 419 rotatably
supports the belt-pulley cage 442 on the housing 415. The
belt-pulley cage 442 is shaped to follow the contour of the housing
415 with a minimal gap 441. It consists of the L-shaped flange
442a, belt-pulley 421, connector ring 443 and disc part 444, and it
is axially secured on the roller bearing 419 by a radially
inward-projecting nose 442b of the axial portion of the flange 442a
and by the retainer ring 419c. At the outer circumference of its
radial portion, the L-shaped flange 442a carries the belt pulley
421, which is ring-shaped and welded to the L-shaped flange. The
other side of the ring-shaped belt pulley 421 is welded to the
axially adjacent connector ring 443, to which the disc part 444 is
connected by means of screw 444a. The disc part 444 has at its
inner circumference a reinforced rim 444b protruding axially in
both directions. The reinforced rim 444b has threaded holes
distributed over its circumference, where an outward-projecting
flange 413a of the sun gear 413 is attached by means of screws
413b, whereby a sealed and rotationally fixed connection is
established between the sun gear 413 and the disc part 444.
[0100] The planet carrier 417 of the planetary gear mechanism 409a
holds the planet gears 414 by means of the axles 418 and the
interposed bearings 414a, 414b. An axial projection 438a of the
support flange 438, which is attached to the driving shaft 403,
rotatably supports the planet carrier 418 by means of a roller
bearing 436 that is axially secured by the radially projecting
shoulder 438b and the retainer ring 436a. The planet carrier 417
has at its outer circumference a form-fitting connection to the
damper device 439 by way of the gear profile 446.
[0101] Based on its functional principle, the dual-ratio transfer
device 409 provides an rpm reduction from the electro-mechanical
energy converter to the engine, e.g., when working in the starter
mode. With the geometry according to the illustrated embodiment,
the reduction ratio is 1:5. The torque-flow path leads from the
belt-pulley 421 through the disc part 444 to the sun gear 413.
Through the helical gear profile 413e, the sun gear 413 drives the
(preferably three) planet gears 414. The planet carrier 417 is
opposed by the driving shaft through the damper device 439, so that
the ring gear 416, because of its helical gear profile 416a, is
pushed axially to move away from the driving shaft 403, so that a
form-locking engagement is established between the prongs 416b and
415d on the ring gear 416 and housing 415, respectively. The
helical pitch of the gear profile 416a is selected so that the ring
gear 416 is pushed in the aforementioned axial direction already at
a torque that is smaller than the opposing torque of the driving
shaft 403, against the three-part slide bearing 449 with the
radially acting annular spring 449a, which is provided to direct
the frictional torque load acting between the axial flange part
417a of the planet carrier 417 and the ring gear 416. To keep the
ring gear from moving too far, a retainer ring 415e is snapped onto
the housing part 415c at the end of the prongs 415d. By the
form-locking engagement of the prongs, the ring gear 416 is coupled
to the housing 415, so that the driving shaft is rotationally
coupled to the output part 438c (at the transfer ratio of the
planetary gear mechanism 409a) as the gear profile 446 engages the
input part 447 which, in turn, acts through the energy-storing
devices 448 on the output part 438c. The latter has pockets 438d to
receive and compress the energy-storing devices 448, so that the
input part 447 and the output part 438c are rotatable in relation
to each other against the opposing force of at least one
energy-storing device 448 that extends over at least a part of the
circumference and serves to dampen rotary perturbations in the
power train. The torque is transferred from the output part 438c to
the driving shaft 403 by way of the support flange 438. As
mentioned above, this torque-flow pattern represents the starter
mode, where the combustion engine is started at an rpm rate that is
reduced from the rpm rate of the electro-mechanical energy
converter.
[0102] An absorber 440 for rotary shocks and vibrations is arranged
parallel to the damper device 439. The absorber 440 includes a
ring-shaped mass 440a with at least one pocket 440b in which an
energy-storing device 440c is seated, extending over at least part
of the circumference. The ring-shaped mass 440a is rotatable
relative to the input part 438d that is connected to the support
flange 438 (e.g., by welding) against the opposing force of the
energy-storing device 440c.
[0103] After the engine has been started, the direction of the
torque flow is reversed, i.e., the torque now originates from the
driving shaft 403. The planet carrier 417 is opposed by the inertia
of the electro-mechanical energy converter, and because of the
torque interacting with the helical tooth profile, the ring gear is
pushed axially towards the side of the driving shaft. This causes a
form-locking engagement between the prongs 416c on the ring gear
416 and corresponding windows or cut-outs 417b of the planet
carrier 417.
[0104] As the aforementioned form-locking engagement takes place
while the planet carrier 417 is already in motion and the ring gear
416 is approximately standing still, there is an
engagement-blocking ring 450 provided to protect the prongs 416c
from damage. The blocking ring 450 has on its outside a conical
friction-contact engagement with the ring gear 416, while an
inward-directed nose 450a of the blocking ring 450 engages a
corresponding groove of the planet carrier with play. When the
rpm-rates of the ring gear 416 and the planet carrier 417 are
approximately equal--and as a result of the torque being
transmitted through the helical gear profile 416a--the teeth of the
axially directed tooth profile 450b of the blocking ring 450 engage
the matching circle of holes 416d of the ring gear, in opposition
to the force of the axially biased energy-storing device 450c, and
thereby open the way for the engagement between the prongs 416c and
windows 417b to take place. When the torque-flow direction is
reversed, the parts 450b, 416c are disengaged from each other as
the energy-storing device 450c moves the blocking ring 450 axially
apart from the planet carrier 417.
[0105] After the form-locking engagement between the prongs 416c
and the windows 417b has been established, the planet carrier 417
turns directly with the planet gears, as the ring gear 416 is
locked to the planet carrier. The torque flows without rpm change
by way of the axles 418 and the planetary gears 414 to the sun gear
413 and from there through the disc part 444 to the belt pulley 421
which, by way of the belt (not shown) drives the electro-mechanical
energy converter.
[0106] If the electro-mechanical energy converter is operated in a
booster mode, i.e., to assist the engine, or if it is to be used as
the sole source of propulsion for the vehicle (where the torque
flow is originating from the electro-mechanical energy converter),
it is desirable to have a means of preventing the rotary transfer
device from shifting into the starter-mode transfer ratio when the
rpm-rate is more than the starter-mode rpm rate. This is
accomplished with a centrifugal device with spherical balls, ring
segments, or pins 452 that are resting in recesses 451 distributed
over the outside circumference of the planet carrier 416 and are
pulled by a centrifugal force into engagement with matching
recesses 453 in the ring gear, so that the planet carrier 416 and
the ring gear 417 are rotationally interlocked at higher rpm-rates.
If the engine comes to a stop, then the spherical balls or other
centrifugal elements 452 can be returned to the recesses 451,
substantially without applying a force. To facilitate the foregoing
process, the rims of the recesses 451, 453 can be shaped
appropriately, for example with profiles that are suitably tapered
off in the radial and circumferential directions, or the balls may
be push back into their recesses by small springs.
[0107] FIG. 6 illustrates a rotary transfer device 509 that is
analogous to the device 409 of FIG. 5 with regard to function and
spatial arrangement, except for the following differences:
[0108] The housing 515 of the rotary transfer device 509 is not
bolted onto the engine housing but is supported in a statically
indeterminate arrangement where the reactive torque of the housing
515 is taken up by lever 554 that extends radially along the plane
defined by the belt pulley 521 and the belt-pulley of the
electro-mechanical converter (not shown) and bears against the belt
555 (indicated symbolically). In this case the engine housing does
not need to be modified, and the rotary transfer unit 509 can be
used without design modifications of the engine. The radially outer
end of the lever 554 has an axially extending seat 556 for a shaft
556a which supports a belt-tensioning pulley 557 on a bearing 556b.
Depending on the direction of the torque, the belt-tensioning
pulley 556b pushes against one side or the other of the belt 555
pulley with a force that is in proportion to the amount of torque
being transmitted through the belt, so that the belt tension is
smaller when there is only a small amount of torque present,
whereby the useful lives of the belt and the bearings 519 and 558
are extended. The lever 554 is connected to the housing 515 by
means of a ring 554a that is formed at the end of the lever with an
axial offset towards the housing 515. An internal tooth profile of
the ring 554a engages an external tooth profile 515b of the housing
515 to establish a rotationally fixed connection, and a retaining
ring 515c secures the ring 554a in the axial direction without
play. To prevent the housing 515 from getting out of alignment with
the plane of rotation of the engine, an additional roller bearing
558 is arranged between the support flange 538 (which is
spline-mounted on the driving shaft 503) and the housing 515, as a
rotary support between the housing 515 and the belt-pulley cage
543. Both of the roller bearings 519 and 558 are arranged within
the running plane RE of the belt-pulleys, in order to avoid
reactive moments caused by leveraged forces. According to the
invention, additional auxiliary devices can be operated on the belt
drive, whose bearings will likewise benefit from the leverage-free
arrangement. The belt 555 can be pre-tensioned with a base amount
of force to ensure the proper functioning of the belt drive.
[0109] FIG. 7 illustrates an embodiment of a belt drive 759 in a
schematically simplified format. A lever 754 is attached to the
housing 715 of a rotary transfer device. An energy-storing device
761 connecting the tensioning pulleys 757a and 757b directly to
each other and pulling them towards each other is attached to the
lever 754. The two stretches of the belt 755 run between the
tensioning pulleys 757a, 757b and the energy-storing device 761, so
that the belt 755 (which connects the belt pulleys 762, 721 on the
respective axes of rotation 703, 762 of the engine and the
electro-mechanical energy converter) is pre-tensioned on both sides
by the force of the energy-storing device 761. Additional auxiliary
devices can be incorporated in the belt drive 759, as well as in
any other embodiment of an interactive connection between the
driving shaft and the shaft of the electro-mechanical energy
converter.
[0110] In the embodiment of a rotary transfer device 809 according
to FIG. 8, the driving shaft 803 and the belt pulley 821 are
arranged on two different axes 803a and 865, respectively, at a
distance d from each other. The belt pulley 821, from its outer
radius towards the axis 865, is composed of a belt-contact surface
821a, an L-shaped flange 821b, a disc part 821c receding axially in
the radial range of the driving shaft 803 so as to accommodate the
planetary gear mechanism 809a, as well as a hub 821d with an
external spline profile 821e, where all of the foregoing parts of
the belt pulley 821 are welded to each other. The gear 813 is
rotationally locked to the hub 821d through an internal spline
profile 813a and held in place by the screw 813b. The gear 813 with
the belt pulley 821 is support in the housing 815 by means of the
roller bearing 813c. The housing 815 surrounds the gear 813 on its
circumference, and a gap between the housing and the gear is closed
off by a seal 830. The gear 813 meshes with a further gear 866,
which bridges the distance d and forms the sun gear of the
planetary gear mechanism 809a arranged on the shaft 803 with the
central axis 803a. The sun gear 866 meshes with the planet gears
814 that are supported by means of their axles 818 on the planet
carrier 817, while the housing 815 (consisting of the parts 815a
and 815b) carries an internal tooth profile 816 that forms the ring
gear. The housing 815 is supported on the one hand by the axially
secured and sealed roller bearings 819, 836 on the support flange
838 that is splined and screwed onto the driving shaft 803, and on
the other hand on an axial projection 866a of the sun gear 866. The
latter, in turn, runs on two overrunning clutches 820 that are
arranged between the outer circumference of an L-shaped flange 866b
and the internal circumference of an axial extension 838a of the
carrier flange 838 on the side that faces away from the driving
shaft 803. The clutches 820 are arranged as a parallel pair with
the same overrunning direction, in order to achieve a larger
torque-transmitting capacity. The planet carrier 817 runs on a
triplet of parallel overrunning clutches 822 arranged on the
outside circumference of the support flange 838. The respective
directions of the overrunning clutches 820, 822 are selected
appropriately, so that as a result, the rotary transfer device 809
will work as follows:
[0111] In the case where a torque originates from the driving shaft
803, the overrunning clutch 820 is engaged, so that the torque is
transmitted from the shaft 803 to the sun gear 866, while the
clutch 822 is overrun. The torque is transferred to the gear 813
and passed on to the belt pulley 821, from where it is transmitted
by way of the belt to the electro-mechanical energy converter. At
the beginning of this phase, the belt-pulley axis 865 is rotated
about the axis 803a of the driving shaft 803 up to the point where
the rotation is constrained by the belt that is thereby being
tightened. The offset d between the axes 803a and 865 needs to be
large enough so that at a given amount of belt tension and
dependent on the amount of friction at the pulley contact surface
821a, the axis 865 cannot slip through and make a full turn about
the axis 803a. This can under normal conditions be prevented, if d
is larger than 10 mm. The upper limit for the distance d depends on
the dimensional constraints for the installation of the transfer
device 809 and may be as high as 250 mm.
[0112] In an operating situation where the torque flow is directed
from the electro-mechanical energy converter by way of the belt
pulley 821 into the rotary transfer device 809, the latter will
turn in the opposite direction about the axis 803a until it is
again constrained by the tension of the belt from turning further.
The torque is now transmitted from the gear 813 to the sun gear 866
which, in turn, drives the planet gears 814, while the clutch 820
is overrunning. The torque-flow path continues--with a reduction of
the rpm rate according to the transfer ratio of the planetary
mechanism--through the planet carrier 817, the now engaged
overrunning clutch 822, and the support flange 838 to the driving
shaft 803, whereby the engine is started up.
[0113] FIG. 9 schematically illustrates an example of a rotary
transfer device 909 where the axis 965 of the belt-pulley 921 is
offset from the axis 903 of the driving shaft. The transfer device
909 consists of two spur-gear pairs 967, 968. Two overrunning
clutches 920, 922 are arranged to automatically shift between the
two transfer ratios corresponding to the two directions of the
torque flow.
[0114] The first gears 967a, 968a of the pairs 967, 968 are
rotationally fixed on the belt-pulley shaft 965, while the second
gears 967b, 968b are connected to the driving shaft 903 through the
overrunning clutches 920, 922 with opposite overrunning directions.
The housing 915 surrounds the rotaqry transfer device 909 and is
supported on the shaft 903 by means of roller bearings 936a,
936b.
[0115] In the starter mode, the overrunning clutch 920 is engaged,
while the overrunning clutch 922 is being overrun, i.e., idling in
a freewheeling state, so that the rpm rate from the
electro-mechanical energy converter is reduced in the transfer to
the driving shaft 903. In the generator mode, the overrunning
clutch 922 is engaged, while the overrunning clutch 920 is
freewheeling. The respective gear diameters are selected such that
the step in rpm rates is smaller in the generator mode. As
described in the context of FIG. 8, the housing 915 of the rotary
transfer device is constrained by the belt, so that it is not
necessary to anchor the housing 915 on the engine housing.
[0116] The rotary transfer device 1009 shown in a sectional view in
FIG. 10 is supported directly by an electrical starter/generator by
means of a sleeve-shaped connector 1038 that is mounted on the
shaft 1012 of the electro-mechanical energy converter. (The latter
is not shown in the drawing.) The mounting attachment includes a
form-locking connector element 1003d to transmit torque, and a bolt
1003a to secure the connector 1038 in the axial direction.
[0117] The rotary transfer device 1009 has a housing 1010 to
accommodate the elements of a planetary gear mechanism,
specifically the ring gear 1016, the planet gears 1014, the planet
carrier 1017, the sun gear 1018, as well as a number of actuating-
or shifting elements.
[0118] The housing 1010 is mounted rotatably in relation to the
sleeve-shaped connector 1038, in the illustrated arrangement by a
roller-bearing arrangement 1019, specifically a ball bearing. The
housing 1010 includes a ring-shaped component 1020 of angular
cross-section, which is connected to a second housing component
1021, in the illustrated case by means of screws. The housing part
1020 carries a surface profile 1022, preferably for an endless
loop-type of transfer device such as in particular a spur belt. In
the illustrated example, the surface profile 1022 is formed
directly on the housing part 1020.
[0119] The gears 1014, 1016, 1018 of the planetary gear mechanism
1009 are helical gears. The ring gear 1016 is mounted with axial
mobility within the housing 1010. In addition, the ring gear 1010
is rotatable in relation to the sun gear 1018. In the embodiment of
FIG. 10, the sun gear 1018 is formed directly on the hub-like
connector part 1038. The ball bearing of the bearing arrangement
1019 is also received directly on the connector part 1038.
[0120] The housing part 1020 forms a belt pulley and is rigidly
attached to the planet carrier 1017 through bolted connections
1023. The axially movable ring gear 1016 is coupled through a
ball-ramp mechanism 1024 to a ring-shaped component 1025 that
surrounds the shaft 1012. An energy-storing device in the form of a
wave-shaped spring 1026 is axially pre-tensioned between the ring
gear 1016 and the ring-shaped component 1025. The ring-shaped
component 1025 is rotatably supported in the housing
1010--specifically on the housing part 1021--by a bearing 1027. The
bearing 1027 also holds the ring-shaped component 1025 at an
axially fixed position within the housing. The bearing 1027 is
designed to take up axial forces that are generated by the
ball-ramp mechanism 1024, as will be described below in more
detail. The ring-shaped component 1025 has at its inner radius an
axial extension 1028 supporting a clutch disc 1029. At least the
friction-generating portions 1030 of the clutch disc 1029 are
axially movable within a limited range. In the illustrated
embodiment, the axial mobility is achieved by an axial tooth- or
spline profile 1028a at the interface between the clutch disc 1029
and the axial extension 1028. However, the friction-generating
portions 1030 could also be made axially movable by using a
flexible connection with the ring-shaped component 1025, such as a
diaphragm spring or leaf springs. The clutch disc 1029 is part of a
brake- or clutch device 1031 which can be configured, e.g., as an
electromagnetic brake or clutch. An electromagnet 1032 is
schematically indicated in FIG. 10.
[0121] As mentioned above, the ring gear 1016 is axially movable,
so that the helical tooth profiles of the planetary mechanism 1009
will cause the ring gear 1016 to move either to the right or to the
left depending on the direction of the torque flow. In other words,
the direction of the horizontal force component acting on the ring
gear 1016 depends on whether the electro-mechanical energy
converter is working in the starter mode or the generator mode.
[0122] The ring gear 1016 can be rotationally coupled to the
housing 1010 by means of a clutch 1033. The clutch 1033 in the
illustrated embodiment is configured as an axial dog clutch, where
the mating parts can have a sawtooth profile arranged on a
circumference. The saw-tooth profiles of the dog clutch may serve
the purpose of generating on the ring gear an axial pushing force
that depends on the torque direction. The saw-tooth profiles may
further be designed so that the dog clutch works as an overrunning
clutch that allows a relative rotation between the housing 1010 and
the ring gear 1016 in one direction while providing a form-locking
torque transfer in the other direction. As a result, when the
clutch 1033 is engaged, the ring gear 1016 is rotationally locked
in relation to the housing, and thus to the planet carrier 1017, so
that the planetary mechanism is short-circuited, which means that
the rotary transfer ratio between the shaft 1012 and the housing
1010 is 1:1. Preferably, the transfer device 1009 is configured to
work at the 1:1 ratio when the electro-mechanical energy converter
is working in the generator mode, where the clutch 1031 is in the
disengaged condition.
[0123] The transfer device 1009 further includes an
engagement-blocking ring 1034 which provides at least a certain
degree of synchronization between the ring gear 1016 and the planet
carrier 1017, before they can be engaged to each other through the
mating profiles of the dog clutch 1033. Part of the axial force for
engaging the clutch 1033 can be applied by way of the
energy-storing device that may have the form of a wave-shaped
spring 1026. The helical profiles of the gears 1014, 1016, 1018 are
preferably designed so that with a torque-flow direction from the
vehicle engine to the electro-mechanical energy converter (i.e.,
when the latter is working in a generator mode), the resultant
axial force component will push the ring gear 1016 to the left,
whereby the clutch 1033 is engaged and the planetary gear mechanism
1009 is locked up. In this operating mode, the ring-shaped
component 1025 and the clutch disc 1029 connected to it are idling
along. The axial force that is exerted by the ball-ramp mechanism
1024 on the ring-shaped component 1025 is taken up by the bearing
1027.
[0124] When the clutch or brake 1031 is engaged, the ring-shaped
component is constrained from rotating, so that in the generator
mode of the electro-mechanical energy converter, the helical
profiles of the transfer device 1009 will exert a rightward push on
the ring gear 1016. The clutch device 1031 and the ramp mechanism
1024 thus have to take up a torque in the opposite direction
compared to the torque that occurs in the starter mode of the
electro-mechanical energy converter. The ramp mechanism 1024 is
configured so that when the brake or clutch 1031 is applied, the
ring gear 1016 will first be moved out from its leftmost position
to the right against the axial force of the energy-storing device
1026 and then locked into position in relation to the component
1025. As a result, the clutch 1033 becomes disengaged, so that the
planetary gear device 1009 will perform its rpm-converting
function. Disengaging the clutch device 1031 will allow the ring
gear 1016 to be accelerated by the torque of the belt drive, and at
the same time, the axially acting energy-storing device 1026 will
push the ring gear to the left. After the rpm rates of the ring
gear 1016 and the planet carrier 1017 have been at least
approximately synchronized, the clutch 1033 will again be engaged
and the rpm-converting function of the planetary gear mechanism
will be overridden, i.e., the rotary transfer device returns to a
direct-driving mode at a ratio of 1:1. When the planetary mechanism
is in its rpm-converting mode, the ratio factor is preferably in
the range between 1.5 and 5, and with particular preference between
2 and 4.
[0125] The clutch or brake device 1031 is supported advantageously
by the housing 1035 (indicated schematically) of the
electro-mechanical energy converter that runs on the shaft 1012.
Preferably, the rotor of the electro-mechanical energy converter is
mounted directly on the shaft 1012.
[0126] The embodiment of an electro-mechanical energy converter
1100 that is illustrated in FIG. 11 has a belt pulley 1122 with a
spur profile 1122a. In this embodiment, too, the belt pulley 1122
forms part of a housing 1110 in which a planetary gear mechanism
1109a is accommodated. The planetary mechanism 1109a has a
connector part 1138 that is firmly attached to the shaft 1112 of
the electro-mechanical energy converter, analogous to the part 1038
on the shaft 1012. The connector part 1038, configured as a sleeve,
carries a sun gear 1118, which is in this case made of one piece
with the connector part 1138. The planet carrier 1117, likewise, is
made of one piece with the belt pulley 1122. The ring gear 1116,
arranged rotatably inside the housing 1110, is connected to a
clutch disc 1129, the latter being part of a clutch device 1131
that can be shifted into and out of engagement depending on certain
operating states of a combustion engine of a vehicle that is
coupled to the electro-mechanical energy converter by the belt
drive that contains the pulley 1122. The clutch device 1131 can be
configured as, or it can contain, an electromagnetic clutch or
brake. The ring gear 1116, sun gear 1118, and planet gears 1114 of
the planetary mechanism 1109a are preferably spur gears, i.e.,
gears with teeth that are cut parallel to the axis.
[0127] The belt pulley 1122 is mounted rotatably in relation to the
connector part 1138 by means of an overrunning clutch bearing 1133.
The overrunning clutch 1133 essentially performs the function of
the clutch 1033 of FIG. 10. The embodiment of FIG. 11 has the
advantage that no axial forces are generated in the transfer device
and no ramp mechanism is required, in contrast to the embodiment of
FIG. 10.
[0128] In the starter mode, the clutch 1131 is brought into
engagement, whereby the ring gear 1116 is immobilized. Constraining
the clutch disc 1129 puts the planetary mechanism 1109a into the
larger transfer ratio. The planetary mechanism 1109a is designed so
that with the ring gear 1116 arrested, the freewheeling clutch
bearing 1133 between the sun gear 1118 and the planet carrier 1117
is overrun when the electro-mechanical energy converter on the
shaft 1112 is in the starter mode. As soon as the combustion engine
starts up and reaches a sufficient rpm rate, the torque will begin
to flow in the opposite direction, meaning that the
electro-mechanical energy converter will now be driven by the
engine, i.e., it will now operate in the generator mode. If the
clutch disc 1129, and thus the ring gear 1116, were still kept from
rotating, the planetary gear mechanism 1109a would, however,
continue to work at the transfer ratio of the starter mode. If, on
the other hand, the clutch disc 1129 is released, the ring gear
1116 will be able to rotate freely, and no power can be transmitted
in the generator mode from the belt pulley 1122 to the shaft 1112
through the gears of the planetary mechanism 1109a, which causes
the freewheeling clutch bearing 1133 to become engaged so that the
belt pulley 1122 turns synchronously with the shaft 1112. If the
ring gear 1116 is constrained, the shaft 1112 will turn faster than
the belt pulley 1122 in the generator mode, so that the
freewheeling clutch 1133 is overrun.
[0129] The rotary transfer device 1200 shown in FIG. 12 and FIG. 13
is connected to the rotor shaft 1212 of an electro-mechanical
energy converter in an analogous manner as was described in the
context of FIGS. 10 and 11. The belt pulley 1222 is connected to
the planet carrier 1217, and the shaft 1212 is connected to the sun
gear 1218. The planetary gear mechanism with the planet gears 1214,
the planet carrier 1217, the sun gear 1218, and the ring gear 1216
have helical gear profiles. The ring gear 1216 is axially movable
and shifts to one side or the other depending on the direction of
the torque flow, whereby the transfer ratio is changed dependent on
the torque-flow direction.
[0130] The ring gear 1216 is movable axially in relation a
component 1238 that can be constrained from rotating by a brake
1231 which works in an analogous manner as the brake 1031.
[0131] The angle of the helical tooth profile of the gears 1214,
1216, 1218 is selected so that the axial force components between
the teeth will be large enough to move th ring gear 1216 in the
axial direction. In the case where the shaft 1212 drives the ring
gear 1218 and the crankshaft of the combustion engine is driven by
way of the planet carrier 1217, the axial reaction in the helical
gear profile will push the ring gear 1216 to the left (in the view
of FIG. 12) and hold the ring gear 1216 in compressive contact with
the component 1238. The reactive torque is taken up and transmitted
by the contact interface through a positive engagement 1233, e.g.,
axially facing tooth profiles (so-called Hirth profiles), a
dog-clutch arrangement, etc., and/or a frictional torque transfer.
As the ring gear 1216 is immobilized because in this operating mode
the component 1238 is arrested by the brake 1231, the result is an
rpm-reduction (with a corresponding torque amplification) of
appropriate magnitude to start the engine by way of the belt pulley
1222. If, on the other hand, the belt pulley 1222 with the
connected planet carrier 1217 is driven by the crankshaft and,
consequently, the shaft 1212 is at the receiving end of the torque
flow through the sun gear 1218, the axial force component on the
ring gear 1216 will be directed the opposite way. The ring gear
1216 will thereby be pushed to the right into compressive contact
with the planet carrier 1217. The connection between the ring gear
1216 and the arrested component 1238 will be interrupted and a
different connection will be established by a frictional or
form-locking engagement 1235 (see FIG. 13) between the planet
carrier 1217 and the ring gear 1216. The planet gears and the
planet carrier will thereby be locked to the ring gear, so that the
sun gear 1218, the planet carrier 1217, the planet gears 1214 and
the ring gear 1216 will turn together with the shaft 1212 as one
rigid unit in the generator mode, i.e., with a transfer ratio of
1:1.
[0132] The transmission 1200 further has a centrifugal clutch 1236
with centrifugal elements 1237 that are pushed radially inwards by
at least one energy-storing device 1237a. The centrifugal clutch
1236 serves to additionally secure the transfer device in the shift
position shown in FIG. 13, dependent on the rpm rate of the belt
pulley 1222, which is tied to the engine rpm rate.
[0133] The transfer device 1200 shown in FIGS. 12 and 13 works in a
similar way as the device 409 of FIG. 5, except that the embodiment
of FIGS. 12 and 13 does not have a damper or absorber. However, in
many applications it can be of practical benefit if the device
1200, too, is equipped with a damper and/or absorber. As a
particularly practical configuration in connection with a
starter/generator unit that supports or includes a rotary transfer
device 1200, the damper and/or absorber may be arranged on the
crankshaft of the engine. According to known practice, the damper
and/or absorber can be integrated in the pulley on the engine side
of the belt drive.
[0134] With the designs of transfer devices according to the FIGS.
10 to 13, it is possible to also start combustion engines that
require a larger amount of starter torque. With an appropriate
design of the rotary transfer device, it is possible to achieve
bigger transfer ratios in the belt drive, in the sense of reducing
the rpm rate (and amplifying the torque) in the transfer from the
electro-mechanical energy converter to the combustion engine, as
required for starting the combustion engine. In the generator mode,
on the other hand, a suitable transfer ratio requires that the rpm
rate be reduced in the opposite direction, for a lower rpm rate of
the rotor of the electro-mechanical energy converter. This
requirement can likewise be met by the inventive embodiments and
arrangements of the rotary transfer device on the electrical
starter/generator. The arrangement of the transfer device on the
starter/generator unit has the further advantage that it allows the
transfer unit to be designed with significantly more compact
dimensions.
[0135] FIG. 14 illustrates a further embodiment of an electrical
starter/generator 1308 in a power train 1301. The power train 1301
includes a drive unit 1302, e.g., a combustion engine whose output
shaft 1303 can be coupled to a flywheel mass 1310 by means of a
clutch 1304. The rotatably supported flywheel mass 1310 can be
coupled by way of a second clutch 1304a to the input shaft 1305 of
a driven unit 1306, e.g., a transmission. Examples of possible
designs of a flywheel mass 1310 and clutches 1304, 1304a may be
found, e.g., in the German laid-open applications DE-OS 29 17 138,
DE-OS 29 31 513, and DE-OS 27 48 697. The electro-mechanical energy
converter 1308 is coupled to the flywheel mass through a belt- or
chain drive, or in certain cases by a gear connection. As an
advantageous arrangement, the electro-mechanical energy converter
1308 may be connected to a rotary transfer device 1309, where the
latter is preferably installed in a coaxial arrangement with the
rotor shaft of the electro-mechanical energy converter 1308. The
transfer device 1309 may be configured in accordance with one of
the embodiments described above, particularly as illustrated in
FIGS. 2, 3, 10, 11, 12, and 13.
[0136] FIG. 15 shows an embodiment of a power train 1401 that is
similar to the power train 1" of FIG. 1c. The vehicle transmission
1406 of the power train 1401 is a continuously variable
transmission, which allows a step-less variation of the
transmission ratio. The variable setting of the transmission 1406
is made in an essentially known manner by means of two cone pulleys
1450, 1451 which are arranged on the transmission input shaft 1454
and the transmission output shaft 1453, respectively. Each cone
pulley is made up of a pair of conically tapered discs 1450a, 1450b
and 1451a, 1451b, respectively. An endless-loop device 1452 is
seated in friction contact axially between the discs 1450a, 1450b
and between the discs 1451a, 1451b. The discs of each pair can be
moved axially towards and apart from each other by hydraulic,
mechanical and/or electrical actuating means, which will cause the
endless-loop device to change its position to a larger or smaller
running radius, whereby the desired transfer ratio between the
combustion engine 1402 and the output shaft 1453 of the
transmission 1406 can be set or changed.
[0137] The electro-mechanical energy converter 1408 is interposed
between the combustion engine 1402 and the transmission 1406,
arranged coaxially around the transmission input shaft 1454, which
lies in the same axis as the crankshaft 1402a of the combustion
engine 1402. A start-up clutch 1404 is arranged to couple and
uncouple the shafts 1402a and 1454. As a practical consideration,
the start-up clutch 1404 can be arranged in the torque flow path
between the electro-mechanical energy converter 1408 and the
transmission 1406, either as a dry clutch in a bell housing outside
of the transmission 1406, or as a wet clutch inside the
transmission housing. The clutch 1404 may be equipped with a
torsional vibration damper (not shown in the drawing), or it can be
part of a split flywheel, where the rotor 1408a of the
electro-mechanical energy converter 1408 may be designed as the
primary flywheel mass, and the clutch 1404 may be designed as the
secondary flywheel mass, with a damper device arranged in an
essentially known manner to oppose relative rotation between the
two flywheel masses 1408a and 1404 with a damping force or damping
torque.
[0138] If necessary, a transfer mechanism 1409 may be interposed in
the torque flow between the rotor 1408a and the crankshaft 1402,
arranged radially inside the envelope of the rotor and designed to
shift automatically into the appropriate transfer ratio dependent
on the operating states of the power train 1401.
[0139] The operating states include at least a starter mode and a
generator mode. In the starter mode, the clutch 1404 is preferably
disengaged, and the transfer device 1409 is set to convert the rpm
rate of the electro-mechanical energy converter to a lower rpm
rate. If the vehicle is in motion and the engine is standing still
or has been shut off to save fuel, the engine 1402 can also be
started by engaging the clutch in a controlled manner, with or
without the assistance of the electro-mechanical energy converter.
1408. In the generator mode, the rpm rate of the electro-mechanical
energy converter 1408 is either equal or smaller than the
crankshaft rpm rate. Additional possibilities include an operating
mode where both power plants, the combustion engine 1402 and the
electro-mechanical energy converter 1408, are used to propel the
vehicle; and further, an impulse-starter mode and/or an
energy-recovery mode. However, the latter modes require the
combustion engine to be equipped with electrically controlled,
e.g., piezo-electrically actuated engine valves 1402b of a kind
that can be controlled independently of the cycle phases of the
engine, so that the drag torque caused by the compression of the
engine can be at least partially removed. In the impulse-starter
mode, the valves 1402b are opened and the combustion engine is
accelerated by the electro-mechanical energy converter 1408,
whereupon the valves are closed and the engine begins to run. In
the energy-recovery mode, the electro-mechanical energy converter
1408 is used to slow down the vehicle through the decelerating
torque that is associated with the generation of electrical energy,
which is fed into an electrical storage accumulator (not shown).
The valves 1402b of the combustion engine are held open to reduce
the drag torque of the combustion engine. For a stronger braking
effect, the valves may also be closed, particularly if the
electro-mechanical energy converter 1408 is working at the limit of
its decelerating capability. It is self-evident, that the control-
and regulating processes associated with the foregoing operating
modes can be performed by a processor unit (not shown in the
drawing), and that also the fuel economy in these operating modes
can be optimized, e.g., by cutting off the fuel supply to the
cylinders that are not performing any work because their valves
1402b are held open during the compression phase of the engine
cycle.
[0140] FIGS. 16 and 17 illustrate embodiments of power trains 1501
and 1601 that are analogous to the example 1401 of FIG. 15, except
for the differences that the power trains 1501 and 1601 use a
different arrangement of the clutch 1504, 1604 and that an
additional clutch 1504a, 1604a is arranged in the torque flow
between the electro-mechanical energy converter 1508, 1608 and the
driven wheels 1560, 1660. The electro-mechanical energy converter
1508 of the power train 1501 is arranged concentrically on the
transmission input shaft 1554, while the electro-mechanical energy
converter 1608 is arranged parallel to the transmission input shaft
1654 and connected to the latter through a friction-based
interactive connection 1607.
[0141] The clutch 1504, 1604 is arranged in the torque flow between
the engine 1502, 1602 and the electro-mechanical energy converter
1508, 1608, so that the engine 1502, 1602 can be cut off from the
rest of the power train. Energy can thus be recovered independently
of the drag torque of the combustion engine 1502, 1602.
Furthermore, this arrangement allows a direct start of the engine
with the clutch 1504, 1604 engaged and the clutch 1504a, 1604a
disengaged, as well as an impulse start where both clutches are
disengaged. In the impulse-starter mode, the electro-mechanical
energy converter 1508, 1608 with the rotor-connected mass 1508a,
1608a is first brought up to speed, whereupon the clutch 1504, 1604
is engaged and the engine 1502, 1602 is started. In order to
stabilize the rpm rate of the engine 1502, 1602, particularly when
the latter is idling with the clutch 1504, 1604 disengaged, it can
be advantageous to arrange an additional flywheel mass 1502c, 1602c
on the crankshaft 1502a, 1602a. In some cases it may also be
advantageous to turn off the power plant 1502, 1602 when the clutch
1504, 1604 is disengaged, with an automatic restart when the clutch
1504, 1604 is re-engaged. The flywheel mass of the rotor 1508a,
1608a can in addition serve as a mechanical energy storage device
during an energy-recovery phase. With a continuously variable
transmission 1406, 1506, 1606, as shown in FIGS. 15, 16, 17,
respectively, this has the advantage that in the energy-recovery
mode, an underdrive ratio can be set in the rotary transfer from
the wheels 1560, 1660 to the rotor 1508a, 1608a, so that a high
degree of vehicle deceleration is achieved because of the strong
acceleration of the rotor, so that the latter can also store
mechanical energy in the form of rotational kinetic energy, in
addition to generating electrical energy. To subsequently
accelerate the vehicle again, the stored kinetic energy can be
returned to the wheels by setting the transmission 1406, 1506, 1606
at an appropriate ratio. The mechanical energy recovery has the
advantage that no energy is lost to conversion.
[0142] It is self-evident that the clutch 1504a, 1604a can also be
arranged at a location in the torque flow between the
electro-mechanical energy converter 1508, 1608 and the transmission
1506, 1606. The clutches 1504, 1604, 1504a, 1604a may be configured
as dry or wet clutches and can be accommodated in the transmission
housing or in a bell housing on the transmission 1506, 1606.
Furthermore, the continuously variable transmission 1406, 1506,
1606 shown in FIGS. 15-17 can also be replaced by any other type of
vehicle transmission such as, e.g., a step-shifting automatic
transmission, a manually shifted transmission or the like.
[0143] FIG. 18 illustrates an embodiment of a rotary transfer
device 1609 that is similar to the transfer device 409 of FIG. 5,
with one difference: While the device 409 has a centrifugal
mechanism to keep the transfer device locked in an rpm-amplifying
position when the electro-mechanical energy converter is in a
torque-generating mode, e.g., to boost the propulsive power of the
engine, the rotary transfer device 1609 of FIG. 18 uses an
externally controlled locking device 1680 to lock up either of the
two transfer ratios.
[0144] The locking device 1680 has an externally controlled
electromagnet 1681 and lock units that are distributed along a
circle. Each lock unit consists of a push member 1682, a wedge
member 1683, and a locking member such as a ball 1685. The
electromagnet 1681 exerts an axial force on the wedge members 1683
against the opposition of an axially acting energy-storing device
1684 that is seated at the internal circumference of an axial
extension 1613f of the sun gear 1613. The locking balls 1685 serve
to lock up the axial position of the ring gear 1616 through a
form-locking engagement between the ring gear 1616 and the axial
extension 1613f. In the illustrated position of the ring gear 1616,
the balls 1685 are seated in the circumferential ring groove 1686a,
while in the other of the two operating positions (indicated as
1616' in dash-dotted lines), the balls are seated in the ring
groove 1686b. To change the engagement of the balls from one of the
ring grooves to the other, the wedge members 1683, which have an
appropriate ramp geometry 1683a, are moved out of their locking
positions against the spring-bias action of the energy-storing
device 1684 by energizing the electromagnet 1681, while the ring
gear 1616 is moving axially as a result of the axial force
component generated by the helical gears. In their unlocked axial
positions, the wedge members 1683 allow the balls 1685 to be pushed
radially inwards into the radially ramped recesses 1683a by the
profile shape of the groove 1686a or 1686b.
[0145] The embodiment of a rotary transfer device 1709 in FIG. 19
is similar to the device 409 in FIG. 5 and is optimized with regard
to its efficiency by reducing the energy loss that occurs in narrow
gaps due to laminar shear in the lubricating grease or oil. The
improvement is achieved by optimizing the spatial arrangement and
avoiding narrow gaps between components that rotate relative to
each other inside the stationary housing 1715 that is attached by
means of a holder 1702 to the engine housing (not shown in the
drawing). This dictates the choice of a different functional
principle in comparison to the transfer device 409 of FIG. 5. The
slope angle of the helical tooth profile 1715a between the planet
gears 1714 and the ring gear 1716 is reversed, so that the ring
gear is pushed axially towards the holder 1702 and coupled to the
housing 1715 through a form-locking profile engagement 1716c for
the shift to an rpm-reducing transfer ratio. The torque received
from the electro-mechanical energy converter through the belt
pulley 1743 is transmitted through the sun gear (which is connected
to the belt pulley 1743) through the planetary gears 1714 to the
planet carrier 1717 which, in turn, is connected to the output
shaft of the combustion engine. This operating mode of the transfer
device is used, e.g., to start the engine.
[0146] When a torque is transmitted in the opposite direction
through the transfer device 1709, the helical gear profile 1716a
will push the ring gear 1716 in the direction pointing away from
the holder 1702, whereby the form-locking engagement of the ring
gear 1716 to the housing 1715 is released, while the ring gear
becomes connected to the planet carrier 1717 through a profile
engagement 1717a and the radially directed flange 1717b. The latter
carries an axial extension 1717c along its outside circumference. A
damper 1739 is arranged in the transition area between the radial
flange 1717b and its axial extension 1717c, and a vibration/shock
absorber 1740 is mounted at the internal circumference near the
free end of the axial extension 1717c. In contrast to the
embodiment of FIG. 5, where the damper is arranged in the
torque-flow path between the planet gears and the driving shaft,
the damper 1739 of FIG. 19 is arranged between the planet carrier
1717 and the ring gear 1716 and is only active when the transfer
device is operating in the direct mode. Thus, the damper 1739 is
uncoupled from the extreme jolts and oscillations during the start
of the engine and can therefore be of a less robust design.
[0147] To lock the ring gear 1716 in the direct-transfer position,
the transfer device 1709 has centrifugal elements 1752 that are
distributed over a circle and pass through openings 1716e of an
axial extension 1716d of the ring gear, driven outwards by the
centrifugal force and opposed by the energy-storing devices 1752b,
to engage a matching arrangement of shoulders 1752a of the damper
1739. Thus, if the torque flow is reversed at a high rpm-rate,
e.g., when switching from a generator mode to a booster mode, the
ring gear remains locked in the direct transfer ratio of the
generator mode. If the rpm-rate is subsequently lowered, the
radially acting energy-storing devices 1752b will retract the
centrifugal elements 1752 and thus release the lock on the ring
gear 1716.
[0148] With this arrangement, the rotary transfer device is
essentially free of narrow gaps between rotating and stationary
components and border surfaces, so that less energy will be used up
by shear friction in the lubricant 1785a in the space 1785 and,
consequently, the efficiency of the transfer device 1709 will be
increased.
[0149] FIG. 20 represents a portion of a power train where the
transfer device 1809 is arranged radially inside the
electro-mechanical energy converter 1808, directly on the driving
shaft, such as the crankshaft 1803 of the combustion engine 1802,
of which only a wall section is indicated in the drawing. The
transfer device 1809 is arranged at the end of the crankshaft that
faces in the opposite direction from the transmission, i.e., the
side that normally carries the belt drive for the auxiliary devices
such as the power-steering pump, air conditioner. These devices as
well as the valve-actuating mechanism can be driven in some other
way, for example electrically.
[0150] The starter/generator unit 1801a consisting of the
electro-mechanical energy converter 1808 and the rotary transfer
device 1809 is mounted on the housing 1802a of the engine 1802 as a
completely preassembled unit. Thus, the electro-mechanical energy
converter can be preassembled with the gap 1808a between the rotor
1808b and the stator 1808c already adjusted. The installation
adapter 1802b, mounted on the engine housing 1802a by means of
fasteners 1802c, holds the housing 1815 and the stator 1808c in
position relative to each other. The planet carrier 1817--which
represents the input side of the transfer device 1809 from the
direction of the engine 1802--is centered and rotationally
constrained on the driving shaft 1803 by a form-locking axial
profile, in this case represented by at least one axial pin 1803a,
and axially secured to the driving shaft 1803 by a central screw
bolt 1803 that is recessed in a central hole 1813a of the sun gear
1813 which provides access for the installation tool and can be
covered by a cap 1813b.
[0151] The installation adapter 1802b in the illustrated example is
designed as a sheet-metal stamping which has prongs 1802d
distributed over its outside circumference that are bent to stand
out in the axial direction to hold the stator 1808c. The latter is
immovably connected to the prongs 1802d, e.g., by screws, rivets,
or by welding. An axial extension 1802e at the inner circumference
of the sheet-metal stamping 1802b serves as a seat for the housing
1815. Axially oriented bolts 1802f outside the circumference of the
axial extension 1802e constrain the housing 1815 of the transfer
device 1809 from rotating against the housing 1802a of the
combustion engine 1802 by engaging suitably arranged openings
1815b, 1802g. The sheet-metal stamping 1802b is axially secured on
the housing 1802a of the combustion engine 1802 by means of
fasteners 1802c that are distributed along an outer circumference,
such as screws or hollow rivets.
[0152] The rotary transfer device 1809, which is arranged radially
inside the rotor of the electro-mechanical energy converter 1808,
works in an analogous manner as the embodiments 409, 1609 and 1709
of FIGS. 5, 18 and 19. A ring gear 1816 is pushed axially to one
side or the other by the interaction of its helical tooth profile
1816a with the helical planet gears 1814, depending on the
direction of the torque flow. The shift between the two transfer
ratios occurs through the respective engagement of either the tooth
profile 1815a or the profile 1817a. When the tooth profile 1815a is
engaged, the ring gear 1816 is rotationally constrained to the
housing 1815. Thus, a torque introduced from the rotor 1808b by way
of the flange part 1813c into the sun gear 1813 is transmitted
through the planetary gear set 1814 into the planet carrier 1817
which, in turn, starts the engine 1802 by turning the output shaft
1803 at an rpm-reducing gear ratio.
[0153] When the direction of the torque flow reverses itself, e.g.,
after the engine 1802 has been started and as the
electro-mechanical energy converter is changing into the generator
mode, the axial reactive force in the helical tooth profile 1816a
is likewise reversed, so that the ring gear 1816 is moved in the
axial direction where the tooth profile 1815a is disengaged from
the housing 1815 and the tooth profile 1817a becomes engaged to the
input part 1848a of the torsional vibration damper 1848. The latter
has an output part 1848b in rotationally fixed connection with the
rotor 1808b and the sun gear 1813. The input part 1848a and the
output part 1848b are rotatable relative to each other against the
opposition of energy-storing devices 1848c that are distributed
along a circumference, so that the rotor 1808b is connected
directly through the sun gear 1813 by way of the damper 1848 to the
planet carrier 1817 and thus to the engine shaft 1803, with a 1:1
gear ratio of the rotary transfer device.
[0154] To facilitate the shift between the transfer ratios, the
relative rotation between the ring gear 1816 and the planet carrier
1817 is restrained by a braking device, analogous to the other
rotary transfer devices with an axially movable ring gear, i.e.,
409, 1609 and 1709. Thus, the ring gear 1816 is prevented from
spinning in mesh with the planetary gears 1814 without the ring
gear 1816 being moved axially. In the illustrated embodiment, the
tooth-profiled ring 1816b of the ring gear 1816 is axially biased
by spring segments 1816c. A preferred arrangement has three spring
segments 1816c distributed along a circumference. The spring
segments 1816c have inward-directed radial prongs 1816d engaged in
openings 1817c of the planet carrier 1817. If the ring gear 1816 is
turning in relation to the planet carrier 1817, the spring segments
will produce a frictional torque between the ring gear and the
planet carrier and thereby increase the axial force component
between them. The spring segments 1816c in combination with the
openings 1817c further serve as a synchronizer for the tooth
profile 1817a. This function is illustrated in detail in FIG. 21
which shows a cut-off portion of the tooth-profile ring 1816b of
the ring gear 1816 (of FIG. 20). The spring bracket 1816c is
arranged at the inside circumference and embracing the sides of the
tooth-profile ring 1816b, with the spring-biased prongs 1816h
creating a frictional contact. The inwards directed prong 1816d
engages the cutout 1817c on the outside circumference of the planet
carrier 1817. The cutout 1817c is designed so that the prong 1816d
and thus the tooth-profile ring 1816b with the ring gear 1816 can
slide in a first section 1817c' up to a stop 1817". This occurs
with the axial displacement of the ring gear 1816 at the change
from the rpm-reducing ratio to the direct 1:1 ratio, where the
form-locking connection between the housing 1815 and the ring gear
1816 is disengaged. The stop 1817" prevents the ring gear 1816 from
moving further in the axial direction, so that the form-locking
connection through the tooth profile 1817a between the ring gear
1816 and the input part 1848a of the damper (See FIG. 20) cannot
become engaged until the rpm-differential between the gear ring
1816a and the planet carrier 1817 is almost zero. As the planet
carrier 1817 is turning still slightly faster, the prong 1816d
moves over in the circumferential direction into the second section
1817'" of the cutout 1817c. The axial force component of the
helical gear profile 1816a will now displace the helical gear 1816
further until a synchronized engagement between the ring gear 1816
and the damper input part 1848a occurs through the tooth profile
1817a. When the torque flow is reversed again, the prong 1816d will
travel in the reverse direction through the cutout 1817c. However,
the return of the prong 1816d through the cutout 1817c is of no
consequence for the relative rotation between the parts 1816 and
1848a, because no synchronization is required in this case. The
engagement of the tooth profile 1815a could likewise be assisted by
a synchronization, but this is not implemented in the embodiment of
FIG. 20, because the transfer device 1809 is normally shifted into
the rpm-reducing mode at a very slow rpm rate.
[0155] The direct transfer mode in the embodiment of FIG. 20 is
locked preferably by means of three mass segments 1852 that are set
into the ring gear 1816 and are driven radially outwards against a
stop (not shown) by the centrifugal force to axially lock the ring
gear against an axial extension 1848d of the damper 1848 when the
tooth profile 1817a is engaged. Thus, the ring gear will remain in
the direct ratio mode even with a change in the torque-flow
direction, until the rpm-rate decreases enough for the mass
segments 1852 to be driven back to their rest positions by
energy-storing devices that are not shown here but are analogous to
the devices 1752b of FIG. 19. This releases the ring gear 1816 from
its axial lock, so that the rpm-reducing mode can be engaged. Of
course, the axial lock could also be realized with other mechanisms
such as, e.g., the locking device 1680 of FIG. 18.
[0156] The individual components of the starter/generator unit
1801a are arranged and shaped essentially as shown in FIG. 20. The
diameter is determined essentially by the dimensions required for
the electro-mechanical energy converter according to the given
power specifications. The rotary transfer device 1809 is arranged
as a planetary gear device radially inside the rotor 1808b, but it
could also be configured as a stationary gear box or a
friction-wheel device. In either case, the shifting between the
different ratios could be handled electromagnetically or through
one or more electric motors, as well as by hydraulic, pneumatic, or
other means. The shift could also be externally actuated, e.g., by
means of clutches and/or brakes, including freewheeling devices
(also known as overrunning clutches).
[0157] In the foregoing embodiment, the planetary gear set 1809 is
employed in a manner where the planet carrier 1817 is connected to
the driving shaft, normally the crankshaft 1803 of a combustion
engine, and the sun gear 1813 is fixed to the rotor 1808b, while
the ring gear 1816 is engaged in one operating mode to the housing
1815 and in the other operating mode to the sun gear 1813 by way of
the interposed damper 1848. It is self-evident that the planetary
gear device can also be used in other variations to obtain at least
two rotary transfer ratios between the driving shaft 1803 and the
rotor 1808b. The planet carrier 1817 in the illustrated example is
configured as a hub with several radial steps. At an axial location
between the seat on the driving shaft 1803 and the planetary gear
set 1814, the housing is mounted by means of a bearing 1836, which
may also be configured as a double bearing to keep the housing 1815
from tumbling on the planet carrier 1817. The planetary gear set
has preferably three planet gears that are mounted near the ourside
diameter of the planet carrier 1817. The housing 1815 in the
illustrated example serves more as a stationary support rather than
an enclosure, because the space filled by the rotary transfer
device 1809 is essentially closed off to the outside by the flange
part 1813c that is connected to the sun gear, by the axially
oriented rotor carrier 1813d that is bolted together at one end
with the flange part 1813c, and by the L-shaped flange part 1813e
that is connected to the other end of the rotor carrier 1813d,
e.g., by welding. The axial leg 1813f of the L-shaped flange part
1813e is seated on the support 1815. The aforementioned parts
enclose a chamber 1885 that is at least partially filled with a
lubricant. The chamber 1885 is further closed off with a seal 1890
interposed radially between the flange part 1813e and the support
1815, and by a seal 1891 between the planet carrier 1817 and the
support 1815.
[0158] The support 1815 as well as the ring gear base 1816 are
designed preferably as sheet-metal stampings, in which case the
ring gear base 1816 has an internal seating surface 1816e for the
helically profiled gear ring 1816f. The latter is force-fitted into
the ring-gear base 1816, e.g., wedged into position.
[0159] The devices 1848, 1839 for attenuating torsional vibrations
are arranged essentially at the outer circumference of the rotary
transfer device 1809, immediately adjacent to the inside of the
rotor 1808b. The absorber 1839 has an absorber mass 1839a connected
through circumferentially acting energy-storing devices 1839b to a
flange part 1839c which, in turn, is connected to the planet
carrier 1817 by the bolts 1814e alternating with the planet-gear
axles 1814d along the circumference of the planet carrier. Thus,
the absorber 1839 is effective over the entire working range of the
rotary transfer device 1809 in both transfer ratios. In another
embodiment, which will not be described in detail herein, the
vibration/shock absorber could also be arranged at the opposite end
of the driving shaft 1803.
[0160] The damper 1848 is active only with the direct (1:1)
transfer mode, when the tooth profile 1817a is engaged. The damper
1848 uses a friction device 1840 that is operative between the
input part 1848a and the flange part 1813c that is connected to the
sun gear 1813. The friction device 1840 has a friction disc 1840a
that is pressed against the flange part 1813c by a pre-tensioned
axially acting energy-storing device 1840b. The damper 1848 can be
designed for a dual-mass flywheel effect with the inertial mass of
the rotor 1808b and an additional mass arranged in the torque flow
after the energy-storing storing devices 1848c, e.g., at the other
end of the driving shaft 1803. The dual-mass arrangement lowers the
resonant rpm-rate to a level below the engine-start rpm rate. This
is particularly effective in damping the torsional vibrations that
are introduced into the power train primarily from the engine
1802.
[0161] The flywheel masses can be optimized for the aforementioned
resonance effect and also with a view to minimizing the overall
flywheel mass, taking into account that the rotor mass represents
part of the engine flywheel mass. Accordingly, the flywheel on the
transmission side can be designed smaller, which saves space in
this part of the power plant layout. For example, with a
gear-shifting transmission, the flywheel mass may consist only of
the pressure plate of the clutch, so that space is saved for other
systems such as automatic actuators for the clutch or transmission.
It may further be advantageous to use the electro-mechanical energy
converter 1808 as an "electrical flywheel", where the
electro-mechanical energy converter 1808 works in parallel with the
engine 1802 at low rpm rates and is equipped with a suitable
control to actively compensate the torsional vibrations.
[0162] FIG. 22 represents a schematic view of an embodiment of a
power train 2001 with a combustion engine 2002, where the
transmission 2006 is a continuously variable transmission and an
electro-mechanical energy converter 2008 is integrated into the
torque flow of the transmission. The electro-mechanical energy
converter 2008 can be arranged either inside the transmission 2006
or outside of the transmission housing 2006a. The torque-transfer
arrangement 2009 may be configured with a belt or a gear set, or by
mounting the rotor 2008b directly on the primary shaft 2005 of the
transmission. The torque-transfer connection 2009 can be a
self-shifting rotary transfer device or a fixed-ratio
arrangement.
[0163] In the illustrated example, the combustion engine 2002 is
connected to the transmission input shaft 2005a through a torsional
vibration damper 2039. The transmission input shaft 2005a can be
coupled to the primary transmission shaft 2005 by means of a clutch
2004. The primary set of conical discs 2050 of the cone-pulley
transmission 2006 is rotationally tied to the primary transmission
shaft 2005. An endless-loop device 2052 such as a chain or belt
transmits torque from the primary disc set 2050 to the secondary
disc set 2051, the latter being rotationally coupled to the
secondary transmission shaft 2053. The operating principle of a
continuously variable transmission is known per se and is described
in detail for example in DE 195 44 644. A second clutch 2057 serves
to uncouple the secondary transmission shaft 2053 from the
differential 2059 and the driven wheels 2060. The clutches 2004,
2057 can be friction clutches, preferably of a laminar-disc design
and running in an oil bath. The power train 2001 further contains a
direction-reversing device, which is not shown in FIG. 22.
[0164] In the power train 2001 of FIG. 22, the electro-mechanical
energy converter 2008 is arranged in relation to the combustion
engine 2002 at the opposite end of the primary transmission shaft
2005. This configuration is particularly advantageous for
front-wheel drive arrangements with the combustion engine 2002
installed in the front part of the vehicle with either transverse
or lengthwise orientation without a drive shaft to the rear wheels.
The primary transmission shaft 2005 can extend to the outside of
the transmission housing 2006a, sealed by a shaft seal ring. The
electro-mechanical energy converter can in this case be mounted
coaxially on the primary transmission shaft 2005, with the stator
being non-rotatably connected to the housing 2006a and the rotor
being rotationally coupled to the primary transmission shaft 2005.
As an alternative, the electro-mechanical energy converter 2008 may
be arranged as illustrated in FIG. 22, i.e., on a parallel shaft
that is coupled to the primary transmission shaft 2005 by way of an
interposed rotary transfer device such as a spur-gear set or a belt
drive 2009 with adjustable cone pulleys 2009a, 2009b that hold the
belt or chain at a variably selectable radius, so that the transfer
ratio can be adjusted either by means of an external control or
through a self-adjusting arrangement based, e.g., on a centrifugal
principle. Using a rotary transfer device 2009 allows the rpm rate
of the electro-mechanical energy converter 2008 to be optimized for
the rpm range of the primary transmission shaft 2005. The rotary
transfer device 2009 could also be accommodated radially inside the
rotor, interposed between the latter and the primary transmission
shaft 2005 in a coaxial arrangement of the electro-mechanical
energy converter 2008. The latter, more compact design
configuration has the potential advantage of a cost- and weight
reduction.
[0165] FIG. 23 gives a schematic view of an embodiment of a power
train 2101 that is substantially identical to the power train 2001
of FIG. 22, except for the differences that will now be
described.
[0166] The electro-mechanical energy converter 2108 arranged at a
point in the torque flow between the clutch 2104 and the disc set
2150, either coaxial with the latter or, as illustrated, on a
parallel shaft. With the parallel arrangement, the
electro-mechanical energy converter 2108 can be either inside or
outside of the transmission housing (not shown). If arranged inside
the transmission 2109, the electro-mechanical energy converter 2108
can be encapsulated against the transmission fluid. It should be
considered self-evident that an encapsulation can have advantages
for any arrangement where one of the inventive electro-mechanical
energy converters and rotary transfer devices is integrated in a
transmission. The electric leads to the electro-mechanical energy
converter can be included in a cable tree for the control of the
transmission 2109. A common interface connection, e.g., a common
plug for the connection to the transmission components and to the
electro-mechanical energy converter, can be an advantageous design
detail.
[0167] The FIGS. 24a to 24c represent time graphs to compare three
different possibilities of a transition from a drag mode (where the
vehicle is decelerated by the engine) to a traction mode (where the
vehicle is accelerated.
[0168] FIG. 24a illustrates the time profile of the torque M for a
vehicle without energy recovery, where the combustion engine
decelerates the vehicle through the drag torque M(drag). This is
also referred to as an engine brake. At point I, the driver
initiates a request to the engine to supply power, e.g., by
depressing the gas pedal. The engine changes substantially
jolt-free into the traction mode until the rpm rate has been raised
to a level where after point II, the vehicle can be moved at the
full-load torque level III.
[0169] FIG. 24b illustrates the transition from a drag mode to a
traction mode in a vehicle that uses a state-of-the-art energy
recovery method. The torque M as a function of the time t is in an
initial phase represented by the recovery-brake torque M(rec) that
is introduced into the power train by the electro-mechanical energy
converter. The combustion engine is in this case turned off in
order to save fuel. When the driver requests engine power, the
engine is started up at point Ia. The engine is started by using
the remaining kinetic energy of the vehicle, while the
electro-mechanical energy converter continues to work in the
generator mode, using a portion M(gen) of the torque. The engine
start creates a jolt in the vehicle during the time interval
between Ia and Ib, i.e., the vehicle is at first slowed down
instead of accelerated, and there is no instantaneous increase of
the torque until the engine has been started at point Ib and is
building up torque up to point II, where the engine has attained
the full-load range III. In comparison to the smooth torque profile
of FIG. 24a, many drivers find the jolt at the restart of the
engine uncomfortable and unacceptable with regard to safety.
[0170] FIG. 24c illustrates how the electro-mechanical energy
converter can be controlled in a manner that avoids the foregoing
problem. At the outset, the vehicle is again in an energy-recovery
mode where the electro-mechanical energy converter decelerates the
car with a torque M(rec) and thereby produces electricity. When the
driver requests power at point Ia, the electro-mechanical energy
converter is switched immediately into a traction mode and injects
a torque M(E) into the power train to propel the vehicle until the
combustion engine has been started. The engine start takes place
between the points Ia and Ib. If the car has no start-up clutch, or
if the clutch is left engaged, the kinetic energy of the car and
the torque M(E) of the electro-mechanical energy converter can work
together to start the engine. If the car does have a start-up
clutch, the latter can be disengaged or run with slippage for a
short time to avoid a jolt, while the electro-mechanical energy
converter alone is used to start the engine. According to the
illustrated embodiment of FIG. 24c, the electro-mechanical energy
converter builds up the torque M(E) immediately after the driver's
request for power, providing traction and starting the engine at
the same time. At point Ib, the combustion engine has been started
up and builds up the engine torque M(eng) by increasing the engine
rpm rate until the full-load range III has been reached at point
II.
[0171] The electro-mechanical energy converter is controlled in
such a manner that the sum of the torques M(E) and M(eng) in the
time interval from the driver's request for power until the
full-load phase III has been attained at point II produces a soft
transition, e.g., without large time gradients in vehicle speed
and/or without gradient reversals. This is achieved by turning up
the electro-mechanical energy converter at least to its nominal
torque level or momentarily above the nominal torque level when the
request for power begins and preferably up to a point Ic which may
be before the start of the combustion engine. Subsequently, the
torque M(E) is decreased so that the zero cross-over into the
generator mode occurs not before the point II where the combustion
engine has reached its full-load range III. Obviously, the
electro-mechanical energy converter could also be used only to
overcome the start-up compression of the combustion engine without
supplying an additional amount of torque to the driven wheels of
the car. The electro-mechanical energy converter can work as a
motor and introduce an accelerating torque into the power train, or
it can work as a generator and introduce a decelerating torque,
depending on the transmission ratio and engine rpm rate.
[0172] The following German patent applications in their entirety
are incorporated herein by reference: DE 198 12 417, DE 198 38 036,
DE 198 33 784, DE 199 25 332, and DE 199 18 787.
[0173] Without further analysis, the foregoing will so fully reveal
the gist of the present invention that others can, by applying
current knowledge, readily adapt it for various applications
without omitting features that, from the standpoint of prior art,
fairly constitute essential characteristics of the generic and
specific aspects of the aforedescribed contribution to the art and,
therefore, such adaptations should and are intended to be
comprehended within the meaning and range of equivalence of the
appended claims.
* * * * *