U.S. patent application number 17/299644 was filed with the patent office on 2022-01-27 for hybrid drive having an internal combustion engine with reduced drag torque.
The applicant listed for this patent is Bayerische Motoren Werke Aktiengesellschaft. Invention is credited to Michael FRIEDRICH, Otmar FULL.
Application Number | 20220024294 17/299644 |
Document ID | / |
Family ID | |
Filed Date | 2022-01-27 |
United States Patent
Application |
20220024294 |
Kind Code |
A1 |
FRIEDRICH; Michael ; et
al. |
January 27, 2022 |
HYBRID DRIVE HAVING AN INTERNAL COMBUSTION ENGINE WITH REDUCED DRAG
TORQUE
Abstract
A hybrid drive for a vehicle includes an electric machine, an
internal combustion engine, and a transmission with a transmission
input shaft. The electric machine and the internal combustion
engine are coupled to the transmission input shaft such that the
electric machine and the internal combustion engine cannot be
decoupled.
Inventors: |
FRIEDRICH; Michael; (Eching,
DE) ; FULL; Otmar; (Muenchen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bayerische Motoren Werke Aktiengesellschaft |
Muenchen |
|
DE |
|
|
Appl. No.: |
17/299644 |
Filed: |
November 13, 2019 |
PCT Filed: |
November 13, 2019 |
PCT NO: |
PCT/EP2019/081094 |
371 Date: |
June 3, 2021 |
International
Class: |
B60K 6/48 20060101
B60K006/48; B60K 6/26 20060101 B60K006/26; B60K 6/24 20060101
B60K006/24; B60K 6/36 20060101 B60K006/36; B60K 6/387 20060101
B60K006/387; F16H 57/00 20060101 F16H057/00; B60K 6/547 20060101
B60K006/547 |
Claims
1.-11. (canceled)
12. A hybrid drive for a vehicle; comprising: an electric machine;
an internal combustion engine; and a transmission with a
transmission input shaft; wherein the electric machine and the
internal combustion engine are coupled to the transmission input
shaft such that the electric machine and the internal combustion
engine cannot be decoupled.
13. The hybrid drive according to claim 12, wherein: the
transmission has a wet space as part of an oil circuit of the
transmission; and the electric machine is coupled to the
transmission input shaft in the wet space of the transmission.
14. The hybrid drive according to claim 12 further comprising a
damping system for damping torsional oscillations; wherein a
crankshaft of the internal combustion engine is coupled to the
transmission input shaft via the damping system; and wherein the
electric machine is coupled to the transmission input shaft such
that in a purely electric operating mode of the hybrid drive the
crankshaft of the internal combustion engine is driven by the
electric machine via the damping system.
15. The hybrid drive according to claim 12, wherein: the
transmission has a clutch, wherein with the clutch the transmission
input shaft can be decoupled from an output shaft of the
transmission and/or from the transmission; and the electric machine
is coupled to the transmission input shaft upstream of the clutch
with respect to the output shaft of the transmission.
16. The hybrid drive according to claim 12, wherein the electric
machine is coupled to the transmission input shaft via a spur gear
stage in a fixed manner and/or such that the electric machine
cannot be decoupled.
17. The hybrid drive according to claim 12, wherein the electric
machine is coupled to the transmission input shaft via a chain in a
fixed manner and/or such that the electric machine cannot be
decoupled.
18. The hybrid drive according to claim 12, wherein the electric
machine has an operating voltage and/or a rated voltage of 70V or
less.
19. The hybrid drive according to claim 12, wherein: the
transmission is a double clutch transmission; the transmission has
a first clutch which is configured to couple the transmission input
shaft to a first component transmission of the transmission; the
transmission has a second clutch which is configured to couple the
transmission input shaft to a second component transmission of the
transmission; and the transmission has one or more shift elements
for coupling the first component transmission or the second
component transmission to an output shaft of the transmission.
20. The hybrid drive according to claim 12 further comprising a
control unit configured to determine that an output shaft of the
transmission is to be driven by the electric machine but not by the
internal combustion engine and to bring about one or more
drag-torque-reducing measures in order to reduce a drag torque
which is brought about on the transmission input shaft by the
internal combustion engine.
21. A vehicle, comprising: the hybrid drive according to claim
12.
22. The vehicle according to claim 21, wherein the vehicle has an
axle which is driven by the hybrid drive and wherein the electric
machine of the hybrid drive is disposed parallel to the axle.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
[0001] The invention relates to a hybrid drive. In particular the
invention relates to a hybrid drive which can be operated with a
drag-torque-reducing internal combustion engine.
[0002] A vehicle having a hybrid drive comprises an internal
combustion engine and at least one electric machine, which can each
be used individually and/or together in order to provide a drive
torque which is requested at a transmission of the vehicle. In
order to reduce the drag torque in the non-activated or activated
operating mode having reduced drag torque of the internal
combustion engine, one or more drag-torque-reducing measures can be
implemented. An exemplary drag-torque-reducing measure is to switch
off one or more cylinders of the internal combustion engine.
[0003] The reduction in the drag torque of the internal combustion
engine permits the non-activated internal combustion engine to be
entrained in a way which is efficient in terms of energy, wherein
the entrainment of the internal combustion engine in turn permits
prompt reactivation of the internal combustion engine in a way
which is efficient in terms of energy.
[0004] The present document is concerned with the technical problem
of providing a hybrid drive which is efficient in terms of
installation space, costs and weight and which permits flexible
switching over between different operating modes of the hybrid
drive in a way which is efficient in terms of energy and time.
[0005] It is to be noted that additional features of a patent claim
which is dependent on an independent patent claim can form, without
the features of the independent patent claim or only in combination
with a subset of the features of the independent patent claim, a
separate invention which is independent of the combination of all
the features of the independent patent claim and which can be made
the subject matter of an independent claim, of a partial
application or of a subsequent application. This applies in the
same way to technical teachings which are described in the
description and which can form an invention which is independent of
the features of the independent patent claims.
[0006] A hybrid drive for a vehicle, in particular for a motor
vehicle, is described according to one aspect. The hybrid drive
comprises at least one electric machine and one internal combustion
engine (e.g., a diesel engine or a gasoline engine). The electric
machine can have an operating voltage and/or rated voltage of 70V
or less, of 63V or less, or of 50V or less, in particular of 48V.
If appropriate, the electric machine can be configured also to use
voltage ranges above 50V (if appropriate also in the high voltage
range). The electrical energy for operating the electric machine
can be obtained from an electrical energy store (e.g., from a
lithium-ion-based battery) of the hybrid drive.
[0007] The hybrid drive can comprise a transmission with a
transmission input shaft. The transmission can be designed to
change a transmission ratio between the transmission input shaft
and an output shaft of the transmission (e.g., into two or more, or
into four or more, or into six or more stages). The output shaft
can be coupled, for example, to one or more wheels and/or to an
axle of a vehicle. The transmission typically has at least one
clutch in order to decouple the transmission input shaft from the
output shaft of the transmission and/or from the transmission
stages or to couple it thereto. The clutch can be used to change a
transmission stage of the transmission in the scope of a shifting
process of the transmission.
[0008] The transmission is preferably a double clutch transmission.
In particular, the transmission can comprise a first clutch which
is configured to couple the transmission input shaft to a first
component transmission of the transmission. Furthermore, the
transmission can comprise a second clutch which is configured to
couple the transmission input shaft to a second component
transmission of the transmission. In addition, the transmission can
comprise one or more shifting elements for coupling the first
component transmission or the second component transmission to the
output shaft of the transmission. The use of a double clutch
transmission permits shifting processes to be carried out without
an interruption in the tractive force.
[0009] The hybrid drive is embodied in such a way that the electric
machine and the internal combustion engine are coupled to the
transmission input shaft in such a way that they cannot be
decoupled and/or in a fixed fashion. In particular, the hybrid
drive can be embodied in such a way that even in the case of sole
operation of the electric machine the internal combustion engine is
entrained. The hybrid drive therefore does not have a clutch (in
particular no engine disconnect clutch) in order to decouple the
internal combustion engine from the electric machine. This permits
the electric machine to be integrated into the hybrid drive in a
way which is efficient in terms of installation space, weight and
costs. Furthermore, the entraining of the internal combustion
engine makes possible an efficient transition between different
operating modes (in particular between an operating mode with a
non-activated internal combustion engine and an operating mode with
an activated internal combustion engine) of the hybrid drive, since
at all times the internal combustion engine has the necessary
rotational speed to take up the load.
[0010] The hybrid drive can comprise a control unit. The control
unit can be configured to determine that the output shaft of the
transmission is to be driven by the electric machine but not by the
internal combustion engine. In particular it can be determined that
the hybrid drive is to be operated in a purely electrical operating
mode. In addition, the control unit can be configured to bring
about one or more drag-torque-reducing measures in order to reduce
a drag torque which is brought about at the transmission input
shaft by the internal combustion engine. Exemplary
drag-torque-reducing measures are to disconnect one or more
cylinders of the internal combustion engine or to adapt the opening
angles and/or closing angles of the inlet valves and/or outlet
valves of the internal combustion engine. Implementing one or more
drag-torque-reducing measures can permit the internal combustion
engine to be entrained in the non-energized operating mode in a way
which is efficient in terms of energy (wherein the entraining also
permits the efficient re-activation of the internal combustion
engine).
[0011] The transmission can comprise a wet space as part of an oil
circuit of the transmission. The wet space can be arranged, for
example, in a housing of the one or more clutches of the
transmission. The electric machine can be connected to the
transmission input shaft in the wet space of the transmission. In
particular, a gearwheel for connecting the electric machine can be
arranged in the wet space. This makes possible particularly
efficient connection of the electric machine since the oil circuit
of the transmission can be used to lubricate the connection of the
electric machine.
[0012] The hybrid drive can comprise a damping system for damping
torsional oscillations (e.g., a two-mass flywheel). The crankshaft
of the internal combustion engine can be coupled to the
transmission input shaft via the damping system, in order to permit
low-oscillation operation of the hybrid drive.
[0013] In addition, the electric machine can be coupled to the
transmission input shaft in such a way that in a purely electric
operating mode of the hybrid drive the crankshaft of the internal
combustion engine is driven by the electric machine via the damping
system. In other words, the electric machine is preferably located
in the drivetrain in an arrangement as follows:
[0014] internal combustion engine crankshaft, subsequently a
damping system, followed by the electric machine. This permits
low-oscillation connection of the electric machine.
[0015] In addition, in this arrangement the electric machine can be
followed by one or more clutches of the transmission which are
coupled to the transmission input shaft. In particular the electric
machine can be coupled to the transmission input shaft between the
damping system and the one or more clutches of the transmission.
This makes particularly efficient connection of the electric
machine possible.
[0016] The electric machine can be coupled to the transmission
input shaft via a spur gear stage in a fixed fashion and/or in such
a way that it cannot be decoupled. The electric machine can be
coupled in a particularly flexible way to the transmission input
shaft via a chain in a fixed fashion and/or in such a way that it
cannot be decoupled.
[0017] According to a further aspect, a (road) motor vehicle (in
particular a passenger car or a truck or a bus or a motorbike) is
described which comprises the hybrid drive described in this
document.
[0018] The vehicle can comprise an axle which is driven by the
hybrid drive, wherein the electric machine of the hybrid drive is
arranged parallel to the driven axle. This can permit installation
of a hybrid drive in a way which is particularly efficient in terms
of installation space.
[0019] It is to be noted that the devices and systems which are
described in this document can be used both alone as well as in
combination with other devices and systems which are described in
this document. Furthermore, any aspects of the devices and systems
which are described in this document can be combined with one
another in a variety of ways. In particular, the features of the
claims can be combined with one another in a variety of ways.
[0020] In the text which follows, the invention will be described
in more detail with reference to exemplary embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows an exemplary hybrid drive of a vehicle with a
double-clutch transmission;
[0022] FIG. 2 shows further details of the double-clutch
transmission illustrated in FIG. 2; and
[0023] FIG. 3 shows an optimized connection of the electric machine
of a hybrid drive to a double-clutch transmission.
DETAILED DESCRIPTION OF THE DRAWINGS
[0024] As stated at the beginning, the present document is
concerned with providing a hybrid drive which is optimized for
operation with an internal combustion engine with reduced drag
torque. In this context, FIG. 1 shows a block diagram of an
exemplary hybrid drive 100 for a vehicle. A hybrid drive 100
comprises an internal combustion engine 101 and an electric machine
102 which can be used individually or together to generate a drive
torque for the vehicle. The internal combustion engine 101 and the
electric machine 102 are arranged in such a way that the torques
generated by the respective drive motor are added together to form
an overall drive torque which is transmitted, for example, via a
transmission 104 and an output shaft 108 of the transmission 104 to
one or more wheels 109 of the vehicle. The electric energy for the
operation of the electric machine 102 can be stored in an
electrical energy store 110.
[0025] The vehicle and/or the hybrid drive 100 also comprise a
control unit 111 (e.g., an engine control unit) which is configured
to determine a requested overall drive torque. The requested
overall drive torque can be specified by a driver of the vehicle by
means of an accelerator pedal and/or by means of a setting of the
transmission 104, for example. For example, a driver can activate
the accelerator pedal to request an increased overall drive torque.
The control unit 111 can be configured to divide the requested
overall drive torque into a first torque (for the internal
combustion engine 101) and into a second torque (for the electric
machine 102). In other words, the control unit 111 can be
configured to operate the internal combustion engine 101 and the
electric machine 102 as a function of a requested overall drive
torque.
[0026] In the example illustrated in FIG. 1, the hybrid drive 100
comprises a double-clutch transmission 104 which has a first clutch
105 which is configured to couple the transmission input shaft 107
of the transmission 104 to a first input shaft 115 to form a first
component transmission 125 of the transmission 104 or to decouple
it therefrom. Furthermore, the transmission 104 has a second clutch
106 which is configured to couple the transmission input shaft 107
of the transmission 104 to a second input shaft 116 to form a
second component transmission 126 of the transmission 104 or to
decouple it therefrom. The transmission input shaft 107 can be
coupled directly or indirectly (e.g., via a two-mass flywheel) to
the internal combustion engine 101, in particular to the crankshaft
of the internal combustion engine 101.
[0027] The first input shaft 115 and the second input shaft 116 are
typically coaxial with respect to one another. In particular, the
first input shaft 115 can be a solid shaft which is encircled by
the second input shaft 116 which is embodied as a hollow shaft. The
first input shaft 115 can be coupled to the output shaft 108 via
the first component transmission 125 and a gear speed which is set
therein. Furthermore, the second input shaft 115 can be coupled to
the output shaft 108 via the second component transmission 126 and
a gear speed which is set therein. For example, the uneven gear
speeds (e.g., 1, 3, 5, etc.) can be provided by the first component
transmission 125, and the even gear speeds (e.g., 2, 4, 6, etc.) by
the second component transmission 126. The first and/or second
component transmissions 125, 126 typically have one or more
shifting elements 103 by means of which the different gear speeds
of the respective component transmission 125, 126 can be engaged in
an automated fashion and/or by means of which the respective
component transmission 125, 126 can be placed in a neutral position
(without a gear speed engaged). In a neutral position the input
shaft 115, 116 of a component transmission 125, 126 is typically
decoupled from the output shaft 108.
[0028] In the example illustrated in FIG. 1, the electric machine
102 of the hybrid drive 100 can be coupled only to one of the two
component transmissions 125, 126 or connected to only one of the
two component transmissions 125, 126. In particular, the electric
machine 102 can be or is coupled directly to the input shaft 115,
116 by one of the two component transmissions 125, 126.
Furthermore, the electric machine 102 is arranged in such a way
that coupling to the input shaft 115, 116 of the respective other
component transmission 125, 126 is possible only via the clutches
105, 106.
[0029] FIG. 2 shows further details of the double-clutch
transmission 104 which is illustrated in FIG. 1 and has an electric
machine 102 which is connected only to the second component
transmission 126 of the double-clutch transmission 104. In
particular, the electric machine 102 is arranged downstream of the
clutches 105, 106 of the double-clutch transmission 104 (which are
also referred to as starter elements) so that at least for some of
the gear speeds a coupling of the electric machine 102 to the
output shaft 108 of the transmission 104 is possible only by
closing both clutches 105, 106.
[0030] On the other hand, the electric machine 102 is arranged or
connected upstream of the output-side shifting elements 103.
[0031] The connection of the electric machine 102 illustrated in
FIGS. 1 and 2 in a purely electric operating mode of the hybrid
drive 100 is disadvantageous, since shifting processes are possible
only with interruption of the tractive force and/or by means of
assistance from a service break of the vehicle. This has adverse
effects on the comfort and/or on the energy efficiency of the
hybrid drive 100.
[0032] FIG. 3 shows a hybrid drive 100 in which the electric
machine 102 is fixedly coupled to the transmission input shaft 107
of the transmission 104. In particular, the electric machine 102
can be connected between the damping system 201 for reducing
torsional oscillations (in particular from the two-mass flywheel)
and upstream of the starter element 105, 106 (i.e., upstream of the
double clutch). It is therefore possible for there to be an
efficient and comfortable connection of the electric machine 102.
In particular, in this way it is possible to efficiently and
comfortably avoid interruptions in the tractive force during
shifting processes in the purely electric operating mode.
[0033] The connection of the electric machine 102 can be carried
out with a chain 303 or by means of a spur gear stage in the wet
space 307 of the transmission 104. In particular, a gearwheel 302
which is coupled to a gearwheel 304 of the transmission 104 via a
chain 303 in a fixed fashion and/or such that it cannot be
decoupled can be arranged on the drive axle 301 of the electric
machine 102, wherein the gearwheel 304 is fixedly coupled to the
transmission input axle 107 and/or to the primary side 305 of the
transmission 104 or is directly connected to the transmission input
axle 107 via a toothed engagement of one or more spur gear
stages.
[0034] The connection between the damping system 201 for reducing
torsional oscillations and the starter element 105, 106 forces the
coupling to the transmission input shaft 107 to take place in a
region in which the irregularity of the rotational speed is already
alleviated by the damping system 201, so that this region is
advantageous in terms of technical design criteria and in terms of
criteria of the acoustics of the vehicle. Furthermore, the
connection in the wet space 307 of the transmission 104 permits a
common oil circuit to be used for the transmission 104 for the
purpose of cooling and lubricating the connection of the electric
machine 102.
[0035] The electric machine 102 can be arranged axis-parallel to a
driven axle of a vehicle, in a way which is efficient in terms of
installation space.
[0036] The electric machine 102 therefore has a connection to the
transmission input shaft 107 which cannot be decoupled, causing the
internal combustion engine 101 to be entrained in the purely
electric operating mode. In order to reduce the drag torque of the
internal combustion engine 101, it is possible to implement one or
more drag-torque-reducing measures. For example, one or more
cylinders of the internal combustion engine 101 can be switched
off. The drag torque which is brought about by the internal
combustion engine 101 in the purely electric operating mode can
therefore be reduced.
[0037] On the other hand, the entraining of the internal combustion
engine 101 in the purely electric operating mode is advantageous,
since the entraining efficiently permits prompt re-activation of
the internal combustion engine 101 to be brought about. In other
words, the entraining of the internal combustion engine 101 makes
an efficient changeover possible between the different operating
modes (purely electric operating mode and operation with a portion
provided by an internal combustion engine) of a hybrid drive
100.
[0038] The present invention is not limited to the exemplary
embodiments shown. In particular it is to be noted that the
description and the figures are intended to represent only the
principle of the provided devices and systems.
* * * * *