U.S. patent application number 13/140169 was filed with the patent office on 2011-10-13 for hybrid drive system.
This patent application is currently assigned to ROBERT BOSCH GMBH. Invention is credited to Andreas Greis, Markus Hernier, Bjoern Noack, Christoph Weisser.
Application Number | 20110247337 13/140169 |
Document ID | / |
Family ID | 41718500 |
Filed Date | 2011-10-13 |
United States Patent
Application |
20110247337 |
Kind Code |
A1 |
Weisser; Christoph ; et
al. |
October 13, 2011 |
HYBRID DRIVE SYSTEM
Abstract
The invention relates to a hybrid drive system comprising an
internal combustion engine (11) which is operated using fuel (21)
from a fuel tank (20), and comprising a hydraulic machine (12)
which interacts with a hydraulic energy store (38). In order to
provide a hybrid drive system which requires less installation
space than conventional hybrid drive systems, the hydraulic machine
(12) is operated with the same fuel (21) with which the internal
combustion engine (11) is also operated.
Inventors: |
Weisser; Christoph;
(Gerlingen, DE) ; Hernier; Markus; (Gerlingen,
DE) ; Noack; Bjoern; (Bangalore, IN) ; Greis;
Andreas; (Stuttgart, DE) |
Assignee: |
ROBERT BOSCH GMBH
Stuttgart
DE
|
Family ID: |
41718500 |
Appl. No.: |
13/140169 |
Filed: |
December 10, 2009 |
PCT Filed: |
December 10, 2009 |
PCT NO: |
PCT/EP2009/066842 |
371 Date: |
June 16, 2011 |
Current U.S.
Class: |
60/712 |
Current CPC
Class: |
B60K 6/12 20130101; F01K
23/14 20130101; B60K 2015/03164 20130101; F04C 2210/1044 20130101;
Y02T 10/62 20130101; F01K 25/02 20130101; F04C 2210/203 20130101;
B60K 15/00 20130101; B60K 15/01 20130101; Y02T 10/6208 20130101;
Y02T 10/6282 20130101 |
Class at
Publication: |
60/712 |
International
Class: |
F01B 29/04 20060101
F01B029/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 2008 |
DE |
10 2008 054 819.7 |
Claims
1. A hybrid drive system having an internal combustion engine (11)
which is operated with fuel (21) from a fuel tank (20), and having
a hydraulic machine (12) which interacts with a hydraulic energy
store (38), characterized in that the hydraulic machine (12) is
operated with the same fuel (21) with which the internal combustion
engine (11) is also operated.
2. The hybrid drive system as claimed in claim 1, characterized in
that the hydraulic machine (12) is hydraulically connected to the
fuel tank (20) of the internal combustion engine (11) and to the
hydraulic energy store (38).
3. The hybrid drive system as claimed in claim 2, characterized in
that a pre-delivery pump (22) is connected between the fuel tank
(20) and the hydraulic machine (12).
4. The hybrid drive system as claimed in claim 1, characterized in
that a control unit (35) is connected between the hydraulic machine
(12) and the hydraulic energy store (38).
5. The hybrid drive system as claimed in claim 4, characterized in
that the control unit (35) is hydraulically connected to a clutch
(14) which is connected between the internal combustion engine (11)
and the hydraulic machine (12).
6. The hybrid drive system as claimed in claim 4, characterized in
that the control unit (35) is hydraulically connected to a
hydraulic motor (45) which is drivingly connected to a fuel
high-pressure pump (25) of a fuel injection system.
7. The hybrid drive system as claimed in claim 4, characterized in
that the control unit (35) is hydraulically connected to one inlet
of a fuel high-pressure pump (25).
8. The hybrid drive system as claimed in claim 1, characterized in
that the hydraulic energy store (38) comprises a gas pressure
accumulator which is filled with fuel and which is connected, or
can be connected, to the fuel tank (20).
9. A method for operating a hybrid drive system having an internal
combustion engine (11) which is operated with fuel (21) from a fuel
tank (20), and having a hydraulic machine (12) which interacts with
a hydraulic energy store (38), comprising operating the hydraulic
machine (12) with the same fuel (21) with which the internal
combustion engine (11) is also operated.
10. The method for operating a hybrid drive system as claimed in
claim 9, further comprising supplying a fuel high-pressure pump
(25) of the fuel injection system with fuel as a function of
requirements, said fuel being pressurized by the hydraulic machine
(12).
11. The hybrid drive system as claimed in claim 1, wherein the
hydraulic machine is driven by the internal combustion engine.
12. The hybrid drive system as claimed in claim 1, wherein in a
pump operating mode, the hydraulic machine pumps fuel from the fuel
tank to the hydraulic energy store.
13. The hybrid drive system as claimed in claim 3, characterized in
that a control unit (35) is connected between the hydraulic machine
(12) and the hydraulic energy store (38).
14. The hybrid drive system as claimed in claim 13, characterized
in that the control unit (35) is hydraulically connected to a
clutch (14) which is connected between the internal combustion
engine (11) and the hydraulic machine (12).
15. The hybrid drive system as claimed in claim 14, characterized
in that the control unit (35) is hydraulically connected to a
hydraulic motor (45) which is drivingly connected to a fuel
high-pressure pump (25) of a fuel injection system.
16. The hybrid drive system as claimed in claim 15, characterized
in that the control unit (35) is hydraulically connected to one
inlet of a fuel high-pressure pump (25).
17. The hybrid drive system as claimed in claim 16, characterized
in that the hydraulic energy store (38) comprises a gas pressure
accumulator which is filled with fuel and which is connected, or
can be connected, to the fuel tank (20).
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a hybrid drive system having an
internal combustion engine which is operated with fuel from a fuel
tank, and having a hydraulic machine which interacts with a
hydraulic energy store. The invention also relates to a method for
operating a hybrid drive system as described above.
SUMMARY OF THE INVENTION
[0002] The object of the invention is to provide a hybrid drive
system having an internal combustion engine which is operated with
fuel from a fuel tank, and having a hydraulic machine which
interacts with a hydraulic energy store, which requires fewer
components than conventional hybrid drive systems.
[0003] The object is achieved in the case of a hybrid drive system
having an internal combustion engine which is operated with fuel
from a fuel tank, and having a hydraulic machine which interacts
with a hydraulic energy store, in that the hydraulic machine is
operated with the same fuel with which the internal combustion
engine is also operated. The hydraulic machine is optionally
operated as a drive motor or as a pressure pump for the hydraulic
energy store, instead of the internal combustion engine. According
to one essential aspect of the invention, the hydraulic machine is
not operated with a conventional hydraulic fluid but rather with
fuel, preferably with diesel fuel. As a result of the consumption
of fuel during the operation of the internal combustion engine, it
is easily possible to ensure sufficient renewal of the fuel which
serves as a hydraulic fluid. A separate equalizing container for
hydraulic fluid can be dispensed with.
[0004] A preferred exemplary embodiment of the hybrid drive is
characterized in that the hydraulic machine is hydraulically
connected to the fuel tank of the internal combustion engine and to
the hydraulic energy store. According to a further aspect of the
invention, the fuel tank is used as an equalizing container for the
drive hydraulics. The hydraulic machine can be constructed and
configured in a self-priming fashion. The supply of the hydraulic
machine in the pump operating mode then occurs directly from the
fuel tank.
[0005] A further preferred exemplary embodiment of the hybrid drive
system is characterized in that a pre-delivery pump is connected
between the fuel tank and the hydraulic machine. According to a
further aspect of the invention, a pre-delivery pump which is
already present in a fuel injection system is used to supply the
hydraulic machine with fuel.
[0006] A further preferred exemplary embodiment of the hybrid drive
system is characterized in that a control unit is connected between
the hydraulic machine and the hydraulic energy store. The control
unit is preferably a control valve device by means of which the
hydraulic machine can be connected to the hydraulic energy store
and/or to the fuel tank in such a way that the hydraulic machine is
operated either as a hydraulic pump or as a hydraulic motor. The
control valve device can also be used only for switching power
levels. The pump/motor operating mode can then be set autonomously
at the drive machine.
[0007] A further preferred exemplary embodiment of the hybrid drive
system is characterized in that the control unit is hydraulically
connected to a clutch which is connected between the internal
combustion engine and the hydraulic machine. The clutch between the
internal combustion engine and the hydraulic machine requires rapid
closing and controlled opening in the transitions between the
individual operating modes. As a result of the integration of the
activation of the clutch into the drive hydraulics, the properties
of conventional electric operating devices can be surpassed.
[0008] A further preferred exemplary embodiment of the hybrid drive
system is characterized in that the control unit is hydraulically
connected to a hydraulic motor which is connected in terms of drive
to a fuel high-pressure pump of a fuel injection system. Although
this degrades the overall efficiency level for the generation of
the injection pressure in the fuel injection system, it is also
surprisingly possible to obtain advantages. For example, the
demands made of the fuel high-pressure pump can be reduced by
dispensing with an intake throttle. Furthermore, the installation
location of the fuel high-pressure pump is freely selectable since
the fuel high-pressure pump no longer has to be installed on the
internal combustion engine. Furthermore, the fuel high-pressure
pump can run separately from the internal combustion engine.
[0009] A further preferred exemplary embodiment of the hybrid drive
system is characterized in that the control unit is hydraulically
connected to one inlet of a, or of the, fuel high-pressure pump. As
a result it is possible to supply the fuel high-pressure pump with
fuel as a function of requirements, said fuel being pressurized by
the hydraulic machine. This provides advantages during rapid
starting of the internal combustion engine. By relaxing the fuel
from the drive hydraulics it is also possible, if appropriate, for
the pre-delivery means of the fuel high-pressure pump to be
dispensed with.
[0010] A further preferred exemplary embodiment of the hybrid drive
system is characterized in that the hydraulic energy store
comprises a gas pressure accumulator which is filled with fuel and
which can be connected, or is connected, to the fuel tank. The
hydraulic energy store is preferably pressurized by means of the
hydraulic machine during the pumping operation.
[0011] In a method for operating a previously described hybrid
drive system, the object specified above is achieved in that the
hydraulic machine is operated with the same fuel with which the
internal combustion engine is also operated. During operation of
the internal combustion engine, the hydraulic machine functions as
a pressure pump which is driven by the internal combustion engine.
During the motor operation, the hydraulic machine is driven by the
hydraulic energy store.
[0012] A preferred exemplary embodiment of the method is
characterized in that the fuel high-pressure pump of the fuel
injection system is supplied with fuel as a function of
requirements, said fuel being pressurized, or having been
pressurized, by the hydraulic machine. This provides advantages,
inter alia, during rapid starting of the internal combustion
engine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Further advantages, features and details of the invention
emerge from the following description in which various exemplary
embodiments are described in particular with reference to the
drawing.
[0014] In the drawing:
[0015] FIG. 1 is a highly simplified schematic illustration of a
hybrid drive system according to the invention, and
[0016] FIG. 2 shows a Cartesian coordinate diagram in which an
exemplary profile of the rotational speed of the internal
combustion engine and of the rail pressure of the hybrid drive
system illustrated in FIG. 1 is plotted against the time.
DETAILED DESCRIPTION
[0017] FIG. 1 shows, purely by way of example, a highly simplified
schematic illustration of a drive train 1 of a motor vehicle. The
drive train 1 comprises a drive axle 2 with two wheels 3, 4, which
are driven by means of the drive axle 2. The drive axle 2 can be
mechanically coupled to an internal combustion engine 11 through
the intermediate connection of a transmission 5, it being possible
to drive the drive axle 2 via said internal combustion engine 11.
Alternatively, the drive axle 2 can be driven by means of a
hydraulic machine 12 which can either be operated as a hydraulic
motor or as a hydraulic pump. A clutch 14 by means of which the
internal combustion engine 11 can be decoupled from the rest of the
drive train 1, is connected between the internal combustion engine
11 and the hydraulic machine 12.
[0018] The hybrid drive system 1 also comprises a fuel tank 20,
which is filled with fuel 21. The fuel 21 is preferably diesel
fuel, which, according to an essential aspect of the invention, is
used not only to supply the internal combustion engine 11 but is
also employed as a working fluid, in particular a hydraulic fluid,
for the hydraulic machine 12.
[0019] The fuel 21 is fed through a fuel line 24 to a fuel
high-pressure pump 25 using a pre-delivery pump 22 which is
arranged, for example, in the fuel tank 20. The fuel high-pressure
pump 25 can, however, also be of self-priming design.
[0020] The fuel high-pressure pump 25 is part of a fuel injection
system, in particular of a diesel injection system. In the fuel
high-pressure pump 25, the fuel which is sucked in or delivered
from the fuel tank 20 is subjected to high pressure and fed via a
fuel high-pressure line 27 to a central fuel high-pressure
accumulator 26 which is also referred to as a common rail. The fuel
which has been subjected to high pressure is injected from the
central high-pressure accumulator 26 into combustion chambers of
the internal combustion engine 11 via fuel injection valves 28,
which are also referred to as injectors.
[0021] The fuel 21 from the fuel tank 20 is also fed to the
hydraulic machine 12 via a filter device 31 and a hydraulic line
30. Owing drops in pressure, there was a flow through the filter
device 31 only when the fuel was relaxed in the motor operating
mode. The hydraulic line 30 can, like the fuel lines 24 and 27
described above and the further hydraulic lines described below, be
embodied as a separate line or as a duct which runs at least
partially through a housing body. The hydraulic machine 12 is
connected to a control unit 35 via a further hydraulic line 34. The
control unit 35 is preferably a hydraulic control device which is
connected to a hydraulic energy store 38 via a further hydraulic
line 36.
[0022] In the design outlined in FIG. 1, the rotational speed of
the hydraulic machine 12 corresponds, when the clutch 14 is closed,
to the rotational speed of the internal combustion engine 11, with
the result that corresponding ranges of efficiency have to be taken
into account in the configuration. Alternatively, the rotational
speed of the internal combustion engine 11 can also be stepped up
or stepped down via an intermediately connected transmission.
[0023] In the pump operating mode, the hydraulic machine 12 is
driven by the internal combustion engine 11, with the result that
fuel 21 is delivered from the fuel tank 20 into the energy store 38
via the control unit 35 using the hydraulic machine 12. Depending
on the design of the hydraulic machine 12, various circuits can be
implemented using the control unit 35. On the one hand, the
hydraulic machine 12 can be embodied so as to be self-priming in
the pump operating mode. The fluid supply to the hydraulic machine
12 then occurs directly from the fuel tank 20. Alternatively, the
hydraulic machine 12 can also be embodied so as to be
non-self-priming. According to a further aspect of the invention,
the hydraulic machine 12 can then be connected to the pre-delivery
pump 22 of the fuel injection system, as indicated by the dashed
line 39. The pre-delivery pump 22 is preferably driven
electrically. In this case, it is also possible to provide
filtering before the fuel enters the hydraulic machine 12. However,
the technical implementation of the variant indicated by the dashed
line 39 may involve problems since the volume flows which occur for
electric pre-delivery systems are relatively large.
[0024] If the hydraulic machine 12 is not of self-priming design,
the described pre-delivery concept is preferably used. However, in
certain situations it is also possible to apply the fuel pressure
from the drive hydraulics to the fuel high-pressure pump 25, as is
indicated by dashed hydraulic lines 41 and 43. The two hydraulic
lines 41, 43 are connected to one another by means of a branching
point 42. The control unit 35 is connected to the inlet side of the
fuel high-pressure pump 25 via the two hydraulic lines 41, 43. This
connection to the drive hydraulics provides advantages in the case
of rapid starting of the internal combustion engine. In addition to
the time for the synchronization of the crankshaft angle with the
camshaft and the actual acceleration of the rotational speed, the
minimum rail pressure for enabling the injection determines the
starting time. In order to shorten the latter, it is possible, in a
way analogous with rail venting, to bypass a high-pressure valve
provided in the fuel high-pressure pump 25 by applying the pressure
from the drive hydraulics, thereby biasing a sufficient rail
pressure.
[0025] In addition to the application of pressure described above,
it is also possible to stabilize the rail pressure in the vicinity
of the working pressure of the drive hydraulics during a stationary
state of the internal combustion engine through a simple regulating
process. In this context, a considerable advantage can be obtained
in terms of the loading on the high-pressure components in the load
spectrum, in particular relatively small pressure range pairs can
be obtained. In the case of a self-priming hydraulic machine 12 it
is also possible for the usual pre-delivery of the fuel
high-pressure pump 25 to occur through corresponding relaxing of
the fuel from the drive hydraulics. A conventional overflow valve
on the fuel high-pressure pump 25 for regulating the pressure of
the pre-delivery can therefore be dispensed with.
[0026] The drive of the fuel high-pressure pump 25 can be provided
mechanically by means of the internal combustion engine 11.
However, by virtue of the inventive integration of the drive
hydraulics, the drive can also be provided hydraulically via the
drive hydraulics themselves. Although this worsens the overall
efficiency level for the generation of the injection pressure, the
demands made of the fuel high-pressure pump 25 can be reduced by
dispensing with suction throttling. In this context it is possible,
in particular to reduce the pressure loading and torque peaks. The
rotational speed and the size of the fuel high-pressure pump can be
freely selected given a corresponding number of delivery
elements.
[0027] A hydraulic line 44 branches off from the junction 42 and
connects the drive hydraulics to a hydraulic motor 45 which, as
indicated by a line 46, is connected in terms of drive to the fuel
high-pressure pump 25. The fuel high-pressure pump 25 is therefore
driven using the hydraulic motor 45 via the drive hydraulics, that
is to say the hydraulic machine 12 and/or the hydraulic energy
store 38. In this drive concept, it is no longer necessary to
install the fuel high-pressure pump 25 on the internal combustion
engine 11. Accordingly, corresponding specifications relating to
the installation location of the fuel high-pressure pump 25 are
dispensed with.
[0028] The hydraulic energy store 38 serves to store energy which
is generated in a suitable vehicle operating state with the drive
hydraulics, that is to say with the hydraulic machine 12. Within
the scope of the present invention, a gas pressure accumulator has
proven particularly advantageous for this purpose. The gas pressure
accumulator provides, inter alia, the advantage that the pressure
energy which is made available by the hydraulic machine 12 in the
pump operating mode does not have to be converted for storage or
for subsequent use. From there, simple integration of a control
means for further components occurs by means of the drive
hydraulics. Furthermore, rapid charging/discharging gradients are
possible. Furthermore the gas pressure accumulator is low in weight
and requires little maintenance. In this context, the gas pressure
accumulator permits a sufficient storage duration in order to cope
with start/stop situations.
[0029] The energy flows in the drive hydraulics are controlled by
means of the control unit 35. Depending on the operating state and
on the storage content of the energy store 38, the operation of the
hydraulic machine 12 is regulated as a pump, and the energy storage
or the operation of the other hydraulically controlled components
is coordinated.
[0030] The clutch 14 is connected to the control unit 35 via a
further hydraulic line 40. The integration into the drive
hydraulics also provides a large potential here. For a starting
process with an empty energy store 38, the clutch 14 must be closed
in an unactivated fashion. Subsequently, the corresponding
actuating energy for optional opening 14 can be made available via
the hydraulic machine 12.
[0031] FIG. 2 shows, in a Cartesian coordinate diagram, the
rotational speed n of the internal combustion engine and the rail
pressure p in the central fuel high-pressure accumulator of the
fuel injection system plotted against the time t. The rotational
speed n and the rail pressure p are constant over time to a
stopping time 51 of the internal combustion engine. After the
stopping time 51, both the rotational speed n and the rail pressure
p decrease linearly over time. In this context, the rotational
speed decreases more steeply than the rail pressure. During a time
period 54 both the rotational speed and the rail pressure drop to
minimum value, for example to zero. At a starting time 52 of the
internal combustion engine, the rotational speed increases linearly
until it reaches its previous value again. As a result of the
inventive hydraulic connection to the hydraulic energy store, the
rail pressure already increases before the rotational speed and
with a larger gradient than the rotational speed.
* * * * *