U.S. patent application number 14/113290 was filed with the patent office on 2014-02-13 for heating of an exhaust gas aftertreatment system by dragging of an internal combustion engine with the aid of an electric motor.
This patent application is currently assigned to ROBERT BOSCH GMBH. The applicant listed for this patent is Julian Doerreich, Dimitrios Stavrianos. Invention is credited to Julian Doerreich, Dimitrios Stavrianos.
Application Number | 20140041368 14/113290 |
Document ID | / |
Family ID | 46085009 |
Filed Date | 2014-02-13 |
United States Patent
Application |
20140041368 |
Kind Code |
A1 |
Stavrianos; Dimitrios ; et
al. |
February 13, 2014 |
HEATING OF AN EXHAUST GAS AFTERTREATMENT SYSTEM BY DRAGGING OF AN
INTERNAL COMBUSTION ENGINE WITH THE AID OF AN ELECTRIC MOTOR
Abstract
A method is introduced for heating an exhaust-gas aftertreatment
system (15). The method has the following steps: detection of a
necessity to heat (S1) the exhaust-gas aftertreatment system (15),
and actuation (S5) of an electric motor (5) in such a way that the
electric motor (5) drags the internal combustion engine (3) which
produces exhaust gas. Here, the internal combustion engine (3) is
held at a predefinable rotational speed by the electric motor
(5).
Inventors: |
Stavrianos; Dimitrios;
(Karlsruhe, DE) ; Doerreich; Julian; (Stuttgart,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Stavrianos; Dimitrios
Doerreich; Julian |
Karlsruhe
Stuttgart |
|
DE
DE |
|
|
Assignee: |
ROBERT BOSCH GMBH
Stuttgart
DE
|
Family ID: |
46085009 |
Appl. No.: |
14/113290 |
Filed: |
April 25, 2012 |
PCT Filed: |
April 25, 2012 |
PCT NO: |
PCT/EP2012/057502 |
371 Date: |
October 22, 2013 |
Current U.S.
Class: |
60/274 ;
60/320 |
Current CPC
Class: |
F02D 41/024 20130101;
B60W 10/08 20130101; B60W 10/06 20130101; B60K 2006/4825 20130101;
F01N 9/00 20130101; Y02T 10/12 20130101; Y02T 10/47 20130101; Y02T
10/62 20130101; Y02T 10/6221 20130101; F02D 2041/026 20130101; B60K
6/48 20130101; F01N 3/00 20130101; Y02T 10/40 20130101; Y02T
10/6252 20130101; Y02T 10/6286 20130101; B60W 20/16 20160101; Y02T
10/26 20130101; Y02T 10/54 20130101 |
Class at
Publication: |
60/274 ;
60/320 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2011 |
DE |
10 2011 017 721.3 |
Claims
1. A method for heating an exhaust gas aftertreatment system, the
method comprising the following steps: detecting a need to heat the
exhaust gas aftertreatment system; controlling an electric motor
such that the electric motor drags an internal combustion engine
that produces exhaust gas; wherein the internal combustion engine
is thereby maintained at a specifiable revolution rate.
2. The method as claimed in claim 1, also comprising dragging the
internal combustion engine such that exhaust gases of the internal
combustion engine have a higher temperature than during operation
of the internal combustion engine without an electric motor.
3. The method as claimed in claim 1, also comprising selecting
injection parameters and/or ignition parameters of the internal
combustion engine such that an independent operation of the
internal combustion engine is not possible.
4. The method as claimed in claim 3, wherein the revolution rate,
as well as the injection parameters and/or the ignition parameters
are adjusted such that a temperature of the exhaust gases is
increased at the cost of a torque-generating proportion of the
combustion of the internal combustion engine compared to the
operation of the internal combustion engine without an electric
motor.
5. The method as claimed in claim 1, further comprising determining
a current temperature in the exhaust gas aftertreatment system.
6. The method as claimed in claim 5, also comprising comparing of
the current temperature with a specifiable target temperature
value; terminating the dragging process by the electric motor once
the current temperature corresponds to or exceeds the specifiable
target temperature value.
7. The method as claimed in claim 1, also comprising terminating
the dragging process by the electric motor once a specifiable time
interval since detecting a need to heat the exhaust gas
aftertreatment system is exceeded.
8. A control device, which is designed to implement the method as
claimed in 1.
9. A computer program element, wherein the computer program element
is designed to implement the method as claimed in claim 1 if it is
executed on a processor.
10. Computer-readable medium, wherein the program element as
claimed in claim 9 is stored on the medium.
Description
BACKGROUND OF THE INVENTION
[0001] Exhaust gas reduction and monitoring are important issues of
modern branches of industry. The exhaust gases of an internal
combustion engine must be treated in exhaust gas aftertreatment
systems for reasons of emission regulations among other reasons. A
certain working temperature is necessary for the optimal
functionality of an exhaust gas aftertreatment system.
[0002] The exhaust gas aftertreatment system is heated with the aid
of the exhaust gases generated in the internal combustion engine in
order to achieve or to maintain the desired working temperature.
Here a large proportion of the energy of combustion in the internal
combustion engine is used for torque generation by the engine. A
smaller proportion of the energy is output in the form of heat or
of thermal energy.
[0003] In order to achieve the emission targets, during a cold
start the catalyzer must be brought to working temperature as
rapidly as possible. One option for this is by retarding the
ignition angle. This reduces the proportion of the energy for
torque generation and at the same time increases the thermal
portion. The proportion of the energy that can be given off as heat
to the exhaust gas aftertreatment system together with the exhaust
gases cannot be increased without restriction. It is limited by the
internal combustion engine not being able to compensate for its
losses and thus running roughly or even cutting out, if the
torque-generating portion of the energy is reduced excessively.
SUMMARY OF THE INVENTION
[0004] There can thus be a need for an improvement and/or
acceleration of the heating of an exhaust gas aftertreatment
system.
[0005] Such a requirement can be satisfied by the subject of the
present invention according to the independent claims. Advantageous
embodiments of the present invention are disclosed in the dependent
claims. Features, details and possible advantages of embodiments of
the invention are discussed in detail below.
[0006] According to a first aspect of the invention, a method for
heating an exhaust gas aftertreatment system is proposed. The
method comprises the following steps: detecting a need to heat the
exhaust gas aftertreatment system; and controlling an electric
motor such that the electric motor drags the internal combustion
engine generating the exhaust gas. The internal combustion engine
is thereby maintained at a specifiable revolution rate by the
electric motor.
[0007] In other words, the idea of the invention is based on
operating the internal combustion engine regardless of how the
engine is running such that a high exhaust gas temperature exists.
A regular revolution rate profile of the internal combustion engine
is thereby guaranteed by the electric motor.
[0008] For example, for this purpose an ignition time can be
selected to be so late that a piston has moved far towards bottom
dead center before the fuel-air mixture in the combustion chamber
of the cylinder is fully burnt. This causes an increase in the
thermal energy released during combustion. But the torque or the
power of the engine decreases here at the same time. During
operation without an electric motor this could cause the internal
combustion engine to run "roughly" or to cut out. However,
according to the invention the internal combustion engine is
dragged by the electric motor and is thus maintained at a
specifiable, e.g. a constant, revolution rate. The revolution rate
can be adjusted here, for example automatically by a control device
of a vehicle or by a driver of the vehicle.
[0009] The method can e.g. be used in hybrid vehicles with internal
combustion engines and electric motors.
[0010] The exhaust gas aftertreatment system can comprise a
plurality of components, such as e.g. a catalyzer and a particle
filter. A lambda probe can also be provided in, on or before the
exhaust gas aftertreatment system. With the aid of the method
according to the invention, individual components, such as a
catalyzer and lambda probe, or the entire exhaust gas
aftertreatment system can be heated.
[0011] For detecting a need to heat the exhaust gas aftertreatment
system, e.g. a probe or a sensor can be provided, which for example
can recognize or measure a cold start of the internal combustion
engine. A temperature sensor can also be provided directly in the
exhaust gas aftertreatment system.
[0012] The control of the electric motor can include regulation or
readjustment of the revolution rate of the electric motor. The
electric motor can drag the internal combustion engine irrespective
of the torque of the internal combustion engine. The specifiable
revolution rate at which the internal combustion engine is
maintained by the electric motor can, for example, be constant or
e.g. varied by a control device or a driver of a vehicle.
[0013] The method according to the invention has the advantage that
the time until achieving an optimal working temperature of the
exhaust gas aftertreatment system, also referred to as the
"Light-Off" time, can be reduced following a cold start of an
internal combustion engine for example. Through the boosted and
accelerated heating of the exhaust gas aftertreatment system with
exhaust gases of the internal combustion engine, in particular the
necessary working temperature can be achieved faster at a catalyzer
and a lambda probe. This causes a reduction of emissions. When
using said method in hybrid vehicles the internal combustion engine
can also be shut off earlier, which causes a C02 saving.
[0014] According to one exemplary embodiment of the invention, the
internal combustion engine is dragged by the electric motor such
that the exhaust gases of the internal combustion engine have a
higher temperature than during operation of the internal combustion
engine without the electric motor at the same revolution rate. The
exhaust gas temperature is thereby increased because a greater
proportion of the energy of combustion of the internal combustion
engine is released as thermal energy.
[0015] According to another exemplary embodiment of the invention
the method also comprises the following step: selecting injection
parameters and/or ignition parameters of the internal combustion
engine such that independent operation of the internal combustion
engine is no longer possible. Injection and ignition parameters can
be e.g. the injection quantity, injection duration, injection
interval, composition of the injected fuel mixture, and the
ignition time. A higher exothermic rise in the exhaust gas is
guaranteed by selecting said parameters regardless of how the
engine is running.
[0016] For example the ignition parameters and the injection
parameters can be selected independently of the torque generation
of the internal combustion engine such that the highest possible
temperature of the exhaust gases is guaranteed.
[0017] According to another exemplary embodiment of the invention,
the specifiable revolution rate as well as the injection parameters
and/or ignition parameters can be selected or adjusted such that
the temperature of the exhaust gases is increased at the cost of
the torque generating proportion of the combustion of the internal
combustion engine in comparison with the operation of the internal
combustion engine without an electric motor.
[0018] According to another exemplary embodiment of the invention,
the method also comprises the step of determining a current
temperature in the exhaust gas aftertreatment system. The current
temperature can e.g. be determined at a component of the exhaust
gas aftertreatment system, such as e.g. at a catalyzer, or at a
lambda probe before the exhaust gas aftertreatment system. The
current temperature can be determined directly with the aid of
sensors or even indirectly, for example by using the cooling water
temperature in the area of the exhaust gas aftertreatment system.
The current temperature can for example be measured continuously or
at regular intervals. The current temperature measurement values
can be forwarded to a control device for evaluation.
[0019] According to another exemplary embodiment of the invention,
the method also comprises the following steps: comparing the
current temperature with a specifiable target temperature value;
ending the dragging process of the internal combustion engine by
the electric motor once the current temperature corresponds to or
exceeds the specifiable target temperature value.
[0020] The target temperature value can e.g. correspond to an
optimal working temperature of the exhaust gas aftertreatment
system or of components of the exhaust gas aftertreatment system.
It can be adjusted and stored e.g. in a control device, for example
of a hybrid vehicle. For example, the specifiable target
temperature value can lie in the region of 250.degree. C. The
control device can carry out a comparison between the current
measured temperature value and the specified target temperature
value and can end the dragging process accordingly once the target
temperature value is reached. After that a change to "normal mode"
can take place. The "normal mode" can be operation of a vehicle
only by means of an internal combustion engine or only by means of
an electric motor. The "normal mode" or a hybrid mode can also be
by means of a combination of electric motor and internal combustion
engine.
[0021] According to another exemplary embodiment of the invention,
the method also comprises the following step: ending the dragging
process of the internal combustion engine by the electric motor
once a specifiable time interval since the detection of a need to
heat the exhaust gas aftertreatment system has been exceeded.
[0022] The dragging process can also be terminated independently of
a measurement value of the current temperature at the exhaust gas
aftertreatment system. If e.g. the optimal working temperature of
the exhaust gas aftertreatment system has not yet been reached
after a predetermined time period, then the process is terminated
and changed to "normal mode". The specifiable time interval can
e.g. be 2 to 5 minutes since a cold start of the internal
combustion engine.
[0023] According to a second aspect of the invention, a control
device is described that is implemented to carry out the method
described above. For this purpose the control device can be
connected by lines to an internal combustion engine, an electric
motor and sensors, such as for example temperature sensors. The
control device is implemented here to receive signals, such as e.g.
measurement values of the current temperature, and to control and
regulate the operation of the internal combustion engine and of the
electric motor. For this purpose, the control device can, for
example, specify the specifiable revolution rate of the internal
combustion engine and adjust the injection and ignition
parameters.
[0024] According to a third aspect of the invention, a computer
program element is described that is designed to implement the
method described above if it is executed on a processor, for
example on a control device.
[0025] According to a fifth aspect of the invention a
computer-readable medium is described, wherein the program element
described above is stored on the medium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Other features and advantages of the invention are apparent
to the person skilled in the art from the following description of
exemplary embodiments, which however are not to be construed as
limiting the invention, with reference to the accompanying
figures.
[0027] FIG. 1 shows a schematic diagram of the method according to
an exemplary embodiment of the invention
[0028] FIG. 2 shows schematically a hybrid vehicle system with a
control unit, which is suitable to implement a method according to
an exemplary embodiment of the invention.
DETAILED DESCRIPTION
[0029] All figures are only schematic representations of devices
according to the invention and their components or of process
steps. In particular, distances and dimensional relationships are
not reproduced to scale in the figures. In the figures
corresponding elements are provided with the same reference
numbers.
[0030] In FIG. 1 a diagram of the method according to an exemplary
embodiment of the invention is illustrated schematically. In step
S1 an internal combustion engine 3 is started. In step S3 the need
to heat the exhaust gas aftertreatment system is detected. A
possible cause of the need for heating can for example be a cold
start of the internal combustion engine 3. For detection of the
need to heat the exhaust gas aftertreatment system 15, the current
temperature of the exhaust gas aftertreatment system 15 can be
measured and compared with a target temperature value, similarly to
as in step S9a. Alternatively, a cold start can be detected
directly on the internal combustion engine. If the system
determines that the exhaust gas aftertreatment system 15 must be
heated, then in step S5 the electric motor 5 is controlled such
that it drags or drives the internal combustion engine 3. Here the
electric motor 5 is regulated such that it operates the internal
combustion engine 3 with a predefined torque.
[0031] In step S7 the injection and ignition parameters of the
internal combustion engine 3 are also selected or adjusted such
that the exhaust gas aftertreatment system 15 and in particular the
catalyzer 17 disposed therein are optimally heated. The injection
and ignition parameters are selected such that the internal
combustion engine 3 can no longer operate independently. The
displacement of the injection and ignition parameters, regardless
of how the engine 3 is running, causes an increased rise of the
exhaust gas temperature. The increased temperature causes the
catalyzer 17 and the lambda probe 19 before the exhaust gas
aftertreatment system 15 to reach the optimal working temperature
faster. Thus with the aid of an electric motor 5 the so-called
light-off time is reduced and the exhaust gas emissions are
reduced.
[0032] In step S9 different process parameters can be interrogated.
Steps S9a to S9c can be carried out in parallel with each other or
alternatively to each other. In step S9a the current temperature of
the exhaust gas aftertreatment system 15 and especially of the
catalyzer 17 are determined and compared with a target temperature
value. If the current temperature value is below the target
temperature value, then as indicated by the arrow the process can
be continued, i.e. steps S5 and S7 are repeated. For this purpose,
e.g. the electric motor 5 and the injection and ignition parameters
of the internal combustion engine 3 can be readjusted with the aid
of a control device 1. If the current temperature value of the
exhaust gas aftertreatment system 15 corresponds to the specified
target temperature value or if it is higher than the target
temperature value, then in step S11 the dragging process by the
electric motor 5 is terminated and a "normal" driving mode is
initiated in the hybrid vehicle. A normal driving mode here can be
e.g. operation with the internal combustion engine. An adequate
proportion of the energy of combustion of the internal combustion
engine 3 can thereby be provided for the torque generation, so that
independent operation of the internal combustion engine 3 is
possible. Alternatively, in "normal mode" the vehicle is driven
only by the electric motor 5 or by a combination of the electric
motor and the internal combustion engine.
[0033] Additionally or alternatively to step S9a, in step S9b it is
determined how much time has elapsed since the determination of the
need to heat the exhaust gas aftertreatment system 15, i.e. for
example since a cold start. The determined time value is compared
with a specifiable time interval. If the determined time value is
less than the specified time interval, then steps S5 and S7 are
repeated. If the determined time value is equal to or greater than
the specified time interval, then the dragging process is
terminated and the normal driving mode is initiated.
[0034] Another additional or alternative step S9c can be provided.
In step S9c a check is carried out as to whether the battery of the
electric motor 5 still has sufficient energy to be able to continue
the process. In the event that there is sufficient energy the
process is continued and steps 55 and S7 are repeated. If
sufficient energy is no longer available, then a change is made to
the normal driving mode using the internal combustion engine 3.
[0035] The described method can be combined with other heating
measures, such as for example catalyzer heating measures. For
example, in addition optimization of the working temperature can
take place by configuring the position and the distribution of the
individual injection quantities for the exhaust gas temperature.
Said additional method for adjusting the optimal temperature of the
exhaust gas aftertreatment system is referred to as HSP (Homogenous
Split).
[0036] In FIG. 2 a hybrid vehicle system with a control unit 1 is
illustrated schematically, which is suitable for carrying out the
method described above. The hybrid vehicle system comprises,
besides the control device 1, an internal combustion engine 3 and
an electric motor 5. The internal combustion engine 3 and the
electric motor 5 can be connected to each other by means of a
clutch 11. An exhaust gas aftertreatment system 15 is connected to
the internal combustion engine 3. The exhaust gas aftertreatment
system 15 comprises a catalyzer 17. A lambda probe 19 is also
provided before the exhaust gas aftertreatment system. The hybrid
vehicle system also comprises a converter 9, an automatic gearbox 7
and an axle with vehicle wheels 13. The control device 1 can be
connected to all the mentioned components of the hybrid vehicle
system and can control or regulate them. In particular, the control
device 1 can determine the current temperature value of the exhaust
gas aftertreatment system 15 or of the lambda probe 19. The control
device 1 can also regulate the injection and ignition parameters of
the internal combustion engine 3 and can adjust or regulate the
revolution rates of the internal combustion engine 3 and of the
electric motor 5.
[0037] The control device 1 is designed to control the electric
motor 5 such that it drags the internal combustion engine 3
following a cold start and thereby maintains it at a specifiable
revolution rate. In this way the hot exhaust gases of the internal
combustion engine 3 rapidly bring the exhaust gas aftertreatment
system 15 to an optimal working temperature as required. This
enables the C02 emissions to be reduced.
[0038] In conclusion it is noted that expressions such as "having"
or similar should not exclude the ability to provide other elements
or steps. Furthermore, it should be noted that "one" does not
exclude any number. Moreover, connections with the various
embodiments of described features can be combined as desired.
* * * * *