U.S. patent application number 12/948283 was filed with the patent office on 2011-05-19 for exhaust gas aftertreatment device.
This patent application is currently assigned to Robert Bosch GMBH. Invention is credited to Patrick Bauer, Ralph Bauer, Georg Hoegele, Thomas Holst, Mehmet Oencel, Bernd Schelling.
Application Number | 20110113768 12/948283 |
Document ID | / |
Family ID | 43877455 |
Filed Date | 2011-05-19 |
United States Patent
Application |
20110113768 |
Kind Code |
A1 |
Bauer; Patrick ; et
al. |
May 19, 2011 |
EXHAUST GAS AFTERTREATMENT DEVICE
Abstract
The invention relates to an exhaust gas aftertreatment device
(1) of a motor vehicle, said device having a heater (2), which
includes a plurality of heating elements (5, 6, 7), and a control
unit (9) associated with the heater (2), wherein a common first
switch (10) and in each case a second switch (32, 33, 34) are
associated with the heating elements (5, 6, 7) and said heating
elements (5, 6, 7) are jointly switchable by means of the first
switch (10) and individually switchable by means of the second
switches (32, 33, 34). The invention thereby provides that said
first switch (10) is disposed separately from the control unit (9)
and can be actuated by the same.
Inventors: |
Bauer; Patrick; (Stuttgart,
DE) ; Oencel; Mehmet; (Boennigheim, DE) ;
Bauer; Ralph; (Esslingen, DE) ; Schelling; Bernd;
(Stuttgart, DE) ; Holst; Thomas; (Stuttgart,
DE) ; Hoegele; Georg; (Muenchingen, DE) |
Assignee: |
Robert Bosch GMBH
Stuttgart
DE
|
Family ID: |
43877455 |
Appl. No.: |
12/948283 |
Filed: |
November 17, 2010 |
Current U.S.
Class: |
60/320 |
Current CPC
Class: |
F01N 3/027 20130101;
Y02T 10/12 20130101; Y02T 10/26 20130101; Y02A 50/20 20180101; F01N
3/202 20130101; Y02A 50/2322 20180101; F01N 3/2013 20130101; F01N
2390/02 20130101 |
Class at
Publication: |
60/320 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 17, 2009 |
DE |
10 2009 046 769.6 |
Claims
1. Exhaust gas aftertreatment device of a motor vehicle, said
device having a heater, which includes a plurality of heating
elements, and a control unit associated with the heater, wherein a
common first switch and in each case a second switch are associated
with the heating elements and said heating elements are jointly
switchable by means of the first switch and individually switchable
by means of the second switches, wherein said first switch is
disposed separately from the control unit and can be actuated by
the same.
2. Exhaust gas aftertreatment device according to claim 1, wherein
at least a portion of the second switches is provided in the
control unit or is likewise disposed separately from said control
unit and can be actuated by the same.
3. Exhaust gas aftertreatment device according to claim 1, wherein
the first switch (10) is provided between the heating elements and
a positive pole of a direct current source.
4. Exhaust gas aftertreatment device according to claim 1, wherein
the second switches are provided between the heating elements and a
negative pole or between the first switch and said heating
elements.
5. Exhaust gas aftertreatment device according to claim 1, wherein
the first switch and/or the second switches are relays or
electronic assemblies.
6. Exhaust gas aftertreatment device according to claim 1, wherein
a diagnostic device is associated with the first switch and/or at
least a portion of the second switches and/or at least a portion of
the heating elements.
7. Exhaust gas aftertreatment device according to claim 1, wherein
the diagnostic device is connected to the control unit or is formed
by the same.
8. Exhaust gas aftertreatment device according to claim 1, wherein
the control unit is adapted to actuate the first switch so as to
switch off the heating elements in the event that an error
occurs.
9. Exhaust gas aftertreatment device according to claim 1, wherein
the control unit is connected to the same power source as the
heater or to a separate power source.
10. Exhaust gas aftertreatment device according to claim 1, wherein
an overvoltage protection device is provided between the power
source and the control unit and/or the heating elements.
Description
[0001] This application claims benefit of Serial No. 10 2009 046
769.6, filed 17 Nov. 2009 in Germany and which application is
incorporated herein by reference. To the extent appropriate, a
claim of priority is made to the above disclosed application.
BACKGROUND
[0002] The invention relates to an exhaust gas aftertreatment
device of a motor vehicle having a heater, which includes a
plurality of heating elements, and a control unit associated with
the heater. A common first switch and in each case a second switch
are associated with the heating elements and said heating elements
can be jointly switched by means of the first switch and
individually switched by means of the second switch.
[0003] Exhaust gas aftertreatment devices of the type mentioned
above are known from prior art. They are frequently used in the
commercial vehicle sector. The heater is supplied with current via
a main path, which can be switched via the first switch. The
individual heating elements of the heater can also be individually
switched via the second switch, which in each cased is associated
with them. The first switch and the second switches are thereby
normally disposed in the control unit associated with the heater.
The heater, respectively the heating elements are therefore
supplied with current via said control unit as soon as the first
switch and the respective second switch are closed. In doing so,
the heating elements can only then be switched on by means of the
second switches if the first switch is closed. For this reason, the
first switch is connected in series with the heater and the second
switches are in each case connected in series with the individual
heating elements. As a result, the first switch and the second
switches are embodied as electrical switches. A method for
controlling an electrical heater of a catalytic converter for the
exhaust gas purification of an internal combustion engine in a
motor vehicle is known from the German patent specification DE 44
22 198 A1. Two batteries are thereby provided; both of which can be
connected to the electrical heater. In so doing, provision is made
for the batteries to be decoupled from each other before switching
on the heater, so that a load is being placed on only one of said
batteries while the other battery can continue to supply an
electrical system of the vehicle. A disadvantage of the exhaust gas
aftertreatment of prior art is that in each case a power loss is
incurred at the first switch and the second switches. For this
reason, the control unit, in which the switches are normally
disposed, must be designed accordingly. A large power loss is
incurred particularly at the first switch because the heater and
hence all heating elements are supplied with current via said
switch.
SUMMARY
[0004] In contrast, the exhaust gas aftertreatment device with the
features of claim 1 has the advantage that the power loss incurred
in the control unit is significantly smaller than that from prior
art. The inventive device achieves this objective by the first
switch being disposed separately from the control unit and being
actuated by the same. Said control unit can in this way be designed
with smaller dimensions because a cooling device for said first
switch is eliminated. The cooling device is, for example, a passive
heat sink and/or an active cooling system, which particularly
comprises a fan. Said first switch can furthermore be actuated by
said control unit. A cable is especially provided for this purpose
between said control unit and said first switch. Said first switch
can be advantageously implemented by means of an electronic or
mechanical relay. This relay is triggered by said control unit,
whereby it is assured that the heater can be quickly switched off
should a malfunction of the heater and/or said control unit be
detected. It is for this reason advantageous if said first switch
is open in an initial position and is first brought into a
switching position, in which said first switch is closed, by a
corresponding actuation by means of the control unit. As soon as
said first switch is no longer actuated by said control unit, it
advantageously returns to its initial position whereby the heater
is switched off.
[0005] Provision is made in a modification to the invention for at
least a portion of the second switches to be provided in the
control unit or likewise to be disposed separately from said
control unit and to be capable of being actuated by the same.
Provision can therefore be made for said second switches to be
disposed at said control unit while the first switch is arranged
separately therefrom. As an alternative, it is possible to also
dispose the second switches or at least a portion of the same
separately from said control unit and to actuate them via the same.
In the case of such an embodiment of the exhaust gas aftertreatment
device, the power loss, which is incurred in said control unit, can
be further reduced. It is especially possible for a separate
current supply to be provided for the control unit; thus enabling
control unit and heater to be supplied by power sources which are
independent of one another. Because the current flowing through the
heater is not conveyed by said control unit, it is possible to
design said heater for currents, which could not be realized if the
current were directly supplied via said control unit. This also
likewise means that said control unit can be constructed even
smaller because cables and terminals of said control unit merely
have to be matched to reduced currents.
[0006] Provision is made in a modification to the invention for the
first switch to be provided between the heating elements and a
positive pole of a direct current source. Said first switch is
therefore embodied as a so-called high-side switch. The heater,
respectively the heating elements, can thus be separated from the
positive pole via said first switch. This is particularly
advantageous if a short circuit is present in said heater because a
stress on the direct current source as a result of the short
circuit can be avoided.
[0007] Provision is made in a modification to the invention for the
second switches to be provided between the heating elements and a
negative pole or between the first switch and the heating elements.
If the former is the case, the second switches are configured as
low-side switches. This has the advantage that a simpler actuation
of the switch is possible, for example, when using an electronic
switch (transistor or the like). If on the other hand the second
switches are disposed between the first switch and the heating
elements, said second switches also form high-side switches and are
therefore able to directly separate the heating elements from the
positive pole of the direct current source.
[0008] A modification to the invention provides that the first
switch and/or the second switches are relays or electronic
assemblies. The switches can basically be arbitrarily embodied. It
is, however, advantageous if said first and/or said second switches
are embodied in particular as mechanical relays or as electronic
assemblies. The electronic assembly has, for example, a transistor
or a similar switching unit, which can be actuated by the control
unit.
[0009] A modification to the invention provides for a diagnostic
device to be associated with the first and/or at least a second
portion of the second switches and/or at least a portion of the
heating elements. A defect in the switches and/or the heating
elements can, for example, be detected by means of the diagnostic
device. If a defect is present, suitable measures can then be
taken. The first switch, for example, is opened so that the heater
is turned off. Provision can be made, however for said diagnostic
device to detect a switching state of the first and/or the second
switch and to make this information available to the control unit.
In order to meet this objective, said diagnostic device is
connected to said control unit by means of circuitry.
[0010] A modification to the invention provides that the diagnostic
device is connected to the control unit or is formed from the same.
In the former case, said diagnostic device is, for example,
disposed in the region of the first switch, the second switch
and/or the heater. In so doing, it is connected to said control
unit in order to provide the same with feedback about the operating
status of the exhaust gas aftertreatment device, for example, the
operating status of switches, the heater and/or individual heating
elements. Said diagnostic device can, however, also be formed from
said control unit, respectively be an integral part thereof. In
this case, a sensor, the sensor values of which are evaluated by
said diagnostic device, can in each case be associated with the
component to be diagnosed, hence the first switch, the second
switches, the heater and/or the heating elements.
[0011] A modification to the invention provides for the control
unit to be designed in such a way that the first switch is actuated
to turn off the heating elements when an error occurs. The
occurrence of the error is, for example, detected by the diagnostic
device. In order to avoid damage to the exhaust gas aftertreatment
device, the heater is turned off by the heating elements being
deactivated. For this purpose, the first switch is opened by the
control unit by appropriate actuation. Said first switch is
configured for the purpose of turning off the heating elements as
soon as an actuation of said switch does not occur.
[0012] A modification to the invention provides that the control
unit is connected to the same power source as the heater or to a
separate power source. As previously mentioned, the heater is
connected to the same power source as the control unit if only the
first switch is disposed separately from said control unit. If the
second switches are additionally provided outside of said control
unit, said control unit can then be connected to a separate power
source. In this way, said control unit can, for example, be
operated with a different supply voltage than the heater.
[0013] Provision is made in a modification to the invention for an
overvoltage protection device to be provided between the power
source and the control unit and/or the heating elements. In order
to protect said control unit, respectively said heating elements,
from too high a voltage, the overvoltage protection device is
provided in the exhaust gas aftertreatment device. Said overvoltage
protection device can, for example, be provided by circuitry means
between the positive pole of the dc current source and the first
switch. Said overvoltage protection device can be a voltage filter
or alternatively interrupting means, which separate the power
source from said control unit, respectively the heating elements,
as soon as being subjected to an overvoltage. Said overvoltage is
thereby a voltage, which is greater than a certain maximum
voltage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention is subsequently explained in detail with the
aid of the exemplary embodiments depicted in the drawing. No
limitation to the invention results from the explanation of said
embodiments. The following are shown:
[0015] FIG. 1 is a region of a first embodiment of an exhaust gas
aftertreatment device, and
[0016] FIG. 2 is a region of a second embodiment of the exhaust gas
aftertreatment device.
DETAILED DESCRIPTION
[0017] FIG. 1 shows a region of an exhaust gas aftertreatment
device 1 of an unspecified motor vehicle. The exhaust gas
aftertreatment device 1 comprises, for example, a heater 2 having
five heating elements 3, 4, 5, 6 and 7 and a switching valve 8. The
heating elements 3, 4, 5, 6, and 7 are, for example, embodied as
heating wires, filaments or the like, while an unspecified coolant
circuit for removing heat from the heating elements 3 to 7 can be
released, respectively interrupted, by the switching valve 8. The
heater 2 can be associated with an SCR system, wherein it serves to
heat at least one pipeline, through which an operating means (for
example a water-urea solution) is supplied to a catalytic converter
(unspecified). A water-urea solution that is typically used freezes
at approximately -10EC so that at low outside temperatures a
heating of the pipeline by means of the heater 2 is necessary to
thaw the water-urea solution, respectively maintain the liquid
state of said solution. The heat of at least one of the heating
elements 3 to 7 is supplied to the pipeline via the coolant
circuit. In order to meet this objective, the heater 2 is activated
by a control unit 9 assigned thereto.
[0018] Furthermore, a first switch 10 is provided, which can be
actuated by the control unit 9 via an actuator 11. For this
purpose, the actuator 11 is connected to said control unit 9 via
cables 12 and 13. The cable 12 is connected to cables 14 and 15,
which can be connected to a positive pole 17 of a direct current
source, which is not specified here. The switch 16 serves thereby
as a so-called high-side switch for said actuator 11, the heating
element 3 as well as the switching valve 8, which are connected to
the switch 16 via the cables 12, and 14. The heating element 4 can
be connected to the positive pole 17 via an additional switch 18
and a cable 19. Also the switch 18 is accordingly embodied as a
high-side switch. Said actuator 11 can be connected to a negative
pole 21 of the direct current source via the cable 13 and a switch
20. This is likewise true for the heating element 3 via a switch 22
and a cable 23 and for the switching valve 8 via a switch 24 and a
cable 25.
[0019] The actuator 11 can only then be activated if the switch 16
as well as the switch 20 is closed so that said actuator 11 is
connected to the positive pole 17 as well as to the negative pole
21. This also applies analogously to the heating element 3 and the
switching valve 8; and in so doing the switch 22, respectively the
switch 24, has to be closed. The heating element 4 can be connected
to the positive pole 17 as well as to the negative pole 21 and
thereby be activated by closing both the switch 18 and a switch 26,
which is connected to the heating element 4 via a cable 27.
[0020] The first switch 10, which can be actuated by means of the
actuator 11, serves as a high-side switch for the heating elements
5, 6 and 7. These can consequently be connected to the positive
pole 17 by closing said switch 10, which is provided via actuation
of the actuator 11 by the control unit 9. For this purpose, the
first switch 10 is connected to the heating elements 5, 6 and 7 via
a common cable 28. On the side of said heating elements 5, 6 and 7
which faces away from said first switch 10, said heating elements
5, 6 and 7 are connected to the second switches 32, 33 and 34 via
cables 29, 30 and 31. Said second switches 32, 33, and 34 serve as
low-side switches for said heating elements 5, 6 and 7; thus they
can establish a connection to the negative pole 21.
[0021] It can be seen that the heating elements 5, 6 and 7 are
jointly switchable via the first switch 10 and are individually
switchable via the second switches 32, 33, and 34. In this
exemplary embodiment, said first switch 10 is thereby disposed
outside of the control unit 9, respectively separated from the
same, can, however, still be actuated by said control unit 9. The
actuator 11, as already described, is provided for this purpose.
The second switches 32, 33, and 34 are likewise actuated by said
control unit 9; however--in contrast to said first switch 10--are
disposed therein. It is then obvious that said first switch 10 is
provided between the heating elements 5, 6 and 7 and the positive
pole 17 and said second switches 32, 33, 34 are provided between
said heating elements 5, 6 and 7 and the negative pole 21. Said
first switch 10 is thereby embodied as a mechanical relay, which is
actuated, respectively switched, by means of the actuator 11. As a
result, said actuator 11 can, for example, be a magnetic actuator.
Said second switches 32, 33 and 34 are preferably embodied as
electronic components, for example, as transistors (or MOSFET),
respectively power transistors. By means of the external disposal
of said first switch 10, the power loss incurred in said control
unit 9 can be significantly reduced. In the case depicted here,
said control unit 9 and the heater 2 are connected to the same
power supply.
[0022] FIG. 2 shows a further embodiment of the exhaust gas
aftertreatment device 1, wherein again merely a cut-out is
depicted. Only the heating elements 5, 6 and 7 are depicted for
this embodiment, which are jointly switchable by means of the first
switch 10 and individually, respectively separately, switchable by
means of the second switches 32, 33 and 34. Said first switch 10 is
in turn actuated by the control unit 9 via the actuator 11. For
that purpose, said actuator 11 is connected to said control unit 9
via the cables 12 and 13. Said cables 12 and 13 can be connected to
a positive pole 35 via the switch 16 and to a negative pole 36 via
the switch 20 of a separate power source not depicted here, in
particular a direct current source. The power supply of the heating
elements 5, 6 and 7 is on the other hand still implemented via the
positive pole 17 and the negative pole 21. For that purpose, said
first switch 10 as well as said second switches 32, 33, and 34 is
disposed between said heating elements 5, 6 and 7 and the positive
pole 17. Said first switch 10 as well as said second switches 32,
33, 34 are accordingly embodied as high-side switches for said
heating elements 5, 6 and 7. Said heating elements 5, 6 and 7 are
connected directly to the negative pole 21 of the direct current
source on the side facing away from said second switches 32, 33,
and 34.
[0023] The second switches 32, 33, and 34 are connected to the
control unit 9 via the cables 37, 38 and 39 and can be connected
here to the negative pole 36 via the switches 40, 41 and 42. Said
second switches 32, 33 and 34 are thereby embodied, for example, as
transistors; thus enabling them to become electrically conductive
when the first switch 10 is closed and when switches 40, 41 and 42
are in each case closed and as a result switch on the heating
elements 5, 6 and 7. In this embodiment, the first switch 10 as
well as the second switches 32, 33 and 34 are disposed outside of,
respectively separately from, the control unit and can be actuated
by the same. That means that the power loss incurred in the control
unit 9 can be further reduced in comparison to the embodiment of
FIG. 1. Furthermore, separate power sources for said control unit 9
and the heater 2 can be advantageously provided.
[0024] In the embodiment depicted, the heater 2 is connected to the
direct current source and the control unit 9 to the separate direct
current source. Thus, the heating elements 5, 6 and 7 can, for
example, be supplied with a higher operating voltage than said
control unit 9. In addition, an unspecified protection device can
be provided. This is preferably disposed between the positive pole
17 and the first switch 10. The protection device protects said
heating elements 5, 6 and 7 from the occurrence of current pulses
which are too high or from overvoltage, respectively voltage
pulses, which could lead to damage to said elements.
* * * * *