U.S. patent application number 13/704665 was filed with the patent office on 2013-05-02 for method and device pertaining to cooling of dosing units of scr systems.
The applicant listed for this patent is Per Bremberg, Ulf Carlsson, Lars Eriksson, Andreas Liljestrand. Invention is credited to Per Bremberg, Ulf Carlsson, Lars Eriksson, Andreas Liljestrand.
Application Number | 20130104527 13/704665 |
Document ID | / |
Family ID | 45371667 |
Filed Date | 2013-05-02 |
United States Patent
Application |
20130104527 |
Kind Code |
A1 |
Liljestrand; Andreas ; et
al. |
May 2, 2013 |
METHOD AND DEVICE PERTAINING TO COOLING OF DOSING UNITS OF SCR
SYSTEMS
Abstract
A method for cooling a dosing unit (250) pertaining to an SCR
system for exhaust cleaning: after cessation of exhaust flow,
cooling a reducing agent dosing unit (250) by reducing agent
supplied to the unit. Intermittently running a feed device (230) to
supply reducing agent, and running the feed device (230) at reduced
power compared with its ordinary operation. Also a computer
programme product containing programme code (P) for a computer
(200; 210) for implementing the method. Also an SCR system and a
motor vehicle (100; 110) which is equipped with the SCR system are
disclosed
Inventors: |
Liljestrand; Andreas;
(Sodertalje, SE) ; Bremberg; Per; (Sodertalje,
SE) ; Carlsson; Ulf; (Sodertalje, SE) ;
Eriksson; Lars; (Jarna, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Liljestrand; Andreas
Bremberg; Per
Carlsson; Ulf
Eriksson; Lars |
Sodertalje
Sodertalje
Sodertalje
Jarna |
|
SE
SE
SE
SE |
|
|
Family ID: |
45371667 |
Appl. No.: |
13/704665 |
Filed: |
June 20, 2011 |
PCT Filed: |
June 20, 2011 |
PCT NO: |
PCT/SE2011/050789 |
371 Date: |
January 16, 2013 |
Current U.S.
Class: |
60/274 ;
60/286 |
Current CPC
Class: |
F01N 9/00 20130101; F01N
3/04 20130101; F01N 2610/02 20130101; F01N 2610/11 20130101; F01N
2610/1473 20130101; Y02T 10/24 20130101; F01N 2610/1453 20130101;
F01N 2900/1812 20130101; Y02T 10/40 20130101; Y02T 10/47 20130101;
F01N 3/208 20130101; Y02A 50/20 20180101; Y02T 10/12 20130101; Y02A
50/2325 20180101 |
Class at
Publication: |
60/274 ;
60/286 |
International
Class: |
F01N 3/04 20060101
F01N003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2010 |
SE |
1050639-2 |
Claims
1. A method for cooling a dosing unit pertaining to an SCR system
for exhaust cleaning for a combustion engine having an exhaust flow
when the engine is operating, a reducing agent dosing unit located
generally at the exhaust flow; the method comprising the steps of:
operating the engine having the exhaust flow; then halting
operation of the engine having the exhaust flow and thereby ceasing
the exhaust flow; after cessation of exhaust flow, cooling the
reducing agent dosing unit by supplying a reducing agent to the
dosing unit; intermittently running a feed device to supply said
coolant reducing agent, and running said feed device at reduced
power compared with power at which said feed device is run during
ordinary operation of said feed device.
2. A method according to claim 1, further comprising running said
feed device intermittently with a predetermined interval
configuration.
3. A method according to claim 2, wherein said predetermined
interval configuration is selected for catering for rewarming
effects of said dosing unit.
4. A method according to claim 1, further comprising intermittently
activating operation of said feed device based on a measured
temperature of at least one portion of said SCR system.
5. A method according to claim 1, wherein said feed device is
operated to cool said dosing unit to a temperature below a
predetermined limit value.
6. A method according to claim 1, wherein said reducing agent is a
fluid solution which contains urea.
7. An SCR system for a combustion engine having an exhaust flow
when said engine is operating for exhaust cleaning, the system
comprises: a coolable reducing agent dosing unit located generally
at the exhaust flow; a cooling device operable after cessation of
exhaust flow from the engine for cooling said reducing agent dosing
unit by supplying reducing agent to said dosing unit; and a control
device for intermittently running said feed device to supply said
coolant reducing agent, and said feed device is configured and
operable to run at reduced power during intermittent running as
compared with power at which said feed device is run during
ordinary operation of said feed device.
8. An SCR system according to claim 7, wherein said feed device is
run intermittently with a predetermined interval configuration.
9. An SCR system according to claim 8, wherein said predetermined
interval configuration is selected for catering for rewarming
effects of said dosing unit.
10. An SCR system according to claim 7, wherein said feed device is
configured to be activated based on a measured temperature of at
least one portion of said SCR system.
11. An SCR system according to claim 7, wherein said feed device,
when operating, is configured and operable to cool said dosing unit
to a temperature below a predetermined limit value.
12. An SCR system according to claim 7, wherein said reducing agent
is a fluid solution which contains urea.
13. A motor vehicle comprising an SCR system according to claim
7.
14. A motor vehicle according to claim 13, comprising a truck, bus
or passenger car.
15. A computer programme pertaining to an SCR reducing agent system
for exhaust cleaning of an engine which generates exhaust during
operation, wherein said dosing system comprises a dosing unit for
reducing agent, and wherein said programme product comprises
non-transitory programme code with non-transitory programme
instructions for causing a computer system to perform steps on an
electronic control unit or causing another computer connected to
the electronic control unit to perform steps according to claim 1
when instructions in said code are run on said computer system.
16. A computer programme product according to claim 15, wherein the
product contains a programme code stored on a non-transitory
computer-readable medium which can be read by said computer system
for performing method steps, wherein said computer programme is run
on an electronic control unit or another computer connected to
electronic control unit
Description
TECHNICAL FIELD
[0001] The present invention relates to a method pertaining to an
SCR system for exhaust cleaning. The invention relates also to a
computer programme product containing programme code for a computer
for implementing a method according to the invention. The invention
relates also to an SCR system for exhaust cleaning and a motor
vehicle which is equipped with the SCR system.
BACKGROUND
[0002] Vehicles today use, for example, urea as reductant in SCR
(selective catalytic reduction) systems which comprise an SCR
catalyst in which said reductant and NOx gas can react and be
converted to nitrogen gas and water. Various types of reductants
may be used in SCR systems. AdBlue is an example of a commonly used
reductant.
[0003] One type of SCR system comprises a container which holds a
reductant. The SCR system has also a pump adapted to drawing said
reductant from the container via a suction hose and to supplying it
via a pressure hose to a dosing unit situated adjacent to an
exhaust system of the vehicle, e.g. adjacent to an exhaust pipe of
the exhaust system. The dosing unit is adapted to injecting a
necessary amount of reductant into the exhaust pipe upstream of the
SCR catalyst according to operating routines which are stored in a
control unit of the vehicle. To make it easier to regulate the
pressure when there are small or no dosing amounts, the system also
comprise a return hose which runs back to the container from a
pressure side of the system. This configuration makes it possible
to cool the dosing unit by means of the reductant which, during
cooling, flows from the container via the pump and the dosing unit
and back to the container. The dosing unit is thus provided with
active cooling. The return flow from the dosing unit to the
container may be substantially constant and is currently not
controlled or regulated by means of appropriate valves or such
units.
[0004] As the dosing unit is currently situated adjacent to the
vehicle's exhaust system which becomes warm during operation of the
vehicle, e.g. depending on the load, there is risk of the dosing
valve becoming overheated. Overheating of the dosing unit may
entail degradation of its functionality, potentially impairing its
performance.
[0005] The dosing unit currently comprises electrical components,
certain of them being provided with a circuit card. Said circuit
card may for example be adapted to controlling the dosing of AdBlue
to the vehicle's exhaust system. For various reasons, these
electrical components are sensitive to high temperatures. Too high
temperatures of the dosing unit may result in degradation of the
electrical components, potentially leading to expensive repairs at
a service workshop. Moreover, the reductant present in the dosing
unit may at least partly crystallise at too high temperatures,
potentially leading to obstruction of the dosing unit. It is
therefore of the utmost importance that the temperature of the
dosing unit of the SCR system should not exceed a critical
level.
[0006] Cooling the dosing unit of a vehicle's SCR system currently
takes place continuously during the vehicle's ordinary operation as
a result of the reductant circulating within the SCR system as
indicated above. Cooling the dosing unit during operation of the
vehicle currently works satisfactorily.
[0007] After operation of the vehicle a large amount of thermal
energy caused by its operation is stored in primarily the exhaust
system. This thermal energy may be led to the dosing unit from, for
example, a silencer and the SCR catalyst and may warm the dosing
unit to a temperature which exceeds a critical value.
[0008] When the vehicle is switched off and the exhaust flow in the
exhaust system consequently ceases, the reductant dosing unit is
cooled for a predetermined time, e.g. about 30 minutes, by said
reductant in the same way as during ordinary operation.
[0009] This arrangement entails certain disadvantages. One is a
relatively large amount of energy used to power the pump in the SCR
system after the vehicle has been switched off. Any vehicle battery
used to power the pump of the SCR system might thus be discharged
or reach an undesirably low charge level.
[0010] Another disadvantage of the dosing unit being cooled in the
same way as during ordinary operation is that the pump of the SCR
system emits disturbing noise which for example a driver of the
vehicle may find irritating, particularly when he/she has to sleep
in the cab after a driving run or is in the immediate vicinity of
the vehicle.
[0011] There is thus a need to improve current methods for cooling
the dosing unit in the SCR system after the vehicle has been
switched off, in order to reduce or eliminate the above
disadvantages.
[0012] DE 102007000666 A1 refers to a device for supply of reducing
agent to an exhaust duct during catalytic exhaust cleaning and
discusses cooling of an injection valve for reducing agent after
the engine and consequently the exhaust flow have been switched
off. The arrangement in DE 102007000666 A1 comprises a cooling
jacket which for cooling purposes surrounds the injection valve and
is adapted to having reducing agent flow through it. The primary
focus here is on the temperature of the reducing agent, mainly by
measurement.
SUMMARY OF THE INVENTION
[0013] An object of the present invention is to propose a novel and
advantageous method for improving the performance of an SCR
system.
[0014] Another object of the present invention is to propose a
novel and advantageous SCR system and a novel and advantageous
computer programme for improving the performance of an SCR
system.
[0015] An object of the present invention is to propose a novel and
advantageous method for effecting cooling of a dosing unit of an
SCR system after cessation of an exhaust flow therein.
[0016] Another object of the invention is to propose a novel and
advantageous SCR system and a novel and advantageous computer
programme for effecting cooling of a dosing unit of an SCR system
after cessation of an exhaust flow in the SCR system.
[0017] A further object of the invention is to propose a method,
SCR system and a computer programme for reducing the risk that a
dosing unit in an SCR system might become overheated after
cessation of an exhaust flow in the SCR system.
[0018] A further object of the invention is to propose an
alternative method, an alternative SCR system and an alternative
computer programme for reducing the risk that a dosing unit in an
SCR system might become overheated after cessation of an exhaust
flow in the SCR system.
[0019] These objects are achieved with a method pertaining to SCR
systems for exhaust cleaning according to claim 1.
[0020] An aspect of the invention proposes a method for cooling a
dosing unit pertaining to SCR systems for exhaust cleaning,
comprising, after cessation of exhaust flow, the steps of cooling a
reducing agent dosing unit by means of reducing agent supplied to
it, and of intermittently running a feed device to supply said
coolant reducing agent at reduced operating power compared with
ordinary operation.
[0021] Intermittently running the feed device for said reducing
agent results in a functionality of the SCR system which reduces or
minimises the impact of the SCR system. The feed device may be run
intermittently at an operating power which achieves desirable
cooling of the dosing unit. The feed device may be run
intermittently at reduced power compared with ordinary operation.
This results in positive synergy effects according to the
innovative method, e.g. a substantial reduction in energy
consumption involved in the cooling process.
[0022] The feed device may be run intermittently with a
predetermined interval configuration. This predetermined interval
configuration may be defined as operation of the feed device being
deactivated at certain periodicities and being subsequently
reactivated.
[0023] This sequence of temporary deactivation and reactivation may
be repeated until the dosing unit of the SCR system has reached a
predetermined desirable temperature, e.g. 40 degrees Celsius.
[0024] This predetermined interval configuration may entail
catering for rewarming effects of said dosing unit. As the dosing
unit according to certain versions is fitted adjacent to an exhaust
system which comprises for example an SCR catalyst and other
components which may transfer stored thermal energy to the dosing
unit, even after the latter has been cooled to a desirable
temperature, it is advantageous to cater for these rewarming
effects when determining said interval configuration.
[0025] Operation of the feed device may be activated on the basis
of a measured temperature of at least one portion of said SCR
system.
[0026] Operation of the feed device may result in cooling of said
dosing unit to a temperature which is below a predetermined limit
value.
[0027] Said reducing agent may be a fluid solution which contains
urea, e.g. AdBlue.
[0028] To minimise the impact upon the vehicle, a proposed function
causes operation of the pump of the feed device of the SCR system
to be deactivated and reactivated any desired number of times
during cooling of the dosing unit after the cessation of said
exhaust flow. According to a version, the pump speed is lower or
substantially lower than that employed during ordinary operation of
the SCR system, which ordinary operation comprises operation of the
SCR system when the vehicle is in motion, or previous ordinary
operation of the SCR system during cooling of the dosing unit after
the cessation of said exhaust flow.
[0029] With advantage, a previous need for electrical energy from a
battery of the vehicle when its engine is off during the subsequent
cooling procedure is reduced.
[0030] Maintaining intermittent operating power of the feed device,
with substantially unchanged cooling power of the dosing unit,
results in less noise than running the feed device at full power as
previously. Part of the inventiveness of the present invention is
that it has been found that the cooling power of the dosing unit is
reduced only marginally when the feed device is run
intermittently.
[0031] Applying reduced operating power of the feed device, with
substantially unchanged cooling power of the dosing unit, results
in less noise than running the feed device at full power as
previously.
[0032] Despite the operating power of the feed device being reduced
compared with ordinary operation and despite its being run
intermittently, with substantially unchanged cooling power of the
dosing unit, it is possible to avoid the reducing agent becoming
crystallised as a result of too high temperatures and thereby
causing obstruction of the dosing unit, potentially leading to
expensive repairs of the SCR system.
[0033] By reducing the operating power of the feed device, with
substantially unchanged cooling power of the dosing unit,
temperature-related damage to the dosing unit's electrical
components may with advantage be prevented.
[0034] Despite the feed device being run intermittently, with
substantially unchanged cooling power of the dosing unit,
temperature-related damage to the dosing unit's electrical
components may with advantage be prevented.
[0035] Reducing the operating power of the feed device may entail
running it at a lower speed than during ordinary operation.
Reducing the power of the feed device may result in a lower
pressure of the reducing agent towards the dosing unit than during
ordinary operation.
[0036] According to an embodiment, the power of the feed device for
said reducing agent is reduced in at least one stage to a level
which results in substantially no change in the cooling power of
the dosing unit but uses substantially less energy than in the
state of the art.
[0037] The method may comprise the step of intermittently running
said feed device at least possible power, with substantially
unchanged cooling power of said dosing unit, for as long as cooling
continues. With advantage, a cooling function is achieved whereby
the cooling power of said dosing unit is substantially unchanged
but the impact of the SCR system is decreased in a desirable
way.
[0038] The step of running said feed device may comprise running it
at a power corresponding to 10-30% of that during ordinary
operation. With advantage, this results in a substantially
reduction in the amount of energy required for adequate cooling of
the dosing unit of the SCR system, particularly since the feed
device is also run intermittently. According to a preferred
embodiment, the step of running said feed device may comprise
running it at a power corresponding to less than 10% of that during
ordinary operation. According to an embodiment, the innovative
method may result in a total energy saving of 10-50% compared with
cooling methods according to the state of the art.
[0039] The method may further comprise the step of running said
feed device on the basis of a measured temperature of at least one
portion of said SCR system. Any adequate temperature of said at
least one portion of said SCR system may be used such that cooling
of the dosing unit can be switched off automatically when said
temperature of the at least one portion of said SCR system is
reached after cessation of the exhaust flow.
[0040] Running said feed device may entail catering for rewarming
effects. Said predetermined period of time and said adequate
temperature of the at least one portion of said SCR system may be
predetermined by a computer model stored in a control unit of the
vehicle on the basis of already known rewarming effects of the SCR
system. The rewarming effects may be determined on the basis of
predicted thermal energy storage in the SCR system.
[0041] The method is easy to implement in existing motor vehicles.
Software pertaining to an SCR system for exhaust cleaning according
to the invention may be installed in a control unit of the vehicle
during the manufacture of the vehicle. A purchaser of the vehicle
may thus have the possibility of selecting the function of the
method as an option. Alternatively, software which comprises
programme code for applying the innovative method pertaining to an
SCR system for exhaust cleaning may be installed in a control unit
of the vehicle on the occasion of upgrading at a service station,
in which case the software may be loaded into a memory in the
control unit. Implementing the innovative method is therefore
cost-effective, particularly since the vehicle need not be provided
with any further components or subsystems. Relevant hardware is
currently already provided in the vehicle. The invention therefore
represents a cost-effective solution to the problems indicated
above.
[0042] Software comprising programme code for, after cessation of
an exhaust flow, cooling a reducing agent dosing unit by means of
reducing agent supplied to it, and for intermittently running a
feed device to supply said coolant reducing agent and running said
feed device at reduced power compared with ordinary operation,
according to an aspect of the invention, is easy to update or
replace. Moreover, various parts of the software containing
programme code for applying the innovative method may be replaced
independently of one another. This modular configuration is
advantageous from a maintenance perspective.
[0043] An aspect of the invention proposes an SCR system for
exhaust cleaning which comprises a coolable dosing unit, comprising
means for, after cessation of exhaust flow, cooling a reducing
agent dosing unit by means of reducing agent intended to be
supplied to it, and means for intermittently running a feed device
to supply said coolant reducing agent, for which purpose the feed
device is adapted to being run at reduced power compared with
ordinary operation.
[0044] The feed device may be adapted to being run at reduced power
compared with ordinary operation.
[0045] The feed device may be adapted to being run intermittently
with a predetermined interval configuration.
[0046] Said predetermined interval configuration may entail
catering for rewarming effects of said dosing unit.
[0047] The feed device may be adapted to being activated on the
basis of a measured temperature of at least one portion of said SCR
system.
[0048] The feed device may be adapted to effecting, during
operation, cooling of said dosing unit to a temperature which is
below a predetermined limit value.
[0049] Said reducing agent may be a fluid solution which contains
urea.
[0050] The above objects are also achieved with a motor vehicle
which comprises an SCR system. The vehicle may be a truck, bus or
passenger car.
[0051] An aspect of the invention proposes any platform which
comprises an SCR system, e.g. a watercraft. The watercraft may be
of any kind, e.g. a motorboat, a steamer, a ferry or a ship.
[0052] An aspect of the invention proposes a computer programme
pertaining to SCR systems for exhaust cleaning which contains
programme code for causing an electronic control unit or another
computer connected to the electronic control unit to perform steps
according to any of claims 1-6.
[0053] An aspect of the invention proposes a computer programme
pertaining to SCR systems for exhaust cleaning which contains
programme code stored on a computer-readable medium for causing an
electronic control unit or another computer connected to the
electronic control unit to perform steps according to any of claims
1-6.
[0054] An aspect of the invention proposes a computer programme
product containing a programme code stored on a computer-readable
medium for performing method steps according to any of claims 1-6
when said programme is run on an electronic control unit or another
computer connected to the electronic control unit.
[0055] Further objects, advantages and novel features of the
present invention will become apparent to one skilled in the art
from the following details, and also by putting the invention into
practice. Whereas the invention is described below, it should be
noted that it is not restricted to the specific details described.
Specialists having access to the teachings herein will recognise
further applications, modifications and incorporations within other
fields, which are within the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0056] For fuller understanding of the present invention and
further objects and advantages of it, the detailed description set
out below should be read together with the accompanying drawings,
in which the same reference notations denote similar items in the
various diagrams, and in which:
[0057] FIG. 1 illustrates schematically a vehicle according to an
embodiment of the invention;
[0058] FIG. 2 illustrates schematically a subsystem for the vehicle
depicted in FIG. 1, according to an embodiment of the
invention;
[0059] FIG. 3a is a schematic diagram of operating power of a feed
device as a function of time, according to an embodiment of the
invention;
[0060] FIG. 3b is a schematic diagram of operating power of a feed
device as a function of time, according to an embodiment of the
invention;
[0061] FIG. 4a is a schematic flowchart of a method according to an
embodiment of the invention;
[0062] FIG. 4b is a more detailed schematic flowchart of a method
according to an embodiment of the invention; and
[0063] FIG. 5 illustrates schematically a computer according to an
embodiment of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0064] FIG. 1 depicts a side view of a vehicle 100. The exemplified
vehicle 100 comprises a tractor unit 110 and a trailer 112. The
vehicle may be a heavy vehicle, e.g. a truck or a bus. The vehicle
may alternatively be a passenger car.
[0065] It should be noted that the invention is applicable to any
SCR system and is therefore not restricted to SCR systems of motor
vehicles. The innovative method and the innovative SCR system
according to an aspect of the invention are well suited to other
platforms which have an SCR system than motor vehicles, e.g.
watercraft. The watercraft may be of any kind, e.g. motorboats,
steamers, ferries or ships.
[0066] The innovative method and the innovative SCR system
according to an aspect of the invention are also well suited to for
example, systems which comprise industrial engines and/or
engine-powered industrial robots.
[0067] The innovative method and the innovative SCR system
according to an aspect of the invention are also well suited to
various kinds of power plants, e.g. an electric power plant
comprising a diesel generator.
[0068] The innovative method and the innovative SCR system are well
suited to any engine system which comprises an engine and an SCR
system, e.g. on a locomotive or some other platform.
[0069] The innovative method and the innovative SCR system are well
suited to any system which comprises an NO generator and an SCR
system.
[0070] The term "link" refers herein to a communication link which
may be a physical connection such as an opto-electronic
communication line, or a non-physical connection such as a wireless
connection, e.g. a radio link or microwave link.
[0071] The term "line" refers herein to a passage for holding and
conveying a fluid, e.g. a reducing agent in liquid form. The line
may be a pipe of any suitable size. The line may be made of any
suitable material, e.g. plastic, rubber or metal.
[0072] The term "reductant" or "reducing agent" refers herein to an
agent used for reacting with certain emissions in an SCR system.
These emissions may for example be NOx gas. The terms "reductant"
and "reducing agent" are herein used synonymously. Said reductant
according to a version is so-called AdBlue. Other kinds of
reductants may of course be used. AdBlue is herein cited as an
example of a reductant, but specialists will appreciate that the
innovative method and the innovative device are feasible with other
types of reductants, subject to necessary adaptations, e.g.
adaptations to adequate freezing points for chosen reductants, in
control algorithms for executing software code in accordance with
the innovative method.
[0073] FIG. 2 depicts a subsystem 299 of the vehicle 100. The
subsystem 299 is situated in the tractor unit 110. The subsystem
299 may be part of an SCR system. The subsystem 299 comprises in
this example a container 205 arranged to hold a reductant. The
container 205 is adapted to containing a suitable amount of
reductant and to being replenishable as necessary. The container
might accommodate, for example, 75 or 50 litres of reductant.
[0074] A first line 271 is adapted to leading the reductant to a
pump 230 from the container 205. The pump 230 may be any suitable
pump. The pump 230 may be a diaphragm pump provided with at least
one filter. The pump 230 is adapted to being driven by an electric
motor. The pump 230 is adapted to drawing the reductant from the
container 205 via the first line 271 and supplying it via a second
line 272 to a dosing unit 250. The dosing unit 250 comprises an
electrically controlled dosing valve by means of which a flow of
reductant added to the exhaust system can be controlled. The pump
230 is adapted to pressurising the reductant in the second line
272. The dosing unit 250 is provided with a throttle unit against
which said pressure of the reductant is built up in the subsystem
299.
[0075] The dosing unit 250 is adapted to supplying said reductant
to an exhaust system (not depicted) of the vehicle 100. More
specifically, the dosing unit 250 is adapted to supplying a
suitable amount of reductant in a controlled way to an exhaust
system of the vehicle 100. According to this version, an SCR
catalyst (not depicted) is situated downstream of a location in the
exhaust system where the reductant supply is effected. The amount
of reductant supplied in the exhaust system is intended to be used
in a conventional way in the SCR catalyst for reducing the amount
of undesirable emissions in a known way.
[0076] The dosing unit 250 is situated adjacent to, for example, an
exhaust pipe which is adapted to leading exhaust gases from a
combustion engine (not depicted) of the vehicle 100 to the SCR
catalyst. The dosing unit 250 is situated in thermal contact with
the exhaust system of the vehicle 100. This means that thermal
energy stored in, for example, an exhaust pipe, silencer and SCR
catalyst can thus be led to the dosing unit.
[0077] The dosing unit 250 is provided with an electronic control
card which is adapted to handling communication with a control unit
200. The dosing unit 250 comprises also plastic and/or rubber
components which might melt or be otherwise adversely affected as a
result of too high temperatures.
[0078] The dosing unit 250 is sensitive to temperatures above a
certain value, e.g. 120 degrees Celsius. As for example the exhaust
pipe, the silencer and the SCR catalyst of the vehicle 100 exceed
this temperature value, there is risk that the dosing unit might
become overheated during or after operation of the vehicle if not
provided with cooling.
[0079] A third line 273 runs between the dosing unit 250 and the
container 205. The third line 273 is adapted to leading back to the
container 205 a certain amount of the reductant fed to the dosing
valve 250. This configuration achieves with advantage cooling of
the dosing unit 250. The dosing unit 250 is thus cooled by a flow
of the reductant as it is pumped through the dosing unit 250 from
the pump 230 to the container 205.
[0080] A first radiator liquid line 281 is adapted to holding and
conveying coolant for an engine of the vehicle 100. The first
radiator liquid line 281 is partly situated in the container 205 in
order to warm the reductant present therein if the reductant is
cold. In this example, the first radiator liquid line 281 is
adapted to leading radiator liquid which has been warmed by the
vehicle's engine in a closed circuit through the container 205 to
the pump 230. A second radiator liquid line 282 is adapted to
leading radiator liquid back from the pump 230 to the engine of the
vehicle 100. According to a version, the first radiator liquid line
281 is configured with a substantially U-shaped portion situated in
the container 205, as schematically depicted in FIG. 2. This
configuration achieves improved warming of the reductant in the
container 205 when the reductant is at too low a temperature to
function in a desirable way. It should be noted that the first
radiator liquid line 281 may be of any suitable configuration. If
the reductant is at a temperature which exceeds a predetermined
value, warming of the reductant by the radiator liquid is
deactivated automatically.
[0081] A first control unit 200 is arranged for communication with
a temperature sensor 220 via a link 293. The temperature sensor 220
is adapted to detecting a prevailing temperature of the reductant
where the sensor is fitted. According to this version, the
temperature sensor 220 is situated at a bottom of the substantially
U-shaped configuration of the first radiator liquid line 281. The
temperature sensor 220 is adapted to continuously sending signals
to the first control unit 200 which contain information about a
prevailing temperature of the reductant.
[0082] According to an alternative, the temperature sensor 220 is
situated adjacent to the dosing unit 250 in order to detect a
prevailing temperature there. According to another version, the
temperature sensor 220 is situated adjacent to the SCR catalyst of
the SCR system in order to detect a prevailing temperature there.
Any desired number of temperature sensors may be provided in the
subsystem 299 to detect a prevailing temperature adjacent thereto.
The temperature sensor/sensors 220 is/are adapted to detecting at a
suitable location within the subsystem 299 a prevailing temperature
which may serve as a basis for controlling operation of the pump
230 in order to cool the dosing unit by means of said flow of
reductant.
[0083] The first control unit 200 is arranged for communication
with the pump 230 via a link 292. The first control unit 200 is
adapted to controlling operation of the pump 230 in order for
example to regulate the reductant flows within the subsystem
299.
[0084] The first control unit 200 is arranged for communication
with the dosing unit 250 via a link 291. The first control unit 200
is adapted to controlling operation of the dosing unit 250 in order
for example to regulate the reductant supply to the exhaust system
of the vehicle 100. The first control unit 200 is adapted to
controlling operation of the dosing unit 250 in order for example
to regulate the reductant return supply to the container 205.
[0085] The first control unit 200 is adapted, according to a
version, to using the signals received which contain a prevailing
temperature of the reductant in the region of the temperature
sensor 220 and/or a prevailing temperature of any desired component
of the SCR system or the subsystem 299 as a basis for controlling
the pump 230 in accordance with an aspect of the innovative method.
In particular, the first control unit 200 is adapted, according to
a version, to using the signals received which contain a prevailing
temperature of the reductant in the region of the temperature
sensor 220 and/or a prevailing temperature of any desired component
of the SCR system or the subsystem 299 as a basis for controlling
operation of the pump 230 at reduced power compared with ordinary
operation after cessation of an exhaust flow from the engine, in
accordance with an aspect of the innovative method.
[0086] A second control unit 210 is arranged for communication with
the first control unit 200 via a link 290. The second control unit
210 may be detachably connected to the first control unit 200. The
second control unit 210 may be a control unit external to the
vehicle 100. The second control unit 210 may be adapted to
performing the innovative method steps according to the invention.
The second control unit 210 may be used to cross-load software to
the first control unit 200, particularly software for applying the
innovative method. The second control unit 210 may alternatively be
arranged for communication with the first control unit 200 via an
internal network in the vehicle. The second control unit 210 may be
adapted to performing substantially similar functions to those of
the first control unit 200, e.g. using the signals received which
contain a prevailing temperature of the reductant in the region of
the temperature sensor 220 and/or a prevailing temperature of any
desired component of the SCR system or the subsystem 299 as a basis
for controlling operation of the pump 230 at reduced power compared
with ordinary operation after cessation of an exhaust flow from the
engine. It should be noted that the innovative method may be
applied by either the first control unit 200 or the second control
210 or by both the first control unit 200 and the second control
unit 210.
[0087] According to the embodiment schematically illustrated in
FIG. 2, the first control unit 200 is adapted to controlling
operation of the pump 230 at reduced power compared with ordinary
operation after cessation of an exhaust flow from the engine in
such a way that any amount of electrical energy which may be needed
for cooling the dosing unit 250 to a critical temperature as
regards safety is less than in the state of the art.
[0088] FIG. 3a is a schematic diagram of an operating power P of
the feed device as a function of time t, according to an embodiment
of the invention.
[0089] The diagram illustrates schematically how the feed device
230 may be run on the basis of a first predetermined interval
configuration. According to the first interval configuration, the
feed device 230 continues, where a need for cooling of the dosing
unit 250 is found after cessation of the exhaust flow, to be run at
an ordinary operating power P1 until a first time t1. Between the
first time t1 and a second time the operating power P of the feed
device 230 is zero (0) and the feed device is therefore off or
idling. After the second time t2 the feed device 230 is run at an
ordinary operating power P1 until a third time t3. After the third
time t3, the operating power P of the feed device 230 is zero (0)
and the feed device is therefore off or idling. At a fourth time it
is found that predetermined criteria are fulfilled and the feed
device therefore continues to be off. At the fourth time t4 it is
found that it will not be possible for a prevailing temperature of
the dosing unit 250 to be increased by rewarming effects to too
high a temperature at which there would be risk of its functional
degradation.
[0090] According to the first predetermined interval configuration,
the period t1-t2 and the period t2-t3 are of substantially equal
duration.
[0091] It should be noted that various periods of operation and
non-operation of the feed device in a predetermined interval
configuration may differ in length according to a version. It
should also be noted that an interval configuration may also have
any desired number of periods of operation and non-operation of the
feed device. According to a version, the periods relating to
operation of the feed device (e.g. the period t2-t3) are within a
range of 30 to 90 seconds. According to a version, the periods
relating to operation of the feed device (e.g. the period t2-t3)
are within a range of 1 to 5 minutes. According to a version, the
periods relating to operation of the feed device (e.g. the period
t2-t3) are shorter than one (1) minute. According to a version, the
periods relating to operation of the feed device (e.g. the period
t2-t3) are longer than five (5) minutes.
[0092] According to a version, the predetermined interval
configuration has a length of the order of 30 minutes. The
predetermined interval configuration may be shorter than 30
minutes. The predetermined interval configuration may be longer
than 30 minutes.
[0093] A version of the invention determines at any desired times
in an interval configuration whether a predetermined criterion is
fulfilled, in which case switching off of the feed device 230 may
be effected on that basis. Said predetermined criterion is
described in more detail with reference to FIG. 4b below.
[0094] FIG. 3b is a schematic diagram of operating power of the
feed device as a function of time, according to an embodiment of
the invention.
[0095] It illustrates schematically how the feed device 230 may be
run on the basis of a second predetermined interval configuration.
According to the second interval configuration, the feed device 230
continues, where a need for cooling of the dosing unit 250 is
determined after cessation of the exhaust flow, to be run at a
reduced operating power P2, compared with ordinary operation, until
a first time t1. Between the first time t1 and a second time the
operating power P of the feed device 230 is zero (0) and the feed
device is therefore off or idling. After the second time t2 the
feed device 230 is run at operating power P2 until a third time
t3'. The period t2-t3' is shorter than the period t2-t3 described
with reference to FIG. 3a. After the third time t3', the operating
power P of the feed device 230 is zero (0) until a fourth time t4'
and the feed device is therefore off or idling. The period t3'-t4'
is shorter than the period t3-t4 described with reference to FIG.
3a. After the fourth time t4' the feed device 230 is run at further
reduced operating power until a fifth time t5. At the fifth time t5
it is found that predetermined criteria are fulfilled and the feed
device then continues to be off, whereupon the operating power
becomes zero (0). At the fifth time t5 it is found that it will not
be possible for a prevailing temperature of the dosing unit 250 to
be increased by rewarming effects to too high a temperature at
which there would be risk of its functional degradation.
[0096] FIG. 4a is a schematic flowchart of a method for cooling a
dosing unit pertaining to SCR systems for exhaust cleaning,
according to an embodiment of the invention. The method comprises a
first step s401. Method step s401 comprises, after cessation of
exhaust flow, the steps of cooling a reducing agent dosing unit by
means of reducing agent supplied to it, and of intermittently
running a feed device to supply said coolant reducing agent, and
running said feed device at reduced power compared with ordinary
operation. The method ends after step s401.
[0097] FIG. 4b is a schematic flowchart of a method pertaining to
SCR systems for exhaust cleaning, according to an embodiment of the
invention.
[0098] The method comprises a first step s410. Method step s410
comprises the step of shutting off an exhaust flow from a
combustion engine of the vehicle 100. At this stage, the dosing
unit 250 is cooled in an ordinary way, i.e. at an operating power
of the pump 230 which is needed to maintain the same cooling flow
of the dosing unit as during ordinary operation. Shutting off the
exhaust flow is effected by switching off the engine of the vehicle
100. Step s410 is followed by a step s420.
[0099] Method step s420 comprises the step of evaluating whether
there is a continuing need to cool the dosing unit by means of a
flow of the reductant in the SCR system. The step of deciding
whether there is a need to continue said cooling may be based on
various parameters. According to an example, deciding whether there
is a continuing need for cooling is based on the signals from the
temperature sensor 220 which contain information about a prevailing
temperature of at least one component of the SCR system or the
subsystem 299 of the vehicle 100. If there is no continuing need
for cooling, the method ends. If there is a continuing need for
cooling, a subsequent step s430 is performed.
[0100] Method step s430 comprises the step of influencing the
operation of the pump 230 in such a way that it is run
intermittently. According to a version, the pump 230 is run
intermittently with a predetermined interval configuration.
According to a version, the pump 230 is run intermittently at an
operating power corresponding to that of ordinary operation.
According to a version, the pump 230 is run intermittently at a
reduced operating power compared with that employed for maintaining
a cooling flow of the dosing unit 250 during ordinary operation.
Step s430 is followed by a step s440.
[0101] Method step s440 comprises the step of deciding whether a
predetermined criterion is fulfilled. The predetermined criterion
may be any desired criterion. Said criterion may be related to a
predetermined interval configuration. Said criterion may be related
to a measured temperature of at least one portion of said SCR
system. Said criterion may be related to rewarming effects of at
least one portion of said SCR system. The predetermined criterion
may thus be fulfilled if the operating power of the pump 230 has
been controlled in accordance with the predetermined interval
configuration, in which case it may be assumed that the dosing unit
250 has reached a desired temperature at which it needs no further
cooling. If a predetermined temperature of at least one portion of
the SCR system is reached, after the pump 230 has been run
intermittently in a certain way, it may be assumed that the dosing
unit 250 has reached a desired temperature at which it needs no
further cooling. If it is decided at step s440 that the
predetermined criterion is fulfilled, the method ends. If it is
decided at step s440 that the predetermined criterion is not
fulfilled, the pump 230 continues to be run intermittently,
possibly also at reduced power compared with ordinary operation,
and step s440 is performed again. The method ends after step
s440.
[0102] FIG. 5 is a diagram of a version of a device 500. The
control units 200 and 210 described with reference to FIG. 2 may in
a version comprise the device 500. The device 500 comprises a
non-volatile memory 520, a data processing unit 510 and a
read/write memory 550. The non-volatile memory 520 has a first
memory element 530 in which a computer programme, e.g. an operating
system, is stored for controlling the function of the device 500.
The device 500 further comprises a bus controller, a serial
communication port, I/O means, an ND converter, a time and date
input and transfer unit, an event counter and an interruption
controller (not depicted). The non-volatile memory 520 has also a
second memory element 540.
[0103] A proposed computer programme P comprises routines for,
after cessation of exhaust flow, cooling the reducing agent dosing
unit by means of reducing agent supplied to it, and for
intermittently running a feed device to supply said coolant
reducing agent, and for running said feed device at reduced power
compared with ordinary operation, according to the innovative
method. The programme P may be stored in an executable form or in a
compressed form in a memory 560 and/or in a read/write memory
550.
[0104] Where the data processing unit 510 is described as
performing a certain function, it means that the data processing
unit 510 effects a certain part of the programme stored in the
memory 560, or a certain part of the programme stored in the
read/write memory 550.
[0105] The data processing device 510 can communicate with a data
port 599 via a data bus 515. The non-volatile memory 520 is
intended for communication with the data processing unit 510 via a
data bus 512. The separate memory 560 is intended to communicate
with the data processing unit 510 via a data bus 511. The
read/write memory 550 is adapted to communicating with the data
processing unit 510 via a data bus 514. The data port 599 may for
example have the links 290, 291, 292 and 293 connected to it (see
FIG. 2).
[0106] When data are received on the data port 599, they are stored
temporarily in the second memory element 540. When input data
received have been temporarily stored, the data processing unit 510
is prepared to effect code execution as described above. According
to a version, signals received on the data port 599 contain
information about a prevailing temperature of at least one portion
of the SCR system. The signals received on the data port 599 may be
used by the device 500 to run the pump 230 intermittently according
to an aspect of the invention. The signals received on the data
port 599 may used by the device 500 to run the pump 230
intermittently with a predetermined interval configuration,
according to an aspect of the invention. The signals received on
the data port 599 may be used by the device 500 to run the pump 230
intermittently at reduced operating power compared with ordinary
operation and, where applicable, with a predetermined interval
configuration, according to an aspect of the invention.
[0107] Parts of the methods herein described may be effected by the
device 500 by means of the data processing unit 510 which runs the
programme stored in the memory 560 or the read/write memory 550.
When the device 500 runs the programme, methods herein described
are executed.
[0108] The foregoing description of the preferred embodiments of
the present invention is provided for illustrative and descriptive
purposes. It is not intended to be exhaustive or to restrict the
invention to the variants described. Many modifications and
variations will obviously be apparent to one skilled in the art.
The embodiments have been chosen and described in order best to
explain the principles of the invention and its practical
applications and hence make it possible for specialists to
understand the invention for various embodiments and with the
various modifications appropriate to the intended use.
* * * * *