U.S. patent application number 11/568256 was filed with the patent office on 2007-11-01 for liquid supply device for exhaust gas post-treatment device.
This patent application is currently assigned to BOSCH CORPORATION. Invention is credited to Junichi Kaneko.
Application Number | 20070251226 11/568256 |
Document ID | / |
Family ID | 35241737 |
Filed Date | 2007-11-01 |
United States Patent
Application |
20070251226 |
Kind Code |
A1 |
Kaneko; Junichi |
November 1, 2007 |
Liquid Supply Device for Exhaust Gas Post-Treatment Device
Abstract
In a thermal-maintaining device (40) which is mounted to
thermally maintain a pipe (3) for supplying urea water solution U
stored in the inside of a tank (2) to an exhaust gas post-treatment
device (100), a selecting part (50) which selectively outputs an
ambient temperature signal (S2) when it is determined that the urea
water solution (U) in the inside of the pipe (3) is frozen based on
a flow state of the urea water solution (U) in the inside of the
pipe (3), and selectively outputs a tank temperature signal (S1)
when it is determined that the urea water solution (U) in the
inside of the pipe (3) flows is provided. Further, a drive current
(Y) necessary for thermal-maintenance is supplied to a heater (17A)
in response to an output signal (S3) from the selecting part
(50).
Inventors: |
Kaneko; Junichi; (Saitama,
JP) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
1875 EYE STREET, N.W.
SUITE 1100
WASHINGTON
DC
20036
US
|
Assignee: |
BOSCH CORPORATION
6-7, Shibuya 3-chome Shibuya-ku
Tokyo
JP
150-8360
|
Family ID: |
35241737 |
Appl. No.: |
11/568256 |
Filed: |
April 14, 2005 |
PCT Filed: |
April 14, 2005 |
PCT NO: |
PCT/JP05/07567 |
371 Date: |
July 12, 2007 |
Current U.S.
Class: |
60/317 |
Current CPC
Class: |
Y02T 10/24 20130101;
F01N 11/00 20130101; F01N 2550/05 20130101; Y02T 10/40 20130101;
F01N 2900/1811 20130101; Y02T 10/47 20130101; F01N 2610/14
20130101; F01N 3/208 20130101; F01N 2900/12 20130101; Y02T 10/12
20130101; F01N 2610/02 20130101; F01N 2610/08 20130101; F01N
2610/10 20130101 |
Class at
Publication: |
060/317 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2004 |
JP |
2004-135450 |
Claims
1. A liquid supply device for an exhaust gas post-treatment device
which supplies liquid stored in the inside of a tank to an exhaust
gas purifying device through a pipe, and the pipe being thermally
maintained using a thermally-maintaining device after thawing the
liquid in the inside of the tank, wherein the thermally-maintaining
device includes: a tank temperature sensor which detects a
temperature in the inside of the tank; an ambient temperature
sensor which detects an ambient temperature; a heater which heats
the pipe; a selecting part which selects either one of an output of
the ambient temperature sensor and an output of the tank
temperature sensor based on a flow state of the liquid in the
inside of the pipe; and a driving part which supplies a current for
thermal-maintenance necessary for thermal-maintenance in response
to the output from the selecting part.
2. A liquid supply device for an exhaust gas post-treatment device
according to claim 1, wherein the selecting part includes a
detecting part which detects a flow state of liquid in the inside
of the pipe, and a switching part which selects either one of the
output of the ambient temperature sensor and the output of the tank
temperature sensor in response to the detecting part.
3. A liquid supply device for an exhaust gas post-treatment device
according to claim 1, wherein the selecting part selectively
outputs the output of the ambient temperature sensor when it is
determined that the liquid is frozen in the inside of the pipe
based on the flow state of the liquid in the inside of the pipe,
and selectively outputs the output of the tank temperature sensor
when it is determined that the liquid flows in the inside of the
pipe.
4. A liquid supply device for an exhaust gas post-treatment device
according to claim 1, wherein the driving part outputs a pulse
current of a duty ratio which is controlled in response to the
output from the selecting part.
5. A liquid supply device for an exhaust gas post-treatment device
according to claim 4, wherein the driving part sets the duty ratio
of the pulse current to a predetermined fixed value when thawing
the liquid in the inside of the tank.
6. A liquid supply device for an exhaust gas post-treatment device
according to claim 4, wherein the driving part further includes a
determining part which determines whether the liquid in the inside
of the pipe is required to be thawed or thermally maintained or
not, and outputs the pulse current only when it is determined that
the liquid in the inside of the pipe is required to be thawed or
thermally maintained.
7. A liquid supply device for an exhaust gas post-treatment device
according to claim 5, wherein the driving part further includes a
determining part which determines whether the liquid in the inside
of the pipe is required to be thawed or thermally maintained or
not, and outputs the pulse current only when determined that the
liquid in the inside of the pipe is required to be thawed or
thermally maintained.
8. A liquid supply device for an exhaust gas post-treatment device
according to claim 6, wherein the determining part responds to the
tank temperature sensor or the ambient temperature sensor and
performs the determination based on whether either one of the tank
temperature and an ambient temperature becomes a urea-water
freezing temperature or below.
9. A liquid supply device for an exhaust gas post-treatment device
according to claim 7, wherein the determining part responds to the
tank temperature sensor or the ambient temperature sensor and
performs the determination based on whether either one of a tank
temperature and an ambient temperature becomes a urea-water
freezing temperature or below.
10. A liquid supply device for an exhaust gas post-treatment device
according to claim 2, wherein the selecting part selectively
outputs the output of the ambient temperature sensor when it is
determined that the liquid is frozen in the inside of the pipe
based on the flow state of the liquid in the inside of the pipe,
and selectively outputs the output of the tank temperature sensor
when it is determined that the liquid flows in the inside of the
pipe.
11. A liquid supply device for an exhaust gas post-treatment device
according to claim 2, wherein the driving part outputs a pulse
current of a duty ratio which is controlled in response to the
output from the selecting part.
Description
TECHNICAL FIELD
[0001] The present invention relates to a liquid supply device for
an exhaust gas post-treatment device.
BACKGROUND ART
[0002] To purify exhaust gas of a diesel engine, an exhaust gas
post-treatment system which sprays an urea water solution into an
exhaust gas through a nozzle and purifies the exhaust gas by using
a catalytic conversion action is known (JP-3022601) This technique
is basically based on a selective catalytic reduction process, and
the urea water solution is used in place of ammonia as a reducing
agent for catalytic conversion of nitrogen oxide.
[0003] Although this type of liquid used for the exhaust gas
treatment is stored in a tank or the like, since an outside air
temperature in a cold district reaches a freezing point or below,
there exists a fear that the liquid in the inside of the tank is
frozen so that it is impossible to supply the liquid. For this end,
the constitution which can prevent the liquid in the inside of the
storing tank from being frozen by providing a heating device to the
storing tank or the like has been adopted.
[0004] This type of a liquid supply device is configured such that
the liquid in the inside of the storing tank is fed to a pump
module through a liquid supply pipe, the liquid is pressurized in
the pump module, and is sprayed into an exhaust pipe. Since a
temperature of the liquid supply pipe also becomes the outside air
temperature outside a vehicle, there exists a fear that the liquid
is also frozen in the inside of the liquid supply pipe. However,
since the liquid supply pipe is mounted on a vehicle in an assembly
line of a vehicle body in conformity with a type of the vehicle
based on the different specification, a thermal sensor is not
mounted on the pipe. Accordingly, conventionally, a heating control
of the liquid supply pipe is performed using information from a
temperature sensor for detecting the temperature of the liquid in
the inside of the storage tank thus performing a heat insulation
control to prevent the liquid from being frozen in the inside of
the pipe.
[0005] However, heat capacity of the liquid supply pipe is small
compared with heat capacity of the storage tank and hence, the
liquid is liable to be easily frozen in the inside of the pipe
whereby the conventional constitution cannot guarantee a thawing
state of the liquid in the inside of the liquid supply pipe.
Accordingly, there has been adopted the constitution which operates
a pressurizing pump when a temperature of the liquid in the inside
of the storage tank becomes a predetermined value or more,
determines that thawing is completed when the elevation of pressure
is confirmed on an output side of the pressurizing pump and,
thereafter, enters a heat insulation mode.
[0006] With respect to the operation of a heater for heating the
liquid supply pipe after the completion of thawing is performed, an
operation to set the heater in an OFF mode when the temperature in
the inside of the storage tank exceeds a threshold value and an
operation to set the heater in a heat insulation mode when the
temperature in the inside of the storage tank becomes lower than
the threshold value are repeated. The heater is driven with a pulse
current in the respective modes and a method for calculating a
drive duty ratio has the following two options and these modes can
be selected by data setting.
[0007] 1. The drive duty ratio is obtained based on a value of an
ambient temperature.
[0008] 2. The drive duty ratio is obtained based on the temperature
of the liquid in the storage tank and temperature of the liquid in
the pressuring pump.
[0009] However, these conventional options have the following
drawbacks respectively.
[0010] First of all, in obtaining the drive duty ratio based on the
value of the ambient temperature, even when the temperature of the
liquid inside the liquid supply pipe is elevated due to the
circulation of the liquid in the inside of the heated storage tank,
the drive duty ratio is fixed and hence, there exists a fear of
overheating. Secondly, in obtaining the drive duty ratio based on
the temperature of the liquid in the storage tank and temperature
of the liquid in the pressuring pump, when there is no circulation
of the liquid in the inside of the liquid supply pipe, since the
pipe has the small heat capacity compared to the storage tank, the
lowering of the temperature of the liquid supply pipe is
accelerated. Accordingly, the liquid in the inside of the liquid
supply pipe is cooled by the ambient temperature and the
temperature is lowered than the calculated temperature. In spited
of such a circumstance, there exists a fear that the heater is
operated with the low duty ratio leading to the insufficient
heating.
[0011] Accordingly, it is an object of the present invention to
provide a liquid supply device for an exhaust gas post-treatment
device which can overcome the above-mentioned drawbacks.
DISCLOSURE OF THE INVENTION
[0012] To overcome the above mentioned drawbacks, the present
invention provides a liquid supply device for an exhaust gas
post-treatment device which supplies liquid stored in the inside of
a tank to an exhaust gas purifying device through a pipe, and
thermally maintains the liquid using a thermally-maintaining device
after thawing the liquid in the inside of the tank, wherein the
thermally-maintaining device includes a tank temperature sensor
which detects a temperature in the inside of the tank, an ambient
temperature sensor which detects an ambient temperature, a heater
which heats the pipe, a selecting part which selects either one of
an output of the ambient temperature sensor and an output of the
tank temperature sensor based on a flow state of the liquid in the
inside of the pipe and a driving part which supplies a current for
thermal-maintenance necessary for thermal-maintenance to the heater
in response to the output from the selecting part.
[0013] According to the present invention, after thawing the liquid
in the inside of the tank, a current which flows in the heater is
controlled based on the output of the desired sensor out of the
tank temperature sensor and the ambient temperature sensor, and
whether the liquid flows in the inside of the pipe and hence, the
thermal-maintenance of the pipe can be appropriately performed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a constitutional view showing one example of a
liquid supply device for an exhaust gas post-treatment device
according to the present invention.
[0015] FIG. 2 is a detailed constitutional view of a
thermal-maintaining device shown in FIG. 1.
BEST MODE FOR CARRYING OUT THE INVENTION
[0016] To explain the present invention in more detail, the present
invention is explained in conjunction with attached drawings.
[0017] FIG. 1 is a constitutional view showing one example of a
liquid supply device for an exhaust gas post-treatment device
according to the present invention. A liquid supply device 1 is a
device for supplying urea water solution in the exhaust gas
post-treatment, and includes a tank 2 for storing the urea water
solution U and a pipe 3 for introducing the urea water solution U
in the tank 2 into an exhaust gas post-treatment device 100. In
this embodiment, the exhaust gas post-treatment device 100 is
mounted on an exhaust pipe 101, and the urea water solution U is
injected into and is supplied to the inside of the exhaust pipe 101
through an injection nozzle 4 which is mounted on a distal end
portion of the pipe 3 at an upstream side of the exhaust gas
post-treatment device 100.
[0018] On a middle portion of the pipe 3, a pump 5 for pressurizing
the urea water solution U and a dosing valve 6 are mounted. The
dosing valve 6 is connected to an air reservoir 7 by way of a pipe
8, and by performing an open/close control of a shut-off valve 9
which is mounted on the pipe 8, the supply of compressed air to the
dosing valve 6 can be controlled. Numeral 10 indicates a relief
valve. Further, between the tank 2 and the dosing valve 6, a return
pipe 12 having a relief valve 11 is provided. An extra amount of
the urea water solution U which is fed to the dosing valve 6 by way
of the pipe 3 is returned to the tank 2 by way of the relief valve
11. Here, a pressure sensor 20 for measuring pressure is mounted on
the pipe in the vicinity of the pump 5 and is used to confirm the
injection pressure or the like. Further, the dosing valve 6 and the
shut-off valve 9 are configured to perform predetermined operations
in response to control signals C1, C2 from respective control units
not shown in drawings.
[0019] To thaw the urea water solution U in the tank 2 when the
urea water solution U is frozen and, at the same time, to thermally
maintain the tank 2 for preventing the urea water solution U from
being frozen, a thawing and thermal-maintaining device 30 is
provided. The thawing and thermal-maintaining device 30 includes a
cooling water pipe 13 for circulating cooling water for an engine
not shown in drawings in the inside of the tank 2, a shut-off valve
14 which is mounted on the cooling water pipe 13, and a first
control unit 15 for performing an ON-OFF control of the shut-off
valve 14 to control the circulation of the cooling water in the
inside of the cooling water pipe 13. To the first control unit 15,
a tank temperature signal S1 is inputted from a tank temperature
sensor 16 for detecting a temperature of the urea water solution U
in the inside of the tank 2.
[0020] The first control unit 15 determines whether the urea water
solution U in the inside of the tank 2 is frozen or not in response
to the tank temperature signal S1, and a thawing and
thermal-maintaining control signal M1 which is outputted for
thawing and thermal-maintaining from the first control unit 15 in
accordance with a result of the determination is inputted into the
shut-off valve 14. Accordingly, the ON-OFF control of the shut-off
valve 14 is performed in response to the thawing and
thermal-maintaining control signal M1 and hence, the supply of the
cooling water to the cooling water pipe 13 is adjusted thus
performing the thawing and thermal-maintenance of the urea water
solution U in the inside of the tank 2.
[0021] The liquid supply device 1 further includes a
thermal-maintaining device 40 which performs a thermal-maintaining
operation for preventing the urea water solution U in the inside of
the pipe 3 from being frozen again after the urea water solution U
in the inside of the tank 2 thaws and flows in the inside of the
pipe 3.
[0022] The thermal-maintaining device 40 includes a heater 17A for
heating the pipe 3 and a heater 17B for heating a return pipe 12.
Here, the heaters 17A, 17B are constituted as electric heaters. The
thermal-maintaining device 40 includes a second control unit 19 to
which the tank temperature signal S1 from the tank temperature
sensor 16, an ambient temperature signal S2 which is outputted from
an ambient temperature sensor 18 for detecting the ambient
temperature of the liquid supply device 1 and indicates an ambient
temperature and a thawing and thermal-maintaining control signal M1
are inputted. A drive current Y necessary for performing desired
heating is supplied from the second control unit 19 to the heaters
17A, 17B.
[0023] FIG. 2 is a detailed constitutional view of the
thermal-maintaining device 40. The thermal-maintaining device 40
includes a selecting part 50 to which the tank temperature signal
S1 and the ambient temperature signal S2 are inputted and which
selects and output either one of the above-mentioned signals in
response to a target-injection-quantity signal for controlling a
quantity of the urea water solution U in the inside of the pipe 3,
and a drive part 60 which supplies the drive current Y necessary
for thermally maintaining the pipe 3 to the heaters 17A, 17B in
response to an output signal S3 from the selecting part 50. The
drive current Y adopts a pulse current mode in which a duty ratio
of the current is determined in a manner described later. Here, the
second control unit 19 shown in FIG. 1 is constituted of the
selecting part 50 and the drive part 60.
[0024] The selecting part 50 includes a detecting part 51 for
detecting whether the urea water solution U flows in the inside of
the pipe 3 or not in response to the target-injection-quantity
signal and a lapsed time, and a first switch part 52 for selecting
either one of the tank temperature signal S1 or the ambient
temperature signal S2 in response to a detection output signal SK
from the detecting part 51 and outputs the selected signal as the
output signal S3. The detecting part 51 is provided for detecting a
flow state of the urea water solution U in the inside of the pipe
3. In the detecting part 51, when a detection result that the urea
water solution U does not flow in the inside of the pipe 3 is
obtained, the ambient temperature signal S2 is selected. In the
detecting part 51, when a detection result that the urea water
solution U flows in the inside of the pipe 3 is obtained, the tank
temperature signal S1 is selected.
[0025] The drive part 60 includes a map arithmetic operation part
61 which responds to the output signal S3 and performs a map
arithmetic operation of a duty ratio of the drive current Y in
accordance with a temperature indicated by the output signal S3.
The duty ratio data D1 indicative of the arithmetic operation
result is outputted from the map arithmetic operation part 61, and
the duty ratio data D1 is inputted to a second switch part 62.
Numeral 63 indicates a data outputting part which outputs a fixed
data D2 indicative of a duty ratio 1, and the fixed data D2 is also
inputted to the second switch part 62.
[0026] The thawing and thermal-maintaining control signal M1 is
inputted to the second switch part 62 from the first control unit
15 as a switching control signal. When the thawing and
thermal-maintaining control signal M1 is inputted, that is, when
the first control unit 15 performs a control for turning on the
shut-off valve 14 so as to perform thawing, the fixed data D2 is
selected by the second switch part 62, while in cases other than
the above-mentioned case, the duty ratio data D1 is selected.
[0027] Either data selected in the above-mentioned manner is
supplied to a drive current output part 64 from the second switch
part 62 as output data D3. Numeral 65 indicates a determination
part which determines whether the thawing or the
thermal-maintaining of the urea water solution U in the inside of
the pipe 3 and the return pipe 12 using the heaters 17A, 17B is
necessary or not. The determination part 65 determines whether
either one of the tank temperature signal S1 or the ambient
temperature signal S2 indicates a urea-water freezing temperature
or below or not. The determination data D4 indicative of the
determination result of the determination part 65 is transmitted to
the drive current output part 64. The drive current output part 64
is configured to output the drive current Y of the duty ratio which
conforms to the output data D3 only when the determination part 65
determines that it is necessary to thaw or thermally maintain the
urea water solution U in the inside of the pipe 3 and the return
pipe 12.
[0028] Since the thermal-maintaining device 40 has the
above-mentioned constitution, when the second switch part 62
selects the fixed data D2 in response to the
thawing-and-thermal-maintaining control signal M1, the drive
current Y of the duty ratio 1 is outputted from the drive current
output part 64, and the pipe 3 and the return pipe 12 are heated by
the heaters 17A, 17B for thawing the urea water solution U in the
pipe 3 and the return pipe 12. Here, a thawing state can be
detected by whether a pressure change of the urea water solution is
observed by the pressure sensor 20 or not when the pump 5 is
operated and, at the same time, the relief valve 11 for the extra
amount of the urea water solution U is operated.
[0029] In this manner, when the thawing of the urea water solution
U in the inside of the tank 2 using the thawing and heat insulating
device 30 and the thawing of the urea water solution U in the
inside of the pipe 3 and the return pipe 12 are finished, the
second switch part 62 selects the duty-ratio data D1. Further, only
when the determination part 65 determines that the thawing or the
thermal-maintaining for the pipe 3 is necessary, the drive current
Y of the duty ratio which conforms to the duty-ratio data D1 is
supplied to the heaters 17A, 17B as a current for
thermal-maintaining.
[0030] Since the first switch part 52 selects the tank temperature
signal S1 when the urea water solution U flows in the inside of the
pipe 3, the drive current Y of the duty ratio which conforms to the
temperature of the urea water solution U in the inside of the tank
2 is outputted after the thawing operation. Accordingly, when the
urea water solution U flows in the inside of the pipe 3 after
thawing, the temperature of the urea water solution U in the inside
of the tank 2 and the temperature of the urea water solution U in
the inside of the pipe 3 become substantially equal and hence, the
extremely appropriate thermal-maintaining operation is
guaranteed.
[0031] After thawing, when an exhaust gas becomes a low-NOX state
in an idling or a low load operation and the injection of the urea
water solution is stopped, and time elapses, although the urea
water solution U in the inside of the tank 2 is not frozen, the
urea water solution U in the inside of the low-heat-capacity pipe 3
is frozen. In such a case, the detecting part 51 promptly detects
that the flow of the urea water solution U in the inside of the
pipe 3 is stopped in response to the target-injection-quantity
signal, and hence, the first switch part 52 is changed over to
transmit the ambient temperature signal S2 to the drive part 60 as
the output signal S3. Further, the drive current Y of the duty
ratio which conforms to the detected ambient temperatures is given
to the heaters 17A, 17B which conform to the ambient temperature
signal S2.
[0032] The map data characteristics are set such that the value of
the duty-ratio data D1 outputted from the map arithmetic operation
part 61 becomes larger corresponding to the lowering of the
inputted temperature. Since the ambient temperature is lower than
the temperature in the inside of the tank 2 in general, when the
flow of the urea water solution U in the inside of the pipe 3 is
stopped, the drive current Y of the larger duty-ratio is supplied
to the heaters 17A, 17B whereby the heating of the pipe 3 and the
return pipe 12 is accelerated. In this manner, the
thermal-maintaining of the pipe 3 and the return pipe 12 can be
performed appropriately depending on the situation, and the
overheating and the refreezing of the pipe 3 and the return pipe 12
can be effectively prevented. In this manner, during a period in
which the liquid supply device 1 is operated, the injection failure
of the urea water solution can be effectively prevented thus
enabling the excellent thermal-maintaining operation.
[0033] Here, in FIG. 2, either one of the duty-ratio data D1 or the
fixed data D2 is selected in response to the thawing and
thermal-maintaining control signal M1. However, even when the
thawing operation of the pipe 3 is performed by another device, it
may be possible to directly supply the duty-ratio data D1 to the
drive current output part 64.
INDUSTRIAL APPLICABILITY
[0034] According to the present invention, it is possible to
smoothly supply the liquid for an exhaust gas post-treatment device
and hence the present invention is useful for improving a liquid
supply device for an exhaust gas post-treatment device.
* * * * *