US20110186153A1 - Metering system for a liquid medium, particularly a urea-water solution - Google Patents
Metering system for a liquid medium, particularly a urea-water solution Download PDFInfo
- Publication number
- US20110186153A1 US20110186153A1 US12/737,200 US73720009A US2011186153A1 US 20110186153 A1 US20110186153 A1 US 20110186153A1 US 73720009 A US73720009 A US 73720009A US 2011186153 A1 US2011186153 A1 US 2011186153A1
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- Prior art keywords
- valve
- metering
- check valve
- metering system
- line
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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- 239000007788 liquid Substances 0.000 title claims abstract description 9
- WTHDKMILWLGDKL-UHFFFAOYSA-N urea;hydrate Chemical compound O.NC(N)=O WTHDKMILWLGDKL-UHFFFAOYSA-N 0.000 title claims description 5
- 230000033001 locomotion Effects 0.000 claims abstract description 10
- 239000003638 chemical reducing agent Substances 0.000 claims description 20
- 238000012423 maintenance Methods 0.000 claims description 19
- 230000009467 reduction Effects 0.000 abstract description 4
- 238000002485 combustion reaction Methods 0.000 abstract description 3
- 238000005086 pumping Methods 0.000 description 21
- 239000007789 gas Substances 0.000 description 7
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- 230000003197 catalytic effect Effects 0.000 description 5
- 238000004891 communication Methods 0.000 description 5
- 235000014676 Phragmites communis Nutrition 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 238000013022 venting Methods 0.000 description 2
- 229920002943 EPDM rubber Polymers 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/206—Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B13/00—Pumps specially modified to deliver fixed or variable measured quantities
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/01—Adding substances to exhaust gases the substance being catalytic material in liquid form
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/14—Arrangements for the supply of substances, e.g. conduits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/14—Arrangements for the supply of substances, e.g. conduits
- F01N2610/1433—Pumps
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/7722—Line condition change responsive valves
- Y10T137/7837—Direct response valves [i.e., check valve type]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/7722—Line condition change responsive valves
- Y10T137/7837—Direct response valves [i.e., check valve type]
- Y10T137/7904—Reciprocating valves
- Y10T137/7922—Spring biased
Definitions
- SCR selective catalytic reduction
- German Patent Disclosure DE 10 2006 012 855 A1 An aqueous urea solution is stored in a tank and metered as needed by a metering pump and with the aid of a metering valve into an exhaust tube of the engine.
- the metering valve known from DE 10 2006 012 855 A1 is pressure-actuated. This means that it opens as soon as a predetermined opening pressure at the inlet to the metering valve is exceeded. As soon as the opening pressure is undershot, the metering valve closes again.
- the pressure-actuated metering valve is a “passive” component, which does not require its own triggering. Signal lines or control lines from a control unit to the metering valve are not required, either.
- a metering system for a liquid medium in particular a liquid reducing agent, such as an aqueous urea-water solution, having a tank, having a metering pump, and having a metering valve, a pressure side of the metering pump and the metering valve communicating with one another through a first line, and the tank and an intake side of the metering pump communicating with one another through a second line, is attained in that a first check valve is provided in the first line.
- a liquid reducing agent such as an aqueous urea-water solution
- the first check valve prevents the first line from emptying between two actuations of the metering valve.
- the consequence of such emptying would be that in the ensuing actuation of the metering pump, the quantity of urea-water solution specified by an engine control unit would not be metered in. As a result, the quality of the exhaust gas posttreatment would suffer, and emissions would rise.
- a reciprocating motion of the metering pump is transmitted at least partially to the valve member of the first check valve.
- the metering pump first executes a pumping stroke and pumps the liquid reducing agent into the first line.
- the valve member of the first check valve opens as soon as the pressure in the metering pump is greater than the opening pressure of the first check valve, and the pumping of reducing agent to the metering valve begins.
- the reciprocating motions of the metering pump and of the valve member are uncoupled from one another, so that the first check valve can perform its function known from the prior art and hydraulically disconnects the first line from the metering pump.
- the coupling of the valve member and the stroke of the metering pump makes venting of the metering system easier.
- a compressible medium such as air or vapor
- the metering pump now pumps fully again, and also, over the course of time, it pushes the vapor bubbles or air bubbles present in the intake line out of the metering system through the metering valve.
- the first check valve is spring-loaded.
- the first check valve is embodied as a double-acting check valve, and that a second valve seat of the first check valve communicates hydraulically with the tank via a connecting line. This prevents an unwanted new opening of the metering valve after the metering pump has been shut off.
- the first check valve When liquid reducing agent is being delivered by the metering pump, the first check valve opens, and the reducing agent from the metering pump reaches the first line. After the pumping and injection of the reducing agent by the metering valve into the exhaust system, the first check valve closes again. As a result of the closure of the metering valve, a pressure surge occurs in the first line, which is reflected by a single-acting check valve and travels back to the metering valve. There, the pressure surge can trip a brief opening of the metering valve. As a consequence, a not-insignificant quantity of the reducing agent is metered unintentionally into the exhaust pipe. This effect increases with increasing closing speed of the metering valve.
- the first check valve is embodied as a double-acting check valve
- the check valve closes a connecting line between the first line and the tank of the metering system. In this position, the metering system behaves no differently from a metering system according to the invention with a single-acting check valve.
- a pressure maintenance valve in particular an adjustable pressure maintenance valve, is provided in the connecting line.
- the opening pressure of the pressure maintenance valve is selected such that it is lower than the opening pressure of the metering valve, since only then can the reflection of pressure surges be reliably avoided.
- the maintenance pressure of the pressure maintenance valve it is possible to suppress the vapor bubble formation inside the first line or inside the metering system and also as a result to further improve the function and the precision with which the reducing agent is metered in and metered.
- FIG. 1 shows the schematic layout of a metering system according to the invention
- FIGS. 2 and 3 show exemplary embodiments of metering systems according to the invention.
- FIG. 1 an internal combustion engine 1 with an exhaust gas posttreatment device 3 is shown highly simplified and schematically.
- the exhaust gas posttreatment device 3 includes an exhaust tube 5 , an oxidation catalytic converter 7 and an SCR catalytic converter 11 .
- the flow direction of the exhaust gas through the exhaust tube 5 is indicated by arrows (without reference numerals).
- a metering valve 13 for the reducing agent is disposed on the exhaust tube 5 , upstream of the SCR catalytic converter 11 .
- the metering valve 13 injects reducing agent as needed into the exhaust tube 5 upstream of the SCR catalytic converter 11 .
- the metering system of the invention includes the metering valve 13 , a metering pump 15 , and a storage container 17 .
- the metering pump 15 is shown in FIG. 1 only as a “black box”. Details of it will be explained below in conjunction with FIGS. 2 and 3 .
- a first line 19 is provided between the metering pump 15 and the metering valve 13 .
- a second line 21 is provided between the tank and the metering pump 15 .
- the sensors disposed in the exhaust system namely an NOX sensor 25 , as well as temperature sensors 23 and 27 .
- These sensors 23 , 25 and 27 communicate with an engine control unit 29 via signal lines (without reference numerals).
- This control unit 29 controls the engine 1 and among other things the metering pump 15 as well.
- the line connection between the control unit 29 and the metering pump 15 is represented by a dashed-line arrow (without a reference numeral) in FIG. 1 .
- FIG. 2 A first exemplary embodiment of a metering system of the invention will be described and explained in conjunction with FIG. 2 . Identical components are provided with the same reference numerals, and what has been said with regard to FIG. 1 applies accordingly.
- the metering valve 13 is schematically shown as a spring-loaded valve.
- the metering pump 15 is embodied as a diaphragm pump with a diaphragm 31 .
- the diaphragm 31 of the metering pump 15 is actuated by an electromagnet, which includes a coil 33 and an armature 35 .
- an electromagnet which includes a coil 33 and an armature 35 .
- the armature 35 moves up in FIG. 2 , and with it the diaphragm 31 also moves upward, and the armature executes a pumping stroke.
- the stroke H is shown in FIG. 2 .
- a first check valve 39 is disposed between a pumping chamber 37 of the metering pump 15 and the first line 19 .
- the first check valve 39 is shown in FIG. 2 as a reed valve, including a valve member 41 and a valve seat 43 .
- the valve member 41 is embodied as an elastic diaphragm comprising plastic, such as EPDM, or metal.
- a spring 44 exerts a force in the closing direction of the first check valve 39 on the valve member 41 .
- the reciprocating motion of the diaphragm 31 is partially transmitted to the valve member 41 via a tappet 45 .
- this second check valve 46 is not spring-loaded. It is often likewise embodied as a reed valve, although in FIGS. 2 and 3 it is shown symbolically as a ball valve.
- the first check valve 39 is embodied as a double-acting check valve and is shown symbolically as a ball valve, although as a rule it is a reed valve or poppet valve.
- the first check valve 39 has not only the first valve seat 43 but a second valve seat 47 as well, whose outlet communicates hydraulically with the tank 17 via a connecting line 49 and the second line 21 .
- valve member 41 lifts away from the first valve 43 and closes the connecting line 49 , because it is pressed sealingly against the second valve seat 47 .
- the hydraulic communication between the pumping chamber 37 and the first line 19 is opened up, and the pumping of reducing agent into the first line 19 begins.
- the pumping stroke in the second exemplary embodiment proceeds in precisely the same way as described in conjunction with the first exemplary embodiment of FIG. 2 .
- the pressure conditions in the first check valve 39 ensure that the valve member 41 is pressed against the first valve seat 43 again, and as a result, the hydraulic communication between the pumping chamber 37 and the first line 19 is interrupted.
- a hydraulic communication is opened between the first line 19 , the connecting line 49 , the second line 21 , and the tank 17 , so that any pressure surges originating in the metering valve 13 proceed to the tank 17 and are dissipated there.
- a pressure maintenance valve 51 is provided in the connecting line 49 .
- the pressure maintenance valve 51 serves to maintain an adjustable minimum pressure in the first line 19 , so that the boiling point of the reducing agent in the first line 19 is raised, and the formation of vapor bubbles is suppressed.
- the opening pressure of the pressure maintenance valve 49 is lower than the opening pressure of the metering valve 13 , so that the closing motion and sealing off of the metering valve 13 are not hindered by the pressure maintenance valve 51 .
- pressure surges whose amplitude is greater than the opening pressure of the pressure maintenance valve 51 can proceed onward virtually unhindered into the tank 17 and can be dissipated there.
- the pressure maintenance valve 51 is adjustable with regard to its maintenance pressure, so that it can be adjusted to suit the prevailing operating conditions. As a result, it is possible, for instance after the shutoff of the engine, to change the maintenance pressure, so that the first line 19 is completely pressure-relieved, and as a result, the metering valve 13 is also completely tight over a longer period of time. If the risk of vapor bubble formation arises during operation of the engine, the maintenance pressure of the pressure maintenance valve 51 can be increased accordingly.
- FIG. 3 b a block circuit diagram of the exemplary embodiment of FIG. 3 a is shown.
- various pressure sensors 53 . 1 , 53 . 2 and 53 . 3 are shown, which are each installed as needed and connected to the control unit 29 .
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Combustion & Propulsion (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
The invention relates to a dosing system for a liquid reduction medium enabling precise dosing of the reduction medium in the exhaust gas system of an internal combustion engine. This is carried out particularly by using a quick and safe closing of a pressure-actuated dosing valve. Simultaneously, the dosing system according to the invention also enables the dissipation of the pressure impulses resulting due to the closing movement of the dosing valve.
Description
- The emissions limit values for nitrogen oxides, in motor vehicles whose weight exceeds a certain limit, require exhaust gas posttreatment devices, which perform selective catalytic reduction (SCR) of the nitrogen oxides contained in the raw emissions from the internal combustion engine. This so-called SCR method for exhaust gas cleaning is known from the prior art, and a detailed explanation of the chemical processes taking place in this method can therefore be dispensed with.
- One example of this kind of exhaust gas posttreatment device is known from German Patent Disclosure DE 10 2006 012 855 A1. In it, an aqueous urea solution is stored in a tank and metered as needed by a metering pump and with the aid of a metering valve into an exhaust tube of the engine. The metering valve known from DE 10 2006 012 855 A1 is pressure-actuated. This means that it opens as soon as a predetermined opening pressure at the inlet to the metering valve is exceeded. As soon as the opening pressure is undershot, the metering valve closes again.
- The pressure-actuated metering valve is a “passive” component, which does not require its own triggering. Signal lines or control lines from a control unit to the metering valve are not required, either.
- It is the object of the invention to further develop a metering system of the type defined at the outset such that the consumption properties, especially the precision with which reducing agent is metered into the exhaust tube, are improved. Moreover, the tightness of the metering valve should be increased, both during operation and after the shutoff of the engine.
- This object is attained according to the invention in a metering system for a liquid medium, in particular a liquid reducing agent, such as an aqueous urea-water solution, having a tank, having a metering pump, and having a metering valve, a pressure side of the metering pump and the metering valve communicating with one another through a first line, and the tank and an intake side of the metering pump communicating with one another through a second line, is attained in that a first check valve is provided in the first line.
- The first check valve prevents the first line from emptying between two actuations of the metering valve. The consequence of such emptying would be that in the ensuing actuation of the metering pump, the quantity of urea-water solution specified by an engine control unit would not be metered in. As a result, the quality of the exhaust gas posttreatment would suffer, and emissions would rise.
- In a further advantageous feature of the invention, it is provided that a reciprocating motion of the metering pump is transmitted at least partially to the valve member of the first check valve.
- This means that beginning at a state of repose of the metering pump, the metering pump first executes a pumping stroke and pumps the liquid reducing agent into the first line. In a pumping stroke, the valve member of the first check valve opens as soon as the pressure in the metering pump is greater than the opening pressure of the first check valve, and the pumping of reducing agent to the metering valve begins.
- As a result of the transmission according the invention of the reciprocating motion of the metering pump to the valve member, it is in fact ensured that the first check valve remains open during the intake stroke, regardless of the pressure conditions. As a consequence, a predetermined quantity of urea-water solution is reaspirated from the first line back into the metering pump, so that a controlled, rapid pressure reduction takes place in the first line and in the metering valve. As a result, the metering valve closes quickly and tightly, so that the metering of the reducing agent takes place with greater precision.
- Just before the metering pump has reached its outset point, and the stroke of the metering pump is equal to zero, the reciprocating motions of the metering pump and of the valve member are uncoupled from one another, so that the first check valve can perform its function known from the prior art and hydraulically disconnects the first line from the metering pump.
- Finally, the coupling of the valve member and the stroke of the metering pump makes venting of the metering system easier. When a compressible medium, such as air or vapor, is located in a pumping chamber of the metering pump, it can be ensured by the compulsory opening of the first check valve that the air or vapor located in the pumping chamber of the metering pump is expelled into the first line, and as a result venting of the metering pump takes place. As soon as there is only liquid reducing agent present in the metering pump, the metering pump now pumps fully again, and also, over the course of time, it pushes the vapor bubbles or air bubbles present in the intake line out of the metering system through the metering valve.
- To achieve secure closure and better operating performance, it is also provided that the first check valve is spring-loaded.
- In a further feature of the invention, it is also provided that the first check valve is embodied as a double-acting check valve, and that a second valve seat of the first check valve communicates hydraulically with the tank via a connecting line. This prevents an unwanted new opening of the metering valve after the metering pump has been shut off.
- When liquid reducing agent is being delivered by the metering pump, the first check valve opens, and the reducing agent from the metering pump reaches the first line. After the pumping and injection of the reducing agent by the metering valve into the exhaust system, the first check valve closes again. As a result of the closure of the metering valve, a pressure surge occurs in the first line, which is reflected by a single-acting check valve and travels back to the metering valve. There, the pressure surge can trip a brief opening of the metering valve. As a consequence, a not-insignificant quantity of the reducing agent is metered unintentionally into the exhaust pipe. This effect increases with increasing closing speed of the metering valve.
- Now if the first check valve is embodied as a double-acting check valve, then during the pumping of the metering pump, the check valve closes a connecting line between the first line and the tank of the metering system. In this position, the metering system behaves no differently from a metering system according to the invention with a single-acting check valve.
- However, once the pumping stroke of the metering pump has ended, the valve member of the double-acting check valve is pressed back into the valve seat again, and the hydraulic communication between the metering pump and the metering valve is interrupted. Simultaneously, via the connecting line, a hydraulic communication is made between the first line and the pressureless tank, so that a pressure surge originating at the metering valve is not reflected at the first check valve but rather travels to the tank and is dissipated there. As a result, unwanted after-dribbles inside the metering system that are caused by pressure surges are avoided.
- In a further advantageous feature of the invention, it is provided that a pressure maintenance valve, in particular an adjustable pressure maintenance valve, is provided in the connecting line. The opening pressure of the pressure maintenance valve is selected such that it is lower than the opening pressure of the metering valve, since only then can the reflection of pressure surges be reliably avoided. However, because of the maintenance pressure of the pressure maintenance valve, it is possible to suppress the vapor bubble formation inside the first line or inside the metering system and also as a result to further improve the function and the precision with which the reducing agent is metered in and metered.
- Further advantages and advantageous features of the invention can be learned from the ensuing drawings, the description, and the claims. All the characteristics disclosed in the drawings, their description, and the claims can be essential to the invention both individually and in arbitrary combination with one another.
-
FIG. 1 shows the schematic layout of a metering system according to the invention; and -
FIGS. 2 and 3 show exemplary embodiments of metering systems according to the invention. - In
FIG. 1 , aninternal combustion engine 1 with an exhaust gas posttreatment device 3 is shown highly simplified and schematically. The exhaust gas posttreatment device 3 includes anexhaust tube 5, an oxidation catalytic converter 7 and an SCRcatalytic converter 11. The flow direction of the exhaust gas through theexhaust tube 5 is indicated by arrows (without reference numerals). To supply the SCRcatalytic converter 11 with reducing agent, ametering valve 13 for the reducing agent is disposed on theexhaust tube 5, upstream of the SCRcatalytic converter 11. Themetering valve 13 injects reducing agent as needed into theexhaust tube 5 upstream of the SCRcatalytic converter 11. - The metering system of the invention includes the
metering valve 13, ametering pump 15, and astorage container 17. Themetering pump 15 is shown inFIG. 1 only as a “black box”. Details of it will be explained below in conjunction withFIGS. 2 and 3 . - Between the
metering pump 15 and themetering valve 13, afirst line 19 is provided. Between the tank and themetering pump 15, asecond line 21 is provided. - For the sake of completeness, reference should also be made to the sensors disposed in the exhaust system, namely an
NOX sensor 25, as well astemperature sensors sensors engine control unit 29 via signal lines (without reference numerals). Thiscontrol unit 29 controls theengine 1 and among other things themetering pump 15 as well. The line connection between thecontrol unit 29 and themetering pump 15 is represented by a dashed-line arrow (without a reference numeral) inFIG. 1 . - A first exemplary embodiment of a metering system of the invention will be described and explained in conjunction with
FIG. 2 . Identical components are provided with the same reference numerals, and what has been said with regard toFIG. 1 applies accordingly. Themetering valve 13 is schematically shown as a spring-loaded valve. - The
metering pump 15 is embodied as a diaphragm pump with adiaphragm 31. Thediaphragm 31 of themetering pump 15 is actuated by an electromagnet, which includes acoil 33 and anarmature 35. When current is supplied to thecoil 33, thearmature 35 moves up inFIG. 2 , and with it thediaphragm 31 also moves upward, and the armature executes a pumping stroke. The stroke H is shown inFIG. 2 . The position of repose of thediaphragm 31 and of thearmature 35 shown inFIG. 2 corresponds to a stroke H=0. - A
first check valve 39 is disposed between a pumpingchamber 37 of themetering pump 15 and thefirst line 19. Thefirst check valve 39 is shown inFIG. 2 as a reed valve, including avalve member 41 and avalve seat 43. In these reed valves, thevalve member 41 is embodied as an elastic diaphragm comprising plastic, such as EPDM, or metal. Aspring 44 exerts a force in the closing direction of thefirst check valve 39 on thevalve member 41. - The reciprocating motion of the
diaphragm 31 is partially transmitted to thevalve member 41 via atappet 45. This happens as a result of the fact that in the position of repose of thediaphragm 31, and with thefirst check valve 39 closed, thetappet 45 does not rest on thediaphragm 31. - Between the end of the
tappet 45 toward thediaphragm 31 and thediaphragm 31 itself, there is a distance HMIN in this situation. As soon as the stroke H is greater than HMIN, the diaphragm, with the aid of thetappet 45, lifts thevalve member 41 from thevalve seat 43. This coupling of thevalve member 41 with the stroke H of thediaphragm 31 of the metering pump causes thefirst check valve 39 to remain open for a long time during the intake stroke, regardless of the pressure conditions in thefirst line 19 and in thepumping chamber 37. As a consequence, because of the suction motion of thediaphragm 31, some of the reducing agent located in thefirst line 19 is reaspirated back into the pumpingchamber 37. As a result, a pressure reduction takes place in theline 19, and themetering valve 13 closes quickly and tightly. - Between the pumping
chamber 37 and thesecond line 21, there is asecond check valve 46, which prevents reducing agent from being able to flow back out of the pumpingchamber 37 into thesecond line 21 and thetank 17 during the pumping stroke of themetering pump 15. As a rule, thissecond check valve 46 is not spring-loaded. It is often likewise embodied as a reed valve, although inFIGS. 2 and 3 it is shown symbolically as a ball valve. - In
FIG. 3 , a further exemplary embodiment of a metering system of the invention is shown. In this exemplary embodiment, thefirst check valve 39 is embodied as a double-acting check valve and is shown symbolically as a ball valve, although as a rule it is a reed valve or poppet valve. Thefirst check valve 39 has not only thefirst valve seat 43 but asecond valve seat 47 as well, whose outlet communicates hydraulically with thetank 17 via a connectingline 49 and thesecond line 21. As soon as themetering pump 15 begins to pump reducing agent, the pressure in thepumping chamber 37 rises above the pressure prevailing in thefirst line 19. As a consequence, thevalve member 41 lifts away from thefirst valve 43 and closes the connectingline 49, because it is pressed sealingly against thesecond valve seat 47. At the same time, the hydraulic communication between the pumpingchamber 37 and thefirst line 19 is opened up, and the pumping of reducing agent into thefirst line 19 begins. The pumping stroke in the second exemplary embodiment proceeds in precisely the same way as described in conjunction with the first exemplary embodiment ofFIG. 2 . - Now once the pumping has ended and the
diaphragm 31 has returned to its outset position, the pressure conditions in thefirst check valve 39 ensure that thevalve member 41 is pressed against thefirst valve seat 43 again, and as a result, the hydraulic communication between the pumpingchamber 37 and thefirst line 19 is interrupted. At the same time, a hydraulic communication is opened between thefirst line 19, the connectingline 49, thesecond line 21, and thetank 17, so that any pressure surges originating in themetering valve 13 proceed to thetank 17 and are dissipated there. - Optionally, a
pressure maintenance valve 51 is provided in the connectingline 49. Thepressure maintenance valve 51 serves to maintain an adjustable minimum pressure in thefirst line 19, so that the boiling point of the reducing agent in thefirst line 19 is raised, and the formation of vapor bubbles is suppressed. Advantageously, the opening pressure of thepressure maintenance valve 49 is lower than the opening pressure of themetering valve 13, so that the closing motion and sealing off of themetering valve 13 are not hindered by thepressure maintenance valve 51. Moreover, pressure surges whose amplitude is greater than the opening pressure of thepressure maintenance valve 51 can proceed onward virtually unhindered into thetank 17 and can be dissipated there. - In an especially advantageous feature of the invention, the
pressure maintenance valve 51 is adjustable with regard to its maintenance pressure, so that it can be adjusted to suit the prevailing operating conditions. As a result, it is possible, for instance after the shutoff of the engine, to change the maintenance pressure, so that thefirst line 19 is completely pressure-relieved, and as a result, themetering valve 13 is also completely tight over a longer period of time. If the risk of vapor bubble formation arises during operation of the engine, the maintenance pressure of thepressure maintenance valve 51 can be increased accordingly. - In
FIG. 3 b, a block circuit diagram of the exemplary embodiment ofFIG. 3 a is shown. In addition, various pressure sensors 53.1, 53.2 and 53.3 are shown, which are each installed as needed and connected to thecontrol unit 29.
Claims (21)
1-10. (canceled)
11. A metering system for a liquid medium, in particular a liquid reducing agent, such as an aqueous urea-water solution the metering system, having a tank, a metering pump, and a metering valve, a pressure side of the metering pump and the metering valve communicating with one another through a first line, and the tank and an intake side of the metering pump communicating with one another through a second line, wherein a first check valve is provided in the first line.
12. The metering system as defined by claim 11 , wherein a reciprocating motion of the metering pump is transmitted at least partially to a valve member of the first check valve.
13. The metering system as defined by claim 12 , wherein the metering pump includes a diaphragm and the reciprocating motion of the diaphragm is transmitted at least partially to the valve member of the first check valve.
14. The metering system as defined by claim 13 , wherein the valve member of the first check valve is lifted from a first valve seat as soon as the reciprocating motion of the metering pump exceeds a minimum stroke.
15. The metering system as defined by claim 11 , wherein the first check valve is spring-loaded.
16. The metering system as defined by claim 12 , wherein the first check valve is spring-loaded.
17. The metering system as defined by claim 13 , wherein the first check valve is spring-loaded.
18. The metering system as defined by claim 14 , wherein the first check valve is spring-loaded.
19. The metering system as defined by claim 11 , wherein the first check valve is embodied as a double-acting check valve, and a second valve seat of the first check valve communicates hydraulically with the tank or the intake side of the metering pump via a connecting line.
20. The metering system as defined by claim 18 , wherein the first check valve is embodied as a double-acting check valve, and a second valve seat of the first check valve communicates hydraulically with the tank or the intake side of the metering pump via a connecting line.
21. The metering system as defined by claim 19 , wherein a pressure maintenance valve, in particular an adjustable pressure maintenance valve, is provided, in the connecting line.
22. The metering system as defined by claim 20 , wherein a pressure maintenance valve, in particular an adjustable pressure maintenance valve, is provided in the connecting line.
23. The metering system as defined by claim 11 , wherein a second check valve is provided in the second line.
24. The metering system as defined by claim 12 , wherein a second check valve is provided in the second line.
25. The metering system as defined by claim 13 , wherein a second check valve is provided in the second line.
26. The metering system as defined by claim 11 , wherein the metering valve is pressure-actuated.
27. The metering system as defined by claim 12 , wherein the metering valve is pressure-actuated.
28. The metering system as defined by claim 13 , wherein the metering valve is pressure-actuated.
29. The metering system as defined by claim 11 , wherein the metering pump is actuated by a final control element of an actuator, in particular by an armature of an electromagnet.
30. The metering system as defined by claim 12 , wherein the metering pump is actuated by a final control element of an actuator, in particular by an armature of an electromagnet.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102008002467A DE102008002467A1 (en) | 2008-06-17 | 2008-06-17 | Dosing system for a liquid medium, in particular urea-water solution |
DE102008002467.8 | 2008-06-17 | ||
PCT/EP2009/054799 WO2009153085A1 (en) | 2008-06-17 | 2009-04-22 | Dosing system for a liquid medium, particularly a urea-water solution |
Publications (1)
Publication Number | Publication Date |
---|---|
US20110186153A1 true US20110186153A1 (en) | 2011-08-04 |
Family
ID=40886826
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/737,200 Abandoned US20110186153A1 (en) | 2008-06-17 | 2009-04-22 | Metering system for a liquid medium, particularly a urea-water solution |
Country Status (6)
Country | Link |
---|---|
US (1) | US20110186153A1 (en) |
EP (1) | EP2294294B1 (en) |
CN (1) | CN102066709A (en) |
AT (1) | ATE546622T1 (en) |
DE (1) | DE102008002467A1 (en) |
WO (1) | WO2009153085A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150377103A1 (en) * | 2013-02-18 | 2015-12-31 | Continental Automotive Gmbh | Method for heating a delivery device |
US11365664B2 (en) | 2018-10-10 | 2022-06-21 | Vitesco Technologies GmbH | Method for controlling a reflux valve and exhaust system |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102010030860A1 (en) * | 2010-07-02 | 2012-01-05 | Robert Bosch Gmbh | Method for operating reducing agent dosing system for selective catalytic reduction catalyst-converter in exhaust line of combustion engine of motor car, involves actuating metering valve for dosing certain dosage amount into exhaust line |
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DE102004011123A1 (en) * | 2003-09-02 | 2005-03-31 | Hydraulik-Ring Gmbh | Pump for conveying an exhaust aftertreatment medium, in particular a urea-water solution, for diesel engines |
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2008
- 2008-06-17 DE DE102008002467A patent/DE102008002467A1/en not_active Withdrawn
-
2009
- 2009-04-22 US US12/737,200 patent/US20110186153A1/en not_active Abandoned
- 2009-04-22 CN CN200980123060XA patent/CN102066709A/en active Pending
- 2009-04-22 EP EP09765665A patent/EP2294294B1/en not_active Not-in-force
- 2009-04-22 AT AT09765665T patent/ATE546622T1/en active
- 2009-04-22 WO PCT/EP2009/054799 patent/WO2009153085A1/en active Application Filing
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US2456566A (en) * | 1946-11-18 | 1948-12-14 | Shell Dev | Reverse flow by-pass valve |
US3805825A (en) * | 1972-02-22 | 1974-04-23 | Steinen Mfg Co | Unitary pneumatic flow director |
US4549517A (en) * | 1982-12-13 | 1985-10-29 | Mikuni Kogyo Kabushiki Kaisha | Fuel supply device for internal combustion engines |
US5031661A (en) * | 1988-07-08 | 1991-07-16 | Buckner, Inc. | Double check valve backflow preventer assembly |
US5390696A (en) * | 1991-10-17 | 1995-02-21 | Dowty Aerospace Gloucester Limited | Pressure relief valve |
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US6209315B1 (en) * | 1998-04-30 | 2001-04-03 | Siemens Akteingesellschaft | Method and device for exhaust gas after-treatment in an internal combustion engine equipped with an SCR catalyst |
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US20070020123A1 (en) * | 2003-09-02 | 2007-01-25 | Hydraulik-Ring Gmbh | Pump for conveying an exhaust gas aftertreatment medium particularly a urea-water solution, for diesel engines |
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US20150377103A1 (en) * | 2013-02-18 | 2015-12-31 | Continental Automotive Gmbh | Method for heating a delivery device |
US9920672B2 (en) * | 2013-02-18 | 2018-03-20 | Continental Automotive Gmbh | Method for heating a delivery device |
US11365664B2 (en) | 2018-10-10 | 2022-06-21 | Vitesco Technologies GmbH | Method for controlling a reflux valve and exhaust system |
Also Published As
Publication number | Publication date |
---|---|
ATE546622T1 (en) | 2012-03-15 |
EP2294294B1 (en) | 2012-02-22 |
EP2294294A1 (en) | 2011-03-16 |
CN102066709A (en) | 2011-05-18 |
WO2009153085A1 (en) | 2009-12-23 |
DE102008002467A1 (en) | 2009-12-24 |
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Legal Events
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AS | Assignment |
Owner name: ROBERT BOSCH GMBH, GERMANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:VOGT, GUENTHER;LOESCH, STEFAN;BASAN, CHRISTIAN;REEL/FRAME:026189/0912 Effective date: 20101217 |
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |