DE102012209689A1 - Device for ventilating exhaust gas after treatment system of motor car, has valve provided in closed position during engine idle condition, and shifted between passage- and closed positions by hydraulic actuatable actuator - Google Patents

Abstract

The device (2) has a two-way valve (10) provided in a passage position during operation of an internal combustion engine, where reducing agent flows from a conveyor module (4) to a dosing module (6) in the passage position. The valve is provided in a closed position during an idle condition of the internal combustion engine, in which flow of the reducing agent between the conveyor module and the dosing module is prevented. The valve is shifted between the passage- and closed positions by a hydraulic actuatable actuator (12). The reducing agent is selected from urea water solution and Ad Blue (RTM: Diesel exhaust fluid).

Description

State of the art

The invention relates to a device for ventilating an exhaust gas aftertreatment system, with which a freezable operating / auxiliary substance, in particular a reducing agent, is metered into an exhaust gas tract of an internal combustion engine.

The invention also relates to an exhaust aftertreatment system having a delivery module and a metering module.

In motor vehicles with internal combustion engines, a proportion of nitrogen oxides in the exhaust gas must be significantly reduced due to the exhaust gas legislation. To reduce the nitrogen content in the exhaust gas is currently z. B. the SCR method (SCR = Selective Catalytic Reduction) used in which the nitrogen oxides are reduced by using a reducing agent to nitrogen and water. As a reducing agent aqueous systems are used in many cases, such as. As a urea-water solution, such as AdBlue. The reducing agent used, generally in liquid form, is generally stored in a storage tank and conveyed via a delivery module from the tank to a dosing module for introducing the reducing agent into the exhaust gas.

From the DE 10 2010 031 660 For example, in an SCR metering system to shut down the system, it is known to suck the reductant back to protect ice pressure sensitive components when it falls below the freezing point of the reductant which, for example, is -11 ° C in the case of AdBlue. After reducing the system pressure in the pressure line via a relief valve, one or more metering valves are opened, so that air is sucked out of the exhaust tract into the metering module during the opening time. Due to the available volumes, the time for the suck-back process can not be significantly shortened.

Systems are known in which the delivery module pump empties and aerates the metering valve by generating negative pressure. DE 10 2010 030 050 A1 shows an SCR metering system, in which a hydraulic spring accumulator during operation at system pressure stores energy that it releases when switching off the internal combustion engine without power, so that a negative pressure for the extraction of the operating / auxiliary material is generated from the components of the exhaust aftertreatment system. For this purpose, the hydraulic spring accumulator has two chambers separated by a working diaphragm, wherein a first chamber lies in a conveying branch for the operating / auxiliary substance and a second chamber lies in a return branch for the operating / auxiliary substance. If the internal combustion engine is turned off, the electrical line to the battery of the vehicle is interrupted and the delivery unit stops its promotion. An arranged in the conveying branch check valve or an electrically operated valve closes on it and provided in a hydraulic spring storage spring moves the working diaphragm from the position which occupies the working diaphragm at applied system pressure in a position opposite thereto. As a result, a negative pressure is generated in the return branch, which causes exhaust gas is sucked into the metering module, whereby it is ventilated and kept freeze-proof.

Disclosure of the invention

According to the invention, a device for ventilating an exhaust aftertreatment system is provided, with which a freezable operating / auxiliary substance, in particular a reducing agent, is metered into an exhaust tract of an internal combustion engine, comprising a valve, which is located during operation of the internal combustion engine in an open position, in which the operating / Excipient can flow from a delivery module to a dosing and is in flared internal combustion engine in a closed position, in which the operating / auxiliary material between the delivery module and the dosing module can not flow. It is provided that the valve is switchable by means of a hydraulically actuated actuator.

The invention also provides an exhaust aftertreatment system comprising a delivery module and a metering module having such a device for ventilating the exhaust aftertreatment system.

Advantages of the invention

The device according to the invention with the features of the independent claim has the advantage that no separate return branch is provided, but a suck back on the same line is possible over which the operating / auxiliary material is promoted. It is particularly advantageous because the device for ventilation of the exhaust aftertreatment system can be used in areas in which a space is limited available. Thus, no further, for example electrical connections are needed and the device can even be placed in the immediate vicinity of the dosing. Furthermore, it is advantageous that a complete ventilation of the system including the conveyor module is no longer necessary, in cases where the conveyor module is formed ice pressure resistant.

The measures listed in the dependent claims are advantageous Further developments and improvements of the device specified in the independent claim possible.

When stopping the internal combustion engine by means of the hydraulically actuated actuator, the valve is switched to the closed position. As a result, leakage of the delivery module with respect to the metering valve or metering module is very effectively prevented. In the event of a leakage of the delivery module, the metering module or metering valve is wetted by the operating / auxiliary substance, for example by the reducing agent AdBlue, which has a very high creeping ability, since the metering module or metering valve usually sits at the lowest point of the system accumulates in the system remaining and / or introduced after stopping AdBlue on dosing or metering valve. The device for aeration of the exhaust aftertreatment system thus advantageously provides a leakage check valve for all leaking leakage before entering the dosing module. The rather expensive and complex implementation of a zero-leakage valve in the delivery module is thus implemented by a cost-effective zero-leakage valve in front of the metering valve. After shutting down the system, the leakage check valve ideally seals the pressure line with zero leakage.

According to an advantageous embodiment of the hydraulically actuated actuator of the valve is connected via a pressure-loadable control line to the delivery line. In this case, the actuator is actuated hydraulically via a pressure change in the delivery line, which can be effected by a pressure change in the delivery module. It is particularly advantageous that no electrical leads and ground cables must be laid and secured, as would be the case for example with an electrically controlled valve. The valve can be actuated via a pressure build-up or pressure reduction, for example via a suction pressure in the delivery line.

It is particularly advantageous that a closing time or a closing delay of the valve is adjustable. For this purpose, the hydraulically actuable actuator has a storage volume for the operating / auxiliary substance, which can be dimensioned according to the application.

Preferably, a throttle device is also connected upstream of the hydraulically actuable actuator. The time in which the pressure in the storage volume, i. Pressure accumulator of the actuator builds and / or relaxes and so leads, for example, to close the valve is adjustable over the throttle cross-section. It can be provided both manually adjustable throttle devices or readjustable or non-readjustable fixed throttle devices. Thus, the opening time or closing time or opening or closing delay of the valve is adjustable via suitable dimensioning of the throttle device.

According to an advantageous embodiment, a passively switchable valve is connected in parallel with the throttle device. As a result, a quick opening or closing the valve can be made possible. In particular, it is possible in this way to park the vehicle at zero leakage in a very short time.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

Show it

1 1 is a schematic representation of a device for aeration of an exhaust aftertreatment system according to a first embodiment of the invention,

2 a schematic representation of a device for ventilation of an exhaust aftertreatment system according to a second embodiment of the invention and

3 a schematic representation of a device for ventilation of an exhaust aftertreatment system according to a third embodiment of the invention.

Embodiments of the invention

In 1 is a schematic representation of a device 2 for ventilation of an exhaust aftertreatment system shown. The device 2 for ventilation of the exhaust aftertreatment system is between a delivery module 4 and a dosing module 6 arranged, via which an operating / auxiliary substance, in particular a reducing agent, which may be a urea-water solution, is injected into an exhaust tract of an internal combustion engine, in particular upstream of a NO _x catalyst for the reduction of NO _x in the exhaust gas , The conveyor module 4 is usually located in a known manner above a storage tank in which the reducing agent is stored. Between the conveyor module 4 and the dosing module 6 extends a delivery line 8th for the reducing agent to which other systems may be connected, for example, temperature sensors, flow meters and / or filters, which are not shown.

The device 2 for venting the exhaust aftertreatment system comprises a valve 10 . which as a 2/2-way valve 10 is executed, which is a hydraulically actuated actuator 12 is assigned, and a spring element 14 against which the 2/2-way valve 10 is biased. The 2/2-way valve 10 is in 1 shown in a closed position in which there is the delivery line 8th between the conveyor module 4 and the dosing module 6 interrupts. In the illustrated closed position of the 2/2-way valve, the operating / auxiliary substance can not be between the delivery module 4 and the dosing module 6 flow. The closed position is a relaxed state of the spring element 14 assigned. About the hydraulically actuated actuator 12 can be the 2/2-way valve 10 switch to a passage position in which the operating / auxiliary substance via the delivery line 8th from the conveyor module 4 to the dosing module 6 can flow. In the passage position of the 2/2-way valve 10 is the spring element 14 strained and stores potential energy to the 2/2-way valve 10 to return to the closed position when the actuator 12 is no longer operated.

The hydraulically actuated actuator 12 has according to the illustrated embodiment, a housing 11 and one in the case 11 arranged piston 13 on and a connection 17 with a passage opening through which the operating / auxiliary substance in a storage volume 15 of the actuator 12 can occur. When filling the storage volume 15 with the operating / auxiliary substance enters the piston 13 out of the case 11 out and the hydraulically actuated actuator 12 switches the 2/2-way valve 10 ,

The hydraulically actuated actuator 12 is via a pressurizable control line 18 actuated. The control line is to the delivery line 8th connected and via a pressure change in the delivery line 8th actuated. At a branching point 20 this is part of the operating / auxiliary substance from the delivery line 8th branched off and to actuate the hydraulically actuated actuator 12 used. Thus, the device uses 2 for ventilation of the exhaust aftertreatment system for controlling the 2/2-way valve 10 only the delivery line 8th and requires no further connections, in particular no electrical supply lines and can be flexibly installed in exhaust aftertreatment systems.

In the control line 18 is for setting the closing time of the 2/2-way valve 10 after a pressure reduction in the control line 18 and in the promotion line 8th a throttle device 16 intended. The time within which the throttle device 16 in the control line 18 the storage volume 15 the hydraulically actuated actuator 12 deflated, causing the 2/2-way valve to close 10 leads is through a cross section of the throttle device 16 and / or by the storage volume 15 the hydraulically actuated actuator 12 adjustable. In the illustrated embodiment, the throttle device 16 an actuator 19 on, by means of which the cross section of the throttle device 16 manually adjustable. Thus, the closing time can be set for any application.

2 shows a schematic representation of a device 2 for ventilating an exhaust aftertreatment system according to another embodiment of the invention. The device 2 for ventilation of the exhaust aftertreatment system is between the delivery module 4 and the dosing module 6 arranged and includes a 2/2-way valve 10 , the one over a control line 18 hydraulically operated actuator 12 is assigned, and a spring element 14 against which the 2/2-way valve 10 biased, as already related to 1 has been described. Unlike the embodiment according to 1 is in the control line 18 via branches 28 . 34 a bypass 30 to a branch 32 with the throttle device 16 educated. The bypass 30 includes a passively switchable valve, shown here, for example, a check valve 26 , The check valve 26 is with the throttle device 16 connected in parallel and the hydraulically actuated actuator 12 upstream. The illustrated embodiment allows a quick opening of the 2/2-way valve 10 , The storage volume 15 the hydraulically actuated actuator 12 is in the conveying direction 22 preferably over the bypass 30 filled and brought to opening pressure. In the direction of reflux 24 locks the check valve 26 in the bypass 30 and the entire storage volume 15 must be over the branch 32 over the throttle device 16 be reduced, so that there is an adjustable long closing time.

In the embodiment according to 3 is compared to the embodiment according to 2 only the blocking and passage direction of the check valve 26 vice versa, otherwise identical components are shown with the same reference numerals. The check valve 26 is in the bypass branch 30 arranged, which of the control line 18 branches off, leaving the check valve 26 with the throttle device 16 connected in parallel and the hydraulically actuated actuator 12 upstream. At a drop in system pressure in the delivery line 8th or in the control line 18 , or when sucking back the operating / auxiliary substance from the storage volume 15 of the actuator 12 over in the return direction 24 opened check valve 26 flow, making it a quick closing of the 2/2-way valve 10 comes. When switching on, the entire volume must be due to the in the conveying direction 22 locking check valve 26 over the branch 32 with the throttle device 16 flow, so over the cross section of the throttle device 16 set the startup time of the system.

According to further, not shown embodiments of the invention, the hydraulically actuated actuator 12 in the embodiments according to 1 . 2 and 3 in a conventional manner comprise a housing and a diaphragm bellows, wherein the diaphragm bellows separates the housing, for example, in two independent chambers or is designed as a housing wall. When filling the hydraulically actuated actuator with the operating / auxiliary material of the diaphragm bellows is deflected from a rest position and / or elastically deformed, whereby the 2/2-way valve can be actuated via a suitable coupling.

The invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of expert action.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010031660 [0004]
• DE 102010030050 A1 [0005]

Claims (11)

Contraption ( 2 ) for ventilating an exhaust aftertreatment system, with which a freezable operating / auxiliary substance, in particular a reducing agent, is metered into an exhaust tract of an internal combustion engine, comprising a valve ( 10 ), which is in a passage position during operation of the internal combustion engine, in which the operating / auxiliary substance from a conveyor module ( 4 ) to a dosing module ( 6 ) can flow and with flared internal combustion engine in a closed position, in which the operating / auxiliary material between the conveyor module ( 4 ) and the dosing module ( 6 ) can not flow, characterized in that the valve ( 10 ) by means of a hydraulically actuatable actuator ( 12 ) is switchable. Contraption ( 2 ) according to claim 1, characterized in that when stopping the internal combustion engine by means of the hydraulically actuable actuator ( 12 ) the valve ( 10 ) is switched to the closed position. Contraption ( 2 ) according to claim 1 or 2, comprising a to the hydraulically actuable actuator ( 12 ) of the valve ( 10 ) connected, pressurizable control line ( 18 ), via which the hydraulically actuatable actuator ( 12 ) is operable. Contraption ( 2 ) according to claim 3, characterized in that the control line ( 18 ) to a support line ( 8th ) and the hydraulically actuatable actuator ( 12 ) via a pressure change in the delivery line ( 8th ) is operable. Contraption ( 2 ) according to one of the preceding claims, characterized in that the valve ( 10 ) against a spring element ( 14 ) is biased. Contraption ( 2 ) according to one of the preceding claims, characterized in that the hydraulically actuable actuator ( 12 ) a piston ( 13 ) or a diaphragm bellows. Contraption ( 2 ) according to one of the preceding claims, characterized in that the hydraulically actuable actuator ( 12 ) a storage volume ( 15 ) for the operating / auxiliary substance. Contraption ( 2 ) according to one of the preceding claims, characterized in that the hydraulically actuable actuator ( 12 ) a throttle device ( 16 ) is connected upstream. Contraption ( 2 ) according to one of the preceding claims, characterized in that the hydraulically actuable actuator ( 12 ) a passively switchable valve, in particular a check valve ( 26 ), which is in a conveying direction ( 22 ) or in a reflux direction ( 24 ) locks. Contraption ( 2 ) according to claim 8 and claim 9, characterized in that the passively switchable valve, in particular non-return valve ( 26 ) with the throttle device ( 16 ) is connected in parallel. Exhaust gas aftertreatment system with a delivery module ( 4 ) and a dosing module ( 6 ), comprising a device ( 2 ) for ventilation of the exhaust aftertreatment system according to one of claims 1 to 10.

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