Exhaust gas purification system

Details Exhaust gas purification system Exhaust gas purification system

2001-12-18

2004-05-25

Denion, Thomas (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

By means producing a chemical reaction of a component of the...

C060S295000, C222S399000, C222S400700, C285S031000, C285S361000, C285S402000

Reexamination Certificate

active

06739124

ABSTRACT:

CROSS REFERENCE APPLICATIONS
This application claims priority from German application no. 200 21 398.9 filed Dec. 18, 2000.
FIELD OF INVENTION
The present invention relates to an exhaust gas purification system for denoxing exhaust gases (i.e. removing oxides of nitrogen) of a combustion unit on an SCR catalyst utilizing ammonia (NH
3
), additionally introduced into the exhaust gas flow before the SCR catalyst.
BACKGROUND OF THE INVENTION
Apart from carbon monoxide (CO) and hydrocarbons (HC), in particular nitrogen oxides (NO
x
) are among the environmentally harmful, directly emitted primary injurious substances which are generated during operation of internal combustion engines, in particular Diesel engines. Such nitrogen oxides include such compounds as nitric oxide, nitrogen trioxide (N
2
O
3
), dinitrogen tetroxide (N
2
O
4
), nitrogen dioxide (NO2) and trinitrogen tetroxide (N
3
O
4
). The use of three-way catalysts, such as are used in Otto engines and gas engines, cannot be used in the exhaust of Diesel engines due to an excess of oxygen. For this reason, for the reduction of the nitrogen oxides emission in Diesel engines a selectively working SCR catalyst (S
e
lective
C
atalytic
R
eduction catalyst) was developed, in which the expelled nitrogen oxides are reduced to N
2
and H
2
O in the presence of a supplied reducing agent, namely ammonia (NH
3
).
Such exhaust gas purification systems are known, for example, from EP 0 277 765 A1 or EP 0 381 276 A1. The NH
3
is stored as a fluid in a pressure-tight container and connected with the exhaust gas line via a supply line. From the reducing agent container the gaseous NH
3
is tapped, then injected in the required quantity into the exhaust gas flow via a metering valve driven by a control unit. Metering of the NH
3
quantity takes place as a function of the instantaneous operating states of the combustion unit. These patents are incorporated herein by reference.
In these prior known commercially available systems, pressure-tight gas cylinders are employed as reducing agent containers. The containers are connected in conventional manner to the supply line by means of a screw connection. When using such a prior known exhaust gas purification system in a motor vehicle, for example in a commercial motor vehicle, the intent is to provide the employed reducing agent container for reasons of safety, but in particular also for reasons of handling techniques, such that it is not too large. Therefore the reducing agent containers in such exhaust gas purification systems applied in a motor vehicle must be replaced frequently. For reasons of handling techniques, however, for replacing such a container it is not appropriate, and correspondingly time-consuming, if with one or several NH
3
gas cylinders carried on board, first, all connections must be unscrewed and subsequently newly emplaced filled reduction containers must be screwed on. Moreover, in the case of such a conventional connection of prior known containers, it is a disadvantage that the person replacing the reducing agent container by necessity is in the direct proximity of the free end of the supply line so that it is possible that he is in contact with the gaseous NH
3
flowing out of the supply line.
Building on this discussed prior art, the present invention is therefore based on the task of developing further an exhaust gas purification system according to the species described in the introduction, such that the disadvantages demonstrated regarding prior art are minimized if not even avoided.
SUMMARY OF THE INVENTION
This task is solved according to the invention, for one, wherein that at least one reducing agent container is held in a docking device as part of the exhaust gas purification system and, via a coupling device, is connected with the supply line, of which coupling device one coupling part is associated with the docking device and the other coupling part with the container, wherein both coupling parts can be engaged with an axial movement directed toward one another, and the docking device and the container comprise cooperating guide means through which a container under guidance can be brought into its specified position for joining the two coupling parts.
The task is further solved through a system or configuration for holding the reducing agent container(s) in the frame of a replacement container system and connecting it to an exhaust gas purification system such as cited in the introduction, which comprises a container changing system comprising a docking device and a two-part coupling device, the coupling device comprising one coupling part associated with the docking device and the other coupling part associated with at least one reducing agent container which is held in the docking device, wherein the two coupling parts can be engaged with one another. The docking device and the reducing agent container further comprise cooperating guide means, through which the reduction container(s) can be brought into the specified position (under guidance) for engaging the two coupling parts. Furthermore, this task is solved with a reducing agent container for application in an exhaust gas purification system such as cited in the introduction, comprising a cylindrical shell with one coupling part disposed on the head end of the container, while at the foot end handle means are disposed for handling the container for insertion into a docking device and during engagement of the two coupling parts.
The exhaust gas purification system according to the invention comprises a docking device for receiving at least one reducing container. This docking device includes a coupling part, which can be engaged with a second coupling part, associated with the reducing agent container, for the purpose of establishing a fluid connection between the container and the supply line. The two coupling parts are laid out or arranged in the manner of a quick connect coupling and can be engaged with one another via an axial movement, at least as a component, directed toward one another. To connect the two coupling parts, it can therefore be sufficient to simply move the two coupling parts axially toward one another until the specified connection is established. It can also be provided that the axial movement represents only a vectorial component of a movement toward one another of the two coupling parts, in which also a rotational component is included. In such a case the two coupling parts can be engaged for example by a bayonet coupling. The docking device further comprises guide means through which a container can be brought into its specified position for joining the two coupling parts. The guide means can comprise such means which serve for guiding and supporting the container as such and can comprise further guide means which are provided to place the two coupling parts for engagement with one another as specified.
In the case of an exhaust gas purification system equipped with such a docking device, not only can a quick change of the applied reduction container take place, but it is in particular possible to connect through the applied guide means the container(s) to the supply line without anyone needing to directly guide the coupling parts themselves for joining the coupling parts. Consequently, such containers can be connected to the exhaust gas purification system via the docking device whereby the reduction container is handled at its end opposing the coupling part and the person carrying out the container replacement thus is located at a relatively great distance from the two coupling parts which have to be placed for engagement with one another. For this purpose a reducing agent container for such an exhaust gas purification system comprises at its foot end, opposing the coupling part, handle means for handling the reduction container. As a handle can be provided, for example, a ring with grip openings included therein and encircling the base of the container. For this purpose the containers are conveniently held in the horizontal position in the docking device.
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