Power plants – Internal combustion engine with treatment or handling of... – By means producing a chemical reaction of a component of the...
Reexamination Certificate
1999-12-24
2001-05-01
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...
C060S283000, C060S295000, C220S562000, C220S023870, C220S564000, C220S905000
Reexamination Certificate
active
06223526
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel storage tank, and more particularly, to a fuel storage tank having separate compartments for fuel and a reducing agent.
2. Description of Related Art
Using a reducing agent in an exhaust gas purification system is well known to those skilled in the art. A typical such system is discussed in a Siemens Aktiengesellschaft pamphlet entitled “SiNOx Nitrogen Oxide Reduction for Stationary Diesel Engines,” Order No. A96001-U91-A232, Siemens A G, Bereich Energieerzeugung (KWU), Freyeslebenstra&bgr;e 1, 91058 Erlangen, Germany (1994). This system is based on the SCR (Selective Catalytic Reduction) method, which makes use of the fact that nitrogen oxides are converted into nitrogen and water in the presence of urea and suitable catalysts. For this purpose, the diesel engine exhaust gases are passed through an SCR catalytic device which is integrated into the engine exhaust line and into which the reducing agent is introduced in a precisely metered manner.
In a vehicle exhaust gas purification system, it is necessary to provide a tank for the reducing agent. Typically, the reducing agent is stored in a separate storage container or tank spaced from the primary vehicle fuel tanks. A solid reducing agent, such as urea, is dissolved in a liquid, for example, water, for various reasons, among them to facilitate its introduction in precisely metered amounts. Such aqueous solutions of reducing agents crystalize and solidify at relatively high temperatures. For example, a 32.5% urea/water solution solidifies at −11° C. (about 14° F.). If the reducing agent solution freezes, it cannot be pumped from the storage tank and used to purify the engine exhaust.
The need to provide for storage of the reducing agent presents particular problems in a vehicle. First, a separate space must be made available in the vehicle. Then, a separate tank must be provided and brackets and other suitable mounting structure must be provided on the tank and in the vehicle to secure the tank within the space. Using vehicle space to accommodate the reducing agent storage tank reduces the amount of space available for other purposes, notably vehicle payload, and requires moving other vehicle components. Accordingly, a great deal of effort must be devoted to designing a storage tank that uses vehicle space as efficiently as possible and that simplifies mounting the storage tank.
SUMMARY OF THE INVENTION
The present invention relates to a structural unit for storing fuel for an internal combustion engine having an exhaust gas purification system, wherein the structural unit includes space for a reducing agent used in the purification system.
It is an object of the invention to provide a fuel container in such a way that its fastening and the fastening of a container for a reducing agent are simplified.
This object is achieved in accordance with the invention by combining the fuel container and the reducing agent container into a structural unit, so that the structural unit can be mounted as a whole to, say, a vehicle, thus simplifying the mounting thereof.
Therefore, the present invention avoids the necessity of mounting an additional tank for the reducing agent by providing an embodiment particularly useful for a vehicle, in which the fuel tank and the reducing agent tank are connected to form a single structural unit which can be fastened as if the two tanks were a single tank. Combining the two hitherto separate tanks makes it possible efficiently to utilize the installation space, which in a vehicle is confined, and mounting becomes particularly simple.
At the same time, the risk that the reducing agent solution will freeze is counteracted because the area of the reducing agent tank walls in direct contact with the ambient surroundings is reduced, as compared with the previous two-tank structure. In addition, the single unit can be constructed so that the fuel in the fuel tank will be in contact with at least one wall of the reducing agent space, or even so that the fuel tank surrounds the reducing agent tank, and heat in the fuel will be transferred to the reducing agent through the contiguous walls. This structure makes it possible to thaw a reducing agent that may have already frozen in its tank.
In furtherance of those and other objects of the present invention, a structural unit for holding fuel for an internal combustion engine having an exhaust gas purification system using a reducing agent comprises a fuel space for holding the fuel, and a reducing agent space for holding the reducing agent, the reducing agent space having at least one common wall with the fuel space, wherein the common wall has a predetermined thermal conductivity promoting heat transfer between the fuel space and the reducing agent space.
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“SiNOx Nitrogen Oxide Reduction for Stationary Diesel Engines,” Order No. A96001-U91-A232, Siemens AG, Bereich Energieerzeugung (KWU), Freyeslebenstrasse 1, 91058 Erlangen, Germany (1994).
Internationaler Recherchenbericht (International Search Report) in PCT/DE98/01639, Jun. 11, 1998.
International Preliminary Examination Report in PCT/DE98/01639, Oct. 11, 1999.
Hofmann Lothar
Pajonk Gunther
Weigl Manfred
Wissler Gerhard
Denion Thomas
Quinlan, P.C. David M.
Siemens Aktiengesellschaft
Tran Binh
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