Patent Application
20100199647
The present invention relates generally to simultaneously heating engine fluids and filtering the fluids, and more particularly to heated urea strainers for diesel engines.
Diesel engines are typically required by law to incorporate a method for reducing nitrous-oxide (NOx) emissions. To reduce the amount of NOx emitted, many diesel engines include what is known as Selective Catalytic Reduction (SCR) system. In an SCR system, a solution of urea and water is injected into a catalytic converter, which is part of the emission control system of a diesel engine. When the urea-water solution interacts with the NOx, the NOx is converted into nitrogen gas (N2) and water (H2O).
The SCR system therefore requires a urea delivery system whereby the urea may be transferred from a urea tank to the catalytic converter when necessary. However, urea freezes at −11° C. In many parts of the world in which diesel engines are used, typical winter temperatures can dip below −25° C. Thus, a method for melting urea so that it may be injected into a catalytic converter while in extreme weather conditions is necessary. Currently, the predominant method for melting urea in an SCR system involves a coil heating element.
As recognized herein, it is unfortunately the case that the above-mentioned coil heating element requires a high current draw from the diesel engine system, consuming energy that would be used elsewhere in the diesel engine system. Further, the present application recognizes that existing coils to melt urea are placed in a less than optimal position in terms of efficiency. As understood herein, a heating element should be positioned as close as possible to a urea strainer.
Accordingly, a system includes a urea tank and a strainer through which urea from the tank passes to an emission control system of a diesel engine. At least portions of the strainer can be heated to heat urea passing through the strainer.
The portions may include wires that may criss-cross each other. The strainer may be disc-shaped, and the strainer removes impurities from urea passing therethrough. Thus, the wires may be juxtaposed with material in a mesh to remove impurities from urea. An electrical connector can be provided that is configured for engaging a source of electricity. The connector is electrically connected to the wires.
In another aspect, an apparatus includes a strainer engageable with a urea tank associated with a diesel engine for chemically reacting with nitrogen oxide. The strainer includes plural elements removing impurities from urea passing therethrough, with at least some elements being heatable by electricity to heat urea. An electrical connector is configured for engaging a source of electricity. The connector is electrically connected to at least some of the elements.
In another aspect, a method includes removing impurities from urea and heating the urea as the impurities are being removed therefrom.
The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which:
The present invention is intended for application in automotive vehicle systems and will be described in that context. It is to be understood, however, that the present invention could also be applied in other fuel delivery applications.
Beginning initially with
Attached to the catalytic converter 16 is a Selective Catalytic Reduction (SCR) system 18. The purpose of the SCR system 18 is to reduce nitrous oxide (NOx) emissions created by the diesel engine 12 into nitrogen gas (N2) and water (H20). The SCR system 18 accomplishes this by injecting urea into NOx produced by the catalytic converter 16. When the urea interacts with the NOx, the NOx is converted into N2 and H2O.
Thus, the SCR system 18 requires a urea delivery system 20. The urea delivery system 20 includes a urea tank 22 where urea may be stored, and a urea strainer 24 which, in accordance with principles explained further below, is made up of an electrically resistive mesh composition capable of both filtering and melting urea. Further, the strainer 24 has an energy source 26 which provides energy required by the strainer 24 to melt urea in the tank 22. The energy source 26 may be the electrical distribution system of a vehicle and may include a battery.
Further still, the catalytic converter 16 can be fluidly connected to a water tank 28. The water tank 28 may receive H2O from the catalytic converter 16. Lastly, a muffler 30 is connected to the catalytic converter 16. Remaining emissions from the treated effluent of the catalytic converter 16, e.g., N2, may travel to the muffler 30, where the muffler 30 may then release the remaining emissions from the diesel engine system 10.
Moving to
As set forth further below, the strainer in the housing 34 is at least partially composed of overlapping wires capable of being heated and cooled and may be submergible in liquid. The wires at least partially composing the strainer 34 will be discussed in further detail in
Continuing with
Additional details of the assembly 32 are shown in
Further still, the wires 52 may be excited by electricity from the connector 38 to warm urea. Thus, in its heated state, the strainer melts frozen urea at the point where the urea is filtered. Further, an external temperature sensor located on a vehicle in a non-limiting embodiment may be used to determine when current should be sent from the power source to the mesh 50 to melt frozen urea.
Moreover, the maximum temperature to which the strainer may be heated may vary depending on the materials composing both the mesh 50 the strainer so as to not damage either the strainer mesh 50. Regardless, the position of the strainer relative to a urea tank optimizes energy conservation by reducing the electrical draw required to heat frozen urea in a urea tank.
It is to be understood that the present non-limiting embodiment may be used in other applications other than the filtering of urea. The present invention may be used in conjunction with diesel filtration systems or windshield wiper filtration systems, for example.
While the particular HEATED UREA STRAINER FOR DIESEL ENGINE is herein shown and described in detail, it is to be understood that the subject matter which is encompassed by the present invention is limited only by the claims. For example, in addition to the above connection mechanisms, other quick connect/quick disconnect type of mechanisms may be used.
