Fluid heating device and exhaust gas purifying apparatus

Abstract

A fluid heating device includes a heating part and a plurality of heat transfer sections. The heating part is disposed in a fluid stored in a container and is elongated in an axial direction for heating the fluid between a lower portion and an upper portion of the container by being supplied with electricity. The heat transfer sections arranged along the axial direction of the heating part. Each of the heat transfer sections has a plate shape extending from the heating part to a radial outside of the heating part approximately perpendicularly to the axial direction of the heating part.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is based on Japanese Patent Application No. 2007-110689 filed on Apr. 19, 2007, the content of which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a fluid heating device and an exhaust gas purifying apparatus including the fluid heating device.[0004]2. Description of the Related Art[0005]Conventionally, an exhaust gas purifying apparatus using a urea reducing catalyst, such as a urea SCR (selective catalytic reduction) system, is suitably used for reducing nitrogen oxide (NOx) in exhaust gas from a vehicle engine. In an example of the conventional urea SCR system 9 shown in FIG. 9, a SCR catalyst 620 is disposed in an exhaust pipe 60. The SCR catalyst 620 reduces urea selectivity by an action of a reducing agent. An injection valve 40 is disposed on an inlet side of the SCR catalyst 620, for supplying a urea aqueous solut...

AI Technical Summary

Benefits of technology

[0011]It is an object of the present invention to provide a fluid heating device that has a high thermal efficiency with a simple structure. Another object of the invention is to provide an exhaust gas purifying apparatus for purifying exhaust gas from an engine that can stably supply a reducing agent to exhaust gas even just after the engine is started in a low temperature environment.

[0013]When the heating part is supplied with electricity, heat of the heating part is transferred to the heat transfer sections. Thus, the fluid is heated by the heat transfer sections in addition to the heating part, and thereby a frozen fluid in the container can be melted rapidly.

[0015]When the heating pad is supplied with electricity, a flow of the fluid is generated due to a thermal conviction, and the fluid flows spirally along the spiral shape of the heat transfer section. Thus, the fluid in the container is stirred and a frozen fluid is melted effectively.

[0017]The exhaust gas purifying apparatus can stably supply the reducing agent to exhaust gas even just after the engine is started in a low temperature environment.

Problems solved by technology

However, just after starting the engine, a temperature of the engine as a heat source is low.

Thus, a temperature of a coolant as the heat transfer medium is also low and may not have enough heat quantity to melt the liquid reducing agent.

However, the exhaust gas purifying apparatus has a complicated structure.

Additionally, the urea aqueous solution in the sub tank may have different concentration with that in the main tank, and a concentration of the urea aqueous solution supplied to exhaust gas may be unstable.

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