DEF thawing apparatus and method for diesel engine SCR systems

A Diesel Exhaust Fluid Thawing Apparatus of a vehicle having an engine, an Engine Control Module connected to the engine and configured to control the engine, and an exhaust system connected to the engine and having an SCR catalytic device, comprising:

• a Diesel Exhaust Fluid injection system connected to the exhaust system upstream of the SCR catalytic device, and further connected to the Engine Control Module;
• a Diesel Exhaust Fluid tank connected to the Diesel Exhaust Fluid injection system;
• an exhaust pipe branch connected to the exhaust system;
• and
• a heat exchanging apparatus connected to the exhaust pipe branch and configured to exchange heat from exhaust gas within the exhaust pipe branch to the Diesel Exhaust Fluid in the Diesel Exhaust Fluid tank;
• an exhaust gas control valve located in the exhaust pipe branch and being connected to the Engine Control Module;
• the heat exchanging apparatus further comprising:
• an exhaust gas to Diesel Exhaust Fluid heat exchanger located at least partially within the Diesel Exhaust Fluid tank;
• at least one exhaust temperature sensor connected to the Engine Control Module and being located at least one of:
• within exhaust flow in the exhaust system,
• within exhaust flow in the exhaust pipe branch, and
• within exhaust flow in the exhaust gas to Diesel Exhaust Fluid heat exchanger;
• an outer cylinder having an outer cylinder upper cover and a lower cover,
• an inner cylinder having an inner cylinder upper cover, and sharing the lower cover with the outer cylinder, and
• the inner cylinder being concentric with the outer cylinder and extending beyond the top of the outer cylinder;
• and wherein
• the exhaust pipe branch includes an exhaust gas inlet pipe that directs exhaust gas into an annular space between the inner cylinder and the outer cylinder at a first end of the outer cylinder;
• the exhaust pipe branch further includes an exhaust gas outlet pipe that directs exhaust gas out of the annular space between the inner cylinder and the outer cylinder at a second end of the outer cylinder;
• and
• Diesel Exhaust Fluid being admitted to the inside of the inner cylinder from the Diesel Exhaust Fluid tank by way of a Diesel Exhaust Fluid entrance.

A method of thawing Diesel Exhaust Fluid in a vehicle having an engine, an Engine Control Module connected to the engine and configured to control the engine, an exhaust system connected to the engine and having selective catalytic reduction device, and a Diesel Exhaust Fluid injection system connected to the exhaust system and having a Diesel Exhaust Fluid tank, comprising the steps of:

• connecting an exhaust pipe branch to the exhaust system;
• connecting a heat exchanging apparatus to the exhaust pipe branch;
• configuring the heat exchanging apparatus to exchange heat from exhaust gas within the exhaust pipe branch to the Diesel Exhaust Fluid in the Diesel Exhaust Fluid tank;
• providing an exhaust gas control valve in the exhaust pipe branch and connecting the exhaust gas control valve to the Engine Control Module;
• locating at least one exhaust temperature sensor in the exhaust system and/or in the exhaust pipe branch, and connecting the at least one exhaust temperature sensor to the Engine Control Module;
• locating at least one Diesel Exhaust Fluid temperature sensor within the Diesel Exhaust Fluid tank proximate to at least one component of the heat exchanging apparatus, and connecting the at least one Diesel Exhaust Fluid temperature sensor to the Engine Control Module;
• and
• controlling the exhaust gas control valve by way of the Engine Control Module as a function of a temperature of exhaust flow within the exhaust system and/or within the exhaust pipe branch, and as a function of state of thaw and/or temperature of the Diesel Exhaust Fluid in the Diesel Exhaust Fluid tank;
• controlling by way of the Engine Control Module a percentage of opening of the exhaust gas control valve in such a way as to provide sufficient exhaust flow to pass through a component of the heat exchanging apparatus to quickly and efficiently melt the Diesel Exhaust Fluid within the Diesel Exhaust Fluid tank without exceeding a decomposition temperature of the Diesel Exhaust Fluid at any point where the heat exchanging apparatus comes into contact with the Diesel Exhaust Fluid;
• the heat exchanging apparatus further comprising:
• an exhaust gas to Diesel Exhaust Fluid heat exchanger located at least partially within the Diesel Exhaust Fluid tank;
• the exhaust gas to Diesel Exhaust Fluid heat exchanger further comprises:
• an outer cylinder having an outer cylinder upper cover and a lower cover,
• an inner cylinder having an inner cylinder upper cover, and sharing the lower cover with the outer cylinder,
• the inner cylinder being concentric with the outer cylinder and extending beyond the top of the outer cylinder;
• wherein
• the exhaust pipe branch includes an exhaust gas inlet pipe that directs exhaust gas into an annular space between the inner cylinder and the outer cylinder at a first end of the outer cylinder;
• the exhaust pipe branch further includes an exhaust gas outlet pipe that directs exhaust gas out of the annular space between the inner cylinder and the outer cylinder at a second end of the outer cylinder;
• and
• Diesel Exhaust Fluid being admitted to the inside of the inner cylinder from the Diesel Exhaust Fluid tank by way of a Diesel Exhaust Fluid entrance.