Automotive exhaust aftertreatment system with flash-boil doser

An exhaust aftertreatment system comprising

• an exhaust conduit defining an exhaust passageway for receiving a flow of exhaust gases therein, and
• a first reducing agent mixer coupled fluidly with the exhaust conduit and configured to receive the exhaust gases and inject a reducing agent into the exhaust gases, the first reducing agent mixer including:
• a mixing can defining at least a portion of the exhaust passageway for receiving the exhaust gases therein, and
• a flash-boil doser mounted to the mixing can and configured to inject a reducing agent through an injection aperture formed in the mixing can, the flash-boil doser including (i) a doser body that defines a flash-boil chamber with at least one heater arranged in the flash-boil chamber to heat reducing agent and thereby increase a pressure within the flash-boil chamber, (ii) a doser inlet coupled to the doser body that defines an inlet passageway that opens into the flash-boil chamber to admit reducing agent from an associated reducing agent tank, and (iii) a doser outlet coupled to the doser body, that defines an outlet passageway that opens from the flash-boil chamber into the exhaust passageway of the mixing can, wherein the doser outlet includes a pressure-activated outlet valve that blocks or allows flow through the outlet passageway, the pressure-activated outlet valve configured to move from a normally-closed position to an open position when a predetermined pressure within the flash-boil chamber is reached to discharge the heated reducing agent from the flash-boil chamber through the outlet passageway and into the exhaust passageway for mixing with the exhaust gases therein during use of the reducing agent mixer in the over-the-road vehicle.

An over-the-road vehicle, the vehicle comprising

• an internal combustion engine configured to produce a flow of exhaust gases that are conducted through an exhaust passageway defined by an exhaust conduit, and
• an exhaust aftertreatment system comprising
• a reducing agent tank formed to include an internal region storing a reducing agent therein,
• a reducing agent pump configured to displace reducing agent from the reducing agent tank,
• a mixing can defining at least a portion of the exhaust passageway for receiving the exhaust gases therein,
• a flash-boil doser mounted to the mixing can and configured to inject a reducing agent through an injection aperture formed in the mixing can, the flash-boil doser including (i) a doser body that defines a flash-boil chamber with at least one heater arranged in the flash-boil chamber to heat reducing agent and thereby increase a pressure within the flash-boil chamber, (ii) a doser inlet coupled to the doser body that defines an inlet passageway that opens into the flash-boil chamber to admit reducing agent from an associated reducing agent tank, and (iii) a closer outlet coupled to the closer body that defines an outlet passageway that opens from the flash-boil chamber into the exhaust passageway of the mixing can, wherein the doser outlet includes a pressure-activated outlet valve that blocks or allows flow through the outlet passageway, the pressure-activated outlet valve configured to move from a normally-closed position to an open position when a predetermined pressure within the flash-boil chamber is reached to discharge the heated reducing agent from the flash-boil chamber through the outlet passageway and into the exhaust passageway for mixing with the exhaust gases therein during use of the reducing agent mixer in the over-the-road vehicle,
• a reducing agent sensor configured to detect a parameter associated with reducing agent within the exhaust aftertreatment system, and
• a heater control unit in communication with the reducing agent sensor and configured to manipulate operation of the heater of the flash-boil doser based on signals received from the reducing agent sensor.