Dual catalytic converter exhaust-gas aftertreatment arrangement

An exhaust-gas aftertreatment arrangement for an internal combustion engine comprising:

• a first catalytic converter;
• a second catalytic converter arranged in parallel with the first catalytic converter, the first and second catalytic converters being arranged to receive exhaust gas from an engine;
• a connection pipe fluidly connecting an outlet of the second catalytic converter with an inlet of the first catalytic converter, thereby allowing a flow of exhaust gas through the connection pipe,
• wherein the inlet of the first catalytic converter comprises a constriction having a diameter which is smaller than a diameter of adjacent portions of the inlet, and wherein the connection pipe is connected to the inlet at the constriction,
• wherein the diameter of the constriction induces a lower pressure at the constriction in relation to a pressure in adjacent portions of the inlet of the first catalytic converter and in relation to an inlet of the connection pipe, which induces a pressure difference and causes exhaust gas to flow through the second catalytic converter and the connection pipe;
• a connection pipe valve configured to control a flow of exhaust gas through the connection pipe;
• and
• an outlet valve arranged in the outlet of the second catalytic converter and downstream of the location of the connection pipe, wherein the outlet valve is configured to control a flow of exhaust gas through the second catalytic converter.