Hybrid vehicle and method of braking by controlling an exhaust heat recovery device bypass valve on a hybrid vehicle

摘要

A method of braking a vehicle includes determining via a controller a desired braking power for braking the vehicle. Under the method, a bypass valve that controls exhaust gas flow through the exhaust heat recovery device is moved via the controller to a relatively restrictive position to provide at least some of the desired braking power.

主权项

1. A method of braking a hybrid vehicle that has a powertrain with an engine and that has an exhaust system including an exhaust heat recovery device, the method comprising:
determining via a controller a desired braking power for braking the vehicle; moving a bypass valve that controls exhaust gas flow through the exhaust heat recovery device to a relatively restrictive position to provide at least some of the desired braking power, compressed exhaust gas thereby causing increased torque on the engine to provide at least some of the desired braking power; wherein the exhaust heat recovery device has an inlet and an outlet, wherein the exhaust heat recovery device has a heat transfer passage and a bypass passage through which exhaust gas selectively flows between the inlet and the outlet; wherein the bypass valve has a first position that permits exhaust gas flow through the bypass passage and substantially prevents exhaust gas flow through the heat transfer passage; wherein the bypass valve has a second position that substantially prevents exhaust gas flow through the bypass passage and permits exhaust gas flow through the heat transfer passage; wherein the bypass valve has a third position that substantially prevents exhaust gas flow through both the bypass passage and the heat transfer passage; wherein said moving the bypass valve to the relatively restrictive position is moving the bypass valve from either the first position or the second position to the third position; and controlling the engine to at least one of open an engine throttle or raise engine speed, to thereby consume power when the desired braking power is greater than the charge power limit.