| 主权项 |
1. A method of starting an engine when a starter motor of a hybrid electric vehicle has a failure, the method comprising:
identifying a request for starting the engine in a state where the starter motor has the failure; determining a torque or load of an engine clutch and a pressure of the engine clutch when the request for starting the engine is made in the state where the starter motor has the failure; setting a torque of a driving motor to a smaller torque between a driving motor demanding torque and a torque obtained by subtracting the torque of the engine clutch from a maximum torque of the driving motor; and starting the engine with the set torque of the driving motor while controlling the engine clutch, wherein the torque or load of the engine clutch Tclutch is calculated by Equations (1) and (2) below, (Jeng: engine rotational inertia, weng—tgt: engine target speed, Teng—friction: engine friction torque),
Jeng·{dot over (w)}eng—tgt=−Tclutch−Teng—friction (Equation 1)Tclutch=−Teng—friction−Jeng·{dot over (w)}eng—tgt (Equation 2), and the engine rotational inertia is a pre-recognized value, the engine target speed is a predetermined value, and the engine friction torque is obtained through a predetermined test, and wherein pressure (F) applied to the engine clutch is calculated by Equation (3) below,
Fclutch=Friction coefficient×Effective radius×The number of friction surfaces×Sign (Equation 3), and the friction coefficient, the effective radius, and the number of friction surfaces are values determined according to a design specification of the engine clutch, and the sign is positive (+) when delta RPM is equal to or greater than 0, and the sign is negative (−) when delta RPM is smaller than 0. |
