Engine control device and method of hybrid vehicle

1. A method for controlling an engine depending on an engine load of a hybrid vehicle, comprising:

learning a change amount of an engine load by a learning unit;

determining by a torque determining unit at least one engine torque depending on a magnitude of the engine load;

calculating by a control unit an optimum torque value by using the learned change amount of the engine load and at least one determined engine torque; and

controlling the engine by using the calculated optimum torque value,

wherein the learning of the change amount of the engine load includes learning a deviation of a friction torque in an idle state, and

wherein the determining of the at least one engine torque comprises:

determining a first engine torque when the engine load is a minimum; and

determining a second engine torque when the engine load is a maximum.

2. The method of claim 1 , wherein the calculating of the optimum torque value includes calculating the optimum torque value by using the deviation of the friction torque, a predetermined maximum value of the friction torque deviation, the first engine torque, and the second engine torque.

3. The method of claim 2 , wherein the controlling the engine comprises:

measuring the engine load; and

summing the measured engine load and the calculated optimum torque value while the hybrid vehicle is driven to calculate an output torque of the engine and to control the engine by the calculated output torque.

4. An engine control device of a hybrid vehicle, comprising:

a learning unit configured to learn a change amount of an engine load;

a torque determining unit configured to determine at least one engine torque depending on a magnitude of the engine load; and

a control unit configured to calculate an optimum torque value by using the learned change amount of the engine load and the at least one determined engine torque and control an output torque of the engine by using the magnitude of the engine load and the optimum torque value while the hybrid vehicle is driven,

wherein the control unit comprises:

an optimum torque calculation unit configured to calculate the optimum torque value of the engine by using the learned change amount of the engine load and the at least one determined engine torque; and

an output torque calculation unit configured to calculate the output torque of the engine by summing the engine load and the calculated optimum torque value,

wherein the learning unit is configured to learn a deviation of a friction torque in an idle state, and

wherein the torque determining unit comprises:

a first torque determining unit configured to determine a first engine torque when the engine load is a minimum; and

a second torque determining unit configured to determine a second engine torque when the engine load is a maximum.

5. The engine control device of claim 4 , wherein the optimum torque calculation unit is configured to calculate the optimum torque value by using the deviation of the friction torque, a predetermined maximum value of the friction torque deviation, the first engine torque, and the second engine torque.