Torque control method and apparatus for an internal combustion engine in a series hybrid vehicle.

Abstract

A series hybrid vehicle according to the present invention comprises: a generator (1) directly connected to an internal combustion engine (2); a motor (4) for travel; and a battery (5). A target rotation speed (NGt) of the generator (1) and a target torque (TEt) of the internal combustion engine (2) are set according to a required electric power generation amount. When a rotation speed (NG) of the generator (1) is lower than the target rotation speed (NGt), a reduction correction for the torque (TE) of the internal combustion engine (2) is made. For example, a throttle valve opening degree is reduced. This suppresses an increase in regenerative torque in rotation speed control. Thus, it is not required to set the maximum permissible torque of the generator (1) to an excessively large torque and hence the size of the generator (1) can be reduced.

Claims

1. In a series hybrid vehicle, in which an internal combustion engine drives a generator and the vehicle is propelled by the output of an electric motor, The target rotational speed of the generator and the target torque of the internal combustion engine are set according to the required power generation amount. Compare the generator's rotation speed with the target rotation speed mentioned above. The generator's rotational speed is controlled by increasing or decreasing the generator's torque so that the generator's rotational speed conforms to the target rotational speed mentioned above. The internal combustion engine output torque is estimated by applying a correction for the lag factor in the torque change of the internal combustion engine to the target torque of the internal combustion engine, and the generator required torque is estimated as a value that balances this estimated internal combustion engine output torque. If the generator's rotational speed exceeds the target rotational speed, in parallel with the rotational speed control by increasing or decreasing the generator's torque, the generator's torque is compared with the estimated required torque for the generator, and the torque of the internal combustion engine is reduced according to the difference between the two. A method for controlling the torque of an internal combustion engine in a series hybrid vehicle.

5. The estimated torque required for the generator is calculated by considering the characteristics of the gear mechanism or damper mechanism interposed between the internal combustion engine and the generator. A method for controlling the torque of an internal combustion engine in a series hybrid vehicle according to claim 1.

6. The torque reduction of the internal combustion engine is corrected on the condition that the difference between the torque of the above-mentioned generator and the estimated required torque of the above-mentioned generator exceeds a predetermined threshold. A method for controlling the torque of an internal combustion engine in a series hybrid vehicle according to claim 1.

7. The magnitude of the gain in the torque reduction correction for the internal combustion engine is set to be larger as the difference between the torque of the generator and the estimated torque required by the generator increases. A method for controlling the torque of an internal combustion engine in a series hybrid vehicle according to claim 1.

8. The magnitude of the gain in the torque reduction correction for the output of the internal combustion engine is set to be greater the larger the increase in the difference between the torque of the generator and the estimated torque required by the generator per unit time. A method for controlling the torque of an internal combustion engine in a series hybrid vehicle according to claim 1.

9. In a series hybrid vehicle, in which an internal combustion engine drives a generator and the vehicle is propelled by the output of an electric motor, A target value setting unit sets the target rotational speed of the generator and the target torque of the internal combustion engine according to the required amount of power generation, A comparison unit that compares the rotational speed of the generator with the above target rotational speed, A rotational speed control unit controls the rotational speed by increasing or decreasing the torque of the generator so that the rotational speed of the generator conforms to the above target rotational speed, A generator torque estimation unit calculates an estimated internal combustion engine output torque by applying a correction for the torque change lag of the internal combustion engine to the target torque of the internal combustion engine, and calculates an estimated generator torque as a value that balances this estimated internal combustion engine output torque. When the generator's rotational speed exceeds the above-mentioned target rotational speed, in parallel with the rotational speed control by increasing or decreasing the generator's torque, a torque correction unit compares the generator's torque with the estimated required torque of the generator and corrects the torque of the internal combustion engine by reducing it according to the difference between the two. A torque control device for the internal combustion engine of a series hybrid vehicle.

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