A METHOD FOR BRAKING A VEHICLE

摘要

A method for braking a vehicle driving forward, in which the vehicle has a propulsion system including a combustion engine with an output shaft (2a), a gearbox (3) with an input shaft (3a), an electric machine (9) comprising a stator and a rotor, and a planetary gear comprising three components in the form of a sun gear (10), a ring gear (11) and a planet wheel carrier (12). The vehicle is driven with one of the components connected to an output shaft of the combustion engine rotating with a lower rotational speed than one of the components connected to the electric machine. When the vehicle is braked, the electric machine is controlled to apply a brake torque to the input shaft of the gearbox, making the rotational speed of the combustion engine increase.

主权项

1. A method for braking a vehicle that is driving forward, wherein the vehicle has a propulsion system comprising a combustion engine with and output shaft, a gearbox with an input shaft, an electric machine comprising a stator and a rotor, and a planetary gear comprising three components in the form of a sun gear, a ring gear and a planet wheel carrier;
the output shaft of the combustion engine is connected to a first of the components of the planetary gear so that rotation of the output shaft causes rotation of the first component, the input shaft of the gearbox is connected to a second of the components of the planetary gear so that rotation of the input shaft causes rotation of the second component, and the rotor of the electric machine is connected to a third of the components of the planetary gear so that rotation of the rotor causes rotation of the third component the propulsion system further comprising locking means movable between a locking position, in which two of the components are interlocked so that the three components rotate with the same rotational speed, and a releasing position, in which the components are allowed to rotate with different rotational speeds; the method being started when the vehicle is being driven forward with the locking means in the releasing position and the third component rotating with a higher rotational speed than the first component; the method comprising the following steps: a) controlling the electric machine to apply a brake torque requested to the input shaft of the gearbox exceeding the product of the torque needed for driving the combustion engine to rotate and the transmission ratio of the planetary gear, b) checking and comparing the rotations speeds of at least two of the sun gear, the ring gear and the planet wheel carrier; continuing step a) while repeatedly or continuously carrying out step b) until the comparing in step b) shows that the condition that the rotational speeds of two of the sun gear, the ring gear and the planet wheel carrier are substantially equal is met, c) moving the locking means to the locking position when the condition of the rotational speeds in step b) is substantially met.