Drive unit

Electrical generator or motor structure – Dynamoelectric – Rotary

Patent

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Details

310113, 310114, H02K 7116

Patent

active

056775822

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a drive unit which is intended for the transmission drive of road vehicles. The electric drive unit includes two electric machines having casings which are flanged at their ends in axial alignment. Each electric machine includes an outside rotor with a wheel body arranged on the end where the two electric machines are flanged to each other. It also includes an inner annular stator provided with stator windings and stator laminations with an axial, substantially cylindrical recess, the stator being rigidly attached to the casing. Further, it includes a rotor shaft rigidly attached to the wheel body and extending into the axial recess in the stator, and a mounting, which is rotatable with respect to the housing, for the rotor shaft to which a coupling device for the output is connected.
In order to be able to compete technically with traditional drives based on internal combustion engines and conventional drive lines, such transmission drives must produce high powers with as compact a construction as possible. In this connection, it is frequently of particular importance for the drive to produce a high torque at low speeds of revolution (for instance, upon starting). A construction as outside-rotor machine satisfies this requirement very well.
2. Background of the Invention
From EP 0 249 807 B1, a drive arrangement of this type is known. It is developed as a tandem motor, i.e. it consists of two individual electric motors which have their casings flanged to each other at their ends with mirror symmetry. The electric motors are each developed as outside-rotor machines; they have permanent-magnet excitation and their diameter is several times greater than their axial length. Thus, at low speeds of revolution, a higher torque can be made available than could be supplied directly by the electric motor if this drive unit were provided with speed-reducing gears. The output shaft of in each case one electric motor is at the same time the input shaft of a transmission association with it. The two parts of the drive unit which are mirror images of each other are flanged to each other forming a block at the ends of the transmission. Spur-gear or toothed-belt transmissions are provided as transmission. As a result of the two transmissions, the axial length of the drive unit is practically doubled; furthermore, its height or its diameter is considerably increased.
This known solution results in a definite increase in the available torque and represents a relatively compact construction as compared with older solutions. Nevertheless, it is desirable further to decrease the structural size and, in particular, the axial length. This is particularly important since universal-joint shafts must be connected to the drive unit in order to transmit the drive power to the drive wheels. Due to the inward and outward movement of the drive wheels resulting from the suspension during travel, the axes of rotation of the universal-joint shafts shift continuously with respect to their position at rest (deflection angle). The greater this deflection angle, the greater the wear in the joints (for instance homokinetic joints) of the universal-joint shafts. With the same absolute inward/outward spring action, the deflection angle is smaller the longer the universal-joint shaft. It is therefore necessary to arrange the coupling device between the universal-joint shaft and the rotor of the electric machine as far as possible from the corresponding drive wheel. For a drive unit of this type, this means that the distance between the coupling device of the two electric machines which are flanged to each other should be as small as possible.
From EP 0 253 999 an electric drive developed as individual motor having a permanent-magnet outside rotor is known. The motor has no casing protecting it from the outside. Its stator is developed as an annular body and has a planetary gearing in the space surrounded by it. The shaft of the rotor is provided with the sun wh

REFERENCES:
patent: 4274023 (1981-06-01), Lamprey
patent: 5087230 (1992-02-01), Yates et al.
patent: 5166584 (1992-11-01), Fukino et al.

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