| 摘要 |
A description is given of a two-stage clutch which is intended, in particular, for the drive of a cooling fan for an internal combustion engine. The two-stage clutch is provided with two clutch units, which are connected in parallel, can be actuated alternately by electromagnetic means, each have a coil switched in a manner dependent on the cooling power required and one of which is designed as a friction clutch. The other clutch unit is a structurally integrated eddy current clutch, the associated coil of which is, however, switched on only if there is a requirement for cooling power corresponding to fan speeds which are clearly below the maximum fan speed, preferably below 60% of the maximum fan speed. By virtue of this configuration, the eddy current component can be kept small and the heat generated is small. Sensitive matching of the fan speed in the lower speed range is possible, however. Troublesome switching noises are largely eliminated.
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