Device for rotatably driving a cooling fan of an electric rotating

Abstract

An arrangement for cooling an electric rotating machine such as an alternator of an automotive vehicle by means of a fan which is intermittently driven in accordance with the cooling requirements of the electric rotating machine. A heat source is associated with the electric rotating machine which is representative of the degree of heating of the rotating machine. The heat source may be the radiator of the rectifier diodes of the alternator. A heat sensitive means in the form of a spring of 'memory alloy' controls the coupling/uncoupling with respect to the shaft of the rotating machine of the fan which is mounted free for rotation coaxially of the shaft of the machine. The heat sensitive means is in heat exchange relation with the heat source. The spring, for example, operates a lever which activates a control rod passing through the hollow shaft to control the coupling or clutching of the fan with respect to the rotating shaft. The 'memory alloy' may be of a type which suddenly elongates in going past a certain temperature; or, alternatively, of a type which suddenly contracts in going past a certain temperature. The sudden elongation or, alternatively sudden contraction of the spring is utilized to cause a coupling of the fan with the shaft.