| 摘要 |
<p>A vehicle with an engine (20) and a cab (14) has an air conditioning compressor (46) which is engaged and disengaged by a clutch (42) so as to control the sensed temperature (Te) in the cab to a preset temperature (Td). The clutch is controlled by a microprocessor control unit (40) which, when the sensed temperature is out of range, engages or disengages the clutch, as required to bring the temperature back in range. An engine load sensor (18) is sampled periodically by the control unit and a historical series of say 100 values are stored to indicate at each sampling whether the load was or was not below a preset level. The corresponding states of the clutch (42) are also stored. The control unit (40) derives a mean engine loading factor from the stored load values and a mean compressor activity factor from the stored clutch state values. The two said factors are compared and, when the controlled temperature (Te) is within range, the clutch (42) is engaged or disengaged in accordance with the results of the comparison. A similar control technique is applied to an air compressor (28) determining the pressure (P) in a pressure accumulator (26), an engine fan clutch (52) determining the engine temperature (Tc) and a field coil switch (37) of an alternator (32) determining the battery voltage (V).</p> |
