| 摘要 |
<p>Filter for diesel fuel, particularly for feeding Diesel engines of motor vehicles, comprising a self-adjusting heater for the diesel fuel, arranged on the head of the filter, a filter cartridge (2) and a lower decantation chamber (10). The body of the filter comprises a cylindrical bowl (1) to which a cover (14) is welded on to which then a removable cover or head (25) is screwed, all made of thermoplastic material with an appropriate filler. The heater is a polymeric PTC resistor of a flat shape (35) with a circular crown, which extends over the entire free cross section of the filter head traversed by the diesel fuel. The heater is secured to the head by a cup-shaped supporting element (40), with holes for the passage of the diesel fuel into the bowl below. Current is supplied by a pair of conductors (52, 62) terminating with only two electric contacts one of which is located on one surface of the polymeric PTC resistor and the other on the supporting element (40) in direct contact with the opposed surface of the resistor. A thermoelectric switch (70) deenergizes the heater when the temperature of the entering diesel fuel exceeds a predetermined value. In operation the polymeric PTC resistor provides a greater amount of heat at the lower temperature according to an intrinsically self-adjusting behaviour.</p> |
