REAL-TIME MONITORING OF AUTOMATIC TRANSMISSION FLUID CONDITION

摘要

A tubular probe having annularly spaced electrodes is immersed in ATF and sequentially excited with an alternating voltage at a relatively high and lo w frequency. The current is measured at both frequencies and the difference in impedance computed; and, the differential impedance is corrected for temperature and the corresponding value of one of TAN per ASTM D-669, Delta Oxidation per ASTME-168 (.DELTA.OX) and HPDSC induction time per ASTM D-5483 (MIN) determined from a lookup table of values of TAN, .DELTA.OX and MIN versus impedance differential for known fluid conditions. The remaining usef ul life (RUL) may then be computed from determined present value of TAN, .DELTA.OX or MIN. When the temperature corrected impedance difference .DELTA.ZTC reaches 6.5 x 105 Ohms, the ATF is considered to have reached the end of its useful life.