Vorrichtung zum Verhindern eines übermäßigen Öltemperaturanstiegs für einen Drehmomentwandler eines automatischen Getriebes für ein mit einem Drehmomentwandler ausgerüstetes Fahrzeug

摘要

An excessive oil temperature increase prevention device for a torque converter of an automatic transmission is provided wherein, if the per-unit-time heating value of the torque converter becomes greater than or equal to an upper limit value, then the automatic transmission is downshifted and an upshift is inhibited. An expected input shaft speed and an expected input torque after the upshift are calculated. An expected speed ratio and an expected capacity coefficient are also calculated. A per-unit-time expected heating value after the upshift is calculated using the expected input shaft speed, the expected speed ratio, and the expected capacity coefficient. When the per-unit-time expected heating value becomes less than or equal to a lower limit value, the inhibition of the upshift is cancelled.