Patent ID: 8316640

Claim:
A drain structure of a torque converter in an automatic transmission, the automatic transmission including the torque converter, an oil pump formed by an oil pump body and an oil pump cover, a transmission case accommodating the oil pump and an automatic speed change mechanism, and an oil pan provided under the transmission case, wherein: oil sucked from the oil pan by the oil pump is supplied to the torque converter and circulates therein, and the oil is drained into the transmission case through a drain oil passage, and the drain oil passage passes through a gap between the torque converter and the oil pump, is guided to an upper part facing a fitting surface between the oil pump and the transmission case, and is further guided from the upper part to a part under the oil pump and opens above an oil level in the transmission case through a concave groove formed on the fitting surface between the oil pump and the transmission case, and drain oil from the drain oil passage is discharged toward the oil pan.