Patent ID: 8882480

Claim:
An oil pump for an automatic transmission, the automatic transmission comprising: an oil an filled with a volume of oil to a predetermined oil level and coupled to a transmission case and a pump cover of the oil pump; where the oil pump comprises a suction port connected to a first suction passage, wherein the first suction passage is arranged in parallel with a second suction passage connected to an auxiliary pump, and the first and second suction passages branch from an upstream suction passage leading to an oil strainer submerged in the volume of oil; a discharge outlet connected to a first discharge passage; the pump cover formed with a discharge port, the discharge port connected to the discharge outlet; an air vent hole formed in the oil pump cover disposed downstream of the suction port and upstream of the discharge outlet; where the transmission case is coupled to a control valve body; and a communication passage connected to the air vent hole and comprising the control valve body which projects toward a bottom of the oil pan and a lower portion of the control valve body is located below the predetermined oil level in the oil pan so as to communicate the air vent hole with the volume of oil inside the oil pan, where the communication passage is formed to extend through an inside of the transmission case and the control valve body.