Patent ID: 8887870

Claim:
A breather device of an automatic transmission that includes a case for accommodating a power transmission mechanism portion and oil, the breather device comprising: a main body that is separate from the case and is attached via an external upper part of the case, with the main body including a breather chamber that communicates air in the case with atmosphere outside the case and that includes an inner bottom surface; a first communicating portion provided at the main body and connected to an opening formed in the upper part of the case, the first communicating portion provides communication on an upper surface of the case between the air in the case and the breather chamber, and the first communicating portion and the opening are arranged such that the air in the case passes through the opening and then through the first communicating portion before reaching the breather chamber; a second communicating portion provided at the main body and at a position above the first communicating portion in a vertical direction and away from the first communicating portion in a horizontal direction, the second communicating portion provides communication between the breather chamber and the atmosphere; a downward gradient provided at the inner bottom surface of the breather chamber, the downward gradient guides the oil that has entered the breather chamber through the opening and the first communicating portion into the first communicating portion; and an energy dissipation chamber that reduces a flow force of fluid that has entered the breather chamber through the opening and the first communicating portion by changing a flow direction of the fluid, the energy dissipation chamber is provided in the breather chamber so as to face the first communicating portion, wherein an opposing surface of the energy dissipation chamber to the first communicating portion is opposed to the second communicating portion in the horizontal direction through the first communicating portion.