Driving force transmission apparatus

A driving force transmission apparatus, comprising:

• a first rotary member that is rotated by a driving source of a vehicle;
• a second rotary member that is arranged on a rotation axis of the first rotary member so as to be rotatable relative to the first rotary member;
• a clutch that is interposed between the second rotary member and the first rotary member, and that couples the first rotary member and the second rotary member to each other such that the first rotary member and the second rotary member are disengageable from each other;
• a pressing force application mechanism that includes a piston that applies pressing force to the clutch through movement due to supplied hydraulic fluid;
• and
• an apparatus case that has two spaces that are adjacent to each other via the piston of the pressing force application mechanism, wherein
• an oil inlet portion for introducing the hydraulic fluid from the oil supply-side space among the two spaces to the clutch-side space among the two spaces is formed,
• the apparatus case has an oil outlet portion for delivering the hydraulic fluid from the clutch-side space to an outside of the clutch-side space with an oil delivery capacity lower than an oil introducing capacity of the oil inlet portion, and
• a pressure regulation valve that brings the oil inlet portion into an open state upon reception of a hydraulic pressure higher than or equal to a predetermined pressure from the hydraulic oil is arranged at the oil inlet portion.