Patent ID: 7399171

Claim:
A rotary pump for a braking device, comprising: a rotary portion that is equipped with an outer rotor having an inner toothed portion along an inner periphery thereof and an inner rotor having an outer toothed portion along an outer periphery thereof and making a rotational movement around a drive shaft, and that is mounted and constructed such that a plurality of interstitial portions are formed by meshing the inner toothed portion and the outer toothed portion with each other; and a casing that has a central hole into which the drive shaft is fitted, a suction port for sucking brake fluid into the rotary portion, and a discharge port for discharging the brake fluid from the rotary portion, and that covers the rotary portion, wherein while a first containment portion as one of the plurality of interstitial portions with a maximum volume and a second containment portion as one of the plurality of interstitial portions with a minimum volume serve to maintain a differential pressure between the suction port and the discharge port, the brake fluid is sucked from the suction port and discharged from the discharge port through a rotational movement of the rotary portion; the casing has a first side plate and a second side plate sandwiching the outer rotor and the inner rotor in an axial direction of the drive shaft; the first side plate is provided with sealing means for sealing spaces between axial end faces of the outer rotor and the inner rotor and an axial end face of the first side plate, on one side in the axial direction of the drive shaft in the rotary portion; the outer rotor and the inner rotor are pressed against the second side plate due to a discharge pressure of the brake fluid acting on the sealing means on the other side in the axial direction in the rotary portion, so that spaces between the axial end faces of the outer rotor and the inner rotor and an axial end face of the second side plate are mechanically sealed; the second side plate is provided with a discharge groove communicating with the discharge port and a suction groove communicating with the suction port in the mechanically sealed axial end face of the second side plate; the discharge groove and the suction groove include a circular-arc side facing the suction groove and a circular-arc side facing the discharge groove respectively; and the circular-arc side of the suction groove has a larger curvature than the circular-arc side of the discharge groove.