| 摘要 |
A fitting clearance of a relief valve functions as an air bleeding orifice. When a discharge pressure reaches a relief pressure so that the relief valve turns into a relief state, a spool is moved so as to limit flow-out of hydraulic oil through the fitting clearance. As a result, generation of air trapping is suppressed by air bleeding function of the relief valve in a closed state. Air in a discharge oil passage is discharged quickly in the initial period of the startup of an electric oil pump, thereby improving rise-up of discharge pressure. During normal pump operation in which the relief valve is held in a relief state, pressure loss due to flow out of the hydraulic oil from the fitting clearance is suppressed and consequently, an electric oil pump having substantially the same discharge performance as conventionally can be used. |
