| 摘要 |
PURPOSE: To reduce oil hammering and pressure drop by relaxing pressure change of a pressure control valve when a changeover valve communicating the delivery side with the suction side of an oil pump having a plurality of delivery openings is switched from interruption to communication. CONSTITUTION: An oil pump 2 is driven to rotate during engine operation to generate a predetermined secondary pressure Ps for uninterruptedly supplying oil to a secondary control valve 20 through a main port 3. With the secondary pressure Ps as the main pressure, a predetermined lubricating pressure Po is generated by a lubricating control valve 22 and a primary pressure Pp is generated by a primary control valve 24 in correspondence with transmission ratio i. At that time, a control unit 40 calculates, compares and determines the flow rate Qp of the main port and the total use flow rate Qs . When Qs is larger than Qp as in the case of acceleration during low speed running, a changeover control valve 12 interrupts the lubricating pressure Po and the oil from a sub- port 4 is interrupted by means of a changeover valve 10. The flow rate therefrom is smoothly increased with respect to the control valve 20 under the pressure reducing control by the control unit 40. |
