| 摘要 |
The clutch oil pressure (PC1) supplied to a hydraulic control apparatus (6) of an automatic transmission is detected. If it is detected that the clutch oil pressure (PC1) is less than or equal to a first threshold value PA when a first oil pump (7) cooperative with a drive power source is to stop, the second oil pump (8) driven. Therefore, after the oil pressure (for example, PY) remaining due to the first oil pump (7) has decreased, the second oil pump (8) is driven, and an oil pressure (Px) needed for the hydraulic control of friction engagement elements is maintained. If it is detected that the clutch oil pressure (PC1) is greater than or equal to a second threshold value (PB) when the first oil pump (7) is to be driven, the second oil pump (8) is stopped. Therefore, the second oil pump (8) is stopped when the oil pressure provided by the first oil pump (7) rises to such a level that the oil pressure (Px) can be secured. Thus, the load on the second oil pump (8) is reduced so as to allow a size reduction thereof. <IMAGE> |
