| 摘要 |
PURPOSE:To smoothly perform the engine operation in a low-rotation region such as at the time of starting an engine at a low temperature by prohibiting the hydraulic control by a low-temperature hydraulic control device when the engine rotating speed is in the low-rotation region of the preset rotating speed or below. CONSTITUTION:When the operating liquid of the friction element (a) of an automatic transmission is at the fixed temperature or below, a low-temperature hydraulic control means (b) sets the operating liquid pressure to the maximum pressure. When the detecting means (c) of this hydraulic control device detects that an engine is in a low-rotation region of the preset rotating speed or below, the hydraulic control by the low-temperature hydraulic control means (b) is prohibited by a prohibiting means (d), and the operating liquid pressure is set to a low pressure in response to the ordinary engine load. The viscous resistance of the operating liquid with high viscosity in the low-temperature state is decreased to the utmost by the low pressure, and the load applied to the engine is decreased that much. The engine operation in the low-rotation region such as at the time of starting the engine can be smoothly performed. |
