| 摘要 |
<p>A control system for an automatic transmission which includes one or more hydraulically actuated friction engaging mechanisms (7, 9, 10). An electrical control device (30) receives electrical signals representing engine load and vehicle speed from sensors (31,32) for these quantities, decides which speed stage of the transmission should currently be engaged, and selectively supplies actuating electrical energy to one or more hydraulic fluid pressure switching valves (23,24,25). These valves selectively provide supply of line pressure from a line pressure generator (18) to the hydraulically actuated friction engaging mechanisms so as selectively to engage the desired speed stage of the transmission. This line pressure generator which produces the line pressure is controlled according to the current value of a certain parameter representative of engine load. The value of the line pressure generated by this line pressure generator varies in response to the current value of this parameter representative of engine load. Accordingly the value of line pressure can be adjusted according to engine load so as to be most appropriate for engaging each one of the friction engaging mechanisms from its disengaged condition when so required, the line pressure being thus varied in response to engine load which determines the torque which the friction engaging mechanisms will each be required to transmit when engaged. Thus both jerky engagement and also slippage during the process of engagement of the friction engaging mechanisms can be prevented, and such smooth engagement of the friction engaging mechanisms ensures long life for the transmission.</p> |
