| 摘要 |
1,167,550. Change speed control. FORD MOTOR CO. 22 Dec., 1966 [5 June, 1966], No. 57414/66. Heading F2D. Relates to a fluid pressure control system for an automatic change-speed gear for motor vehicles, wherein pressure in a main line 106, supplied by an engine-driven pump 28 and determined by a Main Regulator valve 108, is supplied to ratio-establishing friction clutch and brake servomotors under the control of Automatic (vehicle speed (Governor)) and engine load/demand ((TV) responsive) 1-2 and 2-3 Shift valves and a Manual Control valve 148 having positions " R " (Reverse), " N " (Neutral), "D2" (2-3 autoshift), "D1" (1-2 and 2-3 autoshift) and " L " (Low, no auto upshift when " L " is selected whilst stationary). In such a system, when the Manual Control valve is in " D1 " or " D2 " position, the spool 390 of a Coasting Boost valve is held by main line pressure, directed through a line 180, in its upper position to direct TV pressure, from a Cut-Back valve 356, to a Pressure Booster 128 acting on the Main Regulator valve; and when the Manual Control valve is in " L " position, the line 180 is exhausted to allow the Coasting Boost valve spool to be moved by Vehicle speed responsive Governor pressure in a line 200 against main line pressure in a line 393, at high vehicle speeds, to direct main line pressure to the Pressure Booster. This prevents a reduction in main line pressure when the vehicle is coasting at high speed and the engine carburettor throttle is at its minimum so that the clutch and brake have adequate capacity for the coasting torque. The Coasting Boost valve also acts, when the Manual Control valve is moved to " L " position, to reduce undesirable 2-1 downshift tendencies, and consequent vehicle lurching, obtained by opening the throttle while the vehicle is travelling at a relatively high speed. In this respect, main line pressure is increased by increase in TV pressure due to throttle opening (the TV pressure acting on the Pressure Booster) and acts, through the Manual Valve in " L " position and a line 176, in a downshift direction on the 1-2 Shift valve. To offset this, the increase in main line pressure acts on the Coasting Boost valve spool 390 to reduce the main line pressure in the line 146 to the Pressure Booster. The control system is similar to that of Specification 1,123,081, with the exception of the Coasting Boost valve described above; the Forced Downshift valve, 372, which is mechanically linked with the throttle and which when shifted rightwards connects main line pressure in the line 180, from the Manual Control valve, to the 1-2 and 2-3 Shift valves for downshifting thereof; and the 1-2 Shift Capacity Scheduling and Accumulator valves which comprise a modifier valve 402 and a shift regulator valve 404 and provide gradual energization of the Intermediate Brake servo apply chamber modified by TV pressure acting on the valve 402. |
