摘要:
In order to modify the rate at which a friction element is engaged to effect a gear shift in a multi-forward speed automatic automotive transmission with respect to vehicle speed, an orifice valve is arranged to be responsive to a vehicle speed signal (e.g. governor pressure) in a manner to establish a second fluid path between (a) the friction element (e.g. clutch) and an accumulator associated therewith and (b) the valve (e.g. 3-4 shift valve) which supplys the actuating pressurized hydraulic fluid and therefore reduce the flow restriction between the shift valve and the friction element when the vehicle is speed is above a predetermined value.
摘要:
A hydraulic control system for a lock-up clutch (L) includes a vehicle speed cut valve (18) having a spool (22) movable responsive to a governor fluid pressure (24) between a lock-up position and a non lock-up position. A solenoid valve (44) is provided which is energized such as during coasting of the vehicle or during kickdown operation. When energized, the solenoid valve (44) applies a line fluid pressure (42) to the spool (22) against the governor fluid pressure (24) to forcibly move it to the non lock-up position so as to release the lock-up clutch (L).
摘要:
A shift valve (24) comprises a spool (224) having a downshift position for establishing a lower speed ratio and an upshift position for establishing a higher speed ratio, a plug (225), and a spring between the spool and plug. The spool has a pressure acting area (224d) which governor pressure acts on, while the plug has a pressure acting area (124a) which throttle pressure acts on. At low throttle pressures, the spool moves from the downshift position to the upshift position when a predetermined vehicle speed is attained. At higher throttle pressures, the spool moves between the downshift and upshift position depending upon the governor pressure. The shift valve has a port (124b) formed therein which admits a downshift position hold signal fluid pressure (i.e., line pressure) between the spool and plug so as to hold the spool to the downshift position thereof.
摘要:
Disclosed herein is a hydraulic control system wherein under the control of a servo release changeover valve 23, a line pressure is supplied to a servo release fluid chamber (S/R) for a brake (B2) via a first flow path (434-435-437-444) at a flow rate determined by an orifice (616) during 2-3 shifting, and via a second flow path (412-435-437-444) at a flow rate determined by an orifice (617).
摘要:
The stroking order of the band brake servo piston (130) and the accumulator piston (114) are reversed under high and low transmission loads, therefore reversing the pressure modifying effects provided by the same. This is achieved by selecting the various areas and springs which determined the resistance against which the piston must stroke under high and low load conditions (wherein the level of the line pressure changes), and the forces which drive the pistons against the resistances.
摘要:
A one-way valve is arranged with an accumulator in a manner wherein the discharging of the accumulator is restricted. During upshifting, the stroking of a band brake servo in a release direction is induced before the charging stroke of the accumulator and the appropriate timing of the engagement of a high clutch (H/C) and the disengagement of a band brake (B/B) is induced. During downshifting, the pressure which is prevailing in the conduiting interconnecting the two friction elements is allowed to drop rapidly during the initial stage of the shift due to the provision of the one-way orifice (110) and allows the torque transmission capacity of the clutch to quickly reduce while inducing the stroking of the band brake servo in an engaging direction before the discharge stroke of the accumulator.