| 摘要 |
1,189,571. Change-speed control. CENTRE DE RECHERCHES DE PONT-A-MOUSSON. 26 Feb., 1968 [31 March, 1967], No. 9136/68. Heading F2D. An electrohydraulic automatic vehicle transmission includes an electrically-operated valve E v for locking an engaged gear ratio, the valve having two parallel control circuits, one of which includes a manual override switch X, while the other includes a downshift switch Y in series with a switch Z controlled by a cam 10 on the accelerator pedal H. Circuit details.-As shown for a four-speed gear a stepped plunger 6 controls II-III and III-IV shift switches through an hydraulic diaphragm servo V<SP>1</SP> connected by a pipeline 3 to an output driven member P producing a speed-proportional pressure. The valve E v is mounted in the line 3 and a second smaller servo V<SP>2</SP> in a branch line 9 controls the downshift switch Y. The shift switches are connected by leads 17, 20, 23 to solenoids E, F, G controlling distributers D for the shift actuators Q, R, S. A fuel control T and manual selector valve Sm are also provided. Operation.-As engine speed increases plunger 6 is raised by servo V<SP>1</SP> against a spring 7 to operate the shift switches and solenoids, of which latter F and G are energized for first gear, G for second, F for third, E for fourth, and E and F for reverse. Closing of the manual switch X causes valve E v to close to cut off servo V<SP>1</SP> from pressure supply member P, thus holding plunger 6 locked to maintain the engaged ratio. At a predetermined speed the pressure in lines 3, 9 operates servo V<SP>2</SP> to close switch Y, which has no effect so long as the accelerator pedal H is depressed sufficiently to maintain switch Z open, but if the pedal is raised to close switch Z the valve E v closes to hold the engaged ratio. With the pedal raised a reduction of speed causes reduced pressure in lines 3, 9 to open switch Y and valve E v , thus connecting servo V<SP>1</SP> to exhaust and moving plunger 6 to its lowest position, as shown, under which conditions solenoid G is effective to engage second gear. |
