GB1379678A - Hydraulic coantrol systems of automatic transmission mechanisms - Google Patents

Abstract

1379678 Change-speed control REGIE NATIONALE DES USINES RENAULT and AUTOMOBILES PEUGEOT 21 June 1972 [21 July 1971] 29182/72 Heading F2D In a torque-converter-driven automatic transmission on a motor-vehicle, wherein two friction clutches E1 E2 and two brakes F1, F2, introducing ratios in a planetary gear, are engaged under control of a manual valve 33, a solenoid valve 34 and three valves 35 ... 37, not described, the servo pressure being regulated in accordance with engine speed and load, the speed parameter is derived from the pressure drop #p across a calibrated orifice 38, in conjunction with a throttling valve 42 and a main pressure regulator 26, in the following manner. An engine-driven volumetric pump 20 supplies a pressure p + #p through a line 21 to the inlet side 38e of the orifice 38, the outlet 38s of which supplies a pressure p to a line 39, 31, feeding the manual selector valve 33 and also the main pressure-regulator 26. Pressure p + #p, assisted by a spring 47, produces a leftward load on the spool 420 of the throttling valve 42, whilst pressure p produces a rightward load. A throttled outlet pressure p<SP>1</SP>, in a chamber 426 and line 32, loading the main regulator 26, is controlled by the throttling valve lands 421, 422 as follows. On starting, engine speed is low and hence also is #p, whereby the throttling- valve spool 420 is maintained in its rightward position, shown, in which the chamber 426 is exhausted through a restrictor 46, so that p<SP>1</SP> is zero, and the regulator valve 26 regulates p to a maximum. With increase in speed #p increases, causing leftward shift of the valve-spool 420, which gradually throttles the restricted exhaust 46, and finally, at a predetermined speed, opening the chamber 426 and line 32, fully to the passage 39, so that pressure p<SP>1</SP> becomes equal to p and pressure regulated by the main regulator valve 26 falls to a constant value for any particular engine load. The load factor is manifested by engine intake depression acting at 25 on a throttle valve 23 which applies a pressure pc to the main regulator valve 26. A three-dimensional pressure diagram is provided in Fig. 5 (not shown).