Patent GB-1019889-A (GB)
Title: Change-speed transmission mechanism
IPC: F16H47/08
Filed: 1964-04-29
Abstract: 1,019,889. Change-speed control. BORG-WARNER CORPORATION. April 29, 1964 [May 7, 1963], No. 17854/64. Heading F2D. To prevent shock in a motor car changespeed gear when a manual ratio-range selector valve is moved from its neutral or reverse position to a drive position, two ratio-establishing servomotors are filled simultaneously at low pressure, one acting as an hydraulic accumulator until a higher pressure is applied to the other, to establish a low ratio. As shown, movement of a manual ratio-range selector valve 106 to its D1 position from neutral, the car being stationary, connects regulated main pressure 123 to pipes 129, 132. The pipe 129 is closed at a port 166, Fig. 2C (not shown), of a front clutch control valve 110, but open at a port 168 to two pipes 150, 151. Regulated main pressure in the pipe 150 passes through pipes 139, 131 to a 1-2 shift valve 114, and to an output-speed-responsive governor 111 and a front clutch ratio-establishing servo 40, respectively. Regulated main pressure in the pipe 151 also flows to the 1-2 shift valve 114, which it upshifts to its second ratio position, so that pressure in the pipe 129 passes through to a pipe 146 and thence to the cylinder space 51a of a double-acting servo 51, energized against the bias of a disengaging spring 52a to engage another ratio-establishing clutch. The servo cylinder space 51a now cuts temporarily as an hydraulic accumulator. The clutch control valve 110 remains in its initial position only until the two servos 40, 51 have been filled at low pressure. Then back pressure begins to build up in the pipe 150, and moves the piston 155 of the valve 110 leftwards against the bias of a spring 157, so that a land 160 shuts off main pressure 123 from a port 167 connected to the pipe 150. Pressure in the pipe 131 leading to the two clutch servos 40, 51 is now passed only through a restriction 130, for gradual clutch engagement. Continuing build-up of pressure in the pipe 150 forces the piston 155 of the clutch control valve 110 leftwards, by-passing the restriction 130, and applying full main regulated pressure through a port 166 to the pipe 150 and the front clutch servo 40, establishing the first ratio. At the same time, the valve 110 shuts off the pipe 151 from direct connection to main regulated pressure 123. Instead, the pipe 151 is connected to the output-speed responsive governor 111, which is shut while the car is stopped. Accordingly, operating pressure is no longer supplied to the 1-2 shift valve 114, which returns to its first ratio position, venting the rear clutch servo 51a to sump. If the manual ratio-range selector valve 106 is moved to its D2, rather than to its D1, position, a second ratio start is effected, regulated main pressure then being supplied to a pipe 152 and the 1-2 shift valve 114 held in its second ratio position. The clutch control valve 110 then functions in a manner similar to that described.  The control circuit for the gearing also includes the following features. Input and output driven pumps 101, 102 draw oil from a sump 103 and act through primary and secondary pressure-regulating valves 104, 105 to provide regulated main pressure 123. A torque converter 15, through which the controlled change-speed gear is driven, is filled from the primary valve 104, which is in part controlled by a throttle-pedal actuated downshift valve 107 and a throttle-modulated valve 109. The 1-2 shift valve 114, described above, and a 2- 3 shift valve 115, are both controlled by the output speed responsive governor 111 and the TV valve 107. Change-speed gear.-The control circuit is described as operating a change-speed gear in which an hydrodynamic torque converter 15, Fig. 2A (not shown), drives an input shaft 13, and energization of the servo 40 engages a front disc clutch 17 to drive a sun gear 30, meshing planet pinions 33 of intermeshing planet pinions 32, 33; a one-way detent 21 stations a planet carrier 34, so that a low-ratio drive is established through a ring gear 35 to an output shaft 12. Second ratio is established by simultaneous hydraulic engagement of a band brake 19 to station a reaction sun gear 31, the one-way detent 21 overrunning. Third ratio (direct drive) is established by disengaging the brake 19 and energizing the servo 51 to engage a rear clutch 18, simultaneously with the clutch 17. Reverse is established by engaging the rear clutch 18 to drive the sun gear 31, and by hydraulic engagement of a band brake 20 to station the carrier 34.