Patent GB-1123081-A (GB)
Title: Motor vehicle automatic change-speed transmission
IPC: F16H59/18
Filed: 1966-04-04
Abstract: 1,123,081. Change speed gear and control. FORD MOTOR CO. Ltd. 4 April, 1966 [10 May, 1965], No. 14784/66. Heading F2D. Relates to a fluid pressure control system for an automatic change speed epicyclic gear for motor vehicles wherein pressure in a main line 200, supplied by an engine driven pump 28 and determined by a Main Regulator valve 104, is supplied to ratio-establishing friction clutch and brake servomotors under the control 0 automatic (vehicle speed and engine load demand responsive) 1-2 and 2-3 shift valves 110, 112 and a Manual Control valve 128 having positions " R " (Reverse), " N " (Neutral) " D2 " (2-3 autoshift), " D1 " (1-2 and 2-3 autoshift) and " L " (Low, no auto upshifts when L selected whilst stationary). In such a system, if, e.g. in coasting, the Manual Control valve 128 is moved to " L " with the vehicle speed above a predetermined value, Int. (Intermediate) ratio (with prevention of upshift therefrom) is established until the vehicle speed reduces below said predetermined value when Low ratio (with prevention of upshift therefrom) is then established; and ratioestablishing servomotor pressure in the main line 200 is boosted during coasting, with closed throttle and torque direction reversed, to prevent friction clutch and brake slipping, only when the Manual Control valve 128 is in " L ", with the Int. ratio established, and above a predetermined vehicle speed, by a Coasting Boost valve 108 directing Intermediate Brake servomotor apply pressure to a Pressure Booster 106 acting on the Main Regulator valve 104. Gear arrangement.-An epicyclic gear in series behind a torque converter 10 of the overrun reactor type comprises two sun-ring trains having a common sun 66. First planets 68, on a first carrier 70 connected to an output shaft 72, mesh the sun 66 and a first ring 40, and second planets 78, on a second carrier 80, mesh the sun 66 and a second ring 76 also connected to the output shaft 72. Low ratio compounded reduced drive through both trains is by clutching at 38 the first ring 40 to the converter turbine shaft 36, the second carrier 80 reacting on a one-way detent 86 or, for Manual two-way Low, band braked at 84; Int. ratio reduced drive through the first train is by keeping the clutch 38 engaged and band braking at 52 the sun 66, the detent 86 releasing; solid 1/1 High is by keeping the clutch 38 engaged and additionally clutching at 50 the sun 66 to the turbine shaft, the brake 52 being released; and Reverse reduced drive through the second train is by clutching at 50 the sun 66 to the turbine shaft and band braking the second carrier 80 at 84. Friction clutches and brakes.-The Forward clutch 38 and the Reverse and Direct clutch 50 are actuated by fluid pressure servomotors 44, 62 respectively. The Int. band brake 52 is actuated by a fluid pressure servomotor 54 having apply and release chambers. The Manual Low and Reverse band brake is actuated by a fluid pressure servomotor 95. Fluid system components include.-The Main Regulator valve 104 exhausting to the converter through a line 170 provided with a relief valve 172, used in event of Main Regulator valve malfunction, and a valve 176 set to open at 5 p.s.i., preventing converter drainage, and exhausting to a low pressure lubrication system; a Primary Throttle valve 116 providing TV (actually inlet manifold pressure responsive) pressure in a line 266; a Throttle Booster 120 and a Throttle Modulator 396 respectively boosting, to a line 398, and modulating, to lines 328, 400, 402, TV pressure to provide more useful shift signal pressures; the Pressure Booster 106 acting on the Main Regulator valve and responsive to pressures in a line 164 pressurized in Reverse, pressures in a line 166 leading to the Coasting Boost valve 108, and TV pressure; a Governor valve 118 connected to the output shaft, having primary and secondary elements 92, 93, and providing a vehicle speed responsive Governor pressure in a line 248 in L, D1 and D2 Manual Control valve positions only above a predetermined vehicle speed; a Cut-Back control valve 270 subjected to opposing Governor and TV pressures to direct, during starting, TV pressure to the Coasting Boost valve 108 which normally directs such TV pressure to the Pressure Booster 106; the 1-2 and 2-3 shift valves 110, 112 responsive to opposed Governor and modulated TV pressures; 1-2 Shift Capacity Scheduling and Accumulator valves 122, 124 providing gradual energization of the Int. servomotor apply chamber; a 2-3 " Back-out " valve 144 cushioning engagement of the Reverse and Direct clutch 50 at low TV pressure; a 3-2 Coasting Control valve 126 determining the cushioning of engagement of the Int. brake 52, during coasting and following operation in High, in dependence on vehicle speed; a " Manual Low " valve element 426 acting on the " Backout " valve 114; and a Downshift valve 122 under the control of the vehicle operator. Operation.-In Drive D1, the Manual Control valve 128 directs main line pressure through a line 222 to the Forward clutch 38, and through lines 222, 316 and a line 224 to the 1-2, 2-3 shift valves 110, 112 where, as shown, it is initially blocked. Low ratio is thereby established. When Governor pressure predominates, the 1-2 shift valve 110 upshifts to direct main line pressure through a line 318, the 1-2 Shift Capacity Scheduling and Accumulator valves 122, 124, a line 364, the " Back-out " valve 114, and a line 366 to the Int. brake apply chamber for Int. ratio establishment. On this 1-2 shift, modulated TV pressure is disconnected from the 1-2 shift valve. In Drive D2, the Manual Control valve 128 also directs main line pressure through a line 226 to the 1-2 shift valve to upshift the latter for starting in Int. ratio. When, in Int. ratio, Governor pressure again predominates, the 2-3 shift valve 112 upshifts to direct main line pressure through lines 406, 412 to the Reverse and Direct clutch 50 and through the line 412, a flow restricting orifice 414, and a line 416 to the Int. brake release chamber. A differential area between lands 388, 390 of the 2-3 shift valve spool, pressurized only in the downshift position of this valve, prevents hunting. With sufficient TV pressure, the spool of the 2-3 " Back-out " valve 114 is positioned as shown; however, on 2-3 upshift with low TV pressure, pressure in the line 412 to the Reverse and Direct clutch 50 forces the " Back-out " valve spool downwardly and pressurizes, through the line 366, the apply chamber of the Int. brake, simultaneously with pressurization of the Int. brake release chamber, to cushion release of the Int. brake until carburettor throttle setting is advanced to increase TV pressure sufficiently to return the " Back-out " valve. With the " Manual Control " valve 128 in " L ", the Manual Low valve element 426 is upwardly moved by pressure in the line 428 connected to the line 220, to keep the " Back-out " valve in its position shown. 3-2 shift rate is determined by a flow restricting orifice 410 in an exhausted line 408. In " L " (Low), the Manual Control valve 128 directs main line pressure to the Forward clutch 38, through a line 220, a flow restricting orifice 322, the 1-2 shift valve 110 in its position shown, and a line 326, to the Low and Reverse brake 84, and to the bottom of the 1-2 shift valve to prevent upshifts. Coasting.-If the Manual Control valve is moved to " L ", with the throttle relaxed to produce a coasting condition, and the vehicle speed is above a predetermined value, the line 224 supplying the Reverse and Direct clutch 50 is exhausted, and pressure in the line 220, acting on a land 306 of the 1-2 shift valve spool, is insufficient to overcome Governor pressure to downshift the 1-2 shift valve, thereby Int. is established until vehicle speed reduces. To cushion Int. brake application during 3-2 shift when coasting at relatively low speeds, exhaust of fluid from the release chamber of the Int. brake is through the line 416, the orifice 414 and lines 412, 408; however, at higher speeds, Governor pressure shifts the 3-2 Coasting Control valve 126 rightwards to directly connect the lines 412, 416 and by-pass the orifice 414. With the Manual Control valve 128 in " L ", with the Int. ratio established, and above a predetermined vehicle speed, Governor pressure shifts the Coasting Boost valve 108 downwardly to direct Int. brake apply pressure to the Pressure Booster 106 acting on the Main Regulator valve 104 to increase servomotor pressure. With the Manual Control valve 128 in D1 or D2, pressure in a line 292 connected to the line 224 maintains the Coasting Boost valve in its position shown. Manual Downshift.-The downshift valve 122 is mechanically linked to the drivercontrolled carburettor throttle, so that when it is shifted rightwards it connects Boosted TV pressure to the Shift valves 112, 110 through lines 332, 330, for downshifting thereof.