Patent GB-973493-A (GB)
Title: Variable-speed transmission mechanisms
IPC: F16H61/02
Filed: 1961-02-22
Abstract: 973,493. Change speed gear and control. BORG-WARNER CORPORATION. Feb. 22, 1961 [March 4, 19601, No. 6572/61. Heading F2D. In a fluid pressure control system for an automobile change speed gear, to provide a main line pressure for gear establishing clutch and brake servomotors which is high for starting and heavy loads and low for high speed and light loads, a main regulator valve 101 is subjected, for pressure increasing, through a restriction 201 and a port 185, to a control pressure (hereinafter referred to as " TV " pressure) variable generally in accordance with engine load and provided, in a line 126, by a valve 103, controlled by inlet manifold depression (Fig. 5B, not shown) or, as shown, by accelerator pedal position, and, for pressure decreasing, through a port 192, to a further control, pressure provided by a valve 105 modulating TV pressure and subjected to the opposed forces of a pressure variable in accordance with vehicle speed (" governor " pressure) acting through a port 261 and of TV pressure so that at a certain relationship of governor and TV pressure it applies full TV pressure to the port 192 for regulation of the valve 101 thereafter directly by TV pressure. Function summary.-The gear provides two reduced forward ratios, direct drive, and reverse. Drive setting D1, of a manual selector valve 100, selects low speed followed automatically under the control of vehicle speed and engine load by intermediate speed and finally direct drive engagement. In drive setting D2, which may be omitted for low power engines, the vehicle starts in intermediate speed, low speed being omitted. Low setting L provides twoway low for hill braking. 3-2 shift is softened except during accelerator kickdown shift which is provided for 3-2 and 2-1 shifts. Gear arrangement.-A planetary gear 16 in series behind a torque converter 15 of the overrun reactor type comprises long planets 34 arranged on a carrier 36 and meshing a front sun 31, a ring 32, and, through short idler planets 35, a rear sun 30. The carrier 36 may be stationed one-way by a sprag-type one-way detent 21 or two-way by a friction brake 20. The ring 32 is directly connected to an output shaft 11 and has external teeth 71 engageable by a pawl (not shown) for park lock. The rear sun 30 may be friction clutched at 17 to the turbine shaft 12, and the front sun 31 may be friction clutched at 18 to the shaft 12 or friction braked at 19. In Low, the clutch 17 is engaged for drive through the short and long planets 35, 34, the carrier reacting on the one-way detent 21. In intermediate, the clutch 17 and the brake 19 are engaged, the sun 31 acting as the reaction member arid the one-way detent 21 releasing. In High, both clutches 17, 18 are engaged for solid 1/1 drive through the planetary gear. In Reverse the clutch 18 and the brake 20 are engaged for drive through the long planets 34. In two-way, hill-braking, Low, the clutch 17 and brake 20 are engaged. Friction clutches and brakes.-The clutches 17, 18 of the multi-disc friction type, are actuated respectively by a fluid-pressure servomotor 48 through a Belleville washer lever functioning as a return spring, and directly by a spring- returned servomotor 57, the piston of which has a fluid bleed port and a centrifugally actuated ball check valve preventing clutch actuation by centrifuged entrapped fluid. The brakes 19, 20 are of the servomotor actuated band brake type, the servomotor of the brake 19 having a release cavity. Fluid supply system.-Front and rear pumps 114, 115 supply a pressure main line 121 through one-way valves 111, 112, the rear pump taking over the supply on increase of output speed. Fluid system, components shown include the main regulator valve 101 exhausting to the converter; a converter regulator valve 102 exhausting to a lubrication line 124 and, on excessive pressure, to the front pump suction line; a converter check valve 113 inhibiting converter drainage; the manual selector valve 100 providing Park, Reverse, Neutral, D2 range (may be omitted), Dl range and Low; a kickdown shift valve 104 acted on by the accelerator pedal 243; the throttle valve 103 acted on by the accelerator pedal through the kickdown valve 104 and a spring 225; the modulator valve 105 providing modulated pressure in a line 127 less than or equal to TV pressure; a servo-orifice control valve 109 for softening 3-2 downshift; a D1-D2 control valve 110 which may be omitted; a 1-2 shift valve 107 responsive to spring, governor and main line differential pressures and to a " shift plug " pressure in a line 138 which pressure, regulated by a shift plug 333 in a 2-3 shift valve, is less than TV pressure by a predetermined amount; the 2-3 shift valve 108 responsive to spring, TV, governor, " shift plug " and main line differential pressures; and a governor valve, 106, Fig. 4, or Fig. 6, rotating with the output shaft 11 and providing pressure in a line 128 varying with output speed. Operation.-In drive D1 the selector valve connects the main line 121 through a line 130 to the 2-3 shift valve 108 where it is initially blocked; through a line 131, to the 1-2 shift valve 107 where also it is initially blocked; to the governor valve; and, for low speed engagement, to the servomotor 48 for the clutch 17. The D1-D2 valve 110 is positioned to connect governor pressure in the line 128 to the 1-2 shift valve 107. At a vehicle speed depending on throttle position the 1-2 shift valve 107 is moved to connect the line 131 to a line 137 to the servomotor of the brake 19 for intermediate speed engagement. To provide a 2-1 downshift speed lower than 1-2 upshift speed and rapid up and down shift, upshift of the shift valve 107 cuts off " shift plug " pressure and also removes a differential force imposed by main line pressure. When governor pressure predominates, the 2-3 shift valve is moved to connect the line 130 to a line 139 to the servomotor 57 of the clutch 18 and to the line 141 to the release cavity of the brake 19 through the servo orifice control valve 109 which is leftwardly moved by a combined force of TV and governor pressures. To provide a 3-2 downshift speed lower than 2-3 upshift, and rapid downshift, upshift of the 2-3 shift valve 108 cuts off the TV and " shift plug " pressures and also removes a differential force imposed by main line pressure. On 3-2 downshift the servomotor 57 and, through the valve 109, the release cavity of the brake 19 are drained through the 2-3 shift valve 108 and the manual selector valve 100. On 2-1 downshift the servomotor of the brake 19 is drained through the 1-2 shift valve and the manual selector valve 100. On 3-2 accelerator kickdown the valve 104 connects a downshifting, spring- augmenting, full TV pressure to the port 344 at the right of the 2-3 shift valve. On 2-1 accelerator kickdown the full TV pressure provided by the valve 104 is connected to the right of the 1-2 shift valve, and also, prior to downshift, to provide a lag between forced downshift and upshift, acts differentially on lands 316, 317 of this shift valve. The servo orifice control valve 109 acts by its restriction 140 to soften the engagement of the brake 19 in 3-2 downshift by slow drainage of the release cavity of the brake 19; however in 3-2 kickdown, TV pressure acting on the valve 109 at 368 permits by-passing of the restriction 140 and rapid drainage of the release cavity resulting in rapid engagement of the brake 19. Governor pressure acting at 365 on the valve 109 also permits rapid filling of the release cavity of the brake 19 for 2-3 shift where the throttle is suddenly released for upshift. In drive D2, the manual selector valve 100 directs main line pressure to the right of the D1-D2 control valve 110 which then moves to block governor pressure in line 128 and direct main line pressure through a line 135 to maintain the 1-2 shift valve in its upshifted position. In Low, the manual selector valve 100 directs main line pressure through a line 132 to the 1-2 shift valve to maintain the latter in its downshifted position and, through a line 136, to pressurize the servomotor for brake 20 engagement. If the vehicle is moving and the 1-2 shift valve is upshifted when the valve 100 is moved to " L," the 1-2 shift valve downshifts when governor pressure is overcome; however, once the 1-2 shift valve is downshifted no amount of governor pressure will effect an upshift. If the vehicle is moving and the 2-3 shift valve is upshifted when the valve 100 is moved to " L," the servomotor 57 for the clutch 19 and the release cavity of the brake 19 drain through the 2-3 shift valve and the valve 100 to effect a prompt 3-2 shift. In Reverse, the manual selector valve 100 directs main line pressure to the 1-2 shift valve to downshift the latter and pressurize the servomotor for brake 20 engagement, and, via the 2-3 shift valve, to the servomotor 57 for clutch 18 engagement. Main line pressure is also directed to the release cavity of the brake 19 via the 2-3 shift valve and the servo orifice control valve 109, and to the servomotor of the brake 19 via the 1-2 shift valve, to balance this servomotor and maintain it in disengaged condition. The servomotor 48 and the governor valve supply line 131 are drained through the valve 100. Governor valve.-The governor valve 106 in Fig. 4 comprises a radially bored casing 270 rotating with the output shaft 11 and having main line pressure, governor pressure and exhaust ports 277, 278 and 229, a sleeve 272 sliding in the radial bore and having different sized lands 280, 281, and a centrifugal weight 273 piloted in the sleeve 272 and acting thereon through a stem 274, cap 275 and a spring 276. Outward movement of the sleeve 272, acted on by the weight 273, admits main line pressure which then acts on the different lands 280, 281 to tend to move the sleeve inwardly thereby providing a governor pressure regulated as a function of output speed. The governor