Patent GB-800327-A (GB)
Title: Improvements in or relating to change-speed transmissions
IPC: F16H47/08
Filed: 1955-10-13
Abstract: 800,327. Change-speed gear. BORGWARNER CORPORATION. Oct. 13, 1955 [Jan. 12, 1955], No. 29195/55. Class 80 (2). To provide gradual engagement of a fluidpressure engaged power-train-completing friction engaging device in a vehicle change-speed transmission, the pressure of the engaging source is regulated to a relatively low value (20 p.s.i.) in the neutral setting N of a manual selector valve 82, and is increased to a relatively high normal operating value (80 p.s.i.), under accumulator delay, by moving the selector valve 82 to its D, drive, setting, so that the engaging device first engages softly at the said low pressure which is subsequently increased gradually to the normal high pressure. The initial soft engaging pressure is sufficient only to prevent relative motion due to idle drag of an input torque-converter. Function summary.-The gear provides two reduced forward and one reverse ratio torqueconverter driven, and an all-mechanical directdrive high. Drive setting D of the PNDLR manual selector valve 82 selects a one-way second speed start with light initial engagement. Subsequent shift to high is by a shift-valve 83 controlled manually or by unspecified automatic means to engage a direct-drive disc clutch 20 in opposition to pressure in the torque-converter casing, which pressure is at the same time reduced. Pressure in the servo system, but not in the torque converter, is doubled in reverse. Restrictors 151, 145 in the manual valve drains, retard release of low and reverse ratios, but their engagement is unrestricted so that in shuttling between L and R, the new ratio engages before release of the old, to avoid bump. Outputdriven pump pressure inhibits engagement of reverse during forward motion. Gear arrangement.-The gear comprises two sun-ring trains 15, 16 in series behind a torqueconverter 14 of the overrun reactor type driven by an input shaft 10. In first speed, two-way low-low, a band-brake 18 holds a front sun 30 and also, through a one-way clutch 40, holds against forward rotation, a rear sun 34 which is also held against reverse rotation through an opposed one-way clutch 39 by a second bandbrake 17. The torque-converter 14 drives the front ring 29, and the front planet carrier drives the rear ring 33, the rear carrier driving a final output shaft 11, both trains reducing. For second speed, one-way direct-low, the front train 15 is locked by a disc clutch 21 and the brake 17 alone remains engaged to hold the rear sun. High speed is by engaging the mechanical drive disc clutch 20 directly connecting input and output shafts. The front train lock-up clutch 21 remains ineffectively on, as does the rear brake 17 which is overrun. Reverse, oneway negative low-low, is by applying a bandbrake 19 to the front carrier and connected rear ring 33, whereby the front sun 30 drives the rear sun 34 reversely through the one-way clutch 40, and the rear carrier, reacting on the stationary ring 33, drives the output 11 at reduced speed. Fluid supply system.-Input and output driven pumps 80, 81 supply a system main 127 through one-way valves 128, 131, which close to that pump producing the lower pressure. System pressure increases slightly at output pump take-over. Fluid system components-include a main pressure regulator 84; PNDLR selector valve 82; manual or automatic 2-3,3-2 shift-valve 83; reverse inhibitor valve 85 blocking reverse pressure during forward drive; accumulator 86 for gradual pressure increase; converter shuttle and converter regulator valves 87, 88, for controlling converter pressure. Operation.-In neutral and park settings N, P, the selector valve 82 blanks the pressure main 127, in which pressure is regulated to 20 p.s.i. by a land 106 of a spring-loaded lower piston of the main regulator 84. The pressure main feeds the torque-converter 14 through the converter shuttle-valve 87 which, positioned as shown, provides two parallel paths, one restricted at 199, the other, 205, relatively unrestricted. A torque-converter exit line 222 bleeds to a lubricating port 234 variably controlled by the reduced end of a spring-loaded piston of the converter regulator valve 88. These valves 87, 88 together regulate idling converter pressure to 15 p.s.i. In drive D the selector valve 82 opens the pressure main 127 to lines 221, 155, 187. The line 187 engages the front train clutch 21 through the shift-valve 83 (in its lower, downshift, position shown) and a, line 188. The line 155 directly engages the rear brake 17. Initial engagement occurs at the light 20 p.s.i. pressure, which is sufficient to prevent the relative rotation due to idle drag of the torque-converter. Pressure in the line 221 acts leftwards on the piston of the accumulator 86, eventually overcoming its loading spring, and passing through a line 220 to act downwards on an upper piston 100 of the main regulator valve 84, which thereupon moves downwards until arrested at a smaller diameter bore 103 of the valve. The increased loading of the regulator spring 117 thereby produced increases pressure in the system main 127 to a normal operating value of 80 p.s.i., and in the torque-converter to 55 p.s.i. 2-3 Upshift.-When the shift valve 83 is moved manually or by unspecified automatic means to its upper, upshift position, line pressure 187 passes additionally into a line 189 which engages the direct-drive clutch 20 by acting on the left face of a piston 58, and at the same time reduces pressure in the torqueconverter casing acting in opposition on the right face of the clutch piston 58, by acting leftwards at 223 to open fully the relief opening 234 of the converter regulator valve 88, and also acting at 203 to shift leftwards twin pistons of the converter shuttle-valve 87, closing the converter feed-path 205 and leaving only the restricted parallel feed path 199. This reduces converter pressure to 30 p.s.i. in direct drive. Downshift action is simply reverse of upshift. Low range.-In L setting, the selector valve 82 pressurizes the accumulator line 221, and rear brake line 155, and also connects the latter to a line 156 engaging the brake 18. The accumulator 86 causes pressure build-up as in D setting.  Reverse.-In R setting, the selector valve 82 pressurizes the accumulator line 221, and a line 154 which latter feeds a front brake apply line 172 through the reverse inhibitor valve 85, providing the latter has not been depressed by output pump pressure 121, 171. Reverse brake pressure 154 also passes through ports 124, 116 to act downwards on an inner piston 113 of the main regulator valve 84, increasing its loading to double the line pressure 127 to 170 p.s.i. To prevent similar pressure increase in the torque converter, the reverse brake pressure 154 acts on the left piston of the converter shuttle-valve 87 to close the converter supply passage 205, leaving only the parallel restricted passage 199 (as for direct-drive) which causes converter pressure to maintain its normal 55 p.s.i. Low-reverse shuttle.-In shifts between Land R settings, the selector valve 82 exhausts the low and reverse brakes through restrictors 151, 145 respectively, so that release of each is delayed until after engagement of the other. This avoids a free period which might produce a, bump on reversal.