Patent GB-790891-A (GB)
Title: Improvements in or relating to change-speed transmission
Inventor: HARRISON WILLIAM V
IPC: F16H61/02
Filed: 1956-04-03
Abstract: 790,891. Change-speed gear. BORGWARNER CORPORATION. April 3, 1956, No. 10200/56. Class 80 (2). Shifts between second and third ratios of a three-speed and reverse gear on a vehicle are controlled automatically in response to variation in the resultant vacuum 128 at two points, one, 130, in the inlet manifold 124 of the engine, the other, 129, at the venturi 125 of the carburetter, such resultant being more stable than manifold vacuum alone. Output speed and accelerator kickdown also control shift, and the vacuum control effects upshift only, being rendered ineffective for downshift. Control is electrohydraulic. Gear arrangement.-The torque-converterdriven intermeshed planet gear is the same as that in Specification 704,787, and provides two reduced ratios, direct-drive and reverse by two disc clutches 16, 17 and two band-brakes 18, 19, all engaged by fluid pressure provided by input and output driven pumps 92, 93. Emergency low ratio is by the clutch 16 driving a small sun 26, and brake 19 on the planet-carrier, the drive issuing to output 11 from a ring-gear 15. Second ratio is by the brake 18 holding a larger sun 31, with the small sun 26 driven through the clutch 16 as in low. Third ratio, direct-drive, is by engaging both clutches 16, 17 to lock up the train. Reverse is by driving the larger sun 31 through the clutch 17 and holding the planetcarrier by the brake 19. Control. Hydraulic.-The clutches and brakes are controlled by a valve-block including a fourposition manual valve 64 and a two-position automatic shift valve 63. In neutral setting shown, the manual valve 64 exhausts all clutch and brake lines and blanks a pressure source 91. Moved one step right for invariable emergency low, the manual valve 64 supplies pressure 91 through a valve-groove 69 and line 90 to the brake 19, and through the valve-groove 69, internal bore 76, valve-groove 71 and line 85 to the clutch 16. A further rightward step of the manual valve 64 introduces reverse, by maintaining pressure on the brake 19, exhausting the clutch 16 at 94 and pressurizing the clutch 17 through valve-groove 69, passage 98, groove 78 of the automatic valve 63 and a line 88. Moving the manual valve 64 one step left from neutral introduces " Drive '' giving initially second ratio by pressurizing the clutch 16 through the valve groove 69 and a passage 87, and the brake 18 through the valve groove 71, passage 99, a groove 79 of the automatic valve 63 and line 89. Energization of a solenoid 82 by the automatic electric control pulls the automatic valve 63 to the right, exhausting the brake 18 at 96 and pressurizing the clutch 17 through the manual valve-groove 71, passage 99 and automatic valve-groove 78, thus causing 2-3 upshift. Control. Electric.-Energization of the upshift solenoid 82 is through contacts 104 of a relay 100, connected to the battery through a fuse 109 and the engine ignition switch 105. The winding 113 of the relay, energization of which closes the contacts 104 for upshift, is in series with three switches, one, 101, closed by increase in resultant vacuum (above 2.5 in. mercury) in the manifold-carburetter line 128; a second, 102, opened by kickdown of the accelerator pedal 141; and a third, 103, closed above a predetermined vehicle speed (13 m.p.h.) by an output-driven centrifugal governor 134. Above that speed and within normal range of accelerator movement, a 2-3 upshift will occur automatically when the resultant vacuum 128 is high enough to close the switch 101. Once upshift has occurred the relay 100 also closes hold-on contacts 114 by passing the vacuum switch 101 so that the latter is ineffective for 3-2 downshift, which occurs only by reduced vehicle speed opening the governor switch 103 or accelerator kickdown opening the switch 102. Curves are included showing comparisons between manifold vacuum and the resultant vacuum 128 at different road speeds and throttle openings, and also showing the variation in resultant vacuum with vehicle speed for different constant throttle openings, resulting in 2-3 upshift at 40 m.p.h. at full throttle and 13-14 m.p.h. at near-closed throttle.