Patent GB-914016-A (GB)
Title: Improvements in or relating to epicyclic gear transmissions
IPC: F16D67/00
Filed: 1960-04-05
Abstract: 914,016. Hydro-mechanical variable-speed gear; change-speed control. SIMPSON, H. W., and FORSTER, L. M. April 5, 1960 [April 6, 1959], No. 12040/60. Class 80 (2). In a combined fluid coupling and planet gear in a vehicle, carriers 42, 48 respectively of sunring planet trains A, B (which may be identical, or have different-sized suns) are connected to an output shaft 60, sun 68 of train A is connected to ring 49 of train B, sun 53 of train B is connected to the coupling turbine 13, and the coupling impeller 12 is connected to an input shaft 10, there being provided fluid coupling filling and emptying means, a fluid-operated friction clutch C between the input shaft 10 and ring 40 of train A, and fluid-operated friction band brakes 36, 57 for the rings 40, 49. Control may be automatic for forward gears (Fig. 6) or manual (Fig. 7, not shown). In operation, in Neutral the coupling is filled while brakes 36, 57 and clutch C are released. In Low, brake 57 is engaged for drive through the coupling and train B. In 2nd the clutch C is engaged and the coupling emptied for allmechanical drive through train A, the turbine 13 being overdriven. In 1/1 Top, the coupling is re-filled and brake 57 released for split-torque drive through both trains A, B with fractional regenerative torque transmission through the coupling. In Reverse the coupling is filled and the brake 36 engaged, while clutch C and brake 57 are released, for drive through the coupling and both trains A, B. Peripheral exhaust valve 28 in the fluid coupling are held closed, against spring and centrifugal pressure, by fluid pressure in a line 66. For smooth 1-2 upshift to avoid resistance drag in the coupling as the turbine is accelerated to overdriven condition the coupling is arranged to be rapidly emptied at the moment the clutch C has absorbed substantially full torque by releasing line 66 pressure through a port 62 when a port closure washer 63 is relieved of direct (Fig. 1A, not shown) or indirect, as shown, axial thrust from the helically-toothed sun 53. Prompt release of brake 57 when backward torque reaction has substantially disappeared, during 2-3 upshift, is obtained by use of a self-energizing double-wrap brake band which, as actuating pressure is reduced, behaves as a one-way brake, giving self-timed release. A parking lock gear 47 is fixed to the carrier 42. Control.-The automatic fluid control system (Fig. 6) includes an input driven pump 18, a spring-loaded manual valve 70, a spring-loaded 1-2 shift valve 72, a spring-loaded 2-3 shift valve 71, a spring-loaded manual shift limiting valve 73, and servos 31, 36a, 57a, respectively for the clutch C and brakes 36, 57. When a manual lever 75 is in Neutral shown, pressure regulated by a spring-loaded valve 76 closes valves 28 through lines 77, 78, 66 and fills the coupling through a reducing valve 30. When the lever 75 is moved to DR, pressure is admitted to servo 57a through lines 77, 81. Beyond the valve 76 a spring-loaded ball valve 87 and a tapered valve 88 responsive to the position of the accelerator pedal 89 provide a pressure in lines 83, 84 which increases in engine speed and decreases with throttle opening. When pressure in lines 83, 84 increases sufficiently the valve 72 is fully shifted for 1-2 shift; the servo 31 is energized and line 66 is connected with an exhaust port 62 so that diminution of sun 53 torque will permit coupling exhaust through valves 28. When pressure in lines 83, 84, 90 increases further still, the 2-3 shift valve 71 (the spring of which has a higher preload than that of the 1-2 valve 72) is fully shifted for 2-3 shift, the servo 57a is deenergized and pressure in the line 77 is reapplied to close valves 28 and re-fill the coupling through the 2-3 shift valve 71, a line 91, 1-2 shift valve 72 and line 66. When the lever 75 is moved to " 2nd " or " 1st " the shift limiting valve 73 respectively blocks pressure to the shift valves 71, 72 and thereby respectively limits shifts to 2nd and Low. When the lever 75 is moved to R, pressure is admitted to the servo 36a, the coupling is filled, and a valve not shown blocks the line 83 to prevent operation of the shift valves 71, 72. The manual fluid control system (Fig. 7, not shown) comprises a five-position, manuallyoperated, linear-moving, ported distributer valve fed from the pump 18.