GB547676A - Improvements in or relating to transmission drive, particularly two speed drive for superchargers - Google Patents

Abstract

547,676. Valves. UNITED AIRCRAFT CORPORATION. March 3, 1941, Nos. 2891 and 2892. Convention dates, Jan. 10, 1940 and Feb. 24, 1940. Class 135] [Also in Group XXIV] In a speed gear in which a member 28 is driven at different speeds by gears 252, 254, the latter are successively clutched to a driving shaft 250 after having been synchronized with the driving members of the clutches by means of a fluid coupling arranged between the member 28 and the shaft 250 in parallel with the gear drives the coupling being inoperative when the clutch is engaged. The member 28 may drive the supercharger of an internal-combustion and, as shown, surrounds the engine shaft 36. The latter drives the shaft 250 to which are splined clutch members 268, 270, and the impeller 282 of a fluid clutch of the Fottinger type. The gears 252, 254 have clutch facings 264, 266. The driven parts of the fluid coupling are fixed on to the gear 254. The clutches are actuated by admitting pressure fluid to chambers 274, 276, through pipes 94, 130, and pressure fluid can be admitted or drained from the hydraulic clutch through a pipe 160. A single valve controls the supply of fluid pressure through the pipes 94, 130, 160. In operation, to drive the member 28 at low speed the control valve first passes fluid to the coupling so that the latter drives the member 28. When the speed of the latter reaches the low speed value the valve automatically supplies fluid to the clutch chamber 274, and drains the fluid coupling. The drive then continues through the gear 252. For the higher speed drive the valve drains the chamber 274 and supplies fluid to the coupling. When the member 28 has reached the higher speed value the coupling is drained and the clutch of the gear 254 is engaged. If desired the gears 252, 254, and the fluid coupling may all be mounted on different shafts driven from the engine shaft 36. The valve for controlling the supply of fluid to the pipes 94, 130, 160 is shown in Fig. 6. The pipes lead to ports 190, 192, 194, 196, in a valve casing, and a port 224 in a slidable valve member 188 can register therewith in succession. The valve member 188 has a piston 184 which is slidable in a cylinder 182 and has non- return valves 222 and a restricted aperture 238. Within the bore of the valve 188 is an abutment 214 having apertures 220 and acted upon by a spring 216. The abutment 214 is linked to an operating lever 208. The valve has passages 240, 236, 202, 198 leading to a drain port 200. Normally the valve interior and the spaces on both sides of piston 184 are filled with pressure fluid supplied by pipe 218. To ensure that the fluid in the cylinder 182 is warm the cylinder 182 is connected to a drain passage 230 through a duct 226 and a temperature sensitive valve 234. In the position shown the pipes 94, 130, 160, are connected to the drain port 200 and the member 28 is thus stationary. If the lever 208 is set to low gear position the abutment 214 moves to the right and the spring 216 acts on the valve which slowly moves to the right against the damping action of the fluid in the cylinder 182, which slowly leaks out through the restriction 238. The port 224 first registers with port 194 and the fluid coupling is operated to drive the member 28. When the latter has reached its low speed value the valve 188 has moved into the position in which port 224 registers with port 190 and port 194 is connected to the drain. The clutch 264 of the gear wheel 252 is thus engaged and low speed drive is then obtained through the gears 252, 256. If the lever 208 is now set to high gear position the valve 188 continues its movement to the right so that the drive is first taken up by the fluid clutch to speed up the member 28 and then is transferred to the clutch 266 of the high speed gear 254, 258. In changing down, the piston 184 can move rapidly to the left owing to the action of the valves 222 the fluid clutch is thus not actuated, the load on the member 28 tending to slow down the speed to a synchronizing value.