GB825547A - Turbine with variable admission - Google Patents

Abstract

825,547. Turbines. ARMSTRONG SIDDELEY MOTORS Ltd. March 4, 1957 [March 20, 1956], No. 8626/53. Class 110 (3). A turbine has two-position pivoted inlet nozzle vanes which are adapted to be rotated only in succession and, either singly or in groups directly, and with a continuous movement, from an operative position to a position in which they cut-off the supply of motive fluid to an arc of the turbine inlet. The inlet nozzle vanes 40 have, at their radially inner ends, ball-type pivots 40a working in bosses 41 in a stationary ring 35 and, at their outer ends pivot pins 42 fast with ball-type pivots 43 engaged between partspherical surfaces in flanges 45, 46. The pivot pins 42 carry arms 48 having followers 49 which coact with cam tracks 50, 51 formed in the inner periphery of a ring 52. At diametrically opposite positions, the cam tracks 50, 51 are connected by a transfer portion 53. The ring 52 has a flange 55 provided with gear teeth 56 engaged by two idler pinions 57 and a driving pinion 58 driven by an electric motor 63 through a gear train 64, 65. Rollers supported from the housing 30 engage the opposite side of the flange 55. These rollers are arranged in pairs to straddle the positions of meshing of the pinions 57, 58 with the ring. When the followers are engaged in the earn track 50, the vanes 40 are in the fully operative position shown in Fig. 5 and when in the cam track 51 in the fully closed position. The vanes are moved from one position to the other when the follower passes through the transfer portion 53. By rotation of the ring 52, some of the vanes on diametrically opposite sides of the turbine are moved to the closed position, the remainder being in the operative position. In a modification, the vanes are connected in groups to a single follower. Preferably, the position of the vane pivots are such that the vanes are substantially pressure balanced in all of their pivoted positions.