GB1250606A - - Google Patents

Abstract

1,250,606. Fluid-pressure servomotor systems. NATIONAL RESEARCH DEVELOPMENT CORP. Nov. 14, 1968 [Nov. 15, 1967], No.52095/67. Heading G3P. [Also in Division F1] A hydraulic servomotor has a valve disc 46 Figs. 1 and 7 rotatable by a stepping motor 26 and provided with sixteen circumferentially spaced passages 57 the outer ends of which co-operate with two similar but staggered rings of passages 56 in a flange 47 of output shaft 33 and an endplate 42 rotatable with shaft 33. Passages 56 cooperate with rings of passages 50 in housing parts 2, 4, there being eight passages 50 in each ring which connect alternately with a supply manifold 6 or 8 and an exhaust manifold 7 or 9; each passage 50 ends in an arcuate port 50<SP>1</SP> Fig. 7. An extension 38 of flange 47 houses ball pistons 41 which can react against a cam track 16 to cause rotation of shaft 33. In operation, displacement of disc 46 relative to shaft 33 causes the cylinders 39 housing ball pistons 41 to be supplied or exhausted in a predetermined sequence, and thereby causes like rotation of shafts 33 through an angle equal to that turned through by the disc - at which point all the cylinders 39 are disconnected from supply and exhaust and shaft 33 stops. The maximum angle through which disc 46 can rotate relative to shaft 33 is defined mechanically or in the control circuit of motor 26. In the embodiment of Figs. 10 and 11, the input shaft 83 is connected to a cylindrical valve member 95 having an annular enlargement 96 which connects supply and exhaust manifolds 126, 125 in housing part 76 with a ring of nine cylinders 89 having ball pistons 90 co-operable with cam track 79 to rotate output shaft 88. The valve member rotates on a sleeve 75 having rings of passages leading from the manifolds. The inherent imbalance of the output shaft is compensated by providing a hydrostatic thrust bearing 161. Further hydrostatic bearings are provided at 164 and 167. The motors can be used to position lathe turrets and ships rudders, and can be so constructed as to be linear acting. The input can alternatively be mechanical, hydraulic, pneumatic or manual, and the cam track could be generated on a radial plane such that the pistons move axially of the motor. (For Figures see next page)