Patent GB-552679-A (GB)
Title: Improvements in or relating to apparatus for the control of mechanism
IPC: F02D9/00
Filed: 1941-10-13
Abstract: 552,679. Fluid-pressure servomotor-control systems. NAPIER & SON, Ltd., D., HALFORD, F. B., and WALLACE, P. J. Oct. 13, 1941, No. 13143. [Class 135] The flow of pressure fluid to a mechanism is controlled by two co-operating valves, one of which is actuated by a power device controlled by a valve moved by a pressure sensitive capsule in an adjustable ported member while the other valve is moved at the same time as the ported member is moved to adjust the datum of the device. The Figures show the application of the apparatus to the control of a change speed gear in a supercharger drive. The change speed gear is indicated at T and is controlled hydraulically by a valve U movable between positions U<SP>1</SP>, U<SP>2</SP> by a double-acting piston O<SP>3</SP> working in a cylinder O. The supply and exhaust of pressure fluid to and from the cylinder is controlled by two concentric rotary cylindrical valves L, M mounted in a casing N. A port N<SP>2</SP> in the plane 3 - 3 and a port in the plane 4 - 4 is connected by a pipe P with one side of the piston while a second pair of ports in these planes is connected by a pipe P<SP>1</SP> with the other side of the piston. The inner valve M is divided by partitions M<SP>2</SP>, Q<SP>1</SP> into three chambers M3, M<SP>8</SP> and Q<SP>2</SP>, the chamber M<SP>3</SP> being an exhaust chamber, the chamber S a supply chamber and the chamber Q<SP>2</SP> a supply chamber for a second mechanism. In the plane 3 - 3 the inner valve has two ports and the outer valve a single port whereby the connection between an exhaust conduit through a hollow shaft M<SP>1</SP>a and the two ends of the cylinder is controlled. In the plane 4 - 4 the inner valve has two ports and the outer valve has a single port while in the plane 6 - 6 the inner valve has a single port M<SP>9</SP> co-operating with a supply port in the casing N whereby pressure can be supplied to the two sides of the piston. The outer valve is rotated by a power piston J<SP>1</SP> acting through skew-gears J<SP>3</SP>, K and K2, L<SP>1</SP> under the control of a piston valve C actuated by a pressure sensitive bellows A subject to barometric or boost pressure. The valve C works in a ported liner adjustable axially to vary the control point by a hand lever H<SP>2</SP> acting through toothed gears H and F<SP>1</SP> and nut F engaging a quick-pitched screw D<SP>5</SP>. The nut F is formed externally with a skew-gear F2 connected by skew-gears G, G2, Ml with the hollow shaft M<SP>1</SP>a whereby the inner valve is rotated at the same time as the ported sleeve is moved axially. When the piston J<SP>1</SP> has moved a predetermined distance the shaft J<SP>4</SP> engages a projection D<SP>6</SP> to move the ported sleeve and inner valve and give a follow-up action. The co-operating valves may be arranged to control the supply of pressure fluid to a number of points, the pressure sensitive capsule being subject to the pressure of the fluid supply so that in the event of the pressure falling the supplies to the less important points are interrupted.