GB625984A - Improved fluid operated valve gear for fluid pressure engines - Google Patents

Abstract

625,984. Fluid-pressure engine valves. SPEEDIE, A. D. Aug. 22, 1946, No. 25013. [Class 122(ii)] In a fluid-actuated valve gear working in conjunction with a horizontal directacting duplex reciprocating pumping engine, the fluid actuated distribution valve on each side of the engine is operated by means of pressure taken from the working cylinder on the opposite side of the engine, the said pressure being released from the cylinder when the piston therein passes beyond an auxiliary passage arranged at a point to allow pressure to pass from the cylinder and to act directly on the respective ends of the distribution valve. Fig. 12A is a diagram of the engine showing the pistons P, P<2> on their inward stroke, and valves V, V<1> in their inner position, the main working passages through the valves being omitted for clarity. At the time when piston P<2> is reaching the end of its stroke, piston P moves to uncover passage D allowing pressure fluid to flow from cylinder C via passage F in valve V, passage G, adjustable regulating valve H to inner end of valve V<1>, the outer end being connected via passage G' to exhaust cavity O (shown in broken lines) in valve V. Valve V<1> is therefore moved to its outer position thereby reversing the flow to cylinder C<2> and causing piston P<2> to start its outward stroke. Piston P<2> moves past the passage D<2> when piston P is at the inner end of its stroke and pressure fluid flows from cylinder C<2> via passage D<3>, passage F' in valve V<1>, passage G<3> and regulating valve H<3> to the inner end of valve V, the outer end being connected by passage G<2> to exhaust cavity D<1> in valve V<1> so that valve V is moved to its outer position in which it reverses the flow to cylinder C, the piston P then moving on its outer stroke until it moves beyond passage D<1> at the time when piston P<2> has reached the end of its outward stroke. Pressure fluid then passes from cylinder C via passages D<1>, F, and G<1> to move valve V<1> to its inner position, thereby starting piston P<2> on its inner stroke. When piston P is at its outer end position, piston P<2> passes beyond passage D' and pressure fluid from cylinder C' passes via passages D<3>, F<2>, and G<2> to move valve V to its inner position, thereby moving piston P on its outward stroke. Positions of pistons and valves will then be as in Fig. 12A, and a new cycle commences. The valves are in the form of a plain unstepped piston with all pressure passages arranged through the body thereof and grooved at each end to take packing rings. As shown in Fig. 1 the main working pressure passages B<2>, B<3>, have greater area at the top or inlet end than at the bottom or outlet end in order that a greater pressure may be exerted on the top half of the valve to ensure good bearing of the bottom half in the valve housing. A tapped hole Y, into which a spindle is screwed, is placed off centre to counteract any rotary motion of the valve.