Patent GB-758875-A (GB)
Title: Hydraulic pressure producing device
IPC: F04C14/02
Filed: 1954-05-14
Abstract: 758,875. Rotary pumps. DENISON ENGINEERING CO. May 14, 1954 [June 22. 1953]. No. 14228/54. Class 110(2) [Also in Group XXIX] A vane type pump having a plurality of pumping sections of equal or different capacities is provided with valve means by which the output of one or more pumping sections can be recirculated through the pump or to the supply reservoir thereof. The pump 20 of Fig. 1 has oppositely disposed sets of pumping sections which are balanced; the pump being provided with high- and low-pressure discharge ports 27. 28 respectively and inlet ports 26. The combined output from the ports 27 is fed through a check valve 35 into a conduit 34 having a restriction orifice 37 and a relief valve 50 whilst the combined output from the ports 28 is fed to the conduit 34 through a second check valve 35. A valve 36 is disposed across the orifice 37 and is formed integral with the housing of the pump or separate therefrom. The valve comprises a spring-loaded spool 46 having ports 51, 52, 53 adapted to control communication between inlet ports 41, 42 and an outlet port 43 leading to a reservoir 32, the inlet ports 41, 42 communicating with the discharge ports 27, 28 of the pump respectively. In feeding the exhaust from the valve 36 to the reservoir the fluid may be cooled. If desired, some or all of the fluid flowing from the port 43 may be recirculated to the conduit 33 connected to the inlet ports 26 of the pump. The crosssectional area of the orifice may be adjustable. In a modification (Fig. 2, not shown). the pump is provided with two sets of balanced pumping sections, each of which comprises one inlet chamber and three outlet chambers of decreasing volumetric capacity; the outlet conduits of chambers of like capacity being interconnected. The three interconnected outlet chamber conduits discharge into a common outlet condun through check valves arranged as shown in said Figure; a by-pass conduit being arranged to feed part of the combined output to the vanes for loading purposes. A manually operated valve is provided to connect a tapping taken off each of the three interconnected outlet conduits to the reservoir either individually or in various desired combinations. Means may be provided to maintain the pressure loading of the vanes (see Fig. 2A, not shown). In a second modification (Fig. 3, not shown) embodying a pump as described with reference to Fig. 2, the output of the pump is recirculated to the reservoir through a fluid motor and the common outlet conduit is connected through a relief valve to a spring-loaded valve. The valve successively connects tappings taken off each of the three outlet conduits to the reservoir, the number of tappings communicating with the reservoir being progressively increased. In a third modification (see Fig. 4) the line leading from reservoir 64 is provided with a check valve 126 and the outlet ports of the pump are connected through check valves 74 with a line 73 as shown. The line 73 is provided with a combined variable orifice and reverse valve 128 for the motor 127. The motor is connected to the reservoir 64 through a line 145 and a check valve 146 in order to relieve any vacuum therein. A torque motor 147 may be provided to control the movement of a spool 142 which determines the speed and direction of operation of the motor 127. The valve 140 functions in the same manner as valve 36 described above. In a fourth modification, Fig. 5, one part of the total output of the pump is delivered through ports 168 and two parts through ports 170, 170A through conduits 178, 180, 181 respectively, the total output of the pump being fed to a conduit 183 controlled by a valve 182. The valve 182 is connected in the circuit as shown and comprises spools 184, 185 disposed in interconnected chambers 186, 187 respectively; the valve in the position shown being adapted to direct the entire volume to the point of use. The arrangement is such that as fluid flows through a variable orifice 198 a pressure differential is created on opposite sides of the spool 185 thereby by-passing a portion of the volume from one set of pump output ports, all of the volume from one set of pump output ports, all of the volume from another set of output ports, or all of the volume from the latter set of ports plus part of the fluid from the first set of outlet ports; the valve being set as shown in Figs. 6, 7, 8, 9 respectively (not shown).