Patent GB-1045340-A (GB)
Title: Improvements in hydraulic installations with multiple pressures
IPC: F15B1/027
Filed: 1963-08-21
Abstract: 1,045,340. Valves. SFERMA SOCIETE FRANCAIS D'ENTRETIEN ET DE REPARATION DE MATERIEL AERONAUTIQUE. Aug. 21, 1963 [Aug. 27, 1962], No. 33108/63. Heading F2V. [Also in Division F1] An hydraulic system comprises at least two accumulators 1, 2, calibrated to clearly different pressure and adapted to supply a utilization circuit 3 connected therebetween, and at least one other utilization circuit 3a branched between the high-pressure accumulator 1 and a reservoir 6, the high-pressure accumulator being charged by a pump 4 which delivers liquid from either the low-pressure accumulator 2 or from the reservoir 6. The charging of the accumulator 1 is controlled by a reverser distributer 11 and a distributer 12 and the lowpressure accumulator 2 is charged via the utilization circuit 3 from the accumulator 1. The reverser distributer 11 comprises a slide valve 13 slidable in a cylinder 14 fixed in a three-part body 15 having ports 16, 24, 31. The position of the slide valve 13 depends on the pressure of the accumulator 2 communicated through the port 16 to one side of the slide valve 13, the other end of which has a roller 21 engaging a cam lever 22 secured to a spindle 18 which constitutes a torsion bar return spring. The distributer 12 is similar in construction to the distributer 11 and has a slide valve 37 positioned in accordance with the pressure of the accumulator 1 supplied through a port 41. When the high-pressure accumulator 1 is fully charged the slide valve 37 is displaced to the right, as shown, and the pump supply is bypassed to the reservoir 6. The by-pass circuit comprises the supply pipe 34, a radial channel 65, longitudinal channel 56, and a radial channel 57 in the slide valve 37, a chamber 53 and a return pipe 61. If the high-pressure accumulator 1 requires recharging the slide valve 37 is automatically urged to the left by its torsion bar return spring 42, and provided the pressure of the accumulator 2 is sufficient to displace the slide valve 13 to the right, as shown, the pump 4 will draw from the accumulator 2 through ports 16, 24 in the distributer 11, pipe 48, an annular groove 52 in the slide valve 37 and pipe 58. The supply from the pump passes through the pipe 34, around an annular groove 66 in the slide valve 37 and into a port 67 communicating through a pipe 35 with the accumulator 1. If the pressure of the accumulator 2 is insufficient to displace the slide valve to the right the pump 4 draws from the reservoir 6 through a radial channel 27, a longitudinal passage 28, and a radial channel 29 in the slide valve 13 and a chamber 25 communicating with the reservoir 6 through a pipe 32. Supplementary accumulators 2a, 2b calibrated to the same minimum pressure as the low pressure accumulator 2 for supplying utilization circuit 71, 72 may be connected as shown. The supplementary accumulators 2a, 2b are charged from the high-pressure accumulator 1 through respective utilization circuits 3c, 3d and non-return valves 74, 75 prevent the accumulator from delivering one into the other. The embodiment according to Fig. 2 (not shown), describes a system having a highpressure accumulator and two or more accumulators calibrated to lower but differing pressures. A distributer 11 is associated with each low-pressure accumulator, but except for the distributer associated with the last accumulator, each has a solid slide valve 13 which serves merely to permit or interrupt the passage of liquid between the corresponding accumulator and the pump. In Fig. 3 (not shown), the system comprises two high-pressure accumulators 1, la, and a low-pressure accumulator 2 together supplying utilization circuits 3, 3a . . . 31. The accumulators 1, 1 are recharged from the pump 4 under the control of a distributer 92, the other elements of the circuit and the operation thereof being similar to Fig. 1. When the pressure in either of the accumulators 1, 1a falls, the slide valve 37 which is subjected to the total of the pressure prevailing in the accumulators 1 and 1a through ports 94, 101 moves to the left, thereby allowing the output from the pump 4 to enter the port 113 of the distributer 92. The distributer 92 comprises a sleeve 107 mounted for sliding on a fixed hub 108 and operated through the intermediary of a rocker lever 109 by two pistons 111, 112 subjected permanently to the pressures of the accumulators 1, 1a respectively. The output from the pump is therefore directed to whichever accumulator 1, 1a is the more discharged through ports 114 or 115 leading respectively to the accumulators 1, 1a