Patent GB-1452888-A (GB)
Title: Fluid actuated vibratory device
IPC: B06B1/12
Filed: 1972-08-19
Abstract: 1452888 Vibrators VERENIGDE BEDRIJVEN TANKFABRIEK-KOOIMAN NV and J W A WESTWOOD 13 Nov 1973 [19 Aug 1972 (2) 22 Aug 1972] 38770/72 38771/72 and 38998/72 Heading F1M [Also in Division F2 ] A vibratory device, as used e.g. with vibratory conveyers, comprises a hollow cylinder having an internal bearing sleeve, a piston axially slidable in the cylinder, an inlet for pressurized fluid intermediate the ends of the cylinder, a pair of outlet ports for exhaust of pressurized fluid disposed at opposite axial sides of the inlet respectively, a pair of passageways in the piston communicating with opposite ends of the cylinder respectively and being individually communicable with the inlet, the sleeve having a pair of outlet openings at positions circumferentially remote from the outlet ports respectively and there being passages whereby the fluid can flow, from the outlet openings to they outlet ports respectively, around the sleeve. The device shown in Fig. 1 comprises a piston 24 slidable within a cylinder 10 closed by endplates 11, 12 with a central inlet port 14 and two outlet ports 15, 16 with their axes at right angles to that of the inlet port 14. Within the cylinder there are two axially spaced bearing sleeves 17, 18 defining between them an annular groove 19 which communicates with the inlet port 14. These sleeves may be made from p.t.f.e. or lead bronze impregnated with graphite. Axially aligned with the outlet ports 15, 16 are two further annular grooves, extending around the outer surfaces of the sleeves 17, 18 and communicating with a pair of outlet openings (22) Fig. 2 (not shown), in the sleeves. These openings (22) extend to the internal surfaces of the sleeves 17, 18 and are positioned diametrically opposite the outlet ports 15, 16. The piston 24 has two L-shaped passageways 25, 26 communicating with the opposite end working chambers 27, 28 in the cylinder 10. When the piston 24 moves axially in one direction from its central position, one of the passageways 25, 26 communicates with the groove 19. When the piston 24 is in its central position (as shown), neither passageway 25, 26 can communicate with the groove 19. However when pressurized air is applied to the inlet port 14, some leakage flow between the piston 24 and the sleeves 17, 18 can take place so as to build up a slight overpressure in one of the chambers 27, 28. In use, pressurized air is applied to the inlet port 14 and will reach one end of the cylinder 10 through one of the passageways 25, 26 thus causing the piston to move. When it has moved a predetermined axial distance, the other passageway will communicate with the groove 19 and the inlet port 14 and thus admit pressurized air to the other end of the cylinder. The rate of vibration of the piston is principally dependent on the pressure of the air entering the cylinder and the mass of the piston. In an alternative embodiment, Fig. 3, exhaust ports 66, 67 in the housing are provided with adjustable throttle valves 68, 69. Rotation of a cap 78 of these valves varies the distance between two complementary tapered surfaces and thus provides a variable restriction to any fluid flowing out of the respective exhaust port through bores 76, 77, by means of which the frequency and amplitude of the oscillation of the piston can be controlled. The valves 68, 69 can be adjusted differently so that the average pressures in the two working chambers are different, resulting in a preferred direction of energy transmittance. The air exhausting from the valves is directed back over the outer surface of the device for cooling purposes. In further embodiments Figs. 4 and 5 (not shown) a preferred direction of energy transmit-  tance is obtained by using exhaust ports of different diameter or of different axial distances from the inlet port. Compressed air-actuated spring devices Fig. 6 (not shown) can be provided in the end-plates to co-operate each cycle of vibration with the piston and by controlling the airpressure in these devices the characteristics of the vibrations can be regulated.