GB1389068A - Vibrator devices - Google Patents

Abstract

1389068 Vibrators A J WESTWOOD 17 March 1972 12535/72 Heading F2X A vibrator for use with apparatus such as vibratory conveyers comprises a piston 10 slidable in a cylinder 11 in which there are inlet ports 14, 15 and outlet ports 16, 17 through which air or other gaseous fluid under pressure is supplied to and exhausted from the ends of the cylinder 11, the control of fluid flow through the ports being determined by the position of the piston 10 in the cylinder 11. The spacing of the two outlet ports 16, 17 is rather less than the length of the piston 10, so that as shown in Fig. 1, the piston can block both the outlet ports when it is mid-way between the ends of the cylinder. The piston 10 has two L-shaped passages 18, 19, the axially extending portions of which extend to opposite ends of the piston. The spacing of the radial portions of the passages 18, 19 is such that in the position shown, neither of the passages 18, 19 is in direct communication with its associated inlet port 14, 15. The piston 10, however, has an additional passage 20 formed as a groove in its outer surface and communicating with the passage 18, also with the inlet port 14 when the piston is in the position shown. The purpose of this additional passage 20 is to facilitate starting of the device. It is common for the piston 10 to come to rest in the position shown and application of fluid under pressure to inlet ports 14, 15 would create no tendency for the piston to move, were it not for the passage 20 which allows a restricted flow into the passage 18. This in turn causes an increase in pressure at one end of the cylinder, thus moving the piston and beginning the vibrating cycle. The inlet ports 14, 15 are connected by an annular internal groove within the cylinder and the passage 20 which is disposed at an angle to the axis of the piston 10 causes incremental rotation of the piston each time the passage 20 passes the inlet groove. In an alternative construction (Fig. 3, not shown), the additional passage (22) is a groove in the cylinder wall communicating directly with the outlet port 17.