GB1451161A - Pressurised fluid driven vibrator - Google Patents

Abstract

1451161 Vibrators POCLAIN 3 Jan 1974 [15 Jan 1973] 00193/74 Heading F2X A fluid-driven vibrator particularly suitable for the fatigue testing of materials comprises a pump 1, a fluid reservoir 2, a fluid receiver 3 consisting of a cylinder 6 fixed to a structure 7, e.g. a solid concrete mass, by a shaft 8, and a piston rod 10 connected to a body 9 of determined mass by a pin 11 and stirrup 12, a suction conduit 14 connecting the pump 1 to the reservoir 2, a delivery conduit 5 connecting the pump 1 to the drive chamber 4 of the fluid receiver 3, and a pressure-limiting device 15 for controlling the fluid pressure in the conduit 5. The device 15 is constituted by a 2-position distributor comprising a slide 16 under the opposed effects of the fluid in an inlet chamber 17 and a return member, e.g. a spring 18, and by four main conduits 19 connecting conduit 5 to the reservoir 2 via a main valve 23 controlled by the opposed effects of a return member, e.g. a spring 32, and the fluid pressure between the pump 1 and the valve 23, 20 connecting conduit 5 to the inlet chamber 17, 21 being connected to conduit 20 between an orifice 24 and the connection of conduit 20 to conduit 5, and 22 connecting the distributor 15 to the reservoir 2. An adjustable control valve 25 is disposed in conduit 20 downstream of orifice 24 and is controlled by a return member, e.g. a spring 38, and the fluid pressure in the conduit 20 between the orifice 24 and the valve 25. Conduits 20, 21 are connected by a conduit 26 containing a non-return valve 27 allowing passage of fluid from conduit 20 towards conduit 21. In the first position of the distributor 15 in which the effect of the spring 18 predominates, conduits 21, 22 are obturated by the slide 16, whilst in the second position in which the fluid pressure in the inlet chamber 17 predominates, conduits 21, 22 are in communication. A second orifice 28 is disposed in conduit 20 between the connections of this conduit to the conduits 5 and 21, respectively. Pressures and counter-pressures controlling the valves 23, 25 are shown schematically by conduits 48, 49 and 50, 51 respectively, whilst an escape conduit 42 is shown schematically connecting the chamber of distributor 15 in which the spring 18 is disposed to the reservoir 2. When operation of the pump 1 commences, fluid is delivered via conduit 5 to drive chamber 4 and repels the piston 10 to place the body 9 in abutment with a face 13 of the structure 7. As the fluid pressure is built up, the fluid passes through the valves 23, 25 and the orifices 24, 28 and eventually repels the slide 16 of distributor 15 sufficiently for conduits 21, 22 to be placed in communication whereupon the fluid contained in drive chamber 4 undergoes a drop in pressure, becoming zero after a certain lapse of time. The elastic reaction has by this time repelled the body 9 out of abutment with face 13. Furthermore, the spring 18 acts on the slide 16 causing the fluid of inlet chamber 17 to be delivered through the non-return valve 27 to the reservoir 2. A new operational cycle then commences. During each cycle, a pressurization of the fluid in the drive chamber 4 is followed by a communication of the chamber with the reservoir 2. In Figs. 2 to 5 (not shown) the valves 23, 25 are illustrated in detail, in four successive positions, being mounted together with the orifices 24, 28 in a single valve body. In Fig. 6 (not shown) the fluid receiver is double-acting with two fluid circuits of the type described above provided, being connected to the receiver on opposite sides of the piston. Synchronization of the circuits is obtained by adopting a single distributor.