| 摘要 |
<p>The method and apparatus for generating seismic vibrations in a liquid includes an electronically controlled, hydraulically powered generator (10) that includes a piston assembly (16) reciprocally mounted on a cylindrical post (14) in a generator housing (12). The control apparatus includes a control valve (18) that is located very close to the piston assembly (16) thereby reducing the volume of the passageways (48, 56) extending to the piston assembly (16) so that the cycle rate of the piston assembly (16) can be very rapid and can be changed accurately and quickly. An extended life is provided by releasing the high pressure fluid driving the piston assembly (16) prior to impact between the piston assembly (16) and the post (14) and by providing trapped volumes of fluid in the chambers (84, 88) to damp the movement of the piston assembly (16) toward the post (14).</p> |
