| 摘要 |
In the field of seismic exploration, compressed-air guns may be used as sound sources. Known air guns employed complex valving and were wasteful of compressed air. The air gun sound source of this invention is of simple construction and is economical of compressed air. The gun (10) consists of an elongated housing (34) that has at least one radially-positioned exhaust port. The housing is charged with a volume of compressed air. A hollow cylindrical actuator (60) is mounted inside the housing and may be hydraulically or pneumatically driven within the housing in longitudinal strokes. The actuator has at least one radially positioned aperture (88) alignable with the exhaust port. A valve or sealing pad (96) is mounted in each aperture. An orifice (104) is cut into each pad. At one end of an actuator stroke, the valve blocks the exhaust port in the housing. When the shuttle is driven from one end of the housing to the other, as the valve orifice passes by the exhaust port, the exhaust port is opened momentariliy to allow the explosive escape of some of the compressed air in the gun. As the actuator completes its stroke to the other end of the housing, the exhaust port is again blocked. |
