| 摘要 |
1,274,729. Seismic energy generators. WESTERN GEOPHYSICAL CO. OF AMERICA. 30 Oct., 1969 [29 Nov., 1968; 7 April, 1969], No. 53316/69. Heading H4D. [Also in Division F1] Combustion products resulting from the firing of a marine seismic energy generator comprising an expandable combustion chamber in which a combustible mixture is detonated are exhausted from the chamber only after a predetermined time, when the chamber internal pressure has decreased to a level below the ambient hydrostatic pressure. This ensures that the combustion products cushion the collapse of the chamber immediately after the detonation and chamber expansion, thereby preventing generation of a disturbing seismic rarefaction pulse. The generator may be similar to that in Specification 1,246,350, comprising an expandable sleeve supported by end seals mounted on tubes through which cooling water flows, and having a vacuumoperated exhaust system. An exhaust valve, preferably actuated by the slave unit of Fig. 6, has its opening and closing controlled by a timing circuit. In Fig. 6, solenoid valve 43 is operated in timed relation to the firing, when the chamber pressure is approaching its minimum value (below atmospheric, due to cooling and condensation of combustion products), thereby applying the pressure of one of the fuel gases from conduit 41 to diaphragm 202 to lift exhaust valve 222 from its seat 224. Exhaust gases from a coupling 52 with the combustion chamber (not shown) then pass via flamearrester 112 and the valve 222 to evacuated outlet 46. Solenoid valve 43 is then returned to the position shown to expose diaphragm 202 to the low pressure in outlet 46 and so close exhaust valve 222. Seismic recording equipment, exhaust valve timing circuits, and vacuum pumping equipment may be carried on a ship used to tow the generator. Reference has been directed by the Comptroller to Specification 1,164,402. |
