Earth boring apparatus and method with control valve
US4834193A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 22, 1987 |
| Grant date | May 30, 1989 |
| Priority date | — |
| Expiry date | Dec 22, 2007 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B21/103
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
An earth boring apparatus has a pneumatically operated earth boring tool, a flexible conduit or drill pipe connected to the tool and to a source of pneumatic fluid. The tool has an earth boring member and a reciprocally movable hammer positioned in the tool to apply a percussive force. A valve assembly in the flexible conduit or drill pipe substantially adjacent to the tool between the tool and the source of pneumatic fluid controls the flow of pneumatic fluid to the tool. The valve assembly has a pneumatic pressure-operated valve which is operable in response to the pressure of pneumatic fluid in the flexible conduit or drill pipe to be opened to permit flow of pneumatic fluid to the tool at a predetermined operating pressure to transmit an initial pulse of pneumatic fluid to initiate operation of the hammer. The valve is kept open at a lower pressure than that required to open it. One form of the valve is a pressure operated valve, spring-loaded toward closed position, which opens at a first predetermined pneumatic pressure permitting flow to said tool and closes at a second, substantially lower, pneumatic pressure. Another form of the valve means has a valve, spring-loaded towar…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.