| 摘要 |
A down-hole tool 10 comprising a fluid-actuated piston 20 and a motor-driven valve 18. The fluid-actuated piston 20 is operatively associated with a reciprocating mass 22. The motor-driven valve 18 is configured to supply actuating fluid sequentially to drive the piston 20 downwards and upwards. The mass 22 may be associated with a drill bit or cutting structure. A method of reciprocating a mass 22 in a down-hole tool 10 comprising cycling a motor-driven valve 18 between a first configuration and a second configuration. In the first configuration actuating fluid pressure drives a piston 20 associated with the mass 22 downwards. In the second configuration actuating fluid pressure drives the piston 20 upwards. Figure 1 |
