Reduced waiting time hydraulic drilling jar

US5318139A · kind A · utility

Inventor

• Robert W. Evans · Leonidas, US

Key dates

• Filing date: Apr 29, 1993
• Grant date: Jun 7, 1994
• Expiry date: Apr 29, 2013

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F16F9/512
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

A reduce waiting time drilling jar 1 includes a mandrel 2, a housing 3 telescopingly positioned about the mandrel 2, and first and second pistons 89, 111 positioned axially between the mandrel 2 and the housing 3. The pistons 89, 111 are spaced longitudinally apart, forming a substantially sealed chamber 88 therebetween. The first piston 89 has a first and second substantially parallel flow passage 94, 200 formed therein and extending longitudinally therethrough to provide first and second flow characteristics. A valve 204 is hydraulically connected to the second flow passage 200. The valve 204 is translatable between first and second operating positions, wherein fluid flows relatively freely through the second flow passage 200 in the first operating position, but is restricted in the second operating position. A pressure relief valve 206 is hydraulically coupled to the substantially sealed chamber 88, and mechanically coupled to the valve 204, wherein movement of the pressure relief valve 206 biases the valve 204 between its first and second operating positions in response to the pressure in the chamber 88 rising above a preselected value.