Patent GB-394991-A (GB)
Title: An improved method of and means for automatically regulating the drill pressure in deep-boring plant
IPC: E21B19/08
Filed: 1932-01-04
Abstract: 394,991. Bore-hole apparatus. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Haniel & Lueg Ges.; Grafenberg, D³sseldorf, Germany.) Jan. 4, 1932, No. 171. [Class 85.] In an automatically-controlled deep-boring plant, means are provided whereby, when the torque exceeds a given limit, a lift is applied to the upper end of the drill rods, while when the pressure of the bit falls below a given limit, the brake on the draw-work drum is released to allow the drill cable to be paid out. In Fig. 1 the free end of the drill rope is connected to a piston 3 in a cylinder 4, the piston having a lost motion connection with a valve 9 ; air &c. passes from a vessel 6 through reducing valve 25 to maintain a minimum pressure in cylinder 4. If the drill pressure falls below a given minimum, piston 3 rises and opens valve 9, air &c. then passing through pipes 10, 11 to cylinder 12 and releasing the drawworks brake 15. If the torque exceeds a given maximum, through cable &c. 19, controlled as by the governor of the prime mover, the lever 56, Fig. 6, of a regulator R is depressed against the resistance of a fluidpressed diaphragm 54 and, through valve 53, fluid is admitted to means whereby valve 25, Fig. 1, is fully opened and excess-pressure relief valve 27 is closed, whereby high pressure fluid is admitted to cylinder 4 and a lift is applied to the drill rods. The high and low pressure fluid may be supplied from separate vessels. In a modification, the valves 25, 27 are replaced by a single valve controlled through a diaphragm from the regulator R. A variablyacting weight may replace the device 3, 4. Where the prime mover is an internal-combustion engine, excessive movement of the fuel pump piston due to excessive torque may cause admission of fluid to a cylinder to actuate cable &c. 19. The brake controlling means 12 may be replaced by an electromagnet and a torque-controlled electromagnet may also operate the regulator R. With a Diesel or steam engine drive, the regulation may be effected by a three-way cock controlled by a solenoid which is supplied with current by a dynamo driven by the engine and excited when the load on the engine exceeds a given limit. In Fig. 13, the piston 3 and cylinder 4 are replaced by an electromagnet 43 the power supply to which is controlled by a solenoid 22 energized from the circuit of the main driving motor E through an induction coil ; alternatively, the electromagnet 42 may be in series with the main driving motor or be in the shunt or compound circuit of the motor, or it may have several windings arranged in different circuits. In all cases, the lifting means 3, 4, Fig. 1, or 42, Fig. 13, may also act, as though a solenoid 49, Fig. 13, to engage a clutch or start an auxiliary engine &c. to drive the drawworks drum and therebv give an additional lift. In Fig. 16, the free end of the drill cable is wound on a drum 181 with a worm gear engaged by a worm 63 connected by a thrust bearing 65 to the piston 3<1>. Compound pistons 73, 74, have their small, ends constantly open to the pressure supply while their large ends are normally open to such supply to hold the brake 17 engaged and a clutch 69 disengaged. If the drill pressure is insufficient the increased load on the cable causes piston 3<1> to actuate valve 71, open the upper face of piston 73 to exhaust and free the brake 17. If the drill pressure is excessive, piston 3<1> opens exhaust valve 71<1> and causes clutch 69 to be engaged, thereby driving worm 63 and winding up the drill rope. In a modification, valves 71, 71<1> are replaced by switches controlling an electromagnet to free the brake and an electric motor for driving the worm 63.