Apparatus for automatically controlling weight-on-bit

Claim 2

In apparatus for automatically controlling weight on the bit in a rotary drilling rig including: a. cable drum for spooling the ''''fast'''' end of a tensioned cable bearing a portion of the weight of a drill string; b. drum rotation monitor means responsively connectable with said drum for monitoring rotation thereof; c. sensor means connected responsively with the tensioned ''''dead'''' end of said cable; d. brake for said drum; e. brake applying means connected with said brake for automatically restoring and maintaining said brake applied when said brake is not being released by a brake release means; f. brake release means connected with said brake releasing said brake; the improvement comprising: g. gate means connected with said brake release means for passing a brake release signal to said brake release means to fully release said brake and for terminating said brake release signal to fully apply said brake; h. signal generating means comprising controller means and a signal generator connected with said sensor means and said gate means for generating a brake release signal and actuating said gate means to pass said brake release signal to said brake release means responsive to sensing of a cable tension greater than a predetermined control tension; said brake release signal being sufficient to effect a full release of said brake; and i. signal length modifier means comprising a proportional response means connected with said drum rotation monitor means and said gate means for supplying to said gate means a signal responsive to both rate and degree of rotation of said drum causing said gate means to terminate passage of said brake release signal after a time interval the magnitude of which is inversely proportional to the rate at which said drum starts to rotate such that said brake is fully applied and fully released to avoid the diadvantages of partially releasing said brake; said proportional response means including a switch means, a Paschal-type filter network and a level sensor; said drum rotation monitor means being drivingly connected with said switch means that is connnected into said Paschal-type filter network; said Paschal-type filter network being connected with said level sensor that is connected with said gate means.

Claim 3

The apparatus of claim 1 wherein said level sensor comprises an electronic switch means having means rendering it conductive; said electronic switch means being serially connected with said gate means and a power source for rendering said gate means nonconductive; and said switch means is a single-pole, double throw type, and is connected into said Paschal-type filter network comprising: a. a biasing resistor and capacitor serially connected between said means rendering said electronic switch means conductive and the center pole of said switch means; b. first resistor connected with the juncture of said biasing resistor and said biasing capacitor and with a first contact of said switch means so as to discharge said biasing capacitor at a first rate when said switch means connnects said capacitor with said first contact; c. electrical common connected with the second contact of said switch means for charging said biasing capacitor at a second rate when said switch means connects said capacitor with said second contact; and d. parallel-connected resistor and capacitor serially connected with said power source and the juncture of said means rendering said electronic swith means conductive and said biasing resistor; said capacitors and said resistors being chosen such that said second rate is greater then said first rate and said biasing capacitor is charged more rapidly with more rapid switching by said switch means, said biasing capacitor being charged to a voltage such that said electronic switch means is rendered conductive; whereby said brake release signal is terminated after a time interval that is shortened by more rapidly opening and closing said switch means as by rapid acceleration of said cable drum as it starts to rotate.

Claim 4

In apparatus for automatically controlling weight on the bit in a rotary drilling rig including: a. cable drum for spooling the ''''fast'''' end of a tensioned cable bearing a portion of the weight of a drill string; b. drum rotation monitor means responsively connectable with said drum from monitoring rotation thereof; c. sensor means connected responsively with the tensioned ''''dead'''' end of said cable; d. brake for said drum; e. brake applying means connected with said brake for automatically restoring and maintaining said brake applid when said brake is not being released by a brake release means; f. brake release means connected with said brake for releasing said brake; the improvement comprising: g. gate means connected with said brake release means for passing a brake release signal to said brake release means to fully release said brake and for terminating said brake release signal to fully apply said brake; said gate means being a multivibrator that is turned on by a signal generator and turned off by a proportional response means; h. signal generating means comprising controller means and signal generator connected with said sensor means and said gate means for generating a brake release signal and actuating said gate means to pass said brake release signal to said brake release means responsive to sensing of cable tension greater than a predetermined control tension; said brake release signal being sufficient to effect a full release of said brake; and i. signal length modifier means comprising a proportional response means connected with said drum rotation monitor means and said gate means for supplying to said gate means a signal responsive to both rate and degree of rotation of said drum causing said gate means to terminate passage of said brake release signal after a time interval the magnitude of which is inversely proportional to the rate at which said drum starts to rotate such that said brake is fully applied and fully released to avoid the disadvantages of partially releasing said brake.

Claim 5

In apparatus for automatically controlling weight on the bit in a rotary drilling rig including: a. cable drum for spooling the ''''fast'''' end of a tensioned cable bearing a portion of the weight of a drill string; b. drum rotation monitor means responsively connectable with said drum from monitoring rotation thereof; c. sensor means connected responsively with the tensioned ''''dead'''' end of said cable; d. brake for said drum; e. brake applying means connected with said brake for automatically restoring and maintaining said brake applid when said brake is not being released by a brake release means; f. brake release means connected with said brake for releasing said brake; the improvement comprising: g. gate means connected with said brake release means for passing a brake release signal to said brake release means to fully release said brake and for terminating said brake release signal to fully apply said brake; said gate means being a multivibrator that is turned on by a signal generator and turned off by a proportional response means; h. signal generating means comprising controller means and signal generator connected with said sensor means and said gate means for generating a brake release signal and actuating said gate means to pass said brake release signal to said brake release means responsive to sensing of cable tension greater than a predetermined control tension; said brake release signal being sufficient to effect a full release of said brake; and i. signal length modifier means comprising a proportional response means connected with said drum rotation monitor means and said gate means for supplying to said gate means a signal responsive to both rate and degree of rotation of said drum causing said gate means to terminate passage of said brake release signal after a time interval the magnitude of which is inversely proportional to the rate at which said drum starts to rotate such that said brake is fully applied and fully released to avoid the disadvantages of partially releasing said brake.

Claim 6

The apparatus of claim 3 wherein said multivibrator is a monostable multivibrator for ensuring termination of said brake release signal and thereby providing a fail-safe, feature.

Claim 7

In apparatus for automatically controlling weight on the bit in a rotary drilling rig including: a. cable drum for spooling the ''''fast'''' end of a tensioned cable bearing a poRtion of the weight of a drill string; b. drum rotation monitor means responsively connected to said drum for monitoring rotation thereof; c. sensor means responsively with the tensioned ''''dead'''' end of said cable; d. brake for said drum; e. brake applying means connected with said brake for automatically restoring and maintaining said brake applied when said brake is not being released by a brake release means; f. brake release means connected with said brake for releasing said brake; the improvement comprising: g. gate means connected with said brake release means for passing a brake release signal to said brake release means to fully release said brake and for terminating said brake release signal to fully apply said brake; said gate means being a bistable multivibrator; h. signal generating means comprising controller means and a signal generator connected with said sensor means and said gate means for generating a brake release signal and actuating said gate means to pass said brake release signal to said brake release means responsive to sensing of cable tension greater than a predetermined control tension; said brake release signal being sufficient to effect a full release of said brake; said signal generator when energized producing a continuous signal that turns on said bistable multivibrator to effect said brake release signal; and i. signal length modifier means connected with said drum rotation monitor means and said bistable multivibrator serving as said gate means for turning off said bistable multivibrator responsive to both rate and degree of rotation of said drum causing said bistable multivibrator to terminate passage of said brake release signal; whereby said brake is fully applied and fully released to avoid the disadvantage of partially releasing said brake.

Claim 8

In apparatus for automatically controlling weight on the bit in a rotary drilling rig including: a. cable drum for spooling the ''''fast'''' end of a tensioned cable bearing a poRtion of the weight of a drill string; b. drum rotation monitor means responsively connected to said drum for monitoring rotation thereof; c. sensor means responsively with the tensioned ''''dead'''' end of said cable; d. brake for said drum; e. brake applying means connected with said brake for automatically restoring and maintaining said brake applied when said brake is not being released by a brake release means; f. brake release means connected with said brake for releasing said brake; the improvement comprising: g. gate means connected with said brake release means for passing a brake release signal to said brake release means to fully release said brake and for terminating said brake release signal to fully apply said brake; said gate means being a bistable multivibrator; h. signal generating means comprising controller means and a signal generator connected with said sensor means and said gate means for generating a brake release signal and actuating said gate means to pass said brake release signal to said brake release means responsive to sensing of cable tension greater than a predetermined control tension; said brake release signal being sufficient to effect a full release of said brake; said signal generator when energized producing a continuous signal that turns on said bistable multivibrator to effect said brake release signal; and i. signal length modifier means connected with said drum rotation monitor means and said bistable multivibrator serving as said gate means for turning off said bistable multivibrator responsive to both rate and degree of rotation of said drum causing said bistable multivibrator to terminate passage of said brake release signal; whereby said brake is fully applied and fully released to avoid the disadvantage of partially releasing said brake.

Claim 9

In apparatus for automatically controlling weight on the bit in a rotary drilling rig including: a. cable drum for spooling the ''''fast'''' end of a tensioned cable bearing a portion of the weight of a drill string; b. drum rotation monitor means responsively connectable with said drum for monitoring rotation thereof; c. sensor means connected responsively with the tensioned ''''dead'''' end of said cable; d. brake for said drum; e. brake applying means connected with said brake for automatically restoring and maintaining said brake applied when said brake is not being released by a brake release means; f. brake release means connected with said brake for releasing said brake; the improvement comprising: g. gate means connected with said brake release means for passing a brake release signal to said brake release means to fully release said brake and for terminating said brake release signal to fully apply said brake; said gate means being a monostable multivibrator that produces a plurality of discrete pulses of a first time duration, each said pulse effecting passage of said brake release signal and termination thereof when not otherwise terminated; h. signal generating means comprising controller means and signal generator connected with said sensor means and said gate means for generating a brake release signal and actuating said gate means to pass said brake release signal to said brake release means responsive to sensing of cable tension greater than a predetermined control tension; said brake release signal being sufficient to effect a full release of said brake; and i. signal length modifier means connected with said drum rotation monitor means and said gate means for supplying said gate means a signal responsive to both rate and degree of rotation of said drum causing said gate means to terminate passage of said brake release signal; whereby said brake is fully applied and fully released to avoid the disadvantages of partially releasing said brake; said signal length modifier means being operable to render said monostable multivibrator nonconductive responsive to rate and deGree of rotation of said drum to shorten said first time duration as needed to effect optimum control of the weight-on-bit and alleviate difficulties with over controlling.

Claim 10

In apparatus for automatically controlling weight on the bit in a rotary drilling rig including: a. cable drum for spooling the ''''fast'''' end of a tensioned cable bearing a portion of the weight of a drill string; b. drum rotation monitor means responsively connectable with said drum for monitoring rotation thereof; c. sensor means connected responsively with the tensioned ''''dead'''' end of said cable; d. brake for said drum; e. brake applying means connected with said brake for automatically restoring and maintaining said brake applied when said brake is not being released by a brake release means; f. brake release means connected with said brake for releasing said brake; the improvement comprising: g. gate means connected with said brake release means for passing a brake release signal to said brake release means to fully release said brake and for terminating said brake release signal to fully apply said brake; said gate means being a monostable multivibrator that produces a plurality of discrete pulses of a first time duration, each said pulse effecting passage of said brake release signal and termination thereof when not otherwise terminated; h. signal generating means comprising controller means and signal generator connected with said sensor means and said gate means for generating a brake release signal and actuating said gate means to pass said brake release signal to said brake release means responsive to sensing of cable tension greater than a predetermined control tension; said brake release signal being sufficient to effect a full release of said brake; and i. signal length modifier means connected with said drum rotation monitor means and said gate means for supplying said gate means a signal responsive to both rate and degree of rotation of said drum causing said gate means to terminate passage of said brake release signal; whereby said brake is fully applied and fully released to avoid the disadvantages of partially releasing said brake; said signal length modifier means being operable to render said monostable multivibrator nonconductive responsive to rate and deGree of rotation of said drum to shorten said first time duration as needed to effect optimum control of the weight-on-bit and alleviate difficulties with over controlling.