Logging while drilling tools utilizing magnetic positioner assisted phase shifts

Claim 1

An apparatus for use in a borehole having borehole fluid flowing therethrough, said tool comprising: a) a brushless DC motor having a rotating drive shaft; b) an encoder means including a stator, and a rotor coupled to said rotating drive shaft, said rotor rotating relative to said stator thereby creating a signal in the borehole fluid; c) a position sensor coupled to said rotating drive shaft of said brushless DC motor, said position sensor providing indications related to the rotational position of said brushless DC motor; d) motor drive circuitry coupled to and driving said brushless DC motor; e) a magnetic positioner means coupled to said rotating drive shaft, said magnetic positioner means having first inner magnets of a first polarity extending in a first arc, second inner magnets of a second polarity extending in a second arc, first outer magnets of said first polarity extending in a third arc, and second outer magnets of said second polarity extending in a fourth arc, said inner magnets rotating relative to said outer magnets; and f) a microprocessor means coupled to said position sensor and coupled to said motor drive circuitry, said microprocessor means for causing said motor drive circuitry to provide drive signals to said brushless DC motor based on actual rotational positions of said brushless DC motor as provided by said indications of said position sensor, and upon desired rotational positions as determined by said microprocessor, wherein, said microprocessor encodes data by providing drive signals which cause said brushless DC motor to decelerate over a first predetermined period of time, and to accelerate over a second predetermined period of time, and said microprocessor chooses said first predetermined period of time to substantially include when said inner magnets are at first positions relative to said outer magnets, which first positions cause deceleration of said drive shaft, and said microprocessor chooses said second predetermined period of time to substantially include when said inner magnets are at second positions relative to said outer magnets which second positions cause acceleration of said drive shaft.

Claim 2

An apparatus for use in a borehole having borehole fluid flowing therethrough, said tool comprising: a) a brushless DC motor having a rotating drive shaft; b) an encoder means including a stator, and a rotor coupled to said rotating drive shaft, said rotor rotating relative to said stator thereby creating a signal in the borehole fluid; c) a position sensor coupled to said rotating drive shaft of said brushless DC motor, said position sensor providing indications related to the rotational position of said brushless DC motor; d) motor drive circuitry coupled to and driving said brushless DC motor; e) a magnetic positioner means coupled to said rotating drive shaft, said magnetic positioner means having first inner magnets of a first polarity extending in a first arc, second inner magnets of a second polarity extending in a second arc, first outer magnets of said first polarity extending in a third arc, and second outer magnets of said second polarity extending in a fourth arc, said inner magnets rotating relative to said outer magnets; and f) a microprocessor means coupled to said position sensor and coupled to said motor drive circuitry, said microprocessor means for causing said motor drive circuitry to provide drive signals to said brushless DC motor based on actual rotational positions of said brushless DC motor as provided by said indications of said position sensor, and upon desired rotational positions as determined by said microprocessor, wherein, said microprocessor encodes data by providing drive signals which cause said brushless DC motor to decelerate over a first predetermined period of time, and to accelerate over a second predetermined period of time, and said microprocessor chooses said first predetermined period of time to substantially include when said inner magnets are at first positions relative to said outer magnets, which first positions cause deceleration of said drive shaft, and said microprocessor chooses said second predetermined period of time to substantially include when said inner magnets are at second positions relative to said outer magnets which second positions cause acceleration of said drive shaft.

Claim 13

A method for generating signals in a system having borehole fluid moving through a borehole by using a borehole tool having a brushless DC motor with a drive shaft which is coupled to and drives a modulator, a position sensor coupled to the brushless DC motor for sensing the position of the motor, a microprocessor means coupled to the position sensor and to the brushless DC motor in a feedback loop, with the microprocessor means controlling the movement of the brushless DC motor based on the position of the motor and a desired position of the motor, and a magnetic positioner means coupled to the drive shaft, said magnetic positioner means having first inner magnets of a first polarity extending in a first arc, second inner magnets of a second polarity extending in a second arc, first outer magnets of said first polarity extending in a third arc, and second outer magnets of said second polarity extending in a fourth arc, with said inner magnets rotating relative to said outer magnets, said method comprising: a) causing said microprocessor to generate first signals for said brushless DC motor to cause said brushless DC motor to rotate at a first speed; b) causing said microprocessor to generate second signals for said brushless DC motor to cause said brushless DC motor to decelerate from said first speed during a first period of time between a first instant when said first inner magnets of said first polarity are directly opposite said second outer magnets of said second polarity, and a second instant when said first inner magnets of said first polarity are directly opposite said second outer magnets of said first polarity, said DC motor decelerating to a second speed; and c) causing said microprocessor to generate third signals for said brushless DC motor to cause said brushless DC motor to accelerate from said second speed during a second period of time between said second instant and a third instant when said first inner magnets of said first polarity are directly opposite said second outer magnets of said second polarity.

Claim 14

A method for generating signals in a system having borehole fluid moving through a borehole by using a borehole tool having a brushless DC motor with a drive shaft which is coupled to and drives a modulator, a position sensor coupled to the brushless DC motor for sensing the position of the motor, a microprocessor means coupled to the position sensor and to the brushless DC motor in a feedback loop, with the microprocessor means controlling the movement of the brushless DC motor based on the position of the motor and a desired position of the motor, and a magnetic positioner means coupled to the drive shaft, said magnetic positioner means having first inner magnets of a first polarity extending in a first arc, second inner magnets of a second polarity extending in a second arc, first outer magnets of said first polarity extending in a third arc, and second outer magnets of said second polarity extending in a fourth arc, with said inner magnets rotating relative to said outer magnets, said method comprising: a) causing said microprocessor to generate first signals for said brushless DC motor to cause said brushless DC motor to rotate at a first speed; b) causing said microprocessor to generate second signals for said brushless DC motor to cause said brushless DC motor to decelerate from said first speed during a first period of time between a first instant when said first inner magnets of said first polarity are directly opposite said second outer magnets of said second polarity, and a second instant when said first inner magnets of said first polarity are directly opposite said second outer magnets of said first polarity, said DC motor decelerating to a second speed; and c) causing said microprocessor to generate third signals for said brushless DC motor to cause said brushless DC motor to accelerate from said second speed during a second period of time between said second instant and a third instant when said first inner magnets of said first polarity are directly opposite said second outer magnets of said second polarity.