EARTH BORING MACHINE WITH MULTI-MOTOR DRIVE
United States Patent 3766995
An earth boring method using a multiplicity of motors provides a wide range of rotational torques and speeds for optimum drilling performance. One of the multiplicity of motors is supplied with power to drive the rotary drill string at high speed for drilling a pilot hole with the other motors disengaged from the bull gear. When enlarging the pilot hole into a large diameter hole two or more of the motors are supplied with power and engaged with the bull gear.
US Patent References:
Raise drilling method and mechanism
Cannon et al. - November 1965 - 3220494
EARTH DRILLING EQUIPMENT
Bland - February 1969 - 3426857
Hydraulic well-drilling apparatus
Brantly - March 1942 - 2276016
Portable drilling rig
Bury - July 1950 - 2516182
Arrangement for connecting a tubular member in a well string
Hasha - November 1966 - 3282339
Raise drilling method and mechanism
Cannon et al. - November 1965 - 3220494
EARTH DRILLING EQUIPMENT
Bland - February 1969 - 3426857
Hydraulic well-drilling apparatus
Brantly - March 1942 - 2276016
Portable drilling rig
Bury - July 1950 - 2516182
Arrangement for connecting a tubular member in a well string
Hasha - November 1966 - 3282339
Inventors:
Young, James W. (Irving, TX)
Arrington, Thomas L. (Dallas, TX)
Arrington, Thomas L. (Dallas, TX)
Application Number:
05/191000
Publication Date:
10/23/1973
Filing Date:
10/20/1971
View Patent Images:
Export Citation:
Assignee:
Dresser Industries, Inc. (Dallas, TX)
Primary Class:
Other Classes:
173/216
International Classes:
E21B3/02; E21B7/00; E21B7/28; E21B3/00; E21C23/00
Field of Search:
175/53,95,170,171,122 173/163,57
US Patent References:
Primary Examiner:
Champion, Marvin A.
Assistant Examiner:
Favreau, Richard E.
Parent Case Data:
This is a division of application Ser. No. 22,768, filed Mar. 26, 1970, now abandoned.
Claims:
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows
1. A method of driving a rotary drill column for boring a large diameter hole between an upper level and a lower level underground, comprising:
1. A method of driving a rotary drill column for boring a large diameter hole between an upper level and a lower level underground, comprising:
Description:
BACKGROUND OF THE INVENTION
This invention relates to the art of earth boring and more particularly to a drive system for earth boring.
Earth boring operations may require a wide range of drilling speeds and torques. For example, it is often necessary to change from one size bit to a bit of another size. Since each size bit operates best at a particular speed and torque, it is desirable to be able to adjust the drive speed and torque rather than drill under less then optimum drilling conditions. Changes in speed and torque may also be required when a new formation is encountered because the character of the formations determines optimum drilling speed and torque requirements. It may be necessary to change drilling speed and torque to avoid undesirable operating conditions such as critical resonant vibrations. Speed and torque adjustments are extremely important when making up or breaking out sections of the drill string. It can be appreciated that a flexible drive system for an earth boring machine will improve and simplify the drilling operation.
The earth boring machine must be simple, reliable and highly flexible and must be able to provide the range of drilling speeds and torques required. In addition, the boring machine should include a fast, simple, and dependable means of changing drilling speeds and torques.
A specialized earth boring machine that must operate under strict environmental conditions and perform a wide range of drilling operations is used for drilling raises between levels of an undergound mine. This type of boring machine is usually referred to as a raise drill, deriving its name from the finished product. A raise drill must meet all the requirements of an earth boring machine plus the requirements of being compact and able to operate reliably in the confines of an underground mine. The raise drill should operate with a minimum of service because of the difficulty of servicing in an underground mine and the loss of valuable drilling time. The raise drill must be adaptable to being moved in the elevators and narrow passageways of the mine. The need for simplicity, reliability, and safety is extremely important and must be provided without reducing the mechanical operation of the machine. When a pilot hole is being drilled, the drive system should operate at high speed and low torque and when the pilot hole is being enlarged by a reaming operation, the drive system should operate at slow speed and high torque. Other variations in speed and torque are required under various drilling conditions.
DESCRIPTION OF THE PRIOR ART
The drive systems of the prior art do not include a flexible drive system that will produce the wide range of drilling speeds and torques required. In general the prior art drive systems are bulky, inefficient and lack the flexibility needed.
A general summary of raise drilling is provided in U.S. Pat. No. 3,220,494 to R. E. Cannon et al., patented Nov. 30, 1965. The "raise" hole is obtained by drilling a relatively small pilot hole down to a lower level of the mine. The pilot bit is removed and a large raise cutter head or raise bit attached. The pilot hole is enlarged to the desired size by rotating and hydraulically raising the large diameter bit along the pilot hole.
One of the prior art drive systems is represented by U.S. Pat. No. 3,446,284 to N. D. Dyer et al., patented May 27, 1969. This drive system includes a hydraulic motor connected to the rotary member by a chain drive. The speed and torque may be varied by changing the size of the chain sprockets interconnecting the hydraulic motor and rotary member. It can be appreciated that this drive system includes a number of disadvantages. Among these disadvantages is the time and difficulty of changing sprockets in order to effect a change in drill speed and torque.
Another of the prior art drive systems is represented by U.S. Pat. No. 3,454,114 to L. B. Poage, patented July 8, 1969. This drive system includes a motor that drives the rotary member through a complex mechanical transmission system. The mechanical transmission is complex and will not provide the changes in speed and torque required to produce optimum drilling. Because of the elaborate gearing means employed the transmission is subject to mechanical failure.
In U.S. Pat. No. 3,460,638 to Millsapps, Jr., patented Aug. 12, 1969, a drive system is shown that includes fluid motors connected to a kelly. The kelly is in turn connected to the drill string. This drive system also lacks the flexibility and simplicity required to produce optimum drilling.
SUMMARY OF THE INVENTION
The present invention provides an improved drive system that is extremely flexible and reliable. The system is compact, dependable and does not include any complex or elaborate planetary or sprocket mechanisms.
This invention provides a simple drive system for producing the range of speeds and torques required in an earth boring operation. The drilling speed and torque may be adjusted by changing the hydraulic and/or electric circuit supplying power to the drive motors. The drive system of this invention will produce high speed, low torque when drilling a pilot hole and high torque, slow speed when enlarging the pilot hole by a reaming operation. The drive system also provides the flexibility required for make up and break out of sections of the drill string as well as assuring that the drilling operation may proceed under optimum speed and torque conditions.
A multiplicity of motors are connected to the drill head and arranged to transmit rotary motion to the drill string. The speed and torque may be adjusted by changing the circuit delivering power to the various motors. This allows a combination of motors to be used that will provide the drive best suited to the drilling operation. All the power may be diverted to a single motor for high speed drilling or the power may be diverted to all of the motors to provide high torque, slow speed drilling.
It is therefore an object of the present invention to provide an earth boring machine with an improved drive system.
It is a further object of this invention to provide an earth boring machine drive system that is flexible and will produce a wide range of drilling speeds and torques.
It is a still further object of this invention to provide an earth boring machine that is compact, reliable and uncomplicated.
It is a still further object of this invention to provide an improved drive system for a raise drill.
It is a still further object of the present invention to provide an earth boring system that will allow the drilling operation to be carried out under optimum conditions.
The above and other objects and advantages will become apparent from a consideration of the following detailed description when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a raise drill including an embodiment of the drive system of this invention.
FIG. 2 shows one embodiment of the drive system of this invention.
FIG. 3 is another view of the embodiment of the invention shown in FIG. 2.
FIG. 4 is a hydraulic circuit of the drive system shown in FIGS. 2 and 3.
FIG. 5 is another embodiment of the present invention.
FIG. 6 is a hydraulic circuit of the embodiment shown in FIG. 5.
FIG. 7 is another embodiment of the drive system of this invention.
FIG. 8 is an electrical circuit diagram of the embodiment of FIG. 7.
FIG. 9 is an embodiment of this invention including both hydraulic and electric motors.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, a raise drill including one embodiment of the drive system of the present invention is shown generally at 10. The raise drill 10 is anchored to the ground by a base element 11. In order to be certain that raise drill 10 is firmly affixed to the ground, a concrete foundation pad may be installed and base element 11 firmly attached thereto. Supports 12 and 12' are attached to base 11 and held in place by braces 13 and 13'.
A carriage 14 is mounted for travel along supports 12 and 12'. Carriage 14 may be moved along support 12 and 12' by means well known in the art such as a double acting hydraulic thrust cylinder 15 connected between carriage 14 and base element 11. Carriage 14 supports drill head 16 and drive system 17. A rotary drill column 18 is connected to drill head 16 and is in position for drilling down. The individual sections of rotary drill column 18 may be attached and removed during the drilling operation according to the system shown in U.S. Pat. No. 3,446,284 to N. D. Dyer et al., patented May 27, 1969.
The drive system 17 rotates drill head 16 and drill column 18 attached thereto. In raise drilling, a small pilot hole is drilled to another level of the mine. The small pilot bit is removed and a larger raise bit attached. The raise bit is then rotated and moved upward to enlarge the pilot hole to the desired size. It can be appreciated that the raise drilling operation requires a wide range of drilling speeds and torques. A high speed, low torque drive is requred when drilling the pilot hole and a slow speed, high torque drive is required during the reaming operation when the pilot hole is being enlarged. The drilling speed and torque may be adjusted to maintain optimum drilling conditions. In addition, changes in speed and torque are required when sections of the drill column are being added or removed and the speed and torque must be adjusted when changes in drilling conditions are encountered. Although the drilling operation has been shown as drilling directly downward, it is to be understood that a similar operation could be performed upward or at various angles to the vertical.
The present invention provides a drive system that includes sufficient flexibility to enable the various drilling operations to be carried out without elaborate planetary gear systems or time consuming gear and sprocket changes. A plurality of motors are connected to the drill head to provide the power for rotating the drill column. Power is applied through various combinations of motors to provide the desired drilling speeds and torques.
Referring now to FIG. 2, one embodiment of the drive system of the present invention is shown in greater detail. A multiplicity of hydraulic motors mounted on the raise drill carriage drive the drill head and rotate the drill column. The speed and torque may be varied by adjusting the ydraulic pressures and flow volumes through each individual motor. In addition, the speed and torque may be adjusted by variations of the hydraulic circuit. For slow speed, high torque drive, the hydraulic circuit supplies the motors in parallel with the flow through each motor adjusted according to the resistance encountered. For high speed, low torque drive, the hydraulic fluid is channeled through a single motor. Three motors 19, 20 and 21 drive the drill head 16 and supply the power to rotate the drill column. For slow speed, high torque the hydraulic fluid is supplied to motors 19, 20 and 21 parallel. When the high speed, low torque drive is required, as when drilling a pilot hole, the hydraulic fluid is channeled through motor 19 only. The drill head 16 includes bull gear 22 represented by a dotted line. Three pinions 23, 24 and 25 drive the bull gear 22. One of the pinions 23 is larger than the other two to provide the highest speed for drilling a pilot hole. For the purpose of illustration, this pinion gear 23 is represented as being of a 2:1 ratio. The remaining two pinion gears are represented as 3:1 ratios.
A cut away side view of the drive system is shown in FIG. 3. Motors 19, 20 and 21 are mounted on and carried by carriage 14. The large pinion gear 23 engages bull gear 22 to provide high speed drilling. Pinion gears 24 and 25 also engage bull gear and provide high torque, slow speed drilling when all three motors are driving the bull gear.
The hydraulic circuit shown in FIG. 4 represents a circuit for the drive system of FIGS. 2 and 3. For slow speed, high torque, valves 26 and 27 are opened. Fluid from variable speed pump 28 is channeled through motors 19, 20 and 21 in parallel, thereby providing slow speed, high torque drive. When a high speed, low torque drive is desired, valves 26 and 27 are closed. This allows all of the fluid from pump 28 to be channeled through motor 19. A slight positive pressure to motors 20 and 21 is provided by charge pump 29 to prevent cavitation. It can be appreciated that various combinations and numbers of motors may be provided without departing from the scope of this invention. For example, x number of motors could be arranged to drive bull gear 22 and the hydraulic circuit could supply fluid to any combination of the motors. An unlimited range of drive speeds and torques are therefore available to insure optimum drilling conditions.
In the previous embodiment, the motors were hydraulically clutched out when they were not being used to drive the rotary drill column. Instead of hydraulically clutching out the motors, mechanical clutching means may be used. Referring now to FIG. 5, an embodiment of this invention is shown with two motors. The two hydraulic motors 30 and 31 are mounted on a carriage 32 for driving a rotary drill string in the manner described in connection with the previous embodiment. Motors 30 and 31 have pinion gears 33 and 34 for engaging the bull gear 35. Motor 30 is mounted in a primary gear box 36 and gear box 36 is slidably positioned on secondary gear box 37. Relative movement of primary gear box 36 is provided by a threaded element 38 positioned in a matching threaded opening in frame element 39. The other end of element 38 is attached to primary gear box 36 and is free to rotate therein. By appropriate rotation of element 38, pinion gear 33 may be engaged with or disengaged from bull gear 35. It can be appreciated that other mechanical means may be used to engage and disengage the pinion gear without departing from the scope of this invention.
Refering now to FIG. 6, a fluid diagram of the embodiment of FIG. 5 is shown. A variable speed pump 40 supplies fluid to motors 30 and 31 in parallel for slow speed, high torque drilling. When high speed drilling is desired, valves 41 and 42 are closed and the entire volume of fluid is available to drive motor 31. As previously explained in connection with FIG. 5, motor 30 may be mechanically disengaged from bull gear 35, therefore, it is not necessary to provide back pressure on motor 30.
Referring now to FIG. 7, a drive system utilizing four electric motors is shown. Four D.C. electric motors 43, 44, 45 and 46 are positioned on a portion of the carriage 47. These motors have pinions 48, 49, 50 and 51 that may be engaged with bull gear 52 in order to drive the rotary drill column. Motors 43, 44, 45 and 46 and their mountings are slidably positioned in carriage 47. Movement of the individual motors within carriage 47 is provided by a series of threaded elements. For example, motor 43 may be moved into engagement with bull gear 52 by adjustment of threaded elements 53 and 54. When high speed, low torque drive is desired, a single motor 43 may be positioned in engagement with bull gear 52 to drive the rotary drill column. When a greater amount of torque is required, one or more of the remaining motors 44, 45 and 46 may be moved into engagement with the bull gear.
The electrical circuit diagram of FIG. 8 illustrates the operation of the drive system shown in FIG. 7. Electrical current may be supplied to the individual motors 43, 44, 45 and 46 from power source 55. Application of current to each individual motor may be controlled by individual switches 56, 57, 58 and 59. When high speed, low torque is required, such as when drilling a pilot hole, a single motor 43 may be moved into engagement with bull gear 52. Switch 56 is closed and bull gear 52 may be driven at high speed using the single motor 43. When high torque, low speed drive is required, all four motors 43, 44, 45 and 46 may be moved into engagement with bull gear 52. Switches 56, 57, 58 and 59 are closed and all four motors drive bull gear 52 to provide high torque drilling. It can be appreciated that other combinations of motor drive may be provided.
Referring now to FIG. 9, an embodiment of this invention is shown including both electric motors 60 and 61 and hydraulic motors 62 and 63. Because of the particular individual characteristics of the two types of motors, the combination of electric and hydraulic motors produces a drive system with a wide range of drilling speeds and torques. The two electric motors 60 and 61 may be positioned to engage bull gear 64. Mechanical means 65, 66, 67 and 68 engage and disengage the pinions 69 and 70 from bull gear 64. The pinions 75 and 76 of hydraulic motors 62 and 63 may be positioned to engage bull gear 64 by adjustment of mechanical clutching means 71, 72, 73 and 74. When high torque, slow speed drive is requred, pinions 69, 70, 75 and 76 are engaged with bull gear 64 by adjustment of the mechanical clutching means. When high speed, low torque drive is desired a single pinion is engaged with bull gear 64 in order to provide drive by a single motor.
It is to be understood that the motor and pinion used to drive bull gear 64 at high speed may be especially adapted for that purpose. For example, pinion gear 69 of electric motor 60 may be larger than the other pinions. When high speed drive is required, all motors are disengaged from bull gear 64 except motor 60. Motor 60 with the large pinion 69 is energized and the drive system operates at high speed. The remaining pinions 70, 75 and 76 may be smaller and therefore capable of producing high torque. When all four motors 60, 61, 62 and 63 are driving bull gear 64, the highest degree of torque is available. It can also be appreciated that the multiplicity of motors are positioned around bull gear 64 in a manner that provides balanced application of power from the motors to bull gear 64 and therefore a more efficient and effective drive system.
This invention relates to the art of earth boring and more particularly to a drive system for earth boring.
Earth boring operations may require a wide range of drilling speeds and torques. For example, it is often necessary to change from one size bit to a bit of another size. Since each size bit operates best at a particular speed and torque, it is desirable to be able to adjust the drive speed and torque rather than drill under less then optimum drilling conditions. Changes in speed and torque may also be required when a new formation is encountered because the character of the formations determines optimum drilling speed and torque requirements. It may be necessary to change drilling speed and torque to avoid undesirable operating conditions such as critical resonant vibrations. Speed and torque adjustments are extremely important when making up or breaking out sections of the drill string. It can be appreciated that a flexible drive system for an earth boring machine will improve and simplify the drilling operation.
The earth boring machine must be simple, reliable and highly flexible and must be able to provide the range of drilling speeds and torques required. In addition, the boring machine should include a fast, simple, and dependable means of changing drilling speeds and torques.
A specialized earth boring machine that must operate under strict environmental conditions and perform a wide range of drilling operations is used for drilling raises between levels of an undergound mine. This type of boring machine is usually referred to as a raise drill, deriving its name from the finished product. A raise drill must meet all the requirements of an earth boring machine plus the requirements of being compact and able to operate reliably in the confines of an underground mine. The raise drill should operate with a minimum of service because of the difficulty of servicing in an underground mine and the loss of valuable drilling time. The raise drill must be adaptable to being moved in the elevators and narrow passageways of the mine. The need for simplicity, reliability, and safety is extremely important and must be provided without reducing the mechanical operation of the machine. When a pilot hole is being drilled, the drive system should operate at high speed and low torque and when the pilot hole is being enlarged by a reaming operation, the drive system should operate at slow speed and high torque. Other variations in speed and torque are required under various drilling conditions.
DESCRIPTION OF THE PRIOR ART
The drive systems of the prior art do not include a flexible drive system that will produce the wide range of drilling speeds and torques required. In general the prior art drive systems are bulky, inefficient and lack the flexibility needed.
A general summary of raise drilling is provided in U.S. Pat. No. 3,220,494 to R. E. Cannon et al., patented Nov. 30, 1965. The "raise" hole is obtained by drilling a relatively small pilot hole down to a lower level of the mine. The pilot bit is removed and a large raise cutter head or raise bit attached. The pilot hole is enlarged to the desired size by rotating and hydraulically raising the large diameter bit along the pilot hole.
One of the prior art drive systems is represented by U.S. Pat. No. 3,446,284 to N. D. Dyer et al., patented May 27, 1969. This drive system includes a hydraulic motor connected to the rotary member by a chain drive. The speed and torque may be varied by changing the size of the chain sprockets interconnecting the hydraulic motor and rotary member. It can be appreciated that this drive system includes a number of disadvantages. Among these disadvantages is the time and difficulty of changing sprockets in order to effect a change in drill speed and torque.
Another of the prior art drive systems is represented by U.S. Pat. No. 3,454,114 to L. B. Poage, patented July 8, 1969. This drive system includes a motor that drives the rotary member through a complex mechanical transmission system. The mechanical transmission is complex and will not provide the changes in speed and torque required to produce optimum drilling. Because of the elaborate gearing means employed the transmission is subject to mechanical failure.
In U.S. Pat. No. 3,460,638 to Millsapps, Jr., patented Aug. 12, 1969, a drive system is shown that includes fluid motors connected to a kelly. The kelly is in turn connected to the drill string. This drive system also lacks the flexibility and simplicity required to produce optimum drilling.
SUMMARY OF THE INVENTION
The present invention provides an improved drive system that is extremely flexible and reliable. The system is compact, dependable and does not include any complex or elaborate planetary or sprocket mechanisms.
This invention provides a simple drive system for producing the range of speeds and torques required in an earth boring operation. The drilling speed and torque may be adjusted by changing the hydraulic and/or electric circuit supplying power to the drive motors. The drive system of this invention will produce high speed, low torque when drilling a pilot hole and high torque, slow speed when enlarging the pilot hole by a reaming operation. The drive system also provides the flexibility required for make up and break out of sections of the drill string as well as assuring that the drilling operation may proceed under optimum speed and torque conditions.
A multiplicity of motors are connected to the drill head and arranged to transmit rotary motion to the drill string. The speed and torque may be adjusted by changing the circuit delivering power to the various motors. This allows a combination of motors to be used that will provide the drive best suited to the drilling operation. All the power may be diverted to a single motor for high speed drilling or the power may be diverted to all of the motors to provide high torque, slow speed drilling.
It is therefore an object of the present invention to provide an earth boring machine with an improved drive system.
It is a further object of this invention to provide an earth boring machine drive system that is flexible and will produce a wide range of drilling speeds and torques.
It is a still further object of this invention to provide an earth boring machine that is compact, reliable and uncomplicated.
It is a still further object of this invention to provide an improved drive system for a raise drill.
It is a still further object of the present invention to provide an earth boring system that will allow the drilling operation to be carried out under optimum conditions.
The above and other objects and advantages will become apparent from a consideration of the following detailed description when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a raise drill including an embodiment of the drive system of this invention.
FIG. 2 shows one embodiment of the drive system of this invention.
FIG. 3 is another view of the embodiment of the invention shown in FIG. 2.
FIG. 4 is a hydraulic circuit of the drive system shown in FIGS. 2 and 3.
FIG. 5 is another embodiment of the present invention.
FIG. 6 is a hydraulic circuit of the embodiment shown in FIG. 5.
FIG. 7 is another embodiment of the drive system of this invention.
FIG. 8 is an electrical circuit diagram of the embodiment of FIG. 7.
FIG. 9 is an embodiment of this invention including both hydraulic and electric motors.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, a raise drill including one embodiment of the drive system of the present invention is shown generally at 10. The raise drill 10 is anchored to the ground by a base element 11. In order to be certain that raise drill 10 is firmly affixed to the ground, a concrete foundation pad may be installed and base element 11 firmly attached thereto. Supports 12 and 12' are attached to base 11 and held in place by braces 13 and 13'.
A carriage 14 is mounted for travel along supports 12 and 12'. Carriage 14 may be moved along support 12 and 12' by means well known in the art such as a double acting hydraulic thrust cylinder 15 connected between carriage 14 and base element 11. Carriage 14 supports drill head 16 and drive system 17. A rotary drill column 18 is connected to drill head 16 and is in position for drilling down. The individual sections of rotary drill column 18 may be attached and removed during the drilling operation according to the system shown in U.S. Pat. No. 3,446,284 to N. D. Dyer et al., patented May 27, 1969.
The drive system 17 rotates drill head 16 and drill column 18 attached thereto. In raise drilling, a small pilot hole is drilled to another level of the mine. The small pilot bit is removed and a larger raise bit attached. The raise bit is then rotated and moved upward to enlarge the pilot hole to the desired size. It can be appreciated that the raise drilling operation requires a wide range of drilling speeds and torques. A high speed, low torque drive is requred when drilling the pilot hole and a slow speed, high torque drive is required during the reaming operation when the pilot hole is being enlarged. The drilling speed and torque may be adjusted to maintain optimum drilling conditions. In addition, changes in speed and torque are required when sections of the drill column are being added or removed and the speed and torque must be adjusted when changes in drilling conditions are encountered. Although the drilling operation has been shown as drilling directly downward, it is to be understood that a similar operation could be performed upward or at various angles to the vertical.
The present invention provides a drive system that includes sufficient flexibility to enable the various drilling operations to be carried out without elaborate planetary gear systems or time consuming gear and sprocket changes. A plurality of motors are connected to the drill head to provide the power for rotating the drill column. Power is applied through various combinations of motors to provide the desired drilling speeds and torques.
Referring now to FIG. 2, one embodiment of the drive system of the present invention is shown in greater detail. A multiplicity of hydraulic motors mounted on the raise drill carriage drive the drill head and rotate the drill column. The speed and torque may be varied by adjusting the ydraulic pressures and flow volumes through each individual motor. In addition, the speed and torque may be adjusted by variations of the hydraulic circuit. For slow speed, high torque drive, the hydraulic circuit supplies the motors in parallel with the flow through each motor adjusted according to the resistance encountered. For high speed, low torque drive, the hydraulic fluid is channeled through a single motor. Three motors 19, 20 and 21 drive the drill head 16 and supply the power to rotate the drill column. For slow speed, high torque the hydraulic fluid is supplied to motors 19, 20 and 21 parallel. When the high speed, low torque drive is required, as when drilling a pilot hole, the hydraulic fluid is channeled through motor 19 only. The drill head 16 includes bull gear 22 represented by a dotted line. Three pinions 23, 24 and 25 drive the bull gear 22. One of the pinions 23 is larger than the other two to provide the highest speed for drilling a pilot hole. For the purpose of illustration, this pinion gear 23 is represented as being of a 2:1 ratio. The remaining two pinion gears are represented as 3:1 ratios.
A cut away side view of the drive system is shown in FIG. 3. Motors 19, 20 and 21 are mounted on and carried by carriage 14. The large pinion gear 23 engages bull gear 22 to provide high speed drilling. Pinion gears 24 and 25 also engage bull gear and provide high torque, slow speed drilling when all three motors are driving the bull gear.
The hydraulic circuit shown in FIG. 4 represents a circuit for the drive system of FIGS. 2 and 3. For slow speed, high torque, valves 26 and 27 are opened. Fluid from variable speed pump 28 is channeled through motors 19, 20 and 21 in parallel, thereby providing slow speed, high torque drive. When a high speed, low torque drive is desired, valves 26 and 27 are closed. This allows all of the fluid from pump 28 to be channeled through motor 19. A slight positive pressure to motors 20 and 21 is provided by charge pump 29 to prevent cavitation. It can be appreciated that various combinations and numbers of motors may be provided without departing from the scope of this invention. For example, x number of motors could be arranged to drive bull gear 22 and the hydraulic circuit could supply fluid to any combination of the motors. An unlimited range of drive speeds and torques are therefore available to insure optimum drilling conditions.
In the previous embodiment, the motors were hydraulically clutched out when they were not being used to drive the rotary drill column. Instead of hydraulically clutching out the motors, mechanical clutching means may be used. Referring now to FIG. 5, an embodiment of this invention is shown with two motors. The two hydraulic motors 30 and 31 are mounted on a carriage 32 for driving a rotary drill string in the manner described in connection with the previous embodiment. Motors 30 and 31 have pinion gears 33 and 34 for engaging the bull gear 35. Motor 30 is mounted in a primary gear box 36 and gear box 36 is slidably positioned on secondary gear box 37. Relative movement of primary gear box 36 is provided by a threaded element 38 positioned in a matching threaded opening in frame element 39. The other end of element 38 is attached to primary gear box 36 and is free to rotate therein. By appropriate rotation of element 38, pinion gear 33 may be engaged with or disengaged from bull gear 35. It can be appreciated that other mechanical means may be used to engage and disengage the pinion gear without departing from the scope of this invention.
Refering now to FIG. 6, a fluid diagram of the embodiment of FIG. 5 is shown. A variable speed pump 40 supplies fluid to motors 30 and 31 in parallel for slow speed, high torque drilling. When high speed drilling is desired, valves 41 and 42 are closed and the entire volume of fluid is available to drive motor 31. As previously explained in connection with FIG. 5, motor 30 may be mechanically disengaged from bull gear 35, therefore, it is not necessary to provide back pressure on motor 30.
Referring now to FIG. 7, a drive system utilizing four electric motors is shown. Four D.C. electric motors 43, 44, 45 and 46 are positioned on a portion of the carriage 47. These motors have pinions 48, 49, 50 and 51 that may be engaged with bull gear 52 in order to drive the rotary drill column. Motors 43, 44, 45 and 46 and their mountings are slidably positioned in carriage 47. Movement of the individual motors within carriage 47 is provided by a series of threaded elements. For example, motor 43 may be moved into engagement with bull gear 52 by adjustment of threaded elements 53 and 54. When high speed, low torque drive is desired, a single motor 43 may be positioned in engagement with bull gear 52 to drive the rotary drill column. When a greater amount of torque is required, one or more of the remaining motors 44, 45 and 46 may be moved into engagement with the bull gear.
The electrical circuit diagram of FIG. 8 illustrates the operation of the drive system shown in FIG. 7. Electrical current may be supplied to the individual motors 43, 44, 45 and 46 from power source 55. Application of current to each individual motor may be controlled by individual switches 56, 57, 58 and 59. When high speed, low torque is required, such as when drilling a pilot hole, a single motor 43 may be moved into engagement with bull gear 52. Switch 56 is closed and bull gear 52 may be driven at high speed using the single motor 43. When high torque, low speed drive is required, all four motors 43, 44, 45 and 46 may be moved into engagement with bull gear 52. Switches 56, 57, 58 and 59 are closed and all four motors drive bull gear 52 to provide high torque drilling. It can be appreciated that other combinations of motor drive may be provided.
Referring now to FIG. 9, an embodiment of this invention is shown including both electric motors 60 and 61 and hydraulic motors 62 and 63. Because of the particular individual characteristics of the two types of motors, the combination of electric and hydraulic motors produces a drive system with a wide range of drilling speeds and torques. The two electric motors 60 and 61 may be positioned to engage bull gear 64. Mechanical means 65, 66, 67 and 68 engage and disengage the pinions 69 and 70 from bull gear 64. The pinions 75 and 76 of hydraulic motors 62 and 63 may be positioned to engage bull gear 64 by adjustment of mechanical clutching means 71, 72, 73 and 74. When high torque, slow speed drive is requred, pinions 69, 70, 75 and 76 are engaged with bull gear 64 by adjustment of the mechanical clutching means. When high speed, low torque drive is desired a single pinion is engaged with bull gear 64 in order to provide drive by a single motor.
It is to be understood that the motor and pinion used to drive bull gear 64 at high speed may be especially adapted for that purpose. For example, pinion gear 69 of electric motor 60 may be larger than the other pinions. When high speed drive is required, all motors are disengaged from bull gear 64 except motor 60. Motor 60 with the large pinion 69 is energized and the drive system operates at high speed. The remaining pinions 70, 75 and 76 may be smaller and therefore capable of producing high torque. When all four motors 60, 61, 62 and 63 are driving bull gear 64, the highest degree of torque is available. It can also be appreciated that the multiplicity of motors are positioned around bull gear 64 in a manner that provides balanced application of power from the motors to bull gear 64 and therefore a more efficient and effective drive system.