Transmission System for Drilling Machine

The present disclosure relates to a drilling machine, a transmission system for the drilling machine, and a method of operating the transmission system of the drilling machine.

Drilling machines include a mast that is movably coupled to a frame of the drilling machine. The mast supports one or more drilling components, for example, a drill bit, a hammer, a drill pipe, and the like, to perform drilling operations.

Such drilling machines include a closed-circuit hydrostatic transmission system that operates the one or more drilling components. The hydrostatic transmission system includes one or more drive pumps that are operated by a power source of the drilling machine. The hydrostatic transmission system also includes one or more motors driven by pressure generated by the drive pump and supplied by fluid lines connected between the drive pump and the motor. The motor in turn operates the drilling components. The hydrostatic transmission system further includes a charge circuit. The charge circuit includes a charge pump that replenishes fluid losses occurring in the hydrostatic transmission system, supplies lubrication and cooling flow to one or more components of the hydrostatic transmission system, and also supports pilot pressure for control systems associated with the hydrostatic transmission system. A sudden change in load or torque during an operational event can cause high fluctuations at a low pressure side of the hydrostatic transmission system. Due to such events, a low pressure may be experienced in one of the fluid lines that fluidly connect the drive pump and the motor. Such operational events may include, for example, a break-out event or a tightening event of one or more drill pipes of the drilling machine, a change in a speed of a drill bit, and the like.

In some cases, the pressure at the low pressure side of the hydrostatic transmission system may decrease to as low as 0 bar, which may have a detrimental effect on the drive pump or other components of the hydrostatic transmission system. In some examples, such low pressures may reduce a service life of the components of the hydrostatic transmission system or may cause failure of such components. A size of the charge pump that is currently deployed in the hydrostatic transmission system may not be sufficient to prevent a pressure drop in the low pressure side. Further, increasing a size of the charge pump to overcome the pressure drop may not be feasible. Thus, it is desirable to employ a means of limiting the pressure drop in the fluid lines to ensure continued working of the transmission system and to prevent component failure.

DE4000185A1 describes a hydrostatic gear has a closed circuit and a drive pump with variable displacement, whereby a motor is connected by a first hydraulic lead and a second hydraulic lead to the drive pump. A pressure accumulator is attached by a first non-return valve to the second hydraulic lead by the second non-return valve.

In an aspect of the present disclosure, a transmission system for a drilling machine is provided. The transmission system includes a drive pump. The transmission system also includes a motor driven by the drive pump. The transmission system further includes a first fluid line that fluidly couples the motor with the drive pump. The transmission system includes a second fluid line that fluidly couples the motor with the drive pump. The transmission system also includes a charge pump in fluid communication with the drive pump. The transmission system further includes a fluid charge line that fluidly couples the charge pump with the drive pump. The transmission system includes an accumulator disposed in the fluid charge line and in selective fluid communication with the first fluid line and the second fluid line. In an event of a change in a load on the transmission system, the accumulator is adapted to supply additional fluid towards at least one of the first fluid line and the second fluid line to prevent a reduction in a pressure in at least one of the first fluid line and the second fluid line below a recommended operating level of at least one of the drive pump and the motor.

In another aspect of the present disclosure, a drilling machine is provided. The drilling machine includes a frame. The drilling machine also includes at least one drilling component. The drilling machine further includes a transmission system operatively coupled with the at least one drilling component. The transmission system includes a drive pump. The transmission system also includes a motor driven by the drive pump and adapted to operate the at least one drilling component of the drilling machine. The transmission system further includes a first fluid line that fluidly couples the motor with the drive pump. The transmission system includes a second fluid line that fluidly couples the motor with the drive pump. The transmission system also includes a charge pump in fluid communication with the drive pump. The transmission system further includes a fluid charge line that fluidly couples the charge pump with the drive pump. The transmission system includes an accumulator disposed in the fluid charge line and in selective fluid communication with the first fluid line and the second fluid line. In an event of a change in a load on the transmission system, the accumulator is adapted to supply additional fluid towards at least one of the first fluid line and the second fluid line to prevent a reduction in a pressure in at least one of the first fluid line and the second fluid line below a recommended operating level of at least one of the drive pump and the motor.

In yet another aspect of the present disclosure, a method of operating a transmission system of a drilling machine is provided. The method includes operating a drive pump of the transmission system. The transmission system further includes a charge pump and a fluid charge line that are in fluid communication with the drive pump. The method also includes operating a motor of the transmission system based on operation of the drive pump. The transmission system further includes a first fluid line that fluidly couples the motor with the drive pump and a second fluid line that fluidly couples the motor with the drive pump. The method further includes operating an accumulator of the transmission system to supply additional fluid towards at least one of the first fluid line and the second fluid line to prevent a reduction in a pressure in at least one of the first fluid line and the second fluid line below a recommended operating level of at least one of the drive pump and the motor in an event of a change in a load on the transmission system. The accumulator is disposed in the fluid charge line and in selective fluid communication with the first fluid line and the second fluid line.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Wherever possible, the same reference numbers will be used throughout the drawings to refer to same or like parts.

Referring to, a schematic side view of an exemplary drilling machineis illustrated. The drilling machinemay be used to perform one or more drilling operations, such as, surface drilling, drilling holes, mining blast holes, geothermal wells, and the like. The drilling machinemay include a rotary drilling machine or a down-the-hole drilling machine. In the illustrated example of, the drilling machineis embodied as the rotary drilling machine. The drilling machinemay include a surface rock drill. The drilling machinedefines a first axis “F”. The first axis “F” extends generally in a vertical direction.

As shown in, the drilling machineincludes a frame. The framemay be supported on a ground surface by a transport mechanism, such as, crawler tracks. The crawler tracksmay allow the drilling machineto maneuver on ground surfaces to a desired location for performing drilling operations. Alternatively, the drilling machinemay include wheels instead of the crawler tracks. The frameincludes one or more jacks (not shown herein) for supporting and leveling the drilling machineon the ground surface during drilling operations. In an example, the one or more jacks may lift the drilling machineabove the ground surface along the first axis “F” during drilling operations.

The drilling machinealso includes a machinery. The framemay support the machinery, which may include various components (not shown), such as, a power source(shown in). The power sourcemay include, for example, an engine, a battery system, and/or a fuel cell, that supplies power to operate the drilling machine. The framefurther supports an operator cabin, from which an operator may maneuver and control the drilling machine.

The drilling machineincludes a mast assembly. The mast assemblymay be supported by the frameof the drilling machine. The mast assemblyextends along the first axis “F”. The drilling machinealso includes a mastcoupled to the framethat is movable relative to the frame. Specifically, the mast assemblyincludes the mast.

The drilling machinefurther includes a drill headmovable relative to the mast assembly. The drill headis movable along the first axis “F” and supported on the mast. The drilling machineincludes one or more drilling components(schematically shown in). The one or more drilling componentsinclude a drill pipe, a drill bit, or a hammer, without any limitations. The one or more drilling componentsmay be coupled to the drill headto perform drilling operations.

As shown in, the drilling machineincludes a transmission system. The transmission systemis embodied as a closed-circuit hydrostatic transmission system. The transmission systemis operatively coupled with the one or more drilling components. The transmission systemincludes a drive pump. The drive pumpincludes a bi-directional pump. The drive pumpis a variable displacement hydraulic pump. The drive pumpis driven by the power sourceof the drilling machine. The drive pumpincludes a first portand a second port. The drive pumpmay be controlled, via a flow control valve (not shown herein), to vary a speed of the drive pump.

The transmission systemalso includes a motordriven by the drive pump. The motoroperates the one or more drilling componentsof the drilling machine. The motoris a variable displacement motor. The motorincludes a bi-directional motor that can rotate in a clockwise direction and a counter-clockwise direction. The motorincludes a first portand a second port.

The transmission systemfurther includes a first fluid linethat fluidly couples the motorwith the drive pump. The first fluid lineprovides fluid communication between the first portof the drive pumpand the first portof the motorto rotate the motorin the counter-clockwise direction. The first portof the drive pumpfluidly communicates with the first portof the motorvia the first fluid line.

The transmission systemalso includes a second fluid linethat fluidly couples the motorwith the drive pump. The second fluid lineprovides fluid communication between the second portof the drive pumpand the second portof the motorto rotate the motorin the clockwise direction. Further, the second portof the drive pumpfluidly communicates with the second portof the motorvia the second fluid line. The drive pump, the motor, the first fluid line, and the second fluid linetogether form a main circuit of the transmission system.

The transmission systemalso includes a charge pumpin fluid communication with the drive pump. The charge pumpsupplies fluid to the drive pump. The fluid may be oil, or any other hydraulic fluid. The charge pumpis operated by the power source. The charge pumpmay include a constant displacement pump that operates in a single direction. The charge pumpmay replenish fluid losses happening within the transmission systemdue to internal leakage of rotary components of the transmission system, supply lubrication and cooling flow to the main circuit of the transmission system, and supports pilot pressure for control systems associated with the transmission system. The transmission systemfurther includes a fluid charge linethat fluidly couples the charge pumpwith the drive pump.

The transmission systemfurther includes a first supply linethat provides fluid communication between the first fluid lineand the fluid charge line. The transmission systemfurther includes a first valve. The first valveis disposed upstream of the drive pumpand provides fluid communication between the fluid charge lineand the drive pump. The first valveis disposed in the first supply line. The first valveallows selective fluid flow from the fluid charge linetowards the first fluid linevia the first supply line. Further, the first valveprevents return flow from the first fluid linetowards the fluid charge line. The first valvemay include a check valve.

The transmission systemfurther includes a second supply linethat provides fluid communication between the second fluid lineand the fluid charge line. The transmission systemfurther includes a second valve. The second valveis disposed upstream of the drive pumpand provides fluid communication between the fluid charge lineand the drive pump. The second valveis disposed in the second supply line. The second valveallows selective fluid flow from the fluid charge linetowards the second fluid line. Further, the second valveprevents return flow from the second fluid linetowards the fluid charge line. The second valvemay include a check valve.

Thus, the fluid charge lineis in fluid communication with each of the first supply lineand the second supply line. When a pressure in the fluid charge lineis greater than a pressure in the first or second supply lines,, the fluid can flow through one of the first and second supply lines,, via the respective first or second valves,. The charge pump, the fluid charge line, the first supply line, and the second supply linetogether form a charge circuit.

The transmission systemfurther includes an accumulatordisposed in the fluid charge lineand in selective fluid communication with the first fluid lineand the second fluid line. The accumulatormay include a bladder accumulator, a piston accumulator, or a diaphragm accumulator. In an example, the accumulatoris disposed proximal to the first and second valves,. The accumulatoris in fluid communication with the fluid charge linevia a fluid line.

In an event of a change in a load on the transmission system, the accumulatorsupplies additional fluid towards the first fluid lineor the second fluid lineto prevent a reduction in a pressure in the first fluid lineor the second fluid linebelow a recommended operating level of the drive pumpor the motor. In some examples, upon the supply of the additional fluid by the accumulator, the pressure in the first fluid lineor the second fluid lineis at least equal to a charge pressure in the fluid charge line. In an example, upon the supply of the additional fluid by the accumulator, the pressure in the first fluid lineor the second fluid linemay be equal to a charge pressure at an outlet of the charge pump. In some examples, the recommended operating level may lie between 5 bar and 22 bar. In some examples, the accumulatorsupplies the additional fluid during one or more operational events, such as, a break-out event, a tightening or loosening event of one or more drill pipes of the drilling machine(see), a change in a speed of a drill bit, and the like, without any limitations. The break-out event may include an event in which the drill bit is stuck, and a rotation of the drill bit has stopped but the torque is high, and the drill bit breaks loose causing a whipping action.

In an example, when the motoris rotating in the counter-clockwise direction, the drive pumpsupplies pressurized fluid from the first portof the drive pumpto the first portof the motorvia the first fluid line. In such an example, the first fluid lineis a high pressure line. Further, fluid returns from the second portof the drive pumpto the second portof the motorvia the second fluid line. In such an example, the second fluid lineis a low pressure line.

During one or more operational events, if the pressure in the second fluid linereduces significantly, the accumulatorsupplies the additional fluid to the second fluid lineto prevent the pressure in the second fluid lineto reduce below the recommended operating level. Specifically, during a rapid pressure drop in the second fluid line, the second valvemay open and fluid is transferred from the accumulatorinto the second fluid line, via the second supply lineand the second valve, thereby preventing a pressure drop in the second fluid line.

In another example, when the motoris rotating in the clockwise direction, the drive pumpsupplies pressurized fluid from the second portof the drive pumpto the second portof the motorvia the second fluid line. In such an example, the second fluid lineis a high pressure line. Further, fluid returns from the first portof the drive pumpto the first portof the motorvia the first fluid line. In such an example, the first fluid lineis a low pressure line.

During one or more operational events, if the pressure in the first fluid linereduces significantly, the accumulatorsupplies the additional fluid to the first fluid lineto prevent the pressure in the first fluid lineto reduce below the recommended operating level. Specifically, during a rapid pressure drop in the first fluid line, the first valvemay open and fluid is transferred from the accumulatorinto the first fluid line, via the first supply lineand the first valve, thereby preventing a pressure drop in the first fluid line.

It should be noted that the transmission systemmay further include other components that are not illustrated and explained in this disclosure, for the sake of simplicity. Such components may assist the transmission systemin performing the intended functions in a manner known in the art, as per application requirements.

It is to be understood that individual features shown or described for one embodiment may be combined with individual features shown or described for another embodiment. The above-described implementation does not in any way limit the scope of the present disclosure. Therefore, it is to be understood although some features are shown or described to illustrate the use of the present disclosure in the context of functional segments, such features may be omitted from the scope of the present disclosure without departing from the spirit of the present disclosure as defined in the appended claims.

The present disclosure relates to the transmission systemincluding the accumulator. When the pressure in the first or second fluid lines,reduces due to one or more operational events in the drilling machine, the accumulatorsupplies the additional fluid to the first or second fluid lines,, thereby preventing the pressure in the first or second fluid lines,to reduce below the recommended operating level of the drive pumpor the motor. Such operational events may include, for example, the break-out event or the tightening event of the one or more drill pipes of the drilling machine, the change in the speed of the drill bit, and the like.

The accumulatormay improve an overall performance and a reliability of the transmission system. The accumulatorpresents a simple and a cost-effective technique of maintaining the pressure in the low pressure line within acceptable limits. As the pressure in the low pressure line is prevented from reducing below the recommended operating level of the drive pumpor the motor, a susceptibility of failure of the drive pump, the motor, or other components of the transmission systemmay be prevented. Thus, the accumulatormay prevent a reduction in a service life of the components of the transmission system, and may also reduce cost and efforts associated with replacement or servicing of the components of the transmission system. Further, the teachings of the present disclosure may be implemented on existing drilling machines.

illustrates a flowchart for a methodof operating the transmission systemof the drilling machine. Referring to, at step, the drive pumpof the transmission systemis operated. The transmission systemfurther includes the charge pumpand the fluid charge linethat are in fluid communication with the drive pump. The drive pumpincludes the bi-directional pump. The stepfurther includes operating the drive pumpin any one of the clockwise direction and the counter-clockwise direction.

At step, the motorof the transmission systemis operated based on the operation of the drive pump. The transmission systemfurther includes the first fluid linethat fluidly couples the motorwith the drive pumpand the second fluid linethat fluidly couples the motorwith the drive pump

At step, the accumulatorof the transmission systemis operated to supply the additional fluid towards the first fluid lineor the second fluid lineto prevent the reduction in the pressure in the first fluid lineor the second fluid linebelow the recommended operating level of the drive pumpor the motorin the event of the change in the load on the transmission system. The accumulatoris disposed in the fluid charge lineand in selective fluid communication with the first fluid lineand the second fluid line. Further, upon the supply of the additional fluid by the accumulator, the pressure in the first fluid lineor the second fluid lineis at least equal to the charge pressure in the fluid charge line.

The methodfurther includes a step of at which the motoroperates the one or more drilling componentsof the drilling machinebased on the operation of the motor. The one or more drilling componentsincludes the drill pipe, the drill bit, or the hammer.

It should be noted that one or more steps,,of the methodmay be performed in an order that is different from that explained and illustrated in reference to. Further, one or more of the steps,,may be performed together.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.