The present invention relates generally to pressurized fluid driven devices, such as pneumatic tools, and more particularly to a pressurized fluid driven down-hole hammer apparatus and method that provides increased hammering force.
Down-hole hammers, which are also called down-the-hole or DTH hammers, have long been known in the art. Such devices utilize pressurized fluid to actuate a piston housed within the tool. The piston produces axial, percussive forces that destroy rock. The force produced by the piston in a conventional down-hole hammer is proportional to the pressure of the pressurized fluid and the area of the piston acted on by the fluid in the direction of the piston's motion. Thus, the force may be increased by increasing the fluid pressure, by increasing the piston area, or by increasing both. The pressurized fluid is generally air, but other fluids, including but not limited to water, may be used depending on the application.
There are, however, deficiencies associated with conventional down-hole hammers. For example, the maximum force produced by a conventional down-hole hammer is generally limited by the size of the hole to be drilled. More specifically, the size of the hole to be drilled limits the size of the hammer's housing, which in turn limits the area of the piston acted on by the pressurized fluid. In addition, the maximum force of conventional hammers is also limited by the pressure of the working fluid. In some situations it may not be practical, or even possible, to increase the pressure of the working fluid. For example, increasing the pressure would lead to increased energy consumption by the compressor, and thus would increase the overall cost of the drilling operation. Higher pressures may also exceed the hammer's structural design limitations, and thus lead to structural failures or decreased tool life. In other words, even when there are no dimensional constraints, there are generally other constraints that limit the maximum potential force produced by conventional down-hole hammers. Furthermore, it is often difficult to optimize the dimensions, energy consumption, working fluid pressure, and axial forces of conventional down-hole hammers. Thus, there currently exists a need for an improved down-hole hammer that alleviates deficiencies associated with conventional down-hole hammers.
One embodiment of an extra area down-hole hammer apparatus provides a pressure operated actuator that operates in a first and second phase. The pressure operated actuator includes a housing having a pressure source opening for receiving a source of pressure. Further, the pressure operated actuator includes a piston inside the housing such that the piston moves along the inside of the housing. The piston may be positioned in the housing so that a first chamber may be created between one end of the piston and the housing and a second chamber may be created between the other end of the piston and the housing. The pressure operated actuator further includes a first port capable of being in communication with the pressure source opening during the first phase of the pressure operated actuator and a second port capable of being in communication with the pressure source opening during the second phase of the pressure operated actuator. In addition, the pressure operated actuator includes a first extra area chamber between the piston and the housing. Moreover, the pressure source opening and piston are configured in a manner so that in the first phase of the pressure operated actuator, the first port may be in communication with the pressure source opening for receiving the source of pressure and allowing the source of pressure to be provided to the first and first extra area chambers. In the second phase of the pressure operated actuator, the second port may be in communication with the pressure source opening for receiving the source of pressure and allowing the source of pressure to be provided to the second chamber.
Another embodiment provides a down-hole hammer comprising a housing having an inner dimension, and a source opening within the housing for receiving a source of fluid for creating movement in the hammer. In addition, the hammer comprises a piston having an inner dimension, an outer dimension, and a reduced outer dimension. The piston is adapted to fit inside the housing such that the outer dimension of the piston may be movable along and within the inner dimension of the housing. The housing and piston may be generally tubular or cylindrical in shape, but other shapes are feasible and considered within the scope of the invention. Further, the piston comprises a top surface defining a first pressure chamber adjacent a top portion of the housing, and a bottom surface defining a second pressure chamber adjacent a bottom portion of the housing. The hammer also comprises an extra area component positioned between the housing and the piston such that the reduced outer dimension of the piston may be movable along the extra area component, and wherein a surface of the extra area component together with the reduced outer dimension of the piston and the inner dimension of the housing defines an extra area chamber. The piston also comprises: a first port in fluid communication with the source opening, the first port extending between the inner and outer dimensions of the piston; a second port in fluid communication with the first port that extends from the first port along a portion of the length of the piston; and a third port in fluid communication with the second port that extends from the second port toward the outer dimension of the piston and in communication with the extra area chamber. The working fluid may be air, a gas, water or another fluid depending upon the particular application.
Yet another embodiment provides a method of operating a piston-driven, down-hole hammer apparatus. The piston-driven hammer may have a tubular piston with an inner diameter, an outer diameter, and reduced outer diameter. The piston may be movable within a housing that has an inner diameter, and the piston may operate in an upstroke phase and a downstroke phase. During the downstroke phase the method comprises receiving into the piston fluid having a first pressure (or flow rate); providing the received fluid to an area between an upper outer surface of the piston and an upper inner surface of the housing to create a force that drives the piston in a downward motion; and providing the received fluid through porting to an extra area chamber between the reduced outer diameter of the piston and the inner diameter of the housing, the provided fluid in the extra area chamber creating an additional force that drives the piston in a downward motion. During the upstroke phase the method comprises receiving into the piston fluid having a second pressure (or flow rate); and providing the received fluid to an area between a lower outer surface of the piston and a lower inner surface of the housing to create a force that drives the piston in an upward motion.
Thus, provided is an improved down-hole hammer apparatus and method for increasing energy delivered to a piston. This invention comprises adding extra area to devices whose work, velocity and energy transfer may have been limited by the internal dimensions of their housings. The invention may further comprise extra area feed bores in conjunction with an extra area component so that the pressurized fluid may be fed between the annulus that may be articulated between the component and the piston face diameter resulting in increased velocity of the piston. This invention and method may be implemented in an array of different applications and contexts that involve fluid-driven, pistons.
A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein:
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, preferred embodiments are described.
Referring to
An elongated central passage 18 extends through the top subassembly 14 and may be adapted for operatively conducting air or fluid throughout the hammer apparatus 10. Feed tube 24 may be positioned within housing member 16 and may be operatively configured to receive the air or fluid from central passage 18. Feed tube 24 includes apertures 20a, 20b, and 22 at an upper portion of the feed tube 24 and apertures 25a, 25b and 23 at a lower portion of the feed tube 24. In operation, central passage 18 may be configured to deliver compressed air or fluid through apertures 20a and 20b and into feed tube 24.
In addition,
In a conventional hammer apparatus known in the art, the amount of downward or upward force applied to the piston may be limited to the surface area of the chambers formed above and below the piston, respectively. In particular, the force may be equal to pressure (often measured in pounds per square inch) multiplied by the surface area. Thus, the maximum force of conventional hammers is generally limited by the internal diameter of the housing.
The embodiments discussed below provide an increased force to the piston without increasing the diameter of housing 16. According to this improvement, piston 11 may include at least one reduced diameter portion 37 along an external wall of piston 11 to form an annulus between an external wall of piston 11 and an internal wall of housing member 16. An extra area component, for example extra area ring 34, forms a seal between an upper extra area chamber 52 and a lower extra area chamber 32 in the annulus. Extra area ring 34 can be held in place with extra area component fasteners, such as extra area set pins 36. The extra area ring 34 and extra area set pins 36 may comprise, without limitation, metal, composite materials or the like. Alternatively, other sealing means known in the art may be used instead of extra area ring 34 and extra area set pins 36. According to at least one embodiment, the extra area ring 34 and extra area set pins 36 are operatively removable such that the seal may added to, or removed from, housing 16. It is to be understood that the seal provided by the extra area ring 34 and extra area set pins 36 may be provided by other sealing and closure members.
The extra area component may take on alternative forms. For example, the extra area component may be any structure that forms a suitable partition or division between upper extra area chamber 52 and lower extra area chamber 32. For example, the extra area component may be an integral part of the housing member 16. In another embodiment the extra area component may include a shoulder attached to the housing member 16. The extra area component may also be a rib that projects from the inner wall of the housing member 16. In this instance, the rib may be an extra area component that may be integrally connected to the housing member 16 and may function similar to the extra area ring 34.
In addition, the apparatus may utilize multiple extra area components. As an example, some embodiments may include multiple extra area rings 34. In yet another embodiment that includes more than one piston 11, one or more of the pistons 11 may include one or more extra area components, for example, multiple extra area rings 34.The extra area component fasteners may also take on various forms to accomplish fastening, or keeping together, the extra area component. For instance, in one embodiment the extra area component, such as an extra area ring 34, may be fastened using “O” rings. In an alternative embodiment, snap rings may be used. In yet another embodiment, an alternative method or means may be employed for fastening the extra area component.
The extra area ring 34 may include grooves 33 and 35 as shown in
Referring to
The extra area ring 34 may provide a simple and effective assembly and disassembly method. For example, in one embodiment, the ring halves 39 and 40 may be inserted and removed with the piston 11. Moreover, the ring halves 39 and 40 may be joined to form the extra area ring 34 in different ways. For example, in one embodiment, the set pins 36 may be inserted from the outside of the housing 16 and secured with welding. Alternatively, the pins 36 may be secured with set screws or keys. Further, in an alternative embodiment, the ring halves 39 and 40 may be secured by spring loaded pins that extend out from the ring halves 39 and 40 to lock the extra area ring 34 in place. In some embodiments, the spring loaded pins used for securing the ring halves 39 and 40 may be retractable by using an access hole through the cylinder housing 16. In alternative embodiments, the spring loaded pins used for securing the ring halves 39 and 40 may be retractable by using a key system between the piston 11 and the extra area ring 34.
In one embodiment, the extra area ring 34 may have a Total Indicator Reading (“TIR”) of no more than 0.003 inches on the outer circumference and the inner circumference of the ring. In a preferred embodiment, the extra area ring 34 may have a TIR of no more than 0.001 inches on the outer circumference and the inner circumference of the ring. Using an extra area ring with a TIR of no more than 0.001 inches provides an extra area surface that may allow for a single piece hammer piston 11 design that maximizes strength and durability of the piston 11. Further, an extra area ring 34 may provide a very high tolerance fit which may reduce fluid leakage between chambers. Moreover, an extra area ring 34 may provide a consistent radial fit between the piston 11 and extra area surfaces for reduced wear, longer life and higher performance.
There are various methods for fabricating an extra area ring 34. For example, a “cut before machining” fabrication method may be used to form an extra area ring 34 having a TIR within the limits described above. For example, the cut before machining fabrication method may include cutting a disk from a piece of cylindrical bar stock. The disk may be then cut or sawed in half to form two half disks. Then, the two half disks are placed together and a hole or bore is machined in the center of the disks form a ring shape (i.e., similar to a doughnut). The inner circumference and the outer circumference are machined so that, upon completion, the ring will have a concentricity within the TIR limits discussed above. This ring may be used to form an extra area ring 34 by joining both halves of the ring using, for example, extra area pins 36 or various other methods as explained above. As an alternative, the ring may be formed from cylindrical tube stock, rather than cylindrical bar stock. If cylindrical tube stock is used, it will not be necessary to machine the hole or bore in the center of the work piece before machining the inner and outer circumferences. Other methods for fabricating extra area components, such as extra area ring 34, may also be used.
Referring back to
The embodiments may allow for extra area forces to be applied to either or both of the upward and downward strokes of the piston 11. For example,
Referring back to
As illustrated in
The left side of the diagram shown in
Referring to
A method of improving the operating force of a down-hole hammer using the above-described apparatus is also envisioned. According to this method, the operating force may be increased by increasing the area provided to an internal piston by including one or more separated, extra area chambers formed between the piston and an internal wall of the down-hole hammer housing.
For example,
In addition,
Many other modifications and variations of the embodiments discussed above are possible in light of the above teachings. For instance, the improvements of the embodiments may be utilized in any device in which the energy transfer may have been limited by the area of the internal dimension of a cylinder that houses the device. Likewise, the number of chambers of the orientation may be adjusted. Further, various porting configurations are possible.
The specific embodiments discussed herein are merely illustrative, and are not meant to limit the scope of the present invention in any manner. It is therefore to be understood that within the scope of the disclosed concept, the invention may be practiced otherwise than as specifically described. For example, an extra area down-hole apparatus may be provided using a piston apparatus that is different than the hammer apparatus 10 shown in the aforementioned embodiments, while still comporting with the spirit of the invention. For instance, existing hammers may be modified to include an extra area chamber.
This application claims the benefit of U.S. Provisional Application No. 61/423525, filed Dec. 15, 2010, which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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61423525 | Dec 2010 | US |