Boring or penetrating the earth – With storage means for bit lubricant carried by bit or shaft – With fluid pressure-actuated feed means
Reexamination Certificate
1999-03-24
2001-03-20
Bagnell, David (Department: 3672)
Boring or penetrating the earth
With storage means for bit lubricant carried by bit or shaft
With fluid pressure-actuated feed means
C175S337000, C384S093000, C137S845000, C137S859000
Reexamination Certificate
active
06202766
ABSTRACT:
BACKGROUND OF THE INVENTION
In one aspect, this invention relates to a diaphragm. In another aspect, this invention relates to a valve. In still another aspect, this invention relates to a drill bit containing a lubrication system including a relief valve.
Drill bits employed in the oil and gas industry typically utilize rolling cutters on the lower end of the bit. The rollers are mounted on bearings or bushings which must be supplied with lubricant in order to prevent premature failure.
Lubricant systems which have been devised to provide such a supply of lubricant typically include a pressure compensator system to maintain the lubricant at approximately the same pressure as the borehole fluids surrounding the drill bit. By equalizing the pressure across the lubricant system seals and across the compensator system diaphragm, the risk of system failure is reduced.
Particularly to protect the seals of the lubricant system against increases in pressure from the lubricant side, however, a relief or vent system is still considered very desirable.
It is an object of this invention to provide a valve for venting a drill bit lubricant system.
It is a further object of this invention to provide such a valve which is capable of being manufactured, tested and shipped apart from the bit.
It is another object of this invention to provide a relief valve which can be easily modified to vent at different pressures, or to check flow in one direction if desired.
SUMMARY OF THE INVENTION
In one embodiment of the invention, there is provided a diaphragm element which can be usefully employed in a valve for venting a lubricant system. The diaphragm element has a disk-shaped inner portion and a torus-shaped outer portion. The torus-shaped outer portion is positioned on an outer periphery of the disk-shaped inner portion. The inner portion is well suited for service as a septum to carry a puncture for venting a lubricant system, while the outer portion is well suited for sealing the peripheral area of the diaphragm, against the passage through a valve.
In another embodiment of the invention, there is provided a valve well suited for putting the above described diaphragm element to good use. The valve comprises a valve body which carries a flexible diaphragm element. The valve body has an inner wall surface which defines a passage having a longitudinal axis extending through the valve body. A first wall element extends across the passage and defines a first aperture. A second wall element extends across the passage and defines a second aperture. The second wall element is parallel to, and at a spaced apart distance from, the first wall element. The flexible diaphragm element extends across the passage between the first wall element and the second wall element. The flexible diaphragm element can be as above described, but generally speaking, will have an inner portion and an outer portion with the inner portion having a puncture to provide a pressure relief path. The diaphragm element is positioned parallel to the first wall element and the second wall element and is spaced apart from the first wall element and the second wall element. The outer portion of the diaphragm element is positioned adjacent to the inner wall surface of the valve body and forms a seal between a periphery of the diaphragm element and the inner wall surface of the valve body.
The pressure at which the valve relieves can be varied by adjusting the thickness of the diaphragm element, the size of the puncture, the size of the unsupported area surrounding the puncture, the diameter of the aperture downstream of the puncture, the distance between the diaphragm and the wall element downstream of the diaphragm, and the material from which the diaphragm is constructed. These factors render it a simple manner to provide a two-way relief valve which relieves at a different pressure in each direction. By misaligning the puncture with the aperture on one side, there can be provided a one-way valve which checks flow in the direction of the misaligned aperture and permits flow in the direction away from the misaligned aperture.
In another embodiment of the invention, there is provided a drill bit well suited for putting the above described valve to good use. The drill bit comprises a drill bit body, a bearing, a cutter, and a lubrication system. The drill bit body has at least one downwardly extending leg having a free end. The bearing is mounted on the free end of the at least one downwardly extending leg. The cutter is mounted on the bearing. A reservoir is formed in the drill bit body for storing a supply of lubricant. A lubricant passage is formed in the drill bit body for flow of lubricant from the reservoir to the bearing. A relief port is formed in the drill bit body which connects at least one of the reservoir and the lubricant passage with an outside surface of the drill bit body. A normally-closed relief valve, which can be as described above, is mounted in the relief port to selectively permit fluid flow through the relief port and protect the lubrication system from excessive pressurization.
REFERENCES:
patent: 3151626 (1964-10-01), Everett
patent: 3401719 (1968-09-01), Rosser
patent: 3847234 (1974-11-01), Schumacher
patent: 4727942 (1988-03-01), Galle et al.
patent: 4887675 (1989-12-01), Shotwell
patent: 5072795 (1991-12-01), Delgado et al.
patent: 5441120 (1995-08-01), Dysart
patent: 5490570 (1996-02-01), Millsapps, Jr.
Bagnell David
Casperson John R.
Dougherty Jennifer R.
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