Rotary expansible chamber devices – Vane or abutment comprises rotatable element
Patent
1994-04-15
1995-10-24
Freay, Charles G.
Rotary expansible chamber devices
Vane or abutment comprises rotatable element
F04C 2344
Patent
active
054604966
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a hydraulically or pneumatically driven wing motor especially but not exclusively for use as a drilling tool in the oil, mining or civil engineering industry for directional including horizontal as well as straight hole drilling or as a top drive to drive a "Drill String". Down hole motors as generally used in the oil and mining industries suffer from the disadvantages that they are very long, heavy and expensive to manufacture.
Various hydraulic wing motors have been previously proposed for down-hole applications but have been found to suffer from severe practical deficiencies due to the extremely harsh operating conditions which down-hole motors are subjected to. One important practical problem arises from the fact that although the drilling mud used to drive the motor is supposed to be subject to intensive screening and cleaning procedures after previous use before it is supplied to the motor, in practice, due to the often difficult operating conditions found at drilling sites, the drilling mud often contains significant amount of more or less abrasive contaminants. These can give rise to severe wear on the parts which results in very rapid loss of performance in the motor due to erosion of parts and leakage therearound, and/or to blockage of small diameter passages used to supply pressurised fluid to displace or otherwise actuate various components of the wing motors, or blockage of small clearances around moving components used for various purposes such as biasing the wing means towards displaced positions thereof.
Another problem that arises with wing motors is that of resistance to retraction of the cyclically displacable wing means as they traverse the radially extending walls means, the existence and significance of which has not previously been recognised and understood. This resistance can give rise to one or more of vibration, unscrewing of the tool from the motor, reduced efficiency, increased wear etc.
Yet another problem that can arise in such motors which use wing means in the form of rollers, is relatively high friction between the rollers and the rotor which require high working fluid pressures to overcome in order to rotate the rotor.
As may be seen from e.g. FIG. 5 of WO90/09510, FIG. 2 of FR-A-2184342, and FIGS. 1 and 2 of GB 1443674, retractable wing means have conventionally been mounted in substantially parallel sided slots of recesses. As shown in WO90/09510 these would most simply extend radially of the rotor. In accordance with GB1443674 (and as also recognized by the present inventor), if such a generally parallel sided slot is inclined relative to a radial plane or orientation, to lean into the direction of rotation (at its open, radially outward, end), then the trailing-side wall of the slot will enclose a less acute angle with the rising wall of the radially inwardly extending wall means thereby reducing resistance to retraction of the wing means as it traverses the rising wall. With such an arrangement, however, we have found that the corresponding inclination of the leading-side wall of the slot or recess results in an increased low pressure side surface area of a wing roller being driven forwards by high pressure fluid thereby resulting in a greater force pressing the wing roller against the casing and leading-side wall of the recess thereby resulting in greater friction.
It is an object of the present invention to avoid or minimize one or more of the above disadvantages.
Thus in one aspect the present invention provides a wing motor of the type suitable for use in down-hole drilling applications, which motor comprises a generally tubular casing and a rotor mounted for rotation within said casing with a chamber therebetween, said casing being provided with angularly spaced apart inlet means and outlet means for ingress of pressurised working fluid from inlet conduit means in said casing into said chamber and egress of said fluid from within said chamber, to outlet conduit means separated from said inlet conduit means by wall means in use of the mot
REFERENCES:
patent: 3447476 (1969-06-01), Farris
patent: 4105377 (1978-08-01), Mayall
patent: 4828468 (1989-05-01), Sipe et al.
Doubenmier John E.
Freay Charles G.
Roe John R. N.
Van Drentham-Susman Hector F.
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