Electricity: motive power systems – Linear-movement motors
Patent
1991-06-10
1993-03-23
Shoop, Jr., William M.
Electricity: motive power systems
Linear-movement motors
318119, 310 14, 417334, 166 664, F04B 1704, H02K 4102
Patent
active
051967707
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a drive device for imparting vertical stepwise motion at substantially constant power to a load, in particular for actuating a vertical reciprocating pump such as that generally disposed at the bottom of a well for extracting oil or water.
BACKGROUND OF THE INVENTION
Such pumping installations usually comprise a piston pump which is lowered inside the well to a specified depth. Its cylinder is securely fixed to the casing of the well while its piston is free to move and is connected to the actuator unit situated on the surface (ground or off-shore platform) by a string of pumping rods constituted by sections that are easily connected end to end or disconnected. The piston generally has non-return valves, and its stroke and frequency are a function of the flow rate of the well.
In all prior wells so far fitted with pumping units, the prime mover is rotary (thermal or electrical). Motion is then transformed either mechanically (nodding beams) or else hydraulically (pump units having actuators). The drive system connecting the prime mover to the string of rods includes members that need to be maintained and adjusted, thus requiring on-site maintenance during extraction, and under current operating conditions the cost of such maintenance is becoming an ever greater burden, particularly in the oil industry.
SUMMARY OF THE INVENTION
The present invention seeks to reduce the fraction of extraction costs represented by such maintenance to as little as possible by simplifying the system for transmitting and transforming motion from the power source to the string of rods.
To this end, the present invention provides a vertically reciprocating and substantially constant power drive unit for raising a load step by step, the drive unit comprising a linear electric motor whose field inductor and whose armature are constituted by two coaxial cylindrical parts, one of which is coupled to a support for the load to be moved and is movable relative to a stationary structure, and further comprising a balancing device exerting a force on the moving equipment constituted by the support for the load and the part of the motor which is coupled thereto, which force is equal and opposite to the sum of the weight of the moving equipment plus one-half the weight of the load.
In a first embodiment, the inductor is fixed relative to the structure, with the armature being made around a moving actuator cylinder constituting a part of the balancing device.
In a variant of this first embodiment, the armature is implemented around a central cylindrical part coupled to the load support, while the balancing device is constituted by at least one actuator parallel to the axis of the armature and coupled between the inductor and the armature.
In a second embodiment, the inductor and the armature are both movable relative to the stationary structure and they are mechanically coupled to each other by at least one flexible suspension link for suspending each of them from the structure, the inductor constituting a part of the balancing device.
The description given below of embodiments of the invention provides better understanding and shows up secondary characteristics and advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference is made to the accompanying drawings, in which:
FIG. 1 is a diagram showing the general dispositions of a downhole pump fitted with a drive unit of the invention;
FIG. 2 is an axial section view through a first embodiment of the drive unit of the invention;
FIG. 3 is an axial section view of a variant of the FIG. 2 embodiment; and
FIG. 4 is an axial section view of a second embodiment of the drive unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a pumping installation for extracting fluid (oil, water, . . .) from an underground deposit and present at the bottom of a well 1. In conventional manner, this installation comprises a downhole pump 2 including a piston 3 (with non-return valves) and a cylinder 4 inside which the piston is driven with reciprocating motion by a str
REFERENCES:
patent: 2122888 (1934-10-01), McLeer
patent: 3681629 (1971-04-01), Drye
patent: 4249867 (1979-05-01), Cunningham
patent: 4281263 (1981-07-01), Virolleau et al.
patent: 4402386 (1983-09-01), Ficheux et al.
patent: 4562385 (1985-12-01), Rabson
patent: 4687054 (1985-03-01), Russell et al.
patent: 4924675 (1990-01-01), Higham et al.
Ayasse Jean-Bernard
Champs Paul
Chardonneau Joel
Maupu Jean-Louis
Cabeca John W.
Marine and Petroleum Equipment
Shoop Jr. William M.
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