FR2609754A1 - MULTIFUNCTION SCREW MOTOR WITHOUT CARDAN SEAL - Google Patents

Abstract

THE INVENTION RELATES TO A BOTTOM SCREW MOTOR IN WHICH THE CARDAN GASKET HAS BEEN REPLACED, AS SHOWN IN FIGURE 1, BY A SECOND SCREW MOTOR HAVING A DIFFERENT NUMBER OF THREADS FROM THE FIRST. THE TWO ROTORS 10 AND 16 ARE LINKED AND TURN WITH THE SAME ECCENTRICITY "E" WITH RESPECT TO THEIR STATORS 8 AND 14. IN THESE CONDITIONS, THE SECOND STATOR 14 TURNS CONCENTRICALLY WITH RESPECT TO THE FIRST STATOR 8 LINKED TO THE ENGINE SHEATH 1 AND CAN THEREFORE DRIVE THE TREPAN WITHOUT CARDAN SEAL. THE TWO ROTORS 10 AND 16 ROTATE BETWEEN TWO STOPS 3 AND 23 AND THE SECOND STATOR 14 IS RADIALLY AND AXIALLY GUIDED BY A SMOOTH BEARING 17 LUBRICATED BY PART OF THE MUD AND BY ROLLER BEARINGS 31, 32 AND 36 TURNING IN THE GREASE .

Description

The present invention relates to a screw motor which can be between

  others, used as background motor in

  drilling oil and gas wells.

  There are already motors of this type whose stator and the rotor constitute a hypocycloidal gear. The stator

  consists of internal helical teeth in

  overmolded tomere in a metal sheath. The rotor is made of hard helical outer teeth with one less thread than the stator. The rotor and the stator form a kinetic couple with a permanent engagement comparable to an internal gear. When the rotor rotates about itself, a cylinder centered on the axis of the stator of radius equal to the eccentricity ge "such that: 2e = D2-Di, D1 and DA being the pitch diameters of the rotor and the stator To drive the rotary bit, the rotor must be connected to it by a double universal joint, which is a delicate part in such an environment, and is cluttering. For this purpose, the number of rotor threads must be increased, since the rotor rotates on itself at a speed inversely proportional to its number of threads for a constant speed of rotation of the rotor axis. relative to the axis of the stator.

  the rotor axis causes harmful vibrations.

  The present invention aims to eliminate the double universal joint by replacing it with a second engine of the

  same type as that described above, ie

  both a rotor and a stator but whose number of nets

  different from the number of rotor and stator threads of the first

  first motor while having the same eccentricity me "of the rotor

compared to the stator.

  By attaching the rotor of the first motor to the rotor of the second motor, a gear train and the stator are created.

  the second engine then turns concentrically

  port to the stator of the first motor and can be attached to the bit without universal joint. We then have more power for the same size. This gear train gives a multiplier permitting to get a couple

  high at low speed of rotation of the trepan.

  More specifically, the invention relates to a motor

  screw consisting of at least two helical gear motors

  the first motor comprising a stator so-

  the lid of the motor shaft in which rotates with an eccentricity "relative to this stator a rotor

  having one less thread than the stator, and a second

  having a rotor having a different number of nets

  the first rotor, attached to it and rotating in a

  stator with the same eccentricity Me ", says the second sta-

  tor being integral with the output shaft of the screw motor and

  concentrically rotating relative to the first stator.

  In the following, the preferred embodiment of the invention is explained in more detail with the aid of drawings in which: FIG. 1 represents a longitudinal section of the motor

screw according to the invention.

  - Figure 2 shows a cross section of the engine

of Figure 1 by line II-II.

  FIG. 3 represents a cross section of the same model.

  Figure 1 through line III-III.

  Referring to Figures 1, 2 and 3, it is noted that the engine comprises from the top: - a fitting 2 provided with a thread to connect to the drill string bringing the drilling mud - a sheath 1 to screw itself on fitting 2

  a stop 3 for positioning the rotors 10 and 16 longitudinally

  tudinalement, pierced with orifices 4 for the passage of the mud and a circular groove 5 in which rolls a ball 7 on which rests the rotor 10. This stop 3

  is kept in contact with the rotor 10 via

  spring 6 - a stator 8 with four elastomer threads overmolded in a sleeve 9 - a rotor 10 with three hard steel threads terminated by a flange II

  a rotor 16 with two threads terminated by a flange 12 attached

  1 to the flange 1il by bolts 13 so that the axes of the rotors are merged - a stator 14 three elastomeric threads overmolded in a sleeve 15 whose lower portion is screwed onto the fitting 26 - a bearing 17 of elastomer overmolded in a sheath 18 having longitudinal grooves 20 and a filter 19 at its upper part - an orifice 25 in the sheath 1 - a stop 23 of hard material reported in the connector 26 and having a circular groove 22 in which rolls a ball 21 - A fitting 26 receiving the stop 23 and pierced with orifices 24 for the passage of the sludge - an output shaft 27 having a shoulder 34 for positioning longitudinally the rotating part of the engine which is screwed to the fitting 26 - a set of bearings 31 , 32 and 35, for maintaining the output shaft radially and longitudinally - a spring 33 for preloading the bearings 31 and 32 - a cylinder assembly 29, piston 28 and spring 30, so

  a set of herringbone joints 37 to maintain the rolls

  in the grease injected through the orifice 36 -a spacer 38 between the two bearings 31 and 32 -a connector 39 to connect the bit The drilling mud arriving through the upper connector 2 drives the rotor 10 in a rotation on it same and in a reverse rotation about the axis of the stator 8 by the

  continuous creation of isolated rooms between them and

  put at different pressures.

  The stator 8 having four threads and the rotor 10 three nets, this one turns on itself when its center

  take three turns around the center of stF tcr 8 with ur-

centricity "e" such that:

  e = D, DI being the primary diameter: tif dL rCotc.

  The rotor 16 has two threads and the stator 14 has three threads the main diameter of the rotor 16 is such that e = iy, = to '/ 6> therefore DX = 2/8 D, This allows the stator 14 to stay centered on the stator 8

  when both rotors turn under the effect of mud.

  The rotor 16 rotates relative to the stator 14 by half a turn

  when its center rotates one turn around the axis of the

  tor 14. This turns in the opposite direction of * turn

  relative to the rotor 16 and thus to the rotor 10 which is attached to it

  ket. The stator 14 thus rotates relative to the stator 8 and on the same axis of: (I'ourour - 1 / 3tour) * Z / - = I / JtoLur The stator 14 is attached to the output shaft by the

  connection 26 and can therefore directly transmit this rotation.

  to the trepan without going through the double universal joint

usual.

  Since the stator 14 is smaller in diameter than the stator, a bearing 17 of the type used on the shaft lines of the ships can be placed on its entire periphery. This bearing 17 is lubricated and cooled by sludge which circulates through grooves. 20. The sludge circulation is obtained by a calibrated orifice in the sheath 1 and its flow is a function of the difference in pressure between the inlet of the second motor and the outside of the sheath. Four limit

  the abrasion of the bearing 17 and avoid the obstruction of the

  25, a filter 19 is placed at the input of the bearing 17.

  The set of rotors 10 and 16 is subjected to a longitudinal thrust 3: 0 which is counterbalanced by a ball stop constituted by the ball 21 and its support 23. At the top, an identical assembly 3 and 7 can limit the longitudinal displacement of the rotors, the abutments being

  held in contact with the rotors by the spring 6.

  The connector 26 is screwed onto the shaft 27 itself screwed onto a wear connector 39 receiving the drill bit. The shaft 27 is provided with a shoulder 34 on which are supported two oblique bearings 31 and 32 which transmit to the body of the engine the thrust due to the weight on the tool and that due to the pressure drop across the engine and the trepan. A spring 33 makes it possible to apply a preload on these rolls. To allow proper operation of the bearings,

  these are placed in fat injected by the ori-

  36. This fat is put in slight overpressure by

  compared to the sludge by a piston 28 sliding in the cy-

  29 and compressed by the spring 30. In the lower part

  a chevron joint of the type used in the heads

  sludge injection, isolates the bearings from the mud

  pool. A roller bearing 35 limits the eccentricity of

  the shaft 27 relative to the sheath 1 for a good function

seal 37.

  Of course, the invention is not limited to only

  described embodiments. Variants can be

  made without departing from the scope of the present invention.

  It is thus possible to modify the number of stator teeth, the type of bearings and abutments as well as joints and their arrangement. (l to -Le5 1st ap inala3xc

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