RU2202694C1 - Screw hydraulic machine helical gear rotation mechanism - Google Patents

Abstract

FIELD: oil producing industry. SUBSTANCE: invention relates to helical gear rotation mechanisms of screw downhole motors, screw downhole motors, screw pumps and general-purpose screw hydraulic motors. Cycloidal profiles of one half rotor tooth and one half of stator tooth in end face section are described by equidistant curve of curtate cycloid, and corrected profiles of other half of rotor tooth and other half of stator tooth in end face section are obtained as envelopes of reference profile of conjugate rack formed by conjugation of arcs of circumferences at running over reference profiles without slipping along corresponding diameters. Radius of one of circumferences forming reference profile is equal to radius of equidistant curve, and radius of other circumference is defined by mathematical expression. Invention improved performance characteristics and reliability of mechanism and increases its service life, making it possible to assemble working members without selection and to manufacture rotor and die core by one tool. EFFECT: improved reliability and increased service life. 7 dwg

Description

 The invention relates to gerotor mechanisms of downhole screw motors for drilling oil and gas wells, to screw pumps for oil production and pumping liquids, as well as to general-purpose screw hydraulic motors.

 Known multi-helical screw gerotor mechanism of a downhole motor comprising a stator with internal helical teeth made of an elastic material, for example rubber, and a rotor with external helical teeth, the number of which is one less than the number of stator teeth, and the rotor axis is offset from the stator axis by an amount the eccentricity equal to half the radial height of the teeth, the profiles of the outer teeth of the rotor and the internal teeth of the stator in the end section are mutually bent, and the screw bev rotor and stator are proportional to numbers of their teeth [1].

In the known construction, the stator and rotor tooth profiles in the end section are made as envelopes of the general initial contour of the cycloidal rack, outlined by the equidistant of the shortened cycloid. Moreover, in the end section, the thickness C _t of the stator tooth along the average diameter D _{cp of the} teeth and the circumferential pitch S _{t of} these teeth are related by the ratio C _t / S _t = 0.45-0.65, and the thickness C _N of the stator tooth along the average diameter D _cp teeth in a section perpendicular to the direction of the helix of the stator tooth and the radial height h of the stator tooth are connected by the ratio C _N / h≥1.75.

 A disadvantage of the known gerotor mechanism is that the total diametrical interference in the mechanism is distributed unevenly across the stator teeth: the deformation of the protrusion of the stator tooth is much larger than the deformation of its cavity. As a result of this, the calculated kinematics of the gerotor mechanism is violated, wear on the tops of the teeth of the rotor and stator increases, and the resource of the gerotor mechanism decreases.

Closest to the claimed invention is a gerotor mechanism comprising a stator with internal helical teeth made of an elastic material, for example, rubber, and a rotor with external helical teeth, the number of which is one less than the number of stator teeth, and the rotor axis is offset from the stator axis by the amount of eccentricity equal to half the radial height of the teeth, the moves of the helical teeth of the rotor and stator are proportional to the number of their teeth. The stator teeth profile in the end section is made as the envelope of the initial contour of the cycloidal rack, outlined by an equidistant with a radius R _{C1 of the} shortened cycloid, and the profile of the teeth of the rotor in the end section is made as the envelope of the other initial circuit of the cycloidal rack with the equidistant radius of R _C2 , made more than R _C1 or by the connected relation R _c2 = R _c1 + (0.1 ... 0.5) E, where E is the radius of the generating circle equal to the eccentricity [2].

Another variant of the known invention is also the implementation of the gerotor mechanism in such a way that the profile of the stator teeth in the end section is made as the envelope of the initial contour of the cycloidal rack, outlined by an equidistant curve with a radius R _{c1 of a} shortened cycloid, and the profile of the teeth of the rotor in the end section is outlined by conjugate arcs of circles, moreover, the rotor tooth projection outlined arc of radius R _B, greater than the radius of the stator equidistant R _c1, or coupled with the relation _{R c2 + R c1 (0,1 0,5} ) E, and the rotor tooth profile depressions outlined dy th radius R _v, depending on the number of rotor teeth, its outer diameter and the eccentricity [2].

 However, these versions of the gerotor mechanisms require selective assembly of working pairs due to the need to select the rotor and stator by radial interference. In addition, when working due to the occurrence of lateral interference evenly distributed during convex-concave contact of the rotor tooth with the cavity of the stator tooth, increased wear of the lateral sides of the elastically elastic stator teeth appears; due to the presence of radial and lateral interference in the engagement, friction forces arise in the contact zones of the teeth, creating resistance moments that impede the rotation of the rotor around its axis and its planetary motion, which impairs the energy characteristics of the mechanism. Due to the fact that the initial contours of the tool rails of the rotor and the stator are different, the possibility of manufacturing the rotor and the core of the stator mold with one tool is excluded.

 The technical problem to which the claimed invention is directed is to improve the energy characteristics of the gerotor mechanism of a screw hydraulic machine when hydraulic power is supplied to it and the pressure drop occurs in the working bodies, increase its life and reduce hydromechanical losses due to the formation of a one-sided lateral interference in the gearing, to improve seals along the contact lines in the area of the poles of engagement and reduce contact loads in the area of maximum sliding speeds.

 Another technical task is to increase the manufacturability of production and reduce the cost of the gerotor mechanism by eliminating the selective selection of working pairs by radial interference, as well as by making it possible to manufacture the rotor and core of the stator mold with one tool.

The essence of the technical solution lies in the fact that in the gerotor mechanism of a screw hydraulic machine containing a stator with internal helical teeth made of elastic material, for example rubber, a rotor with external helical teeth, the number of which is one less than the number of stator teeth, and the strokes of the stator helix and the rotor are proportional to the number of their teeth, the rotor axis is offset relative to the stator axis by an eccentricity equal to half the radial height of the teeth, according to the invention cycloidal pros whether one half of the rotor tooth and one half of the stator tooth in the end section were obtained as envelopes of the initial contour of the tool rail outlined by an equidistant shortened cycloid with an equidistant radius r _c , and the corrected profiles of the other half of the rotor tooth and the other half of the stator tooth in the end section were obtained as envelopes of the original the contour of the tool rail formed by the conjugation of circular arcs when running the original contours without sliding along the corresponding tool diameters, the radius is one of the circles forming the initial contour forming corrected profile is radially equidistant r _p, the radius of the other is determined by the expression r _in = (πr) ² / (4a) + ar, the coordinates of the starting points of the contour forming the corrected profile, defined by the expressions: X _n = r _c (1-cosΨ _n ), Y _n = πr-r _c sinΨ _n , X _m = r _in (cosΨ _m -1) + 2a, Y _m = r _in sinΨ _m , the profile angle at current points is defined by the expressions α _pt = (π / 2) -Ψ _n , α _pt = (π / 2) -Ψ _m , where Ψ _n = 0 ... Ψ _a , Ψ _m = 0 ... Ψ _a are the central angles of the current points with the selected discreteness in areas of the original contour with radii r _c and r _in, respectively, Ψ _a = arcsin (πr / (r _c + r _in )) is the central angle of the mating circles at the mating point, and is the radius of the generating circle, r is the radius of the rolling circle, and the corrected profile of the rotor tooth is in engagement with the cycloidal profile of the stator tooth, and the cycloidal profile of the rotor tooth engages in engagement with the corrected stator tooth profile and form a lateral interference in engagement.

 When these ratios are fulfilled for the initial contour of the tool rail and when contact is made in the engagement of the corrected profile of the rotor tooth with the cycloidal profile of the stator tooth, a one-sided lateral interference is ensured, due to which reliable sealing along the contact lines is achieved when hydraulic power is supplied to the hydraulic machine, appears the possibility of reducing radial interference in engagement and assembly of working pairs without selective selection. The moment of resistance forces decreases due to a decrease in radial interference and contact loads in areas as far as possible from the mesh pole, i.e. in the zone of maximum sliding speeds, it is possible to manufacture rotors and mold cores with one tool.

Figure 1 shows a longitudinal section of the gerotor mechanism of a helical downhole hydraulic machine; in FIG. 2 shows a cross section of the gerotor mechanism along line AA; figure 3 shows a diagram of the formation of the initial contour of the tool rail, one part of which is described by the equidistant of a shortened cycloid, and the other is obtained by pairing arcs of circles with radii r _c and r _in ; figure 4 shows the formation of the profile of the rotor of the gerotor mechanism from the original contour of the tool rail; figure 5 shows the formation of the stator profile from the original contour of the tool rail; in FIG. 6 shows a part of the cross-section of the gerotor mechanism along line AA in the area of convex-concave contact of the rotor tooth with the cavity of the stator tooth on an enlarged scale; 7 shows a part of the cross-section of the gerotor mechanism along the line AA in the area of convex-convex contact of the rotor tooth with the protrusion of the stator tooth on an enlarged scale.

The gerotor mechanism of a downhole screw hydraulic machine, see FIGS. 1, 2, comprises a stator 1 with internal helical teeth 2, a rotor 3 with external helical teeth 4, the number of which is one less than the number of internal helical teeth 2 of stator 1. Internal helical teeth 2 of stator 1 made of an elastic material, for example rubber, vulcanized to the inner surface of the core 5 of the stator 1. The axis O ₁ -O _{1 of the} stator is offset relative to the axis O ₂ -O _{2 of the} rotor by an eccentricity E equal to half the radial height h of teeth 2 and 4 or the radius but about zvodyaschey circumference. The working centroid (initial circumference) of the stator 1 of radius c = Ez ₁ touches the working centroid (initial circumference) of the rotor 2 of radius b = Ez ₂ in the pole of engagement P, see figure 2. The moves of the helical lines T ₁ and T _{2 of the} teeth 2 and 4, respectively, of the stator 1 and rotor 3, see FIG. 1 are proportional to the numbers of their teeth z ₁ and z ₂ . Moreover, the rotor and stator are assembled in such a way that the portion of the cycloidal profile of the tooth 4 of the rotor 3 is in contact with the portion of the corrected profile of the tooth 2 of the stator 1 (see figure 2).

соответственно,
где
φ_d2 = 2((Y_n(m)-(x₂+X_n(m))ctgα_pt)/d_w2), φ_d1 = 2((Y_n(m)-(x₁+X_n(m))ctgα_pt)/d_w1) -
углы поворота подвижной системы координат, связанной с инструментальной рейкой относительно неподвижной системы координат, связанной с соответствующей инструментальной окружностью, см. фиг.4 и 5. При этом для совпадения начала координат подвижной системы с осью Х_d ординаты текущих точек исходного профиля определены выражениями Y_n = πr-r_цsinΨ_n; Y_m = r_вsinΨ_m.
Выполнение исходного контура 7 инструментальной рейки согласно заявленному изобретению и сборка ротора и статора таким образом, что участок циклоидального профиля зуба 4 ротора 3 контактирует с участком корригированного профиля зуба 2 статора 1, позволяют:
- получить в зацеплении боковой натяг Δ, см. фиг.6, обеспечивающий надежное уплотнение по контактным линиям и возможность уменьшения радиального натяга;
- уменьшить силы трения в зоне максимальных скоростей скольжения за счет изменения геометрии рабочих органов, см. фиг.7, и возможности уменьшения радиального натяга.An essential feature of the initial contour of the tool rail of the gerotor mechanism according to the invention is that it consists of two sections, see figure 3:
- a shortened cycloid outlined by an equidistant;
- conjugated arcs of circles, the radius of one of which is radially equidistant r _p, the radius of the other: r _in = (πr) ² / (4a) + ar, the coordinates of the current points defined by the expressions X _n = r _n (1-cosΨ _n), Y _n = πr + r _q sinΨ _n, X _m = r _{a (cosΨ m -1) + 2a,} Y m = 2πr-r _in sinΨ _m, where Ψ _n = 0 ... Ψ _a, Ψ _m = 0 .. .Ψ _a with the chosen discreteness, Ψ _a = arcsin (πr / (r _Ц + r _в )). The part of the contour formed by arcs of circles has a length and a height equal to the length and height of the section outlined by the equidistant of the shortened cycloid, i.e. πr and 2a, respectively. In this case, the profile angle of the initial contour conjugated by arcs of circles is defined by the expressions α _pt = (π / 2) -Ψ _n or α _pt = (π / 2) -Ψ _m .
The formation profile of the rotor 3 and stator 1 in the end section is shown in FIG. 4 and 5: the tooth profile 4 and 2 is formed by rolling the tool straight line 6 and the initial contour 7 associated with it without sliding along the corresponding tool circles. The radius of the instrumental circle 8 of the rotor 3 is equal to r _w2 = rz ₂ ; the radius of the instrumental circle 9 of the stator 1 is equal to r _w1 = rz ₁ . To perform the specified diameters of the rotor 3 and stator 1 along the protrusions of the teeth 4 and the troughs of the teeth 2, bias values x ₁ and x _{2 of the} initial stator and rotor circuits are set, respectively, see Figs. 4 and 5. The end corrected profile of the rotor 3 and stator 1 is defined by the expressions

respectively,
Where
φ _d2 = 2 ((Y _{n (m)} - (x ₂ + X _{n (m)} ) ctgα _pt ) / d _w2 ), φ _d1 = 2 ((Y _{n (m)} - (x ₁ + X _{n (m )} ) ctgα _pt ) / d _w1 ) -
the rotation angles of the movable coordinate system associated with the tool rail relative to the stationary coordinate system associated with the corresponding instrumental circle, see Figs. 4 and 5. Moreover, for the origin of the coordinates of the movable system to coincide with the X _d axis, the ordinates of the current points of the original profile are defined by the expressions Y _n = πr-r _c sinΨ _n ; Y _m = r _in sinΨ _m .
The implementation of the initial contour 7 of the instrument rails according to the claimed invention and the assembly of the rotor and stator in such a way that the section of the cycloidal profile of the tooth 4 of the rotor 3 is in contact with the section of the corrected profile of the tooth 2 of the stator 1, allows:
- get in the engagement of the lateral interference Δ, see Fig.6, providing reliable sealing along the contact lines and the possibility of reducing radial interference;
- reduce friction in the zone of maximum sliding speeds due to changes in the geometry of the working bodies, see Fig.7, and the possibility of reducing radial interference.

Gerotor mechanism downhole hydraulic machine operates as follows. When using the gerotor mechanism in a downhole motor, flushing fluid is supplied to the upper part of the gerotor mechanism through a drill pipe string (not shown in FIG.). Under the influence of the pressure drop of the washing liquid, the rotor 3 performs a planetary motion inside the stator 1, rolling around with helical teeth 4 along the helical teeth 2 of the stator 1, see Fig. 1, 2. In this case, the axis O _{2 of the} rotor 3 rotates around the axis O _{1 of the} stator 1 a circle of radius E, and the rotor 3 itself rotates around its axis O ₂ in the direction opposite to the direction of planetary motion, see figure 2.

Kinematically, the movement of the rotor 3 relative to the stator 1 is determined by rolling without sliding the centroid of the rotor 3 of radius b = Ez ₂ along the centroid of the stator 1 of radius c = Ez ₁ with an instantaneous center of rotation of the rotor 3 located at the point of contact of the centroid - pole P of the mesh, see figure 2 . In the area of the engagement pole P, the high and low pressure cavities are separated along the contact lines, while the corrected tooth profile 4 of the rotor 3 is in contact with the cycloidal profile of tooth 2 of the stator 1, and the cycloidal profile of tooth 4 of the rotor 3 is in contact with the corrected profile of tooth 2 the stator 1 and form a lateral interference Δ, which provides reliable sealing between the cavities of high and low pressures, which helps to reduce leakage of the working fluid and, as a result, increase energy characteristics of the gerotor mechanism (power and efficiency).

 In addition, by reducing radial interference and reducing contact loads in the zone as far as possible from the engagement pole, where the sliding speeds are maximum, see Fig. 7 (imaginary section of the cycloidal profile), the moment of resistance forces and wear of the tips of the teeth of stator 2 and 4 are reduced 1 and rotor 3, which also helps to increase the energy characteristics of the gerotor mechanism and its wear resistance.

 The planetary rotation of the rotor 3 is transmitted to the shaft of the support unit and the associated rock cutting tool (not shown in Fig.).

 When using the gerotor mechanism in screw pumps, the rotor 3 is driven into rotation and, rolling around the teeth 2 of the stator 1, converts the mechanical energy of rotation into hydraulic energy of the fluid flow. The kinematics of motion of the rotor 3 of a screw pump and the benefits obtained by using the proposed gerotor mechanism are similar to those described above for a screw motor.

Sources of information
1. RU, patent 2165531, cl. F 01 C 1/16, 5/04, E 21 B 4/02, 2000.

 2. RU, patent 2166603, cl. E 21 In 4/02, 2000 is a prototype.

Claims (1)

The gerotor mechanism of a screw hydraulic machine containing a stator with internal helical teeth made of an elastic material, for example, rubber, a rotor with external helical teeth, the number of which is one less than the number of stator teeth, and the strokes of the helical lines of the stator and rotor are proportional to their number of teeth, axis the rotor is offset relative to the axis of the stator by an eccentricity equal to half the radial height of the teeth, characterized in that the cycloidal profiles of one half of the rotor tooth and one half of the tooth ora a face section outlines the curtailed cycloid equidistance with a radius equidistant r _n and correct the profiles of the other half of the rotor teeth and the other half of the stator teeth in end cross section obtained as envelopes tool initial contour slats generated by conjugation of circular arcs, with run-in starting circuits without sliding along the corresponding tool diameter, the radius of one of the circles forming the source circuit, is equal to the radius r _u equidistant, other radius r is defined by the expression _a = (πr) ² / (4α) + -r, the coordinates of the starting points of the contour forming the corrected profile, defined by the expressions
X _n = r _c (1-cosΨ _n );
Y _n = πr-r _c sinΨ _n ;
X _m = r _in (cosΨ _m -1) + 2α;
Y _m = r _in sinΨ _m ,
profile angle at current points is defined by expressions
α _pt = (π / 2) -Ψ _n ;
α _pt = (π / 2) -Ψ _m ,
where Ψ _n = 0 ... Ψ _a , Ψ _m = 0 ... Ψ _a are the central angles of the current points with the selected discreteness in the sections of the original contour with radii r _c and r _in, respectively;
Ψ _a = arcsin (πr / (r _Ц + r _в )) is the central angle of the mating circles at the mating point;
a is the radius of the generating circle;
r is the radius of the rolling circle,
while the corrected profile of the rotor tooth is engaged with the cycloidal profile of the stator tooth, and the cycloidal profile of the rotor tooth is engaged with the corrected profile of the stator tooth and forms a lateral interference.

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