CN118793610A - Oil production pump - Google Patents

Abstract

The invention discloses an oil extraction pump, which comprises a shell, a partition plate, an inner rotor, an outer rotor, a first elliptic gear, a second elliptic gear, a third elliptic gear, a fourth elliptic gear, an upper end cover and a lower end cover, wherein the inner rotor is connected with the partition plate; the partition board is tightly abutted against the inner rotor, and the outer rotor is sleeved on the inner rotor to form a plurality of accommodating cavities; two pairs of same elliptic gears are designed so as to drive the inner rotor and the outer rotor to rotate, speed difference exists, and periodical conversion is performed, so that the volume of a cavity formed between the two rotors is periodically changed, and then a high-pressure cavity and a low-pressure cavity are periodically formed, the oil extraction pump is provided with an oil inlet hole and an oil outlet hole, the low-pressure cavity absorbs oil through the oil inlet hole, and the high-pressure cavity discharges oil through the oil outlet hole; the oil inlet hole and the oil outlet hole are not communicated. The oil extraction pump has the characteristics of large discharge capacity, high output pressure and the like.

Description

Oil production pump

Technical Field

The invention relates to a pump, in particular to an oil production pump.

Background Art

Existing oil pumps mostly use screw pumps or centrifugal pumps. Although these pumps have a relatively simple structure, the output pressure of a single-stage pump is low, the flow rate is small, and the efficiency is very low. If you want to produce oil in a deep well, you must connect many stages in series, and the total length is very long.

Summary of the invention

The purpose of the present invention is to provide an oil production pump in view of the shortcomings of the prior art, wherein all seals of the oil production pump are face seals, the volume is small, the displacement is large, the output pressure is high, and the total length of the same output pressure is much smaller than that of the traditional oil production pump.

The objective of the present invention is achieved through the following technical scheme: an oil production pump, comprising a housing, a partition, an inner rotor, an outer rotor, a first elliptical gear, a second elliptical gear, a third elliptical gear, a fourth elliptical gear, an upper end cover, and a lower end cover; the partition is close to the inner rotor, the outer rotor is sleeved on the inner rotor to form a plurality of cavities; the housing covers the outside of the outer rotor; an upper end cover is provided at the upper end of the housing, and a lower end cover is provided at the lower end; the second elliptical gear is connected to the inner rotor, the fourth elliptical gear is connected to the outer rotor, the first elliptical gear is meshed with the second elliptical gear, the third elliptical gear is meshed with the fourth elliptical gear, and the fourth elliptical gear is meshed with the fourth elliptical gear. The third elliptical gear is meshed with the fourth elliptical gear; when the first elliptical gear and the third elliptical gear are driven, the first elliptical gear and the third elliptical gear respectively push the second elliptical gear and the fourth elliptical gear, thereby driving the inner rotor and the outer rotor to rotate, and there is a speed difference, and periodic conversion, so the volume of the cavity formed between the two rotors changes periodically, and then periodically forms a high-pressure cavity and a low-pressure cavity, the oil production pump is provided with an oil inlet hole and an oil discharge hole, the low-pressure cavity absorbs oil through the oil inlet hole, and the high-pressure cavity discharges oil through the oil discharge hole; the oil inlet hole and the oil discharge hole are not interconnected.

Furthermore, the outer rotor is sleeved on the inner rotor to form a plurality of cavities, including:

The main body of the inner rotor is a cylinder with two symmetrical flanges on it; the main body of the outer rotor is a ring with two symmetrical flanges on the inner surface of the ring; the diameter of the inner surface of the ring is equal to the outer diameter of the two flanges on the inner rotor, and the inner diameter of the two flanges on the inner surface of the ring is equal to the diameter of the cylinder of the inner rotor body; the flanges on the inner rotor and the outer rotor can both cover the oil inlet hole and the oil outlet hole.

Furthermore, the oil production pump is provided with an oil inlet hole and an oil outlet hole, including:

The upper end cover is provided with two symmetrical oil drain holes and two symmetrical oil inlet holes.

Furthermore, the two flanges on the inner rotor are both provided with through holes. When one side of the flange of the inner rotor fits perfectly with one side of the flange of the outer rotor, one end of the through hole is just covered by the upper end cover, and the other end is connected to the low-pressure chamber that has not yet been formed.

Furthermore, the oil production pump is provided with an oil inlet hole and an oil outlet hole, including:

The upper end cover is provided with two symmetrical oil drain holes, the partition is provided with two symmetrical oil inlet holes, and the lower end cover is provided with a plurality of through holes.

Furthermore, the maximum lengths of the oil inlet and the oil outlet holes in the circumferential direction are just covered by the flanges on the inner rotor and the outer rotor.

Furthermore, the shell body is a circular ring, and the diameter of the inner surface of the circular ring is equal to the outer diameter of the outer rotor circular ring.

Furthermore, the first elliptical gear and the third elliptical gear are concentric and fixedly connected, and the other side is connected to the motor shaft.

Further, the tooth profile structural parameters of the first elliptical gear and the third elliptical gear are the same, and the tooth profile structural parameters of the second elliptical gear and the fourth elliptical gear are the same.

Furthermore, the oil production pump is single-stage or multi-stage, and the output of the front-stage pump serves as the input of the rear-stage pump.

Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

1) The present invention utilizes for the first time that the two meshing elliptical gears rotate at different angles and change periodically, and designs two pairs of identical elliptical gears to respectively drive the inner rotor and the outer rotor to rotate, thereby driving the inner rotor and the outer rotor to rotate at different speeds and change periodically, thereby periodically forming a high-pressure chamber and a low-pressure chamber.

2) High pressure and high efficiency, it can pump oil from very deep wells. Because all seals are face seals, it has high pressure and high efficiency, and it can pump oil from very deep wells.

3) Large displacement, because there are two oil inlet holes and two oil discharge holes, the rotor discharges oil twice in one rotation, so the displacement is large;

4) Compared with the traditional oil production pump, the deep well oil production pump provided by the present invention has a higher specific power because of its small size and large displacement;

5) The force is evenly distributed because the two oil inlet holes and the two oil outlet holes are evenly distributed along the circumference, so the force is evenly distributed;

6) Low noise, because the force is evenly distributed, the vibration is small, so the noise is low;

7) Long service life, because all seals are face seals, the force is evenly distributed and the vibration is small, so the service life is long.

8) Since the oil always flows in one direction from bottom to top from the oil inlet to the oil outlet, even if there is a little impurity, it will not affect the operation.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

FIG1 is a schematic diagram of the structure of an oil production pump provided by an embodiment of the present invention;

FIG2 is a top view of FIG1 ;

FIG3 is a schematic diagram of an inner rotor structure provided by an embodiment of the present invention;

FIG4 is a schematic diagram of an outer rotor structure provided by an embodiment of the present invention;

FIG5 is a schematic diagram of an embodiment of the present invention;

FIG6 is another schematic diagram provided by an embodiment of the present invention;

FIG. 7 is a diagram showing an operation principle according to an embodiment of the present invention.

DETAILED DESCRIPTION

Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

In addition, the terms "front", "rear", "up", "down", "left" and "right" are based on the orientation and positional relationship shown in the drawings, and are only for the convenience of describing the present invention, rather than indicating that the device or component referred to must have a specific orientation, and therefore cannot be understood as a limitation on the present invention.

The present invention is described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

An oil production pump of the present invention, as shown in Figures 1 to 4, includes a housing 1, a partition 2, an inner rotor 3, an outer rotor 4, a first elliptical gear 5, a second elliptical gear 6, a third elliptical gear 7, a fourth elliptical gear 8, an upper end cover 9, and a lower end cover 10; the partition 2 is close to the inner rotor 3, and the outer rotor 4 is sleeved on the inner rotor 3 to form a plurality of cavities; the housing 1 covers the outside of the outer rotor 4; an upper end cover 9 is provided at the upper end of the housing 1, and a lower end cover 10 is provided at the lower end; the second elliptical gear 6 is connected to the inner rotor 3, the fourth elliptical gear 8 is connected to the outer rotor 4, and the first elliptical gear 5 is meshed with the second elliptical gear 6 The third elliptical gear 7 is meshed with the fourth elliptical gear 8; when the first elliptical gear 5 and the third elliptical gear 7 are driven, the first elliptical gear 5 and the third elliptical gear 7 push the second elliptical gear 6 and the fourth elliptical gear 8 respectively, thereby driving the inner rotor 3 and the outer rotor 4 to rotate, and there is a speed difference, and the conversion is periodic, so the volume of the cavity formed between the two rotors changes periodically, and then a high-pressure cavity and a low-pressure cavity are periodically formed, and the oil production pump is provided with an oil inlet hole and an oil discharge hole, the low-pressure cavity sucks oil through the oil inlet hole, and the high-pressure cavity discharges oil through the oil discharge hole; the oil inlet hole and the oil discharge hole are not interconnected.

The sealing parts of the present invention are all face seals, and its output pressure is equivalent to that of a plunger pump, so the output pressure of a single-stage pump is extremely high, the length is very short, and the efficiency is very high. It is suitable for deep well oil production pumps. In addition, the elliptical gear rotates one circle and outputs oil twice, which is equivalent to two pumps, so the output flow rate is very large. In addition, compared with the hyperbolic gear pump, the elliptical gear of the present invention is much simpler to process, convenient to design, and has a much smaller total volume. It is easy to implement.

In one embodiment, the first elliptical gear 5 and the third elliptical gear 7 are concentrically and cross-staggered fixedly connected, and when the third elliptical gear 7 is driven to rotate, the first elliptical gear 5 is also driven to rotate.

In one embodiment, the oil production pump is provided with an oil inlet hole and an oil outlet hole, including:

The upper end cover 9 is provided with two symmetrical oil drain holes and two symmetrical oil inlet holes, or

The upper end cover 9 is provided with two symmetrical oil drain holes, the partition plate 2 is provided with two symmetrical oil inlet holes, and the lower end cover 10 is provided with a plurality of through holes.

In one embodiment, when the upper end cover 9 is provided with two symmetrical oil drain holes and two symmetrical oil inlet holes, one oil drain hole and one oil inlet hole form a group, and the distance between the oil drain hole and the oil inlet hole in a group is less than a preset threshold; wherein, the smaller the distance between the oil drain hole and the oil inlet hole in a group, the better.

In one embodiment, referring to FIG. 5 , when there is a gap between the oil inlet hole and the oil drain hole, both flanges on the inner rotor 3 are provided with through holes (not shown in the figure). In the initial state, one end of the through hole is just covered by the upper end cover 9 (that is, the right side of the through hole at this end is aligned with the left side of the oil drain hole), and the other end is communicated with the low-pressure chamber that has not yet been formed (it can also be said that it is opened on the side that is in close contact with the outer rotor 4).

When the oil pump is working, when the left side of the flange on the inner rotor 3 is aligned with the left side of the oil drain hole, there is still some oil in the high-pressure chamber that has not been drained. The through hole set on the flange on the inner rotor 3 connects the high-pressure chamber with the oil drain hole, and the inner rotor 3 continues to rotate (the outer rotor is also rotating at this time, but the rotation speed is obviously lower than the rotation speed of the inner rotor 3). When one side of the inner rotor 3 is tightly attached to one side of the outer rotor 4, the oil in the high-pressure chamber is drained, and one end of the through hole is also covered by the upper end cover 9.

When the left side of the flange on the inner rotor 3 is aligned with the left side of the oil inlet hole, the through hole set on the flange on the inner rotor 3 connects the low-pressure chamber with the oil inlet hole, and the inner rotor 3 continues to rotate (the outer rotor is also rotating at this time, but the rotation speed is obviously greater than the rotation speed of the inner rotor 3), and oil can still enter the low-pressure chamber.

In summary, the through hole solves the problem of incomplete oil drainage and oil failure when rotating to a specific position.

It should be noted that the left and right sides of the flange and the left and right sides of the oil inlet and oil outlet holes are described with reference to the upper half of FIG. 5 .

In one embodiment, when the upper end cover 9 is provided with two symmetrical oil drain holes, the partition plate 2 is provided with two symmetrical oil inlet holes, and the lower end cover 10 is provided with a plurality of through holes, preferably, the maximum length of the oil inlet hole and the oil drain hole in the circumferential direction is just covered by the flanges on the inner rotor 3 and the outer rotor 4; specifically, taking the oil inlet hole and the oil drain hole in one group as an example, in the initial state, the left side of the flange of the inner rotor 3 is just aligned with the left side of the oil drain hole, and is also aligned with the right side of the oil inlet hole; the right side of the flange of the inner rotor 3 is just aligned with the right side of the oil drain hole; the left side of the flange of the outer rotor 4 is just aligned with the left side of the oil inlet hole; the right side of the flange of the outer rotor 4 is just aligned with the right side of the oil drain hole, and is also aligned with the left side of the oil drain hole. The same is true for the other group, which will not be repeated. In this preferred embodiment, there is no problem of incomplete oil drainage and failure to inlet oil when rotating to a specific position, so there is no need to set through holes on the two flanges on the inner rotor 3.

It should be noted that the left and right sides of the flange and the left and right sides of the oil inlet and oil outlet holes are described with reference to the upper half of FIG. 5 .

In one embodiment, the outer rotor 4 is sleeved on the inner rotor 3 to form a plurality of cavities, including:

The main body of the inner rotor 3 is a cylinder with two symmetrical flanges on it; the main body of the outer rotor 4 is a ring with two symmetrical flanges on the inner surface of the ring; the diameter of the inner surface of the ring is equal to the outer diameter of the two flanges on the inner rotor 3, and the inner diameter of the two flanges on the inner surface of the ring is equal to the diameter of the main cylinder of the inner rotor 3.

In one embodiment, the flanges on the inner rotor 3 and the outer rotor 4 have the same shape and can both cover the oil inlet and the oil outlet. Preferably, the maximum length of the oil inlet and the oil outlet in the circumferential direction is just covered by the flanges on the inner rotor 3 and the outer rotor 4.

Referring to FIG5 , it includes two symmetrical oil inlet holes and two symmetrical oil drain holes, the upper one oil inlet hole and the upper one oil drain hole form a group, and the rest form another group; it also includes two symmetrical flanges on the inner rotor 3 and two symmetrical flanges on the outer rotor 4, one flange on the inner rotor 3 and one flange on the outer rotor 4 form a group, and the rest form another group. In the initial state, the two flanges in one group are in close contact; taking the oil inlet hole and the oil drain hole in one group and the two flanges in one group as an example, referring to the upper half of FIG5 , in the initial state (when the oil pump is working, the inner rotor 3 and the outer rotor 4 rotate counterclockwise), the right side of the flange of the outer rotor 4 just covers the right side of the oil inlet hole, and the right side of the flange of the inner rotor 3 just covers the right side of the oil drain hole. When the inner rotor 3 and the outer rotor 4 rotate, the low-pressure chamber formed, namely chamber b, is just connected to the oil inlet hole, and the high-pressure chamber formed, namely chamber a, is just connected to the oil drain hole.

In one embodiment, the main body of the housing 1 is a circular ring, and the diameter of the inner surface of the circular ring is equal to the outer diameter of the circular ring of the outer rotor 4 .

In one embodiment, the first elliptical gear 5 and the third elliptical gear 7 are concentric and fixedly connected, and the other side is connected to the motor shaft.

In one embodiment, the tooth profile structural parameters of the first elliptical gear 5 and the third elliptical gear 7 are the same, and the tooth profile structural parameters of the second elliptical gear 6 and the fourth elliptical gear 8 are the same.

The operation working principle of the present invention is as follows:

FIG5 and FIG6 are schematic diagrams of the principle of the present invention. The motor drives the third elliptical gear 7 and the first elliptical gear 5 to rotate, and the third elliptical gear 7 and the first elliptical gear 5 respectively drive the fourth elliptical gear 8 and the second elliptical gear 6 to rotate, thereby driving the outer rotor 4 and the inner rotor 3 to rotate respectively. FIG2 shows the initial position, and for the sake of clarity, it is represented by the principle diagrams of FIG5 and FIG6. In the first half of the rotation of the two elliptical gears, due to the meshing of the elliptical gears, the rotation speed of the fourth elliptical gear 8 is much greater than the second elliptical gear 6, that is, the rotation speed of the outer rotor 4 is much greater than the inner rotor 3, and the oil in cavity a will be discharged through the oil drain hole. At the same time, due to the high speed of the fourth elliptical gear 8, the outer rotor 4 is driven to rotate at a high speed, and a vacuum is formed in cavity b. As shown in FIG6, cavity b will suck oil from the oil inlet hole. When the first half of the rotation of the two elliptical gears ends, the outer rotor 4 is located at the position of the inner rotor 3 as shown in FIG5, and the inner rotor 3 is located at the position of the outer rotor 4 as shown in FIG5. That is, in the first half of the rotation of the two elliptical gears, the outer rotor 4 rotates from position A to position B, and the inner rotor 3 rotates from position B to position A. In the second half of the rotation of the two elliptical gears, the rotation speeds of the two elliptical gears are reversed, that is, the rotation speeds of the two rotors are reversed, and the rotation speed of the inner rotor 3 is much greater than that of the outer rotor 4. At this time, the role of the second elliptical gear 6 is equivalent to the fourth elliptical gear 8 in the first half of the rotation, that is, the role of the inner rotor 3 is equivalent to the outer rotor 4 in the first half of the rotation, and the role of the fourth elliptical gear 8 is equivalent to the second elliptical gear 6 in the first half of the rotation, that is, the role of the outer rotor 4 is equivalent to the inner rotor 3 in the first half of the rotation. Another round of oil discharge and oil intake is performed. When the two elliptical gears rotate a full circle, the two elliptical gears return to the initial position of Figure 2, that is, the inner and outer outer rotors return to the initial position of Figure 2. This cycle repeats and operates in a cycle.

In order to understand the operating principle of the elliptical gear in more detail, further explanation is given as follows: Its operating principle is shown in Figure 7. In Figure 7, _O1 and _O2 are the rotation centers of the first elliptical gear 5 and the second elliptical gear 6 respectively, ABCDE is an ellipse, and the distance between _O1 and _O2 is set to a constant value of the sum of the distances from a point on the ellipse to the two foci. Ellipse ABCDE is the half elliptical gear corresponding to _O1 , and ellipse ALME is the other half elliptical gear symmetrical to it, together forming an elliptical gear with the rotation center of _O1 . Ellipse CGFG'C' is the half elliptical gear corresponding to the rotation center of _O2 , that is, the conjugate curve gear of elliptical gear ABCDE, and ellipse CHH'C' is the other half elliptical gear symmetrical to it, together forming an elliptical gear with the rotation center of _O2 . When elliptical gear _O1 rotates, it drives elliptical gear _O2 to rotate. When the elliptical gear _O1 rotates counterclockwise from point D to point B, the elliptical gear _O1 rotates 90 degrees, and the elliptical gear _O2 rotates almost counterclockwise from point H to point G, only rotating a small angle. When the elliptical gear _O1 rotates counterclockwise from point B to point L, the elliptical gear _O1 also rotates 90 degrees, and the elliptical gear _O2 rotates almost counterclockwise from point G to point G', rotating a large angle. The cycle repeats in sequence. If two pairs of elliptical gears are designed, one pair of elliptical gears is fixedly connected to the outer rotor, and the other pair of elliptical gears is fixedly connected to the inner rotor. And the two elliptical gears are rotated alternately, so that when one of the elliptical gears rotates from point H to point G, the corresponding elliptical gear rotates from point G to point G'. When the elliptical gear rotates from point G to point G', the corresponding elliptical gear rotates from point G' to point H'. Repeating this cycle, the function of the pump of the present invention can be achieved.

Those skilled in the art will readily appreciate other embodiments of the present application after considering the description and practicing the contents disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application. The description and examples are intended to be exemplary only.

It should be understood that the present application is not limited to the exact construction that has been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof.

Claims (10)

1. The oil extraction pump is characterized by comprising a shell (1), a partition plate (2), an inner rotor (3), an outer rotor (4), a first elliptic gear (5), a second elliptic gear (6), a third elliptic gear (7), a fourth elliptic gear (8), an upper end cover (9) and a lower end cover (10); the partition board (2) is tightly abutted against the inner rotor (3), and the outer rotor (4) is sleeved on the inner rotor (3) to form a plurality of accommodating cavities; the shell (1) is covered outside the outer rotor (4); an upper end cover (9) is arranged at the upper end of the shell (1), and a lower end cover (10) is arranged at the lower end of the shell; the second elliptic gear (6) is connected with the inner rotor (3), the fourth elliptic gear (8) is connected with the outer rotor (4), the first elliptic gear (5) is meshed with the second elliptic gear (6), and the third elliptic gear (7) is meshed with the fourth elliptic gear (8); when the first elliptic gear (5) and the third elliptic gear (7) are driven, the first elliptic gear (5) and the third elliptic gear (7) respectively push the second elliptic gear (6) and the fourth elliptic gear (8), so that the inner rotor (3) and the outer rotor (4) are driven to rotate, speed difference exists, and periodical conversion is carried out, so that the volume of a containing cavity formed between the two rotors is periodically changed, a high-pressure containing cavity and a low-pressure containing cavity are further formed periodically, the oil extraction pump is provided with an oil inlet hole and an oil outlet hole, the low-pressure containing cavity absorbs oil through the oil inlet hole, and the high-pressure containing cavity discharges oil through the oil outlet hole; the oil inlet hole and the oil outlet hole are not communicated.

2. An oil extraction pump according to claim 1, characterized in that the outer rotor (4) is sleeved on the inner rotor (3) to form a plurality of cavities, comprising:

The main body of the inner rotor (3) is a cylinder, and two symmetrical flanges are arranged on the main body; the main body of the outer rotor (4) is a circular ring, and two symmetrical flanges are arranged on the inner surface of the circular ring; the diameter of the inner surface of the circular ring is equal to the outer diameters of two flanges on the inner rotor (3), and the inner diameters of the two flanges on the inner surface of the circular ring are equal to the diameter of a main cylinder of the inner rotor (3); the flanges on the inner rotor (3) and the outer rotor (4) can cover the oil inlet hole and the oil outlet hole.

3. An oil recovery pump according to claim 1, wherein the oil recovery pump is provided with an oil inlet hole and an oil discharge hole, comprising:

The upper end cover (9) is provided with two symmetrical oil drain holes and two symmetrical oil inlet holes.

4. -Oil production pump according to claim 3, characterised in that both flanges on the inner rotor (3) are provided with through holes; when the flange side of the inner rotor (3) is just jointed with the flange side of the outer rotor (4), one end of the through hole is just covered by the upper end cover (9), and the other end is communicated with the low-pressure cavity which is not formed yet.

5. An oil recovery pump according to claim 1, wherein the oil recovery pump is provided with an oil inlet hole and an oil discharge hole, comprising:

the upper end cover (9) is provided with two symmetrical oil drain holes, the partition plate (2) is provided with two symmetrical oil inlet holes, and the lower end cover (10) is provided with a plurality of through holes.

6. An oil recovery pump according to claim 5, characterized in that the maximum length of the oil inlet and outlet holes in the circumferential direction is covered by the flanges on the inner rotor (3) and outer rotor (4).

7. An oil recovery pump according to claim 1, characterized in that the body of the housing (1) is a circular ring, the diameter of the inner face of which is equal to the outer diameter of the circular ring of the outer rotor (4).

8. An oil recovery pump according to claim 1, characterized in that the first elliptical gear (5) and the third elliptical gear (7) are concentric and fixedly connected, the other side being connected to the motor shaft.

9. An oil recovery pump according to claim 1, characterized in that the tooth profile parameters of the first elliptic gear (5) and the third elliptic gear (7) are the same, and the tooth profile parameters of the second elliptic gear (6) and the fourth elliptic gear (8) are the same.

10. An oil recovery pump according to claim 1, characterized in that the oil recovery pump is single-stage or multi-stage, the output of the front stage pump being the input of the rear stage pump.