CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on and claims the priority benefits of China application No. 202110640555.2, filed on Jun. 8, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The present application relates to a downhole motor, in particular to a full-metal anti-high temperature cycloid downhole motor driven by a high temperature drilling fluid.

Description of Related Art

Downhole motors are also called positive displacement motors. At present, downhole motors with mechanical characteristic such as “hard” are only screw motors, which are widely used in the drilling industry. However, screw motors also have the following problems during actual use: (1) a stator in the conventional screw motor is made of rubber and cannot be used under high temperature conditions, fore example the downhole temperature is ≥180° C.; (2) a full-metal screw replaces the rubber stator with a metal stator, but the current processing level cannot guarantee the processing accuracy; (3) the screw motor is used for spiral distribution, and for the helix, the lead must be 2-3 times the conventional lead to achieve the flow distribution driving effect, which causes that the screw motor is generally too long; (4) the screw motor has an interference fit between the stator and the rotor, the drilling fluid containing impurities during downhole drilling can easily cause jam and abrasion between the stator and rotor, reducing the service life of the motor.

Regarding the above-mentioned related technologies, the traditional downhole motor has the defects of being easy to jam, easy to wear and not resistant to high temperature during downhole drilling.

SUMMARY

In order to improve the problems of being easy to jam, easy to wear and not resistant to high temperature between a stator and a rotor, the present application provides a full-metal anti-high temperature cycloid downhole motor.

The full-metal anti-high temperature cycloid downhole motor provided in the present application adopts the following technical solutions.

A full-metal anti-high temperature cycloid downhole motor comprises an outer tube, a stator fixedly mounted in the outer tube, a rotor provided in the stator and having the same height as the stator, a partition plate and a flow distribution disc respectively fixed to two ends of the stator, and a flow guide mechanism located at a side of the flow distribution disc away from the stator, and the flow guide mechanism cooperates with the flow distribution disc to perform a flow distribution to drive the rotor to rotate in the stator;

the inside of the stator is provided with N grooves distributed equidistantly on the circumference and extending through the stator along the axial direction of the outer tube, the inner side walls of the N grooves are connected end to end to form an annular inner contour surface, wherein N is a natural number greater than 1;
the rotor is formed with N−1 rotating heads provided along the axial direction of the outer tube, a working chamber is formed among the adjacent rotating heads and the inner contour surface, the partition plate and the flow distribution disc, and each rotating head is provided with an embedding slot that extends through the rotating head along the axial direction of the outer tube, one side of the embedding slot is provided with a notch of the same length as the embedding slot, a rotor copper rod that can be in rolling engagement with the inner contour surface through the notch is provided in the embedding slot, and there is a changing gap between the outer wall of the rotor copper rod and the inner wall of the embedding slot.

By adopting the above technical solution, during the rotation of the rotor, the rotor copper rod partially protrudes from the notch under the centrifugal action and is in rolling engagement with the inner contour surface, so that the traditional sliding friction between the rotor and the stator is converted into rolling friction, which greatly reduces friction resistance, reduces wear and kinetic energy loss, and improves service life. At the same time, when the liquid contains impurities, the rotor copper rod can be retracted into the embedding slot under the action of squeezing force, so that the impurities can pass through, which solves the traditional downhole problem such as jamming or wearing. The whole is processed by full-metal materials, so that the downhole motor has the characteristics of high temperature resistance.

Preferably, a stator copper rod in rolling contact with the rotor is rotatably embedded in a position of the stator between adjacent grooves.

By adopting the above technical solution, it is mainly used to further reduce the wear between the stator and the rotor and increase the service life.

Preferably, the outer side wall of the stator is attached to the inner side wall of the outer tube, and at least one flow passage extending axially along the outer tube and communicating with the flow guide mechanism is provided on the outer side wall of the stator; a second relief slot is provided at the position of the partition plate corresponding to the flow passage, a third relief slot is provided at the position of the flow distribution disc corresponding to the flow passage.

By adopting the above technical solution, multiple flow passages can be provided according to needs to increase the inlet flow rate and increase the displacement of the downhole motor.

Preferably, a water diversion cover plate is fixed on the side of the partition plate away from the stator, a first relief slot is provided at the position of the water diversion cover plate corresponding to the flow passage; a cone is integrally formed on the water diversion cover plate, the bottom surface of the cone is smaller than that of the water diversion cover plate, and the apex of the cone faces the water inlet end.

By adopting the above technical solution, when the high-pressure liquid is injected from the joint, the arrangement of the cone can greatly reduce the resistance of the high-pressure liquid, so as to quickly enter the flow guide mechanism.

Preferably, the flow guide mechanism comprises a flow distribution cylinder provided within the outer tube and communicated with the flow distribution disc, and a flow distribution shaft rotatably connected within the flow distribution cylinder to communicate the flow passage with the flow distribution cylinder, and the flow distribution shaft is gaplessly and rotatably fitted with the flow distribution cylinder;

a cardan shaft for transmission is provided between the flow distribution shaft and the rotor, a spline is provided on the outer side wall of the cardan shaft, and the opposite ends of the flow distribution shaft and the rotor is provided with a spline slot that can cooperate with the spline.

By adopting the above technical solution, during the rotation of the rotor, the cardan shaft drives the flow distribution shaft to rotate synchronously, thereby outputting power outward.

Preferably, the flow distribution shaft is rotatably supported within the flow distribution cylinder through a bearing.

By adopting the above technical scheme, it is mainly used to correct the flow distribution shaft to ensure the stable output of the flow distribution shaft.

Preferably, the outer side wall of the flow distribution shaft is provided with a first ring slot and a second ring slot, the second ring slot is provided with a liquid discharge port radially extending through the flow distribution shaft, and the end of the flow distribution shaft away from the spline slot is provided inwardly with a liquid discharge chamber communicating with the liquid discharge port;

a flow distribution ring is formed between the first ring slot and the second ring slot, and the flow distribution ring is provided with a plurality of liquid inlet slots and liquid outlet slots that are equidistantly distributed on a circumference and provided at intervals; the liquid inlet slot is communicated with the first ring slot, and the liquid outlet slot is communicated with the second ring slot;
a fourth relief slot communicating with the first ring slot is provided at the position of the flow distribution cylinder corresponding to the third relief slot, a plurality of liquid inlet channels and liquid outlet channels that are equidistantly distributed on a circumference and provided at intervals are provided inwardly from an end of the flow distribution cylinder close to the flow distribution disc along the axial direction, and the liquid inlet channel is communicated with the liquid inlet slot, and the liquid outlet channel is communicated with the liquid outlet slot;

the flow distribution disc is provided with a liquid inlet that is communicated with any liquid inlet channel to supply liquid to the corresponding working chamber, and a liquid outlet that is communicated with any liquid outlet channel to discharge the liquid in the corresponding working chamber, and the liquid inlet and the liquid outlet correspond to different working chambers.

By adopting the above technical solution, after the high-pressure liquid is injected from the joint, it enters the first ring slot sequentially through the first relief slot, the second relief slot, the flow passage, the third relief slot and the fourth relief slot. The inner wall of the flow distribution shaft matches the outer wall of the flow distribution cylinder, so the high-pressure liquid can only flow into the three liquid inlet slots, and then is injected into the high-pressure chamber through the liquid inlet slot communicated with the liquid inlet on the flow distribution disc so as to drive the rotor to rotate in the direction of the low-pressure chamber; while the high-pressure liquid in the other two liquid inlet slots impacts on the flow distribution disc, exerting an upward supporting force on the flow distribution disc, thereby offsetting part of the impact force at the water injection end so as to reduce the axial force on the bearing and increase the service life of the downhole motor.

Preferably, the end of the outer tube away from the partition plate is provided with a base for supporting the flow distribution cylinder, the end of the flow distribution shaft away from the spline slot extends through the base and to the outside of the outer tube, and the end of the outer tube close to the partition plate is provided with a joint to press the stator against the flow distribution cylinder.

By adopting the above technical solution, the arrangement of the base and the joint is used to press and fix the water diversion cover plate, the baffle plate, the stator, the rotor, the flow distribution disc and the flow guide mechanism within the outer pipe, and it is convenient to replace any of the above components according to needs, which improves the service life of the downhole motor.

Preferably, the joint comprises an assembly section and a connecting section that are integrally formed, and an assembly section presses the stator against the flow guide mechanism by being fixedly connected with the inner wall of the outer tube; and the inner wall of the connecting section is provided with internal threads.

By adopting the above technical solution, the arrangement of the internal thread facilitates the connection of a high-pressure water circuit.

In summary, the present application comprises at least one of the following beneficial technical effects.

1. In the present application, the rotor copper rod is provided on the rotor, so that traditional sliding friction between the rotor and the stator is converted into rolling friction, which greatly reduces friction resistance, reduces wear and kinetic energy loss, and improves service life. At the same time, when the liquid contains impurities, the rotor copper rod can be retracted into the embedding slot under the action of squeezing force, so that the impurities can pass through, which solves the traditional downhole problem that the motor is easy to jam and wear. The whole is processed by full-metal materials, so that the downhole motor has the characteristics of high temperature resistance.

2. By making the high pressure liquid in at least two liquid inlet slots impact on the flow distribution disc, the flow distribution disc can get an upward supporting force, thereby offsetting part of the impact force at the water injection end, reducing the axial force acting on the bearing, and improving the service life of the downhole motor;

3. By increasing the inlet flow of the flow guide mechanism, the output torque of the downhole motor is greatly improved.

