A multi-stage all-metal concentric motion screw motor

Abstract

The application discloses a kind of multistage full metal concentric motion screw motor, specifically relates to drilling equipment technical field, including two motor housings, each motor housing is provided with rotor, motor housing and rotor are made of metal material, the outside of rotor and the inside of motor housing are equipped with multiple spiral grooves, and the number of spiral groove on the inner surface of motor housing is greater than the number of spiral groove on the outside of rotor, connecting shell is equipped between the two motor housings, sealing mechanism is equipped between connecting shell and motor housing, connecting shell is rotatably provided with connecting shaft, two plug shafts are provided on connecting shaft by universal joint, the end of rotor is provided with cylinder, and multiple buffering mechanisms are provided on motor housing.In the application, motor housing and rotor can withstand higher downhole temperature, can better adapt to complex and harsh drilling environment, the torque of each rotor is superimposed, the energy use efficiency is improved, the buffering mechanism can reduce metal material wear, and prolong the service life of equipment.

Description

Technical Field

[0001] This invention relates to the field of drilling equipment technology, and more specifically, to a multi-stage all-metal concentric screw motor. Background Technology

[0002] Screw drills are drilling equipment used in oil well drilling, playing a vital role in the field of petroleum exploration. They use a rotating screw to drive the drill bit into the formation, simultaneously transporting rock cuttings and drilling fluid from the bottom of the well to the wellhead, thus achieving the purpose of oil well drilling. In screw drilling, the screw motor is one of the core components, playing a crucial role in rotating the drill bit and transporting materials. The screw motor is a positive displacement motor that converts fluid pressure energy into mechanical energy, and it is a core technology in modern directional drilling and downhole power tools. Its emergence has greatly promoted technological progress in fields such as petroleum drilling, geological exploration, mining, and special engineering.

[0003] In recent years, due to increasingly demanding requirements for drilling tools in the energy sector, and the pressure imbalance in oil and gas wells during the later stages, oil and gas well construction must employ multi-media mixed operations involving gas, liquid, and foam. Existing screw motor stators are all constructed with metal shells and rubber linings, resulting in low pressure resistance, poor wear resistance, and inability to withstand high temperatures; the only differences are in their internal structure and technical parameters. When drilling to greater depths in oil and gas wells, the formation temperature becomes extremely high, far exceeding the heat resistance range of rubber.

[0004] Furthermore, the driving force of a single screw motor on the drill bit is limited, resulting in a relatively small drilling force. This necessitates increasing the power of the water pump to increase drilling force, thus increasing drilling costs. The water still retains some pressure after flowing out of the drill bit, leading to a certain degree of energy waste. During screw motor operation, the pressure between the stator and rotor is high, and the lateral vibration generated by the drilling fluid impacting the rotor further reduces the equipment's lifespan.

[0005] To address these issues, this invention proposes a multi-stage all-metal concentric screw motor. Summary of the Invention

[0006] In order to overcome the above-mentioned defects of the prior art, embodiments of the present invention provide a multi-stage all-metal concentric motion screw motor, which solves the problems mentioned in the background art by setting a connecting part and a buffer part.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a multi-stage all-metal concentric screw motor, comprising two concentric motor housings with a gap between them, and further comprising:

[0008] The rotating part includes two rotors respectively disposed in two motor housings. Both the motor housings and the rotors are made of metal. The rotors are aligned with the length direction of the motor housings. Multiple helical grooves are provided on the outside of the rotors and inside the motor housings. The multiple helical grooves are evenly distributed along the circumference of the rotors. The number of helical grooves on the inner surface of the motor housings is greater than the number of helical grooves on the outside of the rotors, so that the rotors can roll inside the motor housings.

[0009] The connecting part includes a connecting housing located in the gap between two motor housings. A sealing mechanism is provided between the connecting housing and the outside of the motor housing. The sealing mechanism connects the connecting housing and the motor housing to seal the connecting housing and the motor housing, allowing water to flow from one motor housing to the other while maintaining water pressure. A connecting shaft is rotatably mounted inside the connecting housing. Two symmetrically distributed insert shafts are provided on the connecting shaft via universal joints, allowing the two insert shafts to rotate out of concentricity. The insert shafts cooperate with the rotor end, and the torque of the insert shafts and the rotor can be transmitted to each other.

[0010] The buffer section includes a cylinder disposed at the end of the rotor, the cylinder being concentric with the rotor. The motor housing is provided with multiple buffer mechanisms evenly distributed along its circumference. The cylinder is located between the multiple buffer mechanisms, and each of the multiple buffer mechanisms can contact the outer surface of the cylinder and buffer it when the cylinder moves. When the cylinder rolls with the rotor, the outer surface of the cylinder alternately acts on the multiple buffer mechanisms, reducing the force between the rotor and the motor housing, thereby reducing wear.

[0011] Preferably, the sealing mechanism includes flanges disposed at the ends of the motor housing and the connecting housing. Each flange has multiple through holes. Multiple bolts are evenly distributed along the circumference between two adjacent flanges. The bolts pass through two adjacent through holes to connect the motor housing and the connecting housing as a whole. A sealing ring is provided at the end of the motor housing. The outer surface of the sealing ring can contact the inner surface of the connecting housing.

[0012] Preferably, the sealing ring is tapered on the outside, and the inner surface of the end of the connecting housing matches the inclined surface of the outer side of the sealing ring, which helps to enhance the sealing effect between the motor housing and the connecting housing, and also makes it easier to align the center of the connecting housing with the center of the motor housing during installation.

[0013] Preferably, the connecting housing is provided with a plurality of connecting plates evenly distributed along its circumference, and gaps are provided between the plurality of connecting plates to ensure the passage of water. A fixed ring is provided between the plurality of connecting plates, and a rotating ring is rotatably connected inside the fixed ring. A sleeve is hinged inside the rotating ring. The sleeve is slidably connected to the connecting shaft. The sleeve and the connecting shaft can swing laterally, and the connecting shaft can slide up and down along the length of the sleeve.

[0014] Preferably, the sleeve is inclined, the connecting shaft is kept inclined, the two insert shafts are not concentric, and the two rotors rotate in a non-concentric manner, so that the lateral vibrations generated by the two rotors can partially cancel each other out, reducing the degree of vibration damage to the equipment.

[0015] Preferably, the rotor end is provided with a spline groove, and the insertion shaft end is provided with a spline that mates with the spline groove. When the spline is inserted into the spline groove, the rotor and the insertion shaft rotate synchronously.

[0016] Preferably, the buffer mechanism includes two pressure rods hinged to the motor housing, with a gap between the hinge points of the two pressure rods and the motor housing, and the two pressure rods are symmetrically distributed. Each pressure rod has a roller rotatably connected to its free end, and the roller can roll along the outer surface of the corresponding cylinder. Each pressure rod has a pull ring in the middle, and the pull ring is located at the opposite end of the two pressure rods. An elastic element is provided between the two pull rings, and the elastic element always has the tendency to pull the two pull rings towards the middle.

[0017] Preferably, a stop block fixed to the motor housing is provided in the gap between the two pressure rods. The end of the stop block is separated from the middle and fits against the two pressure rods respectively, so as to separate the two pressure rods when not in a buffer state and prevent collision between the cylinder and the pressure rods.

[0018] The technical effects and advantages of this invention are as follows:

[0019] 1. Traditional screw motor stators consist of a metal casing and a rubber lining, which have low pressure resistance, are not wear-resistant, and are not heat-resistant. They are prone to aging, expansion, detachment, and damage in high-temperature, highly corrosive media or oil-based drilling fluid environments. In contrast, the motor casing and rotor of this invention are made of all-metal materials, which can withstand higher downhole temperatures and are insensitive to oil-based drilling fluids and various chemical additives. Under suitable operating conditions, its mechanical wear life far exceeds that of screw motors using rubber or elastic materials, making it better suited to complex and harsh drilling environments.

[0020] 2. A single traditional screw motor has limited driving force for the drill bit, resulting in weak drilling force. This necessitates increasing the power of the water pump to enhance the drilling force, increasing costs and wasting energy. This invention employs a multi-stage structure, with connecting parts linking multiple motor housings and rotors. Water flow sequentially passes through each stage of the motor housing, driving the rotors to rotate. The torques of each rotor stage are superimposed, collectively driving the drill bit, improving energy efficiency and reducing drilling costs. Operators can also connect more independent screw motor motion units in series as needed to achieve the effect of a multi-stage screw motor, further enhancing the driving force.

[0021] 3. When the rotor is rolling, the high pressure and lateral vibration caused by the water flow, combined with the metal materials of both the rotor and the motor housing, accelerate the wear of the metal materials and reduce the service life of the equipment. This invention incorporates a buffer section. A cylinder is installed at the end of the rotor, and multiple buffer mechanisms are installed on the motor housing. As the cylinder rotates, it alternately presses against the buffer mechanisms. The elastic elements in the buffer mechanisms generate tension, reducing the pressure between the rotor and the motor housing and mitigating wear on the metal materials. Simultaneously, the inclined connecting shaft prevents adjacent rotors from rotating concentrically. The lateral vibrations generated by the two rotors can partially cancel each other out, reducing the damage caused by vibration and thus extending the service life of the equipment. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0023] Figure 2 This is a top-view schematic diagram of the overall structure of the present invention.

[0024] Figure 3 For the present invention Figure 2 An enlarged schematic diagram of part A in the middle.

[0025] Figure 4 This is a schematic diagram of the motor housing and the connecting housing separated in this invention.

[0026] Figure 5 This is a schematic diagram of the structure of the motor housing and rotor in this invention.

[0027] Figure 6 This is a front view sectional diagram of the overall structure of the present invention.

[0028] Figure 7 This is a schematic diagram of the connecting part in this invention.

[0029] Figure 8 This is a top sectional view of the connecting part in this invention.

[0030] Figure 9 This is a front sectional view of the connecting part in this invention.

[0031] Figure 10This is an exploded view of the connecting part in this invention.

[0032] Figure 11 This is a schematic diagram of the motor housing in this invention.

[0033] Figure 12 This is a front sectional view of the motor housing in this invention.

[0034] The attached figures are labeled as follows:

[0035] 1. Motor housing; 2. Rotating part; 201. Rotor; 202. Spiral groove; 3. Connecting part; 301. Connecting housing; 302. Sealing mechanism; 3021. Flange; 3022. Bolt; 3023. Sealing ring; 303. Connecting shaft; 304. Universal joint; 305. Insert shaft; 4. Buffer part; 401. Cylinder; 402. Buffering mechanism; 4021. Pressure rod; 4022. Roller; 4023. Pull ring; 4024. Elastic element; 5. Connecting plate; 6. Fixed ring; 7. Rotating ring; 8. Sleeve; 9. Spline groove; 10. Spline; 11. Stop block. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] Please see Figures 1 to 6 As shown, a multi-stage all-metal concentric screw motor according to an embodiment of the present invention includes a motor housing 1, and further includes:

[0039] The rotating part 2 includes a rotor 201 disposed inside the motor housing 1. Both the motor housing 1 and the rotor 201 are made of metal. The rotor 201 is aligned with the length direction of the motor housing 1. Multiple spiral grooves 202 are provided on the outside of the rotor 201 and inside the motor housing 1. The multiple spiral grooves 202 are evenly distributed along the circumference of the rotor 201, and the number of spiral grooves 202 on the inner surface of the motor housing 1 is greater than the number of spiral grooves 202 on the outside of the rotor 201, so that the rotor 201 can roll inside the motor housing 1.

[0040] It should be noted that the bottom of rotor 201 needs to be connected to a drill bit in the prior art, and the top of motor housing 1 needs to be connected to the water pump outlet pipe.

[0041] During use, the operator uses existing support equipment to erect the motor housing 1, then aligns the drill bit with the drilling position, and simultaneously starts the water pump. The water pump sends water into the motor housing 1 through the outlet pipe. The water flow has a certain water pressure, the magnitude of which is related to the power of the water pump. The water flows from top to bottom through the spiral groove 202. The water pressure acts between the motor housing 1 and the rotor 201. Since the motor housing 1 is in a non-rotating state, the rotor 201 begins to rotate under the action of water pressure. Because the number of spiral grooves 202 on the inner surface of the motor housing 1 is greater than the number of spiral grooves 202 on the outer surface of the rotor 201, the protrusion between two adjacent spiral grooves 202 on the rotor 201 gets stuck in the spiral groove 202 inside the motor housing 1. The water pressure drives the rotor 201 to roll along the inner wall of the motor housing 1. The rotor 201 drives the drill bit to rotate, and the drill bit begins to drill. After the water flows through the motor housing 1, it sprays out from the hole in the drill bit. The sprayed water can cool the drill bit and prevent it from overheating and being damaged.

[0042] Traditional screw motors contain rubber or elastic materials, which are prone to aging, swelling, detachment, and damage in high-temperature, highly corrosive media or environments containing oil-based drilling fluids, resulting in a limited lifespan. In contrast, the motor housing 1 and rotor 201 in this device are made of metal, which can withstand higher downhole temperatures and is insensitive to oil-based drilling fluids and various chemical additives. Under suitable operating conditions, its mechanical wear life far exceeds that of screw motors using rubber or elastic materials.

[0043] Example 2

[0044] In actual use, it was found that when the water flow generated by the pump drives the rotor 201 to rotate, the driving force of the single motor housing 1 and the rotor 201 on the drill bit is limited, resulting in a small drilling force. The drilling force can only be increased by increasing the power of the pump, which increases the drilling cost. Moreover, the water flow still has a certain water pressure after it flows out of the drill bit, which causes a certain degree of energy waste. Further improvements are made based on the above embodiment.

[0045] Please see Figures 1 to 10 As shown, there are two motor housings 1 and two rotors 201. The two motor housings 1 are concentric and there is a gap between them. The two rotors 201 are located inside the two motor housings 1 respectively.

[0046] A connecting part 3 is provided in the gap between the two motor housings 1. It includes a connecting housing 301 located in the gap between the two motor housings 1. A sealing mechanism 302 is provided between the connecting housing 301 and the outside of the motor housing 1. The sealing mechanism 302 can connect the connecting housing 301 and the motor housing 1 to seal the connecting housing 301 and the motor housing 1, so that water can flow from one motor housing 1 to the other motor housing 1 and ensure the pressure of the water flow. A connecting shaft 303 is rotatably provided in the connecting housing 301. Two symmetrically distributed insert shafts 305 are provided on the connecting shaft 303 through a universal joint 304, so that the two insert shafts 305 can rotate out of concentricity. The insert shafts 305 cooperate with the end of the rotor 201, and the torque of the insert shafts 305 and the rotor 201 can be transmitted to each other.

[0047] Please see Figure 2 , Figure 3 and Figure 4 As shown, the sealing mechanism 302 includes flanges 3021 disposed at the ends of the motor housing 1 and the connecting housing 301. Each flange 3021 has multiple through holes. Between two adjacent flanges 3021, multiple bolts 3022 are evenly distributed along their circumference. The bolts 3022 pass through the two adjacent through holes to connect the motor housing 1 and the connecting housing 301 into one unit. A sealing ring 3023 is provided at the end of the motor housing 1. The outer surface of the sealing ring 3023 can contact the inner surface of the connecting housing 301.

[0048] Please see Figure 2 and Figure 3 As shown, the sealing ring 3023 is tapered on the outside, and the inner surface of the end of the connecting housing 301 matches the inclined surface of the sealing ring 3023 on the outside, which helps to enhance the sealing effect between the motor housing 1 and the connecting housing 301, and makes it easy to align the center of the connecting housing 301 with the center of the motor housing 1 during installation.

[0049] Please see Figure 8 , Figure 9 and Figure 10 As shown, the connecting housing 301 is provided with a plurality of connecting plates 5 evenly distributed along its circumference. There are gaps between the plurality of connecting plates 5 to ensure the passage of water. A fixing ring 6 is provided between the plurality of connecting plates 5. A rotating ring 7 is rotatably connected inside the fixing ring 6. A sleeve 8 is hinged inside the rotating ring 7. The sleeve 8 is slidably connected to the connecting shaft 303. The sleeve 8 and the connecting shaft 303 can swing laterally, and the connecting shaft 303 can slide up and down along the length of the sleeve 8.

[0050] Please see Figure 5 , Figure 7 and Figure 10As shown, the rotor 201 has a spline groove 9 at its end, and the insert shaft 305 has a spline 10 that mates with the spline groove 9 at its end. When the spline 10 is inserted into the spline groove 9, the rotor 201 and the insert shaft 305 rotate synchronously.

[0051] Based on the above embodiments, in use, the connecting housing 301 is initially separated from the two motor housings 1. The operator places the connecting housing 301 between the two motor housings 1, so that the inner surface of one end of the connecting housing 301 fits against the inclined surface of the sealing ring 3023. The inclined surface of the sealing ring 3023 can act as a guide, making it easier for the operator to align the center of the connecting housing 301 and the motor housing 1, so that the flanges 3021 on the connecting housing 301 and the motor housing 1 fit together. Then, multiple bolts 3022 are used to fix the two adjacent flanges 3021 together, pressing the inclined surface of the end of the connecting housing 301 against the inclined surface of the end of the sealing ring 3023. Through the sealing effect, the internal space of the connecting housing 301 and the motor housing 1 is connected. Then, the other end of the connecting housing 301 is connected to the other motor housing 1. At this time, the two motor housings 1 and the interior of the connecting housing 301 are in a connected state.

[0052] The workers connected the upper motor housing 1 to the water pump's outlet pipe, installed the drill bit on the lower motor housing 1, and used existing support equipment to erect both motor housings 1. Then, they aligned the drill bit with the drilling position and started the water pump. The water pump sent water through the outlet pipe into the upper motor housing 1. The water flow first passed through the upper spiral groove 202, driving the upper rotor 201 to rotate. The upper rotor 201 drove the upper spline 10 and the insert shaft 305 to rotate through the spline groove 9. The upper insert shaft 305 drove the connecting shaft 303 to rotate through the universal joint 304. The connecting shaft 303 drove the lower insert shaft 305 to rotate. The lower insert shaft 305 drove the lower rotor 201 to rotate through the lower spline 10 and spline groove 9. The lower rotor 201 drove the drill bit to rotate.

[0053] When the water flows through the connecting housing 301 and enters the lower motor housing 1, the water flows into the lower spiral groove 202. The pressure of the water flows acts on the lower rotor 201, driving the lower rotor 201 to rotate. The torques of the two rotors 201 are superimposed and finally drive the drill bit to rotate, thereby increasing the drilling force of the drill bit, achieving higher energy efficiency and reducing drilling costs.

[0054] Workers can also fix more connecting housings 301 and motor housing 1 at the end of the upper motor housing 1 to connect multiple independent screw motor motion units into a whole. When the water pump is turned on, it ensures that the water flow can pass through each stage in sequence to superimpose torque, and at the same time, it efficiently and concentrically transmits the rotational motion generated by each stage rotor 201 to the output shaft, which drives the drill bit to rotate, thereby achieving the effect of using a multi-stage screw motor.

[0055] Example 3

[0056] In actual use, it was found that when the rotor 201 rolls along the inner wall of the motor housing 1, since both the rotor 201 and the motor housing 1 are made of metal materials, and the pressure between the rotor 201 and the motor housing 1 is relatively large, coupled with the lateral vibration generated by the water flow impacting the rotor 201, the wear of the metal materials will be accelerated, and the service life of the equipment will be reduced rapidly. Further improvements were made based on the above embodiments.

[0057] Please see Figure 4 As shown, the screw motor also includes a buffer section 4, which includes a cylinder 401 disposed at the end of the rotor 201. The cylinder 401 is concentric with the rotor 201. The motor housing 1 is provided with a plurality of buffer mechanisms 402 evenly distributed along its circumference. The cylinder 401 is located between the plurality of buffer mechanisms 402. The plurality of buffer mechanisms 402 can contact the outer surface of the cylinder 401 and buffer it when the cylinder 401 moves. When the cylinder 401 rolls with the rotor 201, the outside of the cylinder 401 alternately acts on the plurality of buffer mechanisms 402, reducing the force between the rotor 201 and the motor housing 1, thereby reducing wear.

[0058] Please see Figure 8 As shown, the sleeve 8 is inclined, the connecting shaft 303 is kept inclined, the two insert shafts 305 are not concentric, and the two rotors 201 rotate in a non-concentric manner, so that the lateral vibration generated by the two rotors 201 can cancel each other out to a certain extent, reducing the degree of damage to the equipment caused by vibration.

[0059] Please see Figure 11 and Figure 12 As shown, the buffer mechanism 402 includes two pressure rods 4021 hinged to the motor housing 1. There is a gap between the hinge points of the two pressure rods 4021 and the motor housing 1, and the two pressure rods 4021 are symmetrically distributed. Each pressure rod 4021 has a roller 4022 rotatably connected to its free end. The roller 4022 can roll along the outer surface of the corresponding cylinder 401. Each pressure rod 4021 has a pull ring 4023 in the middle. The pull ring 4023 is located at the opposite end of the two pressure rods 4021. An elastic element 4024 is provided between the two pull rings 4023. The elastic element 4024 always has the tendency to pull the two pull rings 4023 toward the middle.

[0060] Please see Figure 12 As shown, a stop block 11 fixed to the motor housing 1 is provided in the gap between the two pressure rods 4021. The end of the stop block 11 is separated from the middle and fits against the two pressure rods 4021 respectively. It is used to separate the two pressure rods 4021 when not in the buffer state to prevent the cylinder 401 from colliding with the pressure rods 4021.

[0061] Based on the above embodiments, during use, after the multi-stage screw motor is installed and the water pump is turned on, the water flow drives multiple rotors 201 to roll sequentially from top to bottom, and the rotational motion of multiple rotors 201 is collected into the drill bit, driving the drill bit to rotate. Since the insert shaft 305 is inserted into the end of the rotor 201, the insert shaft 305 and the rotor 201 are concentric. Two adjacent insert shafts 305 are connected by a connecting shaft 303. The sleeve 8 is inclined, and the connecting shaft 303 inside the sleeve 8 is also inclined, so that the insert shafts 305 at both ends of the connecting shaft 303 are not concentric, that is, two adjacent rotors 201 are not concentric. When two adjacent rotors 201 roll along the inner wall of the motor housing 1, the lateral vibration generated by the water flow impacting the two rotors 201 can cancel each other out to a certain extent, thereby reducing the degree of vibration damage to the equipment.

[0062] When the rotor 201 rolls, it drives the inclined connecting shaft 303 to swing through the insert shaft 305. The inclined connecting shaft 303 drives the sleeve 8 to swing, and the sleeve 8 drives the rotating ring 7 to rotate around the fixed ring 6. The gap between the fixed ring 6 and the multiple connecting plates 5 between the connecting housing 301 ensures the efficiency of water flow.

[0063] When the rotor 201 rolls, it also drives the cylinder 401 to rotate around the center of the motor housing 1. The cylinder 401 alternately squeezes the rollers 4022 in multiple buffer mechanisms 402. When the cylinder 401 squeezes one of the rollers 4022, the roller 4022 rolls along the outer surface of the cylinder 401. The cylinder 401 drives the corresponding pressure rod 4021 to swing towards the motor housing 1. The pressure rod 4021 drives the corresponding pull ring 4023 to swing. The pull ring 4023 pulls the elastic element 4024 to move. Since the other pressure rod 4021 in the buffer mechanism 402 is blocked by the stop block 11 and cannot swing, the pull ring 4023 on the other pressure rod 4021 remains stationary, and the elastic element 4024 is gradually stretched.

[0064] As the cylinder 401 continues to rotate, when both rollers 4022 in the same buffer mechanism 402 are in contact, the cylinder 401 drives the two pressure rods 4021 to swing simultaneously through the rollers 4022, causing the two pressure rods 4021 to gradually separate. The two pressure rods 4021 drive the two pull rings 4023 to gradually separate, and the two pull rings 4023 pull the elastic element 4024 to both sides. The deformation speed of the elastic element 4024 increases, enhancing the buffering effect of the elastic element 4024. The tension generated by the elongation of the elastic element 4024 can reduce the pressure between the rotor 201 and the motor housing 1. As the rotor 201 rotates continuously, the cylinder 401 alternately contacts multiple buffer mechanisms 402 in the circumferential direction. The multiple buffer mechanisms 402 alternately buffer the cylinder 401 and the rotor 201, reducing the intensity of vibration and thus reducing the wear of metal materials.

[0065] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A multi-stage all-metal concentric motion screw motor comprising two concentric motor housings (1), characterized in that, Also include: The rotating part (2) includes two rotors (201) arranged in two motor housings (1) respectively, the motor housings (1) and the rotors (201) are made of metal material, the rotors (201) are provided with a plurality of spiral grooves (202) on the outside, and the motor housings (1) are provided with a plurality of spiral grooves (202) on the inside, and the number of spiral grooves (202) on the inside of the motor housing (1) is greater than that on the outside of the rotor (201); The connecting part (3) includes a connecting shell (301) between the two motor housings (1), the connecting shell (301) is provided with a sealing mechanism (302) between the outside of the motor housing (1), for sealing the connecting shell (301) and the motor housing (1), the connecting shell (301) is rotatably provided with a connecting shaft (303), the connecting shaft (303) is provided with two symmetrically distributed plug shafts (305) through the universal joint (304), the plug shaft (305) is matched with the end of the rotor (201); The buffer part (4) includes a cylinder (401) arranged at the end of the rotor (201), the motor housing (1) is provided with a plurality of buffer mechanisms (402) uniformly distributed along the circumferential direction, the cylinder (401) is located between the plurality of buffer mechanisms (402), and the plurality of buffer mechanisms (402) can contact the outer surface of the cylinder (401) and buffer the cylinder (401) when moving; The connecting shell (301) is provided with a plurality of connecting plates (5) uniformly distributed along the circumferential direction, a plurality of connecting plates (5) are provided with a fixed ring (6), the fixed ring (6) is rotatably connected with a rotating ring (7), the rotating ring (7) is hingedly connected with a sleeve (8), the sleeve (8) is inclined and slidably connected with the connecting shaft (303); The buffer mechanism (402) includes two hingedly connected pressure rods (4021) on the motor housing (1), the two pressure rods (4021) are symmetrically distributed, the free end of each pressure rod (4021) is rotatably connected with a roller (4022), and the middle part of each pressure rod (4021) is provided with a pull ring (4023), and the two pull rings (4023) are provided with an elastic element (4024); When the cylinder (401) extrudes one of the rollers (4022), the corresponding side pressure rod (4021) is driven to swing, and the other pressure rod (4021) is stationary, when the cylinder (401) contacts with two rollers (4022) in the same buffer mechanism (402), the two pressure rods (4021) are driven to swing at the same time, and the deformation speed of the elastic element (4024) is accelerated.

2. The multi-stage all-metal concentric motion screw motor of claim 1, wherein, The sealing mechanism (302) includes a flange (3021) arranged at the end of the motor housing (1) and the connecting shell (301), a plurality of bolts (3022) are arranged between two adjacent flanges (3021) along the circumferential direction, a sealing ring (3023) is arranged at the end of the motor housing (1), and the outer surface of the sealing ring (3023) can contact the inner surface of the connecting shell (301).

3. The multi-stage all-metal concentric motion screw motor of claim 2, wherein, The sealing ring (3023) is conical outside, and the inner surface of the end of the connecting shell (301) is matched with the slope of the outer part of the sealing ring (3023).

4. The multi-stage all-metal concentric motion screw motor of claim 1, wherein, The end of the rotor (201) is provided with a spline groove (9), and the end of the inserting shaft (305) is provided with a spline (10) matched with the spline groove (9).

5. The multi-stage all-metal concentric motion screw motor of claim 1, wherein, The two pressing rods (4021) are provided with a stop block (11) fixed with the motor shell (1), so as to separate the two pressing rods (4021).

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