Sand prevention sealing structure and sealing method for piston of electric submersible pump

Abstract

The invention belongs to the technical field of electric submersible pumps, and discloses a sand-prevention sealing structure and a sand-prevention sealing method for an electric submersible pump piston. The sand prevention sealing structure comprises three sealing structures arranged on the piston; the first sealing structure is an upper seal formed by attaching the upper sand prevention sealing check ring to the cylinder body, the second sealing structure is a main seal formed by attaching the piston ring to the cylinder body, and the third sealing structure is a lower seal formed by attaching the lower sand prevention sealing check ring to the cylinder body. Sand impurities in oil are effectively prevented from entering a sealing surface, mechanical abrasion and sealing failure caused by sand are avoided, the sealing reliability of the electric submersible pump in a sand-containing oil well is remarkably improved through the structure, the service life of a piston ring and a cylinder body is prolonged, and meanwhile the equipment failure risk caused by sand clamping stagnation is reduced.

Description

Technical Field

[0001] This invention belongs to the field of submersible electric pump technology, and particularly relates to a sand-proof sealing structure and sealing method for a submersible electric pump piston. Background Technology

[0002] In oil extraction operations, submersible electric pumps (SAPs) are crucial downhole lifting equipment, and the sealing performance of their core component, the piston, directly affects pump efficiency and equipment lifespan. Current technologies largely rely on the radial clamping force of piston rings for sealing. When sand particles intrude, leakage channels form at the oblique openings of the piston rings, and uniform wear across multiple piston rings leads to "tandem failure." Furthermore, there is a lack of an active sand-guiding mechanism, resulting in continuous damage to the sealing surface from abrasive particles. In addition, the problem of excessively large piston axial dimensions, which fail to effectively intercept sand particles, and the issue of sand deposition in the sealing zone remains unresolved. Summary of the Invention

[0003] To overcome the problems existing in related technologies, the present invention discloses an anti-sand sealing structure and sealing method for a submersible electric pump piston. The technical solution is as follows: a sand-proof sealing structure for a submersible electric pump piston, the structure including three sealing structures on the piston; the first sealing structure is an upper seal formed by the upper sand-proof sealing ring fitting with the cylinder body, the second sealing structure is a main seal formed by the piston ring fitting with the cylinder body, and the third sealing structure is a lower seal formed by the lower sand-proof sealing ring fitting with the cylinder body.

[0004] The piston engages with the piston rings in a radial direction through an annular mounting groove. The piston rings fit tightly against the cylinder body to form a sealing surface, which prevents oil leakage from the sealing surface.

[0005] The piston has annular grooves at its upper and lower ends for mounting an upper sand-proof sealing ring and a lower sand-proof sealing ring, respectively. The upper and lower sand-proof sealing rings are symmetrically installed at the upper and lower ends of the piston.

[0006] The upper sand-proof sealing ring has a spiral flow channel on its inner inclined surface near the axis, which allows sand particles on the upper part of the piston to enter the central axis position along the spiral flow channel and flow back into the working chamber. The spiral flow channel is opened from the outside to the inside at the same depth or gradually deeper.

[0007] The piston rings are not less than three in number, and each piston ring has an oblique opening. The multiple piston rings are evenly staggered in the circumferential direction of the piston to form a multi-level sealing defense.

[0008] The upper and lower sandproof sealing rings are molded from polytetrafluoroethylene (PTFE) material.

[0009] The upper and lower sand-proof sealing rings are installed in a floating manner. The core of this floating installation lies in maintaining a slight axial and radial clearance between the ring and the piston annular groove. When the cylinder deforms due to temperature changes or pressure fluctuations, the ring can move freely within the groove, compensating for changes in the clearance between the cylinder and piston through its own displacement, thus preventing hard jamming. For example, when the cylinder expands thermally, causing the inner diameter to shrink, the ring is compressed and contracts into the piston groove; conversely, it expands outward to maintain contact with the cylinder, automatically compensating for clearance changes caused by cylinder deformation or eccentricity.

[0010] Another objective of this invention is to provide a sand-proof sealing method for a sand-proof sealing structure of a submersible electric pump piston. The method includes: The design utilizes a triple-sealing structure to form a stepped sand-proof system, creating a sand barrier. This allows sand particles to flow back into the working chamber under the action of the first sealing structure. The second sealing structure further seals any leaked oil, and the third sealing structure achieves zero leakage.

[0011] Methods to allow sand particles to flow back into the working chamber under the action of the first sealing structure include: Step 1: Combining particle-liquid interaction, paper adhesion resistance, and particle characteristics, set the sliding angle of sand particles on the upper surface of the upper sand-proof sealing ring in the liquid-solid two-phase system. Slide angle Represented as: In the formula, The effective coefficient of friction includes both dry friction and the viscous effect of the liquid; It is a constant; For effective cohesion, including liquid bridging forces and van der Waals forces: In the formula, The internal friction angle of sand grains in their dry state. For crude oil dynamic viscosity, For sand particle density, The diameter of the sand grains. For shear rate, This is the viscosity correction factor; Step 2: Substitute the sliding angle of the sand particles on the inclined surface of the upper sand-proof sealing ring according to the sand-containing working conditions and calculate to obtain the actual sliding angle under working conditions; Step 3: Based on the obtained actual working condition sliding angle, set the angle between the upper surface of the upper sand-proof sealing ring and the upper end face of the piston, and obtain the inner inclined surface of the upper sand-proof sealing ring near the piston axis based on the set angle. Step 4: Based on the inner inclined surface of the upper anti-sand seal ring near the piston axis, the resultant force of the sand particles being impacted by the oil and the reaction force of the upper anti-sand seal ring points towards the working chamber, thereby guiding the sand particles back into the working chamber.

[0012] The actual sliding angle in step two is 60°. The included angle set in step three, and the inner slope of the upper sand-proof sealing ring near the piston axis, are 60°-90°.

[0013] Combining all the above technical solutions, the beneficial effects of this invention are as follows: First, this invention provides a sand-proof sealing structure for piston rings of submersible electric pumps, including a cylinder body, an upper sand-proof sealing ring, a piston, a piston ring, a lower sand-proof sealing ring, and a piston rod. The piston has multiple annular piston mounting grooves circumferentially. When the piston reciprocates linearly with the piston rod, a sealing surface is formed by the piston ring contacting the cylinder body. Split-type sand-proof rings are installed at both ends of the piston, effectively preventing sand particles and impurities in the oil from entering the sealing surface, thus avoiding mechanical wear and sealing failure caused by sand particles. This structure significantly improves the sealing reliability of submersible electric pumps in sand-containing oil wells, extends the service life of the piston ring and cylinder body, and reduces the risk of equipment failure due to sand particle jamming.

[0014] Secondly, the triple sand-proof sealing structure of this invention can significantly improve the service life of submersible electric pumps in sand-bearing oil wells, reduce the failure rate caused by sand particles stuck, and reduce the later maintenance costs of submersible electric pumps. Furthermore, it solves the vicious cycle of "abrasive wear-intensified leakage" caused by sand particles depositing on the sealing surface. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure; Figure 1 This is a schematic diagram of the sand-proof sealing structure for the piston of a submersible electric pump provided in an embodiment of the present invention; Figure 2 This is a rendering of a three-dimensional model of the split-type sand-proof sealing ring provided in an embodiment of the present invention; Figure 3 This is a top view of a split-type sand-proof sealing ring provided in an embodiment of the present invention; Figure 4 This is a front view of a split-type sand-proof sealing ring provided in an embodiment of the present invention; Figure 5 This is a rear view of the split-type sand-proof sealing ring provided in an embodiment of the present invention; The following are the labels in the diagram: 1. Cylinder block; 2. Upper sand seal ring; 3. Piston; 4. Piston ring; 5. Lower sand seal ring; 6. Piston rod; 7. Annular groove; Detailed Implementation To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0016] The innovation of this invention lies in the following: This invention adopts a triple-step sealing system. The first stage is formed by the upper sealing ring contacting the cylinder 1 to form a dynamic seal. Its inclined spiral flow channel design enables sand particles to flow autonomously. The second stage is formed by the staggered arrangement of three inclined open piston rings 4 to form the main seal. The third stage is the lower sealing ring to ensure zero leakage. Through floating installation and the pressure self-tightening effect of piston rings 4, efficient sand particle interception and reliable sealing are achieved under the condition that the length of piston 3 is shortened by 40%-50%.

[0017] Example 1: The piston assembly for the sand-proof sealing structure of a submersible electric pump piston provided in this embodiment of the invention includes a piston body and a piston rod 6. Multiple annular mounting grooves are evenly arranged around the piston 3 for mounting multiple piston rings 4. Split-type sand-proof sealing rings (including an upper sand-proof sealing ring 2 and a lower sand-proof sealing ring 5) are respectively provided at the upper and lower ends of the piston 3, forming a three-layer sealing structure together with the piston rings 4.

[0018] Specifically, such as Figures 1-5 As shown, the sand-proof sealing structure for a submersible electric pump piston provided in this embodiment of the invention includes three sealing structures on the piston 3; the first sealing structure is an upper seal formed by the upper sand-proof sealing ring 2 fitting with the cylinder body 1; the second sealing structure is a main seal formed by the piston ring 4 fitting with the cylinder body 1; and the third sealing structure is a lower seal formed by the lower sand-proof sealing ring 5 fitting with the cylinder body 1. This can effectively prevent sand particles larger than 50μm from entering. For example, the piston 3 engages with the piston ring 4 in the radial direction through an annular mounting groove. The piston ring 4 fits tightly against the cylinder 1 to form a sealing surface, preventing oil leakage from the sealing surface. The piston 3 has annular grooves 7 at its upper and lower ends, on which the upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5 are respectively installed. The upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5 are symmetrically installed at the upper and lower ends of the piston 3 to prevent sand particles from entering and damaging the seal. The upper sand-proof sealing ring 2 has a spiral flow channel on its inner inclined surface near the axis, which allows sand particles on the upper part of the piston 3 to enter the central axis position along the spiral flow channel and flow back into the working chamber. The spiral flow channel has a depth of 0.5mm-5mm and a width of 0.5mm-1mm, and is opened from the outside to the inside at the same depth or gradually deeper, which can effectively guide sand particles with a diameter of 50μm or more to flow back.

[0019] The number of piston rings 4 is not less than 3, and the piston rings 4 are provided with oblique openings to generate elastic deformation, thereby fitting tightly against the cylinder body 1.

[0020] The arrangement of the piston rings 4 depends on their number. Multiple piston rings 4 are evenly and staggered around the piston 3 to form a multi-level sealing defense.

[0021] The upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5 are separate structures, nested and installed in the annular grooves 7 at the upper and lower ends of the piston 3. The upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5 together form a separate sand-proof sealing ring.

[0022] The upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5 are molded from polytetrafluoroethylene (PTFE) material. They are nested and installed in the annular grooves 7 at both ends of the piston 3. The inclination angle between the upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5 and the inner wall of the cylinder 1 is controlled between 120° and 150°, forming a sand particle guiding channel.

[0023] Working principle: The piston body is equipped with a three-layer sealing structure: the first sealing structure is formed by the upper sand-proof sealing ring 2 fitting against the cylinder body 1; the second sealing structure is formed by the piston ring 4 fitting against the cylinder body 1; the third sealing structure is formed by the lower sand-proof sealing ring 5 fitting against the cylinder body 1. The piston 3 has an annular mounting groove in the radial direction to mate with the piston ring 4, and the piston ring 4 fits tightly against the cylinder body 1 to form the main sealing surface; the piston 3 has annular grooves 7 at its upper and lower ends to respectively install the upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5, forming a symmetrical sand-proof barrier.

[0024] The piston ring 4 described in this invention is made of surface-treated steel to ensure wear resistance under high sand content conditions. Wear-resistant fillers are added to the materials of the upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5 to improve resistance to sand impact.

[0025] The triple sealing structure of this invention forms a stepped sand-proof system: the first upper sand-proof sealing ring 2 intercepts large sand particles; the second piston ring 4 achieves the main seal; and the third lower sand-proof sealing ring 5 ensures zero leakage. Each sealing element works independently yet coordinates with each other.

[0026] The upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5 described in this invention are installed in a floating manner, which can automatically compensate for the gap changes caused by the deformation or eccentricity of the cylinder body 1 and maintain a stable sand-proof effect.

[0027] The piston 3 described in this invention has an overall length that is 40%-50% shorter than that of traditional designs. It achieves a compact design by optimizing the sealing layout, thereby reducing motion inertia and energy consumption.

[0028] Example 2, a sand-proof sealing method for a sand-proof sealing structure used in a submersible electric pump piston, comprising: The design utilizes a triple-sealing structure to form a stepped sand-proof system, creating a sand barrier. This allows sand particles to flow back into the working chamber under the action of the first sealing structure. The second sealing structure further seals any leaked oil, and the third sealing structure achieves zero leakage.

[0029] For example, the first sealing structure is formed by the upper sand-proof sealing ring 2 and the cylinder body 1; the second sealing structure is formed by the piston ring 4 and the cylinder body 1; and the third sealing structure is formed by the lower sand-proof sealing ring 5 and the cylinder body 1.

[0030] The piston 3 has an annular mounting groove in the radial direction to cooperate with the piston ring 4. The piston ring 4 and the cylinder 1 are tightly fitted to form the main sealing surface. The piston 3 has annular grooves 7 at the upper and lower ends to install the upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5, respectively, forming a symmetrical sand-proof barrier.

[0031] For example, the first sand-proof sealing ring 2 intercepts large sand particles.

[0032] An exemplary method for causing sand particles to flow back into the working chamber under the action of the first sealing structure includes: Step 1: Combining particle-liquid interaction, paper adhesion resistance, and particle characteristics, set the sliding angle of sand particles on the inclined surface of the upper sand-proof sealing ring 2 in the liquid-solid two-phase system; Slide angle Represented as: In the formula, The effective coefficient of friction includes both dry friction and the viscous effect of the liquid; It is a constant; For effective cohesion, including liquid bridging forces and van der Waals forces: In the formula, The internal friction angle of sand grains in their dry state. For crude oil dynamic viscosity, For sand particle density, The diameter of the sand grains. Shear rate (depends on flow conditions) This is the viscosity correction factor; Step 2: Substitute the sliding angle of the sand particles on the inclined surface of the upper sand-proof sealing ring 2 according to the sand-containing working conditions and calculate to obtain the actual working condition sliding angle, preferably about 60°; Step 3: Based on the obtained actual working condition sliding angle, set the angle between the upper surface of the upper sand-proof sealing ring 2 and the upper end face of the piston 3. Based on the set angle, obtain the inner inclined surface of the upper sand-proof sealing ring 2 near the axis of the piston 3. The set angle is 60°-90°. Step 4: Based on the inner inclined surface of the upper sand-proof sealing ring 2 near the axis of the piston 3, the resultant force of the sand particles being impacted by the oil and the reaction force of the upper sand-proof sealing ring 2 points towards the working chamber, thereby guiding the sand particles back into the working chamber.

[0033] Preferably, the inner inclined surface of the upper sand-proof sealing ring 2 near the axis is provided with a spiral flow channel, allowing sand particles on the upper part of the piston 3 to enter the central axis position along the spiral flow channel and flow back into the working chamber. The spiral flow channel has a depth of 0.5mm-5mm and a width of 0.5mm-1mm, and is opened from the outside to the inside at a constant or gradually increasing depth, which can effectively guide the backflow of sand particles with a diameter of 50μm or larger. The inner inclined surface of the upper sand-proof sealing ring 2 near the axis of the piston 3 is at an angle of 60°-90° to the upper end face of the piston 3. For example, the angle between the inner inclined surface of the upper sand-proof sealing ring 2 near the axis of the piston 3 and the inner wall of the cylinder 1 is controlled between 120° and 150°.

[0034] As can be seen from the above embodiments, the anti-sand sealing structure of the submersible electric pump piston proposed in this invention adopts a triple sealing structure composed of an upper anti-sand sealing ring 2, a piston ring 4, and a lower anti-sand sealing ring 5, forming a stepped anti-sand sealing system. The first anti-sand ring can intercept the main sand particles, the second piston ring realizes the main sealing function and works in a clean environment, and the third anti-sand ring serves as the final barrier to ensure zero sand leakage. The sand-proof sealing structure for the submersible electric pump piston proposed in this invention, through the coordinated arrangement of split retaining rings and multiple piston rings, shortens the piston length by 40-50% while ensuring the sealing effect, reduces the overall weight, and significantly reduces the moment of inertia and energy consumption. The sand-proof sealing structure of the submersible electric pump piston proposed in this invention has an inclination design of the sand-proof sealing ring to form a sand particle guiding channel, which can guide the intruding sand particles back to the working chamber and avoid accumulation. The sand-proof sealing structure of the submersible electric pump piston proposed in this invention features a split retaining ring design that facilitates quick replacement of damaged parts without disassembling the entire piston, thus shortening maintenance time. The sand-proof sealing structure of the submersible electric pump piston proposed in this invention features staggered piston rings, which can achieve pressure reduction and throttling. Simultaneously, when the piston reciprocates within the cylinder 1, each piston ring remains firmly against the cylinder wall under its own elastic force, forming multiple evenly distributed radial support points. This multi-point support structure effectively counteracts the piston's sway caused by lateral forces, maintains the coaxiality of the piston and cylinder, and provides support and alignment, ensuring stable operation of the equipment.

[0035] Application Example: Piston 3 forms a precision fit with piston ring 4 through a circumferential annular mounting groove. In its free state, piston ring 4 has an oblique opening. After installation, the opening gap is less than 1mm. Under its own elastic force, piston ring 4 adheres tightly to the inner wall of cylinder 1, blocking the gap between piston 3 and cylinder 1 and sealing the oil. Furthermore, considering that a small amount of oil may still leak from the opening of piston ring 4 and from the momentary contact between the two ends of piston ring 4 and the side walls of the annular mounting groove, multiple piston rings 4 are arranged in an alternating phase to achieve throttling and pressure reduction. Simultaneously, the upper and lower anti-sand sealing rings 2 and 5 are embedded in the piston 3 with an interference fit, preventing sand particles from entering the sealing rings, accelerating the wear of piston ring 4, and reducing the service life of the sealing structure. When the submersible pump is working, sand particles are first intercepted by the upper anti-sand sealing ring 2 and guided back to the working chamber along the oblique surface of the upper anti-sand sealing ring 2. Some oil leaks into the piston ring 4 area. The multiple piston rings 4 are tightly fitted to cylinder 1, preventing oil leakage.

[0036] Figure 2 for Figure 1 The three-dimensional model of the split-type sand-proof sealing ring is made of polytetrafluoroethylene (PTFE). After installation, the upper sand-proof sealing ring 2 forms a flow-guiding angle with the inner wall of the cylinder 1, allowing sand particles to flow back and no longer enter the piston ring 4 sealing structure. The upper sand-proof sealing ring 2 and the lower sand-proof sealing ring 5 have the same structure, but the lower sand-proof sealing ring 5 is installed on the lower part of the piston 3, which is the opposite of the installation method of the upper sand-proof sealing ring 2.

[0037] 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 modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A sand-proof sealing structure for a submersible electric pump piston, characterized in that, The structure includes a piston (3) and three sealing structures provided on the piston (3); the first sealing structure is an upper seal formed by the upper sand-proof sealing ring (2) fitting with the cylinder body (1); the second sealing structure is a main seal formed by the piston ring (4) fitting with the cylinder body (1); and the third sealing structure is a lower seal formed by the lower sand-proof sealing ring (5) fitting with the cylinder body (1). The piston (3) has annular grooves (7) at its upper and lower ends, where an upper sand-proof sealing ring (2) and a lower sand-proof sealing ring (5) are respectively installed. The upper sand-proof sealing ring (2) and the lower sand-proof sealing ring (5) are symmetrically installed at the upper and lower ends of the piston (3). The sand-proof sealing ring (2) has a spiral flow channel on the inner inclined surface near the axis, so that the sand particles on the upper part of the piston (3) enter the central axis position through the spiral flow channel and flow back into the working chamber. The spiral flow channel is opened from the outside to the inside at the same depth or gradually deeper.

2. The sand-proof sealing structure for a submersible electric pump piston according to claim 1, characterized in that, The piston (3) engages with the piston ring (4) in the radial direction through an annular mounting groove. The piston ring (4) fits tightly with the cylinder (1) to form a sealing surface, which is used to prevent oil leakage from the sealing surface.

3. The sand-proof sealing structure for a submersible electric pump piston according to claim 1, characterized in that, The number of piston rings (4) is not less than 3, and the piston rings (4) are provided with oblique openings. The multiple piston rings (4) are evenly staggered around the piston (3) to form a multi-level sealing defense line.

4. The sand-proof sealing structure for a submersible electric pump piston according to claim 1, characterized in that, The upper sandproof sealing ring (2) and the lower sandproof sealing ring (5) are molded from polytetrafluoroethylene material.

5. The sand-proof sealing structure for a submersible electric pump piston according to claim 1, characterized in that, The upper sand-proof sealing ring (2) and the lower sand-proof sealing ring (5) are installed in a floating manner. They are installed in the annular groove (7) between the ring and the piston (3) to maintain axial and radial movement gaps. When the cylinder (1) deforms due to temperature changes or pressure fluctuations, the ring moves freely in the groove and compensates for the gap change between the cylinder (1) and the piston (3) through its own displacement, thus avoiding hard jamming.

6. A sand-proof sealing method for a sand-proof sealing structure used in a submersible electric pump piston, characterized in that, This method is used to provide a sand-proof seal for the sand-proof sealing structure for the piston of a submersible electric pump as described in any one of claims 1-5, the method comprising: The design utilizes a triple-sealing structure to form a stepped sand-proof system, creating a sand barrier. This allows sand particles to flow back into the working chamber under the action of the first sealing structure. The second sealing structure further seals any leaked oil, and the third sealing structure achieves zero leakage.

7. The sand-proof sealing method for the sand-proof sealing structure of the submersible electric pump piston according to claim 6, characterized in that, The method for allowing sand particles to flow back into the working chamber under the action of the first sealing structure includes the following steps: Step 1: Combining particle-liquid interaction, paper adhesion resistance and particle characteristics, set the sliding angle of sand particles on the upper surface of the upper sand-proof sealing ring (2) in the liquid-solid two-phase system; Slide angle Represented as: ； In the formula, The effective coefficient of friction includes both dry friction and the viscous effect of the liquid; It is a constant; For effective cohesion, including liquid bridging forces and van der Waals forces: ； In the formula, The internal friction angle of sand grains in their dry state. For crude oil dynamic viscosity, For sand particle density, The diameter of the sand grains. Shear rate, This is the viscosity correction factor; Step 2: Substitute the sliding angle of the sand particles on the inclined surface of the upper sand-proof sealing ring (2) according to the sand-containing working conditions and calculate to obtain the actual working condition sliding angle; Step 3: Based on the obtained actual working condition sliding angle, set the upper surface of the upper sand-proof sealing ring (2) and the upper end face of the piston (3) at an angle, and obtain the inner inclined surface of the upper sand-proof sealing ring (2) near the axis of the piston (3) based on the set angle. Step 4: Based on the inner inclined surface of the upper sand-proof sealing ring (2) near the axis of the piston (3), the resultant force of the sand particles being impacted by the oil and the reaction force of the upper sand-proof sealing ring (2) points towards the working chamber, thereby guiding the sand particles back into the working chamber.

8. The sand-proof sealing method for the sand-proof sealing structure of the submersible electric pump piston according to claim 7, characterized in that, The actual sliding angle in step two is 60°. The included angle set in step three and the inner slope of the upper sand-proof sealing ring (2) near the piston (3) axis are 60°-90°.

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