Adaptive seal structure for multi-stage centrifugal pump

Abstract

The self-adaptive sealing structure of the multistage centrifugal pump features an impeller inlet section that passes through a through-hole in the pump cover / partition. A sealing cavity is formed between the inner wall of the through-hole and the outer wall of the inlet section, containing a self-aligning floating ring. A tiny gap exists between the inner diameter of the floating ring and the outer surface of the impeller inlet section, and another tiny gap exists between the outer diameter of the floating ring and the inner wall of the sealing cavity. By incorporating a floating ring in the pump cover / partition and creating a tiny gap with the outer diameter of the impeller inlet, the floating ring automatically adjusts its position according to shaft movement and pressure changes, achieving self-alignment under the influence of fluid and impeller rotation. This results in highly efficient interstage sealing, effectively reducing interstage leakage and improving pump efficiency.

Description

Technical Field

[0001] This utility model relates to the field of centrifugal pumps, specifically an adaptive sealing structure for a multi-stage centrifugal pump. Background Technology

[0002] In multistage centrifugal pumps, the interstage seals located between the stages are crucial for preventing excessive leakage of high-pressure fluid into low-pressure areas and ensuring pump efficiency. Currently, the most common interstage seal structure is the fixed sealing ring. The fixed sealing ring is pressed into the inner bore of the intermediate stage, maintaining a fixed, minute gap with the impeller.

[0003] However, this type of seal has significant drawbacks: during pump operation, due to factors such as machining errors of parts and rotor weight, the pump shaft will experience a certain degree of deflection and radial runout. A fixed-gap sealing structure cannot adapt to this deviation and dynamic change, easily leading to a gap that is too small on one side, causing frictional wear, or even excessive offset causing the impeller and sealing ring to seize, while on the other side it is too large, exacerbating leakage. Once this localized contact wear occurs, the gap becomes uneven, the sealing effect rapidly declines, and internal leakage of the pump increases sharply, significantly reducing the high-pressure performance of the multistage centrifugal pump. Summary of the Invention

[0004] This invention addresses the shortcomings of existing fixed sealing rings in multi-stage centrifugal pumps by providing an adaptive sealing structure for multi-stage centrifugal pumps.

[0005] To achieve the above objectives, the technical solution adopted in this utility model includes a pump body comprising a pump cover and several intermediate sections, each of which is equipped with an impeller, and all impellers are driven to rotate by a shaft; adjacent intermediate sections are separated by a partition. The liquid inlet of the impeller passes through a through hole in the pump cover / partition, and a sealing cavity is provided between the inner wall of the through hole and the outer wall of the liquid inlet, and a self-aligning floating ring is provided in the sealing cavity; a small gap is provided between the inner diameter of the floating ring and the outer side of the liquid inlet of the impeller, and another small gap is provided between the outer diameter of the floating ring and the inner wall of the sealing cavity.

[0006] It also includes a floating ring support, the inner wall of which forms a sealed cavity with one end face of the through hole.

[0007] The pump cover / diaphragm through hole has a fixed ring extending axially at its edge; the floating ring bracket has an L-shaped cross section, with one side of the L-shape fixed to the outer wall of the fixed ring and the other side of the L-shape bent and extended radially toward the impeller; the end face of the fixed ring and the inner walls of the two sides of the L-shape of the floating ring bracket form a sealing cavity.

[0008] The retaining ring is located on the end face of the pump cover / partition on the side facing away from the liquid inlet direction.

[0009] The floating ring is made of PTFE non-metallic material with an extremely low coefficient of friction.

[0010] The micro-gap is less than 0.5 mm.

[0011] The floating ring floats freely in the radial direction within a tiny gap inside the sealed cavity, automatically adapting to the radial runout of the impeller and the deflection of the shaft.

[0012] Compared with existing technologies, this invention achieves efficient interstage sealing by setting a floating ring in the pump cover / partition and forming a small gap with the outer diameter of the impeller inlet. The floating ring can automatically adjust its position with the movement of the shaft and pressure changes, and achieve self-alignment under the action of fluid and impeller rotation, effectively reducing interstage leakage and improving pump efficiency.

[0013] The adaptive floating of the floating ring can also avoid wear, and its simple and reliable structure simplifies the structure and installation steps; the sealing performance can be improved by optimizing existing components, making it suitable for multi-stage centrifugal pumps. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model; Figure 2 This is a schematic diagram of the floating ring assembly structure according to an embodiment of the present invention. Figure 3 A structural breakdown diagram of the pump cover, intermediate section, impeller, floating ring, and floating ring support; Figure 4 This is a schematic diagram of the floating ring structure; Figure 5 This is a schematic diagram of the floating ring support structure; See attached diagram: 1. Pump cover, 2. Guide bearing, 3. Key, 4. Nut, 5. Floating ring, 6. Floating ring bracket, 7. Impeller, 8. O-ring, 9. Intermediate section, 10. Shaft sleeve, 11. Pump body, 12. Shaft. Detailed Implementation

[0015] The present invention will now be further described with reference to the accompanying drawings.

[0016] See Figures 1 to 5 , Figures 1 to 5 This illustration shows one embodiment of the present invention. The centrifugal pump body of this embodiment includes a pump cover and four intermediate sections, each with an impeller housed within its inner cavity. The connection between the pump cover and the first intermediate section is sealed with an O-ring, and subsequent adjacent intermediate sections are separated by partitions. The impellers are coaxially arranged. The shaft passes vertically through the through holes in the middle of each partition and the pump cover. The impeller is driven by the shaft via a key on its outer wall, which drives the shaft sleeve, thereby causing the impeller fixed to the shaft sleeve to rotate circumferentially. The front end of the shaft is rotatably connected to the pump cover via a guide bearing, and the front end of the shaft sleeve is fixed and limited by a nut.

[0017] The side of the impeller facing the direction of the input liquid is the inlet section, which has a water inlet. The entire inlet section is placed in a through hole. A sealing cavity is formed between the rear opening of the pump cover, the inner wall of the baffle through hole, and the outer wall of the inlet section. A floating ring is installed in the sealing cavity. There is a small gap between the inner diameter of the floating ring and the outer side of the impeller inlet section, and another small gap between the outer diameter of the floating ring and the inner wall of the sealing cavity.

[0018] Further, see Figure 2 The rear opening of the pump cover and the edge of the through hole of the partition are provided with retaining rings that extend axially / are thickened, and the retaining rings are all located on the end face of the pump cover / partition facing away from the liquid inlet direction. See also Figure 5 It also includes a floating ring support, which is circular in shape with an L-shaped cross-section. See also Figure 2 The first side of the L-shape is fixedly installed on the radial outer wall of the fixing ring, while the second side of the L-shape is bent radially toward the impeller and extends to the outer wall of the impeller inlet section (without contact).

[0019] Based on the aforementioned configuration, a sealing cavity is formed between the annular end face of the fixed ring facing the liquid inlet direction and the inner walls of the first and second sides of the L-shaped cross-section of the floating ring support. The sealing cavity has an opening facing the impeller, and the inner diameter of the floating ring extends from this opening, forming a small gap that is essentially in contact with the outer wall of the impeller. Meanwhile, a clearance fit is formed between the outer diameter of the floating ring and the inner wall of the first side of the L-shape. These two small gaps ensure that the floating ring makes slight floating / alignment within the sealing cavity, automatically adapting to the radial runout of the impeller and the deflection of the shaft, maintaining uniform gaps, and improving sealing performance.

[0020] Preferably, the micro-gap is less than 0.5 mm.

[0021] As a preferred option, the floating ring is made of PTFE non-metallic material with an extremely low coefficient of friction, which is lightweight; and it can reduce the friction between the impeller and the floating ring, making the floating ring less prone to wear and with a long service life.

[0022] After installation in this embodiment, even if there is a certain radial offset in the shaft, the impeller mounted on the shaft and the sealing ring will always be in contact with the outer wall of the impeller's inlet section due to the slight radial movement of the floating ring. The impeller can utilize the above working principle to compensate for the misalignment between the impeller and the floating ring caused by machining and assembly errors by floating through the micro-gap within the floating ring support, ensuring that the impeller and floating ring will not seize up during equipment operation. During equipment operation, when the impeller rotates at high speed, the outer wall of its inlet section will generate slight friction with the inner diameter of the floating ring, pushing the floating ring to make radial adaptive movement, ultimately compensating for the coaxiality deviation between the two and reaching an adaptive stable state.

[0023] The small gap setting meets the requirements for the rotational clearance between the floating ring and the impeller, without generating excessive frictional losses; it also prevents the impeller and the floating ring from seizing up, reduces leakage losses in the centrifugal pump, and improves the high-pressure performance of the engine.

[0024] The embodiments of this utility model have been described above with reference to the accompanying drawings and examples. The structures given in the embodiments do not constitute a limitation on this utility model. Those skilled in the art can make adjustments as needed, and various modifications or variations within the scope of the appended claims are all within the scope of protection.

Claims

1. An adaptive sealing structure for a multi-stage centrifugal pump, the pump body comprising a pump cover and several intermediate sections, each intermediate section containing an impeller; adjacent intermediate sections are separated by partitions, characterized in that: The impeller's inlet section passes through the through hole of the pump cover / partition. A sealing cavity is provided between the inner wall of the through hole and the outer wall of the inlet section. A self-aligning floating ring is provided in the sealing cavity. A tiny gap is provided between the inner diameter of the floating ring and the outer side of the impeller inlet, and another tiny gap is provided between the outer diameter of the floating ring and the inner wall of the sealing cavity. It also includes a floating ring support, the inner wall of which forms a sealed cavity with the end face of the through hole.

2. The adaptive sealing structure of the multi-stage centrifugal pump according to claim 1, characterized in that: The edge of the pump cover / diaphragm through hole is provided with a retaining ring that extends axially. The floating ring support has an L-shaped cross-section. One side of the L-shape is fixed to the outer wall of the fixed ring, and the other side of the L-shape is bent and extended radially toward the impeller. The end face of the fixed ring and the inner walls of the two L-shaped sides of the floating ring bracket form a sealed cavity.

3. The adaptive sealing structure of the multi-stage centrifugal pump according to claim 2, characterized in that: The retaining ring is located on the end face of the pump cover / baffle on the side facing away from the liquid inlet direction.

4. The adaptive sealing structure of the multi-stage centrifugal pump according to claim 1, characterized in that: The floating ring is made of PTFE non-metallic material.

5. The adaptive sealing structure of the multi-stage centrifugal pump according to claim 1, characterized in that: The micro-gap is less than 0.5 mm.

6. The adaptive sealing structure according to claim 1, characterized in that: The floating ring floats freely in the radial direction within the tiny gap inside the sealed cavity, automatically adapting to the radial runout of the impeller and the deflection of the shaft.

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