Self-balancing axial force impeller device for centrifugal pump

Abstract

The self-balancing axial force impeller device for the centrifugal pump comprises an impeller body and a rear cover plate, at least one adjusting cavity extending in the radial direction is formed in the rear cover plate, a centrifugal balance weight sliding block is arranged in the adjusting cavity, and a radial guide limiting structure is arranged between the adjusting cavity and the centrifugal balance weight sliding block. An elastic reset structure is connected between the centrifugal balance weight sliding block and the inner side wall of the adjusting cavity, a balance flow channel is formed in the rear cover plate, an inlet of the balance flow channel is used for communicating with a high-pressure cavity in the back of the impeller rear cover plate, and an outlet of the balance flow channel is used for communicating with a low-pressure area at an impeller inlet. The effective through-flow area of the balance flow channel can be adjusted through the radial position of the centrifugal balance weight sliding block, when the rotating speed of the impeller changes, the radial position of the centrifugal balance weight sliding block changes in a self-adaptive mode, the discharge amount of the balance flow channel is correspondingly and continuously adjusted, and dynamic balance of the axial force of the impeller is achieved.

Description

Technical Field

[0001] This invention belongs to the field of centrifugal pump technology, specifically a self-balancing axial force impeller device for centrifugal pumps. Background Technology

[0002] Centrifugal pumps are among the most widely used fluid transport devices, and the axial force generated during their operation is a key factor affecting the reliability, efficiency, and lifespan of the equipment. Axial force is mainly generated by factors such as pressure asymmetry before and after the impeller and changes in fluid momentum. Unbalanced axial force can lead to thrust bearing overload, rotor axial movement, and mechanical seal failure, which in turn can cause increased vibration, higher energy consumption, and even equipment damage.

[0003] A search revealed Chinese invention patent CN117685231A, which discloses an improved axial force self-balancing centrifugal chemical pump. This design incorporates a sliding plate for an axially sliding piston behind the impeller. A transmission mechanism, including a transmission ring, gears, and a swing plate, converts fluid impact force into mechanical displacement, thereby dynamically changing the pressure in the sealed chamber behind the piston to provide dynamic support to the impeller back surface and balance the axial force. The design also integrates a temperature compensation device based on shape memory alloys to address the impact of operating temperature rise. However, it still has significant limitations: First, its balancing mechanism relies on multi-stage mechanical transmissions such as gears and connecting rods, resulting in a complex structure with extremely high requirements for machining and assembly precision. Long-term operation poses risks of wear and jamming, challenging its reliability. Second, the temperature compensation device introduces temperature-sensitive shape memory alloy components, whose performance stability is significantly affected by environmental and working medium temperatures, increasing system uncertainty. Finally, the entire balancing mechanism increases the pump's axial length and overall complexity, hindering compact pump design.

[0004] Therefore, existing technologies still lack a highly integrated axial force balancing solution that requires no complex external transmissions or temperature-sensitive elements, achieves full-condition self-adaptation entirely based on its own physical principles, and combines high reliability with compactness. Especially for applications with limited space, variable operating conditions, or high maintainability requirements, there is an urgent need for a novel, built-in, purely mechanical, and self-adaptive balancing device. Summary of the Invention

[0005] To address the problems mentioned in the background section, the present invention adopts the following technical solution.

[0006] A self-balancing axial force impeller device for a centrifugal pump includes an impeller body and a rear cover plate. The rear cover plate has at least one radially extending adjustment chamber inside, and a centrifugal counterweight slider is provided in the adjustment chamber. A radial guide and limiting structure is provided between the adjustment chamber and the centrifugal counterweight slider. An elastic reset structure is connected between the centrifugal counterweight slider and the inner sidewall of the adjustment chamber. The rear cover plate has a balancing flow channel. The inlet of the balancing flow channel is used to connect to the high-pressure chamber on the back of the impeller rear cover plate, and the outlet of the balancing flow channel is used to connect to the low-pressure area at the impeller inlet. The radial position of the centrifugal counterweight slider can adjust the effective flow area of ​​the balancing flow channel. When the impeller speed changes, the radial position of the centrifugal counterweight slider changes adaptively and continuously adjusts the discharge flow of the balancing flow channel accordingly to achieve dynamic balance of the axial force of the impeller.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Highly integrated structure and compact design: All balancing mechanisms of this invention, including the adjusting chamber, centrifugal counterweight slider, elastic reset structure, and balancing flow channel, are integrated inside the impeller rear cover plate, forming a single, integrated impeller device. This design internalizes the axial force balancing function, eliminating the need for separate balancing discs, piston cylinders, or other complex external components on the pump shaft system, significantly reducing the pump's axial dimension. This facilitates the miniaturization and compact design of centrifugal pump units, making them more suitable for applications with limited installation space.

[0008] 2. Achieves purely mechanical adaptive balancing with high reliability: This device relies entirely on the dynamic balance between the centrifugal force generated by the impeller rotation and the restoring force provided by the elastic reset structure to drive the centrifugal counterweight slider, thereby automatically adjusting the pressure relief flow rate of the balancing channel. The entire operation does not require any external sensors, control systems, actuators, or temperature-sensitive memory alloy components, and also eliminates the need for multi-stage gears, connecting rods, and other transmission mechanisms as described in the background section. This simplifies the system configuration, reduces the stringent requirements for machining and assembly precision, and reduces the risk of failure caused by wear, jamming, or electronic component failure in complex transmission pairs, thereby improving the operational reliability and long-term stability of the entire balancing system.

[0009] 3. Continuous adjustment across all operating conditions, dynamic optimization of balancing effect: The radial position of the centrifugal counterweight slider can be continuously and smoothly adaptively adjusted according to changes in impeller speed, thereby achieving precise and continuous adjustment of the effective flow area of ​​the balancing channel. This allows the pressure relief flow rate to match the changes in axial force generated by the impeller under different speed conditions in real time, achieving dynamic axial force balance across the entire operating range from low to high speed. Compared to traditional fixed balancing holes, this device can maintain a good axial force balance over a wider operating range, helping to reduce the load on the thrust bearing, reduce unit vibration, and extend equipment service life. Attached Figure Description

[0010] Figure 1 This is a three-dimensional structural diagram of the centrifugal pump in this invention.

[0011] Figure 2 This is a partial cross-sectional view of the centrifugal pump in this invention.

[0012] Figure 3 This is the three-dimensional structure of the impeller section of the centrifugal pump in this invention. Figure 1 .

[0013] Figure 4 This is the three-dimensional structure of the impeller section of the centrifugal pump in this invention. Figure 2 .

[0014] Figure 5 This is a schematic diagram of the internal structure of the rear cover plate in this invention.

[0015] In the figure, 1 is the impeller body; 2 is the rear cover plate; 3 is the regulating chamber; 4 is the centrifugal counterweight slider; 5 is the radial guide limiting structure; 6 is the elastic reset structure; and 7 is the balance flow channel. Detailed Implementation

[0016] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0017] It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0018] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0019] like Figures 1-5As shown, a self-balancing axial force impeller device for a centrifugal pump according to the present invention includes an impeller body 1 and a rear cover plate 2. The rear cover plate 2 has at least one radially extending adjustment cavity 3 inside, and a centrifugal counterweight slider 4 is provided in the adjustment cavity 3. A radial guide limiting structure 5 is provided between the adjustment cavity 3 and the centrifugal counterweight slider 4. An elastic reset structure 6 is connected between the centrifugal counterweight slider 4 and the inner sidewall of the adjustment cavity 3. The rear cover plate 2 has a balancing flow channel 7. The inlet of the balancing flow channel 7 is used to connect to the high-pressure cavity on the back of the impeller rear cover plate 2, and the outlet of the balancing flow channel 7 is used to connect to the low-pressure area at the impeller inlet. The radial position of the centrifugal counterweight slider 4 can adjust the effective flow area of ​​the balancing flow channel 7. When the impeller speed changes, the radial position of the centrifugal counterweight slider 4 changes adaptively and the discharge flow of the balancing flow channel 7 is adjusted accordingly to achieve dynamic balance of the axial force of the impeller.

[0020] In this structure, when the centrifugal pump starts and runs, the impeller body 1 begins to rotate under the drive shaft. This rotational motion causes the centrifugal counterweight slider 4 in the adjustment chamber 3 of the rear cover plate 2 to be subjected to centrifugal force. This centrifugal force drives the centrifugal counterweight slider 4 to overcome the restoring force provided by the elastic reset structure 6, pointing towards the impeller axis, and move outward along the constraint direction of the radial guide limit structure 5, that is, strictly along the radial direction of the impeller. The higher the speed of the impeller, the greater the centrifugal force generated, and the greater the radial distance that the centrifugal counterweight slider 4 moves after overcoming the restoring force. The radial position of the centrifugal counterweight slider 4 is directly related to and determines the effective flow area of ​​the balance flow channel 7. As the slider moves outward, the flow area of ​​the balance flow channel 7 changes accordingly. Specifically, the flow area usually increases as the centrifugal counterweight slider 4 moves outward. The inlet of the balance flow channel 7 is connected to the high-pressure chamber on the back of the impeller rear cover plate 2, and the outlet is connected to the low-pressure area at the impeller inlet. When the flow area of ​​the balancing channel 7 changes due to the displacement of the slider, the fluid flow rate from the high-pressure chamber to the low-pressure zone through the balancing channel 7 is continuously and adaptively adjusted. This purely mechanical adjustment dynamically adjusts the pressure in the high-pressure chamber on the back of the impeller. The adjustment direction is to counteract the fluctuations in the impeller's axial force caused by changes in speed and operating conditions, thereby balancing the net axial force acting on the impeller, which helps reduce the load on the thrust bearing and improves the stability of pump operation. In summary, this structure realizes a built-in, adaptive axial force balancing mechanism. Its core lies in using the centrifugal force generated by the pump itself during operation as a feedback signal to directly adjust the pressure relief channel through mechanical linkage, without the need for external sensors or control systems.

[0021] In one embodiment, the adjustment cavity 3 is a plurality of segmented independent cavities arranged circumferentially, or a continuous annular sealed cavity.

[0022] In this structure, the structural design of the regulating cavity 3 provides two optional implementation schemes to adapt to different design requirements, manufacturing processes, or performance focuses.

[0023] Option 1: Multiple segmented independent cavities evenly arranged circumferentially In this design, multiple independent chambers are uniformly machined along the circumference inside the rear cover plate 2. Each chamber extends radially but is spaced apart circumferentially. Each independent chamber typically houses a centrifugal counterweight slider 4, a set of radial guide and limiting structures 5, and a corresponding elastic reset structure 6. The advantages of this "segmented" design are: structural independence and reliability: each chamber-slider assembly works independently. If one set of components fails due to foreign object jamming or other reasons, the remaining components can still continue to provide partial balancing function, and the system has a certain degree of redundancy.

[0024] Option 2: Continuous annular sealed cavity In this design, a complete annular cavity surrounding the center of the pump shaft is machined inside the rear cover plate 2. This annular cavity has a consistent depth in the radial direction, forming a continuous sealed space. Multiple centrifugal counterweight sliders 4 can be arranged circumferentially along this annular cavity and slide within it. This "continuous" design provides the sliders with an uninterrupted sliding track, making the slider movement smoother, especially in situations where multiple sliders need to work together to cover the entire circumference to adjust an annular throttling gap.

[0025] In one embodiment, the radial guide limiting structure 5 is a guide groove, guide key, or linear guide rail structure, which constrains the centrifugal counterweight slider 4 to only be able to move linearly along the impeller radial direction.

[0026] In this structure, the core function is to establish a precise, single-degree-of-freedom motion constraint to ensure that the centrifugal counterweight slider 4 can only perform linear reciprocating motion along the radial direction of the impeller when subjected to force, while effectively limiting any displacement or rotation in the circumferential and axial directions.

[0027] Specifically, the three structural forms and their implementation methods are as follows: Guide groove: A radially extending groove is directly machined into the inner wall of the adjusting cavity 3. Correspondingly, a matching protrusion is provided on the side of the centrifugal counterweight slider 4. The sliding pair is formed by the engagement of the protrusion with the groove. This solution has a compact structure and high integration, and is a common method for achieving guidance directly on the impeller casting or machined parts, suitable for designs with stringent space requirements.

[0028] Guide key: Keyways are machined on the inner wall of the adjustment cavity 3 and the centrifugal counterweight slider 4, respectively, and the movement of the two is coupled by a rectangular or semi-circular flat key. This solution has good guiding rigidity, can withstand large lateral forces, and the key is a standard part, which may facilitate replacement after wear under specific design conditions.

[0029] Linear guide structure: Employs more precise linear motion components, such as miniature linear bearings, ball bearings, or their integrated modules. This solution offers extremely low motion friction resistance, high motion accuracy, and smoothness, making it particularly suitable for high-speed centrifugal pumps or precision applications requiring extremely high slider response sensitivity and long-term jam-free operation.

[0030] In one embodiment, the elastic reset structure 6 is an elastic diaphragm, an elastic bellows, or a fluid-damped elastomer.

[0031] In this structure, the core function is to provide a stable, predictable, and directional restoring force or resistance to the centrifugal counterweight slider 4, pointing towards the impeller shaft.

[0032] Specifically, the three structural forms are as follows: Elastic diaphragms: These are typically made of heat-treated spring steel, stainless steel, or high-performance engineering plastic sheets. They generate elastic restoring force through their own bending and flexural deformation. Their main characteristics are an extremely flat structure that adds almost no axial dimension to the device, and the absence of sliding friction parts during operation, resulting in theoretically minimal wear.

[0033] Elastic bellows: A tubular metal (such as phosphor bronze or stainless steel) component with precision axial corrugations. Elastic force is provided by compressing or stretching the corrugations axially. Its main characteristic is the ability to provide near-linear elastic force over a large displacement stroke, with easily predictable performance curves. Simultaneously, its own sealed cavity structure naturally isolates the regulating chamber 3 containing the slider from the pumping medium, making it suitable for applications with special requirements for cavity sealing.

[0034] Fluid-damped elastomer: This structure may contain a sealed cavity pre-filled with gas (such as nitrogen) or incompressible liquid, and connected to a slider via a piston or flexible bladder. As the slider moves, it compresses the fluid, using fluid pressure to provide a restoring force. Simultaneously, the viscous resistance generated by the fluid flowing through designed orifices or gaps provides a significant damping effect. Its main feature is the integration of restoring and damping, effectively suppressing oscillations that may occur when the slider experiences sudden changes in speed or is subjected to fluid pulsation, resulting in a smoother dynamic response of the system.

[0035] In one embodiment, the balance channel 7 is a wedge-shaped throttling slot, a gradually changing throttling surface, or a stepped throttling orifice, so that the radial displacement of the centrifugal counterweight slider 4 can continuously adjust the effective flow area of ​​the balance channel 7.

[0036] In this structure, the core objective is to accurately and continuously convert the radial linear displacement of the centrifugal counterweight slider 4 into a change in the effective flow area of ​​the balance channel 7, thereby achieving linear or predictable regulation of the pressure relief flow rate.

[0037] Specifically, the three throttling structures are as follows: Wedge-shaped throttling slot: Its flow cross-section is a wedge-shaped groove whose width or height varies radially. When the centrifugal counterweight slider 4 moves radially, the relative position of its edge with respect to this wedge-shaped slot changes, causing the "minimum cross-sectional area" size through which the fluid passes to change continuously. The main feature is that the displacement of the slider and the change in the flow area are usually linear or approximately linear, resulting in smooth and predictable control characteristics, which is beneficial for achieving fine flow regulation.

[0038] Gradual throttling surface: This design typically involves the fit between a specially profiled flow channel wall and a corresponding profile on the slider. As the slider moves radially, the gap between the two profiles (i.e., the flow channel) increases or decreases uniformly. The key feature is that the functional relationship between the flow area and the slider displacement can be "customized" by changing the profile curve, thereby optimizing the system's balanced response characteristics across different speed ranges and achieving a more ideal dynamic match.

[0039] A stepped flow orifice consists of a series of radially arranged holes or slots of increasing or decreasing size. As the slider moves, it sequentially covers or exposes these orifices. Although the opening / closing of a single orifice is binary, near-continuous flow area adjustment can be achieved by densely arranging multiple small steps and designing the slider edge to simultaneously cover multiple steps. Its main advantage is that it balances ease of design and fabrication with continuous adjustment; by optimizing the size and distribution of the steps, the desired adjustment curve can be approximated.

[0040] In one embodiment, the outlet end of the balance flow channel 7 is provided with a flow stabilizing and guiding structure, which directs the pressure relief fluid into the impeller inlet, reduces inlet disturbance, and improves the impeller's cavitation resistance.

[0041] This structure incorporates an additional fluid optimization design, primarily aimed at guiding and shaping the fluid draining from the balancing channel 7, directing it into the low-pressure zone at the impeller inlet in a manner more conducive to the main flow path. The pressure-relief fluid exiting the balancing channel 7 typically exhibits high velocity and potentially turbulent flow direction; if it were to directly and disorderly impact or mix into the mainstream flow at the impeller inlet, it could have adverse effects.

[0042] In one embodiment, the centrifugal counterweight slider 4 is a modular replaceable mass block, which can be adapted to different head, speed and medium conditions by changing sliders of different masses.

[0043] In this structure, the mass of the centrifugal counterweight slider 4 is one of the core parameters determining the dynamic response of the entire self-balancing system. According to the principles of physics, the centrifugal force (F_c) generated by the slider during rotation is proportional to the square of its mass (m), radius of rotation (r), and angular velocity (ω) (F_c = m * ω² * r). Therefore, at the same rotational speed and radial position, sliders of different masses will generate centrifugal forces of different magnitudes.

[0044] In one embodiment, the centrifugal counterweight slider 4 and the adjusting chamber 3 are magnetically coupled non-contactly coupled, with no mechanical friction or wear, which is suitable for high-speed centrifugal pumps and working conditions containing particulate media.

[0045] This structure abandons the traditional mechanical contact guiding and resetting structure, instead utilizing magnetic force to achieve key functions. Since there is no physical contact between the slider and the cavity, it fundamentally avoids material wear, heat generation, and the resulting performance degradation or jamming risks caused by solid friction. This greatly improves the reliability of the device during long-term operation, especially at high speeds.

[0046] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A self-balancing axial force impeller device for a centrifugal pump, comprising an impeller body (1) and a rear cover plate (2), characterized in that: The rear cover plate (2) has at least one radially extending adjustment cavity (3) inside. The adjustment cavity (3) is provided with a centrifugal counterweight slider (4). A radial guide limiting structure (5) is provided between the adjustment cavity (3) and the centrifugal counterweight slider (4). An elastic reset structure (6) is connected between the centrifugal counterweight slider (4) and the inner sidewall of the adjustment cavity (3). The rear cover plate (2) has a balance flow channel (7). The inlet of the balance flow channel (7) is used to connect to the high pressure cavity on the back of the impeller rear cover plate (2). The outlet of the balance flow channel (7) is used to connect to the low pressure area at the impeller inlet. The radial position of the centrifugal counterweight slider (4) can adjust the effective flow area of ​​the balance flow channel (7). When the impeller speed changes, the radial position of the centrifugal counterweight slider (4) changes adaptively and the discharge flow of the balance flow channel (7) is adjusted accordingly to achieve dynamic balance of the axial force of the impeller.

2. The self-balancing axial force impeller device for centrifugal pumps according to claim 1, characterized in that: The adjustment cavity (3) is a plurality of segmented independent cavities arranged evenly in the circumference, or a continuous annular sealed cavity.

3. The self-balancing axial force impeller device for centrifugal pumps according to claim 1, characterized in that: The radial guide limiting structure (5) is a guide groove, guide key or linear guide rail structure, which constrains the centrifugal counterweight slider (4) to only be able to move in a straight line along the impeller radial direction.

4. The self-balancing axial force impeller device for centrifugal pumps according to claim 1, characterized in that: The elastic reset structure (6) is an elastic diaphragm, an elastic bellows, or a fluid damping elastomer.

5. The self-balancing axial force impeller device for centrifugal pumps according to claim 1, characterized in that: The balance channel (7) is a wedge-shaped throttling slot, a gradually changing throttling surface, or a stepped throttling orifice, so that the radial displacement of the centrifugal counterweight slider (4) can continuously adjust the effective flow area of ​​the balance channel (7).

6. The self-balancing axial force impeller device for a centrifugal pump according to claim 1, characterized in that: The outlet end of the balanced flow channel (7) is provided with a flow stabilizing and guiding structure, which directs the pressure relief fluid into the impeller inlet, reduces inlet disturbance and improves the impeller's cavitation resistance.

7. The self-balancing axial force impeller device for a centrifugal pump according to claim 1, characterized in that: The centrifugal counterweight slider (4) is a modular replaceable mass block, which can be adapted to different head, speed and medium conditions by changing sliders of different masses.

8. The self-balancing axial force impeller device for a centrifugal pump according to claim 1, characterized in that: The centrifugal counterweight slider (4) and the regulating chamber (3) are magnetically coupled and non-contact, with no mechanical friction or wear, and are suitable for high-speed centrifugal pumps and working conditions containing particulate media.

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