Leakage-free magnetic force driving self-suction vacuum pump

Abstract

This invention relates to the field of self-priming pump technology and discloses a leak-free magnetically driven self-priming vacuum pump, comprising a pump chamber, an inlet, an outlet, and an exhaust port. The pump chamber is a cavity for housing an impeller assembly and is connected to the inlet, outlet, and exhaust port. The impeller assembly is driven magnetically by a motor. The impeller assembly in the pump chamber includes a main impeller and an auxiliary impeller, which are coaxially arranged and facing opposite directions. The main impeller faces the inlet located at the front end of the pump chamber, and the auxiliary impeller faces the outlet located at the rear end of the pump chamber. An annular diffuser cavity is provided outside the main impeller, and a diffuser channel with a gradually increasing cross-section is provided in the diffuser cavity. A guide block is provided between the main impeller and the auxiliary impeller, and the blades of the auxiliary impeller are backward-curved blades.

Description

Technical Field

[0001] This invention relates to the field of self-priming pump technology, specifically a leak-free magnetically driven self-priming vacuum pump. Background Technology

[0002] A self-priming pump is a centrifugal pump with a unique "self-priming" capability. Its core value lies in its ability to automatically expel air from the pump body and suction pipe, thus automatically drawing up liquid below the pump level and putting it into normal operation without the need for external priming or auxiliary vacuum devices. This contrasts sharply with ordinary centrifugal pumps, which require the pump chamber and inlet pipe to be completely filled with liquid before startup; otherwise, the idling impeller cannot establish the necessary vacuum, resulting in failure to pump water or even damage to the equipment. The key to the self-priming pump's ability to achieve this function lies in its ingenious pump chamber structure design. Typically, its pump chamber volume is deliberately increased, integrating special structures such as a gas-liquid separation chamber and a return channel. In the initial startup phase, the pump chamber contains only air. The high-speed rotation of the impeller violently mixes the air with the small amount of pre-stored liquid in the pump body, forming a gas-liquid mixture. This mixture is then thrown towards the large-volume gas-liquid separator at the edge of the pump chamber. Upon exiting the chamber, due to the sudden drop in flow velocity and spatial expansion, the kinetic energy of the mixture is converted into potential energy. The liquid, with a density much greater than that of the gas, settles under the influence of gravity and returns to the impeller inlet through the return hole to participate in the next mixing cycle. Meanwhile, the separated gas is continuously compressed under the continuous action of the impeller and is eventually discharged from the pump through the exhaust port. This cycle repeats continuously, forming an efficient "exhaust-mixing-separation" internal loop, much like a built-in miniature vacuum system. It gradually "replaces" the air in the pump and inlet pipe until a sufficient vacuum is formed at the inlet, driving the downstream liquid to be continuously drawn in under atmospheric pressure. This completes the self-priming process and smoothly transitions to the normal working state of pure liquid transportation. For this reason, self-priming pumps play an irreplaceable role in scenarios such as farmland irrigation, municipal drainage, fire emergency response, and chemical transportation, where frequent starts are required or the suction inlet is below the liquid surface.

[0003] In the initial exhaust stage, existing self-priming pumps, due to the compressibility and low density of the gas, rely on a single-stage impeller, which acts like an inefficient fan, making it difficult to establish an effective pressure gradient. This results in slow or even failed self-priming startup and renders them ineffective in high-gas-content conditions. Secondly, during the gas-liquid mixing stage, the flow channel design is often not optimized, leading to incomplete gas-liquid separation. This can cause "gas resistance" or "dead zones" at the rear of the pump chamber, prolonging self-priming time and causing performance fluctuations and severe vibrations. Furthermore, pump chambers designed to achieve self-priming capabilities often result in a loose overall structure and excessively long axial dimensions. The enormous axial force generated by the impeller heavily relies on the thrust bearing, affecting the pump's compactness, lifespan, and reliability. Finally, once the water delivery stage begins, the single-impeller structure has limited head, making it difficult to balance self-priming performance with high head requirements. Summary of the Invention

[0004] (I) Technical problem to be solved: In view of the shortcomings of the existing technology, the present invention provides a leakage-free magnetic drive self-priming vacuum pump with the advantages of high self-priming performance and high head, and solves the problem of dead zone easily forming in the pump chamber.

[0005] (II) Technical Solution: To achieve the above-mentioned self-priming performance and high head, the present invention provides the following technical solution: a leak-free magnetically driven self-priming vacuum pump, comprising a pump chamber, an inlet, an outlet, and an exhaust port. The pump chamber is a cavity for housing an impeller assembly and is connected to the inlet, outlet, and exhaust port. The impeller assembly is driven by a motor magnetically. The impeller assembly in the pump chamber is provided with a main impeller and an auxiliary impeller. The main impeller and the auxiliary impeller are coaxially arranged and face opposite directions. The main impeller faces the inlet located at the front end of the pump chamber, and the auxiliary impeller faces the outlet located at the rear end of the pump chamber. An annular diffuser cavity is provided outside the main impeller. The diffuser cavity is provided with a diffuser channel with a gradually increasing cross-section. A guide block is provided between the main impeller and the auxiliary impeller. The blades of the auxiliary impeller are backward-curved blades.

[0006] The guide block is frustum-shaped, with the front diameter being the same as that of the diffuser cavity and the rear diameter being the same as that of the auxiliary impeller.

[0007] The guide block has a conical spiral guide groove on its side.

[0008] The connection between the outlet and the pump chamber is located above the axis of the pump chamber, and the channel is set at a right angle upwards.

[0009] The cross-section at the tail end of the pump chamber gradually decreases and contracts.

[0010] The inner wall of the pump chamber has rounded corners.

[0011] The width of the diffuser channel in the upper half of the diffuser cavity is greater than the width of the diffuser channel in the lower half.

[0012] The diameter ratio of the secondary impeller to the main impeller is 1.1.

[0013] (III) Beneficial Effects: Compared with the prior art, the present invention provides a leak-free magnetically driven self-priming vacuum pump with the following beneficial effects: 1. The leak-free magnetically driven self-priming vacuum pump, through the coaxially arranged main and auxiliary impellers in opposite directions, forms a "pull-pull-push" synergistic effect during the self-priming stage, which can quickly establish an effective pressure gradient in the pump cavity, significantly shorten the self-priming time and improve the ability to handle fluids with high gas content; when a small amount of liquid enters, the main impeller acts as a high-efficiency stirrer to vigorously mix the gas and liquid, and the resulting mixture achieves a rapid drop in flow velocity and preliminary gas-liquid separation in the unique annular diffuser cavity, while the auxiliary impeller further compresses and directionally pushes the separated gas, effectively preventing gas stagnation and eddy formation, and ensuring gas... The continuous and smooth discharge of fluids through this dual-power system greatly optimizes the gas-liquid mixing and separation cycle. Upon entering the pure water delivery stage, the main and auxiliary impellers work in series to form a two-stage centrifugal booster, jointly increasing the total head to meet higher head application requirements. Simultaneously, their back-to-back installation method cancels out the axial forces they generate, significantly reducing the load on the thrust bearing and improving the reliability and service life of the magnetic drive system. Furthermore, this structure offers implicit advantages such as smoother operation, lower vibration and noise, greater adaptability to operating conditions, and longer maintenance intervals. Combined with the absolute leak-free safety guarantee provided by the magnetic drive itself, this constitutes a highly efficient, reliable, durable, and widely applicable fluid transport device.

[0014] 2. This leak-free magnetically driven self-priming vacuum pump, through precise matching of the front and rear diameters of the diffuser chamber and the auxiliary impeller, and supplemented by a conical spiral guide groove, forms an extremely smooth and streamlined energy transfer channel from the main impeller to the auxiliary impeller. This design efficiently guides the fluid (whether a gas-liquid mixture or a pure liquid) after pressurization by the main impeller and initial stabilization in the diffuser chamber to the inlet of the auxiliary impeller with minimal impact and energy loss, significantly reducing eddies, impact losses, and vibration noise caused by abrupt changes in the flow channel in traditional structures. Its ingenious width design (10%-15% of the outer diameter of the main impeller) ensures structural strength and flow guidance while minimizing the axial clearance between the main and auxiliary impellers. This not only directly This design reduces the overall size and manufacturing cost of the pump chamber, achieving miniaturization and compactness of the equipment. Furthermore, by shortening the fluid transition path, it reduces mixing and friction losses within the gaps, thereby improving interstage transfer efficiency. The conical spiral guide channel itself exerts a positive constraint and rectification effect on the fluid, forcing it to move in a spiral motion along a predetermined trajectory. This further promotes more uniform mixing or more thorough separation of gas and liquid (depending on the operating conditions) and creates ideal inlet flow field conditions for the efficient work of the subsequent secondary impeller, allowing the secondary impeller to more fully perform its functions of gas compression or secondary pressurization. In addition, this structure also brings implicit advantages such as improved rotor component rigidity and overall operational stability, and reduced maintenance frequency. In summary, although the guide block has a compact structure, it is the core hub for connecting and optimizing the dual operating modes of the main and secondary impellers, playing an indispensable role in improving the overall efficiency, operational stability, and space compactness of the pump.

[0015] 3. This leak-free magnetically driven self-priming vacuum pump employs an asymmetrical flow channel design—wider at the top and narrower at the bottom—within its diffuser chamber. The wider upper flow channel provides ample space for gas expansion and ascent, acting like a high-speed gas highway, allowing it to flow unimpeded to the exhaust area and significantly reducing gas flow resistance. The relatively narrow lower flow channel maintains a higher liquid velocity, which not only enhances the liquid seal effect of the liquid returning from the reflux port on the main impeller, preventing gas short-circuiting, but also effectively flushes the flow channel, preventing impurity deposition and ensuring high efficiency. The pump maintains smooth operation even when handling fluids containing trace amounts of solid particles. The auxiliary impeller diameter is designed to be slightly larger than the main impeller; this precise dimensional matching transforms the auxiliary impeller into a more powerful gas compressor during the self-priming stage, generating a higher pressure ratio and thus propelling the gas to the outlet more rapidly, significantly improving self-priming speed and suction head limit. In pure water pumping, it acts as a second-stage booster unit, contributing a higher single-stage head due to its larger diameter, significantly increasing the total head of the two impellers connected in series and broadening the pump's application range. These complementary designs not only achieve rapid self-priming, efficient gas-liquid separation, high head output, and excellent flowability, but also bring implicit advantages such as lower operating vibration, lower noise, greater adaptability to complex operating conditions, and longer overall lifespan. Ultimately, this results in a compact, high-performance, and reliable leak-free magnetically driven pump. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention.

[0017] Figure 2 This is a cross-sectional view of the pump chamber of the present invention from the front.

[0018] Figure 3 This is a schematic diagram of the impeller assembly structure of the present invention.

[0019] Figure 4 This is a front view of the main impeller structure of the present invention.

[0020] In the diagram: 1. Pump chamber; 11. Converging cavity; 21. Main impeller; 22. Diffuser cavity; 23. Auxiliary impeller; 24. Guide block; 101. Inlet; 102. Outlet; 103. Exhaust port; 221. Diffuser channel; 241. Guide groove. Detailed Implementation

[0021] 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.

[0022] Please see Figures 1-4 A leak-free, magnetically driven self-priming vacuum pump includes a pump chamber 1, an inlet 101, an outlet 102, and an exhaust port 103. The pump chamber 1 is a cavity for housing an impeller assembly and is connected to the inlet 101, outlet 102, and exhaust port 103. The impeller assembly is driven magnetically by a motor. The impeller assembly in the pump chamber 1 includes a main impeller 21 and an auxiliary impeller 23. The main impeller 21 and the auxiliary impeller 23 are coaxially arranged and face opposite directions. The main impeller 21 faces the inlet 101 located at the front end of the pump chamber 1, and the auxiliary impeller 23 faces the outlet 102 located at the rear end of the pump chamber 1. An annular diffuser chamber 22 is provided on the outer side of the impeller 21. The diffuser chamber 22 has a diffuser channel 221 with a gradually increasing cross-section. A guide block 24 is provided between the main impeller 21 and the auxiliary impeller 23. The blades of the auxiliary impeller 23 are backward-curved blades. The backward-curved blades have long flow channels and gentle flow channel expansion. The process of guiding and accelerating the liquid in the flow channel is very smooth, and the eddy current and impact losses are minimized. If forward-curved blades are used, although the compressed gas may be slightly more powerful in the self-priming stage, it will continuously cause huge energy waste and extremely high operating costs during the normal water conveyance stage that lasts for thousands of hours.

[0023] During operation, the motor starts, driving the outer magnetic rotor to rotate. The outer magnetic rotor, through the isolation sleeve, drives the inner magnetic rotor and impeller within the sealed cavity to rotate synchronously. At this time, the exhaust port 103 is open because the float falls due to gravity, and the impeller rotation agitates the gas, generating a weak flow. Most of the gas in the pump chamber is directly discharged from the open exhaust port 103. The gas discharge reduces the pressure in the pump chamber, creating a micro-vacuum. Liquid in the inlet pipe begins to be drawn in slightly under atmospheric pressure. The impeller in pump chamber 1 is divided into a main impeller 21 and an auxiliary impeller 23, which are coaxially driven. Simultaneously, the main impeller 21 and the auxiliary impeller 23 face different directions. In the initial exhaust stage, the impeller rotation aims to establish a preliminary pressure gradient in a pure gas environment. However, conventional impellers... As the impeller rotates, its blades mechanically agitate the gas. Due to the gas's compressibility and low density, the main impeller 21 cannot effectively accelerate it, behaving more like an inefficient axial fan. It can generate a weak vacuum at its inlet, but its exhaust capacity is very limited. The auxiliary impeller 23 rotates synchronously. Because its blades face opposite to those of the main impeller 21, it counteracts and compresses the airflow coming from the direction of the main impeller 21. It can be considered a coarse compressor, pushing the gas at the rear of the pump chamber forward and preventing it from diffusing backward. The main impeller 21 "pulls" at the inlet, and the auxiliary impeller 23 "pushes" at the rear. Together, they quickly establish an initial pressure gradient from the inlet to the outlet within the pump chamber. Compared to traditional single-impeller pumps, this pull-and-push mode allows for faster self-priming. The process creates more favorable conditions for the intake of the first drop of liquid. In the gas-liquid mixing and separation cycle stage, when a small amount of liquid enters, the main impeller 21 becomes a high-speed agitator. It uses centrifugal force to violently shear and mix these liquids with the intake gas, forming a gas-liquid mixture with a density and inertia much greater than that of pure gas. The main impeller 21 efficiently transfers mechanical energy to the mixture, causing it to enter the diffuser chamber 22 at high speed. In the diffuser chamber 22, the flow velocity drops sharply, and gravity settling plays a dominant role. The liquid sinks, and the gas rises. The sinking liquid returns to the main impeller inlet through the return hole, providing liquid for the next mixing and maintaining the circulation. The gas that rises to the top of the pump chamber 1 and does not flow out of the exhaust port 103 flows to the auxiliary impeller 23. At this time, the auxiliary impeller 23 acts as the radial compressor. The main impeller 21, with its counter-rotating blades, further compresses the gas and applies a strong axial thrust towards the outlet. The main impeller 21 mixes the gas and liquid and performs initial gas separation, while the auxiliary impeller 23 pushes back the separated gas that hasn't been discharged, preventing it from stagnating in the pump chamber 1. It prevents gas from stagnating or forming vortices (gas dead zones) at the rear of the pump chamber 1, ensuring the gas is smoothly and quickly pushed towards the exhaust port 103. The auxiliary impeller provides additional gas delivery power, forming a dual-power system where the main impeller 21 draws in the gas-liquid mixture, and the auxiliary impeller pushes the gas. This significantly shortens the self-priming time and improves the ability to handle high gas content conditions. In the water delivery stage, the main impeller 21 acts as the first-stage centrifugal pump, initially pressurizing the liquid. Because liquids differ from gases...Since the fluid is incompressible, the auxiliary impeller 23 is a two-stage centrifugal pump. When the gas inside the pump is completely exhausted, and the last gas ball is compressed and pushed out by the auxiliary impeller, the pump chamber is instantly filled with a continuous stream of incompressible liquid. At this point, the force acting on the medium immediately changes from being primarily driven by the blades to being primarily driven by strong centrifugal force. The liquid flows from the main impeller through the intermediate guide block 24 into the auxiliary impeller 23, where it receives a second energy boost. The two impellers work in series, and the total head is the sum of the head of the main impeller and the head of the auxiliary impeller. This design is suitable for applications requiring higher heads. Because the main and auxiliary impellers are installed back-to-back, the axial forces they generate, pointing towards the inlet, are equal in magnitude and opposite in direction, perfectly canceling each other out. This greatly reduces the load on the thrust bearing and significantly improves the performance of the magnetic pump.

[0024] The guide block 24 is frustum-shaped, with a front diameter the same as the diffuser chamber 22 and a rear diameter the same as the auxiliary impeller 23. The guide block 24 has a conical spiral guide groove 241 on its side. The width of the guide block 24 is between 10% and 15% of the outer diameter of the main impeller 21. The guide block 24 guides the fluid, reducing the gap between the main impeller 21 and the auxiliary impeller 23, thus reducing the space required for the equipment. The frustum shape allows for a smooth fluid transition, avoiding turbulence and energy loss. The conical spiral guide groove may guide the fluid from radial to axial direction, reducing impact. The width limitation may be for a compact structure, reducing gaps and thus reducing the overall volume. The guide groove may enhance fluid control, prevent gas accumulation, and further improve gas-liquid separation efficiency. The compact design may reduce material costs and weight while maintaining structural strength.

[0025] The connection between the outlet 102 and the pump chamber 1 is located above the axis of the pump chamber 1, and the channel is set at a right angle upward. The cross-section of the tail end of the pump chamber 1 gradually decreases and contracts, and the inner wall edge of the pump chamber 1 is provided with rounded corners.

[0026] The upper half of the diffuser channel 221 in the diffuser chamber 22 has a wider cross-sectional width than the lower half. The wider upper part provides ample space for gas expansion and ascent, reducing flow resistance and allowing the gas to flow more smoothly to the volute, ready to enter the next stage. The relatively narrow lower part maintains a higher liquid flow rate while ensuring sufficient liquid storage, which helps guide the liquid to the return hole and prevents solid particles from settling. At the same time, this also maintains an effective "liquid seal" on the return hole.

[0027] The diameter ratio of the auxiliary impeller 23 to the main impeller 21 is 1.1. According to the basic law of centrifugal pumps, the head of the impeller is roughly proportional to the square of the outer diameter of the impeller. A larger auxiliary impeller means a stronger gas compression capacity. During the self-priming stage, it can generate a higher pressure ratio, more powerfully drive the gas, significantly shorten the self-priming time, and draw water from deeper wells. During normal operation, as a second-stage pump, it can contribute more head.

[0028] Working Principle: During the working phase, the motor starts, driving the outer magnetic rotor to rotate. The outer magnetic rotor, through the isolation sleeve, drives the inner magnetic rotor and impeller in the sealed cavity to rotate synchronously. At this time, the exhaust port 103 is open. Because the float falls due to gravity, the impeller rotates and agitates the gas, generating a weak flow. Most of the gas in the pump chamber is directly discharged from the open exhaust port 103. The discharge of gas causes the pressure in the pump chamber to decrease, forming a micro-vacuum. The liquid in the inlet pipe begins to be slightly drawn in under atmospheric pressure. The impeller in the pump chamber 1 is divided into a main impeller 21 and an auxiliary impeller 23, which are coaxially driven. At the same time, the main impeller 21 and the auxiliary impeller 23 face different directions. In the initial exhaust stage, the goal of the impeller rotation is to establish a preliminary pressure gradient in a pure gas environment, but... In a conventional impeller rotation, the blades mechanically agitate the gas. Due to the gas's compressibility and low density, the main impeller 21 cannot effectively accelerate it, behaving more like an inefficient axial fan. It can generate a weak vacuum at its inlet, but its exhaust capacity is very limited. The auxiliary impeller 23 rotates synchronously. Because its blades face opposite to the main impeller 21, it counteracts and compresses the airflow coming from the direction of the main impeller 21. It can be considered a coarse compressor, pushing the gas at the rear of the pump chamber forward and preventing it from diffusing backward. The main impeller 21 "pulls" at the inlet, and the auxiliary impeller 23 "pushes" at the rear. Together, they quickly establish an initial pressure gradient from the inlet to the outlet within the pump chamber. Compared to a traditional single impeller pump, this pull-and-push mode is faster. The self-priming process is initiated, creating more favorable conditions for the intake of the first drop of liquid. During the gas-liquid mixing and separation cycle, when a small amount of liquid enters, the main impeller 21 becomes a high-speed agitator. It uses centrifugal force to violently shear and mix these liquids with the intake gas, forming a gas-liquid mixture with a density and inertia much greater than that of pure gas. The main impeller 21 efficiently transfers mechanical energy to the mixture, causing it to enter the diffuser chamber 22 at high speed. In the diffuser chamber 22, the flow velocity drops sharply, and gravity settling plays a dominant role. The liquid sinks, and the gas rises. The sinking liquid returns to the main impeller inlet through the return hole, providing liquid for the next mixing and maintaining circulation. The gas that rises to the top of the pump chamber 1 and does not flow out of the exhaust port 103 flows to the auxiliary impeller 23. At this time, the auxiliary impeller 23 acts as a... The main impeller 21 acts as a radial compressor, with its counter-rotating blades further compressing the gas and applying a strong axial thrust towards the outlet. The main impeller 21 mixes the gas and liquid and performs initial gas separation, while the auxiliary impeller 23 pushes back the separated gas that hasn't been discharged, preventing it from stagnating in the pump chamber 1. It prevents gas from stagnating or forming vortices (gas dead zones) at the rear of the pump chamber 1, ensuring the gas is smoothly and quickly pushed towards the exhaust port 103. The auxiliary impeller provides additional gas delivery power, forming a dual-power system where the main impeller 21 draws in the gas-liquid mixture, and the auxiliary impeller pushes the gas. This significantly shortens the self-priming time and improves the ability to handle high gas content conditions. In the water delivery stage, the main impeller 21 acts as the first-stage centrifugal pump, initially pressurizing the liquid.Because liquids, unlike gases, are incompressible fluids, the auxiliary impeller 23 acts as a two-stage centrifugal pump. When the gas inside the pump is completely exhausted, and the last gas slick is compressed and pushed out by the auxiliary impeller, the pump chamber is instantly filled with a continuous stream of incompressible liquid. At this point, the force acting on the medium immediately changes from being primarily driven by the blades to being primarily driven by strong centrifugal force. The liquid flows from the main impeller through the intermediate guide block 24 into the auxiliary impeller 23, where it receives a second energy boost. The two impellers work in series, and the total head is the sum of the head of the main impeller and the head of the auxiliary impeller. This design is suitable for applications requiring higher heads. Since the main and auxiliary impellers are installed back-to-back, the axial forces they generate, pointing towards the inlet, are equal in magnitude and opposite in direction, perfectly canceling each other out. This greatly reduces the load on the thrust bearing and significantly improves the performance of the magnetic pump.

[0029] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A leak-free magnetically driven self-priming vacuum pump, comprising a pump chamber (1), an inlet (101), an outlet (102), and an exhaust port (103), wherein the pump chamber (1) is a cavity for housing an impeller assembly and is connected to the inlet (101), the outlet (102), and the exhaust port (103), and the impeller assembly is magnetically driven by a motor, characterized in that: The impeller assembly in the pump chamber (1) is provided with a main impeller (21) and an auxiliary impeller (23). The main impeller (21) and the auxiliary impeller (23) are coaxially arranged and face opposite directions. The main impeller (21) faces the inlet (101) at the front end of the pump chamber (1), and the auxiliary impeller (23) faces the outlet (102) at the rear end of the pump chamber (1). The main impeller (21) is provided with an annular diffuser chamber (22) on its outer side. The diffuser chamber (22) is provided with a diffuser channel (221) with a gradually increasing cross section. A guide block (24) is provided between the main impeller (21) and the auxiliary impeller (23). The blades of the auxiliary impeller (23) are backward-curved blades. The guide block (24) is frustum-shaped. The front diameter is the same as that of the diffuser chamber (22), and the rear diameter is the same as that of the auxiliary impeller (23). The guide block (24) is provided with a conical spiral guide groove (241) on its side.

2. The leak-free magnetically driven self-priming vacuum pump according to claim 1, characterized in that: The connection between the outlet (102) and the pump chamber (1) is located above the axis of the pump chamber (1), and the channel is set at a right angle upward.

3. The leak-free magnetically driven self-priming vacuum pump according to claim 2, characterized in that: The cross-section of the tail end of the pump chamber (1) gradually decreases and contracts.

4. The leak-free magnetically driven self-priming vacuum pump according to claim 2, characterized in that: The inner wall edge of the pump chamber (1) is rounded.

5. A leak-free magnetically driven self-priming vacuum pump according to any one of claims 1-4, characterized in that: The cross-sectional width of the upper half of the diffuser channel (221) in the diffuser cavity (22) is greater than that of the lower half of the diffuser channel (221).

6. A leak-free magnetically driven self-priming vacuum pump according to any one of claims 1-4, characterized in that: The diameter ratio of the secondary impeller (23) to the main impeller (21) is 1.1.

Images