Electromagnetic pump with reduced error propagation

Abstract

The application provides an electromagnetic pump with reduced error transmission, comprising a pump body, an electromagnetic coil arranged in the pump body, a plunger assembly driven by the electromagnetic coil to reciprocate, a water inlet one-way valve and a water outlet one-way valve; the water inlet one-way valve comprises a water inlet valve seat fixedly arranged on the pump body and a duckbill valve spool, the duckbill valve spool is fixedly installed on a plunger core of the plunger assembly and reciprocates synchronously with the plunger core, and cooperates with the water inlet valve seat to open or close a water inlet channel. The duckbill valve structure integrated in the plunger core is adopted, so that the transmission and accumulation of multiple error sources such as manufacturing error of a traditional tension spring, manufacturing error of a water inlet plug and the plunger, assembly direction deviation and stress distortion are completely eliminated, the flow control precision and stability are fundamentally improved, the output flow consistency of the electromagnetic pump is greatly improved, and the flow stability and control precision are significantly improved.

Description

Technical Field

[0001] This utility model relates to the field of pumps, and in particular to a reciprocating plunger electromagnetic pump. Background Technology

[0002] Electromagnetic pumps, especially reciprocating plunger electromagnetic pumps, are widely used in applications requiring precise control of minute flow rates, such as coffee machines, water dispensers, and medical equipment, due to their compact structure, low cost, and ease of control. Their working principle involves energizing an electromagnetic coil to drive a plunger in reciprocating motion, which, in conjunction with inlet and outlet check valves, pumps fluid from the low-pressure side to the high-pressure side.

[0003] In existing technology, electromagnetic pumps use a tension spring as the return element for the plunger. Specifically, the plunger core is typically designed as a hollow cylindrical structure. One end of a tension spring passes through the hollow part of the plunger and is fixed to the tail of the plunger by a slightly larger structure or clip; the other end of the tension spring is connected to a separate inlet plug, such as... Figure 1 As shown. When the plunger returns to its original position, the inlet plug forms a sealing surface with the valve seat on the pump body. When the plunger is attracted by electromagnetic force, the tension spring is stretched, and the inlet plug leaves the valve seat to open the flow channel.

[0004] However, the traditional tension spring-inlet plug type return seal structure has many inherent defects, making it difficult to improve the overall performance of the pump, especially the accuracy and stability of flow control. These defects are mainly reflected in the following aspects: ① Multiple sources of error with significant cumulative effects: The performance of this structure depends on the precise fit of multiple discrete parts, including the manufacturing tolerances of the spring's stiffness, length, and diameter, the machining accuracy of the inlet plug, and the dimensional accuracy of the plunger's hollow channel. The dimensional errors of these parts directly transmit and accumulate to the final sealing effect and return force, resulting in performance differences between different pump bodies or even the same pump body at different times.

[0005] ② The assembly process is complex and introduces human error: The tension spring must be inserted into the hollow hole of the slender plunger and connected to the inlet plug, a process that usually requires manual operation. During assembly, the tension spring is easily subjected to unexpected stretching and twisting, changing its initial state and introducing uncontrollable assembly stress and directional deviations. This lack of repeatability due to human intervention directly leads to a decrease in product consistency.

[0006] ③ Complex structure, contradiction between cost and reliability: As an independent moving part, the fit error between the inlet plug and the plunger core necessitates multiple precision machining processes for the plunger core, resulting in high processing difficulty and cost. Simultaneously, the assembly accuracy requirements are extremely high, making it highly susceptible to issues such as misalignment or burrs affecting the reliability and stability of the seal, leading to unstable flow output.

[0007] In summary, existing electromagnetic pumps suffer from inherent design flaws in their return and sealing structures, resulting in long error chains, difficult assembly, low consistency, and unstable flow control. This has become a critical technical bottleneck in high-precision fluid metering applications, such as the precise control of pre-infusion flow and pressure in high-end coffee machines. Therefore, there is an urgent need in this field for a novel electromagnetic pump structure that can fundamentally simplify design, eliminate the transmission and accumulation of multiple error sources, and thereby improve flow control accuracy, stability, and product consistency. Summary of the Invention

[0008] To address the shortcomings of the existing technology, this utility model provides an electromagnetic pump that reduces error transmission, eliminating multiple error sources present in the traditional spring-inlet plug return structure, thereby significantly improving the stability and accuracy of flow control.

[0009] The specific technical solution is as follows: An electromagnetic pump for reducing error propagation includes a pump body, an electromagnetic coil disposed within the pump body, a plunger assembly driven by the electromagnetic coil to reciprocate, an inlet check valve, and an outlet check valve. The inlet check valve includes an inlet valve seat fixedly mounted on the pump body and a duckbill valve core. The duckbill valve core is fixedly mounted on the plunger core of the plunger assembly and reciprocates synchronously with the plunger core, cooperating with the inlet valve seat to open or close the inlet channel. The duckbill valve core and plunger core cooperation structure replaces the traditional tension spring-inlet plug structure, utilizing the elastic deformation of the duckbill valve itself to achieve valve opening and sealing. During the plunger's return stroke, a negative pressure is formed in the pump chamber, and the water pressure causes the duckbill valve lip to open; during the plunger's advance, the water pressure in the pump chamber and the duckbill valve's own rebound force cause its lip to close. This fundamentally eliminates the two independent error sources: the tension spring and the inlet plug.

[0010] Furthermore, the outer wall of the aforementioned plunger core is provided with a mounting groove, and the duckbill valve core is tightly fitted onto the mounting groove through its own elastic deformation. This is a simple and reliable mechanical connection method. The mounting groove provides a clear positioning and installation base for the duckbill valve, and the elasticity of the duckbill valve material allows it to be firmly clamped in the groove, ensuring that there is no relative displacement between the two during high-speed reciprocating motion, making the assembly process extremely simple.

[0011] Furthermore, the aforementioned mounting groove is an annular mounting groove. The annular groove design ensures that the circumferential force on the duckbill valve core is uniform, avoiding potential issues such as uneven wear or poor sealing caused by asymmetrical fixing, thus guaranteeing operational stability and reliability.

[0012] Furthermore, the cross-sectional shape of the aforementioned mounting groove is one of rectangular, trapezoidal, V-shaped, or semi-circular. The mounting groove can be further optimized according to different spatial layouts and mechanical requirements. Different groove shapes offer diverse design options. Trapezoidal and V-shaped grooves provide guidance and facilitate assembly; rectangular and semi-circular grooves offer a larger contact area and support stability.

[0013] Furthermore, the ratio of the depth (H) of the mounting groove to the wall thickness (T) of the duckbill valve core satisfies: 0.2 ≤ H / T ≤ 0.8. This ratio is an optimized critical dimension, balancing the relationship between fixation reliability and valve core functionality. If H / T is too small (groove too shallow), the duckbill valve may not be securely fixed and is prone to detachment; if H / T is too large (groove too deep), it will excessively compress the duckbill valve, weakening its effective elastic deformation capacity of the lip and affecting the opening and sealing performance of the valve port.

[0014] Furthermore, the pump body is equipped with a guide sleeve made of a self-lubricating material, which slides within the plunger assembly. The guide sleeve constrains the plunger assembly, ensuring its movement strictly along the axial direction, greatly reducing runout and friction during movement. Using a self-lubricating material (such as POM) allows for low-friction, long-life operation without external lubrication, further reducing errors caused by deviations in movement direction and unstable frictional resistance.

[0015] Furthermore, the aforementioned plunger core is equipped with a hollow flow channel for fluid passage, which can be a uniform or non-uniform flow channel. In the traditional tension spring-inlet plug design, the original slender tension spring had to be installed at one end at the tail of the plunger core and pass through the hollow part, relying on the hollow part of the plunger core for guidance during reciprocating deformation. Therefore, the original hollow part had to be cylindrical, and a slot had to be left at the tail for fixing the tension spring. With the current new structure, the shape restrictions on the hollow part are eliminated; only a hollow structure is required to form a water flow channel, greatly liberating design freedom. The "uniform flow channel" is easy to manufacture and meets basic flow requirements; the "non-uniform flow channel" allows for optimized design based on fluid dynamics performance (such as changing the cross-sectional area to accelerate the fluid or changing the shape to reduce eddies), laying the foundation for subsequent performance improvements, while eliminating the need for precision machining to accommodate the tension spring.

[0016] Furthermore, the aforementioned plunger core is composed of at least two coaxial hollow cylindrical sections with different outer diameters.

[0017] Furthermore, the inlet end of the aforementioned plunger core has a streamlined spindle or conical shape. This represents a comprehensive optimization of the plunger core's external morphology after liberating design freedom, offering dual benefits in fluid dynamics and electromagnetics. The streamlined shape (spindle or conical) effectively guides water flow smoothly around the plunger end, significantly reducing fluid resistance and eddy current generation during reciprocating motion, thus helping to reduce drive energy consumption, operating noise, and vibration. As part of the plunger core's drive end, the shape and volume of the streamlined spindle or conical structure directly alter the magnetic reluctance and flux distribution in the electromagnetic field at that location. By optimizing this shape, the magnetic field strength can be adjusted, allowing the plunger core to obtain a better or more consistent electromagnetic driving force at different positions in its stroke, thereby further improving drive efficiency and control precision.

[0018] Furthermore, the cross-sectional area of ​​the hollow flow channel gradually decreases from its inlet to its outlet, forming a tapered flow channel. This is a fluid dynamics optimization of the internal flow channel of the plunger core after freeing up design freedom. The principle utilized is the application of the Venturi effect; the gradual decrease in the cross-sectional area of ​​the flow channel increases the fluid velocity and reduces the pressure. This creates an additional low-pressure zone inside the flow channel during the plunger's return stroke, which helps to draw in water more quickly and efficiently, thereby improving the pump's suction performance and high-frequency response characteristics.

[0019] Compared with the prior art, the present technical solution has the following beneficial technical effects: (1) By adopting a duckbill valve structure integrated into the plunger core, the transmission and accumulation of multiple error sources such as manufacturing error of traditional tension spring, manufacturing error of water inlet plug and plunger, assembly direction deviation and stress distortion are completely eliminated, fundamentally improving the flow control accuracy and stability, greatly improving the consistency of the output flow of electromagnetic pump, and significantly enhancing flow stability and control accuracy.

[0020] (2) The structure has been simplified and the original assembly process has been completely changed. Not only are the precision requirements for the tension spring, plunger core and water inlet plug eliminated, but the original manual assembly process (the thin end of the tension spring passes through the plunger core hole, is stretched and deformed and connected to the water inlet plug and then released) can be quickly and reliably fixed through a simple mounting groove, realizing automated assembly, which greatly improves production efficiency and product consistency, while reducing quality fluctuations caused by complex manual assembly and reducing manufacturing and assembly costs.

[0021] (3) It liberates design freedom and achieves comprehensive performance optimization. It eliminates the limitation of having to design a precision through hole to accommodate the tension spring. The hollow flow channel and external shape of the plunger core can be optimally designed according to functional requirements. From a fluid dynamics perspective, the streamlined drive end (spindle-shaped / conical) effectively reduces fluid resistance and vibration noise; the tapered internal flow channel utilizes the Venturi effect to improve suction performance and high-frequency response. From an electromagnetic perspective, by changing the shape and volume of the plunger core drive end, its magnetic reluctance and magnetic flux distribution can be actively adjusted, thereby obtaining a more efficient and consistent electromagnetic driving force during the stroke, further improving comprehensive performance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the principle of an existing plunger-type electromagnetic pump; Figure 2 This is a schematic cross-sectional view of the electromagnetic pump in Example 1; Figure 3 This is a schematic diagram showing the fit between the plunger core and the duckbill valve core in Example 1; Figure 4 This is a schematic diagram showing the fit between the plunger core and the duckbill valve core in Example 2; Figure 5 This is a cross-sectional schematic diagram of the hollow channel in Example 3.

[0023] Labeling Explanation: 11, plunger core; 12, tension spring; 21, inlet plug; 22, inlet valve seat; 23, mounting groove; 24, duckbill valve core; 31, outlet plug; 32, outlet plug spring; 4, sealing limit component; 111, cylindrical outlet end; 112, cylindrical suction end; 113, streamlined spindle-shaped suction end; 114, conical suction end. Detailed Implementation

[0024] To better understand the technical solution and beneficial effects of the present invention, the present invention will be further described below with reference to specific embodiments. It should be understood that the embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0025] The internal components of miniature electromagnetic pumps are typically millimeter-sized. At such a small scale, the machining of precision hollow channels, the assembly of slender tension springs, and the precision required for the fit between multiple tiny components are extremely high, resulting in high cost and low reliability. Any minute machining error or assembly stress will be amplified within this millimeter-scale space, leading to a sharp decline in performance.

[0026] The following technical solution fundamentally overturns the traditional process. It eliminates the precision assembly steps such as spring threading and hooking, which are almost impossible to automate and rely entirely on skilled workers for manual work. Instead, it employs a simple, reliable, and easily automated assembly method where the duckbill valve and mounting slot are simply snapped together. This not only improves production efficiency but also completely eliminates the uncertainty and quality fluctuations caused by manual operation. Simultaneously, liberating the plunger core design freedom is another major technological breakthrough. This invention no longer requires the plunger core to be a high-cost, precision deep-hole guide sleeve, allowing it to adopt more easily machinable non-uniform flow channels and external shapes. This means that the plunger core can be manufactured using standard profiles, modular designs, or more efficient machining methods, significantly reducing the reliance on the extreme machining precision of individual components while ensuring functionality and even improving performance. This achieves the optimal balance of strength, precision, and manufacturing cost at the millimeter scale.

[0027] Example 1 An electromagnetic pump that reduces error propagation, such as Figure 2 As shown, the pump mainly includes a pump body, an electromagnetic coil, a plunger assembly, an inlet check valve, and an outlet check valve. The electromagnetic coil is fixedly installed in the coil cavity of the pump body by interference fit or adhesive bonding. The plunger assembly passes through the pump body and can reciprocate within it. The plunger assembly includes a plunger core 11, preferably made of soft magnetic material, industrial pure iron. The stroke of the plunger core 11 is limited by the sealing limiter 4. A guide sleeve made of self-lubricating polyoxymethylene (POM) is also press-fitted into the pump body, slidingly engaging with the plunger core 11 to ensure that the plunger assembly can only reciprocate along the axial direction, without circumferential rotation or radial wobble. The inlet check valve consists of an inlet valve seat 22 and a duckbill valve core 24. The outlet check valve is located at the outlet end of the pump body and includes an outlet plug 31 and an outlet plug spring 32.

[0028] The duckbill valve core 24 is made of food-grade silicone with a Shore hardness of HA50. An annular rectangular cross-section mounting groove 23 is machined on the outer wall of the plunger core 11. The duckbill valve core 24 is firmly fitted onto the mounting groove 23 through its own elastic deformation. The ratio of the depth H of the mounting groove 23 to the wall thickness T of the duckbill valve core 24 is H / T = 0.5.

[0029] The plunger core 11 consists of a cylindrical outlet end 111 and a cylindrical suction end 112, forming a uniform circular hollow flow channel for fluid passage. The cylindrical suction end 111 and the cylindrical outlet end 112 have different outer diameters. Thus, the duckbill valve core 24 and the plunger core 11 are integrated into a single unit and move synchronously with each other, such as... Figure 3 As shown.

[0030] Example 2 An electromagnetic pump for reducing error propagation mainly includes a pump body, an electromagnetic coil, a plunger assembly, an inlet check valve, and an outlet check valve. The electromagnetic coil is fixedly installed in the coil cavity of the pump body via an interference fit or adhesive bonding. The plunger assembly passes through the pump body and can reciprocate within it. The plunger assembly includes a plunger core 11, preferably made of soft magnetic industrial pure iron. The stroke of the plunger core 11 is limited by a sealing limiter 4. A guide sleeve made of self-lubricating polyoxymethylene (POM) is also press-fitted into the pump body, slidingly engaging with the plunger core 11 to ensure that the plunger assembly can only reciprocate along the axial direction, without circumferential rotation or radial wobble. The inlet check valve consists of an inlet valve seat 22 and a duckbill valve core 24. The outlet check valve is located at the outlet end of the pump body and includes an outlet plug 31 and an outlet plug spring 32.

[0031] The duckbill valve core 24 is made of rubber with a Shore hardness of HA80. An annular V-shaped mounting groove 23 is machined on the outer wall of the plunger core 11. The duckbill valve core 24, through its own elastic deformation, is firmly fitted onto the mounting groove 23. The ratio of the depth H of the mounting groove 23 to the wall thickness T of the duckbill valve core 24 is H / T = 0.2. Thus, the duckbill valve core 24 and the plunger core 11 are integrated into a single component and move synchronously with each other.

[0032] The plunger core 11 consists of a cylindrical outlet end 111 and a streamlined spindle-shaped suction end 113, forming a uniform circular hollow flow channel inside for fluid passage, such as... Figure 4 As shown, the streamlined spindle-shaped end profile of the plunger core 11 can significantly reduce fluid resistance during plunger movement, reduce vibration and noise, and at the same time change the magnetic field distribution at the end of the plunger core, optimize its electromagnetic force characteristics during the stroke, and make the drive smoother.

[0033] Example 3 An electromagnetic pump for reducing error propagation mainly includes a pump body, an electromagnetic coil, a plunger assembly, an inlet check valve, and an outlet check valve. The electromagnetic coil is fixedly installed in the coil cavity of the pump body via an interference fit or adhesive bonding. The plunger assembly passes through the pump body and can reciprocate within it. The plunger assembly includes a plunger core 11, preferably made of soft magnetic industrial pure iron. The stroke of the plunger core 11 is limited by a sealing limiter 4. A guide sleeve made of self-lubricating polyoxymethylene (POM) is also press-fitted into the pump body, slidingly engaging with the plunger core 11 to ensure that the plunger assembly can only reciprocate along the axial direction, without circumferential rotation or radial wobble. The inlet check valve consists of an inlet valve seat 22 and a duckbill valve core 24. The outlet check valve is located at the outlet end of the pump body and includes an outlet plug 31 and an outlet plug spring 32.

[0034] The duckbill valve core 24 is made of rubber with a Shore hardness of HA30. An annular trapezoidal mounting groove 23 is machined on the outer wall of the plunger core 11. The duckbill valve core 24, through its own elastic deformation, is firmly fitted onto the mounting groove 23. The ratio of the depth H of the mounting groove 23 to the wall thickness T of the duckbill valve core 24 is H / T = 0.8. Thus, the duckbill valve core 24 and the plunger core 11 are integrated into a single component and move synchronously with each other.

[0035] The plunger core 11 consists of a cylindrical outlet end 111 and a conical suction end 114, forming a hollow flow channel for fluid passage. The hollow flow channel is constructed as a tapered channel, meaning its cross-sectional area gradually decreases from the suction end to the outlet end, such as... Figure 5 As shown in the figure. This structure utilizes the Venturi effect, where the water flow velocity in the flow channel increases and the pressure decreases during the plunger's return stroke, creating an additional low-pressure zone. This significantly improves the pump's suction performance, making its response more rapid under high-frequency operation.

[0036] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For example, the cross-sectional shape of the mounting groove 23 can be trapezoidal, V-shaped, etc.; the duckbill valve core 24 can also be made of oil-resistant rubber; the plunger core 11 can also be designed as a three-section type or other non-uniform shape as needed. Any modifications and equivalent substitutions made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electromagnetic pump that reduces error propagation, characterized in that, The system includes a pump body, an electromagnetic coil disposed within the pump body, a plunger assembly driven by the electromagnetic coil to reciprocate, an inlet check valve, and an outlet check valve. The inlet check valve includes an inlet valve seat fixedly disposed on the pump body and a duckbill valve core. The duckbill valve core is fixedly installed on the plunger core of the plunger assembly and reciprocates synchronously with the plunger core, cooperating with the inlet valve seat to open or close the inlet channel.

2. The electromagnetic pump according to claim 1, characterized in that, The outer wall of the plunger core is provided with an installation groove, and the duckbill valve core is tightly fitted onto the installation groove by its own elastic deformation.

3. The electromagnetic pump according to claim 2, characterized in that, The mounting groove is an annular mounting groove.

4. The electromagnetic pump according to claim 2, characterized in that, The cross-sectional shape of the mounting groove is one of rectangle, trapezoid, V-shape or semi-circle.

5. The electromagnetic pump according to claim 2, characterized in that, The ratio of the depth (H) of the mounting groove to the wall thickness (T) of the duckbill valve core satisfies: 0.2 ≤ H / T ≤ 0.

8.

6. The electromagnetic pump according to claim 1, characterized in that, The pump body is provided with a guide sleeve, which is made of a self-lubricating material, and the plunger assembly slides in conjunction with the guide sleeve.

7. The electromagnetic pump according to claim 1, characterized in that, The plunger core is provided with a hollow flow channel for fluid to pass through, and the hollow flow channel can be a uniform flow channel or a non-uniform flow channel.

8. The electromagnetic pump according to claim 7, characterized in that, The plunger core is composed of at least two coaxial hollow cylindrical sections with different outer diameters.

9. The electromagnetic pump according to claim 7, characterized in that, The water-absorbing end of the plunger core has a streamlined spindle shape or a cone shape.

10. The electromagnetic pump according to claim 7, characterized in that, The cross-sectional area of ​​the hollow channel gradually decreases from its water intake end to its water outlet end, forming a tapered channel.

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