A liquid heater

Abstract

The utility model discloses a liquid heater, including inner bag, water pump and water outlet nozzle, and the inner bag is passed through water pump and water outlet nozzle intercommunication, and the water pump includes metal front shell and drive part, and metal front shell and drive part cooperation enclose metal cavity, and the drive part is provided with the drive motor, and the metal cavity is provided with the impeller, and the motor shaft of drive motor is provided with the drive magnet, and the impeller is provided with the driven magnet, and the metal front shell is provided with the water inlet that communicates metal cavity, and the liquid heater still includes the metal spacing piece that sets up with metal front shell, and the metal spacing piece is set up to limit the axial movement of impeller in the working process with the water inlet. The metal front shell is metal material, and its structural strength is guaranteed, and the high temperature resistance is better, can guarantee the clean of water quality, is favorable to the user drinking. The metal spacing piece can form the stop limit to the axial movement of impeller when working, and the probability of the scratch abrasion of impeller and metal front shell inner wall is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of household appliance technology, and specifically relates to a liquid heater. Background Technology

[0002] Liquid heaters, such as tea makers, health pots, electric kettles, coffee extractors, milk makers, and electric water bottles, are typically used in liquid heaters. A water pump, as a crucial component of a liquid heater, usually consists of a housing and a drive motor and impeller housed within it. In traditional water pumps, the drive motor directly drives the impeller via a transmission shaft, causing it to rotate. However, during operation, the impeller needs to be in direct contact with the liquid, while the drive motor needs to avoid contact to prevent malfunctions and extend the pump's lifespan. Therefore, sealing between the two becomes challenging, requiring both reliable transmission and a waterproof seal for the drive motor.

[0003] Therefore, in the prior art, for example, Chinese patent CN207004844U discloses a water pump, including a motor, a front housing, a rear housing, and a shaped water impeller. The shaped water impeller is disposed inside the rear housing. A middle partition and a sealing ring are provided between the front and rear housings to separate their interiors. A fixed shaft is fixedly connected to the center of the middle partition facing the rear housing via injection molding. A driven magnetic ring is fixedly connected to the shaped water impeller via injection molding. The driven magnetic ring is movably fitted outside the fixed shaft and can rotate around the center of the fixed shaft. The motor has an output shaft, and an active magnetic ring is fixedly connected to the front end of the output shaft. The active and driven magnetic rings are located on opposite sides of the middle partition, and are driven by magnetic attraction. In the above solution, by arranging the motor and the shaped water impeller in two cavities and isolating and sealing them with a middle partition and a sealing ring, non-contact magnetic attraction transmission is achieved using the active and driven magnetic rings, which helps to extend the service life of the water pump.

[0004] However, in the case of magnetic coupling drive, the impeller will slide axially under the action of centrifugal force during high-speed rotation, causing the impeller to hit the pump casing and causing the pump to malfunction.

[0005] Chinese patent CN201599211U discloses a water pump for a water dispenser / electric thermos, which has a positioning post for fixing the shaped water blades inside the cavity of the front shell. A baffle is provided on the side of the positioning post to strengthen the structure of the positioning post and reduce bubbles. This improves the fixing effect on the shaped water blades (impeller). In the above solution, the baffle is only located on one side of the fixing post, failing to provide a good separation effect on the water inlet, and the effect of cutting and breaking bubbles is also poor.

[0006] Furthermore, the housing of water pumps is typically made of plastic. For example, in the first patented solution mentioned above, the front housing, rear housing, and middle partition are all injection-molded parts. Plastic has poor high-temperature resistance and will age or develop odors with frequent contact with hot water. Many plastics also contain plasticizers (such as phthalates) to increase flexibility. When plastic parts are in contact with water for extended periods, these chemicals gradually dissolve into the water, especially when in contact with hot water or oil, where the migration rate accelerates. Long-term consumption may pose potential health risks. In addition, plastic parts have internal stress during molding, which can induce cracking with prolonged water contact, causing components to suddenly break under stress far below their strength limits, severely impacting the pump's lifespan and user experience. Simply replacing the housing material with another increases the difficulty of setting up structures such as the mounting posts, making the pump's manufacturing process more challenging. Utility Model Content

[0007] This utility model provides a liquid heater that addresses the problem of axial movement and collision wear between the impeller and the pump housing when using magnetic drive impeller. It also solves the problems of the pump housing being made of plastic, which has low structural strength, affects water quality after prolonged contact with water, and makes the internal components of the pump difficult to process.

[0008] The technical solution adopted in this utility model is as follows:

[0009] A liquid heater includes an inner tank, a water pump, and a water outlet. The inner tank is connected to the water outlet via the water pump. The water pump includes a metal front shell and a drive unit, which cooperate to form a metal cavity. A drive motor is installed inside the drive unit, and an impeller is installed inside the metal cavity. A drive magnet is installed on the motor shaft of the drive motor, and a driven magnet is installed on the impeller. The metal front shell has a water inlet communicating with the metal cavity. The liquid heater also includes a metal limiting member that is separate from the metal front shell and spans the water inlet to restrict the impeller from moving axially during operation.

[0010] In this invention, the drive motor drives the driven magnet to rotate the impeller through the active magnet, thus achieving magnetic drive. Compared with direct drive, magnetic drive can achieve non-contact drive, allowing the drive motor and impeller to be arranged in two separate cavities. The cavity containing the impeller (metal cavity) allows liquids such as water to enter, while the cavity containing the drive motor is sealed, preventing liquids from contacting the drive motor. This reduces the possibility of the drive motor malfunctioning due to water and improves its service life.

[0011] Furthermore, in this invention, the metal front shell and the drive unit cooperate to form a metal cavity, with the impeller located within the metal cavity. When the water pump is working, water enters the metal cavity and comes into direct contact with the metal front shell. Since the metal front shell is made of metal, its structural strength is guaranteed compared to plastic, reducing the risk of breakage and extending the overall service life of the water pump. Moreover, metal has better high-temperature resistance and is more stable; even when in prolonged contact with water, especially hot water, no chemicals will dissolve into the water, thus ensuring water purity and benefiting drinking water. In this invention, based on the materials of the metal front shell and the metal limiting component, they are designed as separate structures. They can be manufactured separately, and the metal limiting component is then fixed to the metal front shell through subsequent assembly. Because metal is more difficult and costly to process than plastic, the separate design reduces the structural complexity of individual components, thereby reducing the processing difficulty of each component and improving production efficiency and yield.

[0012] A metal limiting component spans the inlet, completely dividing it into at least two flow channels. As water flows through the inlet, the metal limiting component cuts, squeezes, and collides with water bubbles, aiding in bubble bursting and improving the bubble-breaking effect. Furthermore, the metal limiting component stops and limits the axial movement of the impeller during operation. Specifically, a certain gap is reserved between the metal limiting component and the impeller. When the impeller rotates axially, if the movement exceeds this gap, it will contact the metal limiting component and stop. Under the restraining effect of the metal limiting component, the impeller cannot undergo significant axial movement, thus improving the impeller's positional stability during operation and reducing the probability of scratching and wear between the impeller and the inner wall of the metal front casing. This reduces wear on both the metal front casing and the impeller, extending their service life, and also avoids noise generated when they collide, reducing the overall noise level of the machine and improving the user experience.

[0013] The metal cavity has a metal cavity wall on the side opposite to the drive unit, and there is an assembly gap between the impeller and the metal limiting member, which is smaller than the distance between the impeller and the metal cavity wall.

[0014] Metal limiting components restrict the impeller by forming a stop through contact. However, if the impeller contacts the metal limiting component when not in operation, while this provides better axial restraint, the constant contact and friction during impeller rotation generates noise and creates resistance, increasing the load and reducing efficiency. This design incorporates an assembly gap between the impeller and the metal limiting component. After assembly, they do not contact each other, allowing for a certain margin of axial movement. Theoretically, without deformation of the metal limiting component, the assembly gap represents the range of axial movement the impeller can achieve. When the axial displacement is less than the assembly gap, the impeller will not stop, allowing for free and smooth rotation without frictional resistance from the metal limiting component. When the axial movement of the impeller increases to the point of contact with the metal limiting component, the two form a stop. At this time, the metal limiting component restricts the axial movement of the impeller, preventing it from undergoing large-amplitude axial movement. Simultaneously, the assembly clearance is smaller than the distance between the impeller and the metal cavity wall. This ensures that even when the impeller contacts the metal limiting component to form a stop, a gap still exists between the impeller and the metal cavity wall. This means the maximum axial displacement of the impeller is less than its distance from the metal cavity wall, thus preventing scratching and collision between the impeller and the metal cavity wall, reducing the possibility of such collisions.

[0015] The metal limiting component includes a limiting part and a fixing part located at the end of the limiting part. The limiting part is used to limit the impeller, and the fixing part is fixed to the metal front shell. There is an included angle α between the fixing part and the limiting part, wherein 0°≤α≤180°.

[0016] Since the metal limiting component and the metal front shell are separate structures, they need to be fixedly connected later. However, the inner wall of the metal front shell is often a non-planar structure, such as an arc or inclined surface, making it difficult to fix to the metal limiting component. The non-planar structure also results in a small contact area at the fixing point, making it difficult to guarantee the stability of the metal limiting component. In this solution, the metal limiting component includes a limiting part and a fixing part located at the end of the limiting part, arranged at an angle, making the metal limiting component a bent structure. By setting the angle, the extension directions of the fixing part and the limiting part are set to address both the ease of fixing and the reliability of limiting. For example, the limiting part can be perpendicular to the axis of the inlet to ensure reliable contact with the impeller and form a limiting effect, making the contact more stable and reducing the possibility of slippage. Similarly, the fixing part can be designed at an angle that makes it easier to connect to the metal front shell, thereby reducing the difficulty of fixing, increasing the contact area at the connection point, and improving the fixing effect.

[0017] The metal limiting member is a strip-shaped structure, and there is only one metal limiting member. Both ends of the metal limiting member are fixed to the metal front shell. At least a portion of the middle region of the metal limiting member is coaxially arranged with the impeller to limit the impeller. Alternatively, the metal limiting member includes a plurality of fixing parts that are circumferentially spaced along the inlet and fixed to the metal front shell, and limiting parts that extend radially inward from the fixing parts along the inlet and intersect each other. The intersection of the limiting parts forms a stop area, and the stop area is coaxially arranged with the impeller to limit the impeller.

[0018] The metal limiting component is used to stop and limit the impeller. Therefore, it must ensure both the limiting effect on the impeller and the water intake efficiency of the inlet. Simultaneously, the metal limiting component is also subjected to the impact force from the water flow entering through the inlet and the extrusion force from the impeller. Therefore, the connection strength and stability between the metal limiting component and the inner wall of the metal cavity are also subject to high requirements. In this design, the metal limiting component is a single strip structure. Both ends are fixedly connected to the inner wall of the metal cavity, and the middle area between the two ends limits the impeller. The fixed ends enhance the fixing strength of the metal limiting component, allowing it to stably stop the impeller. At the same time, the strip-shaped metal limiting component divides the inlet into two parts, avoiding excessive obstruction and allowing water to flow through both sides of the metal limiting component, ensuring water intake efficiency. In another design, the metal limiting component comprises multiple strip-shaped structures extending inward from different positions around the inlet. These limiting sections intersect at the center to form a stop zone. Compared to a single metal limiting component, the stop zone has superior structural strength, capable of withstanding greater thrust from the impeller without easily deforming, thus ensuring reliable impeller limiting. Simultaneously, the fixing parts are secured to multiple areas of the metal front shell, improving the fixing strength and stability between the metal limiting component and the metal front shell, reducing the possibility of detachment. A water passage gap is formed between adjacent fixing parts, allowing water to flow through and also acting as a guide, making the water flow more orderly and reducing the possibility of turbulence.

[0019] The metal limiting component has a mesh structure and is provided with water-passing mesh holes. The impeller has a protruding mating part on the side facing the water inlet, and the opening area of ​​the water-passing mesh holes is smaller than the cross-sectional area of ​​the mating part.

[0020] In this design, the metal front shell has a mesh structure. The opening area of ​​the water-passing mesh is smaller than the cross-sectional area of ​​the impeller's mating part. This allows the metal limiting component to also stop and limit the impeller while allowing water to pass through. Water from the inlet can enter the metal cavity through the water-passing mesh, which filters out large particles of impurities, preventing them from being drawn into the impeller and hindering its rotation. Simultaneously, the mating part cannot pass through the water-passing mesh, thus forming a stop with the metal limiting component and restricting the impeller's axial movement. Furthermore, the impeller's end face does not come into contact with the metal limiting component due to the protruding mating part, preventing complete blockage of the water-passing mesh. Even when the mating part comes into contact with the metal limiting component, only a portion of the water-passing mesh may be blocked, while the majority of the mesh remains open for water flow.

[0021] The metal limiting member includes a limiting part and a fixing part located at the end of the limiting part. The limiting part is recessed in the direction away from the impeller to form a mating surface on the side of the limiting part facing the impeller.

[0022] To ensure reliable impeller positioning by the metal limiting component, precise control of the assembly gap between them is crucial. However, due to machining and assembly errors, this gap is often difficult to control. Furthermore, the metal limiting component is a thin-walled structure; when the impeller contacts it, the significant pushing force from the impeller can cause deformation, increasing the gap and affecting its positioning effectiveness. This solution addresses this by recessing the limiting portion away from the impeller to form a mating surface. This surface provides clearance for the impeller, allowing for more accurate design and control of the gap. Additionally, when the impeller contacts the metal limiting component, the contact force is dispersed across the curved surface, mitigating localized stress and reducing the likelihood of deformation. Moreover, curved surfaces offer higher structural strength than planar structures, further reducing the probability of deformation and ensuring structural and positional reliability.

[0023] The metal front shell has a surrounding wall extending outward from the metal cavity along the axial direction of the impeller on the outer periphery of the water inlet. The surrounding wall forms a water inlet channel. The water inlet channel includes a first extension section and a second extension section along the axial direction of the impeller. The inner diameter of the first extension section is larger than the inner diameter of the second extension section to form a stepped surface between the two. The metal limiting member includes a limiting part and a fixing part located at the end of the limiting part. The extension direction of the fixing part is parallel to the water inlet channel, and the end face of the fixing part abuts against the stepped surface. The outer peripheral surface of the fixing part abuts against the inner wall of the first extension section.

[0024] If the metal limiting component is placed inside the metal cavity, it will occupy part of the internal space, restricting the impeller's installation space and increasing the risk of interference between the impeller and the inner wall of the metal cavity or the metal limiting component during rotation. In this solution, a water inlet channel is formed outside the metal front shell, and the metal limiting component is placed inside the water inlet channel. This allows the metal limiting component to perform its limiting function without occupying internal space within the metal cavity, making impeller installation easier and providing sufficient space for smooth impeller rotation. However, the inner wall of the water inlet channel is a circular surface, making it difficult to connect with the metal limiting component. This solution designs the extension direction of the fixing part to be parallel to the water inlet channel, allowing the metal limiting member to insert the fixing part into the first extension section. This causes the end face of the fixing part to abut against the stepped surface, and the outer peripheral surface to abut against the inner wall of the first extension section. This not only reduces the installation difficulty of the metal limiting member, but also allows the fixing part to be fixed to the water inlet channel through two vertical surfaces, greatly increasing the contact area and improving the fixing stability. At the same time, the inner wall of the first extension section also forms an inward clamping force on the fixing part, making the metal limiting member more firmly fixed.

[0025] The drive unit includes a rear housing and a metal shaft disk located at the end of the rear housing. The drive motor is located inside the rear housing. The metal shaft disk and the metal front housing cooperate to form a metal cavity. The metal shaft disk is provided with a fixed shaft protruding toward the metal cavity. The impeller is sleeved on the fixed shaft.

[0026] To reduce the contact between the plastic parts inside the water pump and water, more components would need to be made of metal. However, this would undoubtedly increase manufacturing costs and waste materials. In this solution, the drive unit comprises two parts. The rear housing houses the drive motor, and water does not enter its interior; therefore, it can be made of plastic to save costs. The metal shaft disc is located at the end of the rear housing, forming a metal cavity with the metal front housing. All components of this metal cavity are metal, and all walls within the cavity are also made of metal. This significantly reduces the overall manufacturing cost of the water pump while minimizing contact between the plastic parts and water.

[0027] The metal front housing has a mounting position on the side facing the drive unit, and the metal shaft disk can be confined within the mounting position. The metal front housing is fixedly connected to the rear housing so that the metal front housing and the rear housing clamp and fix the metal shaft disk.

[0028] In traditional solutions, the shaft disc is typically fixed to the rear housing, and then the front housing is fixed to either the shaft disc or the rear housing to assemble the three components. This method requires two separate fixing steps, making the assembly process cumbersome and increasing the number of fastening components, thus increasing costs. In this solution, a mounting position is provided on the metal front housing. During assembly, the metal shaft disc can be simply fixed in this mounting position. At this point, the metal shaft disc is not securely connected to the metal front housing; its position is merely restricted, forming a single component. This component is then fixed to the rear housing. The fastening connection between the metal front and rear housings clamps the metal shaft disc from both sides, achieving assembly of the three components. This method eliminates the need for fixing the metal shaft disc to the rear housing, simplifying the assembly process and improving efficiency while ensuring assembly stability. Furthermore, it eliminates the need for machining a fixing structure on the metal shaft disc, reducing machining difficulty and saving costs.

[0029] The metal front shell has a surrounding wall extending outward from the metal cavity along the axial direction of the impeller around the water inlet, forming a water inlet channel, and a metal limiting member is fixed inside the water inlet channel; or, the water inlet is coaxial with the impeller, and the center of the impeller has a mating part protruding towards the water inlet, and the end of the mating part facing the metal limiting member has a contact curved surface or contact arc surface for stopping against the metal limiting member.

[0030] Metal limiting components are used to axially limit the impeller in conjunction with impeller stops. However, due to the installation position of the metal limiting component and the structure of both the impeller and the metal limiting component, severe interference or wear may occur between them during impeller rotation. In this solution, a water inlet channel is formed outside the metal front shell, and the metal limiting component is placed within the water inlet channel. This allows the metal limiting component to perform its limiting function without occupying space inside the metal cavity, making impeller installation easier and providing sufficient space for smooth impeller rotation. The impeller contacts the metal limiting component through a protruding mating part with a curved or arc-shaped structure, resulting in a smoother contact and preventing severe friction. This avoids increased impeller load, ensures smooth impeller rotation, and prevents excessive wear on both the impeller and the metal limiting component, thus extending their service life. Attached Figure Description

[0031] The accompanying drawings, which are included to provide a further understanding of the present invention and constitute a part of this invention, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0032] Figure 1 This is an exploded view of the structure of a water pump according to one embodiment of the present invention;

[0033] Figure 2 for Figure 1 Cross-sectional view of a greywater pump;

[0034] Figure 3 for Figure 2 A magnified view of area A in the middle;

[0035] Figure 4 This is a schematic diagram of the structure of the metal front shell according to one embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the metal front shell according to another embodiment of the present invention;

[0037] Figure 6 This is a cross-sectional view of a water pump according to another embodiment of the present invention;

[0038] Figure 7 for Figure 6 A magnified view of area B in the middle;

[0039] Figure 8 This is an exploded view of the water pump structure according to another embodiment of the present invention;

[0040] Figure 9 for Figure 8 Schematic diagram of the structure of the metal limiting component;

[0041] Figure 10 for Figure 8 Cross-sectional view of a medium-pressure water pump.

[0042] in:

[0043] 1 Metal front shell; 11 Metal cavity; 111 Metal cavity wall; 12 Water inlet; 13 Enclosure wall; 14 Water inlet channel; 141 First extension section; 142 Second extension section; 143 Stepped surface; 15 Limiting rib; 16 Mounting position; 17 Fixing hole;

[0044] 2. Drive unit; 21. Rear housing; 22. Metal shaft disc; 221. Fixed shaft; 23. Drive motor; 24. Active magnet;

[0045] 3 Impeller; 31 Mating part; 32 Mounting base; 33 Blade;

[0046] 4 Metal limiting component; 41 Limiting part; 42 Fixing part; 43 Stopping area; 44 Water-passing mesh; 45 Enclosed area; 46 Water-passing area. Detailed Implementation

[0047] To more clearly illustrate the overall concept of this utility model, a detailed description will be provided below with reference to the accompanying drawings.

[0048] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0049] Furthermore, it should be understood in the description of this utility model that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", 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 this utility model 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 this utility model.

[0050] In this utility model, 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 part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0051] In this invention, unless otherwise expressly specified and limited, the first feature "on" or "below" the second feature may be in direct contact with the first and second features, or indirect contact through an intermediate medium. In the description of this specification, references to terms such as "implementation," "example," "aspect," or "specific example" 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 this 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.

[0052] like Figure 1 , Figure 2 , Figure 8 , Figure 9As shown, a liquid heater includes an inner tank, a water pump, and a water outlet. The inner tank is connected to the water outlet via the water pump. The water pump includes a metal front shell 1 and a drive unit 2. The metal front shell 1 and the drive unit 2 cooperate to form a metal cavity 11. A drive motor 23 is provided inside the drive unit 2. An impeller 3 is provided inside the metal cavity 11. A drive magnet is provided on the motor shaft of the drive motor 23. A driven magnet is provided on the impeller 3. The metal front shell 1 is provided with an inlet 12 that communicates with the metal cavity 11. The liquid heater also includes a metal limiting member 4 that is separately provided from the metal front shell 1. The metal limiting member 4 is provided across the inlet 12 to limit the axial movement of the impeller 3 during operation.

[0053] In this invention, the drive motor 23 drives the driven magnet through the active magnet 24 to rotate the impeller 3, thereby achieving magnetic drive. Compared with direct drive, magnetic drive can achieve non-contact drive, so the drive motor 23 and the impeller 3 can be arranged in two separate cavities. The cavity where the impeller 3 is located (metal cavity 11) allows liquids such as water to enter, while the cavity where the drive motor 23 is located is sealed, preventing liquids from contacting the drive motor 23. This reduces the possibility of the drive motor 23 malfunctioning when exposed to water and improves its service life.

[0054] Preferably, the impeller 3 is also made of metal, and all inner walls of the metal cavity 11 are made of metal, so that all parts that the water comes into contact with after entering the metal cavity 11 are made of metal. Figure 2 As shown, the active magnet 24 is fixed to the motor shaft of the drive motor 23, and the impeller 3 covers the driven magnet (not shown in the figure). The active magnet 24 and the driven magnet attract each other to drive the impeller 3 under the action of magnetic attraction.

[0055] In this invention, the metal front shell 1 and the drive unit 2 cooperate to form a metal cavity 11. The impeller 3 is located inside the metal cavity 11. When the water pump is working, water enters the metal cavity 11 and comes into direct contact with the metal front shell 1. The metal front shell 1 is made of metal, which, compared to plastic, ensures structural strength, reduces the risk of breakage, and improves the overall service life of the water pump. Furthermore, metal has better high-temperature resistance and is more stable. When in contact with water, especially hot water, for a long time, no chemicals will dissolve into the water, thus ensuring water quality and making it safe for drinking. In this invention, based on the materials of the metal front shell 1 and the metal limiting member 4, they are designed as separate structures. They can be manufactured separately, and the metal limiting member 4 is fixed to the metal front shell 1 through subsequent assembly. Since metal is more difficult and more expensive to process than plastic, the separate components reduce the structural complexity of individual components, thereby reducing the processing difficulty of each component and improving production efficiency and yield.

[0056] It should be noted that the metal limiting component 4 and the metal front shell 1 are separate structures, meaning that they can be manufactured independently rather than being integrally formed. After they are manufactured separately, the metal limiting component 4 is fixedly connected to the metal front shell 1.

[0057] The metal limiting member 4 spans across the inlet 12, thereby completely dividing the inlet 12 into at least two flow channels. When water flows through the inlet 12, the metal limiting member 4 can cut, squeeze, and collide with the bubbles in the water flow, thereby helping the bubbles to burst and improving the bubble-breaking effect. It can be understood that "spanning" refers to the metal limiting member 4 extending radially from one end of the inlet 12 to the other end of the inlet 12.

[0058] Preferably, such as Figure 2 As shown, the inlet 12 and the impeller 3 are coaxially arranged so that the metal limiting member 4 is located on the side closer to the inlet 12 along the axial direction of the impeller 3, thus limiting the movement of the impeller 3 in the axial direction toward the inlet 12. For example, a certain gap can be reserved between the metal limiting member 4 and the impeller 3. When the impeller 3 rotates axially, if the movement exceeds the gap, it will contact the metal limiting member 4 and form a stop. Under the restriction of the metal limiting member 4, the impeller 3 cannot undergo large-scale axial movement, thereby improving the positional stability of the impeller 3 during operation and reducing the probability of scratching and wear between the impeller 3 and the inner wall of the metal front shell 1. On the one hand, this reduces the wear of the metal front shell 1 and the impeller 3, increasing their service life. On the other hand, it also avoids noise when the two collide, reducing the overall noise during operation and improving the user experience.

[0059] The specific materials of all metal parts in this invention are not limited. However, as a preferred option, each metal part may be made of food-grade 304 stainless steel, 316 stainless steel, copper, etc.

[0060] This invention does not limit the positional relationship between the metal limiting member 4 and the impeller 3 when they are assembled (when the impeller 3 is not in operation). In one embodiment, after assembly, the impeller 3 contacts the metal limiting member 4. Since the impeller 3 is in contact with the metal limiting member 4 even when not in operation, the metal limiting member 4 can stop the impeller 3 from rotating axially, thus limiting its rotation to its original position and providing a good limiting effect.

[0061] However, if the impeller 3 contacts the metal limiting member 4 when it is not in operation, although this can better limit the axial movement of the impeller 3, the impeller 3 will always be in contact with and rub against the metal limiting member 4 during rotation. This will generate noise from metal friction, and the friction will also create resistance to the rotation of the impeller 3, increasing the load on the impeller 3 and reducing its rotational efficiency. Therefore, as a preferred embodiment of this utility model, such as Figure 3 As shown, the metal cavity 11 has a metal cavity wall 111 on the side opposite to the drive unit 2, and there is an assembly gap between the impeller 3 and the metal limiting member 4. Figure 3 L1) is less than the distance between the impeller 3 and the metal cavity wall 111. Figure 3 (Middle L2).

[0062] Preferably, such as Figure 3 As shown, the metal cavity wall 111 has a structure that gradually tapers towards the inlet 12, so that the metal cavity wall 111 is a sloping structure. The distance between the impeller 3 and the metal cavity wall 111 is the distance between the impeller 3 and the metal cavity wall 111 in the direction parallel to the axis.

[0063] Specifically, such as Figure 1 , Figure 2 , Figure 3 As shown, the impeller 3 includes, in the axial direction toward the inlet 12, a mounting base 32, blades 33, and a mating part 31. The mating part 31 is located at the center of the blades 33 and protrudes toward the inlet 12. Figure 3 As shown, assembly clearance ( Figure 3 L1) refers to the distance between the mating part 31 and the metal limiting member 4 in the axial direction of the impeller 3, and the distance between the impeller 3 and the metal cavity wall 111. Figure 3 L2) is the minimum distance between the blade 33 and the metal cavity wall 111 in the direction parallel to the axis of the impeller 3.

[0064] In this embodiment, an assembly gap is designed between the impeller 3 and the metal limiting member 4. After assembly, they do not contact each other, thus providing a certain margin for the axial movement of the impeller 3. In other words, this design allows for small-amplitude axial movement of the impeller 3. Theoretically, if the metal limiting member 4 does not deform, the assembly gap is the range of axial movement that the impeller 3 can achieve. When the axial displacement of the impeller 3 is less than the assembly gap, it will not form a stop with the metal limiting member 4. At this time, the impeller 3 can rotate freely and smoothly without frictional resistance from the metal limiting member 4. However, when the axial movement of the impeller 3 increases to the point that it contacts the metal limiting member 4, they form a stop. At this time, the metal limiting member 4 restricts the axial movement of the impeller 3, preventing it from undergoing large-amplitude axial movement. Meanwhile, the assembly gap is smaller than the distance between the impeller 3 and the metal cavity wall 111, so that when the impeller 3 contacts the metal limiting member 4 to form a stop, there is still a gap between the impeller 3 and the metal cavity wall 111. This ensures that the maximum axial displacement of the impeller 3 is less than its distance from the metal cavity wall 111, thereby ensuring that the impeller 3 will not scrape or collide with the metal cavity wall 111 and reducing the possibility of scraping or colliding between the metal cavity wall 111 and the impeller 3.

[0065] Furthermore, in this embodiment, the size of the assembly gap can be adjusted by design to flexibly adjust the limiting effect on the impeller 3.

[0066] As a preferred embodiment of this utility model, such as Figure 3 , Figure 7 As shown, the metal limiting member 4 includes a limiting part 41 and a fixing part 42 located at the end of the limiting part 41. The limiting part 41 is used to limit the impeller 3, and the fixing part 42 is fixed to the metal front shell 1. There is an included angle α between the fixing part 42 and the limiting part 41, wherein 0°≤α≤180°.

[0067] Since the metal limiting member 4 and the metal front shell 1 are separate structures, they need to be fixedly connected later. However, the inner wall of the metal front shell 1 is often a non-planar structure, such as an arc or inclined surface, which makes it difficult to fix it to the metal limiting member 4. The non-planar structure also makes the contact area between it and the metal limiting member 4 small, making it difficult to guarantee the stability of the metal limiting member 4.

[0068] In this embodiment, the metal limiting member 4 includes a limiting part 41 and a fixing part 42 located at the end of the limiting part 41. The two are arranged at an angle, making the metal limiting member 4 have a bent structure. By setting the angle, the extension directions of the fixing part 42 and the limiting part 41 are set to address both the ease of fixing and the reliability of limiting. For example, the limiting part 41 can be made perpendicular to the axis of the inlet 12 so that it can reliably contact the impeller 3 and form a limiting position, making the contact between the two more stable and reducing the possibility of slippage. Similarly, the fixing part 42 can be designed at an angle that makes it easier to connect with the metal front shell 1, thereby reducing the difficulty of fixing and increasing the contact area at the connection point, thus improving the fixing effect.

[0069] It should be noted that this embodiment does not limit the bending direction of the fixing part 42. In one embodiment, such as Figure 3 As shown, the fixing part 42 can be bent toward the impeller 3. In another embodiment, as... Figure 6 , Figure 7 As shown, the fixing part 42 can also be bent in a direction away from the impeller 3. Preferably, the included angle between the fixing part 42 and the limiting part 41 is not less than 90°, for example, as shown in the figure. Figure 3 As shown, the angle between it and the limiting part 41 is greater than 90°. For example, as... Figure 7 As shown, the angle between the limiting part 41 and the limiting part 42 is 90°, that is, the limiting part 41 extends radially along the inlet 12 and the fixing part 42 extends axially along the inlet 12.

[0070] Furthermore, as a preferred embodiment, the fixing part 42 is fixed to the metal front shell 1 by welding. Of course, it can also be fixed to the metal front shell 1 by other means, such as screw fixing, etc., which are not limited here.

[0071] Understandably, the metal limiting component 4 stops and limits the impeller 3. Therefore, it is necessary to ensure both the limiting effect on the impeller 3 and the water intake efficiency of the inlet 12. At the same time, the metal limiting component 4 is also subjected to the impact force of the water flow entering from the inlet 12 and the squeezing force from the impeller 3. Therefore, the connection strength and stability between the metal limiting component 4 and the inner wall of the metal cavity 11 are also subject to high requirements.

[0072] This utility model does not limit the structure and shape of the metal limiting member 4, which can be one of the following embodiments:

[0073] Example 1: In this example, as Figures 1 to 5 As shown, the metal limiting member 4 is a strip structure. The end of the metal limiting member 4 is fixed to the metal front shell 1, and the middle region extends radially into the water inlet 12 along the water inlet 12 to stop and limit the impeller 3.

[0074] In one specific example of this embodiment, such as Figure 1 As shown, there is one metal limiting member 4. Both ends of the metal limiting member 4 are fixed to the metal front shell 1. At least a portion of the middle region of the metal limiting member 4 is coaxially arranged with the impeller 3 to limit the impeller 3.

[0075] In this example, the metal limiting member 4 is a single strip structure that extends radially along and across the inlet 12. Both ends are fixedly connected to the inner wall of the metal cavity 11, and the middle region between the two ends limits the impeller 3. This fixed-end design enhances the fixing strength of the metal limiting member 4, allowing it to stably stop the impeller 3. Simultaneously, the metal limiting member 4 divides the inlet 12 into two parts, preventing excessive obstruction and allowing water to flow through both sides of the metal limiting member 4, thus ensuring efficient water intake.

[0076] In another specific example under this embodiment, such as Figure 4 , Figure 5 As shown, the metal limiting member 4 includes a plurality of fixing parts 42 that are circumferentially spaced along the water inlet 12 and fixed to the metal front shell 1, and a limiting part 41 that extends radially inward from the fixing parts 42 along the water inlet 12. The limiting parts 41 intersect to form a stop area 43. The stop area 43 is coaxially arranged with the impeller 3 to limit the impeller 3.

[0077] The metal limiting member 4 includes multiple strip-shaped structures extending inward from different positions around the inlet 12. The limiting parts 41 intersect at the center to form a stop area 43. Compared to a single metal limiting member 4, the stop area 43 has better structural strength and can withstand greater pushing force from the impeller 3 without easily deforming, thus ensuring reliable limiting of the impeller 3. At the same time, the fixing part 42 of the metal limiting member 4 is fixed to multiple areas of the metal front shell 1, which also improves the fixing strength and stability between the metal limiting member 4 and the metal front shell 1, reducing the possibility of detachment. A water passage gap is formed between two adjacent fixing parts 42 to allow water to pass through and also to guide the water flow, making the water flow more orderly and reducing the possibility of turbulence.

[0078] For example, such as Figure 4 As shown, the metal limiting member 4 includes three fixing parts 42, which are evenly spaced along the circumference of the inlet 12 so that the included angle between two adjacent limiting parts 41 is 60°. The limiting parts 41 intersect at the center of the inlet 12, which is also the center of the impeller 3, to form a stop area 43. For example, as... Figure 5As shown, there are two metal limiting members 4 arranged in a cross shape, that is, they have four fixing parts 42. The four fixing parts 42 are evenly spaced along the circumference of the water inlet 12 so that the included angle between two adjacent limiting parts 41 is 90°. The limiting parts 41 also intersect at the center of the water inlet 12 to form a stop area 43. Of course, the number of metal limiting members 4 can also be other, and is not limited here. Those skilled in the art will also understand that the angle between the above-mentioned extensions 41 can also be unevenly distributed.

[0079] Example 2: In this example, as Figures 8 to 10 As shown, the metal limiting member 4 has a mesh structure and is provided with a water-passing mesh hole 44. The impeller 3 has a protruding mating part 31 on the side facing the water inlet 12. The opening area of ​​the water-passing mesh hole 44 is smaller than the cross-sectional area of ​​the mating part 31.

[0080] The metal limiting member 4 has a mesh structure. The opening area of ​​the water-passing mesh 44 is smaller than the cross-sectional area of ​​the mating part 31 of the impeller 3. This allows the metal limiting member 4 to also stop and limit the impeller 3 while allowing water to pass through. Water from the inlet 12 can enter the metal cavity 11 through the water-passing mesh 44, which filters out large particles of impurities in the water, preventing them from being drawn into the impeller 3 and causing it to rotate sluggishly. Simultaneously, the mating part 31 cannot pass through the water-passing mesh 44, thus forming a stop with the metal limiting member 4 and restricting the axial movement of the impeller 3. Furthermore, the impeller 3 is stopped by the protruding mating part 31 and the metal limiting member 4, preventing the end face of the impeller 3 from contacting the metal limiting member 4 and avoiding complete blockage of the water-passing mesh 44. After the mating part 31 contacts the metal limiting member 4, only a portion of the water-passing mesh 44 may be blocked, while most of the water-passing mesh 44 remains open for water flow.

[0081] This embodiment does not limit the opening form of the metal limiting member 4. In one example, the metal limiting member 4 includes a limiting part 41 and a fixing part 42 located at the end (outer periphery) of the limiting part 41, and the water-passing mesh 44 is evenly distributed throughout the limiting part 41. In another example, such as Figure 9 As shown, the central area of ​​the limiting part 41 (the area corresponding to the mating part 31) has a closed area 45, that is, no water-passing mesh 44 is provided, and the outer periphery of the closed area 45 has a water-passing area 46, and the water-passing mesh 44 is opened in the water-passing area 46.

[0082] Preferably, the metal limiting member 4 includes a limiting part 41 and a fixing part 42 located at the end of the limiting part 41. The limiting part 41 is recessed in the direction away from the impeller 3 so as to form a mating curved surface on the side of the limiting part 41 facing the impeller 3.

[0083] To ensure the reliable positioning of the metal limiting component 4 against the impeller 3, precise control of the assembly gap between them is necessary. However, due to machining and assembly errors, this gap is often difficult to control. Furthermore, the metal limiting component 4 is a thin-walled structure. When the impeller 3 comes into contact with the metal limiting component 4, the large pushing force of the impeller 3 can cause deformation of the metal limiting component 4, increasing the gap and affecting its positioning effect on the impeller 3. By recessing the limiting part 41 in a direction away from the impeller 3 to form a mating surface, the mating surface can provide some clearance for the impeller 3, allowing for more accurate design and control of the gap. Additionally, when the impeller 3 comes into contact with the metal limiting component 4, the contact force between the impeller 3 and the metal limiting component 4 is dispersed on the curved surface, thus alleviating localized stress on the limiting part 41 and reducing the possibility of deformation. Furthermore, curved structures have higher structural strength than planar structures, thus reducing the probability of deformation of the limiting part 41 and ensuring structural and positional reliability.

[0084] For example, when the metal limiting member 4 is a strip structure, the mating surface can be an arc surface; when the metal limiting member 4 is a mesh structure, the mating surface can be a spherical surface. No limitation is made here.

[0085] like Figure 2 , Figure 3 , Figure 6 , Figure 7 As shown, the shell wall of the metal front housing 1 and the drive unit 2 cooperate to form a metal cavity 11. The water inlet 12 is opened on the shell wall of the metal front housing 1, and a surrounding wall 13 protruding outward from the outer periphery of the water inlet 12 is provided to form a water inlet channel 14 communicating with the metal cavity 11. The water inlet 12 constitutes the outlet of the water inlet channel 14. This utility model does not limit the setting position of the metal limiting member 4. In one embodiment, the metal limiting member 4 is set inside the metal cavity 11 to improve the compactness of the arrangement of the metal limiting member 4 and the impeller 3, which helps to reduce the overall size of the water pump and achieve miniaturization.

[0086] As a preferred embodiment of this utility model, such as Figure 3 , Figure 7 , Figure 10 As shown, the metal front shell 1 has a surrounding wall 13 extending outward from the metal cavity 11 along the axial direction of the impeller 3 on the outer periphery of the water inlet 12. The surrounding wall 13 forms a water inlet channel 14, and the metal limiting member 4 is fixed inside the water inlet channel 14.

[0087] By forming a water inlet channel 14 on the outside of the metal front shell 1 and setting the metal limiting member 4 inside the water inlet channel 14, the metal limiting member 4 can perform the limiting function without occupying the space inside the metal cavity 11, thus making it easier to install the impeller 3 and leaving enough space for the impeller 3 to rotate, ensuring that the impeller 3 rotates smoothly.

[0088] However, the inner wall of the water inlet channel 14 is a circular surface, making it difficult to connect with the metal limiting member 4. Therefore, in a preferred embodiment of this invention, as... Figure 7 As shown, the water inlet channel 14 includes a first extension section 141 and a second extension section 142 along the axial direction of the impeller 3. The inner diameter of the first extension section 141 is larger than the inner diameter of the second extension section 142 to form a stepped surface 143 between the two. The metal limiting member 4 includes a limiting part 41 and a fixing part 42 located at the end of the limiting part 41. The extending direction of the fixing part 42 is parallel to the water inlet channel 14, and the end face of the fixing part 42 abuts against the stepped surface 143. The outer peripheral surface of the fixing part 42 abuts against the inner wall of the first extension section 141.

[0089] The extension direction of the fixing part 42 is designed to be parallel to the water inlet channel 14, so that the metal limiting member 4 can insert the fixing part 42 into the first extension section 141, so that the end face of the fixing part 42 abuts against the stepped surface 143 and the outer peripheral surface abuts against the inner wall of the first extension section 141. This not only reduces the installation difficulty of the metal limiting member 4, but also makes the fixing part 42 fixed to the water inlet channel 14 through two vertical surfaces, which greatly increases the contact area and improves the fixing stability. At the same time, the inner wall of the first extension section 141 also forms an inward clamping force on the fixing part 42, making the metal limiting member 4 more firmly fixed.

[0090] In addition, the stepped surface 143 can also limit the fixed part 42, preventing the metal limiting part 4 from moving axially along the water inlet channel 14 under the push of the impeller 3.

[0091] The fixing part 42 can be bent toward the impeller 3 or in a direction away from the impeller 3, as long as it is parallel to the water inlet channel 14.

[0092] Specifically, the outer peripheral surface of the fixing part 42 can abut against the inner wall of the first extension 141 through an interference fit, so that the first extension 141 forms an inward clamping force on the fixing part 42, thereby fixing the metal limiting member 4. Of course, the fixing part 42 can also be fastened to the first extension 141 by welding or other methods, which is not limited here. In addition, regardless of the structure of the metal limiting member 4, such as the strip structure or mesh structure in the above embodiment, the fixing part 42 can be fixed to the inner wall of the water inlet channel 14, thereby placing the metal limiting member 4 within the water inlet channel 14.

[0093] As a preferred embodiment of this utility model, such as Figure 1 , Figure 2 , Figure 8 As shown, the drive unit 2 includes a rear housing 21 and a metal shaft disk 22 located at the end of the rear housing 21. The drive motor 23 is disposed inside the rear housing 21. The metal shaft disk 22 and the metal front housing 1 cooperate to form a metal cavity 11. The metal shaft disk 22 is provided with a fixed shaft 221 protruding toward the metal cavity 11, and the impeller 3 is sleeved on the fixed shaft 221. The metal shaft disk 22 and the metal front housing 1 can be sealed by a sealing ring, or by welding, ultrasonic welding, or other methods.

[0094] To reduce the contact between the plastic parts inside the water pump and water, more components would need to be made of metal. However, this would undoubtedly increase manufacturing costs and waste materials. In this embodiment, the drive unit 2 includes two parts. The rear housing 21 houses the drive motor 23, and water does not enter its interior; therefore, it can be made of plastic to save costs. The metal shaft disc 22 is located at the end of the rear housing 21 and mates with the metal front housing 1 to form a metal cavity 11. All components of the metal cavity 11 are metal, and all walls inside the metal cavity 11 are also made of metal. This significantly reduces the overall manufacturing cost of the water pump while minimizing contact between the plastic parts and water.

[0095] This embodiment does not limit the assembly method of the metal shaft disk 22. In one embodiment, the metal shaft disk 22 is fixed to the rear shell 21, and then the metal front shell 1 is fixed to the metal shaft disk 22 or the rear shell 21, so that the metal shaft disk 22 is located between the metal front shell 1 and the rear shell 21.

[0096] In another embodiment, such as Figure 2 , Figure 4 , Figure 5 As shown, a mounting position 16 is provided on the side of the metal front shell 1 facing the drive unit 2, and the metal shaft disk 22 can be confined within the mounting position 16. The metal front shell 1 is fixedly connected to the rear shell 21 so that the metal front shell 1 and the rear shell 21 clamp and fix the metal shaft disk 22.

[0097] In this embodiment, a mounting position 16 is provided on the metal front shell 1. During assembly, the metal shaft disk 22 can be simply fixed in the mounting position 16. At this time, the metal shaft disk 22 is not tightly connected to the metal front shell 1, but only its position is restricted, making the two form a component. Then, this component is fixed together to the rear shell 21. Through the tight connection between the metal front shell 1 and the rear shell 21, the metal front shell 1 and the rear shell 21 clamp the metal shaft disk 22 from both sides, realizing the assembly of the three components. This method can eliminate the need to fix the metal shaft disk 22 to the rear shell 21. While ensuring assembly stability, it simplifies the assembly steps, improves assembly efficiency, and eliminates the need to process a fixing structure on the metal shaft disk 22, reducing processing difficulty and saving costs.

[0098] Specifically, such as Figure 4 , Figure 5 As shown, the end face of the metal front housing 1 facing the metal shaft disk 22 is provided with multiple limiting ribs 15. The limiting ribs 15 are arranged at intervals along the circumference of the metal shaft disk 22 to form a mounting position 16. During assembly, the metal shaft disk 22 is placed within the mounting position 16. At this time, the limiting ribs 15 surround the outer periphery of the metal shaft disk 22, thereby fixing the position of the metal shaft disk 22 relative to the metal front housing 1. Figure 4 , Figure 5 As shown, the metal front shell 1 is also provided with a fixing hole 17 on the outside of the mounting position 16. The metal front shell 1 and the rear shell 21 are fastened together by fasteners such as screws passing through the fixing hole 17, and the two clamp the metal shaft disk 22 under the action of pre-tightening force.

[0099] Preferably, such as Figure 3 , Figure 7 , Figure 10 As shown, the inlet 12 is coaxially arranged with the impeller 3. The center of the impeller 3 is provided with a mating part 31 protruding towards the inlet 12. The end of the mating part 31 facing the metal limiting member 4 is provided with a contact curved surface or contact arc surface for stopping with the metal limiting member 4.

[0100] The impeller 3 contacts the metal limiting member 4 through the protruding mating part 31, and the mating part 31 is provided with a curved or arc-shaped structure, which makes the contact between the two more gentle and does not produce severe friction, thereby avoiding an increase in the load on the impeller 3, allowing the impeller 3 to rotate smoothly, and preventing excessive wear of the impeller 3 and the metal limiting member 4, thus improving their service life.

[0101] In one specific embodiment, the end of the mating part 31 facing the metal limiting member 4 has a spherical structure, and the mating part 31 is coaxially arranged with the impeller 3. Of course, the mating part 31 can also be offset from the axis of the impeller 3, as long as it protrudes from the end face of the impeller 3, which is not limited here.

[0102] For any parts not mentioned in this utility model, existing technologies can be used or referenced.

[0103] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0104] The above description is merely an embodiment of this utility model and is not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this utility model should be included within the scope of the claims of this utility model.

Claims

1. A liquid heater, comprising an inner tank, a water pump, and a water outlet, wherein the inner tank is connected to the water outlet via the water pump, characterized in that, The water pump includes a metal front housing and a drive unit. The metal front housing and the drive unit cooperate to form a metal cavity. A drive motor is installed inside the drive unit. An impeller is installed inside the metal cavity. A drive magnet is installed on the motor shaft of the drive motor. A driven magnet is installed on the impeller. The metal front housing is provided with a water inlet communicating with the metal cavity. The liquid heater also includes a metal limiting member that is separately installed from the metal front housing. The metal limiting member is installed across the water inlet to restrict the impeller from moving axially during operation.

2. The liquid heater according to claim 1, characterized in that, The metal cavity has a metal cavity wall on the side opposite to the drive unit, and there is an assembly gap between the impeller and the metal limiting member, which is smaller than the distance between the impeller and the metal cavity wall.

3. The liquid heater according to claim 1, characterized in that, The metal limiting member includes a limiting part and a fixing part located at the end of the limiting part. The limiting part is used to limit the impeller. The fixing part is fixed to the metal front shell. There is an included angle α between the fixing part and the limiting part, wherein 0°≤α≤180°.

4. The liquid heater according to claim 1, characterized in that, The metal limiting member is a strip-shaped structure, and there is only one metal limiting member. Both ends of the metal limiting member are fixed to the metal front shell, and at least a portion of the middle region of the metal limiting member is coaxially arranged with the impeller to limit the movement of the impeller; or... The metal limiting member includes a plurality of fixing portions that are circumferentially spaced along the water inlet and fixed to the metal front shell, and a limiting portion that extends radially inward from the fixing portions along the water inlet. The limiting portions intersect to form a stop area, and the stop area is coaxially arranged with the impeller to limit the impeller.

5. The liquid heater according to claim 1, characterized in that, The metal limiting member has a mesh structure and is provided with water-passing mesh holes. The impeller has a mating part protruding on the side facing the water inlet. The opening area of ​​the water-passing mesh holes is smaller than the cross-sectional area of ​​the mating part.

6. The liquid heater according to claim 1, characterized in that, The metal limiting member includes a limiting part and a fixing part located at the end of the limiting part. The limiting part is recessed in a direction away from the impeller to form a mating curved surface on the side of the limiting part facing the impeller.

7. The liquid heater according to claim 1, characterized in that, The metal front shell is provided with a surrounding wall extending outward from the metal cavity along the axial direction of the impeller on the outer periphery of the water inlet. The surrounding wall forms a water inlet channel. The water inlet channel includes a first extension section and a second extension section along the axial direction of the impeller. The inner diameter of the first extension section is larger than the inner diameter of the second extension section to form a stepped surface between them. The metal limiting member includes a limiting part and a fixing part located at the end of the limiting part. The extending direction of the fixing part is parallel to the water inlet channel, and the end face of the fixing part abuts against the stepped surface. The outer peripheral surface of the fixing part abuts against the inner wall of the first extension section.

8. The liquid heater according to claim 1, characterized in that, The drive unit includes a rear housing and a metal shaft disk located at the end of the rear housing. The drive motor is disposed inside the rear housing. The metal shaft disk cooperates with the metal front housing to form the metal cavity. The metal shaft disk is provided with a fixed shaft protruding toward the metal cavity. The impeller is sleeved on the fixed shaft.

9. The liquid heater according to claim 8, characterized in that, The metal front housing has a mounting position on the side facing the drive unit, and the metal shaft disk can be confined within the mounting position. The metal front housing is fixedly connected to the rear housing so that the metal front housing and the rear housing clamp and fix the metal shaft disk.

10. The liquid heater according to claim 1, characterized in that, The metal front casing has a surrounding wall extending axially from the impeller towards the outside of the metal cavity around the water inlet, the surrounding wall forming a water inlet channel, and the metal limiting member fixed within the water inlet channel; or, The water inlet is coaxially arranged with the impeller, and the center of the impeller is provided with a mating part protruding towards the water inlet. The end of the mating part facing the metal limiting member is provided with a contact curved surface or a contact arc surface for stopping with the metal limiting member.

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