An electric water pump

Abstract

The utility model discloses an electric water pump, it includes by rigid wear -resisting material quality to make the connecting piece and lower limit piece, connecting piece and the cavity wall solid of impeller cavity are connected and are equipped with the connecting body of the first end of the pump shaft, and the connecting body is solid connected with the pump shaft and is equipped with the limit wall of directly abutting with the upper end of rotating sleeve, and the limit wall is used for the upward movement limit of rotating sleeve, and the projection of limit wall on the projection plane perpendicular to the pump shaft covers the projection of rotating sleeve and the outer contour projection is located outside the projection of rotating sleeve, and the lower limit piece is solid connected with the second end of pump shaft to limit the downward movement of rotating sleeve. The application has high assembly qualified rate and longer service life.

Description

Technical Field

[0001] This utility model relates to the field of water pumps, specifically to an electric water pump. Background Technology

[0002] In the prior art, centrifugal electric water pumps utilizing permanent magnet brushless motors are widely used in the cooling water circulation systems of the automotive industry. These electric water pumps generally include a housing, pump shaft, brushless motor, control board, and impeller. The housing is typically composed of an upper housing, a middle housing, and a lower housing fixedly connected together. The upper housing has an impeller cavity, an inlet, and an outlet; the inlet is axially connected to the impeller cavity, and the outlet is tangentially connected to the impeller cavity. The middle housing has a rotor cavity, and the upper and middle housings are watertightly connected to ensure axial communication between the impeller cavity and the rotor cavity. The middle and lower housings are fixedly connected and enclose an electrical control cavity, which is watertightly isolated from the rotor cavity. The impeller is placed inside the impeller cavity, the rotor of the brushless motor is placed inside the rotor cavity, and the stator of the brushless motor (including the stator section and winding section) is arranged around the rotor cavity and fixedly connected to the housing. The control board, used to control the stator, is placed inside the control cavity. The pump shaft, rotor, and impeller are integrally fixed. The pump shaft, positioned between the rotor and impeller, is supported by a bearing fixed to a support plate, which is itself fixed to the stator. The lower end of the pump shaft is supported by a bearing fixed to the lower housing. Washers, typically made of stainless steel or ceramic, are usually placed between the pump shaft and the bearings. These washers adjust clearance, rotor position, and provide a smooth rotating friction surface for the rotor bearings, improving lifespan and reducing frictional losses. The integrally fixed pump shaft, rotor, and impeller are driven by a brushless motor, pumping water from the inlet through the impeller to the outlet. However, in practice, it has been found that the assembly pass rate of electric water pumps is low, and the rotor of electric water pumps is prone to rotational failure. Utility Model Content

[0003] The purpose of this utility model is to overcome the above-mentioned defects or problems in the background art and provide an electric water pump with a high assembly qualification rate and a longer service life.

[0004] To achieve the above objectives, the present invention and its preferred embodiments adopt the following technical solutions, but the embodiments are not limited to the following solutions:

[0005] The first technical solution and its related embodiments provide an electric water pump, which has an impeller cavity, a rotor cavity, an electrical control cavity, an inlet, and an outlet. It includes a pump shaft, an impeller, and a rotor. The inlet and outlet are connected to the impeller cavity. A first end of the pump shaft is located in the impeller cavity, and a second end is located in the rotor cavity. The impeller is located in the impeller cavity and is fixedly connected to the rotor. The rotor is located in the rotor cavity and includes a rotating sleeve. The rotating sleeve is sleeved on the pump shaft and has a clearance fit with the pump shaft to allow axial sliding relative to the pump shaft. It also includes... : A connecting member, made of rigid wear-resistant material, is fixedly connected to the cavity wall of the impeller cavity and has a connecting body sleeved on the first end of the pump shaft. The connecting body is fixedly connected to the pump shaft and has a limiting wall that directly abuts against the upper end of the rotating sleeve. The limiting wall is used to limit the upward movement of the rotating sleeve, and the projection of the limiting wall on the projection plane perpendicular to the pump shaft covers the projection of the rotating sleeve, and the outer contour projection is located outside the projection of the rotating sleeve; and a lower limiting member, which is fixedly connected to the second end of the pump shaft to limit the downward movement of the rotating sleeve.

[0006] Based on the first technical solution, a second technical solution is also provided. In the second technical solution and its related embodiments, the connector is provided with at least two connecting ribs, and the connector body is generally in the shape of a bullet facing the water inlet; one end of the connecting rib is fixed to the connector body, and the other end is fixed to the cavity wall of the impeller cavity, and each connecting rib is arranged circumferentially; the lower end face of the connector body forms the limiting wall.

[0007] Based on the second technical solution, a third technical solution is also provided. In the third technical solution and its related embodiments, the connecting body is provided with an upper connecting part and a lower connecting part that are connected as one piece. The upper connecting part is fixedly connected to the connecting rib, and the ratio of the axial length to the outer diameter of the lower connecting part is between 0.25 and 0.85.

[0008] Based on the first technical solution, a fourth technical solution is also provided. In the fourth technical solution and its related embodiments, the connecting body is a cylindrical shape with the opening facing downward, and the first end of the pump shaft is inserted into the cylinder formed by the connecting body and abuts against the bottom of the cylinder.

[0009] Based on the fourth technical solution, a fifth technical solution is also provided. In the fifth technical solution and its related embodiments, the pump shaft is provided with a water passage along its extension direction; the bottom of the connecting body is provided with a through hole, and the inner diameter of the through hole is larger than the inner diameter of the water passage.

[0010] Based on the fourth technical solution, a sixth technical solution is also provided. In the sixth technical solution and its related embodiments, the cylinder formed by the connecting body radially limits the first end of the pump shaft, and the upper and lower ends of the cylinder form a radial gap with the first end of the pump shaft.

[0011] Based on the first technical solution, a seventh technical solution is also provided. In the seventh technical solution and its related embodiments, the roughness of the limiting wall does not exceed Ra0.2.

[0012] Based on the first technical solution, an eighth technical solution is also provided. In the eighth technical solution and its related embodiments, the lower limiting member is annular and is press-fitted to the second end of the pump shaft. The ratio of its axial length to its outer diameter is between 0.25 and 0.85.

[0013] Based on any one of the first to eighth technical solutions, a ninth technical solution is also provided. In the ninth technical solution and its related embodiments, a housing is further provided. The housing includes an upper housing, a middle housing, and a lower housing. The upper housing is watertightly fixed to the middle housing, and the lower housing is fixedly fixed to the middle housing. The impeller cavity is formed in the upper housing, and the rotor cavity is formed in the middle housing. The middle housing and the lower housing together form the electrical control cavity, which is watertightly isolated from the rotor cavity. The upper housing is made of plastic material, and the connector and the upper housing insert are injection molded integrally. Alternatively, the upper housing and the connector are both made of metal material, and the connector is welded to the upper housing.

[0014] Based on the ninth technical solution, a tenth technical solution is also provided. In the tenth technical solution and its related embodiments, a stator and an electronic control board are further included. The stator is fixedly connected to the middle housing and surrounds the rotor cavity. The electronic control board is installed in the electronic control cavity and electrically connected to the stator to control the stator. The pump shaft is provided with a water passage along its extension direction. A high-pressure zone is formed between the impeller and the cavity wall of the impeller cavity. The high-pressure zone is connected to a low-pressure zone near the water inlet through the rotor cavity and the water passage. A heat dissipation wall is formed on the side cavity wall of the rotor cavity. A water passage gap is formed between the heat dissipation wall and the rotor. The water passage gap is used to connect the high-pressure zone and the water passage.

[0015] As can be seen from the above description of the present invention and its preferred embodiments, compared with the prior art, the technical solution of the present invention and its preferred embodiments have the following beneficial effects due to the adoption of the following technical means:

[0016] Through continuous observation, experimentation, and research, the applicant has determined that the technical problems arising from the existing solutions, namely the low assembly pass rate of electric water pumps and the tendency for the pump rotor to fail due to rotation, are as follows: ceramic washers are prone to cracking and are difficult to process. Stainless steel washers, being relatively thin and small, are difficult to maintain a long lifespan due to the rotational friction of the rotor bearing. After wear, the washers are prone to detaching and jamming the rotor, leading to pump failure. Furthermore, because the washers are thin and small, their presence is easily overlooked during assembly, resulting in washers being easily omitted, over-installed, or misaligned.

[0017] In the first technical solution, since the connector is made of a rigid wear-resistant material, which here means "ultimate tensile strength exceeding 480MPa, no rust after more than 48 hours of neutral salt spray testing, and Vickers hardness exceeding HV". The 120" connector can be made of metal, metal-based composite material, or high-performance engineering plastics such as PEEK. The connector possesses high strength, corrosion resistance, high hardness, and lubricity, making it resistant to wear. Furthermore, the connector is fixedly connected to the impeller cavity wall, ensuring structural stability. The connector includes a connecting body sleeved on the first end of the pump shaft. This connecting body has a limiting wall that directly abuts against the upper end of the rotating sleeve. The limiting wall limits the upward movement of the rotating sleeve, and its projection on the plane perpendicular to the pump shaft covers the projection of the rotating sleeve, with its outer contour projection outside the projection of the rotating sleeve. This design offers several advantages: firstly, the integrated limiting wall made of rigid, wear-resistant material directly replaces the traditional gasket, eliminating the need for a gasket at the upper end of the rotating sleeve. This avoids the risk of missing, over-installed, or misaligned gaskets, and also prevents worn gaskets from falling off and becoming stuck between the rotating sleeve and pump shaft, between the upper housing and impeller, or between the stator and rotor, causing the rotor to jam. The first is the failure of the rotating sleeve. The second is the use of highly wear-resistant materials to ensure no debris falls off during long-term operation. The third is that this also means that the ring width of the limiting wall is greater than the ring width of the rotating sleeve. When the ring width of the limiting wall is the same as the ring width of the rotating sleeve, there is a deviation between the axis of the rotating sleeve and the axis of the connecting body after assembly. During the rotor rotation, the upper end of the rotating sleeve is easily worn and unevenly due to the fact that the material of the rotating sleeve is generally not wear-resistant. If a depression is formed, when the worn part gets stuck between the rotating sleeve and the pump shaft, it is easy to cause the rotor to jam and fail to rotate. In this technical solution, the ring width of the limiting wall is greater than the ring width of the rotating sleeve, and the projection of the limiting wall covers the projection of the rotating sleeve, so that the upper end of the rotating sleeve can be worn evenly. When it is worn evenly, the upper part of the rotating sleeve falls off in powder form and enters the rotor cavity, and is carried away by the coolant in the rotor cavity. It is not easy to get stuck between the rotating sleeve and the pump shaft, between the upper housing and the impeller, or between the stator and the rotor, causing the rotor to jam and fail to rotate.

[0018] The rotating sleeve is designed for axial sliding relative to the pump shaft, making it easier to assemble the rotor and impeller as a whole onto the pump shaft. The limiting wall restricts the upward movement of the rotor and impeller as a whole, allowing the connector to perform more functions beyond simply connecting the pump shaft, resulting in a simpler structure. Simultaneously, because the limiting wall restricts the upward movement of the rotor and impeller as a whole, the fixed position of the pump shaft to the housing is closer to the upper part of the rotor, which is beneficial for suppressing the deflection of the pump shaft. The lower limiting component restricts the downward movement of the rotor and impeller as a whole, preventing the rotor and impeller from impacting the connector due to excessive upward travel during rotation. This is beneficial for reducing noise and increasing lifespan, and also solves the problem of the rotor, which moves freely along the pump shaft axis during assembly, being magnetically attracted away.

[0019] Furthermore, the first end of the pump shaft is fixed to the wall of the impeller cavity via a connector. Therefore, when the impeller rotates, the pump shaft is fixed to the casing very close to the upper part of the rotor. Compared to the prior art where the pump shaft is fixed to the casing in the rotor cavity, the pump shaft deflection caused by the centroid shift of the rotor and impeller during operation is smaller, resulting in less pump shaft vibration amplitude and reduced noise during operation. Additionally, the connecting piece is easier to machine with compared to the upper casing, and the offset between the pump shaft axis and the central axis of the impeller cavity is smaller.

[0020] In the second technical solution and its preferred embodiment, the connecting body for fixed connection with the pump shaft is connected to the upper housing via connecting ribs. These ribs are distributed circumferentially, and the spacing between them allows water to flow smoothly from the inlet into the impeller. The circumferential distribution of the connecting ribs also ensures the positional accuracy of the connecting body within the impeller cavity, minimizing the offset between the axis of the pump shaft connected to the connecting body and the central axis of the impeller cavity, thus effectively improving the operating efficiency of the electric water pump. The connecting body is generally bullet-shaped, facing the inlet, with its upper surface roughly conical or dome-shaped. This shape helps reduce the flow resistance of water flowing from the inlet to the impeller, improving the operating efficiency of the electric water pump. Compared to a solution where the connecting body and the first end of the pump shaft mate to form a bullet shape facing the inlet, there is no need to consider the matching of the two components during processing, resulting in lower processing precision requirements and lower overall cost.

[0021] In the third technical solution and its preferred embodiment, the ratio of the axial length to the outer diameter of the lower connecting part is between 0.25 and 0.85. The lower connecting part has a relatively long axial length, which on the one hand improves the strength of the lower connecting part, and on the other hand ensures that even if the lower connecting part is worn, the limiting wall can still limit the upward movement of the rotating sleeve, thus ensuring the normal operation of the electric water pump and extending the service life of the electric water pump.

[0022] In the fourth technical solution and its preferred embodiment, the connecting body is a cylindrical shape with the opening facing downwards. The first end of the pump shaft is inserted into the cylinder of the connecting body and abuts against the bottom of the cylinder. This is beneficial for the initial positioning of the first end of the pump shaft during the assembly of the electric water pump and for the assembly of the lower limiting component at the second end of the pump shaft.

[0023] In the fifth technical solution and its preferred embodiment, the inner diameter of the through hole is larger than the inner diameter of the water passage. Compared with the inner diameter of the through hole being the same as the inner diameter of the water passage, it is beneficial to avoid the assembly difficulties caused by the inconsistency between the axis of the through hole and the axis of the water passage when positioning the connector and the pump shaft by means of components such as positioning pins, thereby improving assembly efficiency.

[0024] In the sixth technical solution and its preferred embodiment, the cylinder of the connecting body radially limits the first end of the pump shaft, and the upper and lower ends of the cylinder form a radial gap with the first end of the pump shaft, which is beneficial for the first end of the pump shaft to be inserted into the connecting body and to cooperate with the radial limit of the connecting body, further reducing assembly resistance and improving assembly efficiency.

[0025] In the seventh technical solution and its preferred embodiment, the roughness of the limiting wall does not exceed Ra0.2, which helps to reduce the resistance when the rotating sleeve rotates, avoid wear between the rotating sleeve and the limiting wall, and extend the service life.

[0026] In the eighth technical solution and its preferred embodiment, the lower limit component and the second end of the pump shaft are press-fitted together. Compared with the existing technology that generally uses a snap ring to form the lower limit component, the lower limit component is less likely to fall off, thus preventing frequent impact damage to the connecting parts. The ratio of the axial length of the lower limit component to its outer diameter is between 0.25 and 0.85. The axial length of the lower limit component is longer than that of a regular washer, making it more wear-resistant.

[0027] In the ninth technical solution and its preferred embodiment, when the upper housing is made of plastic, the connector and the upper housing insert are injection molded as one piece, which reduces costs and better ensures the positional accuracy of the connector in the impeller cavity. This makes the deviation between the axis of the pump shaft connected to the connector and the central axis of the impeller cavity smaller, which is beneficial to improving the operating efficiency of the electric water pump. When both the upper housing and the connector are made of metal, the connector is welded to the upper housing. This not only ensures the positional accuracy of the connector in the impeller cavity, but the metal upper housing also has higher strength, which is more conducive to avoiding the vibration of the impeller and rotor being transmitted to the upper housing through the pump shaft, thus preventing the upper housing from cracking.

[0028] In the tenth technical solution and its preferred embodiment, the pump shaft is provided with a water passage along its extension direction. The high-pressure zone is connected to the low-pressure zone through the rotor cavity via the water passage, which can establish an internal circulation cooling channel inside the electric water pump. This allows water to flow from the high-pressure zone to the low-pressure zone through the internal circulation cooling channel, forming an internal circulation cooling water flow, which is beneficial for heat dissipation of the stator and the electronic control board. It should be understood that although the internal circulation cooling water flow may reduce the operating efficiency of the electric water pump, effective heat dissipation can improve the service life of the electric water pump. A water passage gap is formed between the heat dissipation wall and the rotor. The internal circulation cooling water flows through the water passage gap, making it easier to carry away the heat generated by the stator during the operation of the electric water pump, further improving the heat dissipation efficiency of the electric water pump. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a top view of the electric water pump according to an embodiment of this application;

[0031] Figure 2 for Figure 1 Sectional view along the AA direction;

[0032] Figure 3 for Figure 2 An enlarged diagram in Part A;

[0033] Figure 4 This is an exploded perspective view of the electric water pump according to an embodiment of this application.

[0034] Explanation of key figure labels:

[0035] Housing 10; Upper housing 11; Bolt hole 111; Middle housing 12; Through hole 121; Annular groove 122; Lower housing 13; Insertion part 131; Abutment wall 132; Heat dissipation wall 14; Heat conduction wall 15; Impeller cavity 01; Rotor cavity 02; Electrical control cavity 03; Inlet 04; Outlet 05; Connector 20; Connector body 21; Limiting wall 211; Through hole 212; Upper connecting part 213; Lower connecting part 214; Connecting rib 22; Embedded part 221; Pump shaft 30; Water passage 31; Impeller 40; Rotor 50; Rotor part 51; Rotating sleeve 52; Stator 60; Electrical control board 70; Lower limiting part 80. Detailed Implementation

[0036] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are preferred embodiments of the present utility model and should not be considered as excluding other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0037] Unless otherwise expressly defined, the use of terms such as "first," "second," or "third" in the claims, description, and drawings of this utility model is for distinguishing different objects and not for describing a specific order.

[0038] Unless otherwise expressly defined, in the claims, description, and accompanying drawings of this utility model, the use of directional terms such as "center," "lateral," "longitudinal," "horizontal," "vertical," "top," "bottom," "inner," "outer," "upper," "lower," "front," "rear," "left," "right," "clockwise," and "counterclockwise" to indicate orientation or positional relationships is based on the orientation and positional relationships shown in the accompanying drawings and is only for the convenience of describing this utility model and simplifying the description. It does 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, and therefore should not be construed as limiting the specific protection scope of this utility model.

[0039] Unless otherwise expressly defined, the terms "fixed connection" or "fixed connection" used in the claims, description and drawings of this utility model shall be interpreted broadly to refer to any connection in which there is no displacement or relative rotation relationship between the two parties, including non-removable fixed connection, detachable fixed connection, integral connection and fixed connection through other devices or components.

[0040] In the claims, description and accompanying drawings of this utility model, the terms "comprising", "having", and variations thereof are used to mean "including but not limited to".

[0041] In the claims and description, unless otherwise specified, the term "have" means that a technical feature that follows is part of a technical feature that precedes it.

[0042] Unless otherwise specified in the claims and description, the term "stator" includes not only the stator as understood by a person skilled in the art, but also the windings. That is, the stator includes a stator section and a winding section.

[0043] Unless otherwise specified in the claims and description, the term "watertight" refers to a liquid seal, which is commonly known to those skilled in the art to be achieved by conventional means such as sealing rings or sealing cups.

[0044] Unless otherwise specified in the claims and description, the term "insert injection molding" refers to a process in which two parts are tightly joined together and cannot be disassembled after injection molding by inserting components during the injection process.

[0045] Unless otherwise specified in the claims and description, the term "attached" means that the two are bonded together either directly or indirectly (e.g., through a thermally conductive material).

[0046] See Figure 1-4 , Figure 1-4 An electric water pump is shown, which includes a housing 10, a connector 20, a pump shaft 30, an impeller 40, a brushless motor, an electronic control board 70, and a lower limit member 80.

[0047] like Figure 2 As shown, the housing 10 includes an upper housing 11, a middle housing 12, and a lower housing 13. The upper housing 11 has an impeller cavity 01, an inlet 04, and an outlet 05. The impeller cavity 01 opens downwards, the inlet 04 axially connects to the top of the impeller cavity 01, and the outlet 05 tangentially connects to the impeller cavity 01. The middle housing 12 has a rotor cavity 02. The rotor cavity 02 opens upwards and has side walls, which form a heat dissipation wall 14. The upper housing 11 and the middle housing 12 are watertightly connected by a sealing ring and bolts. After the upper housing 11 and the middle housing 12 are fixedly connected, the impeller cavity 01 axially connects to the rotor cavity 02. The lower housing 13 is friction-welded to the middle housing 12. After the lower housing 13 and the middle housing 12 are fixedly connected, they enclose an electrical control cavity 03. The electrical control cavity 03 is adjacent to the rotor cavity 02 and axially away from the impeller cavity 01. The cavity wall between the rotor cavity 02 and the electrical control cavity 03 forms a heat-conducting wall 15. The minimum thickness of the heat-conducting wall 15 is 0.4 mm, and in practical applications, the maximum thickness of the heat-conducting wall 15 is 1.5 mm. Therefore, the housing 10 is provided with a water inlet 04, a water outlet 05, an impeller cavity 01, a rotor cavity 02, and an electrical control cavity 03.

[0048] like Figure 2-4 As shown, the connector 20 has a connector 21 and at least two connecting ribs 22. In this embodiment, there are four connecting ribs 22. The connector 21 is generally bullet-shaped, facing the inlet 04. One end of the connecting rib 22 is fixed to the connector 21, and the other end is fixed to the cavity wall of the impeller cavity 01. Specifically, one end of each connecting rib 22 is fixed to the outer edge of the connector 21, and the other end is fixed to the upper housing 11 near the inlet 04, i.e., to the cavity wall of the impeller cavity 01. Each connecting rib 22 is arranged circumferentially. In this embodiment, each connecting rib 22 has a horizontally extending insert 221 at the end away from the connector 21. The connector 21 is sleeved on the first end of the pump shaft 30 and fixed to the pump shaft 30, thereby making the first end of the pump shaft 30 fixed to the upper housing 11 through the connector 20.

[0049] In this embodiment, the connecting body 21 is also cylindrical with an opening facing downwards for the pump shaft 30 to be inserted. The bottom of the cylinder has a through hole 212, the inner diameter of which is larger than the inner diameter of the water passage 31 described below. The connecting body 21 has a limiting wall 211 that directly abuts against the upper end of the rotating sleeve 52 described below. The lower end face of the connecting body 21 forms the limiting wall 211, which is formed on the end face of the cylinder's open end. The projection of the limiting wall 211 onto the projection plane perpendicular to the pump shaft 30 covers the projection of the rotating sleeve 52 described below, and its outer contour projection is outside the projection of the rotating sleeve 52. That is, the circumferential width of the limiting wall 211 is larger than the circumferential width of the rotating sleeve 52. For example, the outer contour of the limiting wall 211 extends radially out of the rotating sleeve 52 by approximately 0.5 mm. The roughness of the limiting wall 211 does not exceed Ra0.2, and the roughness is measured according to ISO 4287 standard. See also... Figure 3 The connector 21 is provided with an upper connecting part 213 and a lower connecting part 214 that are integrated together. The upper connecting part 213 is fixedly connected to the connecting rib 22. The ratio of the axial length to the outer diameter of the lower connecting part 214 is between 0.25 and 0.85. For example, the ratio of the axial length to the outer diameter of the lower connecting part 214 is about 77%.

[0050] In this embodiment, the connector 20 is made of a rigid wear-resistant material. Here, "rigid wear-resistant material" refers to a material with an ultimate tensile strength exceeding 480 MPa, no rust after more than 48 hours of neutral salt spray testing, and a Vickers hardness exceeding HV 120. This material can be metal, metal-based composite material, or high-performance engineering plastics such as PEEK. In one embodiment, the upper housing 11 is made of plastic. The connector 20 and the upper housing 11 are injection molded using inserts. During the injection molding of the upper housing 11, the insert portion 221 of the connector 20 is placed into the mold, making the upper housing 11 and the connector 20 insert integrally molded. In another embodiment, both the upper housing 11 and the connector 20 are made of metal. A groove is formed on the upper housing 11 corresponding to each insert portion 221. The insert portion 221 is inserted into the groove and welded to the upper housing 11, thereby welding the connector 20 to the upper housing 11.

[0051] like Figure 2As shown, the first end of the pump shaft 30 is located in the impeller cavity 01 and faces the inlet 04 axially, while the second end of the pump shaft 30 is located in the rotor cavity 02 and suspended above the heat-conducting wall 15. In this embodiment, the first end of the pump shaft 30 is inserted into the cylinder formed by the connecting body 21 and abuts against the bottom of the cylinder. The pump shaft 30 can be fixed to other parts of the connecting body 21 by interference fit, or by other methods such as bonding, screwing, or embedding, which are well known to those skilled in the art. Therefore, in this embodiment, the pump shaft 30 is fixed relative to the housing 10. In this embodiment, the cylinder formed by the connecting body 21 radially limits the first end of the pump shaft 30, and both the upper and lower ends of the cylinder form radial gaps with the first end of the pump shaft 30. Specifically, the outer diameter of the upper end of the pump shaft 30 gradually decreases from bottom to top, while the inner diameter of the lower end of the cylinder gradually increases from top to bottom, thereby forming radial gaps between both the upper and lower ends of the cylinder and the first end of the pump shaft 30. The pump shaft 30 has a water passage 31 extending through the entire pump shaft 30 along its extension direction, and the water passage 31 is correspondingly connected to the through hole 212. Therefore, the first end of the pump shaft 30 is fixed to the cavity wall of the impeller cavity 01 through the connector 20. In this embodiment, the first end of the pump shaft 30 is fixed to the connector 21, and the fixed position is located inside the impeller cavity 01. In other embodiments, the connector 21 can also be fixed to other parts of the pump shaft 30 located inside the impeller cavity 01 except for the first end. In this embodiment, the connector 21 is sleeved on the first end of the pump shaft 30 and is generally bullet-shaped facing the water inlet 04. Its upper surface is roughly conical or dome-shaped. This shape helps to reduce the flow resistance of water flowing from the water inlet 04 to the impeller 40. In this embodiment, the pump shaft 30 can be made of plastic or metal.

[0052] like Figure 2 As shown, the impeller 40 rotates relative to the pump shaft 30 within the impeller cavity 01 about the rotation axis defined by the pump shaft 30. The electric water pump pressurizes the water or liquid flow input from the inlet 04 and outputs it to the outlet 05 through the rotation of the impeller 40. In this embodiment, when the impeller 40 rotates in the impeller cavity 01, a high-pressure zone is formed between the impeller 40 and the cavity wall of the impeller cavity 01. Specifically, there is a gap between the outer edge of the impeller 40 and the side cavity wall of the impeller cavity 01, and this gap forms the high-pressure zone. Correspondingly, when the impeller 40 rotates in the impeller cavity 01, a low-pressure zone is formed in the area near the inlet 04. When the electric water pump is used to establish a circulating water flow, the rotation of the impeller 40 causes the pressure at the outlet 05 to be higher than the pressure at the inlet 04, causing the circulating water pump to pump water from the outlet 05 back to the inlet 04.

[0053] like Figure 2As shown, the brushless motor includes a stator 60 and a rotor 50. The stator 60 includes a stator section and a winding section. The stator 60 is fixedly connected to the middle housing 12 and surrounds the rotor cavity 02. The middle housing 12 also surrounds the stator 60. The stator 60 is watertight from the rotor cavity 02. The rotor 50 is located in the rotor cavity 02 and is rotatably connected to the pump shaft 30. The rotor 50 is sleeved on the pump shaft 30. In this embodiment, the rotor 50 includes a rotor section 51 and a rotating sleeve 52 fixedly connected to each other. The rotor section 51 and the stator 60 together constitute the brushless motor. The rotor section 51 is generally made of permanent magnet. The rotating sleeve 52 is sleeved on the pump shaft 30 and has a clearance fit with the pump shaft 30 to facilitate axial sliding relative to the pump shaft 30. The rotor section 51 is sleeved outside the rotating sleeve 52. The rotating sleeve 52 is located between the pump shaft 30 and the rotor section 51. In this embodiment, the rotating sleeve 52 is made of graphene, PPS reinforced with carbon fiber, or PEEK.

[0054] like Figure 2 As shown, a water-passing gap is formed between the rotor 50 and the heat dissipation wall 14, which connects the high-pressure area and the water passage 31. In this embodiment, the rotor 50 is fixedly connected to the impeller 40 so that the brushless motor can drive the impeller 40 to rotate around the pump shaft 30 within the impeller cavity 01. In this embodiment, the entire assembly formed by the rotor 50 and the impeller 40 is allowed to slide axially relative to the pump shaft 30, and is also allowed to rotate around the rotation axis relative to the pump shaft 30. In this embodiment, the connecting member 20 is located above the rotating sleeve 52, and the limiting wall 211 is used to limit the upward movement of the entire assembly formed by the rotor 50 and the impeller 40. Specifically, when the impeller 40 rotates, the impeller 40 will drive the rotor 50 to move upward together until the rotating sleeve 52 directly abuts against the limiting wall 211 of the connecting member 20.

[0055] like Figure 2 As shown, the electronic control board 70 is installed inside the electronic control cavity 03 and electrically connected to the stator 60 to control the stator 60, enabling the brushless motor to start, stop, and adjust its speed. In this embodiment, the electronic control board 70 is attached to the heat-conducting wall 15 via thermally conductive silicone. As is well known to those skilled in the art, the electronic control board 70 is also connected to external terminals via leads penetrating the lower housing 13 to obtain power and control signals from the outside.

[0056] like Figure 2 As shown, the lower limit member 80 is a retaining ring, and it is fixedly connected to the second end of the pump shaft 30. In this embodiment, the lower limit member 80 is press-fitted to the second end of the pump shaft 30. The lower limit member 80 is used to limit the downward movement of the entire assembly formed by the rotor 50 and the impeller 40. In this embodiment, the lower limit member 80 is annular, and the ratio of its axial length to its outer diameter is between 0.25 and 0.85. For example, the ratio of the axial length to the outer diameter of the lower limit member 80 is 0.3.

[0057] In this embodiment, the electric water pump will generate a main water flow and an internal circulating cooling water flow during operation. The main water flow is consistent with the prior art. As described above, during the rotation of the impeller 40, a high-pressure zone is formed between the impeller 40 and the cavity wall of the impeller cavity 01. The high-pressure zone is connected to the low-pressure zone near the inlet 04 through the rotor cavity 02 and the water passage 31. The water flows from the high-pressure zone through the water passage gap, the rotor cavity 02, and the water passage 31 to the low-pressure zone and merges with the main water flow. The low-pressure zone is located near the inlet 04, thereby forming an internal circulating cooling water flow. However, the internal circulating cooling water flow exchanges liquid with the main water flow. As described above, since the stator 60 is surrounded outside the rotor cavity 02, and the stator 60 is generally adjacent to or against the heat dissipation wall 14, the water flow passing through the water passage gap can carry away the heat generated by the stator 60 during the operation of the electric water pump. As described above, the heat generated by the electronic control board 70 during operation can be transferred to the heat-conducting wall 15, and the heat can be carried away by the water flow that is about to enter the second end of the pump shaft 30.

[0058] In general, during the assembly of an electric water pump, the stator 60 and the middle housing 12 are integrally molded using insert injection molding. The rotor 50 is placed inside the middle housing 12, and then the upper housing 11 is watertightly fixed to the middle housing 12. However, during the assembly of the control board 70, it is inserted from the opening on the side of the middle housing 12 away from the upper housing 11, and the lower housing 13 is then watertightly fixed to the middle housing 12. This means that the orientation of the housing 10 needs to be adjusted during assembly, causing inconvenience to on-site personnel. In this embodiment, to improve this problem, such as... Figure 2-3 As shown, bolt holes 111 with openings facing the lower housing 13 are provided on the upper housing 11 for bolt fixing, and through holes 121 corresponding to the bolt holes 111 are provided on the middle housing 12. Therefore, during installation, the insertion direction of the control board 70 is consistent with the insertion direction of the bolts, which facilitates installation. In this embodiment, for ease of installation, an annular groove 122 is provided on the opening side of the middle housing 12 near the lower housing 13. The lower housing 13 is provided with an insertion part 131 that can be inserted into the annular groove 122 and an abutment wall 132 that abuts against the end of the groove wall of the annular groove 122. The insertion part 131 and the annular groove 122 can be welded together by friction welding. Compared with welding using sealing rings and screws, this not only reduces the number of parts but also reduces the outer diameter of the lower housing 13. Compared with laser welding, friction welding does not require the lower housing 13 to be transparent and does not produce spatter. Compared with ultrasonic welding, friction welding does not require high-frequency vibration and is less destructive to the product.

[0059] In this embodiment, since the second end of the pump shaft 30 is located in the rotor cavity 02 and suspended above the heat-conducting wall 15, the rotation of the rotor 50 and impeller 40 is not easily transmitted to the heat-conducting wall 15 through the pump shaft 30, and the heat-conducting wall 15 is not prone to cracking. In the prior art, to avoid cracking of the heat-conducting wall 15, it is often made thicker, and a limiting structure that mates with the second end of the pump shaft 30 is often protruding on the heat-conducting wall 15. Thus, after the control board 70 is attached to the heat-conducting plate, due to the thickness of the heat-conducting wall 15, the heat of the control board 70 cannot be well transferred to the side of the heat-conducting wall 15 located in the rotor cavity 02. Furthermore, since the limiting structure protruding on the heat-conducting wall 15 occupies the space in the rotor cavity 02 and is often located in the center of the heat-conducting wall 15, the coolant in the rotor cavity 02 can only flow around the limiting structure, thus hindering the cooling of the rotor cavity 02. The liquid can only carry away the heat from the part of the control board 70 that is offset from the limiting structure. Therefore, the heat of the control board 70 cannot be effectively carried away by the water cooling in the rotor cavity 02, and it is mainly dissipated through natural cooling. The heat dissipation efficiency of the control board 70 is low. In this technical solution, the heat-conducting wall 15 is not prone to cracking. The minimum thickness of the heat-conducting wall 15 is 0.4mm, and the heat transfer rate of the heat-conducting wall 15 is faster. Moreover, there is no superfluous structure between the heat-conducting wall 15 and the second end of the pump shaft 30. The coolant in the rotor cavity 02 can flow through the entire surface of the heat-conducting wall 15 located in the rotor cavity 02, so that the heat of the control board 70 can be carried away by the liquid cooling in the rotor cavity 02 more quickly. The heat dissipation efficiency of the control board 70 is high. In addition, the absence of superfluous structure on the heat-conducting wall 15 can also prevent the vibration of the rotor 50 during operation from being conducted to the water jacket, thus preventing NVH problems. Therefore, this technical solution not only avoids the cracking of the heat-conducting wall 15, but also improves the heat dissipation efficiency of the control board 70.

[0060] In this embodiment, the thickness of the heat-conducting wall 15 is between 0.4mm and 1.5mm, which further ensures the strength of the heat-conducting wall 15 and the heat dissipation efficiency of the electronic control board 70.

[0061] In this embodiment, since the connecting member 20 is supported by a rigid wear-resistant material, it has high strength, corrosion resistance, high hardness and lubricity, and is not easily worn. Furthermore, the connecting member 20 is fixedly connected to the cavity wall of the impeller cavity 01, so the structure of the connecting member 20 is stable. The connecting member 20 is provided with a connecting body 21 sleeved on the first end of the pump shaft 30. The connecting body 21 is provided with a limiting wall 211 that directly abuts against the upper end of the rotating sleeve 52. The limiting wall 211 is used to limit the upward movement of the rotating sleeve 52, and the projection of the limiting wall 211 on the projection plane perpendicular to the pump shaft 30 covers... The projection of the rotating sleeve 52 and the projection of its outer contour are located outside the projection of the rotating sleeve 52, which has the following advantages. First, the integrated limiting wall 211 made of rigid wear-resistant material can directly replace the traditional gasket, eliminating the design of the gasket at the upper end of the rotating sleeve 52. This avoids the risk of missing, over-installing, or misaligned gaskets, and also prevents the gasket from falling off and getting stuck between the rotating sleeve 52 and the pump shaft 30, between the upper housing 11 and the impeller 40, or between the stator 60 and the rotor 50, causing the rotor 50 to jam and fail to rotate. Second, the high wear-resistant material ensures that there will be no loose fragments during long-term operation. Thirdly, this also means that the ring width of the limiting wall 211 is greater than the ring width of the rotating sleeve 52. When the ring width of the limiting wall 211 is the same as the ring width of the rotating sleeve 52, due to the deviation between the axis of the rotating sleeve 52 and the axis of the connecting body 21 after assembly, during the rotation of the rotor 50, and because the material of the rotating sleeve 52 is generally not wear-resistant, the upper end of the rotating sleeve 52 is easily worn and the wear is uneven, such as forming a dent. When the worn part gets stuck between the rotating sleeve 52 and the pump shaft 30, between the upper housing 11 and the impeller 40, or between the rotor 50 and the stator 60, it is easy to... This causes the rotor 50 to jam and fail to rotate. In this embodiment, the ring width of the limiting wall 211 is greater than the ring width of the rotating sleeve 52, and the projection of the limiting wall 211 covers the projection of the rotating sleeve 52, so that the upper end of the rotating sleeve 52 can be worn evenly. When it is worn evenly, the upper part of the rotating sleeve 52 falls off in the form of powder and enters the rotor cavity 02, and is carried away by the coolant in the rotor cavity 02. It is not easy to get stuck between the rotating sleeve 52 and the pump shaft 30, between the upper housing 11 and the impeller 40, or between the stator 60 and the rotor 50, causing the rotor 50 to jam and fail to rotate.

[0062] The rotating sleeve 52 is adapted to slide axially relative to the pump shaft 30, making it easier to assemble the rotor 50 and impeller 40 as a whole onto the pump shaft 30. The limiting wall 211 limits the upward movement of the rotor 50 and impeller 40 as a whole, allowing the connecting piece 20 to have more functions besides connecting the pump shaft 30, and simplifying its structure. At the same time, because the limiting wall 211 limits the upward movement of the rotor 50 and impeller 40 as a whole, the fixed position of the pump shaft 30 and the housing 10 is closer to the upper part of the rotor 50, which is beneficial for suppressing the deflection of the pump shaft 30. The lower limiting piece 80 limits the downward movement of the rotor 50 and impeller 40 as a whole, preventing the rotor 50 and impeller 40 from hitting the connecting piece 20 due to excessive upward travel during rotation, which is beneficial for reducing noise and increasing service life, and also solves the problem that the rotor 50, which moves freely along the pump shaft 30 during assembly, may be magnetically attracted away.

[0063] Furthermore, the first end of the pump shaft 30 is fixed to the cavity wall of the impeller cavity 01 via the connector 20. Therefore, when the impeller 40 rotates, the pump shaft 30 is fixed to the housing 10 very close to the upper part of the rotor 50. Compared with the prior art where the pump shaft 30 is fixed to the housing 10 in the rotor cavity 02, the deflection of the pump shaft 30 caused by the centroid offset of the rotor 50 and impeller 40 during the operation of the electric water pump is smaller, the vibration amplitude of the pump shaft 30 caused by the deflection of the pump shaft 30 is smaller, and the noise during the operation of the electric water pump is lower than that of the prior art. In addition, the machining accuracy of the connector 20 is easier to ensure than that of the upper housing 11, and the offset between the axis of the pump shaft 30 and the central axis of the impeller cavity 01 is smaller.

[0064] In this embodiment, the connecting body 21, which is fixed to the pump shaft 30, is connected to the upper housing 11 via connecting ribs 22. The connecting ribs 22 are distributed circumferentially, and the spacing between them allows water to flow smoothly from the inlet 04 into the impeller 40. The circumferential distribution of the connecting ribs 22 also ensures the positional accuracy of the connecting body 21 within the impeller cavity 01, minimizing the offset between the axis of the pump shaft 30 connected to the connecting body 21 and the central axis of the impeller cavity 01, thus effectively improving the operating efficiency of the electric water pump. The connecting body 21 is generally bullet-shaped, facing the inlet 04, with its upper surface roughly conical or dome-shaped. This shape helps reduce the flow resistance of water flowing from the inlet 04 to the impeller 40, improving the operating efficiency of the electric water pump. Compared to a scheme where the connecting body 21 and the first end of the pump shaft 30 are fitted together to form a bullet shape facing the inlet 04, there is no need to consider the matching of the two components during processing, resulting in lower processing precision requirements and lower overall cost.

[0065] In this embodiment, the ratio of the axial length to the outer diameter of the lower connecting part 214 is between 0.25 and 0.85. The lower connecting part 214 has a relatively long axial length, which on the one hand improves the strength of the lower connecting part 214, and on the other hand ensures that even if the lower connecting part 214 is worn, the limiting wall 211 can still limit the upward movement of the rotating sleeve 52, thus ensuring the normal operation of the electric water pump and extending the service life of the electric water pump.

[0066] In this embodiment, the connecting body 21 is a cylindrical shape with the opening facing downward. The first end of the pump shaft 30 is inserted into the cylinder of the connecting body 21 and abuts against the bottom of the cylinder. This is beneficial for the initial positioning of the first end of the pump shaft 30 during the assembly of the electric water pump and for the assembly of the lower limiting member 80 at the second end of the pump shaft 30.

[0067] In this embodiment, the inner diameter of the through hole 212 is larger than the inner diameter of the water passage 31. Compared with the inner diameter of the through hole 212 being the same as the inner diameter of the water passage 31, it is beneficial to avoid the assembly difficulties caused by the inconsistency between the axis of the through hole 212 and the axis of the water passage 31 when positioning the connector 21 and the pump shaft 30 by means of positioning pins and other components, thereby improving assembly efficiency.

[0068] In this embodiment, the cylinder of the connecting body 21 radially limits the first end of the pump shaft 30, and the upper and lower ends of the cylinder form a radial gap with the first end of the pump shaft 30. This facilitates the insertion of the first end of the pump shaft 30 into the connecting body 21 and its radial limiting engagement with the connecting body 21, further reducing assembly resistance and improving assembly efficiency.

[0069] In this embodiment, the roughness of the limiting wall 211 does not exceed Ra0.2, which helps to reduce the resistance when the rotating sleeve 52 rotates, avoid wear between the rotating sleeve 52 and the limiting wall 211, and extend the service life.

[0070] In this embodiment, the lower limit member 80 and the second end of the pump shaft 30 are press-fitted together. Compared with the prior art, which generally uses a snap ring to form the lower limit member 80, the lower limit member 80 is less likely to fall off, thus preventing the connector 20 from being frequently damaged by impact. The ratio of the axial length of the lower limit member 80 to its outer diameter is between 0.25 and 0.85. The axial length of the lower limit member 80 is longer than that of ordinary washers, making it more wear-resistant.

[0071] In this embodiment, when the upper housing 11 is made of plastic, the connector 20 and the upper housing 11 insert are integrally injection molded, which reduces costs and better ensures the positional accuracy of the connector 20 in the impeller cavity 01. This makes the deviation between the axis of the pump shaft 30 connected to the connector 21 and the central axis of the impeller cavity 01 smaller, which is beneficial to improving the operating efficiency of the electric water pump. When both the upper housing 11 and the connector 20 are made of metal, the connector 20 is welded to the upper housing 11. This not only ensures the positional accuracy of the connector 20 in the impeller cavity 01, but also the metal upper housing 11 has higher strength, which is more conducive to preventing the vibration of the impeller 40 and the rotor 50 from being transmitted to the upper housing 11 through the pump shaft 30, thus preventing the upper housing 11 from cracking.

[0072] In this embodiment, the pump shaft 30 is provided with a water passage 31 along its extension direction. The high-pressure area is connected to the low-pressure area through the rotor cavity 02 and the water passage 31, which can establish an internal circulation cooling channel inside the electric water pump. Water flows from the high-pressure area to the low-pressure area through the internal circulation cooling channel to form an internal circulation cooling water flow, which is beneficial for the heat dissipation of the stator 60 and the electronic control board 70. It should be understood that although the internal circulation cooling water flow may reduce the operating efficiency of the electric water pump, effective heat dissipation can improve the service life of the electric water pump. A water passage gap is formed between the heat dissipation wall 14 and the rotor 50. The internal circulation cooling water flows through the water passage gap, making it easier to carry away the heat generated by the stator 60 during the operation of the electric water pump, further improving the heat dissipation efficiency of the electric water pump.

[0073] The foregoing description of the specifications and embodiments is intended to explain the scope of protection of this utility model, but does not constitute a limitation on the scope of protection of this utility model. Modifications, equivalent substitutions, or other improvements to the embodiments of this utility model or a portion thereof that can be obtained by those skilled in the art through logical analysis, reasoning, or limited experimentation, based on the teachings of this utility model or the foregoing embodiments, should all be included within the scope of protection of this utility model.

Claims

1. An electric water pump, comprising an impeller chamber (01), a rotor chamber (02), an electrical control chamber (03), an inlet (04), and an outlet (05), including a pump shaft (30), an impeller (40), and a rotor (50), wherein the inlet (04) and the outlet (05) are connected to the impeller chamber (01), a first end of the pump shaft (30) is located in the impeller chamber (01), and a second end is located in the rotor chamber (02); the impeller (40) is located in the impeller chamber (01) and fixedly connected to the rotor (50); the rotor (50) is located in the rotor chamber (02) and includes a rotating sleeve (52), the rotating sleeve (52) being sleeved on the pump shaft (30) and clearance-fitted with the pump shaft (30) to be suitable for axial sliding relative to the pump shaft (30), characterized in that, it further comprises include: The connector (20) is made of rigid wear-resistant material. It is fixed to the cavity wall of the impeller cavity (01) and has a connector (21) sleeved on the first end of the pump shaft (30). The connector (21) is fixed to the pump shaft (30) and has a limiting wall (211) that directly abuts against the upper end of the rotating sleeve (52). The limiting wall (211) is used to limit the upward movement of the rotating sleeve (52). The projection of the limiting wall (211) on the projection plane perpendicular to the pump shaft (30) covers the projection of the rotating sleeve (52) and the outer contour projection is located outside the projection of the rotating sleeve (52). and The lower limit member (80) is fixed to the second end of the pump shaft (30) to limit the downward movement of the rotating sleeve (52).

2. The electric water pump as described in claim 1, characterized in that, The connector (20) is provided with at least two connecting ribs (22), and the connector (21) is generally in the shape of a bullet facing the inlet (04); one end of the connecting rib (22) is fixed to the connector (21), and the other end is fixed to the cavity wall of the impeller cavity (01), and each connecting rib (22) is arranged circumferentially; the lower end face of the connector (21) forms the limiting wall (211).

3. An electric water pump as described in claim 2, characterized in that, The connector (21) is provided with an upper connecting part (213) and a lower connecting part (214) that are connected as one piece. The upper connecting part (213) is fixedly connected to the connecting rib (22), and the ratio of the axial length to the outer diameter of the lower connecting part (214) is between 0.25 and 0.

85.

4. An electric water pump as described in claim 1, characterized in that, The connector (21) is a cylindrical shape with the opening facing downwards. The first end of the pump shaft (30) is inserted into the cylinder formed by the connector (21) and abuts against the bottom of the cylinder.

5. An electric water pump as described in claim 4, characterized in that, The pump shaft (30) is provided with a water passage (31) along its extension direction; the bottom of the connecting body (21) is provided with a through hole (212), the inner diameter of the through hole (212) being larger than the inner diameter of the water passage (31).

6. An electric water pump as described in claim 4, characterized in that, The cylinder formed by the connecting body (21) radially limits the first end of the pump shaft (30), and the upper and lower ends of the cylinder form a radial gap with the first end of the pump shaft (30).

7. An electric water pump as described in claim 1, characterized in that, The roughness of the limiting wall (211) does not exceed Ra0.

2.

8. An electric water pump as described in claim 1, characterized in that, The lower limit member (80) is annular and is press-fitted to the second end of the pump shaft (30). Its axial length to its outer diameter ratio is between 0.25 and 0.

85.

9. An electric water pump as described in any one of claims 1-8, characterized in that, It also includes a housing (10); the housing (10) includes an upper housing (11), a middle housing (12) and a lower housing (13), the upper housing (11) is watertightly fixed to the middle housing (12), the lower housing (13) is fixedly fixed to the middle housing (12), the impeller cavity (01) is formed in the upper housing (11), the rotor cavity (02) is formed in the middle housing (12), the middle housing (12) and the lower housing (13) enclose the electrical control cavity (03) which is watertightly isolated from the rotor cavity (02); the upper housing (11) is made of plastic material, and the connector (20) is integrally injection molded with the upper housing (11); or the upper housing (11) and the connector (20) are both made of metal material, and the connector (20) is welded to the upper housing (11).

10. An electric water pump as described in claim 9, characterized in that, It also includes a stator (60) and an electrical control board (70); the stator (60) is fixedly connected to the middle housing (12) and surrounds the rotor cavity (02); the electrical control board (70) is installed in the electrical control cavity (03) and electrically connected to the stator (60) to control the stator (60); the pump shaft (30) is provided with a water passage (31) along its extension direction; A high-pressure zone is formed between the impeller (40) and the cavity wall of the impeller cavity (01). The high-pressure zone is connected to a low-pressure zone near the inlet (04) through the rotor cavity (02) and the water passage (31). A heat dissipation wall (14) is formed on the side cavity wall of the rotor cavity (02). A water passage gap is formed between the heat dissipation wall (14) and the rotor (50). The water passage gap is used to connect the high-pressure zone and the water passage (31).

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