An electric pump

Abstract

The application discloses an electric pump, which comprises a shell, a stator assembly and a rotating assembly. The shell has a first inner cavity, and the stator assembly is fixedly arranged in the first inner cavity. The first inner cavity has a heat dissipation channel and a rotating assembly inner cavity for accommodating the rotating assembly. The rotating assembly is rotatably arranged in the rotating assembly inner cavity. The rotating assembly inner cavity comprises a liquid outlet channel extending along the circumference thereof. The liquid outlet channel is in communication with the liquid inlet and the liquid outlet of the heat dissipation channel. At least part of the heat dissipation channel is arranged on the radial side of the stator assembly along the radial direction of the electric pump. The liquid outlet channel comprises a contraction section and two intermediate sections. The two intermediate sections are respectively connected to the two ends of the contraction section. Compared with the liquid inlet, the contraction section is closer to the liquid outlet and is located between the liquid inlet and the liquid outlet. The minimum cross-sectional area of the contraction section is smaller than that of the intermediate sections. In this way, the heat exchange of the stator assembly is facilitated.

Description

Technical Field

[0001] This application relates to the field of fluid control, specifically to an electric pump suitable for scenarios such as refrigeration systems, air conditioning systems, and thermal management systems. Background Technology

[0002] Electric pumps, as core power equipment in the field of fluid transportation, are often used in thermal management systems. An electric pump includes a stator assembly, which in turn includes stator windings. During operation, the stator windings generate heat, causing the motor assembly and electrical components to overheat. Excessively high ambient temperatures affect the long-term reliable operation of the electric pump, impacting its performance and lifespan. Therefore, how to effectively dissipate heat from electric pumps is a technical problem that those skilled in the art need to consider. Summary of the Invention

[0003] Therefore, it is necessary to provide an electric pump for effective heat dissipation of a stator assembly, which addresses the above-mentioned problems. The pump includes a housing, a stator assembly, and a rotating assembly. The housing has a first inner cavity, and the stator assembly is fixedly disposed within the first inner cavity. The first inner cavity has a heat dissipation channel and a rotating assembly inner cavity for accommodating the rotating assembly. The rotating assembly is rotatably disposed within the rotating assembly inner cavity. The rotating assembly inner cavity includes a liquid outlet channel extending circumferentially therein. The liquid outlet channel communicates with the liquid inlet and outlet of the heat dissipation channel.

[0004] Along the radial direction of the electric pump, at least a portion of the heat dissipation channel is disposed on the radial side of the stator assembly; the liquid outlet channel includes a constriction section and two intermediate sections, the two intermediate sections being respectively connected to both ends of the constriction section; relative to the liquid inlet, the constriction section is closer to the liquid outlet and the constriction section is located between the liquid inlet and the liquid outlet; the minimum cross-sectional area of ​​the constriction section is smaller than the cross-sectional area of ​​the intermediate sections.

[0005] In this manner, the rotating assembly is rotatably disposed within the inner cavity of the rotating assembly; the inner cavity of the rotating assembly includes a liquid outlet channel extending circumferentially thereafter; the liquid outlet channel is connected to the liquid inlet and liquid outlet of the heat dissipation channel, thus, the rotation of the rotating assembly generates fluid flow pressure, forming a high-pressure zone and a low-pressure zone in the liquid outlet channel; the liquid inlet of the heat dissipation channel is connected to the high-pressure zone, and the liquid outlet is connected to the low-pressure zone, using the pressure difference to drive the coolant circulation; furthermore, along the radial direction of the electric pump, at least a portion of the heat dissipation channel is disposed on the radial side of the stator assembly; the liquid outlet channel includes a constriction section and an intermediate section, the constriction section being closer to the liquid outlet than the liquid inlet and the constriction section being located within the... Between the inlet and the outlet, the minimum cross-sectional area of ​​the contraction section is smaller than the cross-sectional area of ​​the middle section connected to both ends of the contraction section in the circumferential direction. By setting an outlet channel with a contraction section, the change in the cross-sectional area of ​​the outlet channel forms a dynamic pressure gradient. When the medium flows through the contraction section, the increased flow velocity leads to a decrease in local static pressure. A relatively low-pressure zone is formed in the area after the minimum cross-section of the contraction section, which is opposite to the pressure of the heat dissipation channel. The pressure difference between the heat dissipation channel and the area after the minimum cross-section of the contraction section generates a directional suction force on the medium in the heat dissipation channel, causing the working medium to flow faster than in other locations. This allows the heat dissipation channel to remove more heat from the stator winding in a certain period of time, which is beneficial for heat dissipation of the stator winding. Attached Figure Description

[0006] Figure 1 This is a three-dimensional structural schematic diagram of an electric pump according to one embodiment of the present application;

[0007] Figure 2 yes Figure 1 Schematic diagram of the structure of the electric pump along section AA;

[0008] Figure 3 yes Figure 2 A partial schematic diagram of point K;

[0009] Figure 4 yes Figure 2 Schematic diagram of the structure of the electric pump along the BB section;

[0010] Figure 5 yes Figure 2 Schematic diagram of the structure of the electric pump along the CC section;

[0011] Figure 6 This is a schematic diagram of a portion of the liquid outlet channel in another embodiment provided in this application;

[0012] Figure 7 This is a schematic diagram of the structure of an electric pump according to another embodiment of the present application;

[0013] Figure 8This is a schematic diagram of the structure of an electric pump according to another embodiment of the present application;

[0014] Figure 9 yes Figure 2 Exploded cross-sectional view of the electric pump.

[0015] Figure label:

[0016] Electric pump 1, housing 11, inlet 112, outlet 113, first inner cavity 101, stator assembly 12, rotating assembly 13, rotating assembly inner cavity 13a, liquid outlet channel 131, contraction section 1311, throat 1311a, inlet end 1311b, outlet end 1311c, expansion section 1312, starting end 1312a, ending end 1312b, variable diameter section 13121, stabilizing section 13122, intermediate section 1313, first protrusion 118, second protrusion 119, rotor assembly 14, rotating... 141, rotor cavity 142, impeller assembly 15, impeller cavity 152, heat dissipation channel 16, liquid inlet 161, liquid outlet 162, inlet channel 163, return channel 164, connecting cavity 1011, electrical control unit 17, shaft 18, first groove 191, pump cover 111, thermal pad 20, second housing 21, second inner cavity 102, stator housing 1211, upper end 1211a, stator winding 1212, first plane L, circumference C, projection of heat dissipation channel 16', projection of stator winding 12'. Detailed Implementation

[0017] The specific embodiments of this application are further described in detail below with reference to the accompanying drawings.

[0018] First, it should be noted that the directional terms such as up, down, left, right, front, back, inner, outer, top, and bottom mentioned or possibly mentioned in this invention specification are defined relative to the structures shown in the corresponding drawings. They are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0019] See Figures 1 to 9As shown, the present application provides an electric pump 1, comprising a housing 11, a stator assembly 12, and a rotating assembly 13. The housing 11 is provided with an inlet 112 and an outlet 113, both the inlet 112 and the outlet 113 are in communication with a liquid outlet channel 131. The housing 11 has a first inner cavity 101 and a wall portion corresponding to the first inner cavity 101, and the stator assembly 12 is fixedly arranged in the first inner cavity 101. The first inner cavity 101 is provided with a heat dissipation channel 16 and a rotating assembly inner cavity 13a for accommodating the rotating assembly 13, the rotating assembly 13 is rotatably arranged in the rotating assembly inner cavity 13a, the rotating assembly inner cavity comprises the liquid outlet channel 131 extending along the circumferential direction thereof, and both ends of the liquid outlet channel 131 are respectively in communication with a liquid inlet 161 and a liquid outlet 162 of the heat dissipation channel 16.

[0020] The liquid outlet channel 131 comprises a contraction section 1311 and a middle section 1313. Compared with the liquid inlet 161, the contraction section 1311 is closer to the liquid outlet 162, and the contraction section 1311 is located between the liquid inlet 161 and the liquid outlet 162. The minimum cross-sectional area of the contraction section 1311 is smaller than the cross-sectional area of the middle section 1313 respectively communicated with two circumferential ends of the contraction section 1311. Along the radial direction of the electric pump 1, at least part of the heat dissipation channel 16 is arranged on one radial side of the stator assembly 12.

[0021] With this arrangement, the electric pump 1 is provided with the liquid outlet channel 131 having the contraction section 1311, and a pressure gradient is formed through the change of cross-sectional area. When a working medium flows through the contraction section 1311, the increase of flow velocity leads to a decrease of local static pressure, and a relatively low-pressure area is formed in a region behind the minimum cross-section of the contraction section 1311, which forms a pressure difference with the pressure of the working medium in the heat dissipation channel 16. The pressure difference generates a directional suction force on the medium in the heat dissipation channel 16, prompting the flow velocity of the working medium to be faster than that at other positions, further enabling the heat dissipation channel 16 to take away more heat of the stator assembly 12 within a certain period of time, which is beneficial to heat dissipation of the stator assembly 12.

[0022] It should be noted that the pressure value of the working medium at the liquid inlet 161 is greater than the pressure value of the working medium at the liquid outlet 162. Here and hereinafter, the axial direction of the electric pump 1 refers to the extending direction of the shaft of the electric pump 1, the radial direction of the electric pump 1 refers to a direction perpendicular to the axial direction of the electric pump 1, and the circumferential direction of the electric pump 1 refers to a direction surrounding the shaft of the electric pump 1.

[0023] It should be noted that the cross-sectional area of the contraction section 1311 is a cross-sectional area perpendicular to the flow direction. On the flow path of the working medium, a plane perpendicular to the flow direction is taken, and the region of the contraction section 1311 on this plane is intercepted to obtain the cross-sectional area, reference may be made to Figure 6 1311a in.

[0024] Furthermore, the inlet 112 and outlet 113 of the housing 11 are both connected to the liquid outlet channel 131. Compared to the inlet 112, the liquid inlet 161 is closer to the outlet 113. The heat dissipation channel 16 includes a return channel 164 with a liquid outlet 162. The cross-sectional area of ​​the contraction section 1311 is smaller than the cross-sectional area of ​​the return channel 164. Thus, compared to the pressure inside the return channel 164, the pressure in the area after the minimum cross-section of the contraction section 1311 is smaller. This pressure difference can generate a directional suction force on the medium inside the return channel 164, causing the working medium to flow faster than in other locations. This further enables the heat dissipation channel 16 to remove more heat from the stator assembly 12 within a certain period of time, which is beneficial for heat dissipation of the stator assembly 12.

[0025] Regarding the formation of contraction segment 1311, refer to Figure 1 , Figure 4 , Figure 5 In one specific embodiment, the housing 11 includes a pump cover 111 and a second housing 21. The second housing 21 and the pump cover 111 are correspondingly arranged along the axial direction of the electric pump 1 and are fixedly connected or limitedly connected. The second housing 21 has a first protrusion 118 protruding toward the pump cover 111. There is a gap between the first protrusion 118 and the rotating assembly 13 and the pump cover 111, at least a portion of which is a contraction section 1311. In another specific embodiment, refer to... Figures 2 to 5 The housing 11 includes a pump cover 111 and a second housing 21. The second housing 21 and the pump cover 111 are arranged correspondingly along the axial direction of the electric pump 1 and are fixedly connected or limitedly connected. The pump cover 111 has a second protrusion 119 protruding towards the second housing 21. There is a gap between the second protrusion 119 and the rotating assembly 13 and the pump cover 111. At least part of the gap is a contraction section 1311. Of course, in order to ensure that the gap is evenly distributed in the circumferential direction, the curvature of the arc surface of the first protrusion 118 and the second protrusion 119 can match the outer contour of the rotating assembly 13.

[0026] Of course, as another implementation, the electric pump 1 may not include the pump cover 111, and the pump cover 111 may be integrated into the external structure of the electric pump 1. This arrangement is more conducive to the integrated design of the electric pump 1, making the structure of the electric pump 1 more compact, and is more conducive to the miniaturization and weight reduction of the electric pump 1 structure.

[0027] It is understandable that the first protrusion 118 and the second protrusion 119 can exist individually or simultaneously, as long as the protrusion is at least partially located within the outlet channel 131 before the inlet 161, such that the cross-sectional area of ​​the outlet channel 131 at the protrusion is smaller than the cross-sectional area of ​​the middle section 1313 connecting its two ends. This is the contraction section 1311. Of course, the first protrusion 118 and the second protrusion 119 can be one or more. When there are multiple outlets 161 arranged along the circumference of the electric pump 1, multiple protrusions can also be arranged accordingly to form multiple contraction sections 1311.

[0028] In one specific embodiment, the electric pump has an internal tube, the liquid outlet channel 131 includes the inner cavity of the internal tube, and the contraction section 1311 is located in the internal tube.

[0029] In one specific embodiment, the liquid outlet channel 131 has a built-in baffle, and the gap between the baffle and the rotating assembly 13 and the pump cover 111 is a contraction section 1311.

[0030] In one specific embodiment, the second housing 21 includes a stator housing 1211, and the pump cover 111 is sealed to the stator housing 1211 by welding. It is worth noting that the sealed connection here means that when the electric pump 1 is working, the working medium inside the electric pump 1 will not leak to the outside of the electric pump 1 through the joint surface between the pump cover 111 and the stator assembly 12. The stator assembly 12 is manufactured using an insert injection molding process and includes a stator core, a stator housing 1211, and a stator winding 1212. The heat dissipation channel 16 is disposed on one radial side of the stator winding 1212 to dissipate heat from the stator winding 1212 and further improve the heat dissipation efficiency.

[0031] In one specific embodiment, reference is made to Figure 5 The electric pump 1 also includes a shaft 18, which is at least partially located in the first inner cavity 101. The shaft 18 is connected to or integrally designed with the rotating assembly 13. The second inner cavity 102 is provided with at least a portion of the electronic control unit 17, which is electrically connected to the stator assembly 12. Alternatively, the electric pump 1 may not include the electronic control unit 17 and may be directly electrically connected to an external control module, which simplifies the structure of the electric pump 1. The second inner cavity 102 is independent of the first inner cavity 101, effectively isolating the heat dissipation areas of the electronic components and improving the reliability of the circuit components.

[0032] In one specific embodiment, the inner cavity 13a of the rotating assembly includes at least a rotor cavity 142 and an impeller cavity 152, which are connected. The first inner cavity 101 is capable of facilitating the flow of a working medium. The rotating assembly 13 includes a rotor assembly 14 and an impeller assembly 15 connected to the rotor 141. The rotor assembly 14 includes a rotor 141, which is rotatably disposed in the rotor cavity 142, with the stator assembly 12 located radially outside the rotor 141. The rotor 141 is located in the rotor cavity 142, and the impeller assembly 15 is located in the impeller cavity 152. The impeller assembly 15 can be driven to rotate by the rotor 141, and the magnetic field generated by the stator assembly 12 drives the impeller assembly 15 to rotate and transport liquid. The electric pump 1 can generate a magnetic field by energizing the stator assembly 12. The magnetic field drives the rotor 141 to rotate relative to the stator assembly 12, causing the rotor 141 to drive the impeller assembly 15 to rotate and draw liquid into the inlet 112. After flowing in the inner cavity of the housing 11, the liquid is pumped to the outlet 113. During this period, the electrical control unit 17 can control the rotation speed and operation of the rotor 141 through the stator assembly 12.

[0033] Further, refer to Figures 1 to 6 The rotating assembly cavity 13a also includes a liquid outlet channel 131 extending circumferentially along the electric pump 1. The constriction section 1311 includes a throat 1311a, which contains the minimum cross-section of the constriction section 1311. The cross-sectional area of ​​the intermediate section 1313 connected to the outlet end 1311c of the constriction section 1311 is 1.15-1.5 times the cross-sectional area of ​​the throat 1311a. The cross-sectional area of ​​the intermediate section 1313 connected to the inlet end 1311b of the constriction section 1311 is 2.2-2.6 times the cross-sectional area of ​​the throat 1311a.

[0034] In some specific embodiments, the liquid outlet channel 131 includes a contraction section 1311, an expansion section 1312, and an intermediate section 1313. The expansion section 1312 is connected to the outlet end 1311c of the contraction section 1311, or the expansion section 1312 is connected to the liquid outlet 162. The ratio of the cross-sectional area of ​​the beginning end 1312a of the expansion section to the cross-sectional area of ​​the throat 1311a is 1:1.15-1:1.5, for example, 1:1.25. Further, the ratio of the cross-sectional area of ​​the end end 1312b of the expansion section to the cross-sectional area of ​​the throat 1311a is 1:2-3. The expansion section 1312 includes a stable sub-segment 13122 and a variable diameter sub-segment 13121 with an expansion angle. The maximum cross-sectional area of ​​the variable diameter sub-segment 13121 is less than or equal to the cross-sectional area of ​​the stable sub-segment 13122. The cross-sectional area of ​​the stabilizing section 13122 is not less than 0.8-1.2 times the cross-sectional area of ​​the outlet 113, and the expansion angle of the variable diameter section 13121 is 2-6° to achieve pressure recovery and smooth flow rate transition; or in another specific embodiment, the flow cross-sectional area of ​​the expansion section 1312 gradually increases from the inlet 161 along the circumference of the electric pump 1 to the outlet 162. With this setting, the sudden change in the cross-sectional area of ​​the contraction section 1311, utilizing the Venturi effect, increases the medium flow rate, and the decrease in static pressure at the throat 1311a causes a pressure difference between the return channel 164 and the outlet 162 (the low-pressure area after the minimum cross-section of the contraction section 1311). The pressure difference drives the working medium to circulate faster, further improving the heat dissipation efficiency of the stator assembly 12.

[0035] In one specific embodiment, at least one end of the shaft 18 is located within the rotor cavity 142, at least a portion of the rotating assembly 13 is sleeved on the outer periphery of the shaft 18, and a portion of the shaft 18 is fixed to the stator housing 1211. The rotating assembly 13 can rotate around the shaft 18. Of course, in other embodiments, the rotating assembly 13 and the shaft 18 are fixedly connected, and the shaft 18 rotates synchronously with the rotating assembly 13.

[0036] In one specific embodiment, reference is made to Figure 2 , Figure 5 Define a circle C, with the axis of the electric pump 1 as the center and the distance from the axis to the inlet end 1311b of the contraction section 1311 as the radius; the arc length of the contraction section 1311 is controlled to be 1 / 12 to 1 / 6 of the circle C; this setting is beneficial to control the length of the contraction section 1311, so as to reduce the impact on the overall flow of the liquid outlet channel 131 and ensure the normal operation of the electric pump 1.

[0037] In one specific embodiment, the heat dissipation channel 16 includes an inlet channel 163 and a return channel 164. The inlet channel has a liquid inlet 161, and the return channel 164 has a liquid outlet 162. Both the inlet channel 163 and the return channel 164 are connected to the bottom connecting cavity 1011. The centerline of at least one side wall of the connecting cavity 1011 is perpendicular to the axial direction of the electric pump 1, forming a three-dimensional heat dissipation circuit that penetrates the housing 11 and covers the circumferential and axial regions of the stator assembly 12. At least a portion of the wall corresponding to the heat dissipation channel 16 is the second housing 21. A portion of the heat dissipation channel 16 extends along the circumferential direction of the electric pump 1. The heat dissipation channel 16 is formed within the second housing 21. The heat dissipation channel 16 extends along the circumferential direction of the electric pump 1 but does not penetrate the second housing 21 circumferentially. Its liquid inlet 161 and liquid outlet 162 are both connected to the impeller cavity 152.

[0038] In one specific embodiment, the impeller cavity 152 includes a liquid outlet channel 131. The axial orthographic projection of the liquid inlet 161 is located in the high-pressure zone within the liquid outlet channel 131, and the axial orthographic projection of the liquid outlet 162 is located in the low-pressure zone within the liquid outlet channel 131. The cooling medium is circulated using the pressure difference. In another specific embodiment, the liquid outlet channel 131 is at least partially a volute flow channel, allowing the working medium to exit the electric pump 1 along the volute flow channel. Along the direction of the working medium's flow within the volute flow channel, the liquid inlet 161 is closer to the outlet of the volute flow channel than the liquid outlet 162. This arrangement helps to increase the pressure difference between the liquid inlet 1611 of the liquid inlet 161 and the liquid outlet 162 of the liquid outlet 162, thereby increasing the flow velocity of the working medium within the heat dissipation channel 16.

[0039] As one implementation, the heat dissipation channel 16 is arranged in a circle along the circumference of the electric pump 1. This increases the heat dissipation area of ​​the stator assembly 12, thereby improving the heat dissipation of the stator assembly 12.

[0040] In one specific embodiment, reference is made to Figure 9 The second housing 21 includes at least a portion of the stator housing 1211, which is injection molded with the stator winding 1212 as an insert. The stator assembly 12 also includes a first groove 191, which is formed in the stator housing 1211. The first groove 191 is recessed inward from the upper end 1211a of the stator housing 1211 along the axial direction of the electric pump 1. The wall portion corresponding to the heat dissipation channel 16 extending along the circumferential direction of the electric pump 1 includes at least the wall portion corresponding to the first groove 191. As another embodiment, the heat dissipation channel 16 is disposed radially outside the stator winding 1212 along the radial direction of the electric pump 1, ensuring that heat is directly conducted to the cooling medium. This arrangement, utilizing the structure of the stator assembly 12 to form the heat dissipation channel 16, helps to reduce the manufacturing difficulty of the electric pump 1.

[0041] In one specific embodiment, reference is made to Figure 5 A first plane L is defined parallel to the axis of the electric pump 1. The orthographic projection 16' of the heat dissipation channel 16 on the first plane L completely covers the orthographic projection area 12' of the stator winding 1212 on the first plane L, ensuring that the heat of the stator winding 1212 is fully conducted to the cooling medium through radiation and convection.

[0042] The medium pressurized by the impeller assembly 15 enters the heat dissipation channel 16 from the high-pressure area (near the outlet 113) of the impeller cavity 152 through the liquid inlet 161. The inlet channel 163 and the return channel 164 of the heat dissipation channel 16 are connected to the bottom connecting cavity 1011. Along the axial direction of the electric pump 1, the inlet channel 163 and the return channel 164 extend in the second housing 21 and extend in parallel directions. One end of the return channel 164 is connected to the outlet channel 131 and the other end is connected to the connecting cavity 1011. One end of the inlet channel 163 is connected to the outlet channel 131 and the other end is connected to the connecting cavity 1011, forming a three-dimensional heat dissipation circuit that runs through the housing 11. After flowing through the outer periphery of the stator winding 1212, it returns to the low-pressure area through the liquid outlet 162, forming a self-driven cycle. The increased flow rate at the throat 1311a of the contraction section 1311 generates a local low pressure in the outlet channel 131, which in turn creates suction on the medium in the return channel 164 of the heat dissipation channel 16, thereby increasing the circulation flow rate and the working medium velocity, and further improving the heat dissipation efficiency.

[0043] In this embodiment, the heat dissipation process is roughly as follows: the working medium enters the impeller cavity 152 from the inlet 112. After being pressurized by the impeller assembly 15, the working medium is divided into two paths: the main path medium flows through the liquid outlet channel 131, passing through the contraction section 1311 and the expansion section 1312 to the outlet 113; the branch enters the heat dissipation channel 16 through the liquid inlet 161. The liquid in the heat dissipation channel 16 flows through the inlet channel 163, the connecting cavity 1011, and the return channel 164, and then returns to the liquid outlet channel 131 from the liquid outlet 162. As the working medium's flow rate increases after passing through the contraction section 1311, a low-pressure zone is generated in the middle section 1313 after the contraction section 1311. The low-pressure zone generates suction, which accelerates the extraction of the working medium in the return channel 164, thereby accelerating the circulation of the working medium in the heat dissipation channel 16. Finally, the flow rate is restored after passing through the expansion section 1312, and the heat is discharged through a dual-path heat exchange via the shell 11 or the flow of the working medium.

[0044] To further improve the heat dissipation range, it is linked with the heat dissipation of the electronic control unit 17, referencing... Figure 5 The electronic control unit 17 contacts the wall of the second inner cavity 102 through the thermal pad 20. The heat dissipation channel 16 completely covers the orthogonal projection of the electronic control unit 17 on the first plane L, realizing dual heat dissipation through heat conduction of the housing 11 and heat exchange of the working medium.

[0045] It should be noted that the above embodiments are only used to illustrate this application and are not intended to limit the technical solutions described in this application. Although this specification has described this application in detail with reference to the above embodiments, those skilled in the art should understand that those skilled in the art can still make modifications or equivalent substitutions to this application, and all technical solutions and improvements that do not depart from the spirit and scope of this application should be covered within the protection scope of this application.

Claims

1. An electric pump, characterized in that, The system includes a housing (11), a stator assembly (12), and a rotating assembly (13). The housing (11) has a first inner cavity (101), and the stator assembly (12) is fixedly disposed in the first inner cavity (101). The first inner cavity (101) has a heat dissipation channel (16) and a rotating assembly inner cavity (13a) for accommodating the rotating assembly (13). The rotating assembly (13) is rotatably disposed in the rotating assembly inner cavity (13a). The rotating assembly inner cavity (13a) includes a liquid outlet channel (131) extending circumferentially therein. The liquid outlet channel (131) communicates with the liquid inlet (161) and liquid outlet (162) of the heat dissipation channel (16). Along the radial direction of the electric pump, at least a portion of the heat dissipation channel (16) is disposed on the radial side of the stator assembly (12); the liquid outlet channel (131) includes a contraction section (1311) and two intermediate sections (1313), the two intermediate sections (1313) are respectively connected to both ends of the contraction section (1311), the contraction section (1311) is closer to the liquid outlet (162) than the liquid inlet (161) and the contraction section (1311) is located between the liquid inlet (161) and the liquid outlet (162), and the minimum cross-sectional area of ​​the contraction section (1311) is smaller than the cross-sectional area of ​​the intermediate section (1313).

2. The electric pump according to claim 1, characterized in that, The housing (11) has an inlet (112) and an outlet (113) that communicate with the outside. Both the inlet (112) and the outlet (113) are connected to the liquid outlet channel (131). Compared with the inlet (112), the liquid inlet (161) is closer to the outlet (113). The heat dissipation channel (16) includes a return channel (164) with the liquid outlet (162). The cross-sectional area of ​​the contraction section (1311) is smaller than the cross-sectional area of ​​the return channel (164).

3. The electric pump according to claim 1, characterized in that, The housing (11) includes a pump cover (111) and a second housing (21). The second housing (21) and the pump cover (111) are arranged correspondingly along the axial direction of the electric pump and are fixedly connected or limitedly connected. The stator assembly (12) includes a stator winding (1212) and a stator housing (1211). The pump cover (111) and the stator housing (1211) are welded and fixed or sealed. The stator winding (1212) is embedded in at least part of the second housing (21).

4. The electric pump according to claim 3, characterized in that, The second housing (21) has a first protrusion (118) protruding toward the pump cover (111), and / or the pump cover (111) has a second protrusion (119) protruding toward the second housing (21); the first protrusion (118) and / or the second protrusion (119) have a gap with the rotating assembly (13) and the pump cover (111), the gap being at least partially the contraction section (1311); Alternatively, the electric pump has an internal tube, the liquid outlet channel (131) includes the inner cavity of the internal tube, and the contraction section (1311) is located in the internal tube; Alternatively, the liquid outlet channel (131) may have a built-in baffle, and the gap between the baffle and the rotating assembly (13) and the pump cover (111) may be at least partially the contraction section (1311).

5. The electric pump according to claim 1, characterized in that, The liquid outlet channel (131) further includes an expansion section (1312), which includes a starting end (1312a) and an ending end (1312b). The cross-sectional area of ​​the expansion section (1312) is larger than the minimum cross-sectional area of ​​the contraction section (1311). The starting end (1312a) is connected to the outlet end (1311c) of the contraction section (1311), or the starting end (1312a) is connected to the liquid outlet (162).

6. The electric pump according to claim 5, characterized in that, The contraction section (1311) includes a throat (1311a), which contains the minimum cross-section of the contraction section (1311), and the area ratio of the cross-section of the end (1312b) of the expansion section to the cross-section of the throat (1311a) is 1:2-3; or, from the inlet (161) along the circumference of the electric pump to the outlet (162), the flow cross-sectional area of ​​the expansion section (1312) gradually increases; or, the expansion section (1312) includes a variable diameter sub-section (13121) and a stable sub-section (3122), the maximum cross-sectional area of ​​the variable diameter sub-section (13121) is less than or equal to the cross-sectional area of ​​the stable sub-section (13122), and the cross-sectional area of ​​the stable sub-section (13122) is not less than 0.8-1.2 times the cross-sectional area of ​​the intermediate section (1313).

7. The electric pump according to any one of claims 1 to 6, characterized in that, The inner cavity (13a) of the rotating assembly includes at least an impeller cavity (152) and a rotor cavity (142) arranged sequentially along the axial direction of the electric pump. The rotating assembly (13) includes a rotor assembly (14) and an impeller assembly (15). The rotor assembly (14) includes a rotor (141) rotatably disposed in the rotor cavity (142). The impeller assembly (15) is located in the impeller cavity (152). The stator assembly (12) is located radially outside the rotor (141). The impeller assembly (15) is connected to the rotor (141). The liquid outlet channel (131) is at least partially located in the impeller cavity (152). And / or, the electric pump further includes a shaft (18) at least partially located in the first inner cavity (101), the shaft being connected to or integrally designed with the rotating assembly (13); the heat dissipation channel (16) extends along the axial and circumferential directions of the electric pump respectively, the heat dissipation channel (16) includes an inlet channel (163) and a return channel (164), the inlet channel (163) having the liquid inlet (161), the return channel (164) having the liquid outlet (162), at least a partial connecting cavity (1011) between the inlet channel (163) and the return channel (164), the centerline of at least one side wall of the connecting cavity (1011) being perpendicular to the axial direction of the electric pump.

8. The electric pump according to claim 3 or 4, characterized in that, The stator assembly (12) includes a stator housing (1211) and a stator winding (1212). The second housing (21) includes at least a portion of the stator housing (1211). Along the axial direction of the electric pump, the stator housing (1211) is injection molded with the stator winding (1212) as an insert. The second housing (21) also includes a first groove (191). The first groove (191) is recessed inward from the upper end of the stator housing (1211) along the axial direction of the electric pump. The first groove (191) extends along the axial direction and the axial direction of the electric pump, respectively. And / or, define a first plane (L) parallel to the axis of the electric pump, wherein the orthographic projection of the heat dissipation channel (16) onto the first plane (L) at least partially covers the orthographic projection of the stator winding (1212) onto the first plane (L); And / or, the curvature of the first protrusion (118) and the second protrusion (119) matches the outer contour of the rotating component (13).

9. The electric pump according to any one of claims 1 to 6, characterized in that, The constriction section (1311) includes a throat (1311a), which comprises the minimum cross-section of the constriction section (1311). The cross-sectional area of ​​the intermediate section (1313) connected to the inlet end (1311b) of the constriction section (1311) is 2.2-2.6 times the cross-sectional area of ​​the throat (1311a). The cross-sectional area of ​​the intermediate section (1313) connected to the outlet end (1311c) of the constriction section (1311) is 1.15-1.5 times the cross-sectional area of ​​the throat (1311a). And / or, define a circumference (C) with the axis of the electric pump as the center and the distance from the axis to the inlet end (1311b) of the contraction section as the radius; the arc length of the contraction section (1311) is 1 / 12 to 1 / 6 of the circumference; And / or, the electric pump includes an electronic control unit (17), the housing (11) further has a second inner cavity (102) independent of the first inner cavity (101), the electronic control unit (17) is electrically connected to the stator assembly (12), and the electronic control unit (17) is located in the second inner cavity (102).

10. The electric pump according to claim 9, characterized in that, The electronic control unit (17) contacts the wall of the second inner cavity (102) through the heat-conducting pad (20), defining a first plane (L) parallel to the axis of the electric pump. The orthographic projection of the heat dissipation channel (16) on the first plane (L) completely covers the orthographic projection of the electronic control unit (17) on the first plane (L).

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