Patent Publication Number: US-11384776-B2

Title: Electric pump

Description:
RELATED APPLICATIONS 
     This application is the national phase of International Application No. PCT/CN2018/092349, titled “ELECTRIC PUMP”, filed on Jun. 22, 2018, which claims priority to Chinese Patent Application No. 201710731154.1, titled “ELECTRIC PUMP”, filed on Aug. 23, 2017 with the National Intellectual Property Administration, PRC. The entire contents of these applications are incorporated herein by reference in their entirety. 
     FIELD 
     The present application relates to a fluid pump, and in particular to an electric pump. 
     BACKGROUND 
     The automobile industry is developing rapidly. With the automobile performance developing toward safer, more reliable, more stable, fully automated, intelligent and environment-friendly and energy saving, electric pumps are widely used in vehicle thermal management systems, and can meet the market requirements. 
     The electric pump includes an electronic control unit, and the electronic control unit includes an electronic control board. For a high-power pump, the electronic control unit generates heat during working. If the heat is accumulated to a certain extent and cannot be dissipated in time, the performance of the electronic control board will be affected, thereby reducing the service life of the electric pump. 
     SUMMARY 
     An object of the present application is to provide an electric pump, which is beneficial to the heat dissipation of the electronic control board, thereby improving the service life of the electric pump. 
     In order to achieve the above object, the following technical solutions are provided according to the present application. 
     An electric pump includes a pump housing, a rotor assembly, a stator assembly and an electronic control board. The pump housing is provided with a pump inner chamber, and the pump inner chamber includes a first chamber and a second chamber. The rotor assembly is arranged in the first chamber, and the stator assembly and the electronic control board are arranged in the second chamber. The electric pump includes an isolation sleeve, and at least part of the isolation sleeve is arranged between the rotor assembly and the stator assembly. The first chamber is arranged on one side of the isolation sleeve, and the second chamber is arranged on another side of the isolation sleeve. The electric pump further includes a heat dissipation plate. The isolation sleeve includes a bottom portion, and at least part of the heat dissipation plate is arranged between the electronic control board and the bottom portion. At least part of the bottom portion is in direct contact with at least part of the heat dissipation plate, or silicone grease or silica gel is filled between the at least part of the bottom portion and the at least part of the heat dissipation plate, or heat conducting patches are provided between the at least part of the bottom portion and the at least part of the heat dissipation plate. Such arrangement is beneficial to the heat dissipation of the electronic control board, thereby prolonging the service life of the electric pump. 
     An electric pump includes a pump housing, a rotor assembly, a stator assembly and an electronic control board. The pump housing is provided with a pump inner chamber, and the pump inner chamber includes a first chamber and a second chamber. The rotor assembly is arranged in the first chamber, and the stator assembly and the electronic control board are arranged in the second chamber. The electric pump includes an isolation sleeve, and at least part of the isolation sleeve is arranged between the rotor assembly and the stator assembly. The electric pump further includes a heat dissipation plate. Part of the heat dissipation plate and the isolation sleeve form part of the first chamber, and at least part of the heat dissipation plate is arranged between the isolation sleeve and the electronic control board. Such arrangement is beneficial to the heat dissipation of the electronic control board, thereby prolonging the service life of the electric pump. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic sectional view of a first embodiment of an electric pump according to the present application; 
         FIG. 2  is schematic sectional view of a second embodiment of the electric pump according to the present application; 
         FIG. 3  is a schematic perspective view of a heat dissipation plate shown in  FIG. 1  or  FIG. 2 ; 
         FIG. 4  is a schematic sectional view of the heat dissipation plate shown in  FIG. 3 ; 
         FIG. 5  is a schematic perspective view of a first housing shown in  FIG. 1  or  FIG. 2 ; 
         FIG. 6  is a schematic perspective view of the electric pump without an electronic control board and a bottom cover shown in  FIG. 1  or  FIG. 2 ; 
         FIG. 7  is a schematic perspective view of a heat dissipation plate shown in  FIG. 1  or  FIG. 2 ; 
         FIG. 8  is a schematic sectional view of the electronic control board shown in  FIG. 7 ; 
         FIG. 9  is a schematic sectional view of a third embodiment of the electric pump according to the present application; 
         FIG. 10  is a schematic sectional view of a fourth embodiment of the electric pump according to the present application; 
         FIG. 11  is a schematic perspective view of the heat dissipation plate shown in  FIG. 9  or  FIG. 10 ; 
         FIG. 12  is a schematic sectional view of the electronic control board shown in  FIG. 11 ; 
         FIG. 13  is a schematic structural view of a first embodiment of an isolation sleeve shown in  FIG. 1 ,  FIG. 2 ,  FIG. 9  and  FIG. 10 ; 
         FIG. 14  is a schematic sectional view of the isolation sleeve shown in  FIG. 13 ; 
         FIG. 15  is a schematic perspective view of a pump shaft shown in  FIG. 1 ,  FIG. 2 ,  FIG. 9  and  FIG. 10 ; 
         FIG. 16  is a schematic perspective view of a second embodiment of the isolation sleeve shown in  FIG. 1 ,  FIG. 2 ,  FIG. 9  and  FIG. 10 ; 
         FIG. 17  is a schematic sectional view of the isolation sleeve shown in  FIG. 16 ; 
         FIG. 18  is a schematic sectional view of a fifth embodiment of the electric pump according to the present application; 
         FIG. 19  is a schematic sectional view of a sixth embodiment of the electric pump according to the present application; 
         FIG. 20  is a schematic perspective view of the isolation sleeve shown in  FIG. 19 ; and 
         FIG. 21  is a schematic sectional view of the isolation sleeve shown in  FIG. 20 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present application is further illustrated hereinafter in conjunction with drawings and specific embodiments. 
     The electric pump in the following embodiments can provide a working medium of a vehicle thermal management system with the power to flow, wherein the working medium is clean water or 50% aqueous solution of ethylene glycol. 
     Referring to  FIG. 1 ,  FIG. 1  is a schematic structural view of the first embodiment of the electric pump. The electric pump  100  includes a pump housing, a rotor assembly  3 , a stator assembly  4 , a pump shaft  5  and an electronic control board  9 . The pump housing includes a first housing  1 , a second housing  2  and a bottom cover  6 . The first housing  1 , the second housing  2  and the bottom cover  6  are relatively fixed to each other. In the present embodiment, a connection portion between the first housing  1  and the second housing  2  is provided with a first annular sealing ring  10 . A structure with the first annular sealing ring  10  can prevent the working medium from oozing out at the connection portion, and prevent an external medium from infiltrating into a pump inner chamber. The pump housing can form the pump inner chamber, and the pump inner chamber is partitioned into a first chamber and a second chamber. Specifically, in the present embodiment, the electric pump  100  further includes an isolation sleeve  7 . The first chamber  30  is arranged on one side of the isolation sleeve  7 , and the second chamber  40  is arranged on another side of the isolation sleeve  7 . The working medium can flow through the first chamber  30 , while no working medium flows through the second chamber  40 . The rotor assembly  3  is arranged in the first chamber  30 , and includes a rotor  31  and an impeller  32 . Part of the impeller  32  is arranged in the isolation sleeve  7 , the stator assembly  4  and the electronic control board  9  are arranged in the second chamber  40 , and the stator assembly  4  is electrically connected to the electronic control board  9 . In the present embodiment, a second annular sealing ring  20  is provided between the isolation sleeve  7  and the pump housing, and the structure with the second annular sealing ring  20  can form two defenses, which can totally ensure that the external medium does not infiltrate into the second chamber  40 . 
     Referring to  FIG. 1 , the first housing  1  is an injection molding part, and is provided with an inlet  11  and an outlet  12  injection molding. When the electric pump  100  is in operation, the working medium enters the first chamber  30  through the inlet  11 , and then leaves the first chamber  30  through the outlet. When the electric pump  100  is in operation, a control circuit on the electronic control board  9  is connected to an external power supply by inserting a connector (not shown in the figure) into a socket  80  of the electric pump  100 , and the control circuit controls an electric current passing through the stator assembly  4  to change according to a certain rule, thereby enabling the stator assembly  4  to generate a varying magnetic field. The rotor  31  of the rotor assembly  3  rotates around the pump shaft  5  under the action of the magnetic field, thereby enabling the working medium entering the first chamber  30  to rotate with the rotor  31 . A centrifugal force generates power for flowing, and the working medium leaves the first chamber  30  due to the centrifugal force. 
     Referring to  FIG. 1 ,  FIG. 1  is a schematic structural view of the first embodiment of the electric pump according to the present application. The electric pump  100  further includes a heat dissipation plate  8 , and the heat dissipation plate  8  and the pump housing are separately arranged. The “separately arranged” refers to that the heat dissipation plate and the pump housing are two different parts formed by independent processing. The pump housing may be formed by fixedly connecting two or more parts, and the heat dissipation plate  8  is fixedly connected to the pump housing. The isolation sleeve  7  includes a bottom portion  71 , and the bottom portion  71  is closer to the electronic control board  9  than a top portion  77 . In the present embodiment, the bottom portion  71  includes an upper surface  711  and a lower surface  712 , the lower surface  712  is closer to the electronic control board  9  than the upper surface  711 , at least part of the upper surface  711  can be in contact with the working medium in the first chamber  30 , and at least part of the lower surface  712  is exposed to the second chamber. At least part of the heat dissipation plate  8  is arranged between the electronic control board  9  and the bottom portion  71 , and at least part of the bottom portion  71  is in direct contact with at least part of the heat dissipation plate  8 . At least part of the electronic control board  9  is in direct contact with at least part of the heat dissipation plate  8 , or silicone grease or silica gel is filled between at least part of the electronic control board  9  and at least part of the heat dissipation plate  8 , or heat conducting patches are provided between at least part of the electronic control board  9  and at least part of the heat dissipation plate  8 . In the present embodiment, the silicone grease or the silica gel is filled between at least part of the electronic control board  9  and at least part of the heat dissipation plate  8 . At least part of the electronic control board  9  may be in direct contact with at least part of the heat dissipation plate  8 , or the heat conducting patches may be provided between at least part of the electronic control board  9  and at least part of the heat dissipation plate  8 . Such arrangement can better realize heat conduction among the isolation sleeve  7 , the heat dissipation plate  8  and the electronic control board  9 , which is beneficial to the heat dissipation of the electronic control board  9 , thereby prolonging the service life of the electric pump. The “heat conducting patch” in the present embodiment refers to a patch, formed by curing of the silica gel, that has a certain viscosity and can be directly bonded. The stator assembly  4  is electrically connected to the electronic control board  9 . The stator assembly  4  includes stators  41  and pins  42 , and the heat dissipation plate  8  is located between the stator  41  and the electronic control board  9 . With an end of the stator  41  close to the second housing  2  defined as an upper end and another end thereof close to the bottom cover  6  defined as a lower end, the heat dissipation plate  8  is arranged close to the lower end of the stator  41 . Such an arrangement allows the heat dissipation plate  8  to be closer to the electronic control board  9 , thereby facilitating the heat dissipation of the electronic control board  9 . In the present embodiment, the pump inner chamber is partitioned into the first chamber  30  and the second chamber  40  by the isolation sleeve  7 . Specifically, the first chamber  30  is arranged on one side of the isolation sleeve  7 , and the second chamber  40  is arranged on another side of the isolation sleeve  7 . 
     Referring to  FIG. 2 ,  FIG. 2  is a schematic sectional view of the second embodiment of the electric pump. Compared with the first embodiment of the electric pump, in the electric pump  100   a , the silicone grease or the silica gel  90  is filled between at least part of the lower surface  712  of the bottom portion  71  of the isolation sleeve  7  and at least part of the heat dissipation plate  8 . The heat conducting patches may be provided between at least part of the lower surface  712  of the bottom portion  71  of the isolation sleeve  7  and at least part of the heat dissipation plate  8 . The “heat conducting patch” refers to the patch, formed by curing of the silica gel that has a certain viscosity and can be directly bonded. In the present embodiment, the lower surface  712  of the bottom portion  71  of the isolation sleeve  7  is coated with the silicone grease or the silica gel  90 , or a portion of the heat dissipation plate  8  corresponding to the lower surface  712  of the bottom portion  71  of the isolation sleeve  7  is coated with the silicone grease or the silica gel  90 . Such an arrangement can prevent the heat conduction among the isolation sleeve  7 , the heat dissipation plate  8  and the electronic control board  9  from being adversely affected due to the decrease of a contact area between the heat dissipation plate  8  and the isolation sleeve  7  in a case that the lower surface  712  is machined unevenly, and can prevent the heat dissipation efficiency of the electronic control board  9  from being reduced. In the present embodiment, other features of the electric pump are the same as those of the first embodiment of the electric pump, and will not be described herein again. 
     Referring to  FIGS. 3 to 6 , a central hole  81  and multiple avoidance holes  82  are provided at a center of the heat dissipation plate  8 . The avoidance holes  82  are arranged corresponding to part of the pins  42  and part of the stators  41 , which can prevent structural interference when the heat dissipation plate is assembled. The heat dissipation plate  8  is made of metal, specifically, made of copper or aluminum. Referring to  FIG. 6 , the heat dissipation plate  8  is fixedly connected to the pump housing. The heat dissipation plate  8  includes multiple through holes  83 , and the through holes  83  are distributed in a circumferential array or uniformly distributed. The pump housing includes multiple columns  21 , and the columns  21  are distributed in the circumferential array or evenly distributed. The columns  21  are integrally formed with the pump housing or fixedly connected with the pump housing. The columns  21  are arranged corresponding to the through holes  83 , and the heat dissipation plate  8  is fixedly connected with the pump housing by riveting the columns  21 . In the present embodiment, the heat dissipation plate  8  is fixedly connected to the second housing  2 , the columns  21  are arranged on the second housing  2 , the columns  21  are integrally formed with the second housing  2  or fixedly connected with the second housing  2 , and the through holes  83  are arranged corresponding to the columns  21 . After the through holes  83  are arranged corresponding to the columns  21 , part of the columns  21  are still exposed. The heat dissipation plate  8  is fixedly connected with the second housing  2  by riveting the columns  21 . Such an arrangement enables the connection between the heat dissipation plate  8  and the second housing  2  to be more reliable. Apparently, other connection modes may also be used. For example, the pump housing is formed with multiple threaded holes, the threaded holes are distributed in the circumferential array or evenly distributed, the through holes  83  on the heat dissipation plate  8  are arranged corresponding to the threaded holes of the pump housing, and the heat dissipation plate  8  is fixedly connected with the pump housing through screws and bolts. Apparently, the heat dissipation plate  8  may be connected with the pump housing by welding. 
     Referring to  FIG. 7  and  FIG. 8 ,  FIG. 7  and  FIG. 8  are schematic structural views of the electronic control board shown in  FIG. 1  and  FIG. 2 . The electronic control board  9  includes a base board  91  and electronic components  92 . The base board  91  includes a front surface  911  and a back surface  912 . In the present embodiment, the front surface  911  and the back surface  912  are arranged substantially in parallel, where the “substantially” refers to that the parallelism of the back surface is less than or equal to 1 mm with the front surface as a reference surface. Referring to  FIG. 1  or  FIG. 2 , the front surface  911  of the base board  91  is closer to the lower surface  712  than the back surface  912 , and a clearance is formed between the front surface  911  of the base board  91  and the heat dissipation plate  8 . At least part of the electronic components  92  are arranged between the front surface  911  and the heat dissipation plate  8 . The electronic components  92  include heat-generating electronic components (not shown in the figure), and at least part of the heat-generating electronic components are arranged on the front surface  911  of the base board  91 . In the present embodiment, the heat-generating electronic components include diodes, MOS tubes, inductors, resistors, capacitors and the like. Referring to  FIG. 1  or  FIG. 2 , the silicone grease or the silica gel  90  is filled between at least part of the heat dissipation plate  8  and at least part of the heat-generating electronic components (not shown in the figure), or the heat conducting patches are provided between at least part of the heat dissipation plate  8  and at least part of the heat-generating electronic components (not shown in the figure). Referring to  FIG. 7 , at least upper surfaces of the heat-generating electronic components are coated with the silicone grease or the silica gel  90  or the heat conducting patches, where the “upper surfaces” refer to surfaces of the heat-generating electronic components not connected with the electronic control board  9 . Apparently, the silicone grease or the silica gel  90  or the heat conducting patches may be coated on the heat dissipation plate  8  corresponding to the heat-generating electronic components  92 . Such an arrangement can conduct the heat generated by the heat-generating electronic components to the heat dissipation plate  8  through the silicone grease or the silica gel or the heat conducting patches, which is beneficial to the heat dissipation of the electronic control board  9 , thereby prolonging the service life of the electric pump. Referring to  FIG. 1  or  FIG. 2 , the height of the coated silicone grease or the silica gel  90  or the heat conducting patch is equal to a distance between the electronic control board  9  in  FIG. 1  or  FIG. 2  and the heat dissipation plate  8  in  FIG. 1  or  FIG. 2 , which can totally ensure that the silicone grease or the silica gel  90  or the heat conducting patch is in full contact with the electronic control board  9  and the heat dissipation plate  8 , which is beneficial to the heat dissipation of the electronic control board  9 , thereby prolonging the service life of the electric pump. Apparently, at least part of the heat dissipation plate  8  may be in direct contact with at least part of the heat-generating electronic components. Specifically, the heat dissipation plate  8  may be processed into other shapes with different thicknesses according to the height of the heat-generating electronic components, thereby allowing the heat dissipation plate  8  to be in direct contact with the heat-generating electronic components without coating the silicone grease or silica gel, which can also realize the heat dissipation of the electronic control board  9 . The “heat conducting patch” refers to the patch, formed by curing of the silica gel that has a certain viscosity and can be directly bonded. 
     Referring to  FIG. 3  and  FIG. 4 , the heat dissipation plate  8  is made of metal. In the present embodiment, the heat dissipation plate  8  is made of copper or aluminum. The thickness of the heat dissipation plate  8  is greater than or equal to 0.2 mm. In the present embodiment, the thickness of the heat dissipation plate  8  is greater than or equal to 0.2 mm and less than or equal to 1.5 mm. Such an arrangement not only can reduce a total weight of the electric pump, but also can reserve a certain space between the heat dissipation plate  8  and the heat-generating electronic components for filling the silicone grease or silica gel or the heat conducting patches, while ensuring the strength of the heat dissipation plate  8 , thereby having a good heat dissipation effect on the electronic control board  9 . Apparently, the thickness of the heat dissipation plate  8  may be greater than 1.5 mm. In this case, the heat dissipation plate  8  can be processed into other shapes with different thicknesses according to the height of the heat-generating electronic components. The heat dissipation plate  8  is in direct contact with the heat-generating electronic components without coating the silicone grease or silica gel. The heat dissipation plate  8  includes a first surface  85 , where the “first surface” refers to a surface in direct contact with the electronic control board  9  in  FIG. 1  or  FIG. 2  or a surface abutting against the silicone grease or silica gel or the heat conducting patches coated between the electronic control board  9  and the first surface. Referring to  FIG. 1 , the first surface  85  is in direct contact with at least part of the heat-generating electronic components in  FIG. 7 , or referring to  FIG. 2 , the silicone grease or silica gel  90  is filled between at least part of the first surface  85  of the heat dissipation plate  8  and at least part of the heat-generating electronic components, or the heat conducting patches are provided between at least part of the first surface  85  of the heat dissipation plate  8  and at least part of the heat-generating electronic components. An area of the first surface  85  of the heat dissipation plate  8  is defined as a first area. Referring to  FIG. 7  and  FIG. 8 , a zone, in which the base board  91  is covered by the heat-generating electronic components arranged on the front surface  911  of the base board  91 , is defined as a first zone, an area of the first zone is defined as a second area, and the first area is greater than or equal to the second area. Such an arrangement can fully ensure that there is a large contact area between the heat-generating electronic components arranged on the front surface  911  of the base board  91  and the heat dissipation plate  8 , thereby facilitating the heat dissipation. 
     Referring to  FIG. 9  and  FIG. 10 ,  FIG. 9  is a schematic sectional view of the third embodiment of the electric pump according to the present application.  FIG. 10  is a schematic sectional view of the fourth embodiment of the electric pump according to the present application. Referring to  FIG. 9  to  FIG. 12 , an electronic control board  9 ′ includes a base board  91 ′ and electronic components  92 ′. The base board  91 ′ includes a front surface  911 ′ and a back surface  912 ′. In the present embodiment, the front surface  911 ′ and the back surface  912 ′ are arranged substantially in parallel, where the “substantially” refers to that the parallelism of the back surface is less than or equal to 1 mm with the front surface as a reference surface. The electronic components  92 ′ are arranged on the back surface  912 ′ of the base board  91 ′, the front surface  911 ′ of the base board  91 ′ is closer to the lower surface  712  of the bottom portion  71  of the isolation sleeve  7  than the back surface  912 ′. The heat dissipation plate  8  is made of metal. Referring to  FIG. 9  and  FIG. 12 , at least part of the heat dissipation plate  8  is in direct contact with the front surface  911 ′ of the base board  91 ′, or referring to  FIG. 10  and  FIG. 12 , the silicone grease or silica gel  90  is filled between at least part of the heat dissipation plate  8  and the front surface  911 ′ of the base board  91 ′, or the heat conducting patches are provided between at least part of the heat dissipation plate  8  and the front surface  911 ′ of the base board  91 ′. The area of the first surface  85  of the heat dissipation plate  8  in  FIG. 3  is defined as the first area, the zone of the base board  91 ′ covered by the electronic components  92 ′ in  FIG. 11  is defined as the first zone, the area of the first zone is defined as the second area, and the first area is greater than or equal to the second area. Compared with the first embodiment of the electric pump, in the third and fourth embodiments of the electric pump, the electronic components are mounted at different positions on the electronic control board. Specifically, the electronic components  92 ′ are arranged on the back surface  912 ′ of the base board  91 ′. Such an arrangement enables an axial dimension of the electric pump to be more compact. Other features of the third and fourth embodiments of the electric pump are the same as those of the first embodiment of the electric pump, and will not be described herein again. 
     Referring to  FIG. 13  and  FIG. 14 ,  FIG. 13  and  FIG. 14  are schematic structural views of the first embodiment of the isolation sleeve. The isolation sleeve is made of metal having low or no magnetic permeability, where the “low magnetic permeability” refers to that the relative magnetic permeability μr is less than 20. In the present embodiment, the isolation sleeve  7  is made of austenitic stainless steel such as the austenitic stainless steel 316L, 304, and 310s. The isolation sleeve  7  includes a sidewall  70  and the bottom portion  71 . Referring to  FIG. 1  or  FIG. 2  or  FIG. 9  or  FIG. 10 , the sidewall  70  is configured to isolating the stator assembly  4  from the rotor assembly  3 . In the present embodiment, the stator assembly  4  is sleeved on a periphery of the sidewall  70 , and the rotor  31  is sleeved to an inner circumference of the sidewall  70 . The sidewall  70  includes an inner surface  701  and an outer surface  702 , the inner surface  701  is arranged closer to a central shaft of the isolation sleeve  7  than the outer surface  702 . In the present embodiment, the inner surface  701  and the outer surface  702  of the sidewall  70  both are smooth surfaces, that is, both the inner surface  701  and the outer surface  702  are not provided with other structures. Apparently, the inner surface  701  and the outer surface  702  of the sidewall  70  may be provided with other structures. The bottom portion  70  includes the upper surface  711  and the lower surface  712 , and the upper surface  711  is closer to an opening side of the isolation sleeve  7  than the lower surface  712 . In the present embodiment, the upper surface  711  and the lower surface  712  are both smooth surfaces, that is, both the upper surface  711  and the lower surface  712  are not provided with other structures. Apparently, the upper surface  711  and the lower surface  712  of the bottom portion  71  may be provided with other structures. A minimum distance between a main body portion of the upper surface  711  and a main body portion of the lower surface  712  is defined as a first distance. The “main body portion of the upper surface  711 ” refers to the feature that accounts for the main portion of the upper surface  711 , and the “feature that accounts for the main portion” refers to that the feature accounts for more than 50% of the area of the upper surface  711 . The “main body portion of the lower surface  712 ” refers to the feature that accounts for the main portion of the lower surface  712 , and the “feature that accounts for the main portion” refers to that the feature accounts for more than 50% of the area of the lower surface  712 . In the present embodiment, the upper surface  711  and the lower surface  712  are both smooth surfaces, that is, both the upper surface  711  and the lower surface  712  are not provided with other structures. A thickness t 1  of the sidewall  70  is less than or equal to a thickness of the bottom portion  71 . The “thickness of the sidewall  70 ” refers to a minimum distance between the inner surface  701  and the outer surface  702  of the sidewall  70 . The “thickness of the bottom portion  71 ” is the first distance. On the one hand, such an arrangement can ensure the strength of the bottom portion  71  of the isolation sleeve, and on the other hand, referring to  FIG. 1 , the thin sidewall  70  is more beneficial to the heat conduction among the working medium, the sidewall  70  of the isolation sleeve  7  and the stator assembly  4 , thereby facilitating the heat dissipation of the stator assembly  4 . In the present embodiment, the thickness of the sidewall  70  is less than or equal to 1.5 mm. The isolation sleeve  7  is made of stainless steel. Specifically, the isolation sleeve  7  is made of austenitic stainless steel. The isolation sleeve  7  is formed by stamping and stretching a metal plate. The isolation sleeve  7  is provided with a pump shaft position-limiting portion  72 , and the pump shaft position-limiting portion  72  is formed at the bottom portion  71 . Referring to  FIG. 1  or  FIG. 2 , the pump shaft position-limiting portion  72  protrudes toward the second chamber  40 . The heat dissipation plate  8  is provided with a through hole corresponding to the pump shaft position-limiting portion  72 , and the pump shaft position-limiting portion  72  passes through the through hole and is positioned to the heat dissipation plate  8 . Specifically, referring to  FIG. 3 , the through hole provided in the heat dissipation plate  8  corresponding to the pump shaft position-limiting portion  72  is the central hole  81  of the heat dissipation plate  8 . Referring to  FIG. 1  or  FIG. 2 , the lower surface  712  of the bottom portion  71  is arranged in contact with the heat dissipation plate  8 , except for the pump shaft position-limiting portion  72 , or a clearance between the lower surface  712  of the bottom portion  71  and the heat dissipation plate  8  is filled with the silicone grease or the silica gel, except for the pump shaft position-limiting portion  72 , or the clearance between the lower surface  712  of the bottom portion  71  and the heat dissipation plate  8  is provided with the heat conducting patches, except for the pump shaft position-limiting portion  72 . Such an arrangement ensures a large enough contact area between the bottom portion  71  of the isolation sleeve  7  and the heat dissipation plate  8 , or ensures that there is as much the silicone grease or the silica gel as possible filled between the bottom portion  71  and the heat dissipation plate  8 , which is beneficial to the heat conduction among the isolation sleeve  7 , the heat dissipation plate  8  and the electronic control board  9 , thereby facilitating the heat dissipation of the electronic control board  9 . In the present embodiment, the bottom portion  71  is integrally formed with the sidewall  70 . Apparently, the bottom portion  71  and the sidewall  70  may be separately arranged. Specifically, the bottom portion  71  may be fixedly connected with the sidewall  70  by welding or other means. 
     Referring to  FIG. 14  and  FIG. 15 , the pump shaft position-limiting portion  72  protrudes away from the opening side of the isolation sleeve  7 . The pump shaft position-limiting portion  72  is integrally formed with the isolation sleeve  7  by stamping and stretching. The pump shaft position-limiting portion  72  further includes a first position-limiting portion  721  (that is, the sidewall of pump shaft the position-limiting portion  72 ), the pump shaft  5  includes a second position-limiting portion  51 , the first position-limiting portion  721  is arranged corresponding to the second position-limiting portion  52 , and the pump shaft position-limiting portion  72  is fixedly connected with the pump shaft  5  by an interference fit and serves as a lower support of the pump shaft  5 . Such an arrangement can prevent circumferential rotation of the pump shaft  5 . The isolation sleeve  7  further includes a first step portion  75  and a second step portion  74 . The first step portion  75  further includes a first branch portion  752  and a first sub portion  751 . The first branch portion  752  is connected with the first sub portion  751 , and the first branch portion  752  is closer to the impeller  32  in  FIG. 1  than the first sub portion  751 . The second step portion  74  includes a second sub portion  742  and a second branch portion  741 . With the opening side of the isolation sleeve  7  as an upper side, the second step portion  74  is arranged above the first step portion  75 . A diameter of the first sub portion  751  is less than that of the second sub portion  742 , such that the impeller  32  in  FIG. 1  is partially located in the second sub portion  742 , which is beneficial to reducing an overall height of the electric pump  100  on the one hand, and can prevent the impurity particles from easily entering a flow zone between an outer wall of the rotor  31  in  FIG. 1  and an inner wall of the isolation sleeve  7  on the other hand, thereby avoiding the accumulation of the impurity particles in the electric pump and prolonging the service life of the electric pump. Referring to  FIG. 1  and  FIG. 14 , a minimum distance L between the second sub portion  742  and a peripheral surface of the impeller  32  in  FIG. 1  is less than or equal to 2 mm. Such an arrangement can prevent the impurity particles in the working medium from flowing into the flow zone between the outer wall of the rotor  31  and the inner wall of the isolation sleeve  7 , can prevent the accumulation of the impurity particles in the flow zone between the outer wall of the rotor  31  in  FIG. 1  and the inner wall of the isolation sleeve  7  in  FIG. 1 , and can prevent the rotor  31  in  FIG. 1  from being stuck by the impurity particles and from stalling, thereby prolonging the service life of the electric pump. 
     Referring to  FIG. 14 , the isolation sleeve  7  further includes a third step portion  73 . The third step portion  73  includes a third sub portion  731  and a third branch portion  732 . Referring to  FIG. 1 , the first annular sealing ring  10  is provided between the pump housing and the isolation sleeve  7 , and at least part of the first annular sealing ring  10  is in contact with at least part of the isolation sleeve  7 . In the present embodiment, the first annular sealing ring  10  is sleeved on the third sub portion  731 , at least part of the third branch portion  732  and at least part of the third sub portion  731  are in contact with at least part of the first annular sealing ring  10 , such that the first annular sealing ring  10  can be initially positioned on the isolation sleeve  7 , and the installation of the first annular sealing ring  10  becomes easier and more convenient. Referring to  FIG. 3  and  FIG. 4 , the third sub portion  731  of the third step portion  73  and the second branch portion  741  of the second step portion  74  form a fourth step portion. Referring to  FIG. 1 , the pump housing includes a step portion  13 , and the fourth step portion is arranged corresponding to the step portion  13 . In the present embodiment, the step portion  13  is arranged in the first housing  1 , and the fourth step portion is arranged corresponding to the step portion  13  of the first housing  1  in  FIG. 1 , which facilitates the positioning of the first housing  1  when the first housing  1  is mounted, thereby preventing the first housing  1  from laterally moving when the first housing  1  is mounted. Referring to  FIG. 1 , the second annular sealing ring  20  is arranged between the third sub portion  731  of the third step portion  73  and the second sub portion  742  of the second step portion  74 , at least part of the second branch portion  741  of the second step portion  74  is in contact with at least part of the second annular sealing ring  20 , such that two defenses can be formed, which fully ensures that the external medium and the working medium cannot infiltrate into the second chamber  40  in  FIG. 1 , thereby preventing the external medium and the working medium from entering the stator assembly and the circuit board and preventing the external medium and the working medium from damaging the stator assembly and the circuit board. 
     Referring to  FIG. 14 , a diameter of the pump shaft position-limiting portion  72  is defined as a first diameter Φ 1 , and a distance between a bottom surface of the pump shaft position-limiting portion  72  and the lower surface  712  of the bottom portion  71  is defined as a first distance H 1 . The first distance H 1  is less than or equal to the first diameter Φ 1 , which is advantageous for stretch forming. 
     Referring to  FIG. 16  and  FIG. 17 ,  FIG. 16  and  FIG. 17  are schematic structural views of the second embodiment of the isolation sleeve. An isolation sleeve  7 ′ is provided with a pump shaft position-limiting portion  72 ′, and the pump shaft position-limiting portion  72 ′ protrudes toward the second chamber  40 . A lower surface  712 ′ of a bottom portion  71 ′ is formed with an annular recess  73 ′, and the annular recess  73 ′ is closer to the sidewall  70 ′ than the pump shaft position-limiting portion  72 ′. Referring to  FIG. 1 , the pump shaft  5  is fixedly connected with the pump shaft position-limiting portion  72 ′, and the lower surface  712 ′ of the bottom portion  71 ′ is arranged in contact with the heat dissipation plate  8 , except for the annular recess  73 ′, or the clearance between the lower surface  712 ′ of the bottom portion  71 ′ and the heat dissipation plate  8  is filled with the silicone grease or the silica gel, except for the annular recess  73 ′, or the clearance between the lower surface  712 ′ of the bottom portion  71 ′ and the heat dissipation plate  8  is provided with the heat conducting patches, except for the annular recess  73 ′. Compared with the first embodiment of the isolation sleeve, the present embodiment can save the central hole  81  of the heat dissipation plate  8  in  FIG. 3 , thereby saving processing cost and improving the processing efficiency of the heat dissipation plate  8  and the electronic control board  9 . 
     Referring to  FIG. 1 ,  FIG. 2 ,  FIG. 9  and  FIG. 10 , when the electric pump is in operation, the first chamber  30  is filled with the working medium. On the one hand, as shown in  FIG. 1 , the isolation sleeve  7  is in direct contact with the heat dissipation plate  8 , or as shown in  FIG. 2 , the silicone grease or the silica gel is filled between the bottom portion  71  of the isolation sleeve  7  and at least part of the heat dissipation plate  8 ; and on the other hand, as shown in  FIG. 9 , an electronic control board  9 ′ is in direct contact with the heat dissipation plate  8 , or as shown in  FIG. 10 , the silicone grease or the silica gel  90  is filled between the electronic control board  9 ′ and the heat dissipation plate  8 , such that the isolation sleeve  7 , the heat dissipation plate  8  and the electronic control board are in direct or indirect contact with each other in sequence, and the working medium indirectly takes away part of the heat of the electronic control board  9 , thereby enabling the heat dissipation of the electronic control board  9  to be more efficient. 
     Referring to  FIG. 18 ,  FIG. 18  is a schematic sectional view of the fifth embodiment of the electric pump according to the present application. An electric pump  100   d  includes the electronic control board  9  and the heat dissipation plate  8 , and the electronic control board  9  includes the base board  91  and the electronic components  92 . The base board  91  is connected with the electronic components  92 . The silicone grease or the silica gel  90  is filled between the base board  91  and the heat dissipation plate  8 , or the heat conducting patches are provided between the base board  91  and the heat dissipation plate  92 . The pump housing includes the bottom cover  6 . The silicone grease or the silica gel  90  is filled between the bottom cover  6  and the base board  91 , or the heat conducting patches are provided between the bottom cover  6  and the base board  91 . In the present embodiment, the silicone grease or the silica gel  90  is filled between the base board  91  and the heat dissipation plate  8 , the silicone grease or the silica gel  90  is also filled between the bottom cover  6  and the base board  91 . Apparently, the heat conducting patches may be provided between the base board  91  and the heat dissipation plate  92 , the heat conducting patches may also be provided between the bottom cover  6  and the base board  91 . Compared with the first embodiment of the electric pump, on the one hand, such an arrangement increases the area of the silicone grease or the silica gel or the heat conducting patches, thereby improving the heat dissipation efficiency of the electronic control board  9 , and on the other hand, the silicone grease or the silica gel or the heat conducting patches arranged between the bottom cover  6  and the base board  91  allows part of the heat of the electronic control board  9  to be dissipated through the bottom cover  6 , thereby facilitating the heat dissipation of the electronic control board  9 . In the present embodiment, the electronic components  92  are arranged between the base board  91  and the heat dissipation plate  8 . Apparently, the electronic components may be arranged between the bottom cover  6  and the base board  91 . Other features of the present embodiment are the same as those of the first embodiment of the electric pump, and will not be described herein again. 
     Referring to  FIG. 19  to  FIG. 21 ,  FIG. 19  is a schematic sectional view of the sixth embodiment of the electric pump according to the present application.  FIG. 20  and  FIG. 21  are schematic structural views of the isolation sleeve in  FIG. 18 . In the present embodiment, an electric pump  100   e  includes an isolation sleeve  7 ″, and at least part of the isolation sleeve  7 ″ is arranged on the periphery of the rotor assembly  3 . The electric pump  100   e  further includes a heat dissipation plate  8 ″, and at least part of the heat dissipation plate  8 ″ is arranged between the isolation sleeve  7 ″ and the electronic control board  9 . Compared with other embodiments of the electric pump, in the present embodiment, a first chamber  30 ″ includes a chamber formed by part of the heat dissipation plate  8 ″ and the isolation sleeve  7 ″. In the present embodiment, the isolation sleeve  7 ″ is cylindrical, and a support portion of the pump shaft is not arranged on the isolation sleeve  7 ″, but is arranged on the heat dissipation plate  8 ″. When the electric pump  100   e  is in operation, part of the working medium can be in direct contact with part of the heat dissipation plate. In order to match with the structure of the isolation sleeve in the present embodiment, the electric pump  100   e  is provided with a sealing portion  50 , which can prevent the leakage of the working medium. In the present embodiment, the sealing portion  50  is arranged on the periphery of the isolation sleeve  7 ″. Apparently, the sealing portion  50  may be arranged on other portions to achieve a sealing effect. In the present embodiment, in order to facilitate the installation of the sealing portion  50 , the isolation sleeve  7 ″ is provided with a step portion  76 . Apparently, the isolation sleeve  7 ″ may not include the step portion  76 , and in this case, the sealing portion  50  may be arranged on other portions. Compared with other embodiments of the electric pump and the isolation sleeve, on the one hand, the processing method of the isolation sleeve in the present embodiment is relatively simpler, thereby facilitating reducing the processing cost, and on the other hand, part of the working medium can be in contact with the part of the heat dissipation plate, thereby improving the heat dissipation efficiency of the electronic control board. Other features of the present embodiment are the same as those of other embodiments of the electric pump and the isolation sleeve, and will not be described herein again. 
     It should be noted that, the above embodiments are merely for illustrating the present application, and are not intended to limit the technical solutions described in the present application. Although the present application is described in detail with reference to the above embodiments, it should be understood by those skilled in the art that, various modifications and equivalents can be made to the technical solutions of the present application without departing from the spirit and scope of the present application, all of which should be contained within the scope of the claims of the present application.