CN109654029B

CN109654029B - Automobile direct-current electronic water pump and impeller manufacturing method thereof

Info

Publication number: CN109654029B
Application number: CN201811301011.8A
Authority: CN
Inventors: 沈伟; 王�锋; 李娟�; 刘建军
Original assignee: Shanghai Jiding Industrial Co ltd
Current assignee: Shanghai Jiding Industrial Co ltd
Priority date: 2018-11-02
Filing date: 2018-11-02
Publication date: 2020-07-07
Anticipated expiration: 2038-11-02
Also published as: CN109654029A

Abstract

The invention discloses an automobile direct-current electronic water pump and a manufacturing method of an impeller thereof, belonging to the technical field of new energy automobile electronic water pumps, particularly adopting a mode of staggered and spaced arrangement of rigid impeller blades and vulcanized soft rubber impeller blades, and additionally endowing the impeller with a unique manufacturing method, so that reliable sealing is formed between the blades and the inner cavity wall of a cover body, the problem of lag in the time of forming reliable cooling water circulation can be effectively solved, and the consistent blades and the inner cavity wall of the cover body obviously avoid the generation of bubbles and turbulence, thereby eliminating noise; when high-speed cooling water enters the inner cavity of the cover body, the flexible soft rubber is firstly contacted with the high-speed cooling water, so that the instantaneous impact noise is reduced, and meanwhile, the kinetic energy conversion efficiency is improved; in addition, the impeller manufacturing method of the automobile direct-current electronic water pump obviously reduces the requirements of the production and manufacturing process of the blades and reduces the manufacturing cost.

Description

Automobile direct-current electronic water pump and impeller manufacturing method thereof

Technical Field

The invention relates to the technical field of new energy automobile electronic water pumps, in particular to an automobile direct-current electronic water pump and a manufacturing method of an impeller thereof.

Background

With the development of automobile electronic technology, an automobile electronic system is increasingly complex, the correlation with functional safety is continuously improved, any failure of safety-related software and hardware can bring serious consequences, and whether the system safety can be continuously ensured when a product fails or fails becomes a topic of concern, wherein the most concern is the problem of reliable heat dissipation of an internal system; the electronic water pump is widely applied to an automobile heat dissipation circulating system, and provides circulating flow power of a heat dissipation medium in the heat dissipation circulating system; after the automobile is started, the electronic control components can generate a large amount of heat, the heat must be discharged in time through the heat dissipation circulating system, the electronic control components can work within a normal temperature range, the reliability of the system is guaranteed, and the electronic water pump is a power source for heat conducting medium of the heat dissipation system to flow circularly.

The existing electronic water pump generally requires a self-suction function, namely, in the rotating process of an inner cavity of a cover body, an impeller blade and the wall of the inner cavity of the cover body have certain sealing performance, positive pressure is formed in a water outlet pipeline under the action of centrifugal force, vacuum is formed in a water inlet pipeline, and water is actively pressed into the inner cavity of the cover body by utilizing pressure difference;

there are three problems in this process: firstly, impeller blades are generally made of POM (polyoxymethylene), PA (polyamide) and PET (polyethylene terephthalate) engineering plastics, the materials are hard, and in order to meet certain sealing property, the edges of the blades are required to be attached to the inner cavity wall of the cover body relatively close, so that the requirement on the manufacturing process of the impeller is very high, gaps are not uniform in the actual process, or the gaps between the blades and the inner wall are not uniform, and finally poor sealing property is caused, water pressing is delayed, and the time of forming reliable cooling water circulation is delayed; secondly, when cooling water rapidly enters the inner cavity of the cover body, the cooling water collides with the blades of the high-speed impeller to generate large noise at the moment, the kinetic energy loss is large, and due to the continuous change of the size of the gap, a large amount of bubbles and noise are generated when the cooling water rapidly passes through the gap; thirdly, the phenomenon can lead to the impeller being in an unbalanced rotary motion state for a long time, and finally the impeller is abraded, so that the service life is shortened.

Disclosure of Invention

One of the purposes of the invention is to provide an automobile direct-current electronic water pump, which originally utilizes vulcanized soft rubber to form reliable sealing between blades and the wall of an inner cavity of a cover body, can effectively solve the problem of lag time of forming reliable cooling water circulation, and obviously avoids the generation of bubbles and turbulence between the blades and the wall of the inner cavity of the cover body in a consistent way; when high-speed cooling water enters the inner cavity of the cover body, the flexible soft rubber is firstly contacted with the high-speed cooling water, so that the instantaneous impact noise is reduced, and meanwhile, the kinetic energy conversion efficiency is improved; the second purpose is to provide the impeller manufacturing method of the automobile direct current electronic water pump, which remarkably reduces the manufacturing process requirements of the blades and reduces the manufacturing cost.

In order to solve the technical problems of lag in self-priming, high instantaneous noise, serious turbulence, unbalanced operation and short service life of an automobile electronic water pump in the prior art, the invention provides the following technical scheme: an automobile direct-current electronic water pump comprises a pump body, a cover body, an electric control plate, a stator, a rotor, a rotating shaft and an impeller; the cover body is fixedly arranged on the pump body, a water inlet pipeline is arranged on the cover body along the axis direction, a water outlet pipeline is arranged on the cover body along the tangential direction, the water inlet pipeline and the water outlet pipeline are communicated with an inner cavity of the cover body, the electric control board and the stator are encapsulated in the inner cavity of the pump body through epoxy resin glue and are electrically connected with each other, the rotating shaft is arranged along the axis of the stator, one end of the rotating shaft is fixed on the pump body, the other end of the rotating shaft extends to the inner cavity of the cover body, the rotor is arranged in the inner cavity of the pump body and is sleeved on the rotating shaft through a shaft sleeve; the method is characterized in that: the impeller comprises an impeller disc and a plurality of blades, the blades are uniformly distributed on the upper end surface of the impeller disc by taking the rotating shaft as the center, the blades are divided into a first group of blades and a second group of blades, the first group of blades and the second group of blades are arranged in a staggered and spaced mode, and the second group of blades are vulcanized soft rubber; the intersection point of the inner end of each blade of the first group of blades in the radial direction and the plane of the impeller disc is positioned on a first circumference, each blade of the first group of blades is arranged along the tangential direction of the first circumference, the intersection point of the inner end of each blade of the second group of blades in the radial direction and the plane of the impeller disc is positioned on a second circumference, and each blade of the second group of blades is arranged along the tangential direction of the second circumference; the blades all point to the rotation direction of the impeller, and the outer ends of the blades are all flush with the outer edge of the impeller disc.

Further, the invention provides an automobile direct current electronic water pump, wherein: the impeller comprises an impeller disc and a second group of blades, wherein the impeller disc is integrally formed on the impeller disc along the axis, and the inner end of each blade of the second group of blades is connected to the outer side wall of the impeller shaft sleeve along the generatrix direction of the impeller shaft sleeve.

Further, the invention provides an automobile direct current electronic water pump, wherein: and each blade of the second group of blades is internally provided with tensile prestress.

Preferably, the present invention provides an automotive dc electronic water pump, wherein: the circle diameter of the first circumference is larger than that of the second circumference, and the circle diameter of the first circumference is not smaller than the diameter of the water inlet pipeline.

Preferably, the present invention provides an automotive dc electronic water pump, wherein: each blade of the first group of blades comprises a rigid frame and a vulcanized soft rubber sheet, and the vulcanized soft rubber sheet is welded and fixed in the rigid frame.

Further, the invention provides an automobile direct current electronic water pump, wherein: the inner part of the vulcanized soft rubber sheet is provided with tensile prestress.

Preferably, the present invention provides an automotive dc electronic water pump, wherein: the transverse section of the first group of blades is arc-shaped.

Further, the invention provides an automobile direct current electronic water pump, wherein: the inner end, the outer end and the upper end of each blade of the first group of blades are all subjected to soft rubber vulcanization edge covering treatment.

In order to solve the technical problems of high manufacturing process requirement and high manufacturing cost of the automobile electronic water pump impeller in the prior art, the invention provides the following technical scheme: a method for manufacturing an impeller comprises the following steps:

integrally forming an impeller disc and an impeller shaft sleeve;

welding and fixing one end of each blade of the second group of blades on the outer side wall of the impeller shaft sleeve along the generatrix direction of the impeller shaft sleeve, pulling the other end of each blade of the second group of blades along the excircle tangential direction of the impeller shaft sleeve until the other end reaches the outer edge of the impeller disc, and then welding and fixing the lower end of each blade of the second group of blades on the upper end face of the impeller disc;

preparing the rigid frame, stretching the vulcanized soft rubber sheet to cover the rigid frame, and then fixing the vulcanized soft rubber sheet in the rigid frame along the inner edge of the rigid frame by welding, and removing the vulcanized soft rubber sheet beyond the inner edge of the rigid frame;

tightening and attaching the vulcanized soft rubber sheets removed in the steps to the edge of the rigid frame, welding the vulcanized soft rubber sheets to the edge of the rigid frame in a hot air welding mode for edge covering treatment, and removing redundant vulcanized soft rubber sheets;

arranging the first group of blades and the second group of blades processed in the steps on the impeller disc at intervals in a staggered mode, and fixing each blade of the first group of blades on the upper end face of the impeller disc in a welding and fixing mode;

and (6) balance correction.

Drawings

FIG. 1 is a schematic view of an automotive DC electronic water pump according to the present invention;

FIG. 2 is a schematic view of an impeller structure of a DC electronic water pump of an automobile according to a first embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an impeller of a DC electronic water pump of a second embodiment of the present invention;

FIG. 4 is a schematic view of an impeller blade structure of a third embodiment of an automotive DC electronic water pump according to the present invention;

FIG. 5 is a schematic view of an impeller blade of a fourth embodiment of an automotive DC electronic water pump according to the present invention;

FIG. 6 is a schematic view of an impeller blade structure of a fifth embodiment of an automotive DC electronic water pump according to the present invention;

fig. 7 is a schematic top view of an impeller of a fourth and fifth embodiments of the dc electric water pump of an automobile according to the present invention.

Wherein: 1. a pump body; 2. a cover body; 3. an electric control board; 4. a stator; 5. a rotor; 6. a rotating shaft; 7. an impeller; 8. a water inlet pipeline; 9. a water outlet pipeline; 10. an impeller disc; 11. a blade; 11a, a first set of blades; 11b, a second set of blades; 12. an impeller shaft sleeve; 13. a rigid frame; 14. vulcanizing the soft rubber sheet.

Detailed Description

The present invention will be described in further detail with reference to specific examples below:

example 1

As shown in fig. 1 and fig. 2, the embodiment provides an automotive direct-current electronic water pump, which includes a pump body 1, a cover body 2, an electric control plate 3, a stator 4, a rotor 5, a rotating shaft 6 and an impeller 7; the cover body 2 is fixedly arranged on the pump body 1, wherein the cover body 2 is provided with a water inlet pipeline 8 along the axis direction, a water outlet pipeline 9 along the tangential direction, the water inlet pipeline 8 and the water outlet pipeline 9 are both communicated with the inner cavity of the cover body 2, the electric control board 3 and the stator 4 are encapsulated in the inner cavity of the pump body 1 through epoxy resin glue and electrically connected with each other, the rotating shaft 6 is arranged along the axis of the stator 4, one end of the rotating shaft is fixed on the pump body 1, the other end of the rotating shaft extends to the inner cavity of the cover body 2, the rotor 5 is arranged in the inner cavity of the pump body 1 and sleeved on the rotating shaft 6 through a shaft sleeve, the impeller 7 is arranged in the inner cavity; the impeller 7 comprises an impeller disc 10 and a plurality of blades 11, the blades 11 are uniformly distributed on the upper end surface of the impeller disc 10 by taking the rotating shaft 6 as the center, wherein the blades 11 are divided into a first group of blades 11a and a second group of blades 11b, the first group of blades 11a and the second group of blades 11b are arranged in a staggered and spaced mode, and the second group of blades 11b are made of vulcanized soft rubber; the intersection point of the inner end of each blade of the first group of blades 11a in the radial direction and the plane of the impeller disc 10 is located at a first circumference, each blade of the first group of blades 11a is arranged along the tangential direction of the first circumference, the intersection point of the inner end of each blade of the second group of blades 11b in the radial direction and the plane of the impeller disc 10 is located at a second circumference, and each blade of the second group of blades 11b is arranged along the tangential direction of the second circumference; the blades 11 all point to the rotation direction of the impeller 7, and the outer ends of the blades 11 are all flush with the outer edge of the impeller disc 10; wherein the diameter of the circle of the first circumference is larger than the diameter of the circle of the second circumference, and the diameter of the circle of the first circumference is not smaller than the diameter of the water inlet pipeline 8 (the diameter of the circle of the first circumference is equal to the diameter of the water inlet pipeline 8 in the embodiment).

The working principle and the process of the embodiment are as follows: the magnet on the rotor of the brushless direct current electronic water pump and the impeller 7 are molded into a whole to form the rotor 5 of the motor, a direct injection molding shaft sleeve is arranged in the middle of the rotor and fixed in the pump body 1 through a high-performance ceramic shaft, the stator 4 and the electric control board 3 of the motor are encapsulated in the pump body 1 through epoxy resin glue, a layer of thin wall is arranged between the stator 4 and the rotor 5 for isolation, and the traditional mechanical shaft seal is not needed to be matched, so that the motor is completely sealed. The torque of the motor is generated by the magnetic field generated by the coil on the silicon steel sheet (stator) to drive the permanent magnet (rotor) to work and operate. And (3) magnetizing the magnet by n (n is an even number) stages to enable the magnet parts to mutually form a complete coupled magnetic system. When the magnetic poles generated by the stator coil and the magnetic poles of the magnets are opposite in different poles, namely the displacement angle phi between the two magnetic poles =0, the magnetic energy of the magnetic system is the lowest at the moment; when the magnetic poles rotate to the opposite same poles, namely the displacement angle phi between the two magnetic poles =2 pi/n, the magnetic energy of the magnetic system is maximum. After the external force is removed, the magnetic force can restore the magnet to the state of lowest magnetic energy because the magnetic poles of the magnetic system repel each other. The magnet then moves, causing the magnetic rotor to rotate.

The brushless direct current water pump is electronically commutated without using a carbon brush, the magnet rotor and the stator silicon steel sheet are provided with a multi-stage magnetic field, and the magnetic pole direction can be automatically changed after the magnet rotor rotates by an angle relative to the stator, so that the rotor always keeps repulsion in the same stage, and the brushless direct current magnetic force isolation pump has higher rotating speed and efficiency.

Generally, the impeller blades are made of POM, PA and PET engineering plastics and are hard in texture, the second group of blades 11b are arranged in the impeller blades at intervals in a staggered mode in the embodiment originally, the second group of blades 11b are made of vulcanized soft rubber, on one hand, the upper end of the vulcanized soft rubber is matched with the inner cavity wall of the cover body 2 to form effective sealing, the effect is superior to the matching of hard plastics and the inner cavity wall of the cover body 2, self-priming is reliable, the reliable cooling water circulation time is timely formed, in addition, the axial vibration in the rotating process of the impeller 7 is limited due to the fact that the upper end of the vulcanized soft rubber is attached to the inner cavity wall of the cover body 2, the problem of service life shortening caused by unbalance is avoided, although the capability of centrifugally driving cooling liquid by the second group of blades 11b made of the vulcanized soft rubber is weaker than that of rigid blades, the rigid first group of blades 11a are arranged at, the advantages are complemented; on the other hand, the upper ends of the second group of blades 11b made of vulcanized soft rubber are matched with the inner cavity wall of the cover body 2, and because the blades are made of soft materials, compared with the traditional rigid blades, the traditional blades need to control the gap between the upper end surface of the blades and the inner cavity wall of the cover body 2 with high precision during processing, if the gap is not uniform, more bubbles and turbulence can be generated in the rotating process of the impeller 7, and then noise is generated, so that the requirement of the soft materials on the matching precision of the blades is greatly reduced, and the processing process and the manufacturing cost are obviously simplified; in addition, because the diameter of the circle of the first circumference is larger than that of the circle of the second circumference, and the diameter of the circle of the first circumference is not smaller than that of the water inlet pipeline, the cooling water is firstly contacted with the second group of blades 11b made of vulcanized soft rubber, so that the generation of instantaneous noise is avoided, the second group of blades 11b made of rubber efficiently guides the cooling water to the water outlet pipeline 9, and the kinetic energy loss is extremely low.

Example 2

As shown in fig. 3, in order to further enhance the centrifugal effect of the second set of blades 11b on the cooling water, the impeller further comprises an impeller hub 12, the impeller hub 12 is integrally formed on the impeller disc 10 along the axis, and the inner end of each blade of the second set of blades 11b is connected to the outer side wall of the impeller hub 12 along the generatrix direction of the impeller hub 12; and each blade of the second group of blades 11b is internally provided with a tensile prestress; the surface tension is improved by tensioning and vulcanizing the soft rubber, which is more beneficial to the transmission efficiency of the high-speed cooling water, and the rest of the structure is the same as that of embodiment 1, and is not repeated herein.

Example 3

As shown in fig. 4, in order to further reduce the noise level, the present embodiment considers that the rigid first group of blades 11a is also partially made of vulcanized soft rubber, and the specific structure is that each blade of the first group of blades 11a includes a rigid frame 13 and a vulcanized soft rubber sheet 14, the vulcanized soft rubber sheet 14 is welded and fixed in the rigid frame 13, and the vulcanized soft rubber sheet 14 has a tensile prestress inside; the rest of the structure is the same as that of embodiment 1, and is not described herein.

Example 4

As shown in fig. 5 and 7, in order to further optimize the cooling water transfer path, avoid noise and reduce manufacturing cost, the transverse section of the first group of blades 11a is arc-shaped, and the inner end, the outer end and the upper end of each blade of the first group of blades 11a are all subjected to soft rubber vulcanization edge covering treatment; the rest of the structure is the same as that of embodiment 1, and is not described herein.

Example 5

As shown in fig. 6 and 7, the transverse cross section of the first group of blades 11a is arc-shaped, and each blade of the first group of blades comprises a rigid frame and a vulcanized soft rubber sheet, the vulcanized soft rubber sheet is welded and fixed in the rigid frame, and the vulcanized soft rubber sheet is internally provided with a tensile prestress; the rest of the structure is the same as that of embodiment 1, and is not described herein.

In order to further reduce the manufacturing cost and optimize the manufacturing process, the embodiment further provides a manufacturing method of the impeller, which includes the following steps:

integrally forming an impeller disc 10 and an impeller shaft sleeve 12;

welding and fixing one end of each blade of the second group of blades 11b on the outer side wall of the impeller shaft sleeve 12 along the generatrix direction of the impeller shaft sleeve 12, pulling the other end along the excircle tangential direction of the impeller shaft sleeve 12 until the outer edge of the impeller disc 10, and then welding and fixing the lower end of each blade of the second group of blades 11b on the upper end surface of the impeller disc 10;

preparing the rigid frame 13, stretching the vulcanized soft rubber sheet 14 to cover the rigid frame 13, and then fixing the vulcanized soft rubber sheet in the rigid frame 13 along the inner edge of the rigid frame 13 by welding, and removing the vulcanized soft rubber sheet 14 beyond the inner edge of the rigid frame 13;

tightly attaching the vulcanized soft rubber sheet 14 removed in the above steps to the edge of the rigid frame 13, welding the vulcanized soft rubber sheet 14 to the edge of the rigid frame 13 in a hot air welding manner for edge covering treatment, and removing the redundant vulcanized soft rubber sheet 14;

arranging the first group of blades 11a and the second group of blades 11b processed in the above steps on the impeller disc 10 at intervals in a staggered manner, and fixing each blade of the first group of blades 11a on the upper end surface of the impeller disc 10 in a welding and fixing manner;

and (6) balance correction.

Plastic welding is defined as: a plastic joining method for making melt plastic macromolecules mutually diffuse and tightly adhere together by means of pressure. Plastic welding is often used in production and maintenance, for example, the intake manifold in a car, which is common in our lives, welds two separate parts together by vibration friction welding; general plastic welding is divided into three categories:

1 Hot plate welding

Probably the simplest plastic welding technique, but this method is particularly suitable for welding large plastic parts requiring large welding surfaces, and generally a planar electric heating plate melts and softens two surfaces to be welded, then quickly removes the electric heating plate, merges the two surfaces and applies force to cool.

The method has the advantages of simple welding device, high welding strength, and relatively easy shape design of products and welding parts. But the product is softened by the heat generated by the hot plate, and the period is longer; the molten resin adheres to the electric heating plate and is not easy to clean (the phenomenon can be alleviated by the surface coating F4 of the electric heating plate), and impurities are formed for a long time to influence the bonding strength; the pressure and time are strictly controlled to ensure proper melting amount; when different kinds of resins or metals are bonded to the resin, insufficient strength may occur.

2 hot air welding

When the hot air flow is directly blown to the joint area, the filler wire which is made of the same material as the base material in the joint area is melted. The weld is formed by melting the filler material and the plastic to be welded together.

The welding equipment of the welding method is light and easy to carry, but the requirement on the welding skill of an operator is high.

3 heat bar and pulse welding

These two techniques are mainly used for welding of plastic films of small thickness. The two methods are similar, and both the two films are tightly pressed together, and the welding is completed by utilizing the instant heat generated by a hot bar or a nickel-chromium wire.

In the embodiment, the second and third welding methods are adopted, and the third welding method is adopted when the second group of blades 11b are welded to the impeller sleeve 12 and the upper end surface of the impeller disc 10, when the first group of blades 11a are welded to the upper end surface of the impeller disc 10, and when the vulcanized soft rubber sheet 14 is welded to the rigid frame 13; the second welding method is used for welding the vulcanized soft rubber sheet 14 to the edges of the first group of blades 11 a.

Finally, it should be noted that the above detailed description is only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention is described in detail with reference to the examples, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.

Claims

1. An automobile direct-current electronic water pump comprises a pump body (1), a cover body (2), an electric control plate (3), a stator (4), a rotor (5), a rotating shaft (6) and an impeller (7); the cover body (2) is fixedly arranged on the pump body (1), wherein the cover body (2) is provided with a water inlet pipeline (8) along the axial direction and a water outlet pipeline (9) along the tangential direction, the water inlet pipeline (8) and the water outlet pipeline (9) are both communicated with the inner cavity of the cover body (2), the electric control board (3) and the stator (4) are encapsulated in the inner cavity of the pump body (1) through epoxy resin glue and are electrically connected, the rotating shaft (6) is arranged along the axis of the stator (4), one end of the rotating shaft is fixed on the pump body (1), the other end of the rotating shaft extends to the inner cavity of the cover body (2), the rotor (5) is arranged in the inner cavity of the pump body (1) and sleeved on the rotating shaft (6) through a shaft sleeve, the impeller (7) is arranged in the inner cavity of the cover body (2) and sleeved on the rotating shaft (6), and the impeller (7) is fixedly connected with the rotor (5); the method is characterized in that: the impeller (7) comprises an impeller disc (10) and a plurality of blades (11), the blades (11) are uniformly distributed on the upper end surface of the impeller disc (10) by taking the rotating shaft (6) as the center, wherein the blades (11) are divided into a first group of blades (11 a) and a second group of blades (11 b), the first group of blades (11 a) and the second group of blades (11 b) are arranged in a staggered and spaced mode, and the second group of blades (11 b) are made of vulcanized soft rubber; the intersection point of the inner end of each blade (11) of the first group of blades (11 a) in the radial direction and the plane of the impeller disc (10) is located at a first circumference, each blade (11) of the first group of blades (11 a) is arranged along the tangential direction of the first circumference, the intersection point of the inner end of each blade (11) of the second group of blades (11 b) in the radial direction and the plane of the impeller disc (10) is located at a second circumference, and each blade (11) of the second group of blades (11 b) is arranged along the tangential direction of the second circumference; the blades (11) point to the rotation direction of the impeller (7), and the outer ends of the blades (11) are flush with the outer edge of the impeller disc (10); each blade (11) of the first group of blades (11 a) comprises a rigid frame (13) and a vulcanized soft rubber sheet (14), and the vulcanized soft rubber sheet (14) is welded and fixed in the rigid frame (13).

2. The automotive direct current electronic water pump according to claim 1, characterized in that: the impeller disc is characterized by further comprising an impeller shaft sleeve (12), the impeller shaft sleeve (12) is integrally formed on the impeller disc (10) along the axis, and the inner end of each blade (11) of the second group of blades (11 b) is connected to the outer side wall of the impeller shaft sleeve (12) along the generatrix direction of the impeller shaft sleeve (12).

3. The automotive direct current electronic water pump according to claim 2, characterized in that: each blade (11) of the second group of blades (11 b) is internally provided with tensile prestress.

4. The automotive direct current electronic water pump according to claim 1, characterized in that: the circle diameter of the first circumference is larger than that of the second circumference, and the circle diameter of the first circumference is not smaller than that of the water inlet pipeline (8).

5. The automotive direct current electronic water pump according to claim 1, characterized in that: the vulcanized soft rubber sheet (14) is internally provided with tensile prestress.

6. The automotive direct current electronic water pump according to claim 1, characterized in that: the transverse section of the first group of blades (11 a) is arc-shaped.

7. The automotive direct current electronic water pump according to claim 6, characterized in that: the inner end, the outer end and the upper end of each blade (11) of the first group of blades (11 a) are all subjected to edge covering treatment by vulcanized soft rubber.

8. An impeller manufacturing method relates to the automobile direct-current electronic water pump of any one of claims 1 to 7, and is characterized in that: the method comprises the following steps:

integrally forming an impeller disc (10) and an impeller shaft sleeve (12);

one end of each blade (11) of the second group of blades (11 b) is welded and fixed on the outer side wall of the impeller shaft sleeve (12) along the generatrix direction of the impeller shaft sleeve (12), the other end of each blade (11) of the second group of blades (11 b) is pulled along the excircle tangential direction of the impeller shaft sleeve (12) until the outer edge of the impeller disc (10), and then the lower end of each blade (11) of the second group of blades (11 b) is welded and fixed on the upper end face of the impeller disc (10);

preparing the rigid frame (13), stretching the vulcanized soft rubber sheet (14) to cover the rigid frame (13), and then fixing the vulcanized soft rubber sheet (14) in the rigid frame (13) along the inner edge of the rigid frame (13) by welding, and removing the vulcanized soft rubber sheet (14) beyond the inner edge of the rigid frame (13);

tightening and attaching the vulcanized soft rubber sheet (14) removed in the step to the edge of the rigid frame (13), welding the vulcanized soft rubber sheet to the edge of the rigid frame (13) in a hot air welding mode for edge covering treatment, and removing the redundant vulcanized soft rubber sheet (14);

arranging the first group of blades (11 a) and the second group of blades (11 b) processed in the steps on the impeller disc (10) at intervals in a staggered mode, and fixing each blade (11) of the first group of blades (11 a) on the upper end face of the impeller disc (10) in a welding and fixing mode;

and (6) balance correction.