CN103089655A

CN103089655A - Improved structure of shaft seal-free magnetic-drive pump

Info

Publication number: CN103089655A
Application number: CN2011103448035A
Authority: CN
Inventors: 简焕然; 王锦城; 施志贤; 施志宽
Original assignee: Assoma Inc
Current assignee: Assoma Inc
Priority date: 2011-11-04
Filing date: 2011-11-04
Publication date: 2013-05-08
Anticipated expiration: 2031-11-04
Also published as: CN104747457B; CN103089655B; CN104747457A

Abstract

The invention provides an improved structure of a shaft seal-free magnetic-drive pump, aims at improving rigidity of a fixed shaft, and particularly improving a metal magnetic-drive pump provided with a corrosion resisting lining to obtain a high-rigidity fixed shaft system. The improved structure of the shaft seal-free magnetic-drive pump is particularly improved aiming at below 200 DEG C high temperature and high corrosion resistance usages to improve rigidity of a rotor system arranged in the structure and meet high performance requirements. The improved structure of the shaft seal-free magnetic-drive pump comprises a high-rigidity metal supporting seat, a rear shaft hole seat, an impeller and a fixed shaft, wherein the high-rigidity metal supporting seat is an extending member arranged on the axial inner side of the inner diameter of a pump inlet, is covered by corrosion resistance fluoroplastics, and provides main supporting strength for the fixed shaft, the rear shaft hole seat is arranged at the bottom of a sealing rear cover and used for providing auxiliary support for the fixed shaft; the impeller is provided with a special flow channel design to lower inlet flow speed to provide low NPSHr and high-performance pumping outlet; and fixed shaft can be a single ceramic shaft or a high-rigidity compose fixed shaft, and the high-rigidity compose fixed shaft is composed of a ceramic shaft sleeve, a metal shaft and a sealing nut and used for supporting running of an inner rotor.

Description

Improved structure of magnetic driving pump

Technical Field

The invention relates to an improved structure of a magnetic drive pump, in particular to an improved fixed shaft structure of a cast iron magnetic drive pump with a corrosion-resistant lining, aiming at ensuring that the pump can have high-reliability operation capability at the temperature of 200 ℃ and simultaneously meeting the high-performance requirement required by pump conveying, the invention improves a fixed shaft supporting structure and a related runner structure of a cast iron pump shell so as to increase the supporting rigidity of the fixed shaft to reduce adverse factors of fluoroplastic structural members influenced by the temperature, improve the performance of the pump and improve the reliability and the service life.

Background

According to the general shaftless magnetic driving pump, it has been widely used in many corrosion-resistant or leakage-proof applications, and the structure has two types, i.e. a fixed shaft and a rotating shaft, wherein the supporting mode of the fixed shaft has two-end support and cantilever support, and the material can be divided into plastic material and metal shell with plastic lining; the front end and the rear end of the fixed shaft are supported by an inlet axis supporting tripod and a sealed rear cover shaft hole seat which are made of plastic materials, the fixed shaft is supported by the rear cover bottom part of the fixed shaft, but the strength of the plastic is reduced along with the rise of the operation temperature, and the strength of the supporting tripod and the shaft hole seat is reduced along with the reduction of the strength of the supporting tripod and the shaft hole seat, so that the deflection and the displacement of the pump fixed shaft are caused; the fixed shaft rear cantilever support is supported by the bottom of the metal reinforced plastic rear cover, the support strength of the support is that the radial force applied to the cantilever fixed shaft can be distributed on the rear cover structure to reduce the deformation of the rear cover and improve the holding force of the fixed shaft, but the strength of the support is limited by the temperature limit of the reinforced fiber plastic of the rear cover structure; the following references will be used to further illustrate the problems associated with a fixed shaft for a magnetically driven pump and the potential problems that may be associated therewith.

The first citation case:

US patent No. 7033146, filed 2006, describes a bearing design for dry running of a magnetic drive pump, but the drawing shows a structure of a double-side supporting fixed shaft of a conventional plastic magnetic drive pump, in which a spider is located in an inner diameter space of a pump inlet and extends axially through a hub hole of a vane, a shaft fixing seat is provided at a rear end of the spider and is located inside the hub hole of the vane for supporting one end of the fixed shaft, the spider of the present citation has been reduced in flow resistance to an inlet flow passage as much as possible, a rear cover is a cup-shaped housing structure, a shaft hole seat is provided at a bottom and has no through hole for supporting the other end of the fixed shaft, strength of the plastic spider and the rear cover is easily reduced by temperature, and the drawing of the citation shows that in order to reduce influence of the spider on the inlet flow passage, a length of the spider is intentionally extended so that the shaft seat passes through the hub hole of the vane, but radial supporting force of the spider is greatly reduced, is only suitable for low-temperature and low-power application;

citation II:

US patent No. 7057320 Mechanical drive system operating by a magnetic force pump, the present citation describes the structure and design of the outer rotor of a magnetic drive pump, but the drawing clearly shows the structure of a double-side supporting fixed shaft of a conventional plastic magnetic drive pump, a tripod is located in the inner diameter space of the pump inlet and is integrated with the front cover of the pump to form a forming structure, the tripod extends axially to the vicinity of the inlet of the impeller blade, a thrust bearing is mounted on the end surface of a shaft fixing seat of the tripod, the thrust bearing is located on a hub plate of the impeller but protrudes from the inlet side of the impeller, a rear cover is a cup-shaped shell structure, the bottom of the shell is provided with a shaft hole seat without any through hole for supporting the other end of the fixed shaft, the citation is to reduce the flow resistance of the shaft fixing seat of the tripod and the thrust bearing to the inlet channel, the design method is to enlarge the inlet of the impeller to make the inner diameter larger than the inlet of the pump to reduce the resistance of, that is, the fluid will pass through a section of flow channel with enlarged inner diameter to the inlet of the impeller after passing through the inlet of the pump, and the larger the angle of the flow channel is, the more the flow resistance is increased.

Citation three:

chinese patent CN2482597Y Magnetic drive resistance fluorine plastic liner pump in 2002, the cited reference is a Magnetic drive pump with plastic lining metal shell, aiming at explaining the structure and corrosion resistance of the fluoroplastic lining, there is a shaft support frame integrally formed with the fluoroplastic lining, the fluoroplastic back cover is a cup-shaped shell structure, there is a shaft hole seat and no through hole at the bottom to support the other end of the fixed shaft, but it is also pointed out in its text that the support structure composed of fluoroplastic and the fixed shaft supported at both sides will deform elastically, and can buffer the vibration of the shaft load when the pump is running, but the cited reference does not further explain whether the structural strength and reliability for high temperature application at 200 ℃ are suitable.

Fourth citation:

US5895203, 1999, the present citation is a magnetically driven pump with a plastic lined metal housing, and is a fixed shaft structure supported at both sides, a detachable support tripod is installed at the inner diameter of the pump inlet, which is provided with an outer ring part for installing at the inner ring surface of the pump inlet, a shaft fixing seat is installed at the center for providing the front end support of the fixed shaft, a reinforcing material is installed inside the support tripod, and a complete corrosion-resistant material coats the surface thereof to improve the resistance of the front end support of the fixed shaft to stress and vibration, but it is also emphasized that the diameter of the front end of the fixed shaft must be smaller than the diameter of the rear end, so that the outer diameter of the shaft fixing seat supporting the tripod can be reduced, and the nose is made into a smooth curved surface according to the flow requirement, so that the flow resistance of the impeller inlet can be reduced when the front end of the fixed shaft is located at the pump inlet.

Fifth citation:

US6280156B1 magnetic coupled rotary pump in 2001, the magnetic drive pump of this citation is an outer rotor type, the original emphasizes that the structure of the metal vertical shaft magnetic drive pump can discharge the delivery liquid completely, its fixed shaft is a structure of unilateral support, its unilateral support structure of the fixed shaft is supported by tripod and conical shaft base at the pump inlet, tripod and conical shaft base are connected with the front cover of the metal pump, or locked on the front cover of the metal pump, because the conical shaft base is located in the inner diameter space of the pump inlet flow channel, therefore, the inner diameter of the cylindrical surface of the inlet flow channel must be increased along with the conical shaft base; the metal bearing of the impeller is arranged in the inner diameter of the axial part of the hub extending towards the inlet side and is used for being coupled with the shaft sleeve and the thrust bearing at the tail end of the conical shaft seat, so the curved surface of the conical shaft seat which is gradually increased in the inclined direction can be smoothly connected with the curved surface of the axial part of the hub of the impeller, and the inlet of the impeller is matched with the outer diameter of the axial part of the hub to adopt a large-caliber design, so the current scheme is feasible; however, if the fluoroplastic lining and the outer surface of the liquid receiving body are encapsulated and the impeller is made of fluoroplastic, the outer diameters of the tripod, the shaft seat and the axial portion of the hub must be added with twice encapsulation thickness, usually, the thickness of a single side is more than 3mm, namely, the outer diameter is increased by more than 6mm, the outer diameter does not contain the outer diameter increased by the encapsulation thickness required by the structure, in order to overcome the corrosivity of hydrofluoric acid, a metal reinforcing sheet must be arranged inside the hub plate of the impeller made of fluoroplastic, the hub plate comprises the axial portion of the hub which extends axially, so that the structural strength and the torque transmission capability of the hub are improved, a metal bearing arranged on the inner diameter of the axial portion of the hub must be changed into a ceramic bearing with the thickness equivalent to that of the shaft sleeve, and the thickness of the axial portion of the hub must be 3mm together with the thickness of the both sides, if only the original conical shaft seat is encapsulated, the outer diameter of the conical curved surface is inevitably increased, but the outer diameter is still smaller than the outer diameter of the axial part of the hub, therefore, the metal part of the conical shaft seat must change its inclination to increase its outer diameter, after encapsulation, the conical shaft seat can be smoothly connected with the curved surface of the axial portion of the hub of the impeller, i.e. the cylindrical surface of the pump inlet flow channel inner diameter must have a large expansion angle to match the curved surface of the conical shaft seat and the outer diameter of the axial portion of the hub, this results in the impeller inlet, which has previously been designed with a larger bore, having to be oversized, the fluid from the pump inlet having to be at a short axial distance, at a large divergent angle towards the impeller inlet, it must also be accelerated through a tripod of greatly increased thickness, under such various limitations, the low flow resistance of the original metal pump cannot be obtained and the design difficulty of the pump impeller is greatly increased; another problem of the fluoroplastic impeller is that when the weight of the impeller is greatly reduced, the center of mass of the rotor system formed by the rotor and the impeller moves to the outer rotor side, i.e., the back side of the impeller and the position of the bearing is located at the inner diameter of the axial portion of the hub, which easily causes the length and position of the bearing to be unable to effectively cover the center of mass of the rotor system, and the service life is unable to be ensured.

Six citations:

US patent No. 7101158B2 hydralic balancing magnetic driving centrifugal pump in 2001, the cited reference is for explaining the problem of axial thrust balance of the magnetic driving pump, but it is clear in the cited reference that its fixed shaft is of a constant diameter structure, and when its supporting tripod is installed in the inner diameter of the pump inlet, the outer diameter of the shaft fixing seat of the supporting tripod is too large, which affects the impeller inlet flow passage and reduces the pumping performance, and the inner diameter must be increased in the structure of the inlet flow passage to reduce the flow resistance of the impeller inlet.

Seven references are cited:

US patent No. US7249939B2 r casting arrangement for magnetic drive pump, 2007, the present citation is applicable to a magnetically driven pump that bilaterally supports a stationary shaft and a rotating shaft, clearly indicates that the strength of the back cover of the magnetically driven pump is a matter of further concern, because the clearance between the outer rotor and the inner rotor is narrow, the high corrosion-resistant plastic material belongs to thermoplastic material, the strength of which is reduced along with the temperature, the prior art adds a second layer of reinforcing structure outside the corrosion-resistant material of the rear cover, the cited proposal adds a non-metal strip-shaped circular reinforcing piece between or outside the two layers of structures of the side cylindrical surface of the rear cover, so that the strength of the cylindrical part of the side of the rear cover is improved, the method is better than the conventional multilayer winding method in the circumferential direction of straight strip fibers, but this method can not effectively overcome the bending deformation of the cylindrical part when the shaft hole seat at the bottom of the back cover bears the radial force, the cited reference also indirectly confirms that the supporting force of the fixing shaft is also influenced by the strength of the cylindrical part of the rear cover.

Eight citations:

US6293772B1 patent of constant force for a magnetic-driven centrifugal pump in 2001, the citation clearly indicates that the strength of the plastic tripod and the rear cover of the magnetic-driven pump is a problem to be paid further attention, the front supporting tripod often affects the inlet flow passage of the impeller to reduce the pumping performance, the strength of the rear cover is used to resist the liquid pressure and provide the supporting of the fixed shaft, the proposal of the citation is that a disk-shaped metal reinforcing member is embedded between the first layer structure and the second layer structure at the bottom of the rear cover, so that the radial force borne by the cantilever fixed shaft can be uniformly transmitted to the cylindrical part of the rear cover, and the reinforcing member is shaped and comprises a part with a smaller diameter and an axial inner extension part for reinforcing the supporting and holding force of the fixed shaft, so that the strength of the fixed shaft can be enough to support the fixed shaft in a cantilever manner, thereby avoiding the supporting of the tripod and having enough supporting strength, however, the strength of the cylindrical portion on the side of the rear cover is not clearly described, and the problem that the fixed shaft is stressed to be prevented from being inclined after being strengthened is solved.

In view of the above references, the problems encountered with respect to the structure and strength of the stationary shaft in the magnetic drive pump of perfluoroplastic materials and cast iron casings with fluoroplastic linings can be divided into the following:

1. weak point of strength of fluoroplastic material itself

2. Rigidity requirement of fixed shaft support structure

3. Flow resistance problem of pump inlet channel

4. Cavitation erosion resistance problem (NPSHr) of impeller inlet flow passage

5. Strength of back cover, cylinder-containing part and bottom part

However, the respective solutions and solutions of these cited documents cannot simultaneously satisfy the requirement of a high rigidity fixed shaft for high temperature 200 ℃ liquid transportation, and the structural improvement of the magnetically driven pump of the present invention can simultaneously overcome the above problems.

Disclosure of Invention

The invention mainly aims to provide an improved structure of a magnetic drive pump, in particular to a fixed shaft strengthening structure for front and rear supports, because the parts of the magnetic drive pump are made of fluoroplastics or used as a lining, a rubber coating and the like, the fluoroplastics are named as PFA, ETFE and the like which have mechanical properties of high extensibility, high compression resistance and the like, such as a front cover, an impeller and a rear cover of a pump shell, the melting point temperature of the fluoroplastics exceeds more than 300 ℃, but the strength of the fluoroplastics is reduced along with the temperature rise, although the fluoroplastics are made of cast iron or stainless steel, the invention replaces the strength dependence on fluoroplastic structural parts by the structural rigidity of the pump shell, so that the pump can have high-reliability operation capability at the temperature of 200 ℃, wherein, the high-rigidity inlet support seat can provide the rigid supporting force required by the fixed shaft, and the high-rigidity support requirement of the fixed shaft is matched with the high-rigidity support seat, and, The volute flow passage and the impeller flow passage are integrally designed to obtain high-rigidity support of the fixed shaft and greatly reduce the flow resistance of the support seat to the pump inlet flow passage; the pump rear cover has the functions of sealing, no leakage, temperature resistance and pressure resistance and provides auxiliary support for one end of the fixed shaft;

the supporting seat is a cast iron or stainless steel pump shell integrated two-ribbed plate structure extending axially and internally, the ribbed plate radially extends from the inner surface of the pump inlet of the shell to the center of the circle, and is combined with two-ribbed plate 90-degree right-angle components at the center of the inner diameter, an arc cone taking the center of the circle as the center is formed at the joint from the inlet side, the axially inner side extends to the inner side of the pump shell, a shaft seat is arranged at the tail end of the pump shell, the ribbed plate is lengthened along with the axial extension of the cone and shrinks the width of the plate to the outer diameter of the shaft seat, the shaft seat penetrates through the hub hole of the impeller and the outer arc of the shaft seat and the hub of the impeller form a smooth curved surface, and the outer side;

the front side edge of the volute flow channel is in a volute structure, so that the axial position of the outlet center of the impeller flow channel is positioned at the inner side of the outlet flow channel center of the pump, and the sufficient flow length from the pump inlet to the impeller inlet is ensured, so that the adverse effect of flow field disturbance caused by the supporting seat on the impeller inlet is reduced;

the impeller flow passage structure adopts the design that the front cover has a small rear inclined angle, and the hub plate adopts the design of a front inclined curved surface to match with the shaft seat profile curved surface of the supporting seat, so that the inlet flow passage of the front edge of the blade of the impeller has a sufficient structural section area;

the fixed shaft is composed of a ceramic shaft with equal diameter, the front end of the fixed shaft is fixed by a shaft seat of a supporting seat, and a composite fixed shaft is a better scheme when the fixed shaft is used for a high-power pump; the composite fixed shaft is a high-rigidity shaft formed by compounding a metal shaft and a ceramic shaft sleeve, the metal shaft is directly connected with shaft seat metal of a supporting seat, high tension is applied to the ceramic shaft sleeve to form the high-rigidity fixed shaft, and the rear end of the fixed shaft is fixed by a shaft hole seat of a rear cover;

the back cover is a cup-shaped two-layer shell structure with a fluoroplastic lining and a fiber reinforced layer, the front flange is fixed on the front pump cover and the bracket to form a cylindrical cup-shaped cantilever structure, the bottom of the back cover is provided with a shaft hole seat without any through hole to ensure that the back cover does not leak, the flange part at the front end of the back cover is combined with the front pump cover and the flange of the bracket to prevent the leakage of corrosive liquid, a metal ring is arranged between the two layers of shells of the shaft hole seat to reduce the high-temperature deformation of fluoroplastics and provide stable support for a fixed shaft and a thrust bearing, and the cantilever structure of the back cover can assist the support rigidity of the fixed shaft;

the following is a description of the effects achieved by the present invention:

1, the melting point temperature of the fluoroplastic exceeds more than 300 ℃, the strength of the fluoroplastic is greatly reduced at 200 ℃, and the structural rigidity of the metal shell replaces the strength dependence on a fluoroplastic structural member, so that the pump can have high-reliability running capability at 200 ℃;

2, the structure of the shaft support seat is integrated with the front cover of the pump, and the fluoroplastic is coated to block corrosive liquid, so that the support rigidity of the fixed shaft is mostly from the support frame, and the shaft hole seat of the rear cover only has an auxiliary effect;

3, the metal structure of the front cover of the pump and the supporting frame are integrated into a whole and the axial length of the supporting frame is extended, so that the shaft fixing seat of the supporting frame extends into the opening of the impeller hub, and the flow resistance of the supporting frame at the inlet of the pump is greatly reduced;

4, improving the flow passage structure of the impeller and the inlet flow passage thereof, increasing the area of the inlet flow passage to reduce the inlet flow velocity and increase the cavitation erosion resistance (NPSHr), and matching the cross-sectional shape of the support frame with the flow line of the flow to reduce the interference of the support frame on the flow;

5, the function of the rear cover is only used for bearing the functions of sealing, no leakage, temperature resistance and pressure resistance; the structure of the rear cover comprises a first layer structure which is fluoroplastic and a second layer reinforcing structure, wherein the first layer structure is a cup-shaped fluoroplastic structure, the center of the disc-shaped bottom of the first layer structure is provided with a shaft hole seat which extends outwards and protrudes without a through hole, and the second layer structure is a thermal hardening resin fiber reinforcing structure which is used for reducing the deformation of the fluoroplastic at high temperature, bearing the liquid pressure to reduce the deformation and bearing the impact pressure caused by the flowing of a pipeline;

the structure improvement of the invention enables the magnetic drive pump with various power ranges to have high-reliability operation capability at the temperature of 200 ℃, and is suitable for simple fixed shaft structures and composite shaft structures.

Drawings

Fig. 1 (a): the cross-sectional view of the first embodiment of the present invention is a cross-sectional view of a fixed shaft structure with two-sided support.

FIG. 1 (B): the cross-sectional view of the second embodiment of the present invention is a cross-sectional view of a composite stationary shaft structure with bilateral support.

Fig. 2 (a): front view of the inlet of the first embodiment of the present invention.

Fig. 2 (B): front view of the inlet of the second embodiment of the present invention.

FIG. 3: front cover 3D rear view of the first embodiment of the invention.

Fig. 4 (a): the cross-sectional view of the inlet channel of the first embodiment of the present invention is shown.

Fig. 4 (B): the cross-sectional view of the inlet channel of the second embodiment of the present invention is shown.

FIG. 5: the cross-sectional view of the rear cover of the first embodiment of the present invention is shown.

FIG. 6: the first embodiment of the present invention is schematically illustrated in terms of the bearing force and moment of the fixed shaft.

FIG. 7: the composite stationary shaft of the second embodiment of the present invention is schematically illustrated in terms of bearing force and moment.

Detailed Description

The invention is illustrated in detail in the drawings as follows:

the first embodiment: magnetically driven pumps with bilateral support fixed shaft structure, FIG. 1 (A);

referring to fig. 1(a), the magnetic driving pump of the present embodiment is a fixed shaft structure supported at both sides, and the main components include: front cover 4, support frame 43, impeller 5, back lid 41, inner rotor 7, outer rotor 92, fixed axle 3 and bracket 91, wherein:

the front cover 4 is made of cast iron or stainless steel, and is provided with a pump inlet 44, a pump outlet 45 and a scroll runner 47, the interior of the front cover 4 is used for accommodating the impeller 5, an inlet thrust collar 46 is arranged at the pump inlet 44 on the inner side of the front cover 4 of the pump and is used for being coupled with an impeller thrust bearing 53 on the inlet side of the impeller 5 to form an axial thrust bearing; a lining 4a is installed on the liquid-contacting side inside the front cover 4 to isolate the corrosive liquid, an integrated supporting frame 43 is installed inside the pump inlet 44, and the back flange 42 (matching with figure 3) on the back side is used for installing the flange 411 and the strengthening plate 411a of the pump back cover 41 and combining with the flange 911 of the bracket 91 to prevent the leakage of the corrosive liquid;

the supporting frame 43 is a structure of two rib plates 431 extending from the inner diameter of the pump inlet 44 of the front cover 4 to the axial inner side, the rib plates 431 extend radially from the inner diameter of the pump inlet 44 of the front cover 4 to the center of the circle, and are combined into two 90-degree right-angle rib plate members at the center of the inner diameter, and are combined into an arc cone 432 taking the center of the circle at the inlet side, the arc cone 432 extends to the inner side of the pump shell from the axial inner side, and the tail end of the arc cone 432 is provided with a shaft seat 433, the shaft hole 433a of which is used for supporting one end of the; the rib 431 also lengthens along the axial extension of the cone 432 and contracts the width of the plate to the outer diameter of the shaft seat 433; the shaft seat 433 passes through the impeller hub hole 54 and its outer arc and the flow passage hub surface 515 of the impeller 5 form a smooth curved surface, the outer side of the supporting frame 43 is completely covered with the rubber coating 43a by fluoroplastic and is integrated with the pump casing lining 4 a;

the impeller 5 is made of fluoroplastic and installed inside the front cover 4 of the pump, the center of the impeller hub 52 has an impeller hub opening 54, the supporting frame 43 can axially pass through one end for supporting the fixed shaft 3, the back side of the impeller hub 52 is used for combining with the axial extension 76 of the inner rotor 7, so that the impeller 5 and the inner rotor 7 form a whole or the impeller 5 and the inner rotor 7 are embedded into each other to form a whole, if necessary, a disk-shaped strengthening member 56 (matching with fig. 6) is installed inside the impeller hub 52 to transmit high-power shaft work to the conveying fluid, and the strengthening member 56 and the yoke 72 of the inner rotor 7 can also form a whole;

the back cover 41 is a cup-shaped two-layer shell structure with fluoroplastic back cover liner 41a and reinforced layer 41b, the bottom has shaft hole seat 413 and no through hole to ensure no leakage of the back cover 41, the reinforced plate 411a of the front flange 411 is used to combine the flange 42 (matching with fig. 3) of the back cover 4 of the pump and the flange 911 of the bracket 91 to form a cylindrical cup-shaped cantilever structure to prevent leakage of corrosive liquid, and the reinforced plate 411a is used to ensure the structural strength and locking effect; a cylindrical part 412 (fig. 5) on the side of the rear cover 41 passes through the inner diameter space of the outer rotor 92, and an inner chamber space 415 of the rear cover 41 is used for installing the inner rotor 7; the back cover 41 is used to separate the two parts and keep a certain gap between them to ensure that the corrosion liquid will not leak due to abrasion; the shaft hole seat 413 is arranged at the center of the bottom of the rear cover, axially extends to the outer side of the inner space of the outer rotor 92, and is used for supporting one end of the fixed shaft 3, the outer edge of the shaft hole is provided with a thrust ring 414 which is used for being coupled with a bearing 79 of the inner rotor 7 to form an axial thrust bearing, the middle of the two-layer shell outside the shaft hole of the shaft hole seat 413 is provided with a metal ring 417 so as to reduce the deformation of the fluoroplastic rear cover lining 41a at high temperature, so as to provide stable support for the fixed shaft 3 and the thrust bearing 414, and the rear cover 41 can assist the support rigidity of;

the inner rotor 7 is a ring structure composed of inner magnets 71, a yoke 72 and an axial extension 76, the inner magnets 71 are arranged on the outer ring surface of the yoke 72, and are coated with corrosion-resistant engineering plastics to form a ring-shaped rotor rubber coating 74 with zero leakage seam, a bearing 79 is arranged in the middle hole of the inner rotor 7, and the axial extension 76 of the inner rotor 7 is used for being combined with the impeller hub 52, so that the inner rotor 7 and the impeller 5 are integrated into a whole or the inner rotor 7 and the impeller 5 are embedded into a whole;

the outer rotor 92 is a ring-shaped cup structure composed of an outer magnet 93, a yoke 92b and a connecting seat 92a, the connecting seat 92a is fixedly combined with the axis 95 of the driving motor, a plurality of outer magnets 93 are arranged on the inner ring surface of the yoke 92b, the outer rotor 92 is driven by the axis 95 of the driving motor to rotate, the inner magnet 71 of the inner rotor 7 and the outer magnet 93 of the outer rotor 92 are positioned at the same position across the rear cover 41 and are arranged in a polarity attraction manner in a radial opposite manner, when the outer rotor 92 rotates, the outer magnet 93 attracts the inner magnet 71 to drive the inner rotor 7 to rotate;

the fixed shaft 3 is a bilateral support structure and is made of corrosion-resistant and wear-resistant ceramic materials, the front end of the fixed shaft is supported by a support frame 43 of the front cover 4, the rear end of the fixed shaft is supported and fixed by a shaft hole seat 413 of the rear cover 41, the middle part of the fixed shaft 3 is coupled and rotated with a bearing 79 of the inner rotor 7, the length of the middle part of the fixed shaft meets the length of the bearing 79 to bear the compound force borne by the inner rotor 7, an axial free movement space of the inner rotor 7 is reserved, a rib plate 431 and a shaft seat 433 of the support frame 43 provide high-rigidity support for the fixed shaft 3 and provide a shaft holding length L at the same time, and the problem that the strength;

the bracket 91 is a ring structure with two flanges; the flange on one end is used to lock and fix on the flange on the end face of the motor (not shown), the flange 911 on the other end is used to combine with the reinforced plate 411a of the flange part 411 of the back cover 41 to prevent the leakage of the corrosive liquid, and the flange strong back plate 411a of the flange 411 is used to ensure the structural strength and locking effect;

when the pump is running, the fluid flows in from the pump inlet, such as the flow direction 6, and flows to the inlet of the impeller 5, such as the flow direction 61, and becomes a fluid with pressure after flowing through the flow channel of the impeller 5, such as the flow direction 62, and is output from the pump outlet 45, meanwhile, a part of the fluid, such as the flow direction 63, enters the chamber space 415 of the back cover 41 through the back side of the impeller 5, and flows to the bottom of the back cover through the gap between the outer side of the rotor and the inner diameter of the back cover, such as the flow direction 64, and then flows through the gap between the fixed shaft 3 and the bearing 79, and finally flows through the impeller hub hole 54, such as the flow direction 65, and returns to the impeller inlet, and the circulation flow of the fluid is used for providing the lubrication of the;

second embodiment: a magnetically driven pump of double-sided supported composite stationary shaft structure for high temperature, high power applications, fig. 1 (B);

referring to fig. 1(B), the magnetic driving pump of the present embodiment is a fixed shaft structure supported at both sides, and the main components include: front cover 4, support frame 431, impeller 5, back cover 41, inner rotor 7, outer rotor 92, compound fixed axle 3a and bracket 91, wherein:

the front cover 4 is made of cast iron or stainless steel, and is provided with a pump inlet 44, a pump outlet 45 and a scroll flow passage 47, and the inner space of the front cover is used for accommodating the impeller 5; an inlet thrust collar 46 is arranged at the position of a pump inlet 44 on the inner side of the pump front cover 4 and is used for being coupled with an impeller thrust bearing 53 on the inlet side of the impeller 5 to form an axial thrust bearing; the liquid-receiving side inside the front cover 4 is provided with a lining 4a to isolate the corrosive liquid; an integral support bracket 43 in the inner diameter space of the pump inlet 44; a rear flange 42 (see fig. 3) on the back side thereof for mounting the flange 411 and the reinforcing plate 411a of the pump front cover 4 and for engaging with a flange 911 of the bracket 91 for preventing leakage of the corrosive liquid;

the supporting frame 43 is a structure of two ribs 431 extending axially inward of the inner diameter of the pump inlet 44 of the front cover 4; the rib 431 extends radially from the inner surface of the pump inlet 44 of the front cover 4 to the center of the circle, and is combined with two 90-degree right-angle rib members at the inner diameter center of the circle, and is combined with an arc cone 432 taking the center of the circle as the center from the inlet side, the arc cone 432 extends to the inner side of the pump shell from the axial inner side, and the tail end of the arc cone 432 is provided with a shaft seat 433, and a shaft hole 433a (matched with the figure 3) of the shaft seat is used for supporting one end of a fixed shaft 3 a; the rib 431 also lengthens along the axial extension of the cone 432 and contracts the width of the plate to the outer diameter of the shaft seat 433; the shaft seat 433 passes through the impeller hub hole 54 and its outer arc and the flow passage hub surface 515 of the impeller 5 form a smooth curved surface, the outer side of the supporting frame 43 is completely covered with the rubber coating 43a by fluoroplastic and is integrated with the pump casing lining 4 a; the inside of the shaft hole 433a (matching with fig. 3) is not covered with rubber, and the center thereof is provided with a thread hole 433b for tightly locking the thread part at one end of the metal shaft 32 of the composite shaft 3a, and the inner diameter of the shaft hole 433a is loosely matched with the outer diameter of the metal shaft 32; the end surface of the shaft seat 433 is divided into two annular surfaces, the pressing surface 435 and the sealing surface 43c are tightly pressed and attached to the end surface of the ceramic shaft sleeve 33 to ensure the supporting rigidity of the fixed shaft 3a, and the rubber coating 43a of the sealing surface 43c is ensured to have enough compression amount and sealing effectiveness to prevent the leakage of corrosive liquid;

the impeller 5 is installed inside the pump front cover 4, the supporting frame 43 can axially pass through the impeller hub opening 54 to support one end of the fixed shaft 3a, the impeller hub 52 is used to combine with the axial extension 76 of the inner rotor 7, so that the impeller 5 and the inner rotor 7 are integrated into a whole or the impeller 5 and the inner rotor 7 are embedded into a whole, if necessary, the impeller hub 52 is internally provided with a disk-shaped strengthening member 56 (matching with fig. 6) to transmit high-power shaft work to the conveying fluid, and the strengthening member 56 can also be integrated with the yoke 72 or the light member 73 of the inner rotor 7;

the back cover 41 is a cup-shaped two-layer shell structure with a back cover lining 41a and a reinforced layer 41b, the bottom has a shaft hole seat 413 without any through hole to ensure that the back cover 41 does not leak, the reinforced plate 411a of the flange part 411 at the front end is combined with the back flange 42 of the back side of the pump front cover 4 and the flange 911 of the bracket 91 to form a cylindrical cup-shaped cantilever structure for preventing the leakage of the corrosive liquid, and the reinforced plate 411a is used for ensuring the structural strength and the locking effect; a cylindrical part 412 (in fig. 5) on the side of the rear cover 41 penetrates through the inner diameter space of the outer rotor 92, and an inner chamber space 415 of the rear cover 41 is used for installing the inner rotor 7, and the rear cover is used for separating the inner rotor and the outer rotor and keeping a certain gap therebetween so as to ensure that the rear cover 41 cannot be worn and damaged to cause corrosion liquid leakage; the shaft hole seat 413 is arranged at the center of the bottom of the rear cover and extends axially outside the inner space of the outer rotor 92, the outer edge of the shaft hole is provided with a thrust collar 414 for coupling with the bearing 79 of the inner rotor 7 to form an axial thrust bearing, the middle of the two-layer shell outside the shaft hole of the shaft hole seat 413 is provided with a metal ring 417 to reduce the deformation of the fluoroplastic rear cover lining 41a at high temperature so as to provide stable support for the fixed shaft 3 and the thrust bearing 414, and the rear cover 41 can assist the support rigidity of the fixed shaft 3 a;

the inner rotor 7 is a ring structure composed of inner magnets 71, a yoke 72, a light weight component 73 and an axial extension 76, the plurality of inner magnets 71 are arranged on the outer ring surface of the yoke 72, and are coated by corrosion-resistant engineering plastics to form a ring-shaped rotor rubber coating 74 with zero leakage seam, a bearing 79 is arranged in the middle hole of the inner rotor 7, and the axial extension 76 of the inner rotor 7 is used for being combined with the impeller hub 52, so that the inner rotor 7 and the impeller 5 are integrated into a whole or the inner rotor 7 and the impeller 5 are embedded into a whole; the inner rotor for high power use often has a problem of being too heavy in weight, and the lightweight member 73 made of light metal or reinforcing fiber becomes one of the options for weight reduction; if necessary, a disk-shaped reinforcing member 56 (see fig. 6) is installed inside the impeller hub 52 to transmit high-power shaft work to the transportation fluid, and the reinforcing member 56 may be integrated with the yoke 72 or the light-weight member 73 of the inner rotor 7;

the outer rotor 92 is a ring-shaped cup structure composed of an outer magnet 93, a yoke 92b and a connecting seat 92a, the connecting seat 92a is fixedly combined with the axis 95 of the driving motor, a plurality of outer magnets 93 are arranged on the inner ring surface of the yoke 92b, the outer rotor 92 is driven by the axis 95 of the driving motor to rotate, the inner magnet 71 of the inner rotor 7 and the outer magnet 93 of the outer rotor 92 are positioned at the same axial position through the rear cover 41 and are arranged in a polarity attraction manner in a radial opposite manner, and when the outer rotor 92 rotates, the outer magnets 93 attract the inner magnets 71 to drive the inner rotor 7 to rotate;

the composite fixed shaft 3a is a bilateral support structure, the front end of the composite fixed shaft is supported by the support frame 43 of the front cover 4 and the rear end of the composite fixed shaft is supported and fixed by the shaft hole seat 413 of the rear cover 41, the middle part of the composite fixed shaft 3 is coupled with the bearing 79 of the inner rotor 7 to rotate, the length of the middle part of the composite fixed shaft meets the length of the bearing 79 to bear the composite force borne by the inner rotor 7, the axial free movement space of the inner rotor 7 is reserved, the rib plate 431 and the shaft seat 433 of the metal support frame 43 provide high-rigidity support for the fixed shaft 3a, and the problem that the strength of a plastic material is;

the composite fixed shaft 3a is composed of a corrosion-resistant and wear-resistant ceramic shaft sleeve 33, a metal shaft 32 and a sealing nut 323; the metal shaft 32 passes through the center hole of the ceramic shaft sleeve 33, is tightly locked at the screw thread hole 433b at the center of the shaft seat 433 of the supporting frame 43 by the screw thread part, and is tightly pressed on the end surface of the ceramic shaft sleeve by the screw nut 321 (matching with figure 7) at the screw thread part at the other end;

the front end face of the ceramic bushing 33 is pressed tightly against the pressing face 435 and the sealing face 43c of the end face of the shaft seat 433 of the supporting frame 43, and the rear end face of the ceramic bushing 33 is also pressed tightly by the locking nut, so as to ensure the supporting rigidity of the fixing shaft 3a and ensure the encapsulation 43a of the sealing face 43c with sufficient compression amount and sealing effectiveness; the sealing nut 323 is a cup-shaped cylindrical metal part, and is covered with plastic encapsulation 322 (matching with fig. 7), the non-open end of the sealing nut 323 can be locked on the thread at the tail end of the metal shaft 32 by a tool to completely seal the composite fixed shaft 3a, the end surface of the opening part can be tightly pressed with the rear end surface of the ceramic shaft sleeve 33 to achieve the sealing and corrosion-resistant functions, so as to form a high-rigidity composite fixed shaft 3a, and the cylindrical outer diameter of the sealing nut 323 can be supported and fixed by the shaft hole seat 413 of the rear cover 41;

the bracket 91 is a ring structure with two flanges; the flange on one end is used to lock and fix on the flange on the end face of the motor (not shown), the flange 911 on the other end is used to combine the reinforced plate 411a of the flange part 411 of the back cover 41 and the flange 42 on the back side of the pump front cover 4 to prevent the leakage of the corrosive liquid, and the reinforced plate 411a is used to ensure the structure strength and the locking effect;

when the pump is running, the fluid flows in from the pump inlet, such as the flow direction 6, and flows to the inlet of the impeller 5, such as the flow direction 6, and becomes a fluid with pressure after flowing through the flow channel of the impeller 5, such as the flow direction 62, and is output from the pump outlet 45, and at the same time, a part of the fluid, such as the flow direction 63, enters the chamber space 415 of the back cover 41 through the back side of the impeller 5, and flows to the bottom of the back cover through the gap between the outer side of the rotor and the inner diameter of the back cover, such as the flow direction 64, and then flows through the gap between the fixed shaft 3 and the bearing 79, and finally flows through the impeller hub hole 54, such as the flow direction 65, and returns to the impeller inlet, and the circulation flow of the fluid is used for providing.

Referring to fig. 2(a) and 2(B), which are front views of the supporting frame 43, the supporting frame 43 is composed of two 90-degree ribs 431 extending from the inner surface of the pump inlet 44 toward the center of the circle, and a cone 432 with a shaft seat 433 at the tail end thereof located at the center of the inner diameter, which form a cantilever structure extending axially through the impeller hub hole 54 and integrated with the front cover 4, and after the cross sections of the ribs 431 and the cone 432 plus the thickness of the rubber coating 43a, the sum of these sectional areas is the sectional area of the support frame, i.e. the blocking area of the inlet flow passage section, the rest of the sectional areas of the inlet flow passage are the flow areas, the larger the blocking area is, the smaller the effective flow area is, the flow velocity of the fluid will be in a linear inverse relationship with the flow area, the flow resistance is increased in direct proportion with the quadratic linearity of the flow velocity, namely the resistance is greatly increased in inverse proportion of the quadratic degree when the effective flow area is smaller; the inner diameter of the inlet 44 is not particularly increased in either of the following two embodiments, fig. 2(a) is a low-power small-diameter specification of the first embodiment, in which the blocking area is less than about 28% of the inlet cross-sectional area, and fig. 2(B) is a high-power large-diameter specification of the second embodiment, in which the blocking area is less than about 15% of the inlet cross-sectional area; the height of the plugging area ratio is also related to the manufacturing method, for example, the thickness of the cast iron or stainless steel ribbed plate cast by a sand mold is at least 6mm, and the thickness of the rubber coating is more than 3mm on one side, so that the total thickness of the ribbed plate is at least 12mm, and compared with the low-power pump with the inlet caliber of 50mm, the plugging area ratio is naturally relatively increased, and when the conventional cast iron tripod is also used with the inlet caliber of 50mm, the plugging area ratio can exceed 40% after rubber coating, which is very unfavorable for reducing the flow resistance, and is also the reason that the creation needs to create a support frame structure; the invented support frame structure overcomes the blocking area, and also properly matches the cross-sectional area of the support frame to increase the inner diameter of the pump inlet 44, and increases 12% by taking the first embodiment as an example, so as to ensure the flow resistance in a reasonable range without causing a significant influence on the inlet caliber of the impeller; on the contrary, the conventional tripod structure may have an increased inlet diameter ratio of up to 20%, which has a great influence on the inlet diameter of the impeller, and the expansion angle of the cylindrical surface of the inner diameter of the pump inlet 44 is also greatly increased, i.e. the pump performance is directly affected.

Referring to fig. 3, which is a 3D view of the front cover 4 of the first embodiment, the front cover 4 and the supporting frame 43 are described in detail, the front cover 4 is provided with a pump inlet 44, an outlet 45 and a scroll flow passage 47 for accommodating the impeller 5 (fig. 1(a)), the liquid receiving side of the front cover 4 is provided with a lining 4a for isolating corrosive liquid, the supporting frame 43 is integrally provided inside the pump inlet 44, and the rear flange 42 at the back side thereof is provided with a bracket 91 (fig. 1(a)) and the rear cover 4 (fig. 1(a)) and a reinforcing plate 411a (fig. 1(a)) for preventing the leakage of corrosive liquid; the supporting frame 43 is a structure of two 90-degree ribs 431 extending from the inner side of the pump inlet 44 of the front cover 4 in the axial direction, the ribs 431 extend radially from the inner side of the pump inlet 44 of the cast iron front cover 4 toward the center of the circle, and are combined with the center of the inner diameter to form two 90-degree rib right-angle members, and an arc cone 432 (matching with fig. 1(a)) centering on the center of the circle is formed at the combination position from the inlet side, a shaft seat 433 is installed at the tail end, the shaft hole 433a thereof is used for supporting one end of the fixed shaft 3 (matching with fig. 1(a)), and the inner hole surface of the shaft hole 433a shows that the fixed shaft 3 (matching with fig. 1(a)) has symmetrical and parallel cutting edges to; the rib 431 is also lengthened along the axial extension of the cone 432 and contracts the width of the plate to the outer diameter of the shaft seat 433, and the outer side of the support 43 is completely covered with the rubber 43a by fluoroplastic and is integrated with the pump casing liner 4 a.

Referring to fig. 4(a), this figure shows an impeller 5 and an inner rotor 7 of the first embodiment, the impeller 5 is installed inside a pump front cover 4 (matching fig. 1(a)), a support frame 43 (dashed line part) can axially pass through an impeller hub opening 54, the inner rotor 7 is a ring structure formed by an inner magnet 71, a yoke 72 and an axial extension 76, and is coated by fluoroplastics to form a zero-leakage annular rotor coating 74, a bearing 79 is installed in a middle hole of the inner rotor 7, the impeller hub 52 is used for combining with the axial extension 76 of the inner rotor 7, so that the impeller 5 and the inner rotor 7 are integrated or the two are embedded into one; referring to fig. 1(a), the front side scroll structure of scroll flow channel 47 positions the flow channel center line 513 of impeller 5 inside the pump outlet center 451, so that the flow direction 6 of the inlet of impeller 5 has a longer flow length.

Referring to fig. 4(a), the impeller 5 is a centrifugal structure, the front cover 514 is designed to be connected to the vertical axis, and the curved surface 514a near the front edge 511 of the impeller inlet has a proper curvature radius; the hub surface 515 adopts a concave curved surface 515a design near the front edge 511 to match with the curved surface 432a of the cone 432 of the support seat, so that the front edge 511 of the blade 51 of the impeller has a sufficient flow area and a better curvature radius in the flow direction 61 is ensured, thereby reducing the adverse effect of the flow field disturbance caused by the support frame 43 on the inlet of the impeller;

the fluid can flow smoothly through the center line 513 of the flow channel of the impeller 5 from the flow direction 6 and the flow direction 61 of the pump inlet 44, the inner diameter cylindrical surface 44a of the pump inlet 44, the front cover inlet curved surface 514a and the flow channel front cover surface 514 form a smooth curved surface, the diameter of the front end of the cone 432 is equal to the thickness of the rib plate, the diameter is increased to the outer diameter of the shaft seat 433 in a conical curved surface mode after extending axially to the impeller inlet, the curved surface 432a of the cone 432 and the inner concave curved surface 515a of the flow channel hub surface 515 of the impeller 5 form a smooth curved surface, after the fluid flows in from the pump inlet 44 along the axial flow direction 6, the fluid is converted into radial flow through the flow direction 61 and the center flow line 513, in the process, the space of the inner diameter of the pump inlet is only the thickness of the rib plate 431 is the blocking area of the flow channel, the very smooth change of the flow channel cross-section can be obtained, and the flow direction 61 obtains a preferred radius of curvature, among which the main factors influencing the flow are the thickness of the ribs 431 at an angle of 90 degrees to each other and the change in diameter of the cone 432 extending axially from the nose 434, i.e. the flow direction 6 of the fluid flowing into the pump inlet 44 increases in flow velocity and has the lowest turbulence occurring after passing over the curved leading edge 431a (dashed line portion) of the ribs 431 (dashed line portion), since the flow direction 6 has a longer flow length, the fluid is rectified to flow smoothly and reduce the flow resistance after passing through the rib 431 (dotted line portion), the curved rear edge 431b (dotted line portion) of the rib 431 (dotted line portion) flows out to be ready to flow into the vane front edge 511, a space flow field is formed between the vane leading edge 511 and the arc trailing edge 431b (dotted line portion) of the rib 431 (dotted line portion), and the flow direction 61 has a better curvature radius influence, so that the flow field interference can be greatly reduced and the low flow resistance can be ensured;

a lower NPSHr value indicates better cavitation erosion resistance, but the key is that the impeller inlet has a lower flow velocity, and the fluid has sufficient cross-sectional area to maintain the lower flow velocity when passing the leading edge 511 of the blade 51, and whether the blade angle is the same as or close to the fluid angle, which is a design problem and is not within the scope of this creation, but the presence of sufficient cross-sectional area near the leading edge 511 is the key point of this creation; although the front cover surface 514 adopts the design of the angle of the approach to the vertical axis, the curved surface 514a near the front edge 511 adopts the proper curvature radius to keep the reasonable flow velocity of the fluid, and the curved surface 432a of the cone 432 of the supporting seat is designed by adopting the concave curved surface 515a near the hub surface 515 close to the front edge 511 to match with the curved surface 432a of the cone 432 of the supporting seat, so that when the fluid flows along the surface of the cone 432 and is changed from the axial direction to the radial direction, the fluid can have the better curvature radius in the flow direction 61 without excessively increasing the flow velocity locally, and the support 43 has the rectification effect of the longer rib 431, so that the impeller 5 has the lower NPSHr value;

referring to fig. 4(B), the impeller 5 and the inner rotor 7 of the second embodiment are illustrated, the inlet flow passage and the blade flow passage are described in detail in fig. 4(a), and the advantages of such design will be further described in fig. 4(B), in practical use, the outer diameter of the impeller 5 needs to be trimmed to adjust the pump output lift to meet the requirement of the process or the pipeline, and fluoroplastic forming is not easy for manufacturers to have very many specifications for users, and the outer diameter of the impeller 5 can meet the requirement of the customers, and the trimming width sometimes exceeds the outer diameter D₂20% or more, and fig. 4(B) is a high-power specification of a large flow rate, and the inlet diameter D of the impeller 5 is set to₁And the outer diameter D of the outlet₂Ratio D₁/D₂Is very different from the ratio of the impeller 5 in fig. 4(a), fig. 4(a) is a small power specification with small flow and high lift, when the outer diameter of the impeller 5 is car repaired, the rear edge 512 of the blade 51 of the impeller 5 and the front cover of the impeller 5 are reduced in outer diameter due to the car repair, that is, D is after the car repair₁/D₂The larger the ratio is, the lower the pumping efficiency is, because the working conditions of the streamline 513 are further away from the original optimum design, and conversely, if the structure of the supporting frame 43 adopts a conventional tripod, the larger the pump inlet 44 and the impeller inlet diameter D is adopted₁Although the effect of reducing the inlet flow velocity and the flow resistance can be obtained, the vehicle will be repaired D₁/D₂The ratio of (A) to (B) is increased to reduce the outer diameter D of the wheel after turning₂Range and efficiency of (D) after vehicle repair₁/D₂The present inventor explains the design principle of the support frame 43 to reduce the flow resistance and ensure the pumping efficiency particularly by using these two figures, and the present inventor has an impeller inlet diameter D₁The enlarged range is within 12%, so that reasonable performance and efficiency of the pump can be ensured.

Referring to fig. 5, the back cover 41 is a cup-shaped two-layer housing structure having a back cover liner 41a and a reinforcing layer 41b, the bottom has a shaft hole seat 413 without any through hole to ensure that the back cover 41 will not leak, the reinforcing plate 411a of the flange 411 at the front end is combined with the back flange 42 (in fig. 3) at the back side of the pump front cover 4 (in fig. 1(a)) and the flange 911 (in fig. 1(a)) of the bracket 91 to form a cylindrical cup-shaped cantilever structure to prevent the leakage of the corrosive liquid, and the reinforcing plate 411a is used to ensure the structural strength and locking effect; the rear cover 41 is in a cantilever structure when bearing radial force and is completely supported by the front end flange 411 and the auxiliary structure thereof; the strength of the rear cover 41 completely depends on the support of the reinforcing layer 41b, including the radial force borne by the fixing shaft 3 (matching with fig. 1(a)) and the hydraulic pressure of the chamber space 415, the cylindrical part 412 of the rear cover 41 has the largest deformation when bearing the pressure, the conventional technology adopts a straight fiber circumferential direction multilayer winding mode in the cylindrical part 412 of the reinforcing layer 41b to reduce the expansion deformation generated by the pressure, but this mode cannot effectively overcome the bending deformation of the cylindrical part 412 when the shaft hole seat 413 at the bottom of the rear cover 41 bears the radial force, although the conventional technology adopts high temperature resistant plastics to combine fibers, the effect is still limited by the strength of the plastic material, the above description is particularly directed at high temperature and high pressure, the requirement of high durability under 200 ℃ and 16bar is not suitable for the requirement of general use; the back cover 41 internal chamber space 415 is used to mount the inner rotor 7 and isolate the outer rotor 92 (fig. 1(a)) from the delivery fluid pressure; the shaft hole seat 413 is disposed at the center of the bottom of the rear cover and has a central shaft hole 413a protruding axially outward, the outer edge of the shaft hole 413a is provided with a thrust collar 414 for coupling with the bearing 79 of the inner rotor 7 to form an axial thrust bearing, and a metal ring 417 is disposed between the fluoroplastic rear cover liner 41a and the reinforcing layer 41b of the shaft hole 413a and extends into the annular groove 413b for reducing the deformation of the fluoroplastic rear cover liner 41a at high temperature and providing auxiliary support for the fixed shaft 3 (matching with fig. 1(a)) and the thrust collar 414.

Referring to fig. 6, to explain the multiple load forces and torque of the dual-side supported stationary shaft 3 in detail, the stationary shaft 3 is made of corrosion-resistant and wear-resistant ceramic material, the front end of which is supported by the supporting frame 43 of the fluoroplastic rubber 43a, and the rear end of which is supported and fixed by the shaft hole seat 413 (in fig. 1 a) of the rear cover 41 (in fig. 1 a).

Referring to fig. 6, the supporting frame 43 is a structure of two 90-degree ribs 431 extending axially inward from the inner diameter of the pump inlet 44 of the front cover 4, the ribs 431 radially extend from the inner surface of the pump inlet 44 of the cast iron front cover 4 to the center of the circle, and are combined with the center of the inner diameter to form two 90-degree rib right-angle members, and are combined with an arc cone 432 centered on the center of the circle at the inlet side, and the tail end of the arc cone is provided with a shaft seat 433, and a shaft hole 433a (matching with fig. 3) of the shaft seat is used for supporting one end of the fixed shaft 3; the rib 431 is also lengthened along the axial extension of the cone 432, the width of the plate is contracted to the outer diameter of the shaft seat 433, the outer side of the support 43 is completely covered with the rubber coating 43a by the fluoroplastic and is integrated with the pump shell lining 4a, because the fluoroplastic has good compression resistance, the support can bear a high proportion of compression amount and is not damaged by fatigue, when the fixed shaft 3 is installed on the shaft seat 433, the fixed shaft 3 has proper compression amount and has proper holding length L to reduce the influence of the deformation amount of the lining rubber coating 43a of the shaft hole 433a, when the fixed shaft 3 bears radial force and moment, the fixed shaft 3 is firstly applied on the rubber coating lining 43a of the shaft hole 433a (matching with figure 3), because the deformation amount of the rubber coating 43a causes the primary deformation and displacement of the fixed shaft 3, therefore, the enough compression amount and holding length L during installation can easily transmit the stress to the support 43, the holding length L is at least 80% of the shaft diameter to reduce the deformation and displacement of the fluoroplastic lining 43a caused by the force, and the support frame 43 will be deformed and displaced secondarily by the force and torque transmitted from the shaft seat 433.

Referring to fig. 6, the middle portion of the fixed shaft 3 is coupled with a bearing 79 for supporting the rotation of the inner rotor 7 and has a length satisfying the length of the bearing 79; the fixed shaft 3 and its supporting structure are subjected to multiple load forces, including gravity W, centrifugal force X, side force P and torque of each applied force, wherein the gravity W is the force generated by the weight of the rotor, the centrifugal force X is the eccentric centrifugal force caused by the clearance of the bearing 79 in the center of mass of the rotor, the side force P is the force applied to the impeller 5 caused by the uneven fluid pressure in the scroll flow channel 47 of the front cover 4 of the pump, and the applied force directions of the two are changed in the radial direction according to the operating conditions.

Referring to fig. 6, when multiple load forces are applied to the stationary shaft 3, the moment generated by the force arm is also generated, taking the shaft seat 433 causing the preliminary deformation as an example, the reference position of the force arm is based on the center line B, the gravity moment is the gravity W multiplied by the force arm WL, the centrifugal moment is the centrifugal force X multiplied by the force arm XL, the lateral moment is the lateral force P multiplied by the force arm PL, the resultant force and the moment are the resultant force and the torque applied to the stationary shaft end, the eccentric centrifugal force X caused by the abrasion of the bearing 79 is the variable load source with the maximum structural rigidity of the stationary shaft 3, the eccentric centrifugal force X becomes larger as the abrasion amount is higher, the longest force arm XL is formed from the center of the bearing 79 to the center B of the shaft seat 433, the shortest force arm is the lateral force P caused by the uneven fluid pressure applied to the impeller, and the lateral force P causes the continuous deformation of the inner rotor 7, the secondary deformation and displacement occur on the supporting frame 43, based on the center line a of the center reference point of the supporting frame, the resultant force of the gravity W, the centrifugal force X and the lateral force P is the resultant force applied to the axle seat 433 and is also equal to the resultant force borne by the supporting frame 43, since the supporting frame 43 is a cantilever structure, the moment borne by the supporting frame is more important, the resultant force of the axle seat 433 multiplied by the moment arm AB is the moment value, and most of the forces and moments are borne by the supporting frame 43 of the fixed axle 3.

Referring to fig. 6, since the strength of the corrosion-resistant plastic rear cover 41 (in conjunction with fig. 1(a)) is reduced due to the temperature rise, and the pressure rise also has a deformation problem, if the center line C of the center reference point of the rear cover shaft hole seat 413 is taken as the reference point, a part of the resultant force applied to the shaft seat 433 is applied to the shaft hole seat 413, the moment applied thereto must be considered, the length of the moment arm is the distance BC from the center line B to the center line C, that is, the resultant force of the shaft seat 433 is multiplied by the moment arm BC to be a moment value, since the length of the moment arm BC is greater than AB, and the strength of the rear cover 41 is much lower than that of the metal support frame 43, therefore, most of the force and moment applied to the fixing shaft 3 will be borne by the support frame 43.

Referring to fig. 6 and fig. 2(a) and 2(B), the supporting frame 43 is a 90-degree right-angle member formed by combining two ribs, but the symmetrical structure of the conventional tripod has good structural strength but the flow channel area of the right-angle member cannot meet the requirement in the present invention, the flow channel area of the right-angle member in the present invention can meet the requirement as shown in fig. 4(a), and the strength of the right-angle member can meet the required design principle as follows:

when the shaft seat 433 bears the radial force and moment of the fixed shaft 3, the force and moment are transmitted to the rib 431 through the cone 432 and then transmitted to the front cover 4 at the inner diameter of the pump inlet 44 through the rib 431; the radial force applied to the shaft seat 433 can be analyzed into two components which are perpendicular to each other and have different magnitudes, the two rib plates 431 with 90 degrees can bear the two component forces at the same time, and the two rib plates 431 with 90 degrees can bear the moment at the same time more effectively; the key to the structural strength of the 90 degree rib 431 is that the plate thickness has sufficient thickness and width BL, and the rib 431 and the shaft seat 433 are combined to have sufficient combination length, which is the length of the conical curved surface 432a, and in addition, the rib 431 has sufficient width RL when radially extending from the inner surface of the pump inlet 44 of the front cover 4 to the center of the circle, that is, the conical curved surface 432a not only can provide smooth flow of fluid but also can bear and transmit force and moment, so that the support 43 structure of the present invention can simultaneously satisfy the function of reducing flow resistance, and can also achieve the required support rigidity.

Please refer to fig. 7, which illustrates the multiple load forces and torques thereof for supporting the stationary shaft 3a at two sides, wherein the front end is supported by the supporting frame 43 of the front cover 4, the rear end is supported and fixed by the shaft hole seat 413 (matching fig. 1(B)) of the rear cover 41, the middle part of the composite stationary shaft 3 is coupled with the bearing 79 of the inner rotor 7 for rotation, and the length of the middle part is sufficient for the bearing 79 to bear the composite force applied to the inner rotor 7, and the rib 431 and the shaft seat 433 of the metal supporting frame 43 provide the high-rigidity support for the stationary shaft 3a, so as to overcome the problem that the strength of the plastic material is reduced due to the temperature rise; the composite fixed shaft 3a is composed of a corrosion-resistant and wear-resistant metal shaft 32, a ceramic shaft sleeve 33 and a sealing nut 323; the metal shaft 32 passes through the center hole 332 of the ceramic shaft sleeve 33, is tightly locked in the thread hole 433b at the center of the shaft seat 433 of the supporting frame 43 by the thread part, and is tightly pressed on the end surface of the ceramic shaft sleeve 33 by the nut 321 at the thread part at the other end; the front end face of the ceramic bushing 33 is pressed against the pressing face 435 of the end face of the shaft seat 433 of the supporting bracket 43, and the rear end face of the ceramic bushing 33 is also pressed by the locking nut 321, so as to form a highly rigid composite fixed shaft 3a, and the cylindrical outer diameter of the sealing nut 323 can be supported and fixed by the shaft hole seat 413 of the rear cover 41.

Referring to fig. 7, the supporting frame 43 is a structure of two 90-degree ribs 431 extending from the inner side of the pump inlet 44 of the cast iron front cover 4 in the axial direction, the ribs 431 extend radially from the inner side of the pump inlet 44 of the cast iron front cover 4 to the center of the circle, and are combined with the center of the inner diameter to form two 90-degree rib right-angle members, and an arc cone 432 centered at the center of the circle is formed at the combination position from the inlet side, a shaft seat 433 is installed at the tail end of the arc cone, a thread hole 433b of the arc cone is used for tightly locking one end thread part of the metal shaft 32, the front end surface of the ceramic shaft sleeve 33 is tightly pressed on a pressing surface 435 on the end surface of the shaft seat 433 of the supporting frame 43, and the other end surface of the ceramic shaft sleeve is tightly pressed by a locking nut 321 on the other end thread part of the; the rib 431 is also lengthened along the axial extension of the cone 432, and the width of the plate is contracted to the outer diameter of the shaft seat 433, the outer side of the supporting frame 43 is completely covered with the rubber coating 43a by fluoroplastic and is integrated with the pump casing lining 4a, and the fixed shaft 3a will be equally applied to the supporting frame 43 to generate deformation and displacement when bearing radial force and moment;

referring to fig. 7, the middle portion of the fixed shaft 3a is coupled to the bearing 79 for supporting the rotation of the inner rotor 7, and the length of the middle portion is sufficient for the length of the bearing 79, and the fixed shaft 3a and its supporting structure should bear multiple load forces including gravity W, which is the force generated by the weight of the rotor, centrifugal force X, which is the eccentric centrifugal force generated by the center of mass of the rotor due to the gap of the bearing 79, lateral force P, which is the force applied to the impeller 5 caused by the uneven fluid pressure in the scroll flow passage 47 of the pump front cover 4, and the torque applied by each force.

Referring to fig. 7, when multiple load forces are applied to the fixed shaft 3a, the force arm generates a moment, the reference position of the force arm is based on the center a of the supporting frame 43, the gravity moment is the gravity W multiplied by the force arm WL, the centrifugal moment is the centrifugal force X multiplied by the force arm XL, the lateral moment is the lateral force P multiplied by the force arm PL, the eccentric centrifugal force X caused by the abrasion of the bearing 79 is the variation load source with the highest rigidity of the structure of the fixed shaft 3a, the eccentric centrifugal force X is larger as the abrasion amount is higher, the longest force arm XL exists from the center of the bearing 79 to the center a of the supporting frame 43, the shortest force arm is the lateral force P applied to the impeller caused by the uneven fluid pressure, the lateral force P causes the skew between the center of the inner rotor 7 and the center of the fixed shaft 3a to cause the continuous deformation of the supporting frame 43, and the deformation and displacement occur on the supporting frame 43, because, the moment it receives is more important and most of the forces and moments will be borne by the support 43 of the stationary shaft 3 a. Referring to fig. 7, since the strength of the corrosion-resistant plastic back cover 41 is reduced due to the temperature rise, if the center line C of the center reference point of the back cover bearing seat 413 is taken as the reference point, a part of the resultant force applied to the fixed shaft 3a is applied to the bearing seat 413 (as shown in fig. 1(B)), the moment applied thereto is also considered, the length of the moment arm is the distance from each force application position to the center line C, but since the fixed shaft 3a is designed to be highly rigid, most of the resultant force and moment are not applied to the bearing seat 413 (as shown in fig. 1(B)), and therefore, most of the force and moment applied to the fixed shaft 3 is borne by the supporting frame 43.

Claims

1. A kind of structure improvement of magnetic drive pump, it is a front cover with inlet support frame structure, the front cover made of cast iron or stainless steel has a pump inlet, volute runner, outlet, back flange and support frame, the space of the front cover is used to contain the impeller, the pump inlet is used to connect the impeller inlet, the impeller blade converts the shaft work into the flow work applied on the fluid, the fluid enters the volute runner and flows out from the outlet, the liquid-receiving side in the front cover is equipped with the lining to isolate the corrosive liquid, the flange is used to install the bracket and back cover behind its back side, it is used to prevent the leakage of the corrosive liquid, and the support frame which is integrated structure by the pump inlet inner diameter space, it is a cantilever structure extending axially to install the fixed shaft and couple with the inner rotor to drive the impeller; the method is characterized in that:

the supporting frame is a structure of two ribbed plates which are mutually 90 degrees and extend from the inner side of the axial direction of the inner diameter of the pump inlet of the front cover, the ribbed plates firstly extend out from the inner surface of the pump inlet of the cast iron front cover to the circle center in the radial direction, and are combined into two 90-degree ribbed plate right-angle components at the circle center of the inner diameter, an arc cone which takes the circle center as the center is formed at the combination position from the inlet side, and the tail end of the arc cone is provided with a shaft seat and the shaft hole of the shaft; the rib plate is also lengthened along with the axial extension of the cone, the width of the plate is contracted to the outer diameter of the shaft seat, and the outer side of the support frame is completely covered and encapsulated by fluoroplastic and is integrated with the inner lining of the pump shell; the inside lining rubber coating in shaft hole is sufficient compressive capacity when the installation fixed axle to provide the sufficient pre-compaction stress of fixed axle, and the degree of depth in shaft hole can provide and grip length L, reduces the deflection of fixed axle atress back shaft hole inside lining, makes the displacement volume of fixed axle reduce, and can transmit atress and moment by the support frame on the protecgulum.

2. A kind of structure improvement of magnetic drive pump, it is a front cover with compound fixed shaft structure of the inlet support frame, the front cover made of cast iron or stainless steel has a pump inlet, the volute runner, the outlet, the back flange, the support frame and compound fixed shaft, the space of the front cover is used to hold the impeller, the pump inlet is used to connect the impeller inlet, the impeller blade converts the shaft work into the fluid work which is applied on the fluid, the fluid enters the volute runner and flows out from the outlet, the liquid-receiving side of the front cover is equipped with the lining to isolate the corrosive liquid, the flange is used to install the bracket and back cover behind its back side, to prevent the leakage of the corrosive liquid, and the support frame which is an axial extending cantilever structure is used to lock the compound fixed shaft and couple with the inner rotor to drive the impeller; the method is characterized in that:

the support frame is a structure of two ribbed plates which are mutually 90 degrees and extend from the inner side of the axial direction of the inner diameter of the pump inlet of the front cover, the ribbed plates firstly extend out from the inner surface of the pump inlet of the cast iron front cover to the circle center in the radial direction and are combined into two 90-degree ribbed plate right-angle components at the circle center of the inner diameter, an arc cone which takes the circle center as the center is formed at the combination position from the inlet side, and a shaft seat is arranged at the tail end of the arc cone and is provided with; the rib plate is also lengthened along with the axial extension of the cone, the width of the plate is contracted to the outer diameter of the shaft seat, and the outer side of the support frame is completely covered and encapsulated by fluoroplastic and is integrated with the inner lining of the pump shell; the screw thread hole in the center of the shaft hole is used for tightly locking the screw thread part at one end of the metal shaft of the composite shaft; the end face of the shaft seat is divided into two annular faces, a pressing face and a sealing face, the pressing face is not coated with fluoroplastic rubber and is used for being tightly pressed and attached to the end face of the ceramic shaft sleeve to ensure the supporting rigidity of the fixed shaft, and the sealing face is coated with fluoroplastic rubber;

the metal shaft of the composite fixed shaft passes through the central hole of the ceramic shaft sleeve and is locked in the thread hole at the center of the shaft seat of the support frame by the thread part; the front end face of the ceramic shaft sleeve is tightly pressed on the pressing face and the sealing face of the shaft seat end face of the support frame, and the rear end face of the ceramic shaft sleeve is also tightly pressed by the locking nut to form a high-rigidity composite fixed shaft; the front end face of the ceramic shaft sleeve is tightly pressed and attached to the pressing face to ensure the supporting rigidity of the fixed shaft, and meanwhile, the front end face is tightly pressed and attached to a sealing face of the fluoroplastic rubber coating, so that the fluoroplastic rubber coating is compressed and the compression amount and the sealing effectiveness can be ensured; the screw cap encapsulated by the fluoroplastic is a cup-shaped cylindrical metal piece, one end of the sealing screw cap without an opening can be tightly locked on the thread at the tail end of the metal shaft by a tool, and the end face of the opening can be tightly pressed with the rear end face of the ceramic shaft sleeve, so that the sealing and corrosion-resistant functions of the composite fixed shaft are achieved;

because the high tightening force provided by the metal shaft is applied to the ceramic shaft sleeve, the composite fixed shaft is in a rigid shaft structure, the deformation and the displacement are reduced, and the stress and the torque can be transmitted to the front cover by the support frame.

3. The improved structure of the magnetic driving pump as described in claim 1, wherein: wherein the magnetic drive pump protecgulum has entry support frame structure person, and this magnetic drive pump is bilateral support fixed axle construction, and its part includes that the protecgulum contains support frame, impeller, back lid, inner rotor, outer rotor, fixed axle and bracket, wherein:

the front cover is made of cast iron or stainless steel and comprises a pump inlet, a scroll runner, an outlet, a rear flange and a support frame, wherein the space of the front cover is used for accommodating an impeller, the pump inlet is used for connecting the impeller inlet, the impeller blades convert shaft work into flow work applied to fluid, the fluid enters the scroll runner and flows out of the outlet, the liquid receiving side in the front cover is provided with a lining to isolate corrosive liquid, the flange behind the back side is used for installing a bracket and the rear cover to prevent the leakage of the corrosive liquid, and the support frame which is in an integral structure by the inner diameter space of the pump inlet is in an axially extending cantilever structure which is used for installing a fixed shaft and is coupled with an inner rotor to drive the impeller; two ribbed plates extending out from the inner diameter surface of the pump inlet towards the circle center and forming a cantilever structure axially extending through the hub hole of the impeller and a support frame integrated with the front cover to provide high-rigidity support for the fixed shaft;

the support frame is a cantilever structure which is completely coated and encapsulated by fluoroplastic and integrated with the pump shell and the liner thereof into a whole, and the support frame comprises two ribbed plates which are 90 degrees with each other and an axially extending cone; the two rib plates extend out from the inner surface of the pump inlet to the center of the circle and are combined with the cone; the axially extending cone is provided with a shaft seat and a shaft hole at the tail end by taking the center of the pump inlet as the center; the shaft seat passes through the hub hole of the impeller, and the conical arc of the shaft seat and the hub surface of the flow passage of the impeller form a smooth curved surface; the rib plate is also lengthened along with the axial extension of the cone and contracted to the outer diameter of the shaft seat to form a high-rigidity cantilever structure; the shaft hole of the shaft seat simultaneously provides a shaft holding length L so as to ensure the supporting rigidity of the fixed shaft;

the impeller is made of fluoroplastic and is arranged inside the front cover of the pump; the impeller hub is used for being combined with the axial extension part of the inner rotor, so that the impeller and the inner rotor form a whole or the impeller and the inner rotor are mutually embedded and combined into a whole; the opening of the impeller hub can allow the support frame to axially pass through, and the hub surface and the outer side of the cone form a smooth curved surface;

the back cover is a cup-shaped two-layer shell structure with a fluoroplastic lining and a strengthening layer; the bottom is provided with a shaft hole seat without any through hole, so that the rear cover is prevented from any leakage; the flange part at the front end is combined with the flange at the back of the front cover of the pump and the flange of the bracket to prevent the leakage of the corrosive liquid; the back side of the flange part is provided with a flange strengthening piece for ensuring the structural strength and the locking effect; the cylindrical part of the side edge of the outer rotor penetrates through the inner diameter space of the outer rotor; and the inner chamber space is used for installing the inner rotor; the rear cover is used for separating the inner rotor from the outer rotor and keeping a certain gap between the inner rotor and the outer rotor so as to ensure that the rear cover cannot be worn and damaged to cause leakage of corrosive liquid; the shaft hole seat is arranged at the center of the bottom of the rear cover, and the axial outer side of the shaft hole seat extends in the inner space of the outer rotor and is used for assisting in supporting one end of the fixed shaft; a metal ring is arranged between the two layers of shells outside the shaft hole of the shaft hole seat for reinforcing the fluoroplastic rubber coating of the shaft hole seat to prevent deformation;

the inner rotor is a ring-shaped structure formed by an inner magnet, a yoke and an axial extension part; and a zero-leakage-seam annular rotor rubber coating is coated by fluoroplastics; the middle hole of the inner rotor is provided with a bearing which is coupled with the fixed shaft to rotate; the impeller hub is used for being combined with the axial extension part of the inner rotor, so that the impeller and the inner rotor form a whole or the impeller and the inner rotor are mutually embedded and combined into a whole; the rear cover is used for separating the outer rotor and a certain gap is reserved between the inner side and the outer side of the rear cover;

the outer rotor is a ring-shaped cup-shaped structure formed by an outer magnet, a yoke and a connecting seat; the linking seat is combined and fixed with the axis of the driving motor, and the driving motor drives the outer rotor to rotate; when the outer rotor rotates, the inner rotor is driven to rotate;

the fixed shaft is of a bilateral support structure and is made of corrosion-resistant and wear-resistant equal-diameter ceramic materials, the front end of the fixed shaft is supported by the support frame of the front cover, and the rear end of the fixed shaft is supported and fixed by the shaft hole seat of the rear cover; the fixed shaft is coupled with a bearing of the inner rotor to rotate so as to bear the composite force borne by the inner rotor, and the high-rigidity support is provided by the support frame;

the bracket is a ring structure with two flanges; the flange on one end is used to lock and fix on the flange on the end of motor, and the flange on the other end is used to combine the flange part of back cover and the back flange on the back side of front cover of pump.

4. The improved structure of the magnetic driving pump as claimed in claim 2, wherein the magnetic driving pump is a dual-side supporting composite fixed shaft structure, and the components thereof include a front cover including a supporting frame and a composite fixed shaft, an impeller, a rear cover, an inner rotor, an outer rotor and a bracket, and characterized in that: wherein,

the front cover is made of cast iron or stainless steel and comprises a pump inlet, a scroll runner, an outlet, a rear flange, a support frame and a composite fixed shaft, wherein the space of the front cover is used for accommodating an impeller, the pump inlet is used for connecting the impeller inlet, the impeller blades convert shaft work into flow work applied to fluid, the fluid enters the scroll runner and flows out from the outlet, a lining is arranged on the liquid receiving side in the front cover to isolate corrosive liquid, the flange is used for installing a bracket and the rear cover behind the back side of the front cover to prevent the leakage of the corrosive liquid, and the support frame which is of an integrated structure is formed by the inner diameter space of the pump inlet and is of an axially extending cantilever structure which is used for tightly locking the composite fixed shaft and is coupled with the inner rotor to drive the; two ribbed plates extending out from the inner diameter surface of the pump inlet towards the circle center and forming a cantilever structure axially extending through the hub hole of the impeller and a support frame integrated with the front cover to provide high-rigidity support for the fixed shaft;

the support frame is a cantilever structure which is completely coated and encapsulated by fluoroplastic and integrated with the pump shell and the liner thereof into a whole, and the support frame comprises two ribbed plates which are 90 degrees with each other and an axially extending cone; the two ribbed plates extend out from the inner diameter surface of the pump inlet to the circle center and are combined with the cone; the axially extending cone is provided with a shaft seat and a shaft hole at the tail end by taking the center of the pump inlet as the center; the shaft seat passes through the hub hole of the impeller, and the conical arc of the shaft seat and the hub surface of the flow passage of the impeller form a smooth curved surface; the rib plate is also lengthened along with the axial extension of the cone and contracted to the outer diameter of the shaft seat to form a high-rigidity cantilever structure; the screw thread hole in the center of the shaft hole is used for tightly locking the screw thread part at one end of the metal shaft of the composite shaft; the end face of the shaft seat is divided into two annular faces, a tightening face and a sealing face, the tightening face is used for being tightly pressed and attached to the end face of the ceramic shaft sleeve to ensure the supporting rigidity of the fixing shaft, and the sealing face is coated with fluoroplastic rubber;

the metal shaft of the composite fixed shaft passes through the central hole of the ceramic shaft sleeve and is locked in the thread hole at the center of the shaft seat of the support frame by the thread part; the front end face of the ceramic shaft sleeve is tightly pressed on the pressing face and the sealing face of the shaft seat end face of the support frame, and the rear end face of the ceramic shaft sleeve is also tightly pressed by the locking nut to form a high-rigidity composite fixed shaft; the front end face of the ceramic shaft sleeve is tightly pressed and attached to the pressing face to ensure the supporting rigidity of the fixed shaft, and meanwhile, the front end face is tightly pressed and attached to a sealing face of the fluoroplastic rubber coating, so that the fluoroplastic rubber coating is compressed and the compression amount and the sealing effectiveness can be ensured; the screw cap encapsulated by the fluoroplastic is a cup-shaped cylindrical metal piece, one end of the sealing screw cap without an opening can be tightly locked on the thread at the tail end of the metal shaft by a tool, and the end face of the opening can be tightly pressed with the rear end face of the ceramic shaft sleeve, so that the sealing and corrosion-resistant functions of the composite fixed shaft are achieved; the cylindrical outer diameter of the sealing nut can be supported and fixed by the shaft hole seat of the rear cover;

the impeller is made of fluoroplastic and is arranged inside the front cover of the pump; the impeller hub is used for being combined with the axial extension part of the inner rotor, so that the impeller and the inner rotor form a whole or the impeller and the inner rotor are mutually embedded and combined into a whole; the impeller is characterized in that: the opening of the impeller hub can allow the support frame to axially penetrate through the opening to support one end of the fixed shaft, and the surface of the runner hub and the outer side of the cone form a smooth curved surface;

the back cover is a cup-shaped two-layer shell structure with a fluoroplastic lining and a strengthening layer; the bottom is provided with a shaft hole seat without any through hole, so that the rear cover is prevented from any leakage; the flange part at the front end is combined with the flange at the back of the front cover of the pump and the flange of the bracket to prevent the leakage of the corrosive liquid; the back side of the flange part is provided with a flange strengthening piece for ensuring the structural strength and the locking effect; the cylindrical part of the side edge of the outer rotor penetrates through the inner diameter space of the outer rotor; and the inner chamber space is used for installing the inner rotor; the rear cover is used for separating the inner rotor from the outer rotor and keeping a certain gap between the inner rotor and the outer rotor so as to ensure that the rear cover cannot be worn and damaged to cause leakage of corrosive liquid; the shaft hole seat is arranged at the center of the bottom of the rear cover, and the axial outer side of the shaft hole seat extends in the inner space of the outer rotor and is used for assisting in supporting one end of the composite fixed shaft; a metal ring is arranged between the two layers of shells outside the shaft hole of the shaft hole seat for reinforcing the fluoroplastic rubber coating of the shaft hole seat to prevent deformation;

5. An improved structure of magnetic drive pump, the inlet flow channel of the magnetic drive pump has a structure with low flow resistance, wherein, the inlet flow channel structure means that the fluid flows in from the pump inlet, passes through the ribbed plate of the supporting frame to reach the impeller inlet, and then is guided by the shaft seat conical curved surface and the impeller hub surface to turn from the axial direction to the radial flow, the inlet flow channel structure includes the pump inlet, the supporting frame, the impeller and the volute flow channel, characterized in that:

the inner diameter cylindrical surface of the pump inlet, the inlet curved surface of the front cover of the impeller and the front cover surface of the flow passage form a smooth curved surface, and the sectional area of the cylindrical surface is appropriately enlarged in accordance with the blocking area of the rib plate to maintain the stable flow rate;

the supporting frame is composed of two ribbed plates which are extended from the inner side of the pump inlet to the center of circle and are 90 degrees to each other, and a cone which is provided with an axle seat at the tail end and is arranged at the center of circle of inner diameter, and the two form a cantilever structure which axially extends through the hub hole of the impeller and is integrated with the front cover; the diameter of the front end of the cone is equal to the thickness of the rib plate, and the diameter is increased to the outer diameter of the shaft seat in a conical curved surface mode after the front end of the cone axially extends to the inlet of the impeller; namely, the blocking area of the inner diameter space of the inlet flow passage is mainly caused by the rib plates; the rib plate is also lengthened along with the axial extension of the cone and contracted to the outer diameter of the shaft seat, and the rib plate has enough length to provide the rectification effect;

the curved surface of the cone and the concave curved surface of the hub surface of the flow channel of the impeller form a smooth curved surface, wherein, the flow velocity of the fluid is increased and the disturbance is generated after the fluid flows through the arc front edge of the ribbed slab, because the ribbed slab has better length, the fluid can provide the fluid rectification effect to flow smoothly and reduce the flow resistance, the fluid flows out from the arc rear edge of the ribbed slab, flows into the front edge of the blade after passing through the space flow field, the fluid is smoothly converted into radial flow from the curved surface of the cone in the axial direction, and the low flow resistance can be ensured because the streamline of the fluid has better curvature radius;

the impeller is of a centrifugal structure, the front cover surface of the impeller is designed to be connected with the vertical axis, and the curved surface at the inlet of the impeller has a proper curvature radius, so that the inner diameter cylindrical surface at the inlet of the pump and the curved surface at the inlet of the front cover of the impeller form a smooth curved surface; the hub surface near the front edge of the blade has an inward concave curved surface, which can match the curved surface of the cone of the support seat to make the front edge of the blade of the impeller have sufficient flow area and ensure the streamline of the fluid to have a better curvature radius;

the volute flow passage is front side volute structure, and the central line of flow passage of the impeller is positioned in the inner side of pump outlet centre, i.e. the impeller inlet has a better axial length from pump inlet, and the internal diameter cylindrical surface of pump inlet has a smaller expansion angle.