Permanent magnet motor pump

• US 9,951,778 B2
• Filed: 08/12/2016
• Issued: 04/24/2018
• Est. Priority Date: 10/26/2011
• Status: Active Grant

• Current Assignee: Assoma Inc.
• Original Assignee: Assoma Inc.
• Inventors: Chien, Huan-Jan, Wang, Chin-Cheng, Shih, Chih-Hsien
• Primary Examiner(s): Plakkoottam, Dominick L
• Application Number:
  US15/236,306
• Publication Number:
  US 20160348683A1
• Time in Patent Office: 620 Days
• CPC Class Codes: F04B 2207/70 Warnings
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04C 2270/78 Warnings
• CPC Class Codes: F04D 13/026 Details of the bearings
• CPC Class Codes: F04D 13/0626 Details of the can
• CPC Class Codes: F04D 13/0633 Details of the bearings
• CPC Class Codes: F04D 15/0088 Testing machines
• CPC Class Codes: F04D 15/0094 Indicators of rotational movement
• CPC Class Codes: F04D 29/046 Bearings
• CPC Class Codes: F04D 29/0465 Ceramic bearing designs
• CPC Class Codes: F04D 29/22 specially for centrifugal pumps
• CPC Class Codes: F04D 29/4286 inside lining, e.g. rubber
• CPC Class Codes: F04D 7/06 the fluids being hot or corrosive, e.g. liquid metals
• CPC Class Codes: F05B 2240/14 Casings, housings, nacelles, gondels or the like, protecting or supporting assemblies there within
• CPC Class Codes: F05B 2240/52 Axial thrust bearings
• CPC Class Codes: F05B 2280/4003 Synthetic polymers, e.g. plastics
• CPC Class Codes: G01M 13/04 Bearings
• CPC Class Codes: G01R 33/07 Hall effect devices
• CPC Class Codes: G01R 33/077 Vertical Hall-effect devices
• CPC Class Codes: H02K 11/20 for measuring, monitoring, testing, protecting or switching rectifiers H02K11/04; power electronics H02K11/33
• CPC Class Codes: H02K 11/215 : Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements
• CPC Class Codes: H02K 5/1677 : radially supporting the rotor around a fixed spindle; radially supporting the rotor directly

Abstract

A structural improvement of the canned pump is to improve the stiffness of a stationary shaft and, according to requirement, to dispose a monitor device. The method for improving the stiffness of the stationary shaft includes axially inserting a shaft metal rear support of the metal structural of a motor rear casing of a canned motor into the inner side of a rotor yoke of an inner rotor of the canned motor, tightly attaching the shaft metal rear support to a rear shaft seat for improving the stiffness of the stationary shaft by longer hold length, and for shortening an arm length of the composite force. The monitor device, used for detecting the wear of a bearing for enhancing the reliability and satisfying the driving requirement, is installed in the ring slot to be protected by the rear shaft seat.

Claims

1. A permanent magnet motor pump comprises a pump casing, an impeller, a containment shell, a stationary shaft, a motor and a monitor device, wherein:

the pump casing includes an inlet, an outlet and a flow channel, and is used for containing the impeller, a front thrust ring, installed on an inner side of the inlet of the pump casing, is used for mating with a front thrust bearing of the impeller to form a front axial thrust bearing together;

the impeller is assembled in the pump casing, a hub plate is used for combining an axially extended part of an inner rotor of the motor so that the impeller and the inner rotor are integrated into one piece or embedded to be combined into one piece;

the containment shell is a cup-shaped shell structure comprising a rear shaft support positioned on a bottom side of the containment shell, and a concave aperture on an outer side of the containment shell, the concave aperture has a ring-shaped surface for installing the monitor device which is used for detecting a mechanical wear of a ceramic bearing, a rear thrust ring is installed on a front surface of a shaft hold hole and is used for mating with the ceramic bearing of the inner rotor to form a rear axial thrust bearing;

a shell flange part is positioned on a front side of the containment shell and combined with the pump casing and a pump side flange of the motor;

a shell column part is on a lateral side of the containment shell and passes through the inner side of a stator of the motor with a loose slide fit, a motor rear casing of the motor is combined with the bottom side of the containment shell;

the stationary shaft is made of a ceramic material, the stationary shaft mates with the ceramic bearing for supporting a rotation of the inner rotor;

the stationary shaft is installed on a shaft metal rear support of the motor rear casing, mates with the ceramic bearing to support the rotation of the inner rotor;

the motor comprises the stator, a motor casing, the motor rear casing and the inner rotor;

the stator is fixed in the motor casing, windings are winded on the stator, a PWM electric power is applied on the windings and generates a magnetic flux to interact with a magnetic flux of the inner rotor to generate torque and drive the impeller, the containment shell prevents the windings of the stator from being corroded by a corrosive fluid;

the motor casing has the pump side flange used for fixing with the shell flange part and the pump casing to prevent a leakage from the corrosive fluid, a back flange of the motor casing is used for fixing the motor rear casing with the shaft metal rear support;

the motor rear casing is fixed on the back flange of the motor casing,

the shaft metal rear support positioned at a center of the motor rear casing, and is combined with the rear shaft support to form the metal holding support; and

the inner rotor which is installed in an inner space of the containment shell is a ring-shaped structure comprising main magnets, a rotor yoke and the axially extended part, the main magnets are installed on an outer surface of the rotor yoke with a symmetric angular positions, the inner rotor is covered with an engineering plastic with anti-corrosion property, the ceramic bearing is installed in a central hole of the inner rotor for mating with the stationary shaft to bear a composite force, the axially extended part combines with the hub plate of the impeller so that the impeller and the inner rotor are integrated into one piece or embedded to be combined with each other into one piece;

an inner space of the rotor yoke contains the rear shaft support of the containment shell and the shaft metal rear support of the motor rear casing, which extend inwardly and axially in the inner space, an inner surface of the rotor yoke close to the bottom side of the containment shell is used for installing a plurality of secondary magnets, and each of the secondary magnets and each of the main magnets which are back to back to each other, have same magnetic pole in a radial direction of the stationary shaft;

the monitor device comprises the plurality of secondary magnets and a monitor set;

a number of the secondary magnets is the same as main magnets, the secondary magnets are assembled at one end of an inner side of the rotor yoke of the inner rotor of the bottom side of the containment shell, the secondary magnets are encapsulated with the main magnets in the inner rotor to prevent from being corroded by the corrosive fluid;

an axial length of the secondary magnets is at least more than twice as great as a length of an axial movement of the inner rotor, the length of the axial movement equals to a length of a rear axial free space between the ceramic bearing and the rear thrust ring, a magnetic flux line emitted from a surface of one of the plurality of secondary magnets forms a secondary magnetic loop which coexists with a main magnetic loop in the rotor yoke; and

the monitor set comprises a ring-shaped secondary yoke and multiple monitor elements, the monitor elements are installed on a surface of the ring-shaped secondary yoke with ferromagnetic material, and the secondary yoke and the multiple monitor elements are encapsulated as a set with an isolating material;

the inner side of the secondary yoke is fixed with an outer-diameter surface of the shaft metal rear support;

a secondary magnetic pole alignment point is positioned on a rear end of the secondary yoke and connected to an axis alignment point of the shaft metal rear support or the shaft metal rear support and a magnetic pole alignment point of a winding stator of the stator;

a front axial end and a rear axial end of the secondary magnets do not exceed a front axial end and a rear axial end of the secondary yoke, the monitor elements cut the magnetic flux lines to output voltage signals while the inner rotor rotates.

2. The permanent magnet motor pump according to claim 1, wherein an axial width of a front axial free space must be greater than a sum of an amount of wear allowance of the front thrust ring and the front thrust bearing, and a width of an axial gap is increased accordingly when the front axial free space is reduced.

3. The permanent magnet motor pump according to claim 1, wherein a width of an axial gap must be greater than a total amount of the rear axial free space, and a mate wear of the surface of the ceramic bearing and the surface of the rear thrust ring.

4. The permanent magnet motor pump according to claim 1, wherein a number of the monitor elements is even and at least four, the axial length of each of the monitor elements is not less than a sum of the length of the secondary magnets and the length of an axial free-movement, including a limit value of a wear of the front thrust bearing, of the inner rotor, and a width of a circumference of the monitor elements is not greater than an arc length between adjacent two center points of two secondary magnets.

5. The permanent magnet motor pump according to claim 4, wherein the monitor elements are signal coil pairs, the monitor set comprises the secondary yoke and the multiple signal coil pairs, and the axial movement of the inner rotor, a radial movement of the inner rotor and an angle of the inner rotor are obtained by calculating an electromotive voltage signal.

6. The permanent magnet motor pump according to claim 1, wherein a number of the monitor elements is even and at least four, the axial length of each the monitor elements is not less than a sum of the length of the secondary magnets and an axial free-movement, including a limit value of a wear of the front thrust bearing, of the inner rotor, and a width of a circumference of the monitor elements is not greater than an arc length between adjacent two center points of two secondary magnets.

7. The permanent magnet motor pump according to claim 6, wherein the monitor elements are signal coil pairs, the monitor set comprises the ring-shaped secondary yoke and the multiple signal coil pairs, and the axial movement of the inner rotor, a radial movement of the inner rotor and an angle of the inner rotor are obtained by calculating an electromotive voltage signal.

8. The permanent magnet motor pump according to claim 1, wherein the monitor elements are signal coil pairs, the monitor set comprises the ring-shaped secondary yoke and the multiple signal coil pairs, the multiple signal coil pairs are installed and arranged on the surface of the ring-shaped secondary yoke, and along a circumferential direction, the signal coil pairs are divided into two groups which are signal coils α

and β

, and a phase difference of an electric included angle between the two groups is 90 or 270 degrees;

the positioning of the electric included angle and a space included angle of the signal coil pairs are obtained by a magnet alignment point of the ring-shaped secondary yoke which is used for repairing and exchanging the monitor set.

9. The permanent magnet motor pump according to claim 8, wherein the axial movement of the inner rotor, a radial movement of the inner rotor and an angle of the inner rotor are obtained by calculating an electromotive voltage signal.

10. The permanent magnet motor pump according to claim 8, wherein each of the signal coil pairs is arranged to cover at least more than a half of the axial length of the ring-shaped secondary yoke, each front and rear end of the signal coil pairs is adjacent to each other respectively.

11. The permanent magnet motor pump according to claim 8, wherein each of the signal coil pairs is arranged to cover at least more than a half of the axial length of the ring-shaped secondary yoke, each front and rear end of the signal coil pairs are staggered to each other.

12. The permanent magnet motor pump according to claim 8, wherein each of the signal coil pairs is arranged to cover at least more than a half of the axial length of the ring-shaped secondary yoke, each signal coil pairs are arranged in the space included angle of 180 degrees.

13. The permanent magnet motor pump according to claim 8, wherein the axial length of the ring-shaped secondary yoke is greater than a total axial length of the arranged signal coil pairs, the signal coil pairs completely located between the front end and the rear end of the ring-shaped secondary yoke, and a range of a axial movement of second magnets of the inner rotor does not exceed the axial length of the ring-shaped secondary yoke.

14. The permanent magnet motor pump according to claim 1, wherein the monitor elements comprises multiple signal coil pairs and multiple hall sensors, the multiple signal coil pairs are installed on the surface of the ring-shaped secondary yoke, and along a circumferential direction, the signal coil pairs are divided into two groups which are signal coils α

and β

, and a phase difference of an electric included angle between the two groups is 90 or 270 degrees;

the position of the electric included angle and a space included angle of the signal coil pairs are obtained by a magnet alignment point of the secondary yoke which is used for repairing and exchanging the monitor set;

phase differences of electric included angles of three hall sensors are 120 degrees, respectively, one of the hall sensors which is at a center position is installed and faces a center of one of the signal coil pairs, phase differences of electric included angles of another two of the hall sensors located out of the signal coil pairs are 120 degrees.

15. The permanent magnet motor pump according to claim 1, wherein the stationary shaft is double-sided-supported stationary shaft structure, the rear shaft support of the containment shell is a blank rear shaft support, the blank rear shaft support has a ring slot, there is no through hole on the blank rear shaft support;

the blank rear shaft support is positioned at a center of the bottom side of the containment shell and extends inwardly and axially to the inner space of the rotor yoke;

the blank rear shaft support includes the shaft hold hole protruding inwardly, and a ring slot opening on an outer side of the shaft hold hole;

a front side of the stationary shaft is supported by a triangle front support, which installed at the inlet of the pump casing, the stationary shaft mates with the ceramic bearing for supporting the rotation of the inner rotor.

16. The permanent magnet motor pump according to claim 1, wherein the stationary shaft is a single-sided-supported cantilever stationary shaft structure, the rear shaft support of the containment shell has a rear shaft seat with a hole;

the rear shaft seat is combined with a composited shaft metal rear support to form a metal composited support, an outer ring-shaped surface of the composited shaft metal rear support is used for installing the ring-shaped secondary yoke, and a seal surface of the rear shaft seat is combined by a surface of a ceramic shaft sleeve including an O ring and the composited shaft metal rear support makes no leakage;

a composited stationary shaft comprises the ceramic shaft sleeve, a metal shaft and the motor rear casing, an end of the composited stationary shaft is installed on the composited shaft metal rear support of the motor rear casing, mates with the ceramic bearing to support the rotation of the inner rotor;

the metal shaft passes through a sleeve central hole of the ceramic shaft sleeve, and includes a circular head which is positioned at an end of the metal shaft covered with a resin enclosure, and pressed against a front end surface of the ceramic shaft sleeve, a teeth part of the metal shaft passes through the rear shaft seat of the containment shell and a central hole of the composited shaft metal rear support of the motor rear casing which is extended inwardly in a radial direction, a nut of the teeth part is fixed on the motor rear casing so that two ends of the ceramic shaft sleeve are pressed against the circular head and the composited shaft metal rear support to form the high-stiffness composited stationary shaft;

a sliding thrust surface of the ceramic shaft sleeve is pressed against a surface of the composited shaft metal rear support, and a respective O rind is installed at each of the two ends of the ceramic shaft sleeve to form a sealing system.