# US 5,708,313 A · Sump pump

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- Number: US 5,708,313 A
- Document ID: US5708313A
- Status: Granted
- Kind: A
- Application number: 08/738,816
- Filed: 1996-10-28
- Granted: 1998-01-13
- Earliest claimed: 1996-10-28
- Assignees: Finish Thompson Inc.
- Inventors: H. David Bowes; Jeffrey S. Richmond
- Web page: https://patentgrep.com/patent/US5708313A

## CPC

- H02K 49/106: {with a radial air gap}
- F04D 13/027: {Details of the magnetic circuit}
- H02K 5/128: using air-gap sleeves or air-gap discs
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02)

## Abstract

A sealess sump pump comprises an impeller chamber mounted at the bottom of a pump column, an impeller journaled in the impeller chamber, a rare earth driven magnet assembly fixed to rotate with the impeller, a rare earth driving magnet assembly mounted at the lower end of an elongate pump shaft and a nonmagnetic barrier between the driving and the driven magnet assemblies.

## Claims

### Claim 1

A sealess sump pump having an electric motor and an impeller chamber spaced from the electric motor so that the impeller can be immersed in a liquid filled sump comprising:
an electric motor having a motor shaft extending downwardly therefrom;
a pump column extending downwardly from the motor;
an impeller chamber mounted at the bottom of the pump column, said impeller chamber having an inlet port and an outlet port;
an impeller journaled in the impeller chamber which when caused to rotate draws liquid into the inlet port and forces liquid out the outlet port;
a driven magnet assembly fixed to rotate with the impeller;
an elongate shaft extending downward from the motor shaft within the pump column, the length of said shaft and the driving magnet assembly being at least 8 inches;
a driving magnet assembly mounted at the lower end of the elongate shaft; and
a cylindrical nonmagnetic barrier between the driving and the driven magnet assemblies which seals the lower end of the pump column;
said driving magnet assembly comprising a ferromagnetic ring with an even number of rare earth magnets equally spaced around the inner circumference of the ring, said magnets radially polarized and alternating in polarity;
said driven magnet assembly having a ferromagnetic ring with a number of rare earth magnets equal to the number of magnets in the driving magnet assembly equally spaced around the outer circumference of the ring, said magnets being radially polarized and alternating in polarity.

### Claim 2 (depends on 1)

A sump pump according to claim 1, in which the distance between the motor face and an intermediate bearing supporting the shaft is at least 8 inches.

### Claim 3 (depends on 1)

A sump pump according to claim 1, in which the lower end of the shaft is supported radially and/or axially by a bearing or bushing fixed to the driving magnetic assembly side of the nonmagnetic barrier.

### Claim 4 (depends on 1)

A sump pump according to claim 1, wherein the impeller and driven magnet assembly have no mechanical thrust bearing and are held in the axial position by the attraction of the magnets in the driving and driven magnet assemblies.

### Claim 5 (depends on 1)

A sump pump according to claim 1, wherein the shaft housing is sealed to the motor to define a hermetically sealed space surrounding the shaft.

### Claim 6 (depends on 1)

A sump pump according to claim 1, wherein the radial clearance between the driving and driven magnetic assemblies are spaced at least 1/32 of an inch from the nonmagnetic barrier.

### Claim 7 (depends on 1)

A sump pump according to claim 1, wherein the radial distance between the driving and driven magnet cylindrical surfaces is at least 1/4 of an inch.

### Claim 8 (depends on 1)

A sump pump according to claim 1, wherein the driven magnet assembly is radially outward of the driving magnet assembly.

### Claim 9 (depends on 1)

A sump pump according to claim 1, wherein the driving magnet assembly is radially outward of the driven magnet assembly.