# US 7,611,338 B2 · Tandem ESP motor interconnect vent

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- Number: US 7,611,338 B2
- Document ID: US7611338B2
- Status: Granted
- Kind: B2
- Application number: 11/387,184
- Filed: 2006-03-23
- Published: 2007-09-27
- Granted: 2009-11-03
- Earliest claimed: 2006-03-23
- Assignees: Baker Hughes Incorporated
- Inventors: Mike Allen Swatek; Van J. McVicker
- Web page: https://patentgrep.com/patent/US7611338B2

## CPC

- F04D 13/10: adapted for use in mining bore holes
- H02K 5/132: Submersible electric motors (H02K5/128 takes precedence)
- H02K 7/003: {Couplings; Details of shafts (means for mounting rotors on shafts H02K1/28)}
- H02K 16/00: Machines with more than one rotor or stator {(machines for transmitting mechanical power from a driving shaft to a driven shaft and comprising structurally interrelated motor and generator parts H02K51/00; permanent magnet machines with multiple rotors or stators relatively rotated for vectorially combining the excitation fields or the armature voltages H02K21/029)}
- H02K 2205/09: Machines characterised by drain passages or by venting, breathing or pressure compensating means
- F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02)
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})

## Abstract

An electrical submersible well pump assembly has upper and lower motors that are filled with oil. During installation in a well, the upper motor lowers into engagement with the lower motor. The drive shafts of the motors have splined ends that engage each other within a central cavity. A vent port leads from the central cavity to the exterior for venting any trapped air located within the central cavity.

## Claims

### Claim 1

A method of connecting tandem upper and lower subs of an electrical submersible pump assembly, the upper sub having a base that interconnects with a head of the lower sub, each of the subs having a drive shaft with a splined end that mates with the splined end of the other drive shaft, the base of the upper sub having a central cavity surrounding the splined end of the drive shaft of the upper sub, the method comprising:
(a) providing a vent port in the base of the upper sub extending from the central cavity to an exterior of the base of the upper sub;
(b) introducing a quantity of oil into each of the subs while the subs are apart from each other to substantially fill each of the subs; then
(c) opening the vent port, and with a lower end of the central cavity open, lowering the upper sub downward into engagement with the lower sub, which causes oil in the upper sub to flow downward and into the central cavity, the open vent port allowing any air trapped in the central cavity to displace out through the vent port.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising after step (c): closing the vent port and topping up the oil in the upper sub to replace the oil that flowed downward from the upper sub during step (c).

### Claim 3 (depends on 1)

The method according to claim 1, further comprising:
providing a communication passage through the base that is separated from the central cavity; and wherein
step (c) comprises flowing the oil downward through the communication passage into the head of the lower sub and back upward into the central cavity.

### Claim 4 (depends on 3)

The method according to claim 3, wherein step (a) comprises isolating the vent port from the communication passage.

### Claim 5 (depends on 3)

The method according to claim 3, further comprising placing a check valve in the communication passage to restrict downward flow of oil through the communication passage, the check valve automatically opening when the base of the upper sub engages the head of the lower sub.

### Claim 6 (depends on 1)

The method according to claim 1, further comprising after step (c): closing the vent port and pumping oil up into the upper sub through a port separate from the vent port to replenish oil that flowed downward from the upper sub in step (c).

### Claim 7

A method of connecting tandem upper and lower motors of an electrical submersible pump assembly, the upper motor having a base that interconnects with a head of the lower motor, each of the motors having a drive shaft, the drive shafts having mating splined ends, the base of the upper motor having a central cavity surrounding one of the splined ends of the drive shaft of the upper motor, the base of the upper motor having a communication passage separated from the central cavity, the method comprising:
(a) providing a vent port in the base of the upper motor extending from an exterior of the base of the upper motor to the central cavity;
(b) substantially filling the motors separately with oil; then
(c) suspending the upper motor above the lower motor, with the central cavity facing downward and a lower end of the central cavity open, which causes any oil within the central cavity to flow out, thereby leaving an air pocket in the central cavity;
(d) opening the vent port and lowering the base of the upper motor onto the head of the lower motor, causing oil to flow down the communication passage from the upper motor and into the central cavity, and displacing air of the air pocket out the vent port; then
(e) closing the vent port and introducing more oil into the upper motor to replace oil drained during steps (c) and (d).

### Claim 8 (depends on 7)

The method according to claim 7, wherein step (a) comprises separating the vent port from the communication passage.

### Claim 9 (depends on 7)

The method according to claim 7, wherein in step (d), the oil displacing the air pocket flows downward and out of the communication passage, then up into the central cavity from the open lower end of the central cavity.

### Claim 10

A method of connecting tandem upper and lower motors of an electrical submersible pump assembly, the upper motor having a base that interconnects with a head of the lower motor, each of the motors having a drive shaft, the drive shafts having mating splined ends, the base of the upper motor having a central cavity surrounding one of the splined ends of the drive shaft of the upper motor, the base of the upper motor having a communication passage separated from the central cavity, the method comprising:
(a) providing a vent port in the base of the upper motor extending from an exterior of the base of the upper motor to the central cavity and separated from the communication passage;
(b) substantially filling the motors with oil while the motors are apart from each other; then
(c) suspending the upper motor above the lower motor, with the central cavity facing downward and a lower end of the central cavity open, thereby resulting in an air pocket in the central cavity;
(d) opening the vent port and lowering the base of the upper motor onto the head of the lower motor, causing oil to flow down the communication passage from the upper motor and back up into the central cavity, the oil flowing back up into the central cavity displacing air from the air pocket out the vent port; then
(e) closing the vent port and introducing more oil into the upper motor to replace oil that flowed from the upper sub during step (d).