Patent Description:
ESP's are often used to pump well fluid from hydrocarbon wells. One common type of motor for an ESP is an induction electric motor having stator windings encircling a rotor mounted to a drive shaft. The rotor is made up of a number of rotor sections spaced apart from each other by motor bearings. Each rotor section has a stack of steel laminations with copper rods extending through them. A key and keyway slot arrangement couples each rotor section to the shaft for rotation. Three-phase power applied to the stator windings induces rotation of the rotor and the shaft.

An ESP induction electric motor may be of a length up to about <NUM> feet. To increase the overall horsepower, induction electric motors are commonly mounted in tandem. The lower end of an upper tandem motor is electrically connected to the upper end of a lower tandem motor. A power cable leading from the surface of the well to the upper tandem motor sends three-phase alternating current through the windings of the upper tandem motor stator and the windings of the lower tandem motor stator in series. The drive shaft of the upper tandem motor has a lower splined end that connects to the upper splined end of the lower tandem motor with an internally splined coupling.

Another type of ESP motor has permanent magnets in the rotor sections rather than copper rods. Each permanent magnet is typically made up of a stack of individual magnets in a column mounted within a slot in the stack of steel laminations. Each permanent magnet provides one pole of the motor, which may have four or a different number of poles. The key and slot arrangement of each rotor section axially aligns the pole magnets of each rotor section with the pole magnets in the other rotor sections.

Permanent magnet ESP motors have not been operated in tandem. A reason is that for proper operation, the pole magnets of a lower tandem motor would need to be rotationally aligned with the pole magnets of the upper tandem motor. The rotors of ESP motors, whether induction or permanent magnet, are enclosed in a housing and not visible. Being unable to see the rotor sections is not of concern to technicians connecting induction electric ESP motors in tandem because the copper rods in each rotor do not need to be rotationally aligned with each other. An ESP is known from <CIT>.

An electrical submersible well pump assembly has first and second motors, each having a housing. The first and second motors have first and second drive shafts, respectively. Each of the first and second motors have a plurality of rotor sections and a rotor keyway between each of the rotor sections and the shaft of each of the motors, defining magnetic poles. Each of the rotor sections has a plurality of circumferentially spaced permanent magnets. The second drive shaft having a splined end with external splines. A coupling connected with the first drive shaft for rotation in unison has internal splines that engage the external splines for causing the first and second drive shafts to rotate in unison. A housing connector connects the housings of the first and second motors. The connector has a bore with the coupling located therein. Alignment means rotationally aligns the magnetic poles of the first drive shaft with the magnetic poles of the second drive shaft prior to securing the housings of the first and second motors together.

In one embodiment, the alignment means comprises a coupling irregularity in the internal splines that is at a controlled orientation relative to the rotor keyway of the first shaft. A shaft irregularity in the external splines of the second shaft prevents the second drive shaft from fully engaging the coupling unless the shaft irregularity is in a specified rotational position relative to the coupling irregularity. The shaft irregularity is at a controlled orientation relative to the rotor keyway of the second shaft.

In one embodiment, the coupling irregularity comprises an irregularity spacing between two of the internal splines that differs from a uniform spacing between remaining ones of the internal splines. The shaft irregularity comprises an irregularity spacing between two of the external splines that has a same width as the irregularity spacing. Remaining ones of the external splines have a uniform spacing between them.

In a second embodiment, the alignment means comprises a coupling keyway in the coupling that is at a controlled orientation relative to the rotor keyway of the first shaft. A second shaft splined end keyway between the external splines is at a controlled orientation relative to the rotor keyway of the second shaft. A coupling key inserts within the coupling keyway and the second shaft splined end keyway.

In a third embodiment, the alignment means comprises a coupling indicia on an exterior of the coupling that is at a controlled orientation relative to the rotor keyway of the first shaft. A shaft indicia on an exterior of the splined end of the second shaft is at a controlled orientation relative to the rotor keyway of the second shaft.

In a fourth embodiment the alignment means comprises a protuberance on an exterior of the second shaft adjacent the splined end of the second shaft. The protuberance is at a controlled orientation relative to the rotor keyway of the second shaft. An orientation slot on the second end of the coupling has two edges facing each other and curves from a circumferentially wider dimension at an entrance to a guide slot portion. The guide slot portion is at a controlled orientation relative to the rotor keyway of the first shaft. The protuberance has a width for close reception within the guide slot portion. Moving the splined shaft of the second shaft towards the first motor causes the protuberance to enter the orientation slot, which rotates the second shaft until the protuberance enters the guide slot portion.

In the fourth embodiment, the internal splines in the coupling are located axially between the guide slot portion and the first shaft, so that the external splines engage the internal splines only after the protuberance enters the guide slot portion.

In the fourth embodiment, the protuberance may comprise a pair of guide members on an exterior of the second shaft adjacent the splined end of the second shaft and spaced <NUM> degrees apart from each other relative to an axis of the second shaft, each of the guide members being at a controlled orientation relative to the rotor keyway of the second shaft. The orientation slot comprises a pair of orientation slots on the second end of the coupling, each of the orientation slots having two edges facing each other and curving from a circumferentially wider dimension at an entrance to a linear guide slot portion. The guide slot portion is at a controlled orientation relative to the rotor keyway of the first shaft. Moving the splined shaft end of the second shaft towards the first motor causes the guide members to contact and slide along the edges of the orientation slots, rotating the second shaft until the guide members enter the guide slot portions.

While the disclosure will be described in connection with one embodiment, it will be understood that it is not intended to limit the disclosure to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the scope of the claims.

The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. In an embodiment, usage of the term "about" includes +/- <NUM>% of the cited magnitude. In an embodiment, usage of the term "substantially" includes +/- <NUM>% of the cited magnitude.

It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation.

Referring to <FIG>, a well has casing <NUM> that is perforated or has other openings to admit well fluid. An electrical submersible pump assembly or ESP <NUM> is illustrated as being supported on production tubing <NUM> extending into the well. Alternately, ESP <NUM> could be supported by other structure, such as coiled tubing. The terms "upper," "lower" and the like are used herein only for convenience, because ESP <NUM> can be operated in inclined or horizontal sections of a well. ESP <NUM> has several modules, including an upper tandem motor <NUM> and a lower tandem motor <NUM>. Upper motor <NUM> could be considered to be a first motor and lower motor <NUM> a second motor, or vice-versa. More than two tandem motors could be employed.

Each motor <NUM>, <NUM> is a three-phase permanent magnet electrical motor. A motor protector or seal section <NUM> connects to upper motor <NUM> and has components, such as a bladder, for reducing a pressure differential between lubricant in motors <NUM>, <NUM> and the hydrostatic pressure of well fluid on the exterior. The pressure equalizer of seal section <NUM> may be mounted to an upper end of upper motor <NUM> or alternately to a lower end of lower motor <NUM>.

A pump <NUM> connects to seal section <NUM>. Pump <NUM> has a well fluid intake <NUM> that will be at the base of pump <NUM>. Pump <NUM> is normally a rotary pump, such as a centrifugal or progressing cavity pump, but it could be a reciprocating pump. A gas separator (not shown) could be located at the bottom of pump <NUM>, and if so, intake <NUM> would be in the gas separator. The connections between the modules of ESP <NUM> are shown as bolted flanges, but they could be threaded connections.

A power cable <NUM> extends from a wellhead (not shown) alongside tubing <NUM> for supplying power to motors <NUM>, <NUM>. A motor lead <NUM>, which may be considered to be a lower part of power cable <NUM>, connects to a lower end of power cable <NUM> by a splice <NUM> in this example. Motor lead <NUM> extends alongside ESP <NUM> and has an electrical connector <NUM> on its lower end that secures to a receptacle at the upper end of upper motor <NUM>. Splice <NUM> is illustrated at the upper end of pump <NUM>, but it could be a considerable distance above pump <NUM>.

<FIG> illustrates interior portions of upper motor <NUM>, and these portions of lower motor <NUM> may be identical. Upper motor <NUM> has a housing <NUM> containing a non-rotating stator <NUM>. Stator <NUM> is conventional, having a stack of thin steel discs or laminations <NUM>. Windings <NUM> (shown in one of the slots in <FIG>) extend through slots in laminations <NUM>. Stator <NUM> has a cylindrical central bore <NUM> with a longitudinal axis <NUM>. A rotatable drive shaft <NUM> extends through bore <NUM> on axis <NUM> for driving pump <NUM> (<FIG>).

Rotor sections <NUM> are mounted to shaft <NUM> for causing shaft <NUM> to rotate. Rotor sections <NUM> are positioned along the length of shaft <NUM>, which may be <NUM> feet or more, and spaced apart from each other a short distance. Rotor sections <NUM> may be of various lengths, such as <NUM> to <NUM> inches. Radial bearings <NUM> locate between adjacent ends of the rotor sections <NUM>. Bearings <NUM> frictionally engage the inner diameter of stator <NUM> to prevent their rotation.

Each rotor section <NUM> has a number of permanent pole magnets <NUM> mounted circumferentially around shaft <NUM>. Pole magnets <NUM> are indicated by dotted lines in <FIG>, and may be stacked in segments for each rotor section <NUM>. Each segment has an array of pole magnets <NUM> spaced around shaft <NUM>. In this example, there are four segments 56a, 56b, 56c and 56d, each segment containing pole magnets <NUM> encircling shaft <NUM>. The array of four segments 56a, 56b, 56c and 56d extends approximately a full length of each rotor section <NUM>. The lower ends of the pole magnets <NUM> in each segment 56a, 56b and 56c may abut the upper ends of the pole magnets <NUM> in the next lower segment. There are at least two pole magnets <NUM> in each segment 56a, 56b, 56c and 56d, and they are separated from adjacent pole magnets <NUM> by non-magnetic spacers <NUM> in this example. The spacers <NUM> in each segment 56a, 56b, 56c and 56d may have the same axial dimension as the pole magnets <NUM> in the same segment.

Referring to <FIG>, in this example, there are four pole magnets <NUM> in each segment 56a, 56b, 56c and 56d, but other numbers are feasible, such as two, eight or other numbers. There are also four spacers <NUM> in each segment 56a, 56b, 56c and 56d, each located between two adjacent pole magnets <NUM>. In this example, pole magnets <NUM> and spacers <NUM> are mounted to the outer surface of an inner sleeve <NUM> that is keyed or affixed to shaft <NUM> for rotating shaft <NUM>. Pole magnets <NUM> and spacers <NUM> may attach to inner sleeve <NUM> in various manners, such as by epoxy or an adhesive. Optionally, a protective outer sleeve <NUM> encloses the array of magnets <NUM>, <NUM> and rotates with each rotor section <NUM>. Shaft <NUM> and inner sleeve <NUM> are normally of a magnetically permeable material, such as a steel. Outer sleeve <NUM> is non-magnetic and may be of different materials. An annular gap exists between outer sleeve <NUM> and the inner diameter of stator <NUM>.

Each rotor section <NUM> is secured to shaft <NUM> for rotating shaft <NUM>, typically by a key <NUM> engaging a mating slot or keyway <NUM>. The same keyway <NUM> may extend along shaft <NUM> through all of the rotors sections <NUM>.

Referring to <FIG>, lower motor <NUM> has a stator adapter <NUM> that secures to a motor housing (not shown) and may be considered to be a part of the lower motor housing. A rotatable drive shaft <NUM> extends through the lower motor housing. Lower motor <NUM> will have a stator and rotor sections with pole magnets, not shown but the same as upper motor <NUM>. A lower shaft keyway <NUM> extends along a length of lower shaft <NUM> for causing rotation of lower shaft <NUM> by the rotor sections of lower motor <NUM>. In this example, upper shaft <NUM> has a lower splined end <NUM> with external splines <NUM>. External splines <NUM> are spaced around the circumference of lower splined end <NUM>. A tubular coupling <NUM> has internal splines <NUM> that slide axially over and mesh with external splines <NUM>.

In this embodiment, the array of external splines <NUM> has an irregularity <NUM> formed therein that is at a controlled orientation relative to upper shaft keyway <NUM> and thus the pole magnets <NUM> (<FIG>). The controlled orientation may consist of axially aligning irregularity <NUM> with keyway <NUM>, as shown. Keyway <NUM> is at a known orientation relative to pole magnets <NUM>, and in this example, it is on a radial line passing through a center point of one of the pole magnets <NUM>, as shown in <FIG>.

Coupling <NUM> has a mating irregularity <NUM> that will slidingly receive external spline irregularity <NUM>. Irregularities <NUM>, <NUM> may be a variety of structures that prevent external splines <NUM> from sliding into engagement with coupling internal splines <NUM>, unless irregularities <NUM>, <NUM> are axially aligned with each other. In this example, upper shaft irregularity <NUM> is a space or gap between two external splines <NUM> where another external spline <NUM> would normally exist. The spacing between the remaining external splines <NUM> is uniform and conventional. Coupling internal irregularity <NUM> is similarly a space or gap where another internal spline <NUM> would normally exist. The spacing between the remaining internal splines <NUM> is conventional. The radius from axis <NUM> to coupling internal irregularity <NUM> is less than the radius from axis <NUM> to the tips of external splines <NUM>, thus one of the uniform external splines <NUM> could not slide into coupling irregularity <NUM>.

Lower shaft <NUM> has an upper splined end <NUM> configured the same as upper shaft lower splined end <NUM> in this example. A lower shaft irregularity <NUM> also comprises a space or gap between two external splines <NUM> of lower shaft <NUM> where another external spline <NUM> would normally exists. The spacing between the remaining lower shaft external splines <NUM> is uniform and conventional. The radius from axis <NUM> to coupling internal irregularity <NUM> is less than the radius from axis <NUM> to the tips of lower shaft external splines <NUM>, thus one of the lower shaft external splines <NUM> could not slide into coupling irregularity <NUM>. Coupling <NUM> will slide over lower shaft upper splined end <NUM> only if lower shaft irregularity <NUM> is axially aligned with coupling irregularity <NUM>.

Coupling internal splines <NUM> may have a length less than the combined lengths of upper shaft external splines <NUM> and lower shaft external splines <NUM>. A coil spring <NUM> may be employed to urge coupling <NUM> toward a central position, as shown. When coupling <NUM> is in engagement with both upper shaft splined end <NUM> and lower shaft splined end <NUM>, upper shaft keyway <NUM> will be in axial alignment with lower shaft keyway <NUM>. Pole magnets <NUM> (<FIG>) will be in the proper alignment with the pole magnets of lower motor <NUM>.

A connector assembly <NUM> connects upper motor housing <NUM> (<FIG>) with the lower motor housing. Connector assembly <NUM> may be a variety of types, including bolted types, as shown, or threaded rotatable sleeves (not shown). In this example, connector assembly <NUM> includes an upper motor base <NUM> which is secured to a stator adapter <NUM> of upper motor housing <NUM> with bolts <NUM>. Alternately, upper motor base <NUM> could have external threads that engage internal threads in upper motor housing <NUM>. Three upper motor wires <NUM> (only one shown) for the three electrical phases of motors <NUM>, <NUM> extend downward through passages in upper motor base <NUM>. Each upper motor wire <NUM> has an electrical connector <NUM>, which is illustrated schematically, on a lower end. Upper motor base <NUM> has an axial bore <NUM> in which coupling <NUM> is located.

Connector assembly <NUM> also includes a lower motor head <NUM> that is secured to stator adapter <NUM> of the lower motor housing with bolts <NUM>. Alternately, lower motor head <NUM> could have external threads that engage internal threads in lower motor housing stator adapter <NUM>. Lower motor wires <NUM> (only one shown), one for each phase, have electrical connectors <NUM> that electrically connect with upper motor electrical connectors <NUM>. Lower motor head <NUM> secures to upper motor base <NUM> with bolts <NUM> in this example.

To connect motors <NUM>, <NUM>, coupling <NUM> will be positioned over one of the shafts <NUM>, <NUM>, such as upper shaft splined end <NUM>, which requires coupling irregularity <NUM> to be axially aligned with upper shaft irregularity <NUM>. Lower motor <NUM> will be positioned in alignment with upper motor <NUM>. Before abutting lower motor head <NUM> with upper motor base <NUM>, a lower portion of coupling <NUM> will be visible. Technicians will manually rotate lower motor shaft <NUM> until lower motor shaft irregularity <NUM> aligns with coupling irregularity <NUM>. Technicians then slide motors <NUM>, <NUM> toward each other, which causes lower shaft splined end <NUM> to slide into engagement with internal splines <NUM> of coupling <NUM>. The technicians will connect motor wires <NUM>, <NUM>, then abut upper motor base <NUM> with lower motor head <NUM> and connect them together with bolts <NUM>.

After running ESP <NUM> into the well, three phase AC power will be supplied to stator windings <NUM> and the windings in lower motor <NUM> via motor wires <NUM>, <NUM>. A variable speed drive at the surface of the well may vary the frequency of the power for startup and other reasons. The current in windings <NUM> results in magnetic flux being created that revolves around stator <NUM>. The revolving electromagnetic field interacts with the magnetic flux of pole magnets <NUM>, causing rotor sections <NUM> and upper shaft <NUM> to rotate. At the same time, the current in the windings of lower motor <NUM> results in magnetic flux being created that revolves around the stator in lower motor <NUM>, causing its rotor sections and lower shaft <NUM> to rotate. Because of the connection of upper and lower shafts <NUM>, <NUM> with coupling <NUM>, the shafts rotate in unison. The coupling irregularity <NUM> and shaft irregularities <NUM>, <NUM> assure that the pole magnets <NUM> of upper motor <NUM> are aligned with the pole magnets of lower motor <NUM>.

As an alternative, one of the shafts <NUM>, <NUM> could be permanently secured to coupling <NUM>, as by welding, in a controlled orientation with the pole magnets. For example, coupling <NUM> could be welded to upper shaft <NUM> during manufacturing with upper shaft keyway <NUM> axially aligned with coupling irregularity <NUM>. During connection of lower motor <NUM> with upper motor <NUM>, lower shaft would be manually rotated to align lower shaft irregularity <NUM> with coupling irregularity <NUM> before insertion.

<FIG> and <FIG> illustrates a second embodiment, and components that are the same or similar to those in the first embodiment may have the same reference numerals, except for the prefix of a "<NUM>". Upper motor shaft <NUM> and lower motor shaft <NUM> have external splines <NUM>, <NUM> that are uniformly spaced apart without irregularities such as irregularities <NUM>, <NUM> (<FIG>). Coupling internal splines <NUM> are uniformly spaced apart without an irregularity such as irregularity <NUM> (<FIG>). An upper shaft spline keyway <NUM> is formed between two of the upper shaft external splines <NUM> in a controlled orientation relative to the pole magnets of upper motor <NUM> (<FIG>). For example, upper shaft spline keyway <NUM> may be axially aligned but not joining with upper shaft rotor section keyway <NUM> (<FIG>). Upper shaft spline keyway <NUM> extends through the external splines <NUM> to the lower end of the splined end of upper shaft <NUM>. Similarly, a lower shaft spline keyway <NUM> is formed on lower shaft <NUM> in a controlled orientation relative to the pole magnets of lower motor <NUM> (<FIG>). Lower shaft spline keyway <NUM> may be axially aligned with but not joining the lower shaft rotor section keyway <NUM> (<FIG>).

Coupling <NUM> has a similar coupling keyway <NUM> that extends substantially the full length of coupling <NUM>. A single coupling key <NUM> extends through the mating upper shaft spline keyway <NUM> and coupling keyway <NUM> and through the mating lower shaft spline keyway <NUM> and coupling keyway <NUM>. Key <NUM> and keyways <NUM>, <NUM> and <NUM> assure that the pole magnets of upper and lower motors <NUM>, <NUM> are aligned when connected.

Technicians connecting motors <NUM>, <NUM> in the technique of the second embodiment will first slide coupling <NUM> onto one of the shafts, such as upper shaft <NUM> with upper shaft spline keyway <NUM> aligned with coupling keyway <NUM> and key <NUM> inserted. The technicians manually rotate the other shaft, such as lower shaft <NUM>, until lower shaft spline keyway <NUM> aligns and receives key <NUM>. Kay <NUM> may be prevented from axial movement once motors <NUM>, <NUM> are connected by terminated ends of shaft spline keyways <NUM>, <NUM>.

Alternatively, rather than having a coupling key extending the full length of coupling <NUM> to engage both shafts <NUM>, <NUM>, one end of coupling <NUM> could be permanently attached to one of the shafts in a controlled orientation relative to the pole magnets of one of the motors.

<FIG> illustrates a third embodiment, with the reference numerals of similar components to the first two embodiments being the same except for the prefix "<NUM>". Upper shaft <NUM> has an indicia <NUM> formed on it. Indicia <NUM> could be some type of marking, such as an arrow, or a protuberance. Upper shaft indicia <NUM> is in a controlled orientation relative to the pole magnets <NUM> (<FIG>) of upper shaft <NUM>. For example, it may be on an axial or linear alignment with upper shaft rotor section keyway <NUM> (<FIG>). Indicia <NUM> is illustrated as being adjacent and slightly above upper shaft lower splined end <NUM>, but it could be at other locations, such as on lower splined end <NUM>. Upper shaft external splines <NUM> may be conventional.

Lower shaft <NUM> also has an indicia <NUM> formed on it. Indicia <NUM> could be some type of marking, such as an arrow, or a protuberance. Lower shaft indicia <NUM> is in a controlled orientation relative to the pole magnets of lower shaft <NUM>. For example, it may be on an axial or linear alignment with lower shaft rotor section keyway <NUM> (<FIG>). Lower shaft Indicia <NUM> is illustrated as being adjacent and slightly below lower shaft lower splined end <NUM>, but it could be at other locations, such as on lower shaft splined end <NUM>. Lower shaft external splines <NUM> may be conventional.

Coupling <NUM> has one or more indicia <NUM> (two shown) on its exterior and in a position be visible in connector bore <NUM> (<FIG>) prior to connecting motors <NUM>, <NUM>. Coupling <NUM> will be inserted over one shaft end, such as upper shaft splined end <NUM>, with the coupling indicia <NUM> aligned with upper shaft indicia <NUM>. Once coupling <NUM> has been inserted over shaft splined end <NUM>, it is possible that upper shaft indicia <NUM> will no longer be visible in connector bore <NUM> (<FIG>). However, at least one of the coupling indicia <NUM> will be visible. Technicians will rotate lower shaft <NUM> until lower shaft indicia <NUM> is in axial or linear alignment with coupling indicia <NUM>, which is already aligned with upper shaft indicia <NUM>. The technicians then push lower shaft splined end <NUM> into meshing engagement with coupling <NUM> and secure motor housings <NUM>, <NUM> (<FIG>) with connector <NUM>.

Alternatively, rather than having indicia on both shafts <NUM>, <NUM>, one end of coupling <NUM> could be permanently attached to one of the shafts in a controlled orientation relative to the pole magnets of one of the motors.

<FIG> illustrate a fourth embodiment, with the reference numerals of similar components to the first three embodiments being the same except for the prefix "<NUM>". Coupling <NUM> has one end, illustrated to be an upper end, permanently connected to upper shaft <NUM> for rotation in unison. Coupling <NUM> has two orientation or cam slots 401a, 401b on its lower end. The centers of each orientation slot 401a, 401b are <NUM> degrees apart from each other. Each orientation slot 401a, 401b has side edges <NUM> that face each other and curve from a greater width apart at the entrance on the lower end of coupling <NUM> toward each other.

Side edges <NUM> of each orientation slot 401a, 401b join a guide slot portion <NUM> of each orientation slot 401a, 401b, which is linear and extends upward a selected distance. Side edges <NUM> are parallel to each other and parallel with axis <NUM> within guide slot portions <NUM>. The guide slot portions <NUM> of each orientation slot 401a, 401b are <NUM> degrees apart from each other relative to axis <NUM>. Each guide slot portion <NUM> is in a controlled orientation relative to one set of pole magnets <NUM> (<FIG>) of upper shaft <NUM>. For example, one guide slot portion <NUM> may be in axial alignment with upper shaft rotor section keyway <NUM>. The other guide slot portion <NUM> is in alignment with a set of pole magnets <NUM> that are <NUM> degrees from the first set. The two orientation slots 401a, 401b provide an appearance of an open mouth of a whale.

Coupling <NUM> has a set of internal splines <NUM>, shown by dotted lines, but they do not extend to the guide slot portions <NUM>. Internal splines <NUM> begin adjacent the lower end of upper shaft <NUM> and extend downward for a length approximately equal to a length of external spline <NUM> on lower shaft <NUM>.

Lower shaft <NUM> has two guide members <NUM> on its exterior below external splines <NUM>. Guide members <NUM> may comprise pins or other protuberances extending a short distance radially outward from the exterior surface of lower shaft <NUM>. Guide members <NUM> are <NUM> degrees apart from each other. Each guide member <NUM> is in a controlled rotational orientation relative to one set of pole magnets of lower motor <NUM>. For example, one of the guide members <NUM> may be axially aligned with the lower shaft rotor section keyway <NUM>. Each guide member <NUM> is sized for close reception within one of the coupling guide slot portions <NUM>. The axial distance from each guide member <NUM> to the upper end of external splines <NUM> is less than the axial distance from the lower ends of guide slot portions <NUM> to internal splines <NUM>.

One guide slot portion <NUM> is in a controlled rotational position relative to one set of pole magnets <NUM> (<FIG>) on upper shaft <NUM>. The other guide slot portion <NUM> is in a controlled rotational position relative to a set of pole magnets <NUM> on upper shaft <NUM> that are <NUM> degrees from the first set.

When technicians begin moving lower motor <NUM> (<FIG>) toward upper motor <NUM>, lower shaft external splines <NUM> will slide into the open end or entrance of coupling <NUM>. Guide members <NUM> will likely be initially out of alignment with guide slot portions <NUM>. As a result, they will first contact orientation slot side edges <NUM> of both orientation slots 401a, 401b, as illustrated in <FIG>. Continued movement of lower shaft <NUM> toward upper shaft <NUM> causes guide members <NUM> to slide on side edges <NUM> of each orientation slot 401a, 401b, automatically rotating lower shaft <NUM> due to the cam action created by orientation slots 401a, 401b. When guide members <NUM> first enter guide slot portions <NUM>, rotation will stop and lower shaft <NUM> will be properly oriented relative to upper shaft <NUM>. Lower shaft external splines <NUM> will be aligned with internal splines <NUM> but will not yet have engaged internal splines <NUM>. Continued forward movement causes lower shaft external splines <NUM> to enter and slide into meshing engagement with coupling internal splines <NUM>.

Unlike the first three embodiments, it is not necessary to manually rotate lower shaft <NUM> to rotationally orient it. The automatic rotational alignment occurring while moving motors <NUM>, <NUM> toward each other is an advantage because the magnetic fields of the pole magnets in the lower motor <NUM> can make manual rotation of the lower shaft difficult. Also, as rotation while connecting can generate an electrical charge, the technicians with an automatic alignment system can better position themselves away from any accidental exposure.

The various embodiments illustrate at least four different alignment means for rotationally aligning the magnetic poles of the first drive shaft with the magnetic poles of the second drive shaft prior to securing the housings of the first and second motors together. In the first embodiment (<FIG> and <FIG>), the alignment means comprises irregularities or gaps <NUM>, <NUM> in external splines <NUM>, <NUM> of the shafts <NUM>, <NUM> and an irregularity <NUM> in the coupling splines <NUM>. In the second embodiment (<FIG> and <FIG>), the alignment means comprises a key <NUM> extending through keyways <NUM>, <NUM> on the shafts <NUM>, <NUM> and a keyway <NUM> in the coupling <NUM>. In the third embodiment (<FIG>), the alignment means comprises indicia <NUM>, <NUM> on shafts <NUM>, <NUM> and indicia <NUM> on coupling <NUM>. In the fourth embodiment (<FIG>), the alignment means comprises orientation slots 401a, 401b and guide members <NUM>.

Claim 1:
An electrical submersible well pump assembly (<NUM>), comprising:
first and second motors (<NUM>, <NUM>), each having a housing (<NUM>, <NUM>), the first and second motors having first and second shafts (<NUM>, <NUM>), respectively, each of the first and second motors having a plurality of rotor sections (<NUM>), a rotor keyway (<NUM>, <NUM>) between each of the rotor sections and the shaft of each of the motors;
the second shaft having a splined end (<NUM>)with external splines (<NUM>);
a coupling (<NUM>) connected with the first shaft for rotation in unison, the coupling having internal splines (<NUM>) that engage the external splines for causing the first and second shafts to rotate in unison; and
a housing connector (<NUM>) that connects the housing of the first motor with the housing of the second motor, the housing connector having a bore (<NUM>) with the coupling located therein, characterized by:
each of the rotor sections having a plurality of circumferentially spaced permanent magnets (<NUM>), defining magnetic poles;
alignment means for (<NUM>, <NUM>) rotationally aligning the magnetic poles of the first shaft with the magnetic poles of the second shaft prior to securing the housings of the first and second motors together.