Patent Publication Number: US-2021167655-A1

Title: Surgical Instrument Motor With Increased Number Of Wires Per Phase Set And Increased Fill Factor And Corresponding Manufacturing Method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 15/951,458 filed on Apr. 12, 2018, which is a divisional of U.S. application Ser. No. 14/534,794 filed on Nov. 6, 2014, which is now U.S. Pat. No. 9,979,247 issued on May 22, 2018. The entire disclosures of the above application are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to electric motors of hand-held surgical instruments. 
     BACKGROUND 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     A hand-held surgical instrument may have various parameter requirements including weight, power, size, current loss and heat generation requirements. Producing a hand-held surgical instrument with decreased weight, increased power output and/or torque, decreased size, reduced current loss and decreased heat generation can be difficult due to the relationships between these parameters. For example, as power output of a motor increases, heat generated by the motor generally increases. As another example, as size of a motor decreases, power output of the motor typically decreases. 
     A brushless direct current (DC) motor is capable of operating at higher efficiency levels and at higher speeds with reduced heat generation than a motor with brushes due to no mechanical contact between rotating and stationary components of the brushless DC motor. A brushless DC motor can include a rotor and a stator. The rotor has a shaft and a hub assembly with a centrally located magnetic structure. The stator has one or more coils. The coils are mounted on a centrally located support sleeve and proximally and distally located support rings. The rotor is held in a cavity of the stator and in a position relative to the support sleeve and support rings such that the rotor does not contact the support sleeve, the coils, and/or the support rings. Electrical current is supplied to the coils, which causes the rotor to rotate relative to the stator due to interactions between (i) magnetic fields generated by the coils and (ii) a magnetic field produced by the magnetic structure of the rotor. The rotor rotates axially in the support sleeve, the coils, and the support rings. 
     Brushless DC motors (hereinafter referred to as “motors”) convert electrical power into mechanical power or torque. During this conversion, losses can arise that limit mechanical power, torque and speed of the motors. These losses can generally be classified into three categories: (1) load sensitive losses dependent on generated torque; (2) speed sensitive losses dependent on motor speed; and (3) pulse-width modulation (PWM) losses dependent on quality of a current supply employed to drive the motors. 
     The load or torque sensitive losses are generally limited to winding losses, which are proportional to a product of (i) a square of an amount of current through windings of a motor and (ii) a resistance of the windings. Speed sensitive losses (e.g., core or iron losses due to Eddy currents and hysteresis, windage and friction) act as a velocity dependent torque opposite an output torque of a motor. PWM losses are attributable to Eddy currents in a magnetic structure caused by the current supply. Eddy currents are a phenomena caused by a variation of a magnetic field through an electrically conductive medium. In the case of brushless DC motors, the coils of the stator experience a change in a magnetic field. The rotation of the rotor and current variations in the coils induce a voltage in the coils, which results in the creation of Eddy currents. Increased Eddy currents can increase thermal energy output of a motor, especially when operating at high speeds. 
     SUMMARY 
     A motor for a surgical instrument is provided and includes a rotor and a stator. The rotor includes a shaft and a magnet. The stator includes (i) a cavity in which the rotor is disposed, and (ii) a coil assembly. The coil assembly includes multiple phase sets. The phase sets include multiple sets of wires. Each of the phase sets includes multiple coils and corresponds to a respective one of the sets of wires. The coils in each of the phase sets are at respective positions about the rotor. One of the sets of wires includes at least three wires. The stator causes the rotor to axially rotate a surgical tool of the surgical instrument based on current received at the sets of wires. 
     In other features, a method of manufacturing a motor for a surgical instrument is provided. The method includes: providing a rod with multiple sets of pins; and wrapping multiple sets of wires on the sets of pins to form multiple phase sets on the rod to provide a coil body. Each of the phase sets includes multiple coils and corresponds to a respective one of the sets of wires. The method further includes: removing the sets of pins from the rod; compressing the coil body a first time; inserting a portion of the coil body in a sleeve; connecting the phase sets in series; applying current to the phase sets to fuse the sets of wires a first time; compressing the coil body a second time; applying current to the phase sets to fuse the sets of wires a second time; removing the coil body from the rod; and inserting the coil body into a motor housing of the surgical instrument. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective environmental view of a surgical instrument incorporating a brushless sensorless DC motor in accordance with an embodiment of the present disclosure. 
         FIG. 2  is a side perspective view of a portion of the surgical instrument of  FIG. 1 . 
         FIG. 3  is a side exploded view of a portion of the surgical instrument of  FIG. 1 . 
         FIG. 4  is an axial cross-sectional view of a motor and a portion of a motor housing in accordance with an embodiment of the present disclosure. 
         FIG. 5  is a radial cross-sectional view of a multi-phase set coil assembly of a motor in accordance with an embodiment of the present disclosure. 
         FIG. 6  is a sectional view of compressed and fused wires of coils of a motor in accordance with an embodiment of the present disclosure. 
         FIG. 7  illustrates a method of constructing a multi-phase set coil assembly of a motor in accordance with an embodiment of the present disclosure. 
         FIG. 8  is a side perspective view of a mandrel having a separation layer in accordance with an embodiment of the present disclosure. 
         FIG. 9  is a perspective view of a portion of the mandrel illustrating sets of pins inserted in the mandrel in accordance with an embodiment of the present disclosure. 
         FIG. 10  is a side perspective view of the mandrel mounted on a rotating device in accordance with an embodiment of the present disclosure. 
         FIG. 11  is a block and side perspective view of a wire delivery system illustrating placement of wires relative to the mandrel and some of the pins in accordance with an embodiment of the present disclosure. 
         FIG. 12  is a perspective view illustrating wrapping wires of a first coil of a first phase set of the multi-phase set coil assembly in accordance with an embodiment of the present disclosure. 
         FIG. 13  is a perspective view illustrating wrapping wires of a second coil of the first phase set of the multi-phase set coil assembly of  FIG. 12 . 
         FIG. 14  is a side perspective view of the multi-phase set coil assembly mounted on the mandrel in accordance with an embodiment of the present disclosure. 
         FIG. 15  is a perspective environmental view illustrating heat stripping and coating of ends of sets of wires of the multi-phase set coil assembly in accordance with an embodiment of the present disclosure. 
         FIG. 16  is a perspective view of the multi-phase set coil assembly mounted on the mandrel without a set of pins and in accordance with an embodiment of the present disclosure. 
         FIG. 17  is a perspective view of the multi-phase set coil assembly mounted on the mandrel having a portion of the multi-phase coil assembly wrapped and compressed in accordance with an embodiment of the present disclosure. 
         FIG. 18  is a perspective view of the multi-phase set coil assembly mounted on the mandrel having a second set of pins removed in accordance with an embodiment of the present disclosure. 
         FIG. 19  is a perspective view of the multi-phase set coil assembly mounted on the mandrel having a second portion of the multi-phase set coil assembly wrapped and compressed in accordance with an embodiment of the present disclosure. 
         FIG. 20  is a perspective view of the multi-phase set coil assembly mounted on the mandrel illustrating a thermocouple and a holding layer over a center of the multi-phase set coil assembly in accordance with an embodiment of the present disclosure. 
         FIG. 21  is a perspective view of the multi-phase set coil assembly mounted on the mandrel illustrating a protection layer being applied over a center portion of the multi-phase set coil assembly in accordance with an embodiment of the present disclosure. 
         FIG. 22  is a perspective view of the multi-phase set coil assembly mounted on the mandrel illustrating a portion of the multi-phase set coil assembly inserted in a sleeve in accordance with an embodiment of the present disclosure. 
         FIG. 23  is a perspective view of the multi-phase set coil assembly, the mandrel, and the sleeve inserted in a base of a press in accordance with an embodiment of the present disclosure. 
         FIG. 24  is a perspective view of the press in a closed fully compressed state in accordance with an embodiment of the present disclosure. 
         FIG. 25  is a cross-sectional view of a wire in accordance with an embodiment of the present disclosure. 
     
    
    
     In the drawings, reference numbers may be reused to identify similar and/or identical elements. 
     DESCRIPTION 
     Surgical instruments are disclosed below that include brushless sensorless DC motors. The brushless sensorless DC motors have increased power output and/or torque, reduced current losses including Eddy current losses, reduced coil resistances, increased fill factors (or coil slot fill levels), and reduced heat generation than motors of traditional surgical instruments. These features are provided without increasing overall exterior dimensions of the brushless sensorless DC motors. These features are provided while reducing a number of stator support components and thus simplifying an interior of a motor housing. Example methods are also disclosed for manufacturing the brushless sensorless DC motors. 
       FIG. 1  shows a surgical instrument  10  incorporating a brushless sensorless DC motor  12  (hereinafter referred to as “the motor”). The surgical instrument  10  includes a motor housing  14  that includes the motor  12 . Examples of the motor  12  are shown in at least  FIG. 4 . The surgical instrument  10  may be used, for example, to mill, drill, shape and dissect bone and other tissue. The surgical instrument  10  is shown operatively associated with a patient  16 . As an example, the surgical instrument  10  may be used to perform various procedures (e.g., a craniotomy). The surgical instrument  10  is not limited to any particular surgical procedures and/or applications. These applications may include dissecting bone or other tissue. Additional example applications include: 1) arthroscopy—orthopaedic applications; 2) endoscopic—gastroenterology, urology, and soft tissue applications; 3) neurosurgery—cranial, spine, and otology applications; 4) small bone—orthopaedic, oral-maxiofacial, ortho-spine, and otology applications; 5) cardio thoracic—small bone sub-segment applications; 6) large bone—total joint and trauma applications; and 7) dental applications. 
       FIGS. 2-3  show portions  20 ,  22  of the surgical instrument  10  of  FIG. 1 . The surgical instrument  10  includes a collet  24 , the motor housing  26 , a connector  28 , and a cable  30 . The collet  24  is configured to hold a surgical tool (e.g., surgical tool  32  is shown in  FIG. 1 ). The surgical tool may be a cutting tool and/or dissection tool (e.g., a tool that includes a surgical bur). The motor housing  26  connects to the collet  24  and the cable connector  28 . The motor  12  is mounted in the motor housing  26  and axially rotates the surgical tool based on power, current and/or voltage supplied to the motor via the cable  30 . A portion of the surgical tool may extend through the collet and connect to a shaft of the motor. An example shaft is shown in  FIG. 4 . In operation, the motor  12  provides torque to axially rotate (or spin) the surgical tool. 
       FIG. 4  shows an axial cross-sectional view of (i) a portion  40  of the motor housing  26  of  FIGS. 2-3 , and (ii) the motor  12 . The motor housing  26  includes laminations  42 . The laminations  42  are cylindrically-shaped and are mounted on interior walls  44  of the motor housing  26  adjacent and opposing one or more magnets  58  (or a center portion  46  of the motor  12 ). The laminations  42  channel, direct or steer a magnetic field generated by the one or more magnets  58  and electrical currents in a coil body  48  away from the housing  26 . This directs magnetic flux provided by the magnetic field of the one or more magnets  58  through the coil body  48  of the motor  12 , as opposed to the magnetic flux being received by the motor housing  26 . The motor  12  includes a rotor  50  and a stator  52 . 
     The rotor  50  includes a shaft  56  on which the one or more magnets  58  are mounted. The shaft  56  may be connected to a surgical tool (e.g., the surgical tool  32  of  FIG. 1 ). The surgical tool may be axially rotated based on axial rotation of the shaft  56 . The shaft  56  and the magnets  58  are axially rotated within the stator  52 . The one or more magnets  58  may include, for example, high-energy density rare-earth magnetic materials. A press ring  60  may be mounted on the shaft  56  and incorporated to balance spinning motion of the shaft  56 . The shaft may ride on bearing sets (not shown) proximally and distally located in the motor housing  26 . 
     The stator  52  may include the coil body  48  (sometimes referred to as a multi-phase set coil assembly) with a predetermined number of coils (e.g., six coils or two coils per phase set). Examples of the coils are shown in  FIGS. 5-6, 13-14, and 16-23 . Although the motors disclosed herein are primarily described with respect to a 3-phase set coil assembly having 6 coils, the motors may have any number of phase sets and/or coils per phase set. A 3-phase set refers to coils of each phase set being at respective axial phases (or axial positions) around the rotor  50 . Each of the phase sets may be at 120° intervals around the rotor  50 . As shown in  FIG. 4 , the stator  52  includes the coil body  48  and does not include proximal, central and/or distally located support members. This is due to the rigid structure of the coil body  48 , which is further described below. The coil body  48  is held in place within the laminations  42  and the interior walls  44 . This is unlike traditional coil bodies that have proximal, central and distal support members (e.g., support rings extending within the coil bodies). 
     The coil body  48  has a distal end  62  and a proximal end  64 . Although not shown in  FIG. 4 , sets of wires extend from the proximal end  64  and receive power from a power source via a cable (e.g., the cable  30  of  FIG. 3 ). The sets of wires are shown in  FIGS. 14, 16-22 and 24 . The proximal end  64  may be held between the motor housing  26 . The coil body  48  and thus the coils of the coil body  48  are sized to fill a high-percentage of a cavity  70  of the coil body  48  between the laminations  42  and the magnets  58  while not contacting the laminations  42  and the magnets  58 . A first gap G 1  exists between the laminations  42  and the coil body  48  and may be filled with a dielectric material for electric isolation. A second gap G 2  (or air gap) exists between the coil body  48  and the magnets  58 . A first inner diameter D 1  of the coil body  48  at the distal end  62  may be, for example, 6-6.5 millimeters (mm). A second inner diameter D 2  of the coil body  48  in the center portion  46  and opposing the magnets  58  may be, for example, 7-8.2 millimeters (mm). A first outer diameter D 3  of the coil body  48  in the center portion  46  may be, for example, 10-11 mm. A second outer diameter D 4  of the coil body  48  at the proximal end  64  may be, for example, 12-14 mm. 
       FIGS. 5-6  show radial cross-sectional views of a coil body (or multi-phase set coil assembly)  80  of a motor (e.g., the motor  12  of  FIG. 1 ). The coil body includes multiple coils and may replace the coil body  48  of  FIG. 4 . Each coil of the coil body includes sets of wires. Some of the wires are designated  82 . Each of the wires includes a conductive filament and a thin outer insulation layer to prevent electrical connections between the wires. The number of wires in each of the sets of wires and cross-sectional diameters (an example cross-sectional diameter D 5  is shown in  FIG. 6 ) of the wires affects a fill factor of the coil body. The fill factor refers to a percentage of conductive material (e.g., copper) contained within a volume (or envelope) of the coil body. An example cross-sectional view of a wire  90  including a filament  92 , an insulation layer  94  and a bonding layer  96  is shown in  FIG. 25 . 
     The higher the fill factor, the more conductive material within a given area. Also, the higher the fill factor or the more conductive material per set of wires, the lower the resistances of the sets of wires. In general, the more conductive material, the more power output and/or torque produced by a corresponding motor. Also, as the number of wires per set increases, for a given fill factor, the amount of Eddy current losses decreases. On the other hand, as the fill factor increases, the amount of Eddy current losses increases. In addition, there are structural and manufacturing limits as to how small a cross-sectional diameter of the wires can be and how many wires can be manufactured, handled, and wrapped, to form the coils. For example, the smaller the cross-sectional diameter of the wires, the more likely that the wires are deformed during manufacturing. The smaller the cross-sectional diameter of each of the wires, the more wires can be wrapped to fill a given volume. Although the more wires the lower the fill factor. This is due to the volume associated with the insulation layers of the wires. 
     Thus, to maximize power and torque output of a motor, minimize size of the motor, minimize current losses, prevent deforming of wires of the motor, and assure the motor is an efficient and structurally reliable motor, certain parameters of a coil body are selected to be within predetermined ranges. In addition, the coil body is constructed to minimize number of coil supports and to maximize a fill factor for a given volume of the coil body. As a first example, each set of wires may include a predetermined number of wires (e.g., 10-20 wires). In one embodiment, each of the sets of wires includes 15-18 wires. In another embodiment, each of the sets of wires includes 17-18 wires. As another example, the cross-sectional diameter of the wires may be 0.09-0.14 mm. As yet another example, a combined thickness of an insulation layer and a bonding (or adhesive) layer of each of the wires may be, for example, 10-20 micrometers (μm). Each of the wires has an insulation layer and may have a bonding (or adhesive layer). The purpose of these layers is further described below. An example cross-sectional diameter D 6  of the wire  90  and a corresponding combination thickness T 1  of the insulation layer  94  and the bonding layer  96  are shown in  FIG. 25 . 
     In one embodiment, the wires are 38 American wire gauge (AWG38) wires, where a combination thickness of an insulation layer and a corresponding bonding layer of each of the wires is 15 μm. As still another example, the fill factor may be (i) 58-65% if bonding layers or a bonding agent is used, or (ii) 66-74% if bonding layers or a bonding agent is used. A bonding agent or varnish may be applied to the insulation layers to provide the bonding layers. 
     Incorporating sets of wires, where each of the sets of wires has a number of wires within a predetermined range (e.g., 15-18) and the cross-sectional diameters of the wires are within a second predetermined range (e.g., 0.10-0.12 mm), provides a fill factor with an increased level of conductive material, reduced phase set resistances, reduced current losses, and as a result reduced heat generated. This is especially true during high-load and/or high-speed operating conditions. Under low-load and/or low-speed operating conditions, Eddy current losses are minimized by providing a motor with numbers of wires, in each of the sets of wires, being in one of the predetermined ranges. Eddy current losses increase as fill factor increases. 
     The sets of wires are compressed and fused to each other, as further described below with respect to the method of  FIG. 7 , to increase a fill factor of the coils. A bonding agent may be applied to the wires prior to and/or during wrapping, compressing and/or fusing tasks associated with manufacturing of the coil body. The bonding agent may be used to aid in fusing the wires together to provide a rigid structure that has minimal flex during high-speed spinning. In one embodiment, a bonding agent is not used. The compression and fusing of the wires allows for the coil body not to be supported centrally and/or at proximal and/or distal ends by support members. Removal of proximal, distal and centrally located support members allows for additional conductive material to be incorporated in a same size volume. This allows for additional wrappings of the wires and/or an increased number of wires per set of wires to be used in the coils of the coil body. 
     The coil bodies (or coil assemblies) disclosed herein may be manufactured using the method of  FIG. 7 .  FIG. 7  shows a method of constructing a multi-phase set coil assembly of a motor. Although the following tasks are primarily described with respect to the implementations of  FIGS. 1-6 , the tasks may be easily modified to apply to other implementations of the present disclosure. The tasks may be iteratively performed. 
     The method may begin at  200 . At  202 , a press  100  (shown in  FIG. 24 ) is pre-heated to a predetermined temperature for a predetermined period. The press  100  may be in a form of a clam shell having a base  102  (or clam shell bottom) and a compression block  104  (or clam shell top). The predetermined temperature may be, for example 200° C. The predetermined period may be, for example, 2 hours. 
     At  204 , a separation layer  106  may be applied to a lubricated mandrel  108  (or other lubricated cylindrical rod), as shown in  FIG. 8 . In one embodiment, step  204  is skipped and the separation layer  106  is not applied to the mandrel  108 . The mandrel  108  may be cylindrically shaped and include two sets of holes  110 ,  112 . Each of the sets of holes includes a predetermined number of holes (e.g. 6 holes per set). The holes  110 ,  112  in each of the sets of holes  110 ,  112  are evenly distributed around the mandrel  108  at 60° increments (or intervals). Each set of holes may be perpendicular to a central longitudinal axis of the mandrel  108  or at other angles (e.g. 30-60° degrees) relative to the central longitudinal axis such that the holes angle outward toward proximal and/or distal ends of the mandrel  108 . The separation layer  106  may be applied to the mandrel  108  with an adhesive side of the separation layer  106  facing outward away from the mandrel  108  and a non-adhesive side of the separation layer  106  facing the mandrel  108 . As an example, the separation layer  106  may include a polyimide film layer and an adhesive layer. The adhesive layer providing the adhesive side of the separation layer  106 . 
     At  206 , two sets of pins  118 ,  120  are inserted in the holes  110 ,  112  in the mandrel  108 . This includes puncturing holes in the separation layer  106  at the holes  110 ,  112  in the mandrel  108 .  FIG. 9  shows the pins  118 ,  120  in the holes  110 ,  112 . The pins  118 ,  120  while in the holes  110 ,  112  extend radially outward and provide wrapping points for sets of wires, as further described below. 
     At  208 , the mandrel  108 , with the separation layer  106  and the pins  118 ,  120 , is mounted on a rotating device  130  via a mounting bracket  132 . As an example, the rotating device  130  may include a motor  134 , a rotary chuck  136 , a control module  138  and a counter  140 , as shown in  FIG. 10 . The mandrel  108  is held by the mounting bracket  132 , which is rotated via the rotary chuck  136 . The mandrel  108  may be connected to the mounting bracket  132  via a screw  142  that extends through a portion of the mounting bracket  132  and into a first end  144  of the mandrel  108 . The motor  134  may spin the rotary chuck  136 . This may be controlled by the control module  138  and based on a count indicated by the counter  140 . The control module  138  may radially rotate the mandrel  108  a predetermined number of times when forming each coil of a coil assembly. The control module  138  may stop rotating the mandrel  108  when the counter  140  reaches the predetermined number of times. This rotation is performed as described below at  212 . 
     At  210 , a first (or current) set of wires (e.g., wires  148 ) are grouped together and aligned with two pins  150 ,  152  (one pin from each of the sets of pins  118 ,  120 ) on the mandrel  108 . An example of this is shown in  FIG. 11 .  FIG. 11  shows a wire delivery system  154 . The wire delivery system  154  is provided as an example and may be replaced with another wire delivery system. The wire delivery system  154  includes spools  156 , spool tensioners  158 , and a support bracket  160 . A first end  161  of the wires may be knotted together to provide a knot  162  and held via, for example, tape  164  to the first end  144  of the mandrel  108 . The first end  161  of the wires may be labeled “x in” with a tag to indicate that this is an input end (or end that receives power) in the current set of wires, where x identifies the number of the sets of wires to be included in the coil assembly. The wires may be wound respectively on the spools  156  and extend from the spools  156  to the mandrel  108 , where the wires are then grouped together and knotted as shown. 
     The spools  156  may be mounted on the support bracket  160 . Each of the spools  156  may have and/or be connected respectively to the spool tensioners  158  to provide uniform and/or predetermined levels of tension on the wires. In one embodiment, the spool tensioners  158  provide a same amount of tension on each of the wires. In another embodiment, the spool tensioners  158  provide different levels of tension on the wires. The spool tensioners  158  may be connected to the spools via respective shafts  166 . In addition or as an alternative to the spool tensioners  158 , post-spool tensioners  157  may be used to “squeeze” down on the wires as the wire comes off the spool. The post-spool tensioners  157  may be located between the spools and the mandrel  108 . Friction provided by the squeezing of the wires provides tension as the wires are pulled off the spools  156 . When the spool tensioners  158  are not used and the post-spool tensioners  157  are used, the spools  156  are loosely mounted on the support bracket  160  to freely rotate. Although not shown, the post-spool tensioners  157  may be mounted on and/or supported by the support bracket  160 . The support bracket may be rigidly held in place relative to the rotating device  130 . 
     The attaching of the wires on the first end  144  of the mandrel  108  and the tension on the wires at a second end  168  of the mandrel  108  allows the wires to be tightly and uniformly wrapped on the mandrel  108  without kinks and/or undesigned bends in the wires. The wires may be held in a parallel extending fashion or may be twisted together. In one embodiment, the tension on the wires is controlled via the control module  138  of  FIG. 10  or other control module connected to the spool tensioners  158 . 
     At  212 , the first (or current) set of wires is wrapped around four (or first group) of the pins (two of the four pins are in the first set of pins  118  and the other two pins are in the second set of pins  120 ). The two pins in each set of pins are 120° apart from each other. The rotary chuck  136  is rotated to radially rotate the mandrel  108  and wrap the wires on the four pins and provide a first coil  170  of a first (or current) phase set of the coil assembly. The wires may be wrapped until the counter  140  reaches the predetermined number of times (or predetermined number of wraps). As an example, the predetermined number of times may be 18.  FIG. 12  shows an example of the wires wrapped on the four pins. 
     At  214 , the mandrel  108  is rotated axially 180° prior to wrapping a second coil  172  of the current phase set of the coil assembly. This may include rotating the mandrel  108  counter clockwise as seen from the mounting bracket  132  at the first end  144  of the mandrel  108 . The wires are then aligned with a second group of pins. 
     At  215 , the mandrel  108  is radially rotated to wrap the second coil of the current phase set of the coil assembly.  FIG. 13  shows the second coil  172  formed by wrapping the wires around a second group of pins. 
     At  216 , the wires are cut near the second end  168  of the mandrel  108  to provide a cut (or second) end  176 . The second end  176  of the wires may be knotted and labeled “x out” to indicate that the second end  176  is an output end of the current set of wires.  FIG. 13  shows the wires cut at the second end. 
     At  218 , if another phase set of the coil assembly is to be added to the mandrel  108 , task  220  is performed, otherwise task  222  is performed. Tasks  210 - 216  may be performed 3 times for a 3-phase set coil assembly. 
     At  220 , the mandrel  108  is rotated axially 120° to begin wrapping of a next phase set of the coil assembly and the counter  140  may be reset. This may be a counter clock wise rotation as seen at the mounting bracket  132  and/or first end  144  of the mandrel  108 . Task  220  may be performed twice for a 3-phase set coil assembly. At the completion of tasks  202 - 220 , multiple (e.g., 3) phase sets of coils may have been formed. Each of the phase sets may be 120° out-of-phase from each other. Each coil of a phase set may be 60° out-of-phase from adjacent coils and 180° out-of-phase from the other coil of the same phase set.  FIG. 14  shows a 3-phase set coil assembly  178  mounted on the mandrel  108  after completion of tasks  202 - 220 . 
     At  222 , the ends of the sets of wires are (i) stripped (by heat, chemicals or mechanical devices depending on the type of insulation used on the wire) to remove insulation layers from the ends of the wires, and (ii) coated. The ends of the set of wires may be heated to a predetermined temperature (e.g., 400° C.) to remove the insulation layers at the ends of the sets of wires. The insulation layers are not removed from the remainder of the sets of wires. The coating of the ends may include tinning the ends. In one embodiment, the ends of the sets of wires are dipped in a solder bath to coat and bind together the conductive filaments exposed due to the heat stripping. In one embodiment, the heat stripping and the coating are performed at the same time. A temperature of the coating material may be high enough (greater than or equal to a predetermined temperature) to remove the insulation layers and at the same time coat the ends of the sets of wires.  FIG. 15  shows a solder bath  180  and coated ends  179  of sets of wires  184 . In an alternative embodiment, the stripping and coating of the sets of wires  184  change a bit such that no knots in the wires are created. In one embodiment, the ends  179  of each of the sets of the wires  184  are held together via terminations (or connectors). The terminations may be connected to a printed circuit board (PCB). As another alternative, the sets of wires  184  may terminate at the PCB. 
     At  224 , a set of the pins (e.g., the second set of pins  118 ) (this conflicts with numbering in  FIG. 9  where  120  is towards long side of mandrel) is removed from the second end  168  of the mandrel  108  and a first portion  181  of the coils are wrapped and compressed.  FIG. 16  shows the second set of pins  118  removed. The other set of pins (i.e. the first set of pins  120 ) remains in the mandrel  108 . The first portion  181  of the coils may extend from a center  182  of the coils along the mandrel  108  to a distal end  183  of the coils. The first portion  181  may be wrapped, for example with a first portion  184  of a first protection layer and then compressed via a cable tie  185  (or tie wrap). The first portion  181  of the first protection layer may include paper. The cable tie  185  may be placed over the paper and around the first portion  181  of the coils and pulled tight to hold in place and compress the first portion  181  of the coils.  FIG. 17  shows the first portion  181  wrapped and compressed. 
     At  226 , the other set of the pins (e.g., the first set of pins  120 ) is removed from the first end  144  of the mandrel  108  and a second portion  186  of the coils are wrapped and compressed.  FIG. 18  shows the first set of pins  120  removed. The second portion  186  of the coils may extend from the center  182  of the coils along the mandrel  108  to a proximal end  187  of the coils. The second portion  186  may be wrapped, for example with a second portion  188  of the first protection layer and then compressed via a second cable tie  189 . The second portion  188  of the first protection layer may include paper. The second cable tie  189  may be placed over the paper and around the second portion  186  of the coils and pulled tight to hold in place and compress the second portion  186  of the coils.  FIG. 19  shows the second portion wrapped and compressed. 
     At  228 , resistances are measured. The resistances (e.g., R 1 , R 2 , and R 3  for a 3-set coil assembly) of each of the phase sets may be measured. A total resistance Rtot of the phases connected in series may be measured. Resistances between the phase sets may be measured. Resistances (e.g., R 1   m , R 2   m , R 3   m , where 1, 2, and 3 are phase set numbers and m refers to the mandrel) between each of the phase sets and the mandrel  108  may also be measured. The stated resistances may be measured for reference purposes and later verified to check whether the phase sets have been damaged during tasks  230 - 246  and/or to monitor changes in the resistances due to performing tasks  230 - 246 . 
     At  230 , the first protective layer and the cable ties  185 ,  189  are removed from the coils. At  231 , a holding layer  190  is applied to a center portion and over an exterior (or outer surface) of the coils to hold the coils in place. The holding layer  190  may include a polyimide film. This is shown in  FIG. 20 . 
     At  232 , a thermocouple  192  and a second protection layer  193  is applied to the coils (or coil body  194 ). The thermocouple  192  is applied to monitor a temperature of the coils during compression and/or fusing of the coils, as performed in the following tasks. The second protection layer  193  may include a polyimide film and prevent scraping of the wires of the coils. As an example, the temperature may be monitored by the control module  138  of  FIG. 10  or by another control module. In the following tasks, if the temperature, as indicated by the thermocouple  192 , exceeds a predetermined temperature, compression and/or fusing may be stopped and/or current applied to the coils may be decreased. Power and/or current supplied to the coils may be provided via a power source  233  (shown in  FIG. 10 ), which may be controlled via the control module  138  or other control module. The power source  233  may be directly connected to the coils or may be connected to the coils via the control module. 
     The thermocouple  192  may be applied to any part of the coils and/or connected to the control module  138  (or other control module). The thermocouple  192  may be applied to the proximal end of the coil body  194  to not interfere with compression of the coil body  194  during the following tasks. The thermocouple  192  may be applied during task  231  or during another task. More than one thermocouple may be applied and monitored. 
       FIG. 21  shows the second protection layer  193  applied on the distal and/or center portions of the coils.  FIG. 22  shows the second protective layer  193  applied to (i) distal and center portions of the coils, and (ii) a portion of the proximal portion of the coils. Although not shown, the second protection layer may cover all of the proximal portion of the coils. The second protective layer  193  is applied over an exterior (or outer surface) of the coils. 
     At  234 , the distal and center portions of the coils and the first end  144  of the mandrel  108  are slid into a sleeve. The sleeve may be ‘C’-shaped and formed of, for example, stainless steel. The sleeve may be positioned on the coils based on final predetermined dimensions of the coils. As an example, the sleeve may be slid up to the proximal end (or proximal portion) of the coil and not slide over the proximal end of the coils. This is because the proximal end of the coils may not be compressed or may be minimally compressed during the following tasks. Thus, the proximal end of the coils may have a larger outer diameter than outer diameters of the distal and center portions of the coils. This may be based on interior dimensions in a motor housing in which the coils are to be placed. Applying of the sleeve may at least partially compress the distal and center portions of the coils.  FIG. 22  shows an example of a ‘C’-shaped sleeve  195  on distal and center portions of coils. 
     At  236 , the phase sets are connected in series and a predetermined amount of current is applied to the phase sets to pre-fuse the wires together. As an example, 20 amperes (A) of DC current may be applied to the phase sets to heat and fuse the wires. 
     At  238 , the coils, the sleeve, and the mandrel  108  are placed in and/or pushed in the base  102  of the press  100 . The sleeve may be placed in the base  102 , such that an opening (or mouth)  239  of the sleeve faces upward and/or out of the base  102  and can be seen from a top of the base  102 . This is shown in  FIG. 23 . Some of the inner dimensions of the base  102  match or are similar to outer dimensions of the coils and sleeve. The base  102  may be clam-shaped or ‘C’-shaped, as shown, and has an opening through which the coils, sleeve, and mandrel  108  are provided. Due to task  236 , a temperature of the coils, sleeve and/or mandrel  108  may be greater than a predetermined temperature when placed in the base  102 . 
     At  240 , the compression block  104  of the press is placed in the opening of the base  102  and over the coils, sleeve, and mandrel  108 . Some of the inner dimensions of the compression block  104  may match or be similar to exterior dimensions of the coil body. Pressure is applied on the compression block  104  and thus to the sleeve to compress the coils. The compression block  104  may be pushed down into the base  102  until a top surface  196  of the compression block  104  is (i) above a top surface  197  of the base  102  by a first predetermined amount, (ii) flush with the top surface  197  of the base  102 , or (iii) below a top surface  197  of the base  102  by a second predetermined amount. Pressure on the compression block  104  may be increased to a predetermined amount to provide a predetermined amount of compression.  FIG. 24  shows the press  100  with the compression block  104  over the coils, sleeve, and mandrel  108  and in the base  102 . The second end  168  of the mandrel  108  and the ends of the sets of wires extend out of an opening  198  on one side  199  of the press. 
     At  241 , the coils are fused a second time. Current is applied to the phase sets. The phase sets may be connected in series as in task  236  and/or may still be connected in series from task  236 . A DC current is applied to the phase sets to heat the wires to a predetermined temperature. This may be controlled via the control module  138  and/or another control module. The power may be provided via the power source  233 . The predetermined temperature may be, for example, 200° C.±10° C. The DC current may be slowly ramped up to a predetermined level of current at a predetermined rate to provide even heating of the wires. The predetermined level of current and the predetermined temperature may be maintained for a predetermined period of time. 
     At  242 , the compression block  104  is further pushed down into the base  102 . The pressure applied to the compression block  104  may be the same as or greater than the amount of pressure applied at  240 . The compression block  104  may be pushed down into the base  102  until the top surface  196  of the compression block  104  is flush with the top surface  197  of the base  102  or below a top surface  197  of the base  102  by a third predetermined amount. The third predetermined amount may be the same as or different than the second predetermined amount. 
     At  243 , if the coils, sleeve and mandrel  108  are to be rotated, task  244  may be performed, otherwise task  245  may be performed. At  244 , the compression block  104  may be removed from the base  102  and the coils, sleeve and/or mandrel  108  may be axially rotated in the base  102 . Task  234  may be performed subsequent to task  244 . 
     Tasks  234 - 244  may be repeated a predetermined number of times, such that the coils, sleeve and/or mandrel  108  are rotated and compressed the predetermined number of times to provide an even amount of compression on the coils such that the coil body has a round exterior dimension. Each rotation of the coils may include axially rotating the sleeve on the coils. 
     At  245 , the compression block  104  is removed from the base  102  and the coils, sleeve and mandrel  108  are removed from the press  100 . At  246 , the sleeve is removed from the coils and the coils are removed from the mandrel  108 . This may include removing the one or more thermocouples and the second protective layer  193  from the coil body  194 . The coils may be twisted to unstick the coils from the mandrel. 
     At  248 , the resistances measured at  228  may be remeasured and compared with the resistances measured at  228 . If the resistances measured the second time are out of predetermined ranges from the corresponding resistances measure the first time, then one or more of the wires and/or coils may be damaged. The resistances may be measured prior to removal of the coils from the mandrel  108  in order to obtain the resistances between the phase sets and the mandrel  108  (e.g., the resistances R 1   m , R 2   m  and R 3   m ). At  248 , dimensions of the coil body  194  may be measured and compared with predetermined dimensions to assure that the coil body  194  is within predetermined ranges of the predetermined dimensions. This may include measuring lengths, outer diameters, and inner diameters of the coil body  194 . The method may end at  250 . 
     The above-described tasks are meant to be illustrative examples; the tasks may be performed sequentially, synchronously, simultaneously, continuously, during overlapping time periods or in a different order depending upon the application. Also, any of the tasks may not be performed or skipped depending on the implementation and/or sequence of events. 
     The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. 
     In this application, including the definitions below, the term ‘module’ or the term ‘controller’ may be replaced with the term ‘circuit.’ The term ‘module’ may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip. 
     The module may include one or more interface circuits. In some examples, the interface circuits may include wired or wireless interfaces that are connected to a local area network (LAN), the Internet, a wide area network (WAN), or combinations thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules that are connected via interface circuits. For example, multiple modules may allow load balancing. In a further example, a server (also known as remote, or cloud) module may accomplish some functionality on behalf of a client module. 
     The term code, as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, data structures, and/or objects. The term shared processor circuit encompasses a single processor circuit that executes some or all code from multiple modules. The term group processor circuit encompasses a processor circuit that, in combination with additional processor circuits, executes some or all code from one or more modules. References to multiple processor circuits encompass multiple processor circuits on discrete dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the above. The term shared memory circuit encompasses a single memory circuit that stores some or all code from multiple modules. The term group memory circuit encompasses a memory circuit that, in combination with additional memories, stores some or all code from one or more modules. 
     The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc). 
     The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks and flowchart elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer. 
     The computer programs include processor-executable instructions that are stored on at least one non-transitory, tangible computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may encompass a basic input/output system (BIOS) that interacts with hardware of the special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, etc. 
     The computer programs may include: (i) descriptive text to be parsed, such as HTML (hypertext markup language) or XML (extensible markup language), (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. As examples only, source code may be written using syntax from languages including C, C++, C#, Objective C, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5, Ada, ASP (active server pages), PHP, Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, and Python®. 
     None of the elements recited in the claims are intended to be a means-plus-function element within the meaning of 35 U.S.C. § 112(f) unless an element is expressly recited using the phrase “means for,” or in the case of a method claim using the phrases “operation for” or “step for.”