Slotless electric motor and means of making the same

Abstract

A slotless electric motor and means for making the same, wherein the slotless electric motor has a cylindrical air gap between an inner and outer cylindrical layer. Arcuate orthocyclic windings are secured within the air gap, and electrically connected to an annular circuit board, the annular circuit board further having means to electrically connect power and control wiring to the annular circuit board and therein to the orthocyclic windings.

Description

[0001] SLOTLESS ELECTRIC MOTOR AND MEANS OF MAKING THE SAME

[0002] This invention relates to improvements in electric transducers, such as electric motors, and methods of making the same so that the electric motor of the present invention obtains the advantages of slotless motors but are configured and constructed in a such a manner as to create new and improved motors that are, unlike prior art slotless motors, able to be economically mass produced as well as being scalable.

[0003] BACKGROUND OF THE INVENTION

[0004] Prior art electric motors commonly referred to as slotless motors were constructed according to slotted designs in which the copper conductors of the motor winding were placed between teeth in slots of the laminated iron rotor or stator structure. The slotless designs provide a motor with a relatively small air gap to achieve a desired high permeance, and avoid cogging torque created by earlier motor designs with discontinuous iron teeth that formed the structure supporting conductor - generally copper - windings.

[0005] Slotless motor designs have great potential advantages over conventional slotted designs. The slotless designs have a higher potential level of efficiency due to extremely low eddy current losses, extremely low hysteresis losses, the absence of cogging losses and the lack of appreciable iron losses. High speeds in the range of 40k- 120k rpm are readily attainable. The operation can be perfectly smooth over a wide speed range since there is no cogging due to the absence of teeth in the slotless design. Furthermore, the lack of magneto-strictive noise from the teeth of a normal design allows for very quiet operation. The slotless design is also capable of a faster motor response (acceleration / decel eration) due to a low inductance.

[0006] Various methods have been taught for making slotless motors. For example, U.S. Pat.

[0007] No. 4,954,739, the winding is formed using a cylindrical support with a reduced diameter portion at one end. A fiberglass sleeve is placed around the uniform diameter portion and thereafter preformed coils are placed in position. When the coils are in place, the thicker end turn portions at one end of the winding are flared inwardly at the reduced diameter portion of the support and the other end of the winding is flared outwardly. The winding can then be inserted into the cylindrical back iron shell starting with the inwardly flared end of the winding. The support can thereafter be withdrawn from the outwardly flared end leaving the fiberglass sleeve as part of the motor structure. The winding is encapsulated using a suitable resin after the winding is inserted into the stator shell.

[0008] U.S. Pat. No. 4,130,769 issued Dec. 19, 1978, to Karube describes a layered preformed winding technique for making a slotless, brushless DC motor. A fixture is utilized for preforming flat single layered coils. The preformed coils are placed in the back iron cylinder in a shingle layered fashion with one of the straight coil portions in an outer layer against the back iron and the other straight coil portion in an inner layer. This design appears to be limited to windings with a two conductor thickness.

[0009] U.S. Pat. No. 4,445,061 "Methods of Producing Slotless and Toothless Wound Stator" issued to Robert Lender on Jan. 14, 1986, (now assigned to the assignee of this application) describes a method of making and utilizing a fixture which attaches to a cylindrical stator housing, having a smooth al circumference wall. Once the stator is placed in the fixture, temporary fingers are extended radially inwardly. The coils are then wound around the fingers which form temporary slots similar to those in slotted motor designs. The conductors are thereafter forced outwardly against the inner wall of the back iron cylinder by a non-magnetic, expandable, reformable plastic cylinder. U.S. Pat. No. 4,645,961 "Dynamoelectric Machine Having A Large Magnetic Gap and Flexible Printed Circuit Phase Winding" issued to Herbert Maisky on Feb. 24, 1987, describes the use of a long flexible printed circuit board insulated on both sides. The printed circuit board is rolled in "jelly roll fashion" and placed in the stator back iron cylinder. The winding is closed by soldering in connecting wires at appropriate locations.

[0010] Prior art also teaches other improvements to slotless designs. For example, U.S. Pat. No. 5,998,905 to Richard J. Fougere et al. for Slotless Electric Motor or Transducer and Method for Making Same teaches a novel method of making a slotless electric motor with active winding segments adhesively affixed to a support surface or previously deposited active wire segments to form a self-supporting winding structure.

[0011] A significant drawback to the prior art in the field, however, is that the process of mass manufacturing of slotless designs remained elusive. While the prior art taught designs that are efficient and reduce or eliminate drawbacks to non-slotless designs, to date the speed and cost of manufacturing slotless motors has been prohibitive. Further, none of the prior art teaches slotless motor designs that are easily scalable both in terms of size and in terms of winding configurations to accommodate various needs such as the need for torque over speed and vice versa.

[0012] What is needed therefore is a new slotless motor design that avoids the delays and costs of the production of current slotless motor designs, that allows for ease, low cost, and rapidness of production, is easily modifiable to accommodate varying motor performance requirements, and is also scalable. SUMMARY OF THE INVENTION

[0013] An object of the present invention is to provide for a slotless design for a transducer, such as an electric motor, and methods for making the same, in which in which the active conductor segments of the winding are straight and parallel to each other, and in the preferred embodiment, parallel to the axis of rotation throughout the length of the air gap in the design. In the case of a linear motor the active conductor segments of the winding are preferably parallel to one another and perpendicular to the direction of movement. The present invention teaches a novel slotless electric motor design that improves the speed and efficiency of constructing a slotless electric motor. The present invention further reduces the cost of the construction of a slotless electric motor and provides a scalable slotless electric motor design that may be utilized in a multitude of applications and industries, from small scale toys and appliances to large scale industrial applications.

[0014] The present invention therefore teaches a slotless motor design and method of producing the same that allows for economical mass production and scalability which was unachievable with prior art designs.

[0015] It is therefore an object of the present invention to provide a new slotless motor design and method of making the same.

[0016] It is a further object of the present invention to provide a new slotless motor design that is scalable both in size and in the number of stator windings.

[0017] It is a further object of the present invention to provide a new method of making a slotless motor that is more economically efficient to produce both in terms of material costs and in terms of manufacturing time and effort. It will be understood from the drawings and detailed description of the invention herein that the slotless motor design disclosed that the invention may accommodate any commonly- understood and utilized rotors for electric motors. It will be further understood that the invention as described herein may also be configured as a generator to convert mechanical motion to electrical power.

[0018] GENERAL DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a view of an assembled slotless motor design in accordance with an embodiment of the present invention.

[0020] FIG. 2 is a view of a first cylindrical layer in accordance with an embodiment of the present invention.

[0021] FIG. 3 is a view of a second cylindrical layer in accordance with an embodiment of the present invention.

[0022] FIG. 4 is a view of an orthocyclic winding in accordance with an embodiment of the present invention.

[0023] FIG. 5 is a view of an annular printed circuit board in accordance with an embodiment of the present invention.

[0024] FIG. 6 is a view of a second cylindrical layer disposed within a first cylindrical layer in accordance with an embodiment of the present invention.

[0025] FIG. 7 is a top-down view of orthocyclic windings disposed within an air gap between a second cylindrical layer and a first cylindrical layer in accordance with an embodiment of the present invention.

[0026] FIG. 8 is a view of an annular printed circuit board affixed to a mounting means of a first cylindrical layer in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] A slotless electric motor, as described as follows.

[0028] Referring now to FIG. 1, an assembled slotless electric motor 101 is shown mounted within a motor housing 102, the motor housing further having mounting points 103. It will be understood that the shape of the motor housing and number and configuration of the mounting points 103 may vary depending upon the intended application and mechanical fastening of the motor. The assembled motor 101 is shown with an annular printed circuit board (FIG. 5, 501) affixed to the mounting means (FIG. 2, 206). It will be understood that the annular printed circuit board may be affixed to the mounting means by adhesives well-known in the art. The assembled motor 101 further shows the electrical connections 105 between the annular printed circuit board and the terminal conductor ends (FIG. 4, 403) for electrically energizing the one or more orthocyclic windings (FIG. 4, 401). Also shown is an electrical conductor harness 106 electrically attached to the annular printed circuit board. It will be understood that the electrical conductor harness 106 will vary in design and use depending upon the design and intended use of the motor 101. It will also be understood by those skilled in the art that, although the preferred embodiment as shown includes the annular circuit board, the one or more coils in the assembled motor may be directly attached electrically to one another (in an embodiment comprising two or more coils) and to the electrical conductor harness (FIG. 1, 106).

[0029] Referring now to FIG. 2, a first cylindrical layer 201 comprises a cylindrical inner portion 202 with a first end 203 and a second end 204, and a cylindrical exterior portion 205. The inner portion 202 is preferentially formed of non-conductive non-ferrous material and having an inner surface and an outer surface. The exterior portion 205 is preferentially comprising a material chosen from the group of ferrous materials and having an inner surface and an outer surface. It will be understood by those skilled in the art that the exterior portion, while in this disclosed embodiment is chosen from the group of ferrous materials, advances in the chemical, materials, and electrical arts continues apace, and other materials now known or developed in the future may by chosen as the material for the exterior portion for reasons of efficiency, effectiveness, or appropriateness for a particular application of the invention as disclosed herein.

[0030] The inner portion 202 further comprising mounting means 206 at the first end 203 of the inner portion 202, the mounting means 206 having an outer diameter and an inner diameter wherein the outer diameter is greater than the diameter of the outer surface of the inner portion; the mounting means 206 further comprising two or more raised ridges 207 and disposed between each of the two or more raised ridges 207 a recessed portion 208, the recessed portion further comprising one or more slots 209 configured to have wire connectors disposed within the one or more slots 209. The exterior portion 205 is disposed around the inner portion 202 such that the inner surface of the exterior portion 205 is contacting the outer surface of the interior portion 202 and the diameter of the mounting means 206 of the inner portion having a diameter greater than the diameter of the outer surface of the exterior portion. The exterior portion 205 is preferentially adhesively affixed onto the outer surface of the inner portion 202 using adhesives well known in the art. It will be understood by those skilled in the art that number and circumferential orientation of the one or more slots may be chosen depending upon the number and configuration of the one or more orthocyclic windings desired to be disposed within the one or more slots 209.

[0031] Referring now to FIG. 3, a second cylindrical layer 301 is shown having a central portion 302, the central portion having an inner surface 303, an outer surface 304, a first end 305 and a second end 306, a cylindrical retention lip 307 disposed at the second end 306 of the second cylindrical portion 301, the retention lip 307 having a diameter larger than outer surface of the central portion and further having a raised circumferential edge 308, the raised circumferential edge 308 having an inner surface with a diameter larger than the outer surface of the inner portion (FIG. 2, 202) of the first cylindrical portion 201. The central portion 302 of the second cylindrical portion 301 is disposed (FIG. 6) within the first cylindrical portion 201 such that the second end 204 of the first cylindrical portion 201 is inserted into and contained by the retention lip 307 of the second cylindrical portion 301 and where the central portion 302 of the second cylindrical portion 301 is disposed within the first cylindrical portion 201 there is an air gap (FIG. 6, 602) between the outer surface of the central portion 302 of the second cylindrical portion 301 and the inner surface of the first cylindrical portion 201, the air gap 602 having a vertical axis and a circumferential axis (not shown).

[0032] Referring now to FIG. 4, an orthocyclic winding 401 is shown in accordance with an embodiment of the present invention, the orthocyclic winding 401 having a longitudinal axis 402 and terminal conductor ends 403 for electrically energizing the orthocyclic winding 401 from a chosen electrical power source (not shown). The orthocyclic winding is modified to have an arcuate shape along the longitudinal axis 402 with a convex side 404 and concave side 405. As further shown in FIG. 7, the degree of arcuate shaping applied to the winding 401 is matched to the curvature of the air gap (FIG. 6, 602) between the first cylindrical portion and the second cylindrical portion. It will be understood by those skilled in the art that the invention as described herein may comprise one or more orthocyclic windings, the number of which may be chosen based upon the desired configuration for a particular application, and that the desired configuration may include motors that utilize one or more electrical phases to energize one or more orthocyclic windings. Referring now to FIG. 5, an annular printed circuit board 501 is shown, the annular printed circuit board 501 is configured to be disposed within the mounting means (FIG. 2, 206). The annular printed circuit board 501 further comprises annular connecting holes 502 such that when the circuit board 501 is disposed within the mounting means 206, the terminal conductor ends 403 of the orthocyclic windings 401 mounted within the air gap (FIG. 6, 602) of the motor project through the annular connecting holes 502, and may be electrically connected to the circuit board 501 by means when known in the art, generally through soldering or other means. The annular printed circuit board 501 further comprises connecting means 503 for connecting the annular printed circuit board 501 to the electrical conductor harness (FIG. 1, 106). The circuit board 501 comprises electrical conductors (not shown) the design and printing of are well known in the art, to connect two or more orthocyclic windings to each other and to the electrical and control source for the motor via the electrical conductor harness 106.

[0033] Referring now to FIG. 6, the second cylindrical layer 301 is shown disposed within the first cylindrical layer 201 such that between the second cylindrical layer 301 and the first cylindrical layer 201 there is an arcuate air gap 602.

[0034] Referring now to FIG. 7, an embodiment of the invention is shown with orthocyclic windings 401 disposed within the air gap 602. It will be understood that the embodiment as shown comprises six orthocyclic windings 401, although it will be understood by those skilled in the art that there may be any number of windings sufficient to rotate a rotor disposed within the invention without deviating from the scope of the invention. It will also be understood that number and size of the windings may be changed without deviating from the scope of the invention as the invention as described and claimed herein is designed for and contemplates the invention accommodating multiple configurations of windings depending upon the desired performance of the motor and the particular application for which the disclosed motor is utilized. FIG. 7 further shows the terminal conductor ends 403 of the orthocyclic windings 401 disposed within the slots 209 in the mounting means 206. Preferentially, once the windings 401 are disposed within the invention as shown, the air gap 602 surrounding the orthocyclic windings 401 is sealed with materials commonly known and utilized in the industry, generally dielectric potting adhesives or the equivalent.

[0035] Referring now to FIG. 8, an embodiment of the present invention is shown with the second cylindrical layer 301 disposed within the first cylindrical layer 201, the orthocyclic windings 401 disposed within the air gap between the second and first cylindrical layers (not shown), and the annular printed circuit board 501 positioned within the mounting means 206 of the first cylindrical layer 201. The terminal conductor ends 403 of the orthocyclic windings 401 are disposed within the annular connecting holes 502. In this configuration, the invention may then be completed by affixing the terminal conductor ends 403 to the annular printed circuit board 501 by soldering or other electrical connecting means. Similarly, the electrical conductor harness (not shown) may be electrically connected to the circuit board 501 and the final assembly completed by mounting the invention in a motor housing (FIG. 1,102).

[0036] It will be understood by those skilled in the art that the invention as described herein may be formed and / or molded as multiple portions as described herein, but also may be formed and / or molded as a single piece that provides the one or more slots desired in which the one or more coils will be disposed. In the case of an embodiment that utilizes a method of forming and / or molding as a single piece, it will be understood that the bottom portion of the device may have the same diameter as the top portion of the device. It will also be understood that for some applications it may be desirable to dispose the exterior, ferrous portion of the invention inside of the device such that the one or more windings are outside of the exterior, ferrous portion. This may be done so without deviating from the scope and the intention of the invention as described herein.

[0037] The invention has been described herein in a particular embodiment, and it will be obvious to those skilled in the art in light of the foregoing and the claims that modifications and equivalent structures may be built without deviating from the scope of the invention as described and claimed herein.

Claims

CLAIMSWhat is claimed is:

1. A slotless electric motor, comprisingA first cylindrical layer comprising a cylindrical inner portion with a first end and a second end, and a cylindrical exterior portion;The inner portion being formed of non-conductive non-ferrous material and having an inner surface and an outer surface;The exterior portion comprising a material chosen from the group of ferrous materials and having an inner surface and an outer surface;The inner sleeve portion further comprising mounting means at the first end of the inner sleeve portion, the mounting means having an outer diameter and an inner diameter wherein the outer diameter is greater than the diameter of the outer surface of the inner portion;The mounting means further comprising two or more raised ridges and disposed between each of the two or more raised ridges a recessed portion, the recessed portion further comprising two or more slots configured to have wire connectors disposed within the two or more slots;The exterior portion is disposed around the inner portion such that the inner surface of the exterior portion is contacting the outer surface of the interior portion and the diameter of the mounting means of the inner portion having a diameter greater than the diameter of the outer surface of the exterior portion;The exterior portion being adhesively affixed onto the outer surface of the inner portion;A second cylindrical layer having a central portion with an inner surface, an outer surface, a first end and a second end, a cylindrical retention lip disposed at the second end of the second cylindrical portion, the retention lip having a diameter larger than outer surface of thecentral portion and further having a raised circumferential edge, the raised circumferential edge having an inner surface with a diameter larger than the outer surface of the inner portion of the first cylindrical portion;The second cylindrical portion disposed within the first cylindrical portion such that the second end of the first cylindrical portion is inserted into and contained by the retention lip of the second cylindrical portion and where the second cylindrical portion is disposed within the first cylindrical portion there is an air gap between the outer surface of the central portion of the second cylindrical portion and the inner surface of the of the first cylindrical portion, the air gap having a vertical axis and a circumferential axis;Two or more orthocyclic windings, the two or more orthocyclic windings consisting of an electrical conductor disposed within the air gap between the outer surface of the second cylindrical portion and the inner surface of the first cylindrical portion, the electrically conductive windings further having terminal conductor ends disposed at one end of the longitudinal axis of the windings, the terminal conductor ends disposed within the two or more slots in the mounting means at the first end of the first cylindrical layer, the two or more orthocyclic windings further being retained in place through the use of a dielectric potting compound;An annular printed circuit board disposed within the mounting means, the annular printed circuit board further comprising means for connecting the said terminal conductor ends to the annular printed circuit board.

2. The two or more electrically conductive windings of claim 1, wherein the electrically conductive windings are generally oval and wound in a planar form having a long axis and short axis.

3. The electrically conductive windings of claim 2 wherein the electrically conductive windings are curved such that the two or more windings have a convex surface and a concave surface oriented along the long axis.

4. The electrically conductive windings of claim 3 wherein the windings are disposed along the vertical axis of the air gap within the air gap such that the concave surface of the windings are oriented toward the outer surface of the second cylindrical layer.

5. The electrical assembly of claim 1 wherein the orthocyclic windings are secured within the air gap by means of a dielectric material6. A method of making a slotless electric motor comprising the steps of:Providing for a first cylindrical layer comprising a cylindrical inner portion with a first end and a second end, and a cylindrical exterior portion, where the inner portion is formed of non-conductive non-ferrous material and having an inner surface and an outer surface;The exterior portion is chosen from the group of materials ferrous materials and further having an inner surface and an outer surface;The inner sleeve portion further comprising mounting means at the first end of the inner sleeve portion, the mounting means having an outer diameter and an inner diameter wherein the outer diameter is greater than the diameter of the outer surface of the inner portion;The mounting means further comprising two or more raised ridges and disposed between each of the two or more raised ridges a recessed portion, the recessed portion further comprising two or more slots configured to have wire connectors disposed within the two or more slotsDisposing the exterior portion around the inner portion such that the inner surface of the exterior portion is contacting the outer surface of the interior portion and the diameter of themounting means of the inner portion has a diameter greater than the diameter of the outer surface of the exterior portion;Adhesively affixing the exterior portion onto the outer surface of the inner portion;Providing for a second cylindrical portion having a central portion with an inner surface, an outer surface, a first end and a second end, a cylindrical retention lip disposed at the second end of the second cylindrical portion, the retention lip having a diameter larger than outer surface of the central portion and further having a raised circumferential edge, the raised circumferential edge having an inner surface with a diameter larger than the outer surface of the inner portion of the first cylindrical portion;Disposing the second cylindrical portion within the first cylindrical portion such that the second end of the first cylindrical portion is inserted into and contained by the retention lip of the second cylindrical portion and where the second cylindrical portion is disposed within the first cylindrical portion such that there is an air gap between the outer surface of the central portion of the second cylindrical portion and the inner surface of the of the first cylindrical portion, the air gap having a vertical axis and a circumferential axis;Providing for two or more orthocyclic windings, the two or more orthocyclic windings consisting of a single electrical conductor disposed within the air gap between the outer surface of the second cylindrical portion and the inner surface of the first cylindrical portion, the electrically conductive windings further having terminal conductor ends disposed at one end of the longitudinal axis of the windings, the terminal conductor ends disposed within the two or more slots in the mounting means at the first end of the first cylindrical layer, the two or more orthocyclic windings further being retained in place through the use of a dielectric potting compound;Providing for an annular printed circuit board and disposing the annular printed circuit board within the mounting means and wherein the annular printed circuit board further comprises means for connecting the said terminal conductor ends to the annular printed circuit board; andProviding for means for connecting an electrical supply and control means to the annular printed circuit board.