Patent Grant
7687959
The invention generally pertains to electrical motors and more particularly to a brushless a-c motor that utilizes a non-conductive stator having wire windings that are wound parallel to the longitudinal axis of the stator.
Electrical motors are generally classified as alternating-current (a-c) motors or direct-current (d-c) motors. In either classification the motors are designed to receive electrical energy and convert that energy into mechanical energy, also referred to as “torque”. A-c motors are used more often than d-c motors because of the availability of a-c power over d-c power. All motors however, sustain energy losses in converting the electrical energy to the mechanical energy. This loss is due to bearing friction, cogging, the resistance loss that occurs by current flowing through the conductors of the motor armature, the electrical field and core losses that are due to hysteresis and eddy currents. These losses can contribute to a non-smooth rotation, the production of heat and lower efficiency.
Prior art motors utilize laminated metal stators that have wire windings which are wound perpendicular to the longitudinal axis of the rotor. The windings produce the magnetic force that pushes or pulls against a set of magnets which are located around the rotor of the motor. In contrast, the inventive brushless a-c motor utilizes a stator that is made of a non-conductive material such as plastic and a metal rotor that rotates around the stator to produce a rotational force. The non-conductive stator has wire windings that are wound parallel to the longitudinal axis of the stator. The rotational force is produced when current flows through the wires. The combination of the non-conductive stator, the permanent magnets in the rotor and the novel wire winding eliminates or at least minimizes the problems listed above for the prior art motors. Additionally, the inventive design provides a high efficiency electrical energy converter.
A search of the prior art did not disclose any literature or patents that read directly on the claims of the instant invention. However, the following U.S. patents are considered related:
The U.S. Pat. No. 7,183,686 discloses a synchronous motor that includes a stator, a rotor and permanent magnets. The rotor includes a rotor iron core that rotates relative to the stator, and a plurality of conductor bars accommodated within corresponding slots in the rotor iron core. The conductor bars have opposite ends that are short circuited by respective short circuit rings to form a starter cage conductor. The rotor also has a plurality of magnet retaining slots located on an inner side of the conductor bars, in which permanent magnets are embedded.
The U.S. Pat. No. 7,183,684 discloses a permanent magnet rotary motor that can maintain a higher torque density and reduce cogging torque when compared to a conventional permanent magnet rotary motor. A pair of end surfaces from each permanent magnet is used for a rotor that is placed substantially parallel to a virtual plane. The virtual plane extends in the radial direction of a rotor core while passing through the centers of a stator core.
The U.S. Pat. No. 5,894,183 discloses a permanent magnet rotor for an electric generator or motor having a core lamination hub formed from a stack of round plates. The plates have peripheral slots for holding the first end of a rectangular magnet. Each magnet has an outer end which is held by a slotted pole piece formed from laminated plates. A first and a second side plate overlie each side of the lamination hub, the magnets and the pole pieces. Fasteners are passed through holes in the side plates, hub plates and pole pieces to form a rigid rotor.
The U.S. Pat. No. 4,393,320 discloses a permanent magnet rotor comprising a housing defining a central rotor axis and an inner ring secured within the housing. Annularly extending around the rotor axis is a plurality of permanent magnets that are annularly spaced around the inner ring. An outer ring is secured within the housing and annularly extending around the permanent magnets are a plurality of outer ring segments. The rotor has a filler material that fills the spaces between adjacent permanent magnets and adjacent the outer ring segments.
For background purposes and as indicative of the art to which the invention is related, reference may be made to the following remaining patents located in the search:
The brushless a-c motor (BACM) disclosed herein is designed to provide a high performance motor that features a stator which is made of a non-conductive material and has windings that are wound parallel to the longitudinal axis of the stator.
In its basic design, the BACM is comprised of four major elements: a circular stator, a circular rotor, a bearing and a circular belt.
The circular stator is made of plastic and includes an outer surface, a left intermediate surface and a right surface. The outer surface has a multiplicity of longitudinally extending wire notches. Extending from the left intermediate surface is a first set of wire attachment structures and an integral central protrusion.
From the right surface of the stator extends a second set of wire attachment structures. Around and between the two sets of attachment structures and inserted into the longitudinal wiring notches is a multiplicity of insulated wires that are wound parallel to the longitudinal axis of the stator. The ends of the wires exit the stator through a wire exit slot and terminate at an input a-c power source that can be comprised of a singe-phase power source, a two-phase power source or a three-phase power source. The frequency of the input power is proportionally synchronized with the rotational speed of the rotor which is controlled by an electronic control unit.
The circular rotor, which is dimensioned to rotate around the outer surface of the stator, includes an inner surface, an outer surface, a right edge and a left edge. To the inner surface is longitudinally attached a multiplicity of permanent magnets that are equally spaced with alternating north (N) and south (S) poles. To the rotor's right edge is attached a right circular plate and to the rotor's left edge is a left circular plate having a perimeter edge that is spaced from the inner surface of the cylindrical cylinder. The left circular plate also has a centered bore that is dimensioned to be attached over the central protrusion located on the stator.
To further enhance the utility of the BACM the central protrusion further includes a terminus from where extends a rod support cavity that terminates within the confines of the circular stator. Into the cavity is inserted a rigidly attached motor support rod that provides structural integrity and stability to the BACM.
The bearing has a perimeter edge that interfaces with the inner surface of the rotor. The bearing is designed to support the rotor without the need for a motor shaft and to add structural integrity to the BACM which significantly reduces motor vibrations.
The circular belt has a first end that is located around the outer surface of the circular rotor, and a second end that is located around a rotating work piece. Since the belt is located around the rotor, a motor shaft is not required.
In view of the above disclosure, the primary object of the invention is to produce a BACM that utilizes a plastic stator that eliminates the cogging and eddy currents that are prevalent in prior art motors. Additionally, the design of the BACM results in smooth rotation, produces less heat and provides higher torque and speed than similarly sized prior art motors.
In addition to the primary object of the invention it is also an object of the invention to produce a BACM that:
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.
The best mode for carrying out the brushless a-c motor 10 (hereinafter “BACM 10”) is presented in terms of a preferred embodiment and a second embodiment. The preferred embodiment of the BACM 10, as shown in
The preferred embodiment of the BACM 10 is comprised of eight major elements: a stator 12, a motor support rod 38, a rotor 44, a multiplicity of permanent magnets 56, a right circular cooling plate 64, a left circular plate 74, a bearing 80 and a motor support stand 90.
The circular stator 12, as shown assembled in
The stator 12 includes an outer surface 14, a left intermediate surface 16 from where extends integrally a central protrusion 20 having a terminus 22, and a right surface 34. The outer surface 14, as best shown in
Around and between the attachment structures 18 and inserted into the longitudinal wiring notches 36 is a multiplicity of insulated wires 32 that are wound parallel to the longitudinal axis of the stator 12. The ends of the wires 32 are inserted through a wire exit slot 24 that is located on the surface of the central protrusion 20. From the wire exit slot 24, which is dimensioned to accommodate the wiring from the three-phase power source, the wiring extends outward and terminates at the a-c power source 180, as shown in
The central protrusion 20 also includes a rod support cavity 26 that extends from the terminus 22 of the protrusion 20 and that terminates within the circular stator 12, and a keyed slot 28 that extends longitudinally along the surface 30 of the rod support cavity 26.
The motor support rod 38, as also shown in
The circular rotor 44, as shown in
The right circular cooling plate 64 has a diameter with a perimeter edge 66 that is attached flush with the right edge 52 of the cylinder 46 by an attachment means such as a bolt 60. The plate 64 further has a plurality of inward facing fins 72, as shown best in
The left circular plate 74 has a diameter with a perimeter edge 76 that is spaced from the inner surface 48 and flush with the left edge 54 of the cylinder 46. The plate 74 further has a centered bore 78 that is dimensioned to fit over and be attached to the central protrusion 20 located on the stator 12. The perimeter edge 76 has a solenoid cavity 77 into which is inserted an electrically powered, spring-loaded solenoid 42. The solenoid is positioned to engage one of a plurality of locking cavities 58 that are located around the inner surface 48 of the circular cylinder 46, as shown in
The rotor 44, the right circular plate 64, the left circular plate 74 and the motor support rod 38 can be made of a material that is selected from the group consisting of metal or plastic, wherein the plastic is further selected from the group consisting of polyphenylene, polyamide-imide and polyetherimide.
The multiplicity of permanent magnets 56, as shown in
The bearing 80, as shown in
The motor support stand 90 can be produced in several designs. An example of a typical stand 90, as shown in
The BACM 10 does not require an output shaft to transfer the electrical energy to a mechanical energy. Instead, a circular belt 98 can be utilized that has a first end that is wound around the outer surface 50 of the circular rotor 44 and a second end that is wound around a rotating work piece (not shown). To maintain the circular belt 98 in a lateral alignment, the outer surface 50 of the rotor 44 can include a pair of belt securement tabs 88, as shown in
The second embodiment of the BACM 10, which is designed to power at least one wheel of a vehicle, is shown in
The wheel attachment structure 100, as shown in
The circular cylinder 46 has an inner surface 48 and an outer surface 50. From the outer surface 50 and adjacent the left edge 54 of the cylinder 46 extends outward an inner mounting tab 102. The tab 102 has an outer side 104 and an inner side 106, wherefrom the inner side 106 extends inward a threaded mounting stud 108.
The tire rim 112 has an inner surface 114 and an outer surface 116. From the inner side 114 extends downward an outer mounting tab 118 having an outer side 120 and an inner side 122. The inner side 106 of the inner mounting tab 102 interfaces with the outer side 120 of the outer mounting tab 118. The outer mounting tab 118 further has a bore 124 that is dimensioned to accept the threaded mounting stud 108 that secures both the tabs 102,118 when a nut 60 is tightened on the mounting stud 108. The tire rim 112 further has on each rim end 128 a tire mounting structure 130 that interfaces with a tire bead 132 of a tire 134.
While the invention has been described in detail and pictorially shown in the accompanying drawings it is not to be limited to such details, since many changes and modifications may be made to the invention without departing from the spirit and the scope thereof. For example, a motor shaft and gear assembly can easily be attached to the circular rotor 44 to transfer power. Also, the BACM 10 could be modified to function as a generator by driving the rotor 44 and producing a three-phase voltage from the stator 12. Additionally, the BACM 10 is primarily designed to function with a single non-conductive stator 12 and a single rotor 44 that utilizes a plurality of permanent magnets 56. A design having multiple stators 12 and rotors 44 that are concentrically aligned and located around a common single shaft can also be utilized. With this design, a maximum number of magnets 56 and wiring 32, as allowed by the space available, can be utilized to provide a high power output. Hence, this disclosure is described to cover any and all modifications and forms which may come within the language and scope of the claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4097754 | Farr | Jun 1978 | A |
| 4393320 | Anderson | Jul 1983 | A |
| 5767601 | Uchiyama | Jun 1998 | A |
| 5894183 | Borchert | Apr 1999 | A |
| 6093984 | Shiga et al. | Jul 2000 | A |
| 6396177 | Shin et al. | May 2002 | B1 |
| 6429566 | Kuwahara | Aug 2002 | B1 |
| 6727632 | Kusase | Apr 2004 | B2 |
| 6759779 | Neet | Jul 2004 | B2 |
| 6984908 | Rinholm et al. | Jan 2006 | B2 |
| 7183684 | Miyashita | Feb 2007 | B2 |
| 7183686 | Sasaki et al. | Feb 2007 | B2 |
| 7233092 | Murakami et al. | Jun 2007 | B2 |
| 7262526 | Shiga et al. | Aug 2007 | B2 |
