Linear synchronous motor with multiple time constant circuits, a secondary synchronous stator member and improved method for mounting permanent magnets

• US 20040070286A1
• Filed: 05/23/2003
• Published: 04/15/2004
• Est. Priority Date: 05/24/2002
• Status: Active Grant

• Current Assignee: Velocity Magnetics, Inc.
• Original Assignee: Velocity Magnetics, Inc.
• Inventors: Marzano, Domenic P.
• Granted Patent: US 6,930,413 B2
• Time in Patent Office: Days
• US Class Current: 310/12
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H02K 1/276 Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
• CPC Class Codes: H02K 2201/06 Magnetic cores, or permanent magnets characterised by their skew
• CPC Class Codes: H02K 41/031 of the permanent magnet type

Abstract

The linear synchronous motor consists of a specific primary and secondary part. The secondary portion is a ferromagnetic back plate. An array of permanent magnets are attached to the back plate so that a fixed or variable pole pitch occurs in a precise manner between at least two magnets of alternating polarity which improves existing methods for attaching, guiding, protecting and enhancing the overall flux array produced and emitted by the permanent magnets. A one-piece electrically synchronous linear secondary stator member accompanies a primary member, the synchronous linear permanent magnet motor. The stator electrical frequency is customizeable to allow for a wide variety of braking applications.

Claims

1. A synchronous linear electrical machine operating as a motor or an electrodynamic brake consisting of an array of at least two permanent magnets 1 of alternating polarity;

the magnets 1, being attached to a ferromagnetic back plate 2, that has precision machined countersunk slots 3, to accept the permanent magnets 1, in such a manner that will allow for highly accurate pole pitch, spacing along the magnetic array 1. The countersunk slots 3, surround and keep the highly attractive magnets 1 in place;

a one-piece non-ferromagnetic conductive material, ladder type, frame 4 laminated to an identical one-piece conductive type frame 5 and then welded into a non-magnetic, case 6. The frames 4,5 being blind drilled and tapped to match the bolt pattern 10 of the ferromagnetic back plate 2. Secondary synchronous stator member.

2. The synchronous linear motor of claim 1, wherein the ferromagnetic back plate 2 is the structural or electrical type steel which has precision machined countersunk slots 3, to accept the permanent magnet array 1, at a pre-determined pole pitch spacing, without the use of guide pins or individual raised non-magnetic spacers.

3. The synchronous linear motor of claim 1, wherein the double one-piece non-magnetic, frame 4, which is laminated to an identical one-piece conductive type frame 5 and is then welded into a non-magnetic case 6. The ladder spacers that are parallel to the permanent magnet array 1, provide additional, precise pole pitch alignment and provide secondary protection between each permanent magnet 1.

4. The synchronous linear motor of claim 1, wherein the one-piece conductive ladder type frame 5, which is laminated to the one-piece non-ferromagnetic conductive material, ladder type, frame 4, acts as a spatial harmonic dampening device, which surrounds and shades the upper portion of each permanent magnet 1, thereby reducing spatial harmonics, leakage flux and flux fringing by at least 5%.

5. The synchronous linear motor of claim 3, wherein there is an o'"'"'ring groove 7 precision machined into the mating surface of the one-piece non-ferromagnetic conductive material, ladder type, frame 4 or the mating surface of the ferromagnetic back plate 2. The o'"'"'ring groove 7 is machined near the outside leading edge of this surface area and bolt holes and will accept a one-piece round or a one-piece square o'"'"'ring type rubber seal 7a.

6. The synchronous linear motor of claim 3, wherein the one-piece double non-ferromagnetic conductive material and conductive, ladder type, frames 4,5 are substituted by a cast one-piece conductive alloy frame and cover 11 or machined as such from a solid billet or extruded conductive material. This ladder type frame 11 provides precision parallel pole pitch alignment along the magnetic array 1.

7. The synchronous linear motor of claim 6, wherein the one-piece conductive cast alloy frame 11 will act as a damper circuit, which when attached to the ferromagnetic back plate 2, will surround and shade the outside and upper portion of each permanent magnet 1 within the array 1, thereby reducing spatial harmonics, leakage flux and flux fringing by at least 5%. A further benefit of the frame is to increase the magnetomotive force of each pole during transient mechanical motions, to enhance the air gap magnetic field density and increase dynamic braking thrust.

8. The synchronous linear motor of claim 6, wherein there is an o'"'"'ring groove 7 precision machined into the mating surface of the cast one-piece conductive alloy frame 11 or the mating surface of the ferromagnetic back plate 2. The o'"'"'ring seal groove 7 is machined near the outside leading edge and around the bolt holes of these surfaces and will accept a one-piece round or a one-piece square o'"'"'ring type rubber seal 7a, which will provide a watertight seal when the assembly is bolted together. The seal will eliminate contamination that may otherwise be harmful or damaging to the permanent magnetic material, due to intolerance to aqueous and corrosive environments.

9. The synchronous linear motor of claim 2, wherein the ferromagnetic back plate 2 has a uniquely designed bolt pattern 10 which utilizes countersunk non-magnetic flat head or socket cap bolts 8 to fasten said ferromagnetic back plate 2, to the corresponding frame/cover 4,5,6 or the one-piece cast alloy extruded frame/cover 11. The unique countersunk bolt pattern 11 surrounds each permanent magnet 1 and affixes the one-piece non-ferromagnetic conductive frame and conductive frame/case 4,5,6 or the one-piece cast alloy frame/case 11 in such a manner, that will reduce or eliminate twisting and shifting of the magnet array 1, under high force applications. By reducing or eliminating twist, the outside surface of the non-magnetic case 6 or the outside surface of the one-piece alloy frame/case 11 will maintain a highly accurate and constant air gap between the linear synchronous motor as an assembly 12 and a secondary electrical member.

10. A one-piece synchronous linear secondary stator member, or rail, and a primary double sided synchronous linear permanent magnet electrical machine operating as a motor or electro-dynamic brake consisting of at least two permanent magnets of positive and negative polarity, wherein the double-sided primary synchronous permanent magnet motor maybe affixed stationary to a moving vehicle pathway. As well, the one-piece secondary synchronous linear stator member may be affixed stationary to a moving vehicle or may be affixed in a stationary manner along the vehicle pathway.

11. The system as described in claim 10 wherein the synchronous linear stator member is a one-piece non-layered or multi-layered conductive rail, wherein said rail is slotted at a 90 degree angle at a pre-determined pole pitch spacing, thereby causing a discrete synchronous current path around said slots during transient dynamic motion, wherein laminating more than one conductive material, a variable electro-dynamic brake drag will occur along the synchronous linear secondary stator member as a function of time.

12. The system as described in claim 10 wherein the synchronous linear stator member is a one-piece non-layered or multi-layered conductive rail, wherein said rail is slotted to at least a 1 degree angle at a pre-determined pole pitch spacing, thereby causing a discrete synchronous current path around said slots during transient dynamic motion, wherein laminating more than one conductive material, a variable electro-dynamic brake drag will occur along the synchronous linear secondary stator member as a function of time. Where in by angling the slots at least 1 degree along the secondary synchronous stator member, a reduction of brake pulsation will occur along the synchronous linear secondary stator member, otherwise known as the active braking area.

13. The system as described in claims 10 and 11 wherein the slots contain a non-conductive insulating barrier around the inside edge of said slot and wherein the center of said slot contains a highly permeable steel or ferrite core, thereby said core will boost or sustain the magnetic flux density within the air gap of the double sided primary synchronous linear permanent magnet motor during rapid and decaying transient dynamic motion.

14. The system as described in claim 13 wherein the said slots may not contain the highly permeable steel or ferrite core at particular intervals, thereby reducing initial braking “

jerk rate”

as the moving vehicle, with the affixed double-sided synchronous linear permanent magnet motor, enters the synchronous linear secondary stator member.

15. The system as described in claims 10 and 11 wherein the pole pitch spacing of the slots along the synchronous linear secondary stator member matches the, negative and positive alternating magnet, pole pitch spacing of the synchronous linear double-sided permanent magnet motor, thereby causing a discrete synchronous electrical current and frequency to occur along the said secondary stator member.

16. The system as described in claim 15 wherein by increasing and decreasing the length of said pole pitch spacing of the primary synchronous linear permanent magnet motor magnets and the synchronous linear secondary stator member slots will allow said system to be tuned to a particular electrical frequency upon the initial entry of the vehicle or object into the active braking area. Thereby, as the velocity of the vehicle diminishes or fades, the electrical frequency decreases along the active braking area causing a variable frequency braking effect.