Post on 06-Feb-2018
Spiral Magnetic Gradient Spiral Magnetic Gradient Motor Using Axial MagnetsMotor Using Axial Magnets
Thomas Valone, PhD, PEIntegrity Research Institute
SPESIF, Johns Hopkins Univ., February 24, 2010
http://www.ias-spes.org/SPESIF.html
Credit: Tom Schum for spiral stator construction
Gradients Are Used for All PowerGradients Are Used for All Power
• Thermal gradient is used for heat pump• Voltage gradient is used for electricity
“pumping” of current• Gravity gradient is used for hydroelectric
power• Pressure gradient used for natural gas and
water pumping• Magnetic gradient is used for nothing so far
The net Force created on the ball bearing = the magnetic field gradient multiplied by the induced magnetic moment, as with the Stern-Gerlach Experiment
Hartman Patent #4,215,330
Side View
10 degree incline
drop-off
--Modern Physics, Schaumm’s Outline Series, Gautreau et al., McGraw Hill, 1978
Their experimental setup: The magnetic field B is more intense near the pointed surface at the top than near the flat surface below, creating a slope in a graph of B vs. z , which is the gradient dB/dz.
Steel ball bearing #4
Top View
FFzz
zz
Inhomogeneous Magnetic Fields = Inhomogeneous Magnetic Fields = Magnetic GradientMagnetic Gradient
Two experimental examples that utilize the magnetic field gradient
Spiral Magnetic Motor (SMM) Spiral Magnetic Motor (SMM) Uses the Magnetic GradientUses the Magnetic Gradient
Popular Science, June 1979
Hartman Patent 4,215,330
θφθ d
dBMF cos=
dzdBFZ φμ cos= z
Spiral Magnetic Motor (SMM)Spiral Magnetic Motor (SMM)Archimedean spiral is used
for SMM stator magnets where r = 6 + θ/2 and B(r) is
linearly dependent on θ
6”
Creates a constant torque for 75% of each cycle
F = ∇U where U = M · B and
r rU M B M Bθ θ= +
r rU M B M Bθ θ= +
SMM Governing EquationsSMM Governing Equations
rBMB
rMF rr
∂∂
+∂∂
=θ θ∂
∂= rBMT
221 EU oE ε=
oB
BUμ
2
21=
For a maximum B field in air of 20 kG(2 Tesla), UB = 2 MJ/m3
For a maximum E field in air of 3 MV/m, UE = 40 J/m3
2,000,000 = 40 X 50,000 !
Maximize radial B field (Br) for maximum torque0
ENERGY DENSITY CONSIDERATIONS:ENERGY DENSITY CONSIDERATIONS: B-FIELD = 50K x E-FIELD
∫= θdTW
Experimental ResultsExperimental ResultsSix SMM designs were tested: 1, 3, 4, 6, 10” rotors
Rotor and Stator B Fields
01234567
1.25 3 4 6 10
R ot o r D iamet er ( in.)
kG
▲ = rotor, ♦ = stator magnetic flux density
Spiral Magnetic Motor Angular Velocity
0
2
4
6
8
10
12
14
16
18
0.4 0.8 1.6 2.4 3 3.8 4.6
Angular Displacement (radians)
Ang
ular
Vel
ocity
(rad
/sec
)
1" rotor
3" rotor
4" rotor
6" rotor
10" rotor
Poly. (4" rotor)
Polynomial Fit
0 90 180 270 degrees
- - -Data acquisition limit- - -
Peak KE, Back Torque, Mass, BPeak KE, Back Torque, Mass, B--FieldField
1.25 3 4 610
Kinetic Energy (J)Back Torque (N-m)
Rotor Mass (kg)Rotor B Field (T)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Rotor Diameter (in.)
Kinetic Energy (J)
Back Torque (N-m)
Rotor Mass (kg)
Rotor B Field (T)
5 Rotors Tested: 1.25”, 3”, 4”, 6”, 10”
10” rotor: 0.80 joules
Phototransistor detail
Peak Values:
-0.5
0
0.5
1
1.5
Angular Displacement (degrees)
10" R
otor
Tor
que
(N-m
)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
10"
Rot
or P
oten
tial E
nerg
y (J
)
0 90 180 270 360
Rotor Torque and Potential Energy for One Cycle
Torque Measurement T=rxF
∫= θdTW
Positive Work Region
Negative Work Region
315°
Positive net work required to move latched rotor at 315° to end (starting point) at 360° :
W = 0.52 Joules
when starting at 0.78 J KE
10” rotor tests
Prof. Eric Prof. Eric LaithwaiteLaithwaite’’ss Suggestion Suggestion for Increased Torquefor Increased Torque
Place metal plate of particular permeability underneath rotor in order to produce:
Favorable Hysteresis Currents
Laithwaite Eric, Propulsion Without Wheels, English Univ. Press, 1970
Hysteresis Depends on Hysteresis Depends on Permeability and Resistivity*Permeability and Resistivity*
teHB β
πμ−−= 2
81
Designing the Growth of Eddy Currents to Match Rotation Speed
teHB β
πμ−−= 2
81 )4/( 2μδπρβ =
*Bozorth, Ferromagnetism, J. Wiley & Sons, 2003
= resistivity, = permeability, = thickness of plate, H field is suddenly applied
Choosing aluminum or copper for example, the permeability will be the same as free space ( o = 4 x 10-7), which is very low and the resistivity is also low. Choosing an aluminum plate that is about a centimeter (1 cm) thick would also be a good choice since the thickness of the sheet "delta" is squared and also in the numerator. Altogether, the calculation shows a relatively slow build-up over a tenth of a second and only about 30% at a millisecond after the stator field magnet is applied to the rotating disk, which is in keeping with a delayed eddy current that would push instead of retard the changing flux as would be normally expected from Lenz’ Law.
Wiegand wires are FeCoV bistableVicalloy metal with 2 regions
US 1973 patent # 3,757,754
Used for years for auto ignitions
Provides repeatable magnetic pulse
Pop. ScienceWiegand causes Barkhausen jumps of magnetic domains that align quickly
Inverse magnetostrictive (MS) effect combined with a piezoelectric material
(PZT) and voltage
MS-PZT
Magnetic Switching for SMM Magnetic Switching for SMM
IRI V-Track Dual SMM with Radial Magnets
Switching can be applied to the top stator magnet
Piezoelectric Actuator that bends with very little voltage applied
MultiMulti--Stage SMMStage SMM