The Spiral Magnetic Motor Slideshow

Spiral Magnetic Gradient
Motor Using Axial Magnets
Credit: Tom
Schum for
spiral stator
construction
Thomas Valone, PhD, PE
Integrity Research Institute
SPESIF, Johns Hopkins Univ., February 24, 2010
http://www.ias-spes.org/SPESIF.html
Gradients 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
Inhomogeneous Magnetic Fields =
Magnetic Gradient
Top View
The net Force
created on the ball
bearing = the
magnetic field
gradient multiplied
by the induced
magnetic moment,
as with the SternGerlach Experiment
--Modern Physics, Schaumm’s Outline Series, Gautreau et al., McGraw Hill, 1978
z
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.
Hartman Patent #4,215,330
drop-off
Fz
Side View
10 degree incline
Steel ball
bearing #4
Two experimental examples that utilize the magnetic field gradient
Spiral Magnetic Motor (SMM)
Uses the Magnetic Gradient
Fθ = M cos φ
dB
dθ
Popular Science, June 1979
FZ = μ cos φ
dB
dz
z
Hartman Patent 4,215,330
U = M r Br + M θ Bθ
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
Creates a constant torque for
75% of each cycle
F = ∇U where U = M · B and
6”
U = M r Br + M θ Bθ
SMM Governing Equations
∂Br
M ∂Br
+M
F=
r ∂θ
∂r
∂Br
T =M
∂θ
W = ∫ T dθ
0
Maximize radial B field (Br) for maximum torque
ENERGY DENSITY CONSIDERATIONS: B-FIELD = 50K x E-FIELD
UB =
1
2
B2
μo
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 !
UE = εo E
1
2
2
Experimental Results
Rotor and Stator B Fields
Six SMM
designs were
tested: 1, 3, 4,
6, 10” rotors
7
6
5
4
kG
3
2
1
0
1.25
3
4
6
R o t o r D iamet er ( in.)
▲ = rotor, ♦ = stator magnetic flux density
10
Spiral Magnetic Motor Angular Velocity
18
16
Polynomial Fit
- - -Data acquisition limit- - -
Angular Velocity (rad/sec)
14
1" rotor
12
3" rotor
10
4" rotor
6" rotor
8
10" rotor
Poly. (4" rotor)
6
4
2
0
90
180
270
0
0.4
0.8
1.6
2.4
3
Angular Displacem ent (radians)
3.8
4.6
degrees
Peak KE, Back Torque, Mass, B-Field
5 Rotors Tested: 1.25”, 3”, 4”, 6”, 10”
1.6
1.4
10” rotor:
0.80 joules
1.2
1
Phototransistor detail
Peak Values:
Kinetic Energy (J)
0.8
Back Torque (N-m)
0.6
Rotor Mass (kg)
0.4
Rotor B Field (T)
Rotor Mass (kg)
0.2
0
1.25
Back Torque (N-m)
3
Kinetic Energy (J)
4
Rotor Diam eter (in.)
6
10
Rotor B Field (T)
Rotor Torque and Potential Energy for One Cycle
10" Rotor Potential Energy (J)
0.9
W = ∫ T dθ
Negative Work Region
0.8
0.7
0.6
0.5
0.4
Positive
Work
Region
0.3
0.2
0.1
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 Torque (N-m)
0
10” rotor tests
315°
1.5
1
0.5
0
-0.5
0
90
180
270
Angular Displacement (degrees)
360
Torque Measurement T=rxF
Prof. Eric Laithwaite’s Suggestion
for 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
B
8
= 1 − 2 e −β t
μH
π
Hysteresis Depends on
Permeability and Resistivity*
B
8 −β t
= 1− 2 e
μH
π
β = πρ /(4μδ )
2
Designing the Growth of Eddy Currents to Match Rotation Speed
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.
ˆ = resistivity,  = permeability, K = thickness of plate, H field is suddenly
applied
*Bozorth, Ferromagnetism, J. Wiley & Sons, 2003
Wiegand causes Barkhausen jumps of magnetic domains that align quickly
Wiegand wires are FeCoV bistable
Vicalloy metal with 2 regions
US 1973 patent # 3,757,754
Used for years for auto ignitions
Provides repeatable magnetic pulse
Pop. Science
MS-PZT
Inverse
magnetostrictive (MS)
effect combined with a
piezoelectric material
(PZT) and voltage
Magnetic Switching for SMM
Piezoelectric Actuator that bends
with very little voltage applied
IRI V-Track Dual SMM
with Radial Magnets
Switching can be applied
to the top stator magnet
Multi-Stage SMM