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03/2000 |
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Discussion on
the principles of Hybrid reluctance magnet
 A
closed magnetic tract that combines a permanent magnet and an
electromagnet, the core of this invention, shall be referred
to as the basic factor.
The basic factor is composed of
a permanent magnet (a) and an electromagnet (b). The permanent
magnet is obtained by sandwiching a neodymium magnet (hard magnetic)
with pure iron bars (soft magnetic) in the ---- direction. The
electromagnet is obtained by winding a copper wire coil around
a core ( -shaped soft magnetic (pure iron)).
 Regarding
the basic factor, interfaces between the permanent magnet and
the electromagnet "p" and "q" are important.
[1] When no electricity passes
through the electromagnet (b) (off)
The line of magnetic force from
the permanent magnet (a) merely circulates the closed magnetic
tract of the basic factor, and almost leakage of magnetic flux
occurs into air. Therefore, the interfaces "p" and
"q" strongly attract each other. In this case, attraction
of "p" and "q" is due to the permanent magnet
alone.
[2] When electricity which generates
magnetic fluxes in a larger number than magnetic fluxes from
the permanent magnet (a) is passed through the electromagnet
(b) with the two poles in opposite positions
The line of magnetic force of
permanent magnet (a) is released into the air if it is pushed
back by the line of magnetic force of electromagnet (b) above
the "p" and "q" contact surface and exceeds
the saturation of permanent magnet (a). In this case, if the
number of magnetic fluxes is large enough, the line of magnetic
force released in the air is the synthesis of permanent magnet
(a) and electromagnet (b). Therefore, the "p" and "q"
contact surface shows strong adsorption, which is solely due
to electromagnet (b).
[3] When electric current which
generates magnetic fluxes in the same number as permanent magnet
(a) in electromagnet (b) is passed and the residual magnetic
flux density of the basic factor is not yet saturated, the "p"
and "q" contact surface does not either attract or
repel each other (powerless status).
This means that in this status,
the line of magnetic force of permanent magnet (a) and that of
electromagnet (b) do not communicate each other via the "p"
and "q" surface. The number of magnetic fluxes of permanent
magnetic (a) and that of electromagnetic (b) that exceed the
saturation of residual magnetic flux density of the basic factor
are equal and large, contact surfaces "p" and "q"
repel each other and the line of magnetic force of each surface
leaks into the air as magnetic flux.
[4] In status mentioned in [3]
above, the action surface of the basic factor is defined as (x),
and a mobile material composed of a soft magnetic material (pure
iron) adjacent to (x) as (y). In the status mentioned in [3]
above, electric current input into electromagnetic b is defined
as a (value at a point where the "p" and "q"
contact surface is powerless).
 In
the status mentioned in [4] above, the a value decreases gradually
as the air gap between the basic factor and mobile material (y)
is reduced. This means that the line of magnetic force of permanent
magnet a forms a magnetic tract via the air gap vs mobile material
(y) and generates attractive power on action surface (x) without
forming a closed magnetic tract within the basic factor beyond
the "p" and "q" contact surface. In this
case, the amount necessary to block the line of magnetic force
of permanent magnet (a) on the "p" and "q"
contact surface can be large enough for being an a value input
into electric magnet (b). Consequently, the easier it is for
the line of magnetic force of permanent magnet to form a magnetic
tract with mobile material (y), i.e., the greater the attractive
power on action surface (x), the smaller the a value. Naturally,
the attractive power on action surface (x) is determined by the
performance of the permanent magnet. However, if a large amount
of electric current is inputted into the electromagnet (b) as
in [2] above, the attractive power on action surface (x) is the
synthesis of the lines of magnetic force from permanent magnet
(a) and electromagnet (b). This results in a great attractive
power but energy utilization efficiency decreases.
In order to increase the attractive
power on action surface (x) and decrease the value in the status
mentioned in [4] above, thee conditions can be considered:
1. To reduce the air gap on action
surface (x)
2. For the core of permanent magnet
(a) and the soft magnetic of movable part (y), to use a material
whose saturation magnetic flux density is greater than that for
the material used for the core of electromagnet (b).
3.To make the distance of the
magnetic tract that forms movable part (y) via permanent magnet
(a) and the air gap (L2) shoter than that of the closed magnetic
tract in basic factor (L1). Needless to say, it is important
to improve the performance of the permanent magnet (Br, BH) in
order to increase the attractive power on action surface (x).
New materials that may replace neodymium (e.g., super-conducting
magnet) are under development.
An appropriate distance (width)
of the permanent magnet in the flux direction (L) and an appropriate
length of permanent magnet (a) (XL) can be calculated from the
cross section area (Z), Br, BH curve, and permeance coefficient.
This makes it possible to determine the optimal size of permanent
magnet (a) and mobile material (b). An electromagnet b) compatible
with permanent magnet (a) should be designed taking statuses
[1] through [4] into account.
[Conclusion]
A. Combination of electromagnet
(b) and mobile material (y).
B. Combination of the basic factor
and mobile material (y).
For comparison, the air gap, material,
distance of the magnetic tract, area of the cut surface, volume,
coil thickness, and other conditions for "A" and "B"
above must be the same as much as possible. If the attractive
power on the action surface in "A" and "B"
above is the same, the electric power input in the case of "B"
above is several times smaller than in the case of "A"
above. In the case of a reluctance motor in the form of "A"
above, the energy conversion rate is usually about 30%. If a
reluctance motor produced in the form of "B" above
requires 30% or less of electric power input compared to a motor
produced in the form of 1 above, electric output greater than
input can be theoretically expected. This proves that energy
of a permanent magnet is converted into dynamic power.
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