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Nov. 6, 1962
Filed Oct. 12, 1959
maximilien felix reynst
United grates Patent 0 ice
Patented Nov. 6, 1962
from taking the full ventilator power from the source of
energy if the brake is switched off.
Maximilien Felix Reynst, Eindhoven, Netherlands, as
signor to North American Philips Company, Inc., New
York, N.Y., a corporation of Delaware
Filed Oct. 12, 1959, Ser. No. 845,907
Claims priority, application Netherlands Oct. 11, 1958
2 Claims. (Cl. 310-93)
Preferably, the parts in which the eddy currents are
set up, are arranged to surround the magnet structures,
and the ventilator vanes are disposed between the magnet
structures, while the closing members are provided around
the outer diameter of the cooling ?ns between the parts
in which the eddy currents are set up.
In order that the invention may readily be carried out,
This invention relates to a multipolar magnetic brake 10 an embodiment thereof will now be described, by way of
operating on the eddy current principle, for vehicles, in
example, with reference to the accompanying diagram
particular for motor-cars, at least one part, in which the
matic drawings, in which
eddy currents are set up, being arranged coaxially about
FIGURE 1 is an axial sectional view of a brake in ac
at least one magnet structure, and the parts of the magnet
cordance with the invention, and
structure having relative rotation.
Care must be taken to ensure that the parts in which
the eddy currents are set up, are intensively cooled, since
the energy to be dissipated is completely converted into
heat. The greater the power of the brake, the more heat
FIGURE 2 is a sectional view taken along the line
Permanent magnet structures 2 and 3, which are built
similarly to those described in co-pending patent appli
cation No. 764,147 ?led September 29, 1958, are mounted
must be conducted away.
on a shaft 1. These permanent structures co-operate with
_ It is already known to provide the rotor of a similar
parts 4 and 5, which are arranged in a housing 6 mounted
brake with ventilator vanes in order to obtain a forced
on the shaft 1. The said parts are copper cylinders which
air stream‘ for cooling. These ventilator vanes are
engage iron rings 8 provided with cooling fins‘ 7. The
mounted on the part in which the eddy currents are set
width of the cooling ?ns exceeds the width of the magnet
up, so that they serve also as cooling ?ns. However, the 25 structures 2 and 3. The shaft 1 can be connected to the
requirements to be satis?ed by ventilator vanes and cool
ing ?ns differ from one another, so that for the combina
tion, in general a compromise, must be chosen so that
either the cooling effect or the ventilator effect remains
wheels of the vehicle so as to be rotated. Ventilator vanes
9 are disposed on both sides of each magnet structure 2
and 3. Closing member 10 spaced from the parts 4 and 5
by ?ns 7 ensure that the cooling ?uid is axially directed
below the possible optimum.
30 past the cooling ?ns '7 in a direction shown by the arrows.
It is an object of the present invention to provide a con
A displacement of the permanent magnet structures 2
struction in which the requirements of cooling and of
and 3, or of the parts 4 and 5 (housing 6), along the
ventilation are completely matched.
axis of the shaft 1 not only ensures that the brake is
According to the presently preferred form of the in
switched Oh, but also that the ventilator is shut off to a
vention, the magnet structure is provided with ventilator 35 greater or lesser extent. For this purpose, the‘ventilator
vanes which are arranged axially adjacent ‘the magnet
vanes disposed at the outer sides of the outer magnet
structure, the part in which the eddy currents are set up,
one closing member is disposed, which overlaps this part
and by which the cooling ?uid is directed axially past the
structures, are provided with a protruding rim 11. when
the brake is completely switched off, the permanent mag
net constructions are arranged precisely opposite the open
spaces between parts 4 and 5 in which the eddy currents
are set up, so that they substantially close the path to be
cooling ?ns.
taken by the cooling ?uid.
being provided with cooling ?ns, while axially adjacent
the part in which the eddy currents are set up, at least
Both the cooling ?ns for the part or parts in which the
What is claimed is:
eddy currents are set up and the ventilator vanes can be
1. An eddy current machine comprising a shaft, at least
chosen entirely independently with respect to their num 45 two spaced magnetic means secured on said shaft, a plu
her, position and shape, so that the maximum cooling ef
rality of blower means secured on said shaft sandwiching
?ciency is obtainable. The closing members ensure that
said magnetic means therebetween, radially spaced con
the cooling ?uid is directed in the correct direction past
centric eddy current generator means operatively asso
the cooling ?ns.
ciated with said magnetic means, heat dissipation means
According to a further feature of the invention, a num~ 50 secured to said generator means including a plurality of
ber of magnet structures and co-operating parts are ar
cooling ?ns, whereby ?uid channels are de?ned completely
ranged adjacent axially and axially displaceable relatively
surrounding said eddy current generator means, and a per
forated housing member supporting said generator means
to one another, the spacing between the parts in which
the eddy currents are set up being substantially equal to
and associated dissipation means, said housing member
the width of a magnet structure.
55 supported on said shaft for relative axial movement
The braking power is controlled by the axial displace
ment of the magnet structures relative to the parts in
2. A machine according to claim 1 with the addition of
radially extending ring means secured to the axially ex~
which the eddy currents are set up. Thus, the ventila
treme ends of said blower means.
tor power is adjusted at the same time, since the open
space between the parts in which the eddy currents are set 60
References Cited in the ?le of this patent
up, is closed to a greater or lesser extent by the permanent
magnet structure. When the brake is switched o?, that
is to say, when the permanent magnet structures are dis
Hayes _______________ .. Mar. 8, 1958
posed at the sides of the parts in which the eddy currents
Munson ______________ __ Oct. 13, 1959
are set up, the ventilator is substantially shut oif, since 65 2,908,834
the permanent magnet structures lie opposite the aper
tures between the parts in which the eddy currents are
set up. Thus, the continuously rotating rotor is prevented
France _______________ __ Nov. 5, 1956
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