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Claims  |
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What I claim and desire to secure by Letters Patent is:
1. A fishing reel comprising a frame, a line spool rotatably mounted in the
frame, a magnetic brake including a plurality of permanent magnets, magnet
supporting means to support said magnets, means to movably mount said
magnet supporting means for movement in said frame, and a rotary surface
including magnetically activable material and connected to be rotated by
said line spool when said line spool is rotated, said magnets having pole
ends facing said surface in such spaced relationship thereto that the
magnetic field therebetween is capable of inducing eddy current therein
when said line spool with said surface is rotated, thereby to effect a
braking torque on the rotating line spool via said surface, the force of
said braking torque being related to the strength of said magnetic field
and to the distance between said pole ends and said surface, said
supporting means being movable by said means to movably mount said
magnetic supporting means for movement in relation to said surface between
first and second end positions, said pole ends in said first and second
end positions of said supporting means being positioned, respectively, at
a predetermined minimum and a predetermined maximum distance from said
surface, and said magnetic brake further comprising guide means for
guiding said magnet supporting means between said end positions in
combination with rotational movements, and spring biasing means connected
to said magnet supporting means and tending to rotate and thereby to move
said magnetic supporting means in one direction to one of said first and
second positions, the counter-electromotive force induced in said surface
when the latter, together with the line spool, is rotated tending to
rotate and thereby to move said magnet supporting means in the opposite
direction against the action of said biasing means, whereby the actual
position of said magnet supporting means between said first and second end
positions and, hence, the braking effect of said magnetic brake on said
line spool are automatically adjusted in dependence upon the speed of
rotation of the line spool, said magnet supporting means supporting said
magnets in positions in which the axes of said magnets are parallel to the
rotational axis of said line spool, and wherein said rotary surface is a
substantially radial surface.
2. A fishing reel comprising a frame, a line spool rotatably mounted in the
frame, a magnetic brake including a plurality of permanent magnets, magnet
suporting means to support said magnets, means to movably mount said
magnet supporting means for movement in said frame, and a rotary surface
including magnetically activable material and connected to be rotated by
said line spool when said line spool is rotated, said magnets having pole
ends facing said surface in such spaced relationship thereto that the
magnetic field therebetween is capable of inducing eddy current therein
when said line spool with said surface is rotated, thereby to effect a
braking torque on the rotating line spool via said surface, the force of
said braking torque being related to the strength of said magnetic field
and to the distance between said pole ends and said surface, said
supporting means being movable by said means to movably mount said
magnetic supporting means for movement in relation to said surface between
first and second end positions, said pole ends in said first and second
end positions of said supporting means being positioned, respectively, at
a predetermined minimum and a predetermined maximum distance from said
surface, and said magnetic brake further comprising guide means for
guiding said magnet supporting means between said end positions in
combination with rotational movements, and spring biasing means connected
to said magnet supporting means and tending to rotate and thereby to move
said magnetic supporting means in one direction to one of said first and
second positions, the counter-electromotive force induced in said surface
when the latter, together with the line spool, is rotated tending to
rotate and thereby to move said magnet supporting means in the opposite
direction against the action of said biasing means, whereby the actual
position of said magnet supporting means between said first and second end
positions and, hence, the braking effect of said magnetic brake on said
line spool are automatically adjusted in dependence upon the speed of
rotation of the line spool, said rotary surface being a substantially
cylindrical surface supported by said line spool and coaxial therewith,
said magnet supporting means being in the form of a unitary support
supporting said magnets in positions with their axes extending
substantially radially and with said pole ends at least partially
surrounded by said cylindrical surface, and means to rotatably and
eccentrically mount said support for rotary movement of said support in
opposite directions by means of the force of reaction from said rotary
surface of said support and the biasing force acting thereon from said
biasing means to effect radial movement of said magnets in the direction
of and away from, respectively, said rotary surface.
3. A fishing reel comprising a frame, a line spool rotatably mounted in the
frame, a magnetic brake including a plurality of permanent magnets, magnet
supporting means to support said magnets, means to movably mount said
magnet supporting means for movement in said frame, and a rotary surface
including magnetically activable material and connected to be rotated by
said line spool when said line spool is rotated, said magnets having pole
ends facing said surface in such spaced relationship thereto that the
magnetic field therebetween is capable of inducing eddy current therein
when said line spool with said surface is rotated, thereby to effect a
braking torque on the rotating line spool via said surface, the force of
said braking torque being related to the strength of said magnetic field
and to the distance between said pole ends and said surface, said
supporting means being movable by said means to movably mount said
magnetic supporting means for movement in relation to said surface between
first and second end positions, said pole ends in said first and second
end positions of said supporting means being positioned, respectively, at
a predetermined minimum and a predetermined maximum distance from said
surface, and said magnetic brake further comprising guide means for
guiding said magnet supporting means between said end positions in
combination with rotational movement, and spring biasing means connected
to said magnet supporting means and tending to rotate and thereby to move
said magnetic supporting means in one direction to one of said first and
second positions, the counter-electromotive force induced in said surface
when the latter, together with the line spool, is rotated tending to
rotate and thereby to move said magnet supporting means in the opposite
direction against the action of said biasing means, whereby the actual
position of said magnet supporting means between said first and second end
positions and, hence, the braking effect of said magnetic brake on said
line spool are automatically adjusted in dependence upon the speed of
rotation of the line spool, said magnetic brake comprising an adjusting
means for adjusting the bias of said spring biasing means, said adjusting
means comprising operating means mounted to be accessible from the outer
side of the fishing reel. |
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Claims |
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Description |
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The present invention relates to a magnetic brake for inductive braking of
the line spool of a fishing reel.
Magnetic brakes of this type are used for braking the line spool during
casting so as to prevent the line spool from rotating at a higher speed
than the reeling-out speed of the line, which generally results in
backlash and overrunning of the spool with consequent tangling of the
line.
Examples of the state of the art are disclosed in the SE patent
specification No. 8203630-2 and GB patent application No. 2,092,872.
In prior art magnetic brakes of this type, the effect of the magnetic brake
can be manually adjusted by means of an adjusting device, but for each
selected setting of the magnetic brake, this acts in such a manner that
the braking force is largest at the beginning of a cast when the speed of
rotation of the line spool is highest and thereafter decreases rapidly
with the decrease of the speed of rotation. At the final stage of the cast
or even before, the braking force has decreased to a low value and, at the
moment the bait attached to the fishing line reaches the surface of the
water and the line pull-out force produced by the bait at the end of the
line ceases, it has reached an almost negligible value. Thus, also during
the final stage of the cast, it may happen that the line spool rotates at
a speed higher than the reeling-out speed of the line.
The object of the invention is to provide a magnetic brake whose braking
effect is automatically adjusted by the speed of rotation of the line
spool.
According to the invention, this object has now been achieved in a fishing
reel comprising a frame, a line spool rotatably mounted in the frame, a
magnetic brake including a plurality of permanent magnets, magnet
supporting means movably mounted in said frame and supporting said
magnets, and a rotary surface consisting of magnetically activable
material and connected to be rotated by said line spool when the latter is
rotated, said magnets having pole ends facing said surface in such spaced
relationship thereto that the magnetic field therebetween is capable of
inducing eddy current therein when said line spool with said surface is
rotated, thereby to effect a braking torque on the rotating line spool via
said surface, the force of said braking torque being related to the
strength of said magnetic field and to the distance between said pole ends
and said surface, said supporting means being movable in relation to said
surface between first and second end positions, said pole ends in said
first and second end positions of said supporting means being positioned,
respectively, at a predetermined minimum and a predetermined maximum
distance from said surface, and said magnetic brake further comprising
guide means for allowing said magnet supporting means to be moved between
said end positions in combination with rotational movements only, and
spring biasing means connected to said magnet supporting means and tending
to rotate and thereby to move said magnetic supporting means in one
direction to one of said first and second positions, the
counter-electromotive force induced in said surface when the latter,
together with the line spool, is rotated tending to rotate and thereby to
move said magnet supporting means in the opposite direction against the
action of said biasing means, whereby the actual position of said magnet
supporting means between said first and second end positions and, hence,
the braking effect of said magnetic brake on said line spool are
automatically adjusted in dependence upon the speed of rotation of the
line spool.
The invention will be described in more detail hereinbelow in some
embodiments with reference to the accompanying drawings, in which:
FIG. 1, with a view to illustrating the principle of the invention for
automatically adjusting the braking effect, in a schematic perspective
view illustrates a magnetic brake according to the invention which
cooperates with a schematically and only partly illustrated line spool;
FIG. 2 is an equally schematic and fragmentary perspective view of a
modified embodiment;
FIG. 3 is a perspective view of two mutually separated parts of a magnetic
brake in a practical embodiment according to the invention; and
FIG. 4 is a perspective view of a fishing reel equipped with a magnetic
brake according to the invention.
In FIG. 1, there is shown a line spool 1 which is rotatably mounted on or
together with a shaft 2. These parts are the only components of a known
fishing reel of the so-called multiplying type that are illustrated in
this Figure, but it may be mentioned that the line spool 1, if rotatably
mounted on the shaft 2, is adapted to be driven by the handle of the
fishing reel via a transmission and a clutch which is disengageable for
disengaging the line spool such that it can rotate freely. If the line
spool is instead fixedly connected in rotational respect to the shaft 2,
the shaft is rotatably mounted and adapted similarly to be driven by the
transmission and the handle and be disengaged therefrom.
The line spool has an end wall 3 which in a per se known manner, although
modified according to the invention, cooperates with a magnetic brake
generally designated 4 which is mounted with a certain mobility, as will
be described in more detail hereinbelow, in the fishing reel axially on
one side of the line spool and coaxially in relation to the line spool 1
and the shaft 2. In the illustrated embodiment, the shaft 2 extends
through an opening 5 in a frame 6 associated with the magnetic brake and
carrying a number of magnets. In the embodiment of FIG. 1, the frame 6 of
the magnetic brake forms a cylindrical magnet support holding a circular
row of small, preferably cylindrical magnets placed in pockets in the
magnet support. The circular row of magnets is coaxial with the line spool
shaft 2 to which the longitudinal axes of the magnets are parallel. Of the
pole ends 7 facing the end wall 3 of the line spool, every other is a
north pole and every other a south pole. During rotation of the line
spool, a counter-electromotive field due to eddy currents generated in the
circular wall 3 tends to act as a braking torque against rotation of the
line spool in a per se known manner. The distance between the pole ends 7
of the magnets and the wall 3 of the line spool is variable by axial
displacement of the magnet support 6, whereby the braking power can be
adjusted.
It is customary that such adjustment is carried out manually by means of a
control knob accessible from the external side of the fishing reel, for
instance as disclosed in the above-mentioned SE patent specification No.
8203630-2.
According to the invention, however, the adjustment of the axial setting of
the magnet support is automatically effected in dependence upon the speed
of rotation of the line spool.
The magnet support is mounted for rotational movement back and forth
through a certain angle about the axis of rotation of the line spool and,
as earlier mentioned, is also axially displaceable within certain limits.
The magnets bring about a braking effect by producing the field of eddy
currents in the wall 3 of the line spool. Naturally, this braking effect
exerts a torque on the magnet support and if the magnet support had been
rotatable without any friction, the magnet support would participate in
the rotation of the line spool with a certain drag depending upon inertia.
According to the invention, this fact is used for producing, by the torque
on the magnet support during rotation of the spool, axial displacement of
the magnet support in a direction towards or away from the line spool. To
counterbalance the torque produced by the field on the magnet support and
to axially return the magnet support in a direction towards or away from
the line spool, the magnet support is connected to a spring load of a
suitable type. In the embodiment shown in FIG. 1, the spring load simply
consists of a helical spring 8 hooked to one end of a lever 9 of the
magnet support 6. The spring is adapted to be stretched by a tractive
force exerted at the other end by an adjusting device 10.
Further, the magnet support 6, in its outer circumferential surface, has a
number of cam grooves 11, preferably three, which are curved, for instance
helical with a suitable pitch, e.g. about 15.degree., in relation to the
axis of the spool or magnet support. A guide pin 12, stationary with
respect to the frame (not shown) of the fishing reel, engages in each such
cam groove 11.
This arrangement forces the magnet support to execute an axial movement
when it is rotated on account of the indicated torque upon rotation of the
line spool. By this action, the magnet support is displaced at a high
speed of rotation of the line spool in one direction to an axial end
position against the action of the spring load and when the speed of
rotation of the line spool successively decreases, the magnet support is
successively rotated by the spring load in the opposite direction and in
accordance with the decrease of the braking torque. The magnitude of the
freedom of movement of the magnet support for rotation and axial
displacement can be limited by selecting the length and pitch of the cam
grooves 11, but preferably and as shown in FIG. 1, the rotational movement
is restricted and, hence, the axial movement in the direction of the line
spool by a stop 14 connected to the frame of the fishing reel, and an
abutment 15 in the form of a projection on the magnet support, such that
this will be prevented, upon axial movement, from contacting any rotary
part, especially the end wall 3 of the line spool.
Since the stop 14 and the abutment 15, which may be relatively sturdy,
arrest the magnet support in an inner end position, the guide pins 12 will
be protected against deforming or surface-damaging abutment forces against
the cam groove ends which, in principle, may be used as abutments
cooperating with the pins 12.
When, at the beginning of a cast, the line spool 1 is rotated at a high
speed, said field exerts a maximum torque on the magnet support, if the
influence of the axial distance between the pole ends of the magnets and
the wall 3 is disregarded, which cannot however be done. Assuming that the
magnet support at the beginning of a cast is at a maximum distance from
the wall 3 of the line spool, the magnet support is displaced in a
direction towards the line spool by being rotated by the indicated torque,
and the closer the line spool comes to the wall 3, the more powerful
becomes the power of the torque since the magnetic field increases with
the reduction of said distance. Under these circumstances, the magnet
support will be rapidly displaced in a direction towards the line spool to
its inner end position by the very rapid rotation at the beginning of a
cast. The braking effect on the line spool is greatest at the initial
phase of the cast when the speed of rotation of the line spool is highest,
and as the speed of rotation decreases, the spring load causes the magnet
support to be moved in a direction away from the line spool, whereby the
braking torque is reduced.
Such a mode of operation bears a certain resemblance to the mode of
operation in a manually adjustable magnetic brake. Also in such a brake,
the braking torque is very powerful at the beginning of a cast and
successively decreases with a decreasing speed of rotation. The difference
is that in the latter case, i.e. in a manually adjustable magnetic brake,
the axial distance between the magnet poles and the line spool is constant
during the cast and the braking torque will not decrease as rapidly as in
the former case.
Thus, in both these cases the braking power decreases in a certain
proportion to the speed of rotation of the line spool and attains low
values at the final stage of the cast.
It is however desirable to maintain the braking effect of the magnetic
brake on the line spool during a longer phase of the cast, preferably
until the bait fixed to the line reaches the surface of the water, so as
to allow the angler to effect a cast without having to brake the line
spool with his fingers during the final stage of the cast.
According to the invention, this is achieved in that the magnet support 6
is urged towards a rear position which is at a greater distance from the
line spool than at the beginning of a cast, in order thereafter to
successively approach the line spool as the speed of rotation decreases.
In this manner, it is achieved that the braking effect on the line spool
at the beginning of a cast decreases very rapidly in that the magnet
support is quickly moved in a direction away from the line spool,
whereupon the distance up to the line spool successively decreases and the
braking power is maintained on the desired level.
This can be achieved by selecting the direction of the pitch of the cam
grooves 11 such that the torque acting on the magnet support by the
rotation of the line spool forces the magnet support to move in a
direction away from the line spool against the action of the spring bias
which, as soon as it overcomes the torque produced by said field, will
rotate the magnet support in the opposite direction so as to return the
magnet support in a direction towards the line spool.
By suitably designing the cam curve for converting the rotational movement
into an axial movement, it is possible to obtain a braking torque which
compensates for the decrease of the speed of the line spool during
casting.
From FIG. 2, to which reference is now made, it appears however that axial
movement of the magnet support is not necessary for achieving the object
of the invention.
The embodiment illustrated in FIG. 2 differs from that of FIG. 1
substantially in that the movement of rotation of the magnet support 6',
as produced by said field, automatically adjusts the braking effect by
bringing about a radial change of the distance of the magnets 7 in
relation to an axial rotary surface which in FIG. 2 is represented by an
axial flange 3' of one end wall 3 of the line spool 1.
To this end, the magnet support in FIG. 2 is mounted on a circular
circumferential surface 20 of an eccentric 21 which is supported on the
shaft 2, here fixed, of the line spool but which, as alternatively, may be
supported on any other fixed part of the fishing reel, such that the
circular circumferential surface 20 of the eccentric is eccentric in
relation to the axis of rotation of the line spool. The magnet support 6'
is retained in its resting position by the spring 8 and in an angular
position by means of a pair of abutment members 14, 15 of the same type as
in FIG. 1. The torque on the magnet support inductively generated on
rotation of the line spool tends to rotate the magnet support against the
action of the tension spring 8. The end position of such a movement of
rotation is determined by an abutment 22 which is fixed or adjustable from
outside. When the speed of rotation of the spool is high, as at the
beginning of a cast, the magnet support is rapidly rotated in a direction
towards the end position defined by the abutment member 22, the magnets 7,
in this case disposed on a sector-shaped radially outer part 23 of the
magnet support, being moved in a direction radially inwardly from the
flange 3', as at the same time the sector 23 is moved a certain distance
in the circumferential direction. As a result the average distance of the
set of magnets from the flange 3' is decreased and the pretensioned spring
8 is further tensioned. When the speed of rotation of the line spool
decreases, the spring is capable of returning the magnet support, the
magnets being moved radially closer to the flange 3'. As in the embodiment
in FIG. 1, this means an automatic adjustment of the effect of the
magnetic brake on the line spool without the need of any axial
displacement of the magnet support. As in the embodiment in FIG. 1, the
spring bias can be adjusted by means of a suitable adjusting device which
is accessible from the outer side of the fishing reel and which is shown
at 10 as a lever or an eccentric 10' acting on the straight end portion 8'
of the spring 8.
The principle of movement of the magnet support as shown in FIG. 1 is also
applicable to the radial setting of the distance between the magnets of
the of the magnet support and a rotary axial surface. If the magnets are
placed with vertical axes on a cylindrical circumferential part of the
magnet support in FIG. 1, inwardly of a conical flange, as opposed to the
axial flange in FIG. 2, the average distance between the pole ends and the
conical flange is actually changed upon axial displacement of the magnet
support. The same applies if the magnets are placed on a conical part of
the magnet support for cooperation with an axial flange of the type shown
in FIG. 2. These and other variants of the embodiments in FIGS. 1 and 2
are conceivable. For instance, use may be made of an internally threaded
hub supported by the magnet support and cooperating with an external
thread of a fixed part for producing axial displacement of the magnet
support upon rotation thereof.
FIG. 3 shows the main components of a practical embodiment according to the
principle of a magnetic brake 4 according to the inventions illustrated in
FIG. 1. As in FIG. 1, the magnet support and the magnets are designated 6
and 7, respectively. The device for transforming a rotary movement into an
axial movement of the magnet support 6 with the magnets 7 here comprises a
guide ring 25 which is intended to be connected to the frame of the
fishing reel, between the frame and a cover serving as external end wall.
Since no parts of the fishing reel itself are shown in FIG. 3, said frame
and cover are not visible. The mode of operation agrees with that
described with reference to FIG. 1, i.e. the magnet support 6 is displaced
axially in a direction towards and away from one end wall of the line
spool by being rotated back and forth within a fraction of a revolution,
for instance 10.degree.-15.degree. depending on the pitch of the guide
curve.
The magnet support 6, which is annular, is dimensioned and designed for
mounting in the central opening of the guide ring 25 with the pole ends 7
facing one end wall of the line spool and spaced a small distance
therefrom. The magnet support 6 and the guide ring 25 are so arranged in
relation to each other that the magnet support when mounted in place in
the guide ring 25 is rotatable and at the same time axially displaceable
relative to the guide ring connected to the frame of the fishing reel,
within predetermined limits for the angular and axial movements. Apart
from this mobility, the guide ring 25 constitutes an external holder which
supports and retains the magnet support 6 in place.
According to a preferred embodiment, the magnet support 6 has, along its
relatively narrow outer circumferential surface, a number of guide or cam
grooves 11', preferably three, which are designed with a certain pitch
angle in the outer circumferential surface of the magnet support in the
area between the opposite end surfaces thereof. The pitch may range for
instance from about 15.degree. to 20.degree. and need not necessarily be
equally large or small throughout the entire length of the guide groove
but may vary according to a curve in dependence upon the special
characteristic it is desirable to give the axial movement and, hence, the
adjustment of the braking torque in dependence upon the speed of rotation
of the line spool and the rotational movement of the magnet support 6
depending thereupon. Inclined, thread fragment-like guide tongues 12'
which are supported by the guide ring and extend radially inwardly from
the inner circumferential surface of said ring engage in the guide grooves
and force the magnet support to move axially when being rotated. The ends
of the cam grooves 11' may be arranged, in cooperation with the tongues,
to form stops but, alternatively or preferably, the magnet support has an
axial projection which is arranged to cooperate with one or two spaced
apart abutments (not shown) which are connected to the ring or to said
outer cover and, hence, are connected to the frame of the fishing reel.
Both or either of these abutments may be adjustable from the outer side of
the fishing reel for maximizing and/or minimizing the movement or stroke
of the magnet support. Also in other respects, the device operates
according to the principle described with reference to FIG. 1 and, thus,
also comprises an adjustable spring 8' exerting a torque on the magnet
support for returning it in a direction towards an axial starting position
from which the magnet support is displaced in the above-described manner
by the quick rotational movement of the line spool at the beginning of a
cast.
In the illustrated embodiment, the spring 8' is a slender helical spring
acting between a lever 9 on the magnet support and a circularly curved
adjusting slide 28 adapted to adjust the spring bias and movable along a
circumferential guide surface 26 followed by a guide groove 27 of the
guide ring 25. Also, it may be mentioned that the guide surface 26 and the
guide groove 27 merely have about half width for the spring-adjusting
slide 28 and that the above-mentioned cover (not shown) has a
corresponding guide groove and guide surface which are partly
complementary to the guide groove 27 and guide surface 26 of the magnet
ring to the entire width of the slide when the guide ring is mounted in
the above-described manner between the cover and the frame of the fishing
reel, but through a short distance along the region of the surface 26 the
guide ring and the cover leave a small gap through which the spring
attachment 29 on the slide extends in between said parts (ring and cover).
The spring-adjusting slide has a handle 30 which is accessible from
outside for changing the bias of the spring, which may be a tension spring
8, by moving the slide back and forth in the circumferential direction of
the guide ring within the length of the guide surface 26. In the position
of use, the spring extends along a substantially circular arc about the
outer circumference of the magnet support 6. Each intentionally adjusted
angular position of the slide is maintained unaltered, for instance by
means of a spring lock, such as a spring wire (not shown) connected to the
cover and acting against a fluted edge surface 31 of the slide.
It should however be observed that the arrangements for the spring bias and
for the conversion of rotational movement of the magnet support into axial
movement where applicable or quite generally for moving the pole ends of
the magnets closer to and away from a rotary surface adjacent said pole
ends, may vary according to the design, as selected in each particular
case, of the other constructional details of the magnetic brake according
to the invention. The opposite forces acting on the magnet support by
means of the spring 8 and as a result of the induced reactive force which
acts as braking torque on the line spool are allowed to balance each other
by the mobility of the magnet support which tends to maintain the balance
by changing positions. In one case of theoretical interest, which might be
used for special purposes, the positional change of the magnet support may
be such that the braking effect attains a maximum at the beginning of a
cast and thereafter decreases rapidly. However, in the preferred instance,
the magnet support moves in a direction to maintain the braking torque on
the line spool despite a decreasing speed of rotation during casting, and
by suitably designing the means for guiding the movement of the magnet
support and the spring bias, the movement of the magnet support may
additionally be given a character to further adjust the braking torque.
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