SPECIFICATION
EDDY-CURRENT RETARDING DEVICE
Technical Field
[OOO 1 ]
The present invention relates to an eddy-current retarding device mounted as
an auxiliary brake in transportation means including vehicles such as trucks and
buses, and in particular, to an eddy-current retarding device using permanent
magnets for generating braking force.
The present application claims priority based on Japanese Patent Application
No. 2012- 179 138 filed in Japan on August 13, 2012, the contents of which are
incorporated herein by reference.
Background Art
[0002]
In general, an eddy-current retarding device (hereinafter, also simply
referred to as a "retarding device") employing a permanent magnet (hereinafter, also
simply referred to as a "magnet") includes a brake member fixed to a rotating shaft
such as a propeller shaft, and at the time of braking, causes eddy current to be
generated on the surface of the brake member opposite to the magnet, due to an
effect of a magnetic field from the magnet. With this eddy current generated,
braking force occurs in a direction opposite to the rotational direction of the brake
member rotating integrally with the rotating shaft, thereby reducing the speed of the
rotation shaft.
10003 1
Retarding devices are roughly divided into a drum type and a disk type
according to the shapes of a brake member that causes braking force by generating
eddy current and the shapes of a magnet holding member that holds a magnet and is
paired with the brake member, and there are various structures for switching from
braking to non-braking and vice versa.
[0004]
In recent years, in order to respond to requests for miniaturized devices,
there have been proposed retarding devices that rotatably support, on a rotating
shaft, a magnet holding member that holds the magnet, and brings the magnet
holding member to a stop with a friction brake at the time of braking (see, for
example, Patent Documents 1 to 5). Furthermore, there is proposed a retarding
device in which, by replacing the brake member with the magnet holding member,
the magnet holding member is fixed on the rotating shaft, and the brake member is
rotatably supported on the rotating shaft, thereby stopping this brake member with
the friction brake at the time of braking (see, for example, Patent Document 5).
These retarding devices are called retarding devices with a synchronous rotation
type, because the magnet holding member and the brake member synchronously
rotate at the time of non-braking periods as described below.
[0005]
FIG. 1 is a longitudinal sectional view showing a configuration example of a
conventional retarding device with a synchronous rotation type. The retarding
device shown in FIG. 1 is a disk-type retarding device, and includes a brake disk 101
serving as a brake member, and a magnet holding disk 104 that serves as a magnet
holding member and holds a permanent magnet 105 so as to face the main surface of
the brake disk 10 1.
[0006]
In FIG. 1, the brake disk 101 is configured so as to rotate integrally with a
rotating shaft 11 1 such as a propeller shaft. More specifically, a connecting shaft
112 is fixed with a bolt or other items so as to be coaxial with the rotating shaft 11 1,
and a sleeve 113 with a flange is inserted into the connecting shaft 112 while being
engaged using a spline, and is fixed with a nut 114. The brake disk 101 is fixed, for
example, with a bolt to the flange of the sleeve 113 attached integrally with the
rotating shaft 11 1, which makes it possible to rotate integrally with the rotating shaft
111.
[0007]
The brake disk 101 is provided with radiating fins 102 on, for example, the
outer circuniference of the brake disk 101. These radiating fins 102 are formed
integrally with the brake disk 10 1, and have a f~tnctiono f cooling the brake disk 10 1
itself. The brake disk 101 is formed with an electrically conductive material, which
includes a ferromagnetic material such iron, a soft magnetic material such as ferritic
stainless steel, and a non-magnetic material such as aluminum alloy and copper
alloy.
[0008]
In FIG. 1, the magnet holding disk 104 is configured so as to be able to
rotate with respect to the rotating shaft 11 1. The magnet holding disk 104 may be
integrally formed with a ring-shaped member 103 that is coaxial with the connecting
shaft 112, or may be formed separately and be fixed to the ring-shaped member 103,
for example, with a bolt. The ring-shaped member 103 is supported through
bearings 115a and 115b by the sleeve 113 attached integrally with the rotating shaft
11 1. With this configuration, it is possible for the magnet holding disk 104 to
rotate relatively to the rotating shaft 11 1. The bearings 115a and 115b are filled
with lubricating grease. This lubricating grease is prevented from leaking by
ring-shaped seal members 116a and 116b attached on both ends of the ring-shaped
member 103 in the front and rear direction.
[00091
On a surface of the magnet holding disk 104 opposite to the main surface of
the brake disk 101, plural permanent magnets 105 are fixed in the circumferential
direction. Each of the permanent magnets 105 is oriented in a manner such that a
direction of magnetic poles (north pole or south pole) is in an axial direction of the
magnet holding disk 104, and the permanent magnets 105 are arranged in a manner
such that magnetic poles of magnets adjacent in the circumferential direction are
alternately different from each other.
[OOlO]
In FIG. 1, to the magnet holding disk 104, a magnet cover 120 nsade out of a
thin sheet is attached so as to cover the entire permanent magnets 105. This magnet
cover 120 protects the permanent magnets 105 from iron powder or dust particles,
and at the same time, provides a function of shielding radiant heat coming from the
brake disk 101 to the permanent magnets 105, thereby suppressing a reduction in
magnetic force of each of the permanent magnets 105 due to thermal effects. The
magnet cover 120 is made out of a non-magnetic material so that the magnetic field
does not suffer from any effect from the permanent magnets 105.
[OOl l]
The retarding device shown in FIG. 1 illcludes a disk brake serving as a
friction brake that stops the magnet holding disk 104 at the time of braking. This
disk brake is disposed at the rear of the magnet holding disk 104, and is configured
to include a brake disk 106 formed integrally with the ring-shaped member 103, a
brake caliper 107 having brake pads 108a and 108b located at both sides of this
brake disk 106, and an electrically driven direct-acting actuator 109 that drives this
brake caliper 107. The brake disk 106 is attached to the ring-shaped member 103,
for example, with a bolt, and is attached integrally with the ring-shaped member 103.
[OO 121
The brake caliper 107 has a pair of the brake pads 108a and 108b at the front
and the rear therein. Between the brake pads 108a and 108b, the brake disk 106 is
disposed to face each other with a predetermined gap therebetween, and the brake
caliper 107 is pressed and supported toward the bracket 117, for example, with a bolt
having a spring. This bracket 117 is attached to a non-rotating portion such as a
chassis and a crossmember of a vehicle. Furthermore, the bracket 117 surrounds
the ring-shaped member 103 at a position more rearward than the brake disk 106,
and is supported by the ring-shaped member 103 through a bearing 118 in a rotatable
manner. This bearing 118 is filled with lubricating grease. Leakage of this
lubricating grease is prevented by ring-shaped seal members 119a and 119b attached
on both ends of the bracket 117 in the front and rear direction.
[0013]
The actuator 109 is fixed to the brake caliper 107, for example, with a bolt.
The actuator 109 is actuated with an electrically driven motor 110, and converts
rotary motion by the electrically driven motor 110 to linear motion, thereby linearly
moving the brake pad 108b on the rear side toward the brake disk 106. With this
movement. the brake pad 108b on the rear side presses the brake disk 106. With an
effect of the resulting counterforce, the brake pad 108a on the front side moves
toward the brake disk 106, so that the brake disk 106 is strongly squeezed by the
brake pads 108a and 108b on the front and the rear sides.
LO0141
In the retarding device shown in FIG. 1, the disk brake (friction brake) is not
activated during non-braking periods. At this time, in the case where the brake disk
101 is made out of a ferromagnetic material or a soft magnetic material, as the brake
disk 101 rotates integrally with the rotating shaft 11 1, the magnet holding disk 104
integrated with the ring-shaped member 103 rotates synchronously with the brake
disk 101 due to a magnetic attraction effect between the permanent magnet 105 and
the brake disk 101. With this configuration, there occurs no difference in relative
rotational speed between the brake disk 101 and the permanent magnet 105, and
hence, braking force does not occur.
[00 151
In the case where the brake disk 101 is made out of a non-magnetic material,
the magnetic attraction force does not act between the magnet 105 and the brake disk
101. However, in association with the brake disk 101 rotationally moving in a
magnetic field from the magnet 105, braking force acts on the brake disk 101 due to
the effect of the magnetic field. Thus, the magnet 105 receives the resulting
eounterforce, and rotates in the direction same as the brake disk 101. More
specifically, the magnet 105 rotates at a relative rotational speed slightly differing
from that of the brake disk 101 rotating in the same direction so as to maintain a
balance between the braking force generated as a result of the difference in relative
rotational speed between the brake disk 101 and the magnet 105, and a loss
occurring at a bearing portion due to rotation of the magnet 105 or drag force related
to air resistance caused by rotation of the magnet holding disk 104. In other words,
in the case where the brake disk 101 is made out of a non-magnetic material, the
magnet 105 does not rotate in a fully synchronized manner with the brake disk 101
but substantially synchronously rotates with a slight difference in rotational speed,
whereby non-braking state is maintailled.
100 161
On the other hand, at the time of braking, the disk brake (friction brake) is
caused to activate to make the brake disk 106 squeezed by the brake pads 108a and
108b. With this operation, the magnet holding disk 104 formed integrally with the
ring-shaped rnernber 103 stops rotating. and the rnagnet holding disk 104 is brought
to a stop. If only the magnetic holding disk 104 is brought to a stop when the brake
disk 101 is rotating, a difference in relative rotational speed takes place between the
brake disk 101 and the permanent magnet 105. This causes eddy current to be
generated on the main surface of the brake disk 101 due to an effect of a magnetic
field from the permanent magnet 105, whereby it is possible to cause the braking
force to act on the rotating shaft 11 1 through the brake disk 101. Note that, during
braking periods, the same principle, involving the effect of the magnetic field,
applies regardless of whether the brake disk 101 is made out of a ferromagnetic
material or non-magnetic material, and braking efficiency differs due to a difference
in electrical conductivity or magnetic permeability between materials, which makes
it possible to appropriately select materials for the brake disk 101 at the time of
designing magnetic circuits.
100 171
As described above, the retarding device shown in FIG. 1 has a
configuration in which the brake disk 101 serving as the brake member is connected
to the rotating shaft 11 1, and the magnet holding disk 104 serving as the magnet
holding member is rotatably supported on the rotating shaft 11 1. However, it may
be possible to employ a configuration in which the brake disk 101 and the magnet
holding disk 104 are interchanged with each other. More specifically, it may be
possible to employ a configuration in which the magnet holding disk 104 is fixed to
the rotating shaft 11 1, and the brake disk 101 is rotatably supported on the rotating
shaft 11 1.
[OOlS]
In the case of this retarding device, during non-braking periods, as the
magnet holding disk 104 rotates integrally with the rotating shaft 11 1, the brake disk
10 1 integrated with the ring-shaped member 103 rotates in synchronization with the
magnet holding disk 104 due to the magnetic attraction effect (in the case where the
brake disk 101 is made out of a magnetic material) with the permanent magnet 105
held by the magnet holding disk 104, or the effect of a magnetic field (in the case
where the brake disk 101 is made out of a non-magnetic material). For this reason,
there occurs no difference in relative rotational speed between the brake disk 101
and the permanent magnet 105 of the magnet holding disk 104, and hence, the
braking force does not occur.
[00 191
On the other hand, at the time of braking, the ring-shaped member 103 stops
rotating due to operation of the disk brake, and the brake disk 101 is brought to a
stop. If only the brake disk 101 is brought to a stop when the magnet holding disk
104 is rotating, a difference in relative rotational speed takes place between the
brake disk 101 and the permanent magnet 105 of the magnet holding disk 104. This
causes eddy current to be generated on the main surface of the brake disk 101.
Consequently, braking force in a direction opposite to the rotational direction of the
magnet holding disk 104 rotating takes place in accordance with the Fleming's
left-hand rule based on the interaction between the eddy current generated on the
main surface of the brake disk 101 and magnetic flux density from the permanent
magnet 105, whereby it is possible to reduce the speed of rotation of the rotating
shaft 11 1 through the magnet holding disk 104.
[0020]
Furthermore, in the description of the retarding device with a synchronous
rotation type above, a disk type has been described. However, the same description
applies to the case of a drum type.
Related Art Documents
Patent Document
1002 1)
Patent Document 1: Japanese Unexamined Patent Application, First
Publication No. H4-33 1456
Patent Document 2: Japanese Unexamined Utility Model Application, First
Publication No. H5-80178
Patent Document 3: Japanese Unexamined Patent Application, First
Publication No. 201 1-97696
Patent Document 4: Japanese Unexamined Patent Application, First
Publication No. 201 1- 139574
Patent Document 5: Japanese Unexamined Patent Application, First
Publication No. 201 1-182574
Disclosure of the Invention
Problems to be Solved by the Invention
100221
The conventional retarding device with a synchronous rotation type
described above has the following problems.
First, the friction brake (disk brake) is indispensable in order to stop a
member rotatably supported on the rotating shaft, which is either the brake member
or the magnet holding member, at the time of braking, and in the case where the
brake member and the brake disk are connected in series, the size of the retarding
device increases in the axial direction.
[00231
Second, a strong magnetic flux flows at all times in a space between the
brake member and the magnet of the magnet holding member. Hence, there is a
possibility that ferromagnetic foreign substances such as iron powders enter the
space between the brake member and the magnet holding member and attach therein,
and these foreign substances accumulate and grow. If the foreign substances
accumulate as described above, the brake member or the magnet (magnet cover in
the case where the magnet cover is provided) rubs against the foreign substances in
the case where a difference in relative rotational speed between the brake member
and the magnet takes place at the time of braking, which possibly prevents the
relative rotation between the brake member and the magnet or leads to a
deterioration in performance of the brake member or the magnet.
10024 j
The present invention has been made in view of the problems described
above, and an object of the present invention is to provide an eddy-current retarding
device with a synchronous rotation type having a reduced size by reducing the size
of the device in the axial direction.
Means for Solving the Problem
100251
In order to solve the problems described above and achieve the object
described above, the present invention employs the following aspects.
(I) An eddy-current retarding device according to one aspect of the present
invention includes: a magnet holding member that is coaxially provided to a rotating
shaft and holds plural permanent magnets in a circumferential direction; a brake
member including paired disk portions disposed on both sides of the magnet holding
member in an axial direction of the rotating shaft, a connecting portion that connects
the paired disk portions, and an eddy-current generating portion that causes eddy
current due to rotation of the permanent magnets, this brake member being supported
in a relatively rotatable manner with respect to the rotating shaft; and a friction brake
that causes a friction member to press against the brake member at a time of braking
to bring the brake member to a stop.
[0026]
(2) In the aspect of (1) described above, the brake member may cover an area
around the magnet holding member.
LO0271
(3) In the aspect of (1) or (2) described above, it may be possible to employ a
configuration in which the plural permanent magnets are arranged in a manner such
that different magnetic poles are alternately arranged in a circumferential direction
on a surface of the magnet holding member perpendicular to the rotating shaft. and
are disposed so as to face the eddy-current generating portion formed on an inner
surface of at least one of the paired disk portions.
[0028]
(4) In the aspect of (3) described above, it may be possible to employ a
configuration in which the plural permanent magnets are disposed in plural
through-holes formed in a circumferential direction of the magnet holding member
so as to penetrate the magnet holding member in an axial direction of the rotating
shaft, and each of the poles faces the eddy-current generating portion formed on an
inner surface of each of the paired disk portions.
j00291
(5) In the aspect of (1) or (2) described above, it may be possible to employ a
configuration in which the connecting portion is a cylindrical member that connects
the paired disk portions on an outer periphery, and has an inner peripheral surface
having the eddy-current generating portion formed thereon, and the plural permanent
magnets are arranged in a radial direction of the magnet holding member in a manner
such that different magnetic poles are alternately arranged circumferentially on an
outer periphery side of the magnet holding member, and face the eddy-current
generating portion.
[0030]
(6) In the aspect of (I) or (2) described above, it may be possible to employ a
configuration in which the connecting portion is a cylinder portion that connects the
paired disk portions on an outer periphery, and the eddy-current generating portion
is formed on an inner surface of at least one of the paired disk portions and an inner
peripheral surface of the cylinder portion; the plural permanent magnets are arranged
on an outer periphery of the magnet holding member in a manner such that magnetic
poles are alternately arranged in a circumferential direction; and a ferromagnetic
member is disposed between the plural permanent magnets, and the ferromagnetic
member faces the eddy-current generating portion.
1003 11
(7) In the aspect of any one of ( I ) to (6) described above, an impeller disposed
next to an external surface of each of the paired disk portions and connected to the
rotating shaft may be further provided.
100321
(8) In the aspect of any one of (1) to (7) described above, the friction brake may
include a brake caliper that is fixed to a non-rotating portion of a vehicle provided
with the rotating shaft, and has paired brake pads that serve as the friction member to
squeeze the paired disk portions; and an actuator that actuates the brake caliper, and
moves the paired brake pads toward the disk portions.
10033 1
(9) In the aspect of (8) described above, there may be further provided: a
temperature sensor that is brought into contact with an external surface of each of
the disk portions in association with movement of the brake pads toward the disk
portions, and detects a temperature of the disk portions; and an actuator controlling
unit that stops actuating the actuator in the case where the temperature of the disk
portions detected by the temperature sensor exceeds a predetermined temperature.
100341
(10) In the aspect of (8) or (9) described above, a cooling member that is brought
into contact with an external surface of each of the disk portions in association with
movement of the brake pads toward the disk portions may be further provided.
100351
(1 1) In the aspect of any one of (1) to (10) described above, the brake member
may include a section facing the permanent magnets and having plural wire-wound
coils embedded therein along a circumferential direction.
Effects of the Invention
100361
According to the eddy-current retarding device of each of the aspects of the
present invention, it is possible to reduce the size in the axial direction to achieve
miniaturization.
Furthermore, as described in the aspect of (2), in the case where the magnet
holding member is surrounded with the brake member, it is possible to prevent
foreign substances from entering the space between the brake member and the
permanent magnets, and furthermore, prevent the foreign substances from attaching
to the space between the brake member and the permanent magnets.
Brief Description of the Drawings
100371
FIG. 1 is a longitudinal sectional view showing an example of a
config~~ratioonf a conventional synchrono~~s-rotation-typreet arding device.
FIG. 2A is a schematic view showing the entire configuration of a retarding
device with a synchronous rotation type according to a first embodiment of the
present invention, and is a side view in which part of the device is sectionally shown.
FIG. 2B is a diagram showing a schematic configuration of the retarding
device with a synchronous rotation type according to the same embodiment, and is a
diagram showing a cross section along IIB-IIB in FIG. 2A.
FIG. 2C is a diagram showing a schematic configuration of the retarding
device with a synchronous rotation type according to the same embodiment, and is a
diagram showing a cross section along IIC-IIC in FIG. 2B.
FIG. 3A is a schematic view showing the entire configuration of a
synchronous-rotation-type retarding device according to a second embodiment of the
present invention, and is a side view in which part of the device is sectionally shown.
FIG. 3B is a diagram showing a schematic configuration of the
synchronous-rotation-type retarding device according to the same embodiment, and
is a diagram showing a cross section along IIIB-IIIB in FIG. 3A.
FIG. 3C is a diagram showing a schematic configuration of the
synchronous-rotation-type retarding device according to the same embodiment, and
is a diagram showing a cross section along IIIC-IIIC in FIG. 3B.
FIG. 3D is a diagram showing a schematic configuration of a modification
example of the synchronous-rotation-type retarding device according to the same
embodiment, and is a diagram showing a cross section similar to that in the case of
FIG. 3C.
FIG. 4 is a schematic view showing the entire configuration of a
synchronous-rotation-type retarding device according to a third embodiment of the
present invention.
FIG. 5A is a schematic view showing the entire configuration of a
synchronous-rotation-type retarding device according to a fourth embodiment of the
present invention, and is a side view in which part of the device is sectionally shown.
FIG. 5B is a diagram showing a schematic configuration of the
synchronous-rotation-type retarding device according to the same embodiment, and
is a diagram showing a cross section along VB-VB in FIG. 5A.
FIG. 5C is a diagram showing a schematic configuration of the
synchronous-rotation-type retarding device according to the same embodiment, and
is a diagram showing a cross section along VC-VC in FIG. 5A.
FIG. 6A is a schematic view showing the entire configuration of a
synchronous-rotation-type retarding device according to a fifth embodiment of the
present invention, and is a side view in which part of the device is sectionally shown.
FIG. 6B is a diagram showing a schematic configuration of the
synchronous-rotation-type retarding device according to the same embodiment, and
is a diagram showing a cross section along VIB-VIB in FIG. 6A.
FIG. 7 is a schematic view showing the entire configuration of a
synchronous-rotation-type retarding device according to a sixth embodiment of the
present invention.
FIG. 8 is a schematic view showing the entire configuration of a
synchronous-rotation-type retarding device according to a seventh embodiment of
the present invention.
FIG. 9 is a schematic view showing the entire configuration of a
synchronous-rotation-type retarding device according to an eighth embodiment of
the present invention.
Embodiments of the Invention
LO03 81
The present inventors carried out thorough investigation to achieve the
object described above. As a result, the present inventors found that, in a retarding
device with a synchronous rotation type employing permanent magnets, in order to
reduce the size of the device in the axial direction, it is effective to configure a
friction brake such that: a magnet holding member is connected to a rotating shaft;
this magnet holding member is disposed so as to be located between brake members
in the axial direction of the rotating shaft; these brake members are rotatably
supported on the rotating shaft; and a friction member is pressed against each of the
brake members at the time of braking to bring the brake members to a stop, and then,
the present inventors completed the present invention.
Furthermore, it was found that, in order to prevent foreign substances from
entering a space between each of the brake members and the permanent magnets, it
is effective to employ a friction brake in which: a magnet holding member is fixed to
a rotating shaft; brake members are configured so as to surrot~ndt he entire magnet
holding member; each of the brake members is rotatably supported on the rotating
shaft; and a friction member is pressed against each of the brake members at the time
of braking to bring the brake members to a stop, and then the present invention is
completed.
100391
Hereinbelow, each embodiment of an eddy-current retarding device
according to the present invention will be described in detail.

Below, with reference to FIG. 2A to FIG. 2C, a synchronous-rotation-type
retarding device according to a first embodiment of the present invention will be
described.
FIG. 2A is a schematic view showing the entire configuration of the
synchronous-rotation-type retarding device according to a first embodiment of the
present invention, and a side view in which part of the device is sectionally shown.
Furthermore, FIG. 2B is a diagram showing a cross section along IIB-IIB in FIG.
2A. Furthermore, FIG. 2C is a diagram showing a cross section along IIC-IIC in
FIG. 2B.
[ ~ I o ~ o ]
The synchronous-rotation-type retarding device according to the first
embodiment corresponds to a disk type, and includes a magnet holding member 4
that holds permanent magnets 5, and a brake member I. The brake member I is
configured so as to surround the entire magnet holding member 4 from the outside
thereof.
LO04 1 1
In the first embodiment, the magnet hoiding member 4 has a disk-like shape
whose both ends in the axial direction of a rotating shaft 11 are each provided with a
surface perpendicular to the rotating shaft 11, and is configured such that the magnet
holding member 4 is connected to the rotating shaft 11, and rotates integrally with
the rotating shaft 11. More specifically, a tubular connecting shaft 12 is coaxially
fixed to the rotating shaft 11, for example, with a bolt, and the magnet holding
member 4 is fixed to the connecting shaft 12 through a sleeve 13 press-fitted to this
connecting shaft 12. With this configuration, the magnet holding member 4 rotates
integrally with the rotating shaft 11.
[0042]
As shown in FIG. 2B and FIG. 2C, the magnet holding member 4 has
windows (through holes) penetrated therethrough in the axial direction thereof and
arranged at equal angular intervals in the circumferential direction, and each of the
permanent magnets 5 is fitted into each of the windows in a manner that is fixed
using an adhesive agent or metal fittings. As a result, the permanent magnets 5 are
exposed from surfaces on both sides of the magnet holding member 4 in the axial
direction of the rotating shaft 11, and face inner surfaces of both paired disk portions
la and 1b (which will be described later).
100431
The permanent magnets 5 are arranged in a manner such that each magnetic
pole (north pole, south pole) of the permanent magnets 5 is directed to the axial
direction of the rotating shaft 11, in other words, is directed so as to be parallel to
the axial direction of the magnet holding member 4. Furthermore, the permanent
magnets 5 are arranged in a manner such that magnetic poles of the permanent
magnets 5 alternately intersect the circumferentiaI direction when viewed on a
surface of the rnagnet holding member 4 perpendicular to the rotating shaft 11.
100441
As for a material of the magnet holding member 4, in the case of a
configuration in which each of the permanent magnets 5 is fitted into each of the
windows penetrated through in the axial direction, it is desirable to use a
non-magnetic material such as aluminum and austenitic stainless. at least, around the
windows in the vicinity of each of the permanent magnets 5. Note that it may be
possible to use a non-magnetic material or a ferromagnetic ~naterials uch as carbon
steel for a portion connected with the rotating shaft 1 I .
100451
The brake member 1 includes paired disk portions la and Ib having a
doughnut shape, and a cylinder portion (connecting portion) le that connects these
disk portions la and Ib on the outer periphery thereof, and is configured so as to be
able to rotate with respect to the rotating shaft 11 while surro~rndingth e rnagnet
holding member 4. Furthermore, the brake member 1 has the disk portions la and
lb whose inner surfaces face both surfaces of the magnet holding member 4, and the
cylinder portion lc whose inner peripheral surface faces the outer peripheral surface
of the magnet holding member 4. In the first embodiment, the inner surfaces of the
paired disk portions la and lb form an eddy-current generating portion.
100461
Each of the disk portions la and lb is supported through bearings 15a and
15b with the sleeve 13 that is integrated with the rotating shaft 11. With this
configuration, the brake member I having the paired disk portions la and lb and the
cylinder portion lc can freely rotate in an integrated manner with respect to the
rotating shaft 11. FIG. 2A shows a mode in which the disk portion la on the front
side and the cylinder portion lc are integrally formed, and these are integrated with
the disk portion lb on the rear side using, for example, a bolt.
100471
The brake member 1, in particular, the inner surfaces of the disk portions la
and lb form the eddy-current generating portion. Hence, it is preferable for the
disk portions la and lb to be made out of an electrically conductive material, and in
particular, be made out of a ferromagnetic material such as carbon steel and cast
iron, a soft magnetic material such as ferritic stainless steel, or a non-magnetic
material such as aluminum alloy and copper alloy. Furthermore, in order to further
improve braking efficiency by using the materials described above as a base material
of the brake member, it is more preferable that the surface layer portion of the inner
surface of each of the disk portions la and Ib facing the permanent magnets 5 is
made out of a highly electrically conductive material such as copper and copper
alloy.
[0048]
The brake member 1 has an outer periphery provided with plural radiating
fins 2 formed integrally with the cylinder portion lc. Note that, in the disk portions
la and lb of the brake member 1, these radiating fins 2 may be provided in any area
that does not interfere with formation of a friction member of a friction brake, which
will be described later, for example, in an area of an inner periphery portion of an
external surface. These radiating fins 2 function of cooling the brake member 1
itself.
100491
The retarding device shown in FIG. 2A includes a friction brake that brings
the brake member 1 to a stop at the time of braking. This friction brake includes: a
brake caliper 7 that has brake pads 8a and 8b serving as friction members that
squeeze the outer periphery portion of the brake member 1, in other words, the outer
periphery portion of the external surface of each of the disk portions la and lb from
both sides in the axial direction; and an electrically driven direct-acting actuator 9
that drives this brake caliper 7.
[ooso]
The brake caliper 7 has the brake pads 8a and 8b paired at the front and the
rear. and is pressed and supported toward a bracket 17, for example, with a bolt
provided with a spring, in a state where the brake member 1 is disposed between the
brake pads 8a and 8b with a predetermined gap. This bracket 17 is attached to a
non-rotating portion of the vehicle.
LO05 1 ]
Furthermore, the bracket 17 is rotatably supported, through a bearing 18,
with the sleeve 13 integrated with the rotating shaft 11. However, in the case of a
retarding device mounted on the output side of a transmission of the vehicle, it is not
necessary for the bracket 17 to be supported through the bearing 18 if the bracket 17
is fixed to a transmission cover (non-rotating portion). This is because the
transmission cover is supported through the bearing.
[ 00521
An actuator 9 is fixed to the brake caliper 7, for example, with a bolt. The
actuator 9 is actuated, for example, with an electrically driven motor 10, and
converts rotary motion by the electrically driven motor 10 to linear motion, thereby
linearly moving the brake pad 8b on the rear side toward the disk portion 1b 011 the
rear side. With this movement, the brake pad Sb on the rear side presses the disk
portion lb on the rear side. Furthermore, with an effect of the resulting
counterforce, the brake pad $a on the front side moves toward the disk portion la on
the front side, so that the brake member 1 is strongly squeezed by the brake pads 8a
and 8b on the front and the rear sides.
lo0531
With the retarding device accordi~igto the first embodiment as described
above, the friction brake is not activated during non-braking periods. At this time,
as the magnet holding member 4 rotates integrally with the rotating shaft 11, the
paired disk portions la and lb, which constitute the brake member 1, rotate
synchronously with the magnet holding member 4 due to a magnetic attraction effect
of the permanent magnets 5 held by the magnet holding member 4 (in the case where
the brake member 1 is made out of a magnetic material) or an effect of a magnetic
field (in the case where the brake member 1 is made out of a non-magnetic material).
With this configuration, there occurs no difference in relative rotational speed
between the disk portions la and lb (brake member 1) and the permanent magnets 5
of the magnet holding member 4, and hence, braking force does not occur.
[0054 J
On the other hand, if the friction brake is activated at the time of braking,
the brake member 1 is squeezed by the brake pads 8a and 8b serving as the friction
members. With this operation, the brake member I stops rotating, and the brake
member 1 is brought to a stop. If the brake member 1 is brought to a stop when the
magnet holding member 4 is rotating, a difference in relative rotational speed takes
place between the disk portions la and lb (brake member 1) and the permanent
magnets 5 of the magnet holding member 4. This causes eddy current to be
generated on the inner surface of each of the disk portions la and lb. With the
generation of eddy current on the inner surface of each of the disk portions la and
lb, braking force in a direction opposite to the rotational direction of the magnet
holding member 4 rotating takes place in accordance with the Fleming's left-hand
rule based on the interaction between the eddy current generated on the inner surface
of each of the disk portions la and lb of the brake member 1 and magnetic flux
density from the permanent magnets 5, whereby it is possible to reduce the speed of
rotation of the rotating shaft I1 through the magnet holding member 4.
1 OOSS]
According to the retarding device of the first embodiment, the separately
independent brake disk 106, which is necessary in the conventional retarding device
shown in FIG. 1, is not necessary, and the friction brake that brings the brake
rnernber 1 to a stop by pressing the friction member directly against the brake
member 1 at the time of braking is employed, whereby it is possible to reduce the
size of the device in the axial direction. Moreover, since the entire brake member 1
is surrounded by the magnet holding member 4, the space between the disk portions
la and lb of the brake member 1 and the permanent magnets 5 is isolated from the
outside. Thus, it is possible to prevent foreign substances from entering the space
between the disk portions la and lb of the brake member 1 and the permanent
magnets 5 from the outside, and furthermore, it is possible to prevent the foreign
substances from being attached in this space. This makes it possible to prevent the
deterioration in the performance of the brake member 1 and the permanent magnets 5
due to the attachment of the foreign substances, and furthermore, to secure smooth
relative rotation between the brake member 1 and the permanent magnets 5.
100561
Furthermore, in the first embodiment, the eddy current takes place on the
inner surface of each of the disk portions la and lb of the brake member 1, and the
braking force acts from two surfaces, whereby it is possible to significantly improve
the braking efficiency. Additionally, since the magnet cover 120, which is
necessary in the conventional retarding device shown in FIG. I, is not necessary, it
is possible to further improve the braking efficiency by narrowing the space between
the disk portions I a and lb of the brake member 1 and the permanent magnets 5.
to0571

Below, with reference to FIG. 3A to FIG. 3D, a synchronous-rotation-type
retarding device according to the second embodiment of the present invention will
be described.
FIG. 3A is a schematic view showing the entire configuration of the
synchronous-rotation-type retarding device according to the second embodiment of
the present invention, and is a side view in which part of the device is sectionally
shown. Furthermore. FIG. 3B is a diagram showing a cross section along IIIB-IIIB
in FIG. 3A, and FIG. 3C is a diagram showing a cross section along IIIC-IIIC in
FIG. 3B. Furthermore, FIG. 3D is a diagram showing a schematic configuration of
a modification example of the synchronous-rotation-type retarding device according
to the second embodiment, and is a diagram showing a cross section similar to that
in the case of FIG. 3C.
The second embodiment shown in FIG. 3A to FIG. 3C is based on the
configuration of the retarding device according to the first embodiment, and is
different from the first embodiment in the following points.
[0058]
The magnet holding member 4 has a surface perpendicular to the axial
direction of the rotating shaft 11, and is configured to hold plural permanent magnets
5 at equal intervals in the circumferential direction of the magnet holding member 4.
The permanent magnets 5 are arranged in a manner such that each magnetic pole
(north pole, south pole) of the permanent magnets 5 is directed to the axial direction
of the rotating shaft 11, in other words, to the axial direction of the magnet holding
member 4. The plural permanent magnets 5 are arranged on a surface of the
magnet holding member 4 facing the inner surface of the disk portion la at equal
intervals in the circumferential direction in a manner such that different magnetic
poles are alternately arranged (see FIG. 3B and FIG. 3C).
[0059]
In the second embodiment, the magnet holding member 4 is not provided
with any window as described in the first embodiment, and the permanent magnets 5
are disposed on a surface on one side of the magnet holding member 4. In this
case, it is desirable to efficiently configure a magnetic circuit by using a
ferromagnetic material such as carbon steel, ferritic stainless, and cast iron for a
portion of the magnet holding member 4 to which each of the permanent magnets 5
is fixed. However, for a portion of the magnetic holding member 4 to be connected
with the rotating member 11, a ferromagnetic material may be used or a
non-magnetic material such as aluminum may be used.
[0060]
In the second embodiment, an electrically conductive material is used as a
material of the brake member 1. in particular, of the disk portion la. Others are
similar to those in first embodiment. Hence, the same reference characters are
attached, and explanations thereof will be not be repeated here.
1006 11
With this retarding device according to the second embodiment, operations
and effects similar to those in the first embodiment described above can be obtained.
Furthermore, in the second embodiment, the permanent magnets 5 are
disposed only on the surface of one side of the magnet holding member 4, and
configuration is made such that eddy current is generated on an eddy-current
generating portion formed on the inner side of the disk portion la of the brake
member 1. Thus, although the braking force is smaller than that obtained from the
retarding device according to the first embodiment, the size of the rotating shaft 11
in the axial direction can be reduced.
[0062]
Next, with reference to FIG. 3D, a modification example according to the
second embodiment will be described.
FIG. 3D is a diagram showing a modification example according to the
second embodiment, which has a configuration in which permanent magnets 5 are
arranged on both surfaces of the magnet holding member 4 that does not have any
window formed thereon. In such a case, it is desirable to efficiently configure a
magnetic circuit by using a ferromagnetic material such as carbon steel, ferritic
stainless, and cast iron for a portion of the magnet holding member 4 to which each
of the permanent magnets 5 is fixed. However, for a portion of the magnetic
holding member 4 to be connected with the rotating shaft 11, a ferromagnetic
material may be used or a non-magnetic material such as aluminum may be used.
100631
In the modification example of the second embodiment having the
configuration as described above, independent permanent magnets 5 are each
disposed on both surfaces of the magnet holding member 4, and hence, it is possible
to improve the degree of freedom in arrangement on both sides of the magnet
holding member 4. Furthermore, on both sides of the magnet holding member 4.
each of the permanent magnets 5 causes eddy current to be generated on the paired
disk portions la and Ib, and hence, it is possible to generate a large braking force.
COO641

FIG. 4 is a schematic view showing the entire configuration of a retarding
device with a synchronous rotation type, which is a third embodiment according to
the present invention, and is a side view in which part of the device is schematically
shown. The retarding device according to the third embodiment shown in FIG. 4 is
based on the configuration of the retarding device according to the first embodiment,
and is different from the first embodiment described above in the following points.
[0065]
The retarding device according to the third embodiment corresponds to a
drum type, and has the cylinder portion lc of the brake member 1 formed longer in
the axial direction thereof than that in the first embodiment. The magnet holding
member 4 includes a magnet holding ring 4a formed on the outer periphery thereof
so as to be coaxial with the cylinder portion lc of the brake member 1, and a
plurality of permanent magnets 5 are arranged on the outer peripheral surface of and
in the circumferential direction of the magnet holding ring 4a. The permanent
magnets 5 are arranged in a manner such that each magnetic pole (north pole, south
pole) is directed in the radial direction of the magnet holding member 4.
Furthermore, the permanent magnets 5 face the inner peripheral surface of the
cylinder portion lc of the brake member 1, and different magnetic poles thereof are
alternately arranged circurnferentially on the outer periphery side.
100661
The material of the magnet holding ring 4a is a ferromagnetic material or a
soft magnetic material as is the case with the magnet holding member 4. In the
case of the third embodiment, it is more preferable that, for the cylinder portion lc
of the brake member 1, the surface layer portion of the inner peripheral surface
(eddy-current generating portion) that faces the permanent magnets 5 are made out
of a highly electrically conductive material such as copper and copper alloy.
[00671
With the retarding device according to the third embodiment having the
configuration as described above, during non-braking periods, the rotating shaft 11
rotates integrally with the magnet holding member 4, and the brake rnember 1 rotates
synchronously with the magnet holding member 4 due to the magnetic attraction
effect of the cylinder portion lc and the permanent magnets 5 held by the magnet
holding member 4 (magnet holding ring 4a). Thus, there occurs no difference in
relative rotational speed between the cylinder portion lc (brake member 1) and the
permanent magnets 5 of the magnet holding ring 4a, and hence, braking force does
not occur.
[0068]
On the other hand, if the friction brake is activated at the time of braking to
bring the brake member 1 to a stop, the magnet holding member 4 keeps rotating,
and hence, there occurs a difference in relative rotational speed between the cylinder
portion 1c (brake member 1) and the permanent magnets 5 arranged on the magnetic
holding member 4. This causes eddy current to be generated on the inner
peripheral surface of the cylinder portion lc. Then, braking force in a direction
opposite to the rotational direction of the magnet holding member 4 rotating takes
place due to the interaction between the eddy current generated on the inner
peripheral surface of the cylinder portion 1c of the brake member 1 and magnetic
flux density from the permanent magnets 5, whereby it is possible to reduce the
speed of rotation of the rotating shaft 1 I through the magnet holding member 4.
100691
Therefore, with the retarding device according to the third embodiment, it is
possible to obtain a similar effect to that obtained in the first embodiment.
[0070]
Furthermore, in the third embodiment, eddy current occurs on the inner
peripheral surface of the cylinder portion lc, which is distant from the rotational
center from among the disk portions la and Ib and the cylinder portion Ic, each of
which constitutes the brake member 1. Thus, large braking torque can be obtained,
and it is possible to significantly improve braking efficiency. Furthermore, the
magnet cover 120, which is provided in the conventional retarding device shown in
FIG. 1, is not necessary. Thus, by narrowing the space between the cylinder
portion lc of the brake member 1 and the permanent magnets 5, it is possible to
further improve the braking efficiency.
[007 2 1

FIG. 5A to FIG. 5C are schematic views each showing the entire
configuration of a retarding device with a synchronous rotation type, which is a
fourth ernbodi~nenta ccording to the present invention. FIG. 5A is a side view in
which part of the device is sectionally shown, FIG. 5B shows a cross section along
VB-VB in FIG. 5A, and FIG. 5C is an exploded view showing a cross section along
VC-VC in FIG. 5A. The retarding device according to the fourth embodiment
shown in each of FIG. 5A to FIG. 5C is an example obtained by modifying the
configuration of each of the retarding devices according to the first to the third
embodiments.
(00721
As in the third embodiment, the retarding device according to the fourth
embodiment has the cylinder portion 1c of the brake member 1 formed longer in the
axial direction thereof than that in the first embodiment. The magnet holding
member 4 includes a magnet holding ring 4a having a diameter smaller than that in
the third embodiment and made out of a non-magnetic material, and on the outer
peripheral surface of this magnet holding ring 4a, a plurality of permanent magnets 5
are arrange along the circumferential direction. Furthermore, ferromagnetic
members 4b made out of a magnetic material are disposed between adjacent
permanent magnets 5. These plurality of ferromagnetic members 4b face the inner
surfaces of the paired disk portions la and 1b and the inner peripheral surface of the
cylinder portion lc of the brake member 1. Note that magnetic poles (north pole
and south pole) of the permanent magnets 5 are directed to the thickness direction of
each of the permanent magnets 5, and different magnetic poles are alternately
arranged in the circumferential direction of the magnet holding member 4 (see FIG.
5B and FIG. SC). Furthermore, the ferromagnetic member 4b is made out of a
magnetic material while the magnet holding ring 4a is made out of a non-magnetic
material, and hence, these are magnetically insulated from each other.
10073 1
Furthermore, in the fourth embodiment, as shown in FIG. 5B and FIG. 5C,
the ferromagnetic member 4b is disposed between the permanent magnets 5 adjacent
in the circumferential direction, and this ferromagnetic member 4b is also held by
the magnet holding ring 4a. In FIG. 5C, the flows of magnetic flux between the
permanent magnet 5 and the paired disk portions la and lb are indicated with arrows
with dotted lines.
100741
With the retarding device according to the fourth embodiment having the
configuration as described above, during non-braking periods, the magnet holding
member 4 rotates integrally with the rotating shaft 11, and the disk portions la and
lb and the cylinder portion lc, each of which constitutes the brake member 1, rotates
synchronously with the magnet holding member 4 due to the magnetic attraction
effect of the permanent magnets 5 held by the magnet holding member 4 (magnet
holding ring 4a). Thus, no difference occurs in relative rotational speed between
the brake member 1 and the permanent magnets 5 arranged on the magnet holding
ring 4a, and hence, braking force does not occur.
[0075]
On the other hand, if the friction brake is activated at the time of braking to
bring the brake member 1 to a stop, the magnet holding member 4 keeps rotating,
and hence, there occurs a difference in relative rotational speed between the
permanent magnets 5 arranged on the magnet holding member 4 and the disk
portions la and lb and the cylinder portion l c (brake member I). This causes eddy
current to be generated on the inner surface of each of the disk portions la and lb
and the inner peripheral surface of the cylinder portion lc. Then, braking force in a
direction opposite to the rotational direction of the magnet holding member 4
rotating takes place due to the interaction between the eddy current generated on the
inner surface of each of the disk portions la and lb of the brake member 1 and the
inner peripheral surface of the cylinder portion l c and magnetic flux density from
the permanent magnets 5, whereby it is possible to reduce the speed of rotation of
the rotating shaft I1 through the magnet holding member 4.
100761
Therefore, with the retarding device according to the fourth embodiment, it
is possible to obtain a similar effect to that obtained in the first embodiment.
/ 00771
Furthermore, in the fourth embodiment, eddy current occurs on the inner
surface of each of the disk portions la and lb and the inner peripheral surface of the
cylinder portion 1c of the brake member 1. Thus, the braking force acts from three
surfaces: the inner surfaces of the disk portions la and lb and the inner peripheral
surface of the cylinder portion lc, whereby it is possible to further improve the
braking efficiency. Furthermore, the magnet cover 120, which is provided in the
conventional retarding device shown in FIG. 1, is not necessary. Thus, by
narrowing the space between the permanent magnets 5 and the disk portions la and
lb and the cylinder portion l c of the brake member 1, it is possible to further
improve the braking efficiency.
1007 81

FIG. 6A and FIG. 6B are schematic views each showing the entire
configuration of a retarding device with a synchronous rotation type according to a
fifth embodiment of the present invention. FIG. 6A is a side view in which part of
the device is schematically shown, and FIG. 6B is a diagram showing a cross section
along VIB-VIB in FIG. 6A. The retarding device according to the fifth
embodiment shown in FIG. 6A and FIG. 6B is obtained by modifying the
configuration of the retarding device according to the first embodiment described
above.
[0079j
At the time of actual braking, the brake member 1 is heated due to thermal
energy converted from the kinetic energy of the rotating shaft 11 in association with
eddy current generated on the brake member 1, and thermal energy generated from
slide of the brake member 1 on the friction member of the friction brake. At this
time, within the brake member 1, the magnet holding member 4 holding the
permanent magnets 5 is accommodated. Thus, the heat generated in the brake
member 1 accumulates in the brake member 1, and the brake member 1 has high
temperatures. With the increase in temperatures of the brake member 1,
temperatures of the permanent magnets 5 increase due to radiant heat from the brake
member 1, possibly reducing magnetic force of the permanent magnets 5.
Furthermore, the brake member 1 may suffer permanent deformation resulting from
overheating exceeding the upper allowable limited temperature, and may be affected
by repetitive overheating.
[00801
In order to suppress the thermal-induced demagnetization of the permanent
magnets 5 resulting from overheating of the brake member 1 as described above or
the effect of overheating of the brake member 1, heat generated from the brake
member 1 is configured to be radiated from the radiating fins 2. However, the
brake member 1 is not moving at the time of braking, and hence, the cooling
function of the radiating fins 2 works less effectively than during non-braking
periods when the brake member 1 rotates synchronously with the magnet holding
member 4. Thus, it is desirable to contrive to suppress the increase in temperatures
of the brake member 1.
too8 11
The retarding device according to the fifth embodiment has been obtained by
focusing on the point described above. More specifically, as shown in FIG. 6A and
FIG. 6B, the retarding device according to the fifth embodiment includes impellers
20a and 20b disposed next to the external surface of each of the paired disk portions
1 a and lb constituting the brake member 1. Each of the impellers 20a and 20b is
press fitted and fixed to the connecting shaft 12 integrated with the rotating shaft 11.
[0082]
With the retarding device according to the fifth embodiment having the
configuration as described above, even if the rotational speed of the rotating shaft 11
reduces at the tirne of braking, the impellers 20a and 20b rotate if the rotating shaft
11 rotates. Thus, it is possible to blow air from the impellers 20a and 20b toward
[he brake member 1 that is at rest (see the arrows with a solid line in FIG. 6A).
This makes it possible to forcibly cool the brake member I, and prevent the
temperatures of the brake member 1 from rising.
[0083]
It should be noted that the impellers 20a and 20b as described above are
applicable not only to the retarding device according to the first embodiment but also
to the retarding devices according to the second to the fourth embodiments.
[0084]

FIG. 7 is a schematic view showing the entire configuration of a retarding
device with a synchronous rotation type according to a sixth embodiment of the
present invention. FIG. '7 is a side view in which part of the device is sectionally
shown. The retarding device according to the sixth embodiment shown in FIG. 7 is
obtained by focusing on suppressing the increase in temperatures of the brake
member 1 as in the fifth embodiment, and is obtained by modifying the configuration
of the retarding device according to the first embodiment.
[0085]
More specifically, as shown in FIG. 7, the retarding device according to the
sixth embodiment includes a sheathed temperature sensor 21. This temperature
sensor 21 is fixed to a temperature sensor holder 22 that moves in association with
either one of the brake pads 8a and 8b paired at the front and the rear and serving as
the friction rnember of the friction brake, for example, in association with the brake
pad 8b on the rear side. Here, the temperature sensor 21 is connected with the
temperature sensor holder 22, and at the time of braking, the top end of the sheath of
the temperature sensor 21 is brought into contact with the external surface of the
disk portion lb in association with movement of the brake pad 8b on the rear side
toward the disk portion lb on the rear side. Furthermore, the temperature sensor 21
is connected with an actuator controlling unit 23 that controls actuation of the
actuator 9 of the friction brake.
[0086]
With the retarding device according to the sixth embodiment having the
configuration as described above, during braking periods, the top end of the sheath
of the temperature sensor 21 is brought into contact with the disk portion 1b (brake
member I) on the rear side, and continuously detects temperatures of the disk
portion lb. At this time, the actuator controlling unit 23 monitors temperatures of
the disk portion lb detected by the temperature sensor 21, and stops actuating the
actuator 9 if the temperature exceeds a predeterrnined temperature. Once the
actuation of the actuator 9 is stopped, the brake pads 8a and 8b and the temperature
fensor 21 move away from the disk portion lb, and are switched into a non-braking
state. As a result, the brake member l rotates together with the rotating shaft 1 1,
and the brake member 1 is cooled with the radiating fin 2. Thus, the actuator
controlling unit 23 actuates the actuator 9 again after a predetermined period of time
elapses after actuation of the actuator 9 is stopped, and then, brakes the brake
member 1. With the operations described above, it is possible to suppress the
increase in temperatures of the brake member 1.
[0087]
The predetermined temperature for the actuator 9 to stop activating and the
predetermined period of time for the actuator 9 to restart actuating are set as
appropriate according to materials or shapes or dimensions of the brake member 1,
the magnet holding member 4, and the permanent magnet 5, and are set in advance in
the actuator controlling unit 23. For example, the predetermined temperature is set
in the range of approximately 300 to 400°C, and the predetermined period of time is
set in the range of approximately 5 to 10 seconds.
[00 8 81
It should be noted that the temperature sensor 21 as described above may be
configured to move integrally with the brake pad 8a on the front side. Furthermore,
the temperature sensor 21 is applicable not only to the retarding device according to
the first embodiment but also to the retarding devices according to the second to the
fifth embodiments.
[0089]

FIG. 8 is a schematic view showing the entire configuration of a retarding
device with a synchronous rotation type according to a seventh embodiment of the
present invention. FIG. 8 is a side view in which part of the device is sectionally
shown. As in the fifth embodiment, the retarding device according to the seventh
embodiment shown in FIG. 8 is obtained by focusing on s~~ppressinagn increase in
temperatures of the brake member 1, and by modifying the configuration of the
retarding device according to the first embodiment.
LO090 1
More specifically, as shown in FIG. 8, the retarding device according to the
seventh embodiment includes a water cooling body (cooling member) 24, This
water cooling body 24 is connected with a water-cooling-body holder 25 that moves
integrally with either one of the brake pads 8a and 8b paired on the front and the rear
serving as the friction member of the friction brake, for example, moves integrally
with the brake pad 8b on the rear side. Furthermore, at the time of braking, the
water cooling body 24 is brought into contact with the external surface of the disk
portion lb in association with movement of the brake pad 8b on the bask side toward
the disk portion lb on the rear side of the brake member 1.
YO09 11
Furthermore, a water passage 26 is formed within the water cooling body 24,
and has an inlet port and an outlet port each connected with pipes, not shown.
These pipes are connected with a water cooling system (for example, a radiator) of
the vehicle, and cooling water circulates through the water passage 26 within the
water cooling body 24, whereby low temperatures are maintained at all times.
100921
With the retarding device according to the seventh embodiment having the
configuration as described above, at the time of braking, the water cooling body 24
is brought into contact with the disk portion lb (brake member 1) on the rear side.
Thus, the disk portion lb is forcibly cooled through heat exchange with the water
cooling body 24. As described above, it is possible to prevent the increase in
temperatures of the brake member 1.
[0093]
It should be noted that the water cooling body 24 as described above may be
configured to move integrally with the brake pad 8a on the front side. Furthermore.
the water cooling body 24 is applicable not only to the retarding device according to
the first embodiment but also to the retarding devices according to the second to the
sixth embodiments. Note that, instead of the water cooling body 24, a cooling
member in which cooling oil and the like flows may be used.
j00941

FIG. 9 is a schematic view showing the entire configuration of a retarding
device with a synchronous rotation type according to an eighth embodiment of the
present invention. FIG. 9 is a side view in which part of the device is schematically
ihown. The retarding device according to the eighth ernbodime~lt sllown in FIG. 9
is obtained by modifying the configuration of the retarding device according to the
first embodiment.
[0095]
In order to obtain the braking force, retarding devices employ a basic
principle in which kinetic energy of the rotating shaft 11 is converted into thermal
energy. However, by adding an electric energy recovery function of converting
part of the kinetic energy into electric energy and collecting this energy, it is
possible to improve energy efficiency, and this is expected to expand the device's
applications. This is because, in general, vehicles equipped with the retarding
device have various types of electrical components that require electric power, and
in recent years, hybrid electric vehicles or electric vehicles, in which part or all of
driving power for propulsion is supplied from electrically driven motors, have been
attracting attention.
LO0961
The retarding device according to the eighth embodiment is obtained by
focusing on this point. More specifically, as shown in FIG. 9, the retarding device
according to the eighth embodiment has the following configuration to achieve the
electric energy recovery function. The disk portion 1b on the rear side of the paired
disk portions la and lb constituting the brake member 1 has an inner surface facing
the permanent magnets 5, and in this inner surface. plural wire-wound coils 27 are
embedded in the circumference direction thereof. More specifically, an area of this
inner surface of the disk portion lb facing the permanent magnets 5 is divided into
plural sections in the circumferential direction, and the wire-wound coils 27 are each
mounted along a groove forming the outline of each of the divided sections. Each
of the wire-wound coils 27 is formed by winding, pl~rralti mes, an electrically
conductive wire having high electrical conductivity such as a copper wire.
100971
An electrically conductive wire 28 of each of the wire-wound coils 27 is led
out and is exposed from the external surface side of the disk portion lb on the rear
side, and is connected with a terminal 29 disposed on the external surface of this
disk portion lb. The wire-wound coils 27 and the terminal 29 described above
rotate integrally with the disk portion lb (brake member 1) together with the rotating
shaft 11. The terminal 29 is brought into contact with an electric contact point 30
such as a brush in a slidable manner. This electric contact point 30 is fixed to a
non-rotating portion of the vehicle, and is connected with a battery provided on the
vehicle through a controlling circuit.
[0098]
With the retarding device according to the eighth embodiment having the
configuration as described above, during non-braking periods, the brake member 1
rotates synchronously with the magnet holding member 4 in association with rotation
of the magnet holding member 4 integrally with the rotating shaft 11. In this case,
there occurs no difference in relative rotational speed between the permanent
magnets 5 of the magnet holding member 4 and the disk portions la and lb (brake
member 1). Thus, no change occurs in a magnetic field from the permanent
magnets 5 acting on the inner surface of the disk portion la on the front side and a
magnetic field from the permanent magnets 5 acting on the inner surface of the disk
portion lb on the rear side and the wire-wound coils 27. Therefore, during
non-braking periods, eddy current does not occur on the inner surface (eddy-current
generating portion) of each of the disk portions la and lb, and induced electromotive
force does not occur in the wire-wound coils 27, which means that the braking force
and the electric power do not occur.
LO0991
On the other hand, if the friction brake is activated to bring the brake
member 1 to a stop at the time of braking, the magnet holding member 4 keeps
rotating, and hence, there occurs a difference in relative rotational speed between the
permanent magnets 5 disposed on the magnet holding member 4 and the disk
portions la and lb (brake member I). This causes a change in both the magnetic
field from the permanent magnets 5 acting on the inner surface of the disk portion la
on the front side and the magnetic field from the permanent magnets 5 acting on the
inner surface of the disk portion lb on the rear side and the wire-wound coils 27.
On the disk portion la on the front side, the magnetic field from the permanent
magnets 5 changes, whereby eddy current occurs on the inner surface thereof. On
the other hand, on the disk portion lb on the rear side, the magnetic field from the
permanent magnets 5 changes, whereby eddy c~trrenot ccurs on the inner surface
thereof, and furthermore, the induced electromotive force occurs on the wire-wound
coils 27 through electromagnetic induction. At this time, in association with
rotation of the magnet holding member 4, a state where the magnetic field (magnetic
flux) froin the permanent magnets 5 penetrates the wire-wound coils 27 and a state
where this magnetic field does not penetrate the wire-wound coils 27 alternately
appear, and hence, the eddy current and the induced electromotive force alternately
take place repeatedly.
[O loo]
Then, braking force in a direction opposite to the rotational direction takes
place on the magnet holding member 4 due to the interaction between the eddy
current occurring on the inner surface of each of the disk portions la and lb of the
brake member 1 and magnetic flux density from the permanent magnets 5, whereby
it is possible to reduce the speed of rotation of the rotating shaft 11 through the
magnet holding member 4. Furthermore, the induced electromotive force occurring
on the wire-wound coils 27 is recovered through the electrically conductive wire 28,
the terminal 29, and the electric contact point 30 from the wire-wound coils 27, and
can be collected in a battery as electric power.
[OlOl]
It should be noted that the wire-wound coils 27 as described above may be
configured to be embedded in the disk portion la on the front side, or may be
configured to be embedded in both of the disk portions la and 1b. Furthermore, the
cvire-wound coils 27 are applicable not only to the retarding device according to the
first embodiment but also to the retarding devices according to the second to the
seventh embodiments. In particular, in the case where the wire-wound coils 27 are
applied to the retarding devices according to the third embodiment and the fourth
embodiment, the wire-wound coils 27 may be embedded in the inner peripheral
surface of the cylinder portion lc.
[O 1021
It should be noted that the present invention is not limited to each of the
embodiments described above, and various modifications thereto are possible
without departing from the scope of the present invention.
For example, in each of the embodiments described above, descriptions have
been made of the case where the disk portions la and lb and the cylinder portion 1c
constituting the brake member 1 are made out of an electrically conductive material
to make the brake member 1 serve as an eddy-current generating member.
However, it may be possible to provide the eddy-current generating portion made out
of an electrically conductive material on the inner surface of the disk portions la and
lb or the inner peripheral surface of the cylinder portion lc.
Furthermore, it may be possible to optionally set a combination of locations
where the eddy-current generating portion is formed, from among the inner surfaces
of the disk portions la and lb and the inner peripheral surface of the cylinder portion
1 c.
[O103]
Furthermore, in each of the embodiments described above, descriptions have
been made of the case where the brake member 1 includes the disk portions la and
lb and the cylinder portion lc, and surrounds the magnet holding member 4 from the
outside. However, for example, it may be possible to form a portion that opens to
the outside, on a portion of the connecting portion or the disk portion.
[0 1041
Furthermore, it may be possible to employ a configuration in which thermal
treatment or surface treatment is applied to the outer periphery portion of the
external surface of the disk portion (brake member) against which the friction
member is pressed at the time of braking in order to increase the surface hardness
thereof, or a steel sheet having excellent wear resistance is attached on this outer
periphery portion, thereby reducing the amount of wear. In the case where the
brake member is made out of aluminum alloy, it may be possible to form anodic
oxide coating on the surface thereof in order to improve the wear resistance.
[OlOS]
Furthermore, it is optional as to whether to provide the impellers 20a and
20b connected to the rotating shaft 11, the actuator 9 that moves the paired brake
pads 8a and 8b toward the disk portions la and lb, the actuator controlling unit (not
shown) that stop actuating the actuator 9 in the case where temperatures of the disk
portions la and lb exceed a predetermined temperature, and the cooling member (for
example, the water cooling body 24) that is brought into contact with the external
surface of each of the disk portions la and lb.
[0 1061
Furthermore, as for the friction brake that brings the brake ineinber to a stop
at the time of braking, it may be possible to use not only a friction brake that uses
the electrically driven direct-acting actuator as a driving source and presses the
brake pads against the external surface of the brake member (disk portion) but also a
friction brake that employs an electromagnetic clutch mechanism with
electromagnets and presses a clutch plate serving as the friction member against the
external surface of the brake member, or a configuration that employs a drum brake
mechanism and presses brake shoes serving as the friction member against the outer
peripheral surface of the brake member (cylinder portion).
Industrial Applicability
[0107]
According to the present invention, it is possible to provide the eddy-current
retarding device having the reduced size in the axial direction to be miniaturized,
whereby the present invention has high industrial applicability.
Brief Description of the Reference Symbols
[OlOSl
1 : brake member
la, lb: disk portion (eddy-current generating member)
lc: cylinder portion (eddy-current generating member)
2: radiating fin
4: magnet holding member
4a: magnet holding ring
4b: ferromagnetic member
5: permanent magnet
7: brake caliper
83, 8b: brake pad
9: electrically drive11 direet-acting actuator
10: electrically driven motor
11: rotating shaft
12: connecting shaft
13: sleeve
15a, 15b: bearing
17: bracket
18: bearing
20a, 20b: impeller
21 : temperature sensor
22: temperature sensor holder
23: actuator controlling unit
24: water cooling body (cooling member)
25: water-cooling-body holder
26: water passage
27: wire-wound coil
28: electrically conductive wire
29: terminal
30: electric contact point
106: brake disk
120: magnet cover
We claim:
1. An eddy-current retarding device, comprising:
a magnet holding member that is coaxially provided to a rotating shaft and
holds a plurality of permanent magnets in a circumferential direction;
a brake member including:
paired disk portions disposed on both sides of the magnet holding
member in an axial direction of the rotating shaft;
a connecting portion that connects the paired disk portions; and
an eddy-current generating portion that causes eddy current due to
rotation of the permanent magnets, the brake member being supported in a relatively
rotatable manner with respect to the rotating shaft; and
a friction brake that causes a friction member to press against the brake
member at a time of braking to bring the brake member to a stop.
2. The eddy-current retarding device according to claim 1, wherein
the brake member covers an area around the magnet holding member.
3. The eddy-current retarding device according to claim 1 or 2, wherein
the plurality of permanent magnets are arranged in a manner such that
different magnetic poles are alternately arranged in a circumferential direction on a
surface of the magnet holding member perpendicular to the rotating shaft, and are
disposed so as to face the eddy-current generating portion formed on an inner
surface of at least one of the paired disk portions.
4. The eddy-current retarding device according to claim 3, wherein
the plurality of permanent magnets are disposed in a plurality of
through-holes formed in a circumferential direction of the magnet holding member
so as to penetrate the magnet holding member in the axial direction of the rotating
shaft, and
each of the poles faces the eddy-current generating portion formed on an
inner surface of each of the paired disk portions.
5. The eddy-current retarding device according to claim 1 or 2, wherein
the connecting portion is a cylindrical member that connects the paired disk
portions on an outer periphery, and has an inner peripheral surface having the
eddy-current generating portion formed thereon, and
the plurality of permanent magnets are arranged in a radial direction of the
magnet holding member in a manner such that different magnetic poles are
alternately arranged circumferentially on an outer periphery side of the magnet
holding member, and face the eddy-current generating portion.
6. The eddy-current retarding device according to claim 1 or 2, wherein
the connecting portion is a cylinder portion that connects the paired disk
portions on an outer periphery, and the eddy-current generating portion is formed on
an inner surface of at least one of the paired disk portions and an inner peripheral
surface of the cylinder portion;
the plurality of permanent magnets are arranged on an outer periphery of the
magnet holding member in a manner such that magnetic poles are alternately
arranged in a circumferential direction; and
a ferromagnetic member is disposed between the plurality of permanent
magnets, and the ferromagnetic member faces the eddy-current generating portion.
7. The eddy-current retarding device according to any one of claim 1 to claim
6, further comprising:
an impeller disposed next to an external surface of each of the paired disk
portions and connected to the rotating shaft.
8. The eddy-current retarding device according to any one of claim 1 to claim
7, wherein.
the friction brake includes:
a brake caliper that is fixed to a non-rotating portion of a vehicle
provided with the rotating shaft, and has paired brake pads that serve as the friction
rnernber to squeeze the paired disk portions; and
in actuator that actuates the brake caliper, and moves the paired
brake pads toward the disk portions.
9. The eddy-current retarding device according to claim 8, further comprising:
a temperature sensor that is brought into contact with an external surface of
each of the disk portions in association with movement of the brake pads toward the
disk portions, and detects a temperature of the disk portions; and
an actuator controlling unit that stops actuating the actuator in a case where
the temperature of the disk portions detected by the temperature sensor exceeds a
predetermined temperature.
10. The eddy-current retarding device according to claim 8 or 9, further
comprising:
a cooling member that is brought into contact with an external surface of
each of the disk portions in association with movement of the brake pads toward the
disk portions.
11. The eddy-current retarding device according to any one of claim 1 to claim
. 10, wherein
the brake member includes a section facing the permanent magnets and
having a plurality of wire-wound coils embedded therein along a circumferential
direction.