Eddy-current retarding device

Abstract

This eddy-current retarding device 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 that includes paired disk portions disposed on both sides of the magnet holding member in the 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, and 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 the time of braking to bring the brake member to a stop.

Claims

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 to each other; 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 presses against the paired disk portions of 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, 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, 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, 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 claim 1, 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 claim 1, 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 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.

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, 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 claim 1, 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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a longitudinal sectional view showing an example of a configuration of a conventional synchronous-rotation-type retarding device.

(2) 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.

(3) 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.

(4) 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.

(5) 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.

(6) 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.

(7) 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.

(8) 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.

(9) 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.

(10) 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.

(11) 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.

(12) 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.

(13) 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.

(14) 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.

(15) 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.

(16) 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.

(17) 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

(18) 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.

(19) 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 surround the 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.

(20) Hereinbelow, each embodiment of an eddy-current retarding device according to the present invention will be described in detail.

First Embodiment

(21) 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.

(22) 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.

(23) 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 1. The brake member 1 is configured so as to surround the entire magnet holding member 4 from the outside thereof.

(24) In the first embodiment, the magnet holding 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.

(25) 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 1a and 1b (which will be described later).

(26) 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 circumferential direction when viewed on a surface of the magnet holding member 4 perpendicular to the rotating shaft 11.

(27) 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 material such as carbon steel for a portion connected with the rotating shaft 11.

(28) The brake member 1 includes paired disk portions 1a and 1b having a doughnut shape, and a cylinder portion (connecting portion) 1c that connects these disk portions 1a and 1b on the outer periphery thereof, and is configured so as to be able to rotate with respect to the rotating shaft 11 while surrounding the magnet holding member 4. Furthermore, the brake member 1 has the disk portions 1a and 1b whose inner surfaces face both surfaces of the magnet holding member 4, and the cylinder portion 1c 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 1a and 1b form an eddy-current generating portion.

(29) Each of the disk portions 1a and 1b 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 1 having the paired disk portions 1a and 1b and the cylinder portion 1c can freely rotate in an integrated manner with respect to the rotating shaft 11. FIG. 2A shows a mode in which the disk portion 1a on the front side and the cylinder portion 1c are integrally formed, and these are integrated with the disk portion 1b on the rear side using, for example, a bolt.

(30) The brake member 1, in particular, the inner surfaces of the disk portions 1a and 1b form the eddy-current generating portion. Hence, it is preferable for the disk portions 1a and 1b 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 1a and 1b facing the permanent magnets 5 is made out of a highly electrically conductive material such as copper and copper alloy.

(31) The brake member 1 has an outer periphery provided with plural radiating fins 2 formed integrally with the cylinder portion 1c. Note that, in the disk portions 1a and 1b 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.

(32) 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 1a and 1b from both sides in the axial direction; and an electrically driven direct-acting actuator 9 that drives this brake caliper 7.

(33) 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.

(34) 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.

(35) 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 on the rear side. With this movement, the brake pad 8b on the rear side presses the disk portion 1b on the rear side. Furthermore, with an effect of the resulting counterforce, the brake pad 8a on the front side moves toward the disk portion 1a 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.

(36) With the retarding device according to 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 1a and 1b, 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 1a and 1b (brake member 1) and the permanent magnets 5 of the magnet holding member 4, and hence, braking force does not occur.

(37) 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 1 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 1a and 1b (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 1a and 1b. With the generation of eddy current on the inner surface of each of the disk portions 1a and 1b, 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 1a and 1b 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.

(38) 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 member 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 1a and 1b 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 1a and 1b 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.

(39) Furthermore, in the first embodiment, the eddy current takes place on the inner surface of each of the disk portions 1a and 1b 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. 1, is not necessary, it is possible to further improve the braking efficiency by narrowing the space between the disk portions 1a and 1b of the brake member 1 and the permanent magnets 5.

Second Embodiment

(40) 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.

(41) 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.

(42) 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.

(43) 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 1a at equal intervals in the circumferential direction in a manner such that different magnetic poles are alternately arranged (see FIG. 3B and FIG. 3C).

(44) 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.

(45) In the second embodiment, an electrically conductive material is used as a material of the brake member 1, in particular, of the disk portion 1a. Others are similar to those in first embodiment. Hence, the same reference characters are attached, and explanations thereof will be not be repeated here.

(46) With this retarding device according to the second embodiment, operations and effects similar to those in the first embodiment described above can be obtained.

(47) 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 1a 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.

(48) Next, with reference to FIG. 3D, a modification example according to the second embodiment will be described.

(49) 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.

(50) 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 1a and 1b, and hence, it is possible to generate a large braking force.

Third Embodiment

(51) 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.

(52) The retarding device according to the third embodiment corresponds to a drum type, and 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 formed on the outer periphery thereof so as to be coaxial with the cylinder portion 1c 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 1c of the brake member 1, and different magnetic poles thereof are alternately arranged circumferentially on the outer periphery side.

(53) 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 1c 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.

(54) 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 member 1 rotates synchronously with the magnet holding member 4 due to the magnetic attraction effect of the cylinder portion 1c 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 1c (brake member 1) and the permanent magnets 5 of the magnet holding ring 4a, and hence, braking force does not occur.

(55) 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 1c. 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 11 through the magnet holding member 4.

(56) 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.

(57) Furthermore, in the third embodiment, eddy current occurs on the inner peripheral surface of the cylinder portion 1c, which is distant from the rotational center from among the disk portions 1a and 1b and the cylinder portion 1c, 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 1c of the brake member 1 and the permanent magnets 5, it is possible to further improve the braking efficiency.

Fourth Embodiment

(58) 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 embodiment according 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.

(59) 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 1a and 1b and the inner peripheral surface of the cylinder portion 1c 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. 5C). 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.

(60) 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 1a and 1b are indicated with arrows with dotted lines.

(61) 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 1a and 1b and the cylinder portion 1c, 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.

(62) 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 1a and 1b and the cylinder portion 1c (brake member 1). This causes eddy current to be generated on the inner surface of each of the disk portions 1a and 1b and the inner peripheral surface of the cylinder portion 1c. 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 1a and 1b of the brake member 1 and the inner peripheral surface of the cylinder portion 1c 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.

(63) 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.

(64) Furthermore, in the fourth embodiment, eddy current occurs on the inner surface of each of the disk portions 1a and 1b 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 1a and 1b and the inner peripheral surface of the cylinder portion 1c, 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 1a and 1b and the cylinder portion 1c of the brake member 1, it is possible to further improve the braking efficiency.

Fifth Embodiment

(65) 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.

(66) 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.

(67) 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.

(68) 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 1a and 1b 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.

(69) 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 time 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 the 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 1, and prevent the temperatures of the brake member 1 from rising.

(70) 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.

Sixth Embodiment

(71) 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.

(72) 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 member 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 1b in association with movement of the brake pad 8b on the rear side toward the disk portion 1b 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.

(73) 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 1) on the rear side, and continuously detects temperatures of the disk portion 1b. At this time, the actuator controlling unit 23 monitors temperatures of the disk portion 1b detected by the temperature sensor 21, and stops actuating the actuator 9 if the temperature exceeds a predetermined temperature. Once the actuation of the actuator 9 is stopped, the brake pads 8a and 8b and the temperature sensor 21 move away from the disk portion 1b, and are switched into a non-braking state. As a result, the brake member 1 rotates together with the rotating shaft 11, 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.

(74) 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.

(75) 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.

Seventh Embodiment

(76) 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 suppressing an increase in temperatures of the brake member 1, and by modifying the configuration of the retarding device according to the first embodiment.

(77) 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 1b in association with movement of the brake pad 8b on the bask side toward the disk portion 1b on the rear side of the brake member 1.

(78) 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.

(79) 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 1b (brake member 1) on the rear side. Thus, the disk portion 1b 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.

(80) 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.

Eighth Embodiment

(81) 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 shown. The retarding device according to the eighth embodiment shown in FIG. 9 is obtained by modifying the configuration of the retarding device according to the first embodiment.

(82) 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.

(83) 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 1a and 1b 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 1b 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, plural times, an electrically conductive wire having high electrical conductivity such as a copper wire.

(84) 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 1b on the rear side, and is connected with a terminal 29 disposed on the external surface of this disk portion 1b. The wire-wound coils 27 and the terminal 29 described above rotate integrally with the disk portion 1b (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.

(85) 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 1a and 1b (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 1a on the front side and a magnetic field from the permanent magnets 5 acting on the inner surface of the disk portion 1b 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 1a and 1b, 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.

(86) 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 1a and 1b (brake member 1). This causes a change in both the magnetic field from the permanent magnets 5 acting on the inner surface of the disk portion 1a on the front side and the magnetic field from the permanent magnets 5 acting on the inner surface of the disk portion 1b on the rear side and the wire-wound coils 27. On the disk portion 1a 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 1b on the rear side, the magnetic field from the permanent magnets 5 changes, whereby eddy current occurs 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) from 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.

(87) 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 1a and 1b 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.

(88) It should be noted that the wire-wound coils 27 as described above may be configured to be embedded in the disk portion 1a on the front side, or may be configured to be embedded in both of the disk portions 1a and 1b. Furthermore, the wire-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 1c.

(89) 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.

(90) For example, in each of the embodiments described above, descriptions have been made of the case where the disk portions 1a and 1b 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 1a and 1b or the inner peripheral surface of the cylinder portion 1c.

(91) 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 1a and 1b and the inner peripheral surface of the cylinder portion 1c.

(92) Furthermore, in each of the embodiments described above, descriptions have been made of the case where the brake member 1 includes the disk portions 1a and 1b and the cylinder portion 1c, 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.

(93) 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.

(94) 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 1a and 1b, the actuator controlling unit (not shown) that stop actuating the actuator 9 in the case where temperatures of the disk portions 1a and 1b 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 1a and 1b.

(95) Furthermore, as for the friction brake that brings the brake member 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

(96) 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

(97) 1: brake member

(98) 1a, 1b: disk portion (eddy-current generating member)

(99) 1c: cylinder portion (eddy-current generating member)

(100) 2: radiating fin

(101) 4: magnet holding member

(102) 4a: magnet holding ring

(103) 4b: ferromagnetic member

(104) 5: permanent magnet

(105) 7: brake caliper

(106) 8a, 8b: brake pad

(107) 9: electrically driven direct-acting actuator

(108) 10: electrically driven motor

(109) 11: rotating shaft

(110) 12: connecting shaft

(111) 13: sleeve

(112) 15a, 15b: bearing

(113) 17: bracket

(114) 18: bearing

(115) 20a, 20b: impeller

(116) 21: temperature sensor

(117) 22: temperature sensor holder

(118) 23: actuator controlling unit

(119) 24: water cooling body (cooling member)

(120) 25: water-cooling-body holder

(121) 26: water passage

(122) 27: wire-wound coil

(123) 28: electrically conductive wire

(124) 29: terminal

(125) 30: electric contact point

(126) 106: brake disk

(127) 120: magnet cover