Abstract:
A braking assembly with a manageable self-generating power energy is disclosed. A pair of curved braking plates are disposed between the stator and the rotor. A pulling mechanism is provided on the stator for pulling two free ends of two curved braking plates. A plurality of first permanent magnets are fixed to the outer circumferential surface of each the curved braking plates. Moreover, at least one power-generating coil is provided on a stator of the braking assembly nearby the permanent magnets for generating an AC voltage when the rotary central shaft rotates. A control circuit receives the AC voltage and rectifies and stabilizes the AC voltage to generate a DC voltages to drive the motor of the pulling mechanism to rotate, and by means of the pulling mechanism, the braking force of the braking assembly is controlled.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a braking force regulating structure for a braking device, and more particularly to a braking assembly with a manageable self-generating power energy. 
   2. Description of the Prior Art 
   A conventional braking assembly, such as the brake for an exercise bike, mainly includes a rotor and a stator. Two corresponding curved braking plates are pivotally connected to the stator, and a plurality of curved permanent magnets are provided at an outer circumferential surface of the curved braking plates, such that outer circumferentially surfaces of the curved permanent magnets face toward an inner circumferential surface of the rotor with a proper air clearance left between them. When the rotor rotates, an eddy current is produced as a result of an induction between the permanent magnets and the rotor and consequently, a dragging force will be applied the rotor. The smaller the air clearance between the permanent magnets and the rotor is, the stronger the induced eddy current is, and the larger the produced dragging/braking force is. Accordingly, this dragging force can be used as the resistance of sporting equipment. 
   To regulate the braking force, the conventional braking assembly includes a cable that can be manually operated to pull one of two ends of each curved braking plate and thereby adjust a distance of the air clearance between the outer circumferential surfaces of the permanent magnets and the inner circumferential surface of the rotor and accordingly, the braking force of the braking assembly. 
   Other similar types of conventional braking structures are also found in prior patents. U.S. Pat. No. 6,360,855 discloses a brake for an exercise bike. The brake includes a first and a second disc-shaped plate, a center shaft extended between the two disc-shaped plates, and a plurality of bars and rollers located between the two disc-shaped plates to space the latter from each other by a predetermined distance. The brake also internally includes two curved plates having magnets provided on outer circumferential surfaces thereof. The two curved plates are pivotally connected at an end to and between the two disc-shaped plates, and connected at the other end to a pulling cord. When the pulling cord is pulled, a braking effect of the brake may be changed. 
   A disadvantage of the above-mentioned conventional brakes is that it must be manually operated to regulate the braking force thereof. To change the manually operated brake to a power-controlled brake, it is necessary to connect with an external power source so as to supply power to a driving mechanism of the brake. This requirement restricts the mounting of the brake to a position close to a power supply, otherwise wiring to power source is needed. 
   Therefore, it is desired to release the conventional brake from the limitations of being mounted close to the external power source, so that the brake may be conveniently used at any place. 
   To meet the above requirement, there is developed a self-excitation type power-generating braking structure. U.S. Pat. No. 6,084,325 discloses a brake device with a combination of power-generating and eddy-current magnetic resistance, in which a power-generating coil is provided to one side of a flywheel. When the flywheel rotates, the power-generating coil is caused to generate electrical energy to produce a braking force. However, the power-generating coil must work with the large flywheel to produce the required electrical energy and could not be integrated into the braking device. This results in a complicate structure of the braking device and troublesome assembling and mounting thereof. 
   It is therefore tried by the inventor to develop a braking assembly with self-generating power energy to eliminate the drawbacks existed in the conventional brakes. 
   SUMMARY OF THE INVENTION 
   A primary object of the present invention is to provide a braking assembly with self-generating power energy. The braking assembly has power-generating function to provide electric power energy needed by an internal pulling mechanism and an external control panel thereof, so that the braking assembly can be conveniently mounted for use without the need of connecting to an external power supply. 
   To achieve the above objects, in accordance with the present invention, there is provided a braking assembly with a manageable self-generating power energy. A pair of curved braking plates are disposed between the stator and the rotor. A pulling mechanism is provided on the stator for pulling two free ends of two curved braking plates. A plurality of first permanent magnets are fixed to the outer circumferential surface of each the curved braking plates. Moreover, at least one power-generating coil is provided on a stator of the braking assembly nearby the permanent magnets for generating AC voltage when the rotary central shaft rotates. A control circuit receives the AC voltage and rectifies and stabilizes the AC voltage to generate a DC voltage to drive the motor of the pulling mechanism to rotate, and by means of the pulling mechanism, the braking force of the braking assembly is controlled. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein 
       FIG. 1  is a plan view of a braking assembly with a manageable self-generating power energy according to a first embodiment of the present invention; 
       FIG. 2  is a plan view of the braking assembly according to a second embodiment of the present invention; 
       FIG. 3  is a circuit block diagram of the present invention; 
       FIG. 4  is a schematic view showing a regulation of power under the control of a power management circuit of  FIG. 3 ; 
       FIG. 5  is plan view of the braking assembly according to a third embodiment of the present invention; 
       FIG. 6  is plan view of the braking assembly according to a fourth embodiment of the present invention; and 
       FIG. 7  is a cross-sectional view of a friction electric generator of the braking assembly. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Please refer to  FIG. 1  that is a plan view of a braking assembly according to a first embodiment of the present invention. As shown, the braking assembly of the present invention mainly includes a rotary central shaft  10 , a rotor  11  rotating along with the rotary central shaft  10 , a stator  20 , and two curved braking plates  21 . The rotor  11  may be made of cast iron, forge iron, or cast steel. 
   Two adjacent ends of the two curved braking plates  21  are pivotally connected via pivoting means, such as pivot shafts  20   a  and  20   b , to predetermined positions on an outer circumferential surface of the stator  20 , and the other two adjacent ends of the two curved braking plates  21  are left suspended, so that outer circumferential surfaces of the curved braking plates  21  face toward an inner circumferential surface of the rotor  11 . By regulating an air clearance between the outer circumferential surfaces of the curved braking plates  21  and the inner circumferential surface of the rotor  11 , a magnitude of a braking force of the braking assembly may be controlled. 
   The curved braking plates  21  are fixedly provided on respective outer circumferential surfaces with a plurality of permanent magnets  22 . The permanent magnets  22  have curved outer surfaces facing toward the circumferential inner surface of the rotor  11 . In the present invention, there are permanent magnets  12  continuously arranged around an outer surface of the rotary central shaft  10 , so that the north poles and the south poles alternate around the rotary central shaft  10 . A first power-generating coil  23  is provided on the stator  20  at a position close to the permanent magnets  12 . 
   In addition, the stator  20  also has a pulling mechanism  30  provided thereon for regulating the air clearance between the curved braking plates  21  and the rotor  11 . The pulling mechanism  30  includes two pulling cords  34   a ,  34   b  which are fixedly connected at respective one end to free ends  20   c ,  20   d  of the two curved braking plates  21 , and at respective another end to a transmission shaft  311  of the motor  31  for dragging. The pulling cords  34   a ,  34   b  may be, for example, two linking bars or two ropes for connecting two free ends  20   c ,  20   d  of the curved braking plates  21  and the driving shaft  311 . By pulling or releasing the pulling cords  34   a ,  34   b , the air clearance between the outer circumferential surfaces of the curved braking plates  21  and the inner circumferential surface of the rotor  11  is regulated, and thereby the braking force of the braking assembly is controlled. 
   As can be seen from  FIG. 1 , each of the two curved braking plates  21  is provided at a predetermined position on an inner circumferential surface with a compression spring  35  to radially extend between the curved braking plate  21  and the stator  20 , so that the compression spring  35  provides a radially outward restoring force to the curved braking plate  21 . When the rotor  11  stops rotation, the curved braking plates  21  restore to its normal position where the dragging force is minimal to avoid damage to the user. 
   With the above arrangements, when the rotary central shaft  10  rotates, it brings the rotor  11  to rotate synchronously. At this point, excitation eddy currents are generated between the rotor  11  and the permanent magnets  22  mounted on the curved braking plates  21  fixed to the stator  20  to brake the rotor  11 . 
   And, while the rotary central shaft  10  rotates, an AC voltage is produced by the power-generating coil  23  due to a magnetic induction between the power-generating coil  23  and the permanent magnets  12  provided on the outer surface of the rotary central shaft  10 . 
     FIG. 2  is a plan view showing the second embodiment. The second embodiment is substantially similar to the first embodiment, and like reference numerals are used to identify elements that are similar or identical in the two embodiments. However, the second embodiment is different to the first embodiment in that the pulling mechanism  30  comprises a reduction gear set  32  which includes a toothed disc  33 . Two pulling cords  34   a ,  34   b  are fixedly connected at respective one end to two diametrically opposite points on the same side surface of the toothed disc  33 , and at respective another end to free ends  20   c ,  20   d  of the two curved braking plates  21 . The pulling cords  34   a ,  34   b  may be, for example, two linking bars or two ropes for connecting two free ends  20   c ,  20   d  of the curved braking plates  21  and the pulling mechanism  30 . 
   In this embodiment, a plurality of power-generating coils, the first, second, third, fourth, fifth and sixth power-generating coil  23 ,  23   a ,  23   b ,  23   c ,  23   d ,  23   e , are provided on the stator  20  at positions close to the permanent magnets  12 . While the rotary central shaft  10  rotates, AC voltage is produced by each of the power-generating coils  23 ,  23   a ,  23   b ,  23   c ,  23   d ,  23   e  due to the magnetic induction between the first, second, third, fourth, fifth and sixth power-generating coil  23 ,  23   a ,  23   b ,  23   c ,  23   d ,  23   e  and the permanent magnets  12  provided on the outer surface of the rotary central shaft  10 . 
   The produced AC voltage generated by each of the second, third, fourth, fifth and sixth power-generating coils  23   a ,  23   b ,  23   c ,  23   d ,  23   e  may be rectified and stabilized by conventional rectifier and stabilizer to generate DC voltages and provided in serial to a motor  31  of the pulling mechanism  30  to increase the working power. This is critical for maintaining a steady and sufficient working power, especially when the power supply from the first power-generating coil  23  is not enough. 
   The powers generated by the power-generating coils  23   a ,  23   b ,  23   c ,  23   d ,  23   e  may also be used for other purposes. Take for an example. The powers may be provided to power a microprocessor or other electronic elements on a control circuit of a circuit board  200 . The power is then conveyed from the circuit board  200  to the motor  31  by a cable  201  connected between the circuit board  200  and motor  31 . Besides, the powers generated by the power-generating coils  23   a ,  23   b ,  23   c ,  23   d ,  23   e  may be provided to power the indicator and backlight and display unit of the control circuit or other exercise equipment. 
   Please refer to  FIG. 3  which is a circuit block diagram of the present invention. As shown, the powers generated by the power-generating coils  23 ,  23   a ,  23   b ,  23   c ,  23   d ,  23   e  is regulated and distributed by a power management circuit  24 . 
   When the present invention includes only one power generating coil, for example the first power generating coil  23 , the power generated by the first power generating coil  23  flows under the control of the power management circuit  24  to the motor  31  and a control panel  27 . The control panel  27  comprises a charging circuit  271 , a rechargeable battery  272 , a LED indicator and backlight  273  and a display unit  274 . 
   The powers generated by the power generating coils are supplied to the power management circuit  24  and then to a control circuit  25  which drives and controls the rotation of the motor  31 . The control circuit  25  may comprises a conventional rectifier and stabilizer for rectifying and stabilizing the AC voltages to provide a DC voltage and control the motor  31  to rotates clockwise or counterclockwise. The control circuit  25  is connected with a regulating unit  26  for regulating and setting the rotation angle of the motor  31 . 
   When the motor  31  rotate clockwise, the reduction gear set  32  meshing with the transmission shaft  311  of the motor  31  drives the toothed disc  33  to rotate clockwise and pull the two pulling cords  34   a ,  34   b . At this point, the two curved braking plates  21  are pulled by the pulling cords  34   a ,  34   b  toward the stator  20 , and the air clearance between outer surfaces of the permanent magnets  22  on the curved braking plates  21  and the inner circumferential surface of the rotor  11  is increased to reduce the brake force of the braking assembly. 
   And, when the motor  31  rotates counterclockwise, the pulling of the curved braking plates  21  by the pulling cords  34   a ,  34   b  is released, and the restoring force of the compression springs  35  pushes the curved braking plates  21  radially outward to reduce the air clearance between outer surfaces of the permanent magnets  22  on the curved braking plates  21  and the inner circumferential surface of the rotor  11 , and the brake force of the braking assembly is increased. That is, the brake force of the braking assembly of the present invention may be electrically automatically regulated. 
   When the present invention includes two or more power generating coils, the power generated by one of the power generating coils is supplied via the power management circuit  24  to the charging circuit  27 , rechargeable battery  272 , LED indicator and backlight  273  and display unit  274  of the control panel  27 , while the power from the other power generating coil is supplied to the motor  31 . However, the motor  31  may not work for most of the time, for example 90% of the time. When the motor suspends rotation, under the control of the power management circuit  24 , the power to the motor is supplied to the rechargeable battery  272  via the charging circuit  271 . 
   As shown in  FIG. 3 , the power management circuit  24  is capable to manage individually the powers generated by the power generating coils  23 ,  23   a ,  23   b ,  23   c ,  23   d ,  23   e . Please refer to  FIG. 4  which shows a regulation of power under the control of the power management circuit  24  of  FIG. 3 . 
   In the period P 1  when the rotation speed in RPM of the rotary central shaft  10  is not equal to zero, power is supplied to the motor  31  for maintaining the normal operation of the motor  31 . Also, power is steadily supplied to the charging circuit  271 , rechargeable battery  272 , LED indicator and backlight  273  and display unit  274 . 
   In the period P 2  when the rotation speed in RPM of the rotary central shaft  10  is equal to zero, from the time t 1  the rotation speed becoming zero to a predetermined time t 2 , power supply to the LED indicator and backlight  273  is terminated under the control of the power management circuit  24 . Anyway, power supply to the display unit  274  is maintained. Thereby, power can be efficiently saved. When the rotary central shaft  10  stops rotation for a predetermined time t 3 , under the control of the power management circuit  24 , power supply to the display unit  274  is terminated. In other words, the control panel  27  enters a sleeping mode after t 3 . The power management is helpful to the user who temporarily pauses his action. 
     FIG. 5  shows a plan view of the braking assembly according to a third embodiment. The third embodiment is substantially similar to the first embodiment, however, the third embodiment is different to the first embodiment in that the power generating coil  23  is replaced by a friction electric generator  41  and that no permanent magnet is provided on the outer surface of the rotary central shaft  10 . The friction electric generator  41  comprises a coil and a transmission shaft disposed therein. Also, the friction electric generator  41  includes a friction wheel  411  projected from an outer end of the friction electric generator  41  and contacting the inner circumferential surface of the rotor  11 . When the rotor  11  rotates, the friction wheel  411  is turned to rotate, and in turn drives the transmission shaft and coil to generate power. 
   With reference to  FIG. 6 ,  FIG. 6  shows a fourth embodiment of the braking assembly. The fourth embodiment is substantially similar to the third embodiment, however, the fourth embodiment is different to the third embodiment in that the power generating coil  23  is replaced by a friction electric generator  41  and that the pulling mechanism  30  comprising a reduction gear set  32  similar in structure to that shown in  FIG. 2 . 
   Please refer to  FIG. 7  which is a cross-sectional view of the friction electric generator  41 . As shown, the friction electric generator comprises a friction wheel  411 , a transmission shaft  412  and a coil  413 . When the friction wheel  411  is turned by the rotor  11 , the friction wheel  411  drives the transmission shaft  412  to rotate, and hence power is generated by the coil  413 . 
   While the present invention has been described with reference to the specific embodiments, the description is illustrative of the invention and is not to be construed as limiting the invention. Therefore, various modifications to the present invention can be made to the preferred embodiments by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.