| 摘要 |
<p>A reverse brake mechanism (10) for an electrically assisted bicycle includes a crankshaft (40). When the crankshaft (40) is rotated forward, it causes a drive ring (50) to rotate the chainwheel (30) forward and then causes the chainwheel (30) and the drive ring (50) to rotate a respective magnet holder synchronously, maintaining polar alignment between two magnets at the two magnet holders and allowing a motor (20) to output an assisted power. When the crankshaft (40) is rotated backward, it causes the drive ring (50) to rotate relative to the chainwheel (30), generating a time lag in which one magnet holder is driven by the drive ring (50) to rotate relative to the other magnet holder, causing polar misalignment between the magnets at the two magnet holders. Thereafter, magnetic sensors (80) sense the variation of the magnetic field and then interrupt the output of the motor (20), and finally, the drive ring (50) drives the chainwheel (30) to rotate backward, achieving a braking effect.</p> |
