Power Assist Mode: Crank sensor
- Thread starter UrbanPuma
- Start date
There's several elements to this, first the rotation sensing, then whether the sensing speed is used in any way, and also whether the power is controlled by throttle and pedelec or throttle or pedelec.
The rotation sensing is normally done by either a ring of magnets passing a Hall pickup sensor, or a spoked ring passing a photocell and infrared sensor pair. In both cases, when in pedelec mode, switching on and off due to rotation has to be sensed for power to be delivered.
Some systems use the spacing of magnets or spokes passing to register the speed of rotation, this then being used to phase the power delivery. For example, European law calls for a bike to phase down power from around 13 mph on, before cutting at 15.5 mph, and the rotation speed sensing can be used for that. In the case of powerful motors, the power cutting suddenly at 15.5 mph could be very unpleasant, so phasedown is used to prevent sharp changes in power. The most sophisticated of these power phasing systems is in the Panasonic motor units used in the Lafree Twist and Gazelle Easy Glider bikes amongst others, and they have no throttle.
In some bikes the throttle is completely independent in throttle only mode, and off when in pedelec mode. In some others, the throttle operates all the time, even when in pedelec mode, so it always has to be used.
Some larger Powacycle models combine throttle with pedelec, but I don't know the arrangement of your Urban Puma folder which is made by a different factory.
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The rotation sensing is normally done by either a ring of magnets passing a Hall pickup sensor, or a spoked ring passing a photocell and infrared sensor pair. In both cases, when in pedelec mode, switching on and off due to rotation has to be sensed for power to be delivered.
Some systems use the spacing of magnets or spokes passing to register the speed of rotation, this then being used to phase the power delivery. For example, European law calls for a bike to phase down power from around 13 mph on, before cutting at 15.5 mph, and the rotation speed sensing can be used for that. In the case of powerful motors, the power cutting suddenly at 15.5 mph could be very unpleasant, so phasedown is used to prevent sharp changes in power. The most sophisticated of these power phasing systems is in the Panasonic motor units used in the Lafree Twist and Gazelle Easy Glider bikes amongst others, and they have no throttle.
In some bikes the throttle is completely independent in throttle only mode, and off when in pedelec mode. In some others, the throttle operates all the time, even when in pedelec mode, so it always has to be used.
Some larger Powacycle models combine throttle with pedelec, but I don't know the arrangement of your Urban Puma folder which is made by a different factory.
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That's the similar to the larger models then, operation as described. I know the full size bikes employ a degree of power phase down as the speed reaches the limit, but I don't know if that's true of yours. You can probably tell if it does fall away as it nears it's limit.
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No, the primary purpose of the sensor is to detect if pedalling is happening. Any sort of speed detection is secondary, and they aren't usually used for speed limiting, only the power phasedown where necessary as I've said.
Most bikes speed limiting is just by the motor being at it's maximum at around the legal limit or as near as it can get to that, so no speed limiting necessary. That's true of yours as well.
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Most bikes speed limiting is just by the motor being at it's maximum at around the legal limit or as near as it can get to that, so no speed limiting necessary. That's true of yours as well.
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