Vehicle technology company and supplier to the electric bike business ZF has created a new super-fast speed sensor to compliment the ongoing trend of ABS integration into high-spec electric bikes and speed pedelecs.
With electric bike speeds a talking point of late, including at key seminars at the Eurobike show, the need for high-spec sensors has been speculated upon, in particular with certain automotive manufacturers pushing to tear up the current frameworks in a bid to grab a slice of the market.
Based on Hall technology, the sensor in combination with an external, ferromagnetic speed disk achieves a high-resolution speed measurement. The sensor targets the slot structure of the speed disc and, depending on the number of slots, it transmits up to 50 or more speed signals per wheel revolution. In practice, this leads to a finer and quicker response from the e-bike drive.
The ABS system also benefits from the high resolution in speed. With the precise speed values of both wheels, the ABS control unit can adjust the wheels to each other and brake them in a controlled manner.
The extremely compact design (21.75mm long x 9.35mm in diameter) of the sensor fulfills the necessary requirements for the use in e-bikes that most manufacturers will be conscious of. The speed sensor is based on the principle of the Hall effect and therefore it is contactless and wear-free. The differential measurement of the magnetic flux also increases the robustness of the sensor against vibrations.
Depending on the customer’s requirements the contact via connector, as well as the cable length, can be preselected individually. The sensor requires a constant voltage supply of 6.5 – 20 VDC and measures frequencies between 1 and 2,500 Hz. They are designed for a temperature range from -25 °C to + 85 °C to fulfill the declaration of conformity in the e-bike industry.