Advantages and application benefits

Uses a highly sensitive differential Hall IC. The sensor can output highly accurate, high-level voltage waveforms from the lowest speed to full throttle, even when the air gap is expanded by as much as 2mm (refer to “Revolution speed vs. output voltage ratio characteristics” below).

Comparison example of characteristics and waveforms

Also, as shown in the list of environmental durability properties and an example of duty ratio temperature characteristics, the sensor can respond to any temperature from -40 to +150°C , and is resistant to thermal shock, vibration, shock, and achieving durability that far exceeds competitors in even the toughest reliability tests. As for waterproofing (ability to withstand exposure to water), the sensor’s independently designed seal construction provides industry-leading long-term reliability in ATVs and motorcycles.

Environmental durability properties/Duty ratio character

Automobile harnesses use relatively low voltages, but in ATVs and motorcycles, because various control parts such as coils and relays rely on direct power feed from the battery, destructive surge noise is often generated.

To maintain highly accurate sensor capabilities in such a harsh electromagnetic environment, special circuits with superior surge absorption abilities have been installed. As well as displaying excellent radiofield resistance, these sensors also show strong anti- noise properties that pass the JASO Transient Voltage Characteristic Test D001-94.

Example of comparison with analog type

Responding to next-generation FI system needs

To assist with efforts to develop 4-stroke FI engines for motorcycles, TDK has committed itself to technological improvements that support “improved ultra low-speed revolution detection capabilities” and “jitter minimization”.

Also, to support the development of a practical FI system for 50cc class scooters and minibikes, TDK is taking the environmental durability and anti-noise design technology applied in the ATV sector to develop new sensor structure which allows greater downsizing, weight-saving, and cost-saving than before and a model using the direct coupler method.

Direct coupler method model

Elaborate design-in support system

In the move to bring 4-stroke FI to motorcycles, specifically to the moderately priced 50cc class, a lot of efforts are being made to address a variety of cost - and construction - related issues. To enable quick and flexible support for these efforts, a system of development for gear-tooth sensors also needs to be established and strengthened.

Specific requirements include a quick development environment, in which gear-tooth sensor design specifications, such as the alignment of the magnetic detector's Hall element, internal magnet shapes, and magnetic properties, are optimized for the shape and material of the gear that is being detected. TDK has established a powerful support system for this kind of design-in system that takes full advantage of our vast magnetic field simulation models, which are backed by many years of superior performance.

Also, for motorcycles currently being mass produced, an elaborate improvement support system that is closely linked to the mass production line is being developed. This system not only addresses various requests for improvements, such as jitter reduction and increased sensor accuracy, but also includes the use of magnetic simulations for quick diagnosis, gear shape inspections, and improvement proposals when inconveniences occur that demand immediate attention.

Example of simulation model

(a) Differential Hall ICs have two sensing points. The flux change mode of each point varies depending on the mutual balance of a variety of factors including gear span, groove depth, gear tooth shape, the magnet (thickness, area, shape), the absence or presence of yoke, and Hall element alignment.

(b) TDK has accumulated a number of simulation models corresponding to a wide variety of gear shapes. Beginning with the initial design phase of the engine, TDK proposes the ideal combinations of a variety of factors including gear shape, and supports the development of high-precision, compact and lightweight FI systems.