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Slashing part counts: DENSO develops low-cost fuel-injection system for small motorcycles

Global automotive supplier DENSO Corporation (Kariya, Aichi prefecture, Japan) has developed a new electronic fuel-injection system for small motorcycles called DIET-FI (DENSO Intelligent Economical Technology-Fuel Injection).

DIET-FI is the world's first fuel-injection system that doesn't use a throttle position sensor or engine temperature sensor. Instead, it uses newly developed control technologies that ensure the same fuel economy and environmental performance as conventional fuel-injection systems, which should go a long way toward cutting costs.

DENSO's new electronic fuel-injection system for small motorcycles, called DENSO Intelligent Economical Technology-Fuel Injection (DIET-FI), has only five main components.



Usually, fuel-injection systems are only used in larger motorcycles, but in recent years there has been a growing need to apply these systems to smaller motorized bikes up to the size of 150cc that are used in emerging markets, such as China.

DENSO researched this trend and engineered a low-cost fuel-injection system that delivers similar fuel economy and environmental performance as conventional systems but with fewer components.

Fuel-injection systems for motorcycles consist of sensors, actuators, and electronic control units (ECUs) to ensure high-precision control of the air-fuel ratio. The optimal fuel injection volume is calculated based on the air volume, engine condition, etc., which are detected by sensors. The fuel from the fuel pump is fed into the engine by injectors with high precision.

The widespread application of fuel-injection systems to small motorcycles will require smaller components, simpler systems, fewer components, and lower cost compared with four-wheelers and large motorcycles.

DENSO's DIET-FI has five fewer components than conventional systems. Through extensive research, DENSO developed control technologies that were able to eliminate the throttle position sensor, intake air temperature sensor, engine temperature sensor, ISC idle speed control step motor, and fall detection sensor. Specific compensation technologies include a temperature estimation control that integrates a thermistor into an electronic control unit and a fuel metering control to determine acceleration/deceleration using an intake air pipe pressure sensor.

Eliminated parts from conventional fuel injection system are shown in red.



DIET-FI is currently manufactured by Gongcheng DENSO (Chongqing) Co., a group company that manufactures motorcycle components, and supplied to Wuyang-Honda Motors (Guangzhou) Co.

Source: DENSO

Published July 2014

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