DENSO Develops an Electric Air-conditioning System for Hybrid Buses

DENSO Develops an Electric Air-conditioning System for Hybrid Buses

Power consumption of system’s compressor is reduced by half

KARIYA (Japan) ― DENSO Corporation has developed a smaller, lighter and more efficient air-conditioning system for hybrid buses. The air-conditioning system has an integrated electric compressor, which uses about 50 percent less power compared to DENSO’s previous system. Also, the new air-conditioning system has an improved operating efficiency and provides greater comfort to passengers. The first vehicle to use the new system is the Hino Blue Ribbon City Hybrid, a bus launched by Hino Motors, Ltd., in June 2010.

“With an increased awareness to the environment, buses, which are a key means of public transportation, must be more fuel efficient,” said Akio Shikamura, senior managing director responsible for DENSO’s Thermal Systems Business Group. “DENSO will continue to develop products that contribute to both passenger and driver comfort and environment.”

Like traditional buses that use combustion engines, hybrid buses use conventional air-conditioning systems with a compressor driven by an engine belt, so when the engine stops, the air-conditioning system no longer operates. DENSO’s new system uses battery power, which allows the air-conditioning system to operate while the engine is stopped. Also, engine-powered compressors must be located close to the engine; however, bus cooler systems are usually mounted on the roof, which requires long plumbing to connect with the compressor. With DENSO’s system, the pipes can be shortened, which improves the ease of installation and decreases the weight of the new air-conditioning system.

Also, unlike engine-powered compressors that are driven by an engine belt, the electric compressor can be precisely controlled according to the situation, which improves operational efficiency and reduces variation in the temperature to provide greater comfort.

“With the electrically controlled compressor and the smaller system size, the power consumption of the compressor is reduced by about 50 percent compared to DENSO’s previous systems,” said Shikamura. “Moreover, the new air-conditioning system, which can operate while the engine is stopped, will contribute to the widespread use of start and stop systems.”

The new air-conditioning system is Japan’s first mass-produced, electric air-conditioning system integrating an electric compressor with a built-in inverter.

DENSO Corporation, headquartered in Kariya, Aichi prefecture, Japan, is a leading global automotive supplier of advanced technology, systems and components in the areas of thermal, powertrain control, electric, electronics and information and safety. Its customers include all the world’s major carmakers. Worldwide, the company has more than 200 subsidiaries and affiliates in 34 countries and regions (including Japan) and employs approximately 120,000 people. Consolidated global sales for the fiscal year ending March 31, 2010, totaled US$32.0 billion. Last fiscal year, DENSO spent 9.1 percent of its global consolidated sales on research and development. DENSO common stock is traded on the Tokyo and Nagoya stock exchanges. For more information, go to www.globaldenso.com, or visit our media website at www.densomediacenter.com.