Old news, but...
July 5, 2005
Honda Announces Development of New Honda Hybrid System Featuring 3-Stage i-VTEC + IMA

—New Civic Hybrid powerplant scheduled for fall 2005 introduction— Watch Video

TOKYO, Japan, July 5, 2005 - Honda Motor Co., Ltd. announced that it has developed a New Honda Hybrid System, which features a 3-stage i-VTEC engine that employs Honda’s intelligent VTEC (Variable Valve Timing and Lift Electronic Control) system to provide three stages of valve timing (low-rpm, high-rpm, and cylinder idle mode), combined with Honda’s IMA (Integrated Motor Assist) system that has been made significantly more compact and efficient. The New Honda Hybrid System will be introduced in the all-new Civic Hybrid, to be launched this fall.

New Honda Hybrid System (3-stage i-VTEC + IMA) cut-away model

The New Honda Hybrid System employs intelligent engine functions and a more efficient IMA system to achieve an approximate 20% increase in system output over the current system (1) and the powerful performance of a 1.8-liter engine while improving fuel economy by 5% (2), reducing the system size by 5% and attainting a world-leading level of emissions performance. The system offers significantly improved performance and fuel economy over the current system.
1) Current Civic Hybrid system
2) Compared to current Civic Hybrid when driven in 10-15 mode

The 3-stage i-VTEC engine employs three hydraulic pathways to couple and uncouple five rocker arm assemblies, providing three stages of valve control depending on the driving conditions to achieve a combination of responsive driving and fuel economy. During deceleration when the cylinders are idle, combustion in all four cylinders is halted and the cylinders sealed shut, reducing pumping losses caused by engine aspiration for a 10% improvement in recovery of braking energy compared to the current model (3). Virtually everything possible has been done to reduce friction as well, including the use of aluminum die-cast pistons, which feature low thermal expansion for less friction under high-temperature conditions, ion-plated piston rings, and plateau honing of the cylinder walls for a smoother surface.

Honda’s independently developed electric motor employs coils with high-density windings and high-performance magnets to attain output 1.5 times that of the current model while maintaining the same size. The inverter used to control motor speed—also independently developed and manufactured by Honda—is integrated with the motor’s ECU for more precise digital control, contributing to even greater motor efficiency and fuel economy. Battery output has been increased by around 30% over the current model (3), while a more compact, custom designed battery storage box offers increased cooling performance and vibration resistance for improved long-term reliability.
3) Current Civic Hybrid

Also, a dynamic regenerative braking system is employed that hydraulically controls the brakes based on the amount of brake regeneration. This permits maximum braking regeneration along with smooth deceleration that conforms to brake-pedal pressure. The air conditioner features a hybrid compressor that is powered by both the engine and the motor. When the engine is in Idle Stop mode the compressor is powered by the motor; if rapid cooling is required it is powered by the engine and motor combined. When the temperature is stable it runs off the motor alone, for both improved comfort and fuel savings.
*All values are based on Honda in-house calculations

New Honda Hybrid System Modes of Operation

• Vehicle stationary
The engine is turned off and fuel consumption is zero.

• Startup and acceleration
The engine operates in low-speed valve timing mode, with motor assist.

• Rapid acceleration
The engine operates in high-speed valve timing mode, with motor assist.

• Low-speed cruising
The valves of all four of the engine’s cylinders are closed and combustion halted. The motor alone powers the vehicle.

• Gentle acceleration and high-speed cruising
The engine operating in low-speed valve timing mode powers the vehicle.

• Deceleration
The valves of all four of the engine’s cylinders are closed and combustion halted. The motor recovers the maximum amount of energy released during deceleration and stores it in the battery.

New Honda Hybrid System Operation Outline