Honda Introduces New Hybrid System for the Civic
5 July 2005
Honda has revealed some of the specifications for its new Honda Hybrid System, which will be introduced in the new Civic Hybrid being launched this fall. The new system delivers 20% more power with an estimated 5% better fuel economy than the current Civic Hybrid.
The new system features a new 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 a more compact and efficient IMA (Integrated Motor Assist) system. (Hybrid system shown at right—Click to enlarge.)
The 3-stage i-VTEC engine uses 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.
When the cylinders are idle during deceleration, 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 Civic hybrid.
The new engine features a number of friction-reducing technologies, including the use of aluminum die-cast pistons (featuring 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 is some 30% greater than that of the current model, while a more compact, custom designed battery storage box offers increased cooling performance and vibration resistance for improved long-term reliability.
The dynamic regenerative braking system 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.
The various modes of operations for the new hybrid system are:
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.
|Specifications of New Honda Hybrid System|
|Power source||Engine||Engine type and number of cylinders||Water-cooled in-line 4-cylinder|
|Bore × stroke(mm)||73.0 × 80.0|
|Electric motor||Electric motor type||AC synchronous drive (Ultra-thin DC brushless motor)|
|Rated voltage||158 v|
|Performance||Engine||Max. output||70 kW (100 hp)/6,000 rpm|
|Max. torque||123 Nm (91 lb-ft)/4,500 rpm|
|Electric motor||Max. output||15 kW (20 hp)/2,000 rpm|
|Max. torque||103 Nm (76 lb-ft)/0~1,160 rpm|
|Max. output||70 kW+15 kW [100 hp+20 hp)|
|Max. torque||167 Nm (123 lb-ft)|
More details will be available closer to launch.
Honda clearly intends for the new hybrid system to re-energize sales of its Civic hybrid, and to whittle away some of the marketshare currently owned by the top-selling Prius.
The Civic is Honda’s best-selling model after the Accord, with some 600,000 units sold per year.
Honda video overview of new hybrid system
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