Honda beginning sales of Legend with 3-motor Sport Hybrid SH-AWD system in January; V6 with cylinder deactivation

10 November 2014

Honda Motor Co., Ltd. will begin sales of the all-new Legend flagship sedan (its cousin is already on sale in the US as the Acura RLX Sport Hybrid SH-AWD) at dealerships across Japan on 22 January 2015. The fifth-generation Legend features the 3-motor Sport Hybrid Super Handling All-Wheel Drive (SH-AWD) system also offered in the RLX Sport Hybrid SH-AWD (earlier post).

Positioned at the front of the vehicle is a newly developed V6 3.5L direct injection i-VTEC engine and a 7-speed dual-clutch transmission (DCT) with an integrated 35 kW electric motor. The rear-mounted TMU (Twin Motor Unit) contains two 27-kilowatt motors that dynamically distribute electric-motor torque to the rear wheels. Both the front and rear motors capture kinetic energy during vehicle deceleration and braking and convert it to electricity to supply the Intelligent Power Unit’s 72-cell, 1.3-kWh lithium-ion battery pack, located behind the rear seatback. Teaming up with a high-output lithium-ion battery, the control unit coordinates the operation of the engine and three motors.

<!——>

The front motor is integrated with the 7-speed DCT and is connected to the driveshaft via a clutch. The motor accomplishes three tasks: (1) It supplements the V-6 engine in driving the front wheels when additional power is required, such as in a passing situation; (2) provides regenerative braking to the front wheels; (3) converts engine power to electricity to supplement regenerative braking in recharging the lithium-ion batteries.

The Power Drive Unit, packaged in the center of the vehicle beneath the center console, dictates the power management strategy of the Sport Hybrid SH-AWD system, including motor power and battery recharge.

The Twin Motor Unit (TMU) is located in between the rear wheels, where a differential on an all-wheel-drive vehicle is typically mounted. Inside its die-cast aluminum housing are two electric motors positioned back-to-back. Each 27 kW motor powers a single rear wheel. A clutch allows each motor to be decoupled from its wheel in certain operating situations to improve efficiency. Each rear motor is independently controlled and can supply advanced torque vectoring—either positive (drive) torque or negative (declaration) torque to its wheel.

Full TMU. Click to enlarge.
 
TMU motor structure (left side). Click to enlarge.

Sport Hybrid SH-AWD features three distinct driving modes, in which the hybrid system automatically controls the engine and three motors for optimal performance.

• In EV Drive, the two rear electric motors power the vehicle.

• In Hybrid Drive, the gasoline engine powers the front wheels while the two rear motors power the rear wheels.

• In Engine Drive, the gasoline engine provides power to the front wheels. Responding continuously to driver inputs and driving conditions, the hybrid system automatically selects the most energy-efficient driving mode and the optimal choice of front-wheel drive, rear-wheel drive or all-wheel drive.

In all three driving modes, the hybrid system uses all four wheels to efficiently regenerate electricity during deceleration, helping to delivery fuel economy of 16.8 km/L (40 mpg US, 5.95 l/100 km) as measured in the JC08 cycle. (As a comparison, the EPA-rated fuel economy numbers for the RLX Sport Hybrid SH-AWD are 28/32/30 mpg US city/highway/combined.)

In combination, the newly developed V6 3.5 L direct injection i-VTEC engine and three electric motors deliver maximum output of 281 kW (377 hp, 382 PS) and acceleration performance superior to that of a standalone V8 gasoline engine. Honda’s own VCM (Variable Cylinder Management) allows the engine to idle three cylinders on one side of the “V” to save energy as needed, while the hybrid system also features highly efficient regenerative braking and deceleration. As a result, the hybrid system offers fuel economy equivalent to that of a standalone inline 4-cylinder gasoline engine.

Chassis. The new Legend features Agile Handling Assist (AHA), which controls braking to enhance the vehicle’s handling performance. Also included is Vehicle Stability Assist (VSA), which is designed to assist the driver in maintaining control in challenging situations by applying braking inputs as required. Coordinated control of these technologies helps the all-new Legend deliver outstanding handling stability and performance in a wide range of driving conditions.

Further supporting the vehicle’s performance are the new lower double-joint double wishbone front suspension and multi-link rear suspension. Both the front and rear suspension feature new amplitude-sensitive dampers with an optimized spring rate and damping force, contributing to the all-new Legend’s handling stability and refined ride comfort.

The all-new Legend also features greatly enhanced body rigidity, including joint rigidity. Due to Honda’s proprietary technology for connecting steel and aluminum (earlier post), all of the door skins are made of lightweight aluminum. Lightweight construction throughout the vehicle further contributes to the all-new Legend’s outstanding handling stability and fuel economy.

Honda Sensing. The Legend also features Honda’s new advanced driver assistance system called Sensing. (Earlier post.) Designed to help the driver prevent or effectively respond to dangerous driving situations, Honda SENSING includes the first Pedestrian Collision Mitigation Steering System, which is designed to help prevent collisions with pedestrians.

The Honda Sensing system receives information from two sources with different characteristics: a millimeter-wave radar system located inside the front grille and a monocular camera mounted inside the windshield. Offering enhanced performance, the millimeter-wave radar can sense the position and velocity of a wider range of targets, including pedestrians, which tend to be difficult to sense due to low radar reflectivity. The monocular camera is able to see up to 60 meters (197 feet) in front of the vehicle, allowing the system to determine the size and other characteristics of pedestrians or objects and further enhancing the precision of the system as a whole.

In addition to these and other driver-assistive functions that sense in the forward direction, Honda SENSING includes functions that sense in the rearward and lateral directions to take safety support to the next level. Honda SENSING automatically and continuously senses the intentions of the driver and situation of the vehicle; uses visual, aural and tactile warnings to provide the driver with information and alert him or her of hazards; and provides accelerator, brake and steering inputs as needed to make the driving experience safer and more enjoyable.

Pricing for the new Legend starts at ¥6,800,000 (US$59,000); Honda is targeting sales in Japan of 300 units per month.