Infiniti to Feature M35h Hybrid at Paris Show

The M35h. Click to enlarge.

Infiniti is using the biennial Paris Motor Show to showcase the M35h hybrid performance sedan, due to begin sales in Europe next spring. The M35h uses an original parallel one motor/two clutch hybrid system and features a decoupling 225 kW (302 hp) 3.5-liter V6 engine; a 50 kW, 270 N·m (199 lb-ft) electric motor integrated into the 7-speed automatic transmission (7AT); and a high-output, fast charge/discharge 1.3 kWh Li-ion battery pack. (Earlier post.)

Infiniti is calling the M35h “the driver’s hybrid” for its high power output, Infiniti Direct Response Hybrid technology and strong rear-wheel drive. With acceleration from 0-100 km/h in less than 5.9 seconds, and a top speed of 250 km/h (155 mph), the M35h has combined fuel consumption of 7.3 L/100km (32.2 mpg US) and CO2 emissions of less than 170 g/km (all figures subject to final homologation).

The architecture of Nissan/Infiniti’s new parallel one motor/two clutch system. Source: Nissan. Click to enlarge.

The M35h will be available in base and luxury GT forms, with the top GT Premium model fully equipped as standard.

The M35h can cruise on electric power alone at a constant 80 km/h (50 mph) on a level highway. Electric mode only can be utilized at speeds as high as 140 km/h (87 mph) on a trailing throttle. In slow-moving traffic, the M35h has an all-electric range of up to 2 km (1.24 miles). Infiniti says that testing has shown that, in mixed diving, the M35h is able to drive in electric-only mode for as much as 50% of the time.

The 3.5-liter gasoline V6 delivers 350 N&iddot;m (258 lb-ft) of torque at 5000 rpm. The 50 kW electric motor delivers its peak 270 N&iddot;m at just 1000 rpm, ensuring dynamic performance from standstill. Both gasoline V6 and electric motor deliver their power to the rear wheels via a 7-speed automatic transmission. An electronically controlled clutch rather than a torque converter enhances responsiveness and reduces fuel consumption over the M37 by up to 10%.

A new electric/hydraulic power steering system saves another 2%. The single electric motor and lithium ion battery pack boost efficiency further by helping keep the weight gain over the M37 down to about 120 kg. The batteries are under the trunk floor.

Infiniti Direct Response Hybrid system. Two new technologies are fundamental to the M35h’s broad-ranging abilities. One is the lithium-ion battery pack – quick to alternate between charging/discharging and, size for size, twice as powerful as conventional batteries. The second is the direct manner in which the gasoline or electric power is delivered to the rear wheels. This directness is central to the M35h’s overall efficiency as well as the reason behind the consistent driving feel under all conditions.

The first (dry) clutch is installed between the naturally-aspirated V6 and the electric motor and facilitates full decoupling of the V6 when the car is in electric drive and power regeneration modes. Decoupling the V6 reduces mechanical losses and boosts efficiency of the electric motor.

The second (wet) clutch is sited on the other side of the electric motor. It is packaged within the automatic transmission where its function replaces that of a conventional torque converter, in effect turning the 7-speed gearbox into an automated manual, with a cut in fuel consumption of up to 10% over an equivalent model with conventional torque converter automatic.

The electronically-controlled transmission also enhances responsiveness for a sportier-feeling drive; acceleration is seamless thanks to motor-assisted gear-shifting.

The 50 kW electric motor acts as both propulsion unit, either alone or in tandem with the V6 when maximum acceleration is required, and also as a power generator. As well as charging the battery in the normal way, the motor recovers energy otherwise lost during deceleration and braking.

The 225 kW gasoline engine was chosen for torque characteristics that complement the electric motor’s output, negating the need to install the 3.7-liter VVEL V6. The electric motor’s high torque from zero rpm provides strong step-off performance and contributes to the sporting feel at low speeds.

As well as its fast charge/discharge response and 1.3 kWh capacity, the lithium ion battery pack is laminated to enhance the cooling performance. Temperature stability is further improved by the use of manganese positive electrodes.

The additional weight due to the hybrid drive is kept in check in the M35h by the lightweight batteries and features such as the single electric motor, replaced torque converter and innovative steering and braking systems, in addition to a strict weight-saving regime already integral to the M Line.

Steering and Braking. The M35h is equipped with new steering and braking technologies which have been designed to deliver both environmental benefits and enhanced driving feel, reinforcing strengths already central to the car.

The steering is an electro-hydraulic system with on-demand assistance. The motor cuts in only when the wheel is turned, further boosting efficiency. The system is more compact and lighter than traditional power steering set-ups, due to the integration of multiple parts.

The brakes are similarly designed primarily to suit sports sedan buyers’ needs while at the same time contributing to the M35h’s lower carbon footprint. The engineers looked to the hybrid system itself for the solution. What they came up with – a way to use the electric drive motor to operate the brake cylinders – represents another world-first innovation for the Japanese brand.

The braking system, newly developed by Infiniti engineers, is called Electric Driven Intelligent Brake and uses the electric drive motor to operate the brake cylinders. When the driver steps on the brake pedal, the necessary braking force is maintained while the hydraulic pressure of the friction brake is controlled to help maximize the energy regeneration of the hybrid motor. Because of its simple structure, in which the motor directly operates the brake cylinders, the Electric Driven Intelligent Brake system has the potential to be a key part of all future Infiniti Direct Response Hybrid vehicles, the company said.

Prices and full specifications of the M35h will be confirmed in the new year.

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