The exceptional dynamic capabilities of the new NSX are enabled by its revolutionary Sport Hybrid Super Handling All-Wheel Drive power unit, the first such system of its kind in a supercar, utilizing electric motor torque in combination with engine power to enhance every element of dynamic performance—acceleration, handling and braking.
At the heart of this new Sport Hybrid power unit is a bespoke, mid-mounted twin-turbocharged, 75-degree, 3.5-liter DOHC V6 engine with dry sump lubrication, electric Direct Drive Motor, and an all-new 9-speed dual clutch transmission (9DCT). Together, these components comprise the rear power unit. Amplifying the instant responses and dynamic handling performance of the NSX is the front Twin Motor Unit (TMU), with two electric motors independently driving the left and right front wheels.
Sport Hybrid power unit layout
The NSX’s Sport Hybrid power unit offers exceptional horsepower and torque with a broad powerband for tremendous throttle response and acceleration. Peak total system output is 573 horsepower—500 horsepower from the gasoline engine and 73 horsepower from the front TMU and Direct Drive Motor.
By creating a vehicle propulsion system that utilizes both mechanical and hybrid-electric components rather than just a conventional gasoline-powered internal combustion engine, Acura endows the NSX power unit with constant and linear power anywhere in the powerband, at any speed, with virtually zero delay.
For example, at initial launch from a standstill, the front-mounted Twin Motor Unit (TMU) and the Direct Drive Motor immediately supplement power production from the twin-turbocharged V6 engine, using the abundant and instantaneous torque production inherent in electric motors. Conversely, once the vehicle has reached a steady state cruising speed, the twin-turbocharged V6 engine becomes the primary motive force for the vehicle, with the three electric motors providing supplementary power and/or yaw control when necessary.
While the primary focus in the development of the all-new NSX’s clean-sheet power unit was all-out performance, efficiency and environmental sustainability are also important characteristics—as with any Acura powertrain. Therefore, the all-new NSX not only boasts a best-in-class EPA combined fuel economy rating of 21 mpg (20 mpg city/22 mpg highway), but it also meets the California Air Resources Board’s ultra-low emissions vehicle (ULEV) requirements.
ENGINE
Engine at a Glance
- Longitudinally mounted, 75-degree, 3.5-liter DOHC V6
- 500 hp; 406 lb.-ft. torque
- Twin single-scroll turbochargers with electronic wastegate
- Swing arm valve actuation
- Dual Variable Valve Timing Control (VTC) for both intake and exhaust camshafts
- Dry sump lubrication system
- 10.0:1 compression ratio
- Direct and port fuel injection systems
- Drive-by-wire throttle
Twin-Turbocharged V6 Engine
Featuring a wide V-angle of 75 degrees for a low center of gravity, the NSX’s 3.5-liter twin-turbo V6 engine achieves the ideal balance between power production, overall compactness and low mass. It combines both direct and port fuel injection, along with Dual Variable Valve Timing Control (VTC) to deliver optimal camshaft phasing, allowing for precision combustion control throughout the entire rpm band while achieving high power output.
Additional key engine design elements include a sand-cast aluminum engine block, lightweight and compact aluminum cylinder heads, plasma transferred wire arc thermal spray-coated cylinder walls (for high thermal efficiency with low weight and compact size) and a dry sump lubrication system that significantly reduces the engine’s center of gravity while ensuring consistent engine lubrication under high cornering load conditions.
The NSX utilizes swing arm-type valve actuators which allows for a compact head structure and reduces the inertial weight of the valvetrain by 22 percent compared to a rocker arm-type design. The innovative design was derived from Honda racing engines. Intake and exhaust variable cam timing (VTC) is deployed to provide an excellent balance of high power, torque, fuel efficiency, and emissions.
Acura Firsts for the 2017 Acura NSX Twin-Turbocharged 3.5-liter V6 Engine:
- Use of both direct and port fuel injection systems
- Swing arm-type compact valvetrain system
- Two-stage chain drive system for the camshafts
- Twin-turbocharged and intercooled induction system
- Three-piece water jacket for the engine block and heads, including water jackets between the cylinder bores
- Plasma transferred wire arc thermal spray-coated cylinder walls
- Dry sump lubrication
- Triple radiator system
- Viscous damper mounted to the crankshaft
Turbocharging System
Developing a bespoke twin-turbo system for the all-new engine was a logical choice, offering a strong balance of high power with considerable torque, high fuel efficiency and low emissions, while also offering inherent packaging advantages. Maximum boost pressure is set at 105 kPa (1.05 bar, or 15.23 psi). High volumetric flow air-to-air intercoolers are adopted, dramatically reducing intake air temperature while simultaneously increasing the density of the air intake charge for maximum power production.
Making use of an electronic wastegate for each turbocharger for fast response and precise control, the single-scroll turbocharger design allows for the use of relatively small turbos to minimize weight and improve packaging while still meeting power and performance benchmarks.
Plasma Transferred Wire Arc Thermal Spray Coating
Utilizing an aluminum engine block and heads offered three key advantages compared to traditional cast iron block and head configurations: (1) greatly reduced mass; (2) improved thermal conductivity; and (3) improved heat dissipation. Most aluminum engines require the fitment of cast iron cylinder liners to provide sufficient wear resistance. But engineers on the NSX’s power unit development team addressed this issue by employing a plasma transferred wire arc thermal spray to the cylinder walls—a recently developed technique that offers 52 percent better heat transfer (thermal conductivity) with greatly reduced weight versus cast iron liners.
Using a thin-diameter wire as feedstock material (approximately +/-1 mm), the process melts the wire down to an atomized form that can then be sprayed onto the cylinder walls. A supersonic plasma jet formed by a transferred arc between the tip of the wire and a cathode is used to spray the molten material, stacking the tiny particles on top of each other to form a very thin yet extremely wear-resistant coating.
Along with the improved engine efficiency via reduction of internal friction, additional benefits from the thermal spray process include a nearly seven pound decrease in overall engine weight compared to iron cylinder liners, improved wear resistance and reduced oil consumption, and increased horsepower/torque production and throttle response.
Furthermore, thanks to the addition of plasma transferred wire arc thermal spray, additional water channels are able to be placed between the cylinder bores for improved cooling efficiency via better control of coolant flow.
Racing-Inspired Cylinder Head Design
Using engineering and design expertise drawn straight from the company’s extensive racing experience, the cylinder heads fitted to the twin-turbo V6 are highly compact and include smaller valvetrain components. This resulted in a notable reduction of inertial weight as well as a 22 percent reduction of cylinder head mass compared to conventional designs. The reduction in mass also helps lower the vehicle’s center of gravity.
The cylinder heads utilize a three-piece water jacket for improved cooling efficiency and coolant flow control. Additionally, the race-inspired cylinder head design optimizes the swirling of intake air so that fuel mixes with it in a more ideal manner for improved combustion—thus improving efficiency and emissions performance.
High Specific Power Output
With a compression ratio of 10.0:1 the NSX engine has a specific power output of more than 140 horsepower per liter of engine displacement. The engine safely and reliably achieves the high specific output due to a number of advanced technologies including the efficient twin-turbo system, low internal friction, heat transfer properties of the plasma transferred wire arc thermal spray on the cylinder walls, sodium-filled exhaust valves, implementation of both direct and port injection, and the superior combustibility of fuel from the high-swirl ports.
Dual Variable Valve Timing Control (VTC)
The NSX engine incorporates proprietary Dual VTC variable valve timing control technology which delivers an excellent balance of high torque and maximum power output with reduced exhaust emissions and superior fuel efficiency.
At engine idle, Dual VTC stabilizes combustion for smooth idling by minimizing intake and exhaust valve overlap, therefore decreasing the amount of exhaust gas recirculation. During steady-state cruise or under light acceleration, the system reduces exhaust emissions and engine pumping losses by optimizing valve overlap. Under wide open throttle at low engine speeds, the overlap of the intake and exhaust cam timing is expanded so that the turbochargers can work at maximum efficiency for optimal power delivery and responsiveness. Conversely, when operating the engine at elevated rpms, overlap of the exhaust and intake timing is minimized for improved volumetric efficiency to create maximum power.
Direct Port Fuel Injection
The NSX engine combines both direct and port fuel injection systems to provide outstanding power with exceptional emissions performance.
Direct injection is the primary means of fuel delivery within each cylinder, while port injection is used for additional power output in high-performance driving situations. The direct injection system’s electronic fuel injectors are mounted in the cylinder heads and spray a very fine, highly atomized mist of fuel directly into each cylinder under very high pressure so that the fuel ignites almost instantaneously and completely with ignition spark, maximizing engine performance and fuel efficiency with reduced emissions. Under high performance demands, the port injection system supplements the direct injection system, feeding fuel into the intake ports where it mixes with the incoming air for increased power production.
The direct and port injection systems are fed by two specially designed fuel pumps, one feeding the direct injection system at a fuel pressure of 65 psi, the other supplying the port injection system at 51 to 73 psi.
The NSX’s engine includes advanced lean-burn combustion technology that allows for homogenous and weak stratified combustion to occur within the cylinder due to ultra-precise control of the fuel injection. By ensuring that fuel spray angle and direction do not interfere with the intake valves, along with a strong air/fuel swirl from the high tumble port, high power output and low emissions are effectively combined. Along with optimized piston head and intake port shapes, the highly accurate fuel spray and injection pattern play pivotal roles in this advanced combustion concept.
Intake Manifold
A two-into-one intake manifold design minimizes torque deviation between each bank of cylinders. Twin throttle bodies allow more air into the system and finer throttle control while simultaneously reducing the pulsation of air.
Exhaust System
Compact and lightweight, the stainless steel exhaust system fitted to the NSX includes two catalytic converters per cylinder bank and four outlets for excellent exhaust gas flow and low emissions. Silicon exhaust system mounts resist heat and offer a robust means of securing the exhaust system to the vehicle, helping to reduce vibration while ensuring system integrity and long life.
Engine Sound Management
Intake Sound Control
To enhance the interior auditory experience, the NSX includes a new Intake Sound Control system that works cooperatively (via the Integrated Dynamics System) with the Active Exhaust Valve system (see Exhaust Sound Management below).
Intake Sound Control utilizes a pipe, connected directly to the engine’s intake manifold, with an electrically operated butterfly valve that can be opened and shut, depending on the Integrated Dynamics System setting, and a diaphragm that translates high pressure air from the manifold to lower pressure sound waves. On the other side of the diaphragm, the single pipe then splits into two pipes that transmit sound to twin outlets in rear uppermost portions of the cabin. Sound transmission and effect are varied in concert with the four driving modes of the Integrated Dynamics System (Quiet, Sport, Sport+ and Track)—with 25 decibels sound pressure level range between Quiet and Track modes—a tremendous variance in audible sensation.
Active Exhaust Valve
An Active Exhaust Valve system has been developed for the new NSX that combines quiet and refined driving and pulse-quickening excitement, operating as a complementary component of the Integrated Dynamics System. The system utilizes two distinct exhaust paths controlled by two electrically-operated valves.
- In Quiet mode, the exhaust valves are closed and the exhaust gases pass through silencers for a more subdued exhaust sound. Power and torque production from the twin turbo V6 engine is ample.
- In Sport mode, the exhaust valves are closed unless driver demand is high enough and then will open.
- In Sport+ or Track modes, the Active Exhaust Valve system is open, bypassing the silencers for a full, uninhibited flow of exhaust gases and a full-throated exhaust note.
Together with cabin sound modulation technologies—Active Sound Control and Intake Sound Control—the Active Exhaust Valve system serves to create a customizable auditory experience both within and outside of the NSX—from the hushed silence of Quiet mode to the full concerto of Track mode, when the cabin is filled with sounds every driving enthusiast loves to hear—the high-performance “pop” from the exhaust when executing an upshift; the quick blip of the throttle upon downshifting; and the occasional distinctive off-throttle burble that is a welcome reminder of the power and torque capability of the twin-turbocharged V6 engine.
Dry Sump Lubrication
In another application of race-bred technology, the all-new NSX is the first production Acura vehicle to use a dry sump engine lubrication system. By replacing the engine’s conventional oil pan with a separate oil reservoir and a dedicated chain-driven oil pump mounted directly to the lower engine block, the system is designed to prevent oil starvation under high lateral G loads.
After being fed to the engine for lubrication, oil is collected from the lower engine block by six separate scavenger pump impellers and then fed back into the oil tank by a pair of pump rotors.
Importantly, the adoption of a dry sump system allowed designers to mount the engine 2.4 inches (61 mm) lower within the chassis, significantly lowering the center of gravity thanks to the elimination of a traditional oil pan. The more efficiently cooled oil also helps promote maximum engine power output.
“Starter-less” Engine Start System
As a byproduct of its Sport Hybrid power unit, the NSX utilizes its Direct Drive Motor to start the engine, replacing a conventional 12-volt engine starter motor.
Along with a significant weight savings, further mass reduction was realized by eliminating the 12-volt starter ring gear normally required by a conventional engine starting system.
Engine Idle-Stop
To help improve fuel efficiency, the NSX comes equipped with idle stop capability. When the system is active and certain operating conditions are met, the NSX engine will automatically shut off when the vehicle comes to a stop. The system is not engaged when Sport+ or Track modes are selected. When stopped, a special cold storage evaporator in the air conditioning system helps maintain a comfortable cabin temperature even in warm weather.
Engine restarts are exceptionally smooth and quick, supported by the use of the powerful Direct Drive Motor as an engine starter (see above). Idle Stop operation is also fully integrated into the operation of the Automatic Brake Hold system.
Engine Balancing and Break-In
The NSX power unit development team further improved engine performance and refinement through reduction in experienced noise and vibration. The latest in engine balancing technology and a number of new processes are applied to achieve optimal balance. These include the use of next-generation engine diagnostic equipment to more accurately measure engine imbalance, and the application of variable weight bolts applied to the eight mounting holes in the flywheel, and the addition of nine mounting holes in the crankshaft viscous damper which can be used for fine tuning. Achieving a high degree of harmonic equilibrium not only greatly reduces engine vibration, but also decreases wear of the engine’s internal componentry for superior reliability and longevity.
As an important additional quality step prior to fitment within the NSX, the engine undergoes a “hot fire” break-in program, wherein the engine is run under load on a specially designed engine dynamometer for an equivalent of 150 miles of service.
TRANSAXLE
9-Speed Dual Clutch Transmission with Direct Drive Motor
The NSX’s bespoke 9-speed dual clutch transmission (9DCT) works in concert with the Rear Direct Drive Motor to make full use of the power unit’s broad powerband, producing quick and precise gear changes that support the instant acceleration responses. As a key component of the power unit’s packaging, the 9DCT has been optimized for compact size, low mass and low center of gravity.
The 9DCT has a very wide ratio range that allows for optimal gear selection in any driving condition. First gear ratio is configured for maximum vehicle launch acceleration, while the close-ratio gears (2nd through 8th) are matched to make the most of the power unit’s powerband. Conversely, high gear (9th) has been optimized for fuel efficiency during steady-state highway cruising. When driving in ninth gear on a level surface at 60 mph, the twin-turbo engine is spinning at only 1,700 rpm.
In efforts toward compactness, the clutches and the differential are uniquely situated side-by-side in a common housing. Also, the parallel shaft layout reduces overhang from the rear axle while the center of mass is moved forward.
Top view of the 9DCT shows the differential situated to right side of the dual-clutch system and the parallel shaft layout, both of which reduce the length of the transaxle assembly.
9-Speed Dual Clutch Transmission at a Glance
- Competition-inspired, steering wheel-mounted paddle shifters
- Close-ratio gears selected for maximum sports performance
- Coordination between Sport Hybrid All-Wheel-Drive system and gearbox makes for ultra-quick and smooth shifts
- Wide total gear ratio spread to maximize sporting performance as well as stress free and efficient steady-state highway driving
- Dual-cone synchronizers for 2nd to 5th gears
Other advanced technologies incorporated into the 9-speed DCT:
- Electronically-operated wet dual clutches, high-rigidity shift fork, double-cone synchronizer, and electronic shift actuator to precisely synchronize shift timing with power unit torque for the quickest and smoothest shifts possible
- Precision surfaced high-efficiency hypoid bevel gear tooth shape for all gears for smooth operation and minimal gear noise
- Use of two oil “rooms” within the transmission housing for efficient and high-capacity cooling
- Clutch case and differential carrier integrated into the transmission for a lighter and more compact structure
- Lightweight, high-strength gearbox case
- Multi-plate limited slip differential (LSD) helps maximize available traction when accelerating and cornering at the limits of tire adhesion
- The addition of a lightweight single mass damper for low noise and vibration levels
- The inclusion of exclusive new gear oil that ensures higher viscosity and improved lubrication throughout the gear train (versus conventional heavier gear oil that increases viscous drag)
Quick Response Gear Shift System
One of the key parameters that sets a supercar apart from competing vehicles is how quickly it can execute gear shifts. To deliver superior shifting performance, the 9DCT features unique components to deliver lightning quick yet smooth gear changes.
Highly rigid shift forks composed of a specialized high-strength cast iron play a key role in providing quick shifts. A total of five shift forks are used for the gear actuator system: a one-way clutch is used for 1st gear; four shift forks are used for the 2nd through 9th gears; and a fifth shift fork is employed for Park and Reverse.
Gear Shift Actuator
Ultra-quick shift response and engagement with reduced weight (vs. conventional pneumatic or hydraulically operated gear actuators) is made possible by the use of a compact electric motor as a gear shift actuator. Weight is reduced by eliminating the high-pressure hydraulic pump that is typically used in a gear shift actuator system, while providing for excellent reliability and system robustness.
Electric Clutch Actuator
Like the aforementioned electric motor-powered gear actuator, the electric clutch actuator eliminates the need for a high-pressure hydraulic pump. Control of the clutch is accomplished via a closed-circuit hydrostatic structure, providing oil pressure on demand with greater efficiency.
Integrated Dynamics System Modes Modify Shift Characteristics
Adding to the performance characteristics of the NSX’s advanced 9-speed DCT is the ability to modify shift speed and feel via the distinctly different transmission settings within the driving modes of the Integrated Dynamics System:
Quiet – Transmission shift map directs gear shifts at lower engine speeds
Sport – Transmission allows the engine to rev more freely and makes gear changes in a higher RPM range
Sport+ – Accommodates higher engine speed gear changes with quicker, more aggressively executed upshifts and downshifts
Track Mode – Fastest upshifting—40 milliseconds faster than Sport+ settings
Flywheel Mass Damper
To minimize powertrain vibration, the flywheel has been designed to also act as a mass damper to minimize mechanical/harmonic vibration caused by oscillation, while helping to ensure structural integrity and longevity of the transmission case.
Limited-Slip Differential
The new NSX’s remarkably crisp turning capability and tractability is further enhanced by a mechanically-based limited-slip differential (LSD).
Designed to deliver excellent poise and stability while making of the most of the power unit’s ample power production, the torque-sensitive multi-plate clutch is lighter and more compact than a similar unit with a helical gear configuration. Also, the multi-plate design allows for improved wheel coupling for smoother and more efficient operation.
The NSX’s LSD torque bias ratio—an index for slip limit torque that compares torque shifted from a high rotation axle to a low rotation axle—has been optimized to provide two distinct LSD performance settings ideal for when the wheels are being driven or when the vehicle is coasting.
Engineered to complement the Twin Motor Unit (TMU) and Vehicle Stability Assist (VSA) systems with precision torque vectoring and enhanced traction maintenance, the LSD helps advance vehicle performance in a number of driving situations:
Under Braking/Deceleration Approaching a Turn
Increases engine brake torque on the outside tire/wheel for improved vehicle stabilityStraight-line Driving
Torque is transferred left-to-right as necessary for enhanced vehicle stability when driving in a straight line.Under Acceleration while Turning
Overall vehicle tractability and poise is improved by shifting torque to the outside tire as traction from the inside tire decreases.
Rear Power Unit Mounting
By employing strategically-placed rear power unit mounting points—up high at the front of the engine along with a mounting cradle bracket down low at the rear (connected to the transmission)—roll, pitch and yaw motion of the power unit is greatly reduced, providing greater acceleration response and handling ability.
SPORT HYBRID SYSTEM
The Sport Hybrid system is a suite of highly advanced components at the center of the hybrid-based systems of the power unit. Each component is engineered to minimize both weight and size in order to reduce overall vehicle mass, and carefully packaged within the NSX to lower and center the mass within the vehicle. Collectively, the Sport Hybrid system includes the Twin Motor Unit (TMU), Direct Drive Motor, Power Drive Unit (PDU), and Intelligent Power Unit (IPU).
Twin Motor Unit (TMU)
The new NSX’s instant and linear acceleration coupled with outstanding dynamic capability is enabled in large part by its front-mounted Twin Motor Unit (TMU). Designed to be as small and lightweight as possible while delivering ample torque and power, as well as precise torque vectoring to the front wheels, the TMU is a unique and highly efficient solution to provide supplemental power to the twin-turbo V6 engine for instantaneous acceleration whenever desired.
The TMU provides instant torque as well as AWD capability, allowing direct and immediate acceleration with a heightened sense of G-loading that invigorates the senses. Further, the TMU can dynamically apportion its torque to create a yaw moment, enhancing cornering performance. Finally, the TMU recovers braking energy during deceleration to supply power to the hybrid batteries.
Inside its die-cast aluminum housing are two electric motors positioned back-to-back. Each 36 horsepower motor powers a single front wheel and can also apply negative torque to the same wheel. A gear mechanism allows the motors to decouple and still provide on-demand torque vectoring, helping to improve efficiency in certain conditions.
To achieve maximum acceleration from a standstill and to meet the NSX engineering and design team’s target of instant response, the TMU and Direct Drive Motor provides the bulk of the accelerative force during initial acceleration from a standstill. After the first 0.15 seconds/0.1 G off of the line, the high horsepower and torque from the twin-turbocharged V6 engine enters the fray, along with still more power from the Direct Drive Motor. From there, the engine exponentially increases its power contribution as the vehicle continues accelerating.
The TMU is also a key motive force for driving in the Quiet mode setting of the Integrated Dynamics System, allowing for hushed vehicle operation by powering the NSX electrically for short distances.
TMU Highlights:
- Provides true (positive and negative) torque vectoring at any vehicle speed to enhance NSX dynamic excellence
- Compact mechanism with high power/torque output for its weight and small size
- Motive vehicle force and power regeneration are performed by both motors, with right-and-left operational independence
- Realizes high levels of right-and-left torque distribution to the front wheels while consuming a small amount of electric energy
- A motor disconnect mechanism provides motor overspeed protection as well as a reduction in energy losses
- Uses a double pinion planetary deceleration mechanism, a separation mechanism and an oil pressure control system
Direct Drive Motor
The Direct Drive Motor, mounted between the engine and transmission, is ideally packaged to provide additional torque and power assist to the rear wheels in the most efficient manner.
The Direct Drive Motor is shown mounted to the rear of the twin-turbo V6 engine.
To help eliminate the response delay typically associated with turbocharged engines, the Direct Drive Motor (shown at left) acts directly on the engine’s crankshaft which, together with the TMU, help the NSX realize immediate, high-output, high-torque acceleration performance. The effectiveness of this design is particularly noticeable in everyday driving when accelerating from a standstill and at low engine speeds. Additionally, the Direct Drive Motor acts as a generator to help charge the hybrid batteries, while also acting as the engine starter.
The Direct Drive Motor is liquid cooled to ensure ample cooling and heat dissipation even when the system is being worked hard, such as on a track day.
Intelligent Power Unit (IPU)
Neatly packaged in the cabin, just forward of the rear bulkhead, the Intelligent Power Unit (IPU) acts as the primary heart and brains of the E-Drive system, integrating the lithium-ion battery pack, junction board, a high-voltage distribution bus bar, 12-volt DC-DC converter, electric motor ECU, lithium-ion battery ECU and the ECU for the TMU.
Thanks to the integration of a next-generation lithium-ion battery pack and a caseless structure for key Intelligent Power Unit (IPU) components, the NSX’s IPU system is 35 percent smaller and 30 percent lighter than the IPU in the Acura RLX Sport Hybrid sedan.
When driving in Sport, Sport+ and Track modes, the vehicle’s air conditioning system is used for supplemental cooling of the IPU for optimal efficiency and performance. During development, the system was tested extensively in the desert heat of Dubai in order to ensure proper function in extreme ambient temperatures.
Lithium-ion Battery Pack
Packaged within the IPU is the lithium-ion battery pack which stores the electrical energy to power the TMU and Direct Drive Motor.
The high-output battery pack consists of four modules, each with 18 individual battery cells (72 cells in total) contained within a specially designed caseless structure that utilizes the vehicle body itself for a lightweight yet sturdy housing. Compared to the latest Acura RLX hybrid, the NSX battery pack’s power density (stored energy per kilogram) has been increased 10 percent while energy density is up 15 percent.
Power output and efficiency of operation have been further improved by implementing a cooperative battery cooling system, fed by fresh cool air channeled into the passenger compartment via the vehicle’s air conditioning. Cool air from within the cabin circulates through ducting to cool both the lithium-ion batteries as well as the DC/DC converter.
Power Drive Unit
The Power Drive Unit (PDU) dictates the power management strategy of the Sport Hybrid SH-AWD system, including motor power and battery recharge. The PDU also incorporates three separate converters (converting direct current to alternating current) for use by the power unit’s three electric motors: the twin motors of the front-mounted TMU and the Direct Drive Motor. This compact “three-into-one” PDU design is critical to the system’s compact packaging and the ability to mount it centrally in the vehicle, in the center tunnel (beneath the center console).