Standard Powertrain

The Infiniti Q50 sedan features the advanced VQ37VHR, tuned 3.7-liter 24-valve DOHC V6 engine with Variable Valve Event and Lift (VVEL^®) intake camshafts. This engine incorporates the Continuously Variable Valve Timing Control System (CVTCS) technology that optimizes opening of intake and exhaust valves to help improve performance. In addition, the ECU with the VVEL^® technology enhances acceleration by optimizing the air-fuel mixture to increase fuel efficiency and reduce exhaust emissions. To obtain a natural acceleration feel, the torque curve from low revs to the maximum torque point (5,200 RPM) is tuned for linearity.

7-speed Automatic Transmission with Manual Shift Mode

The formidable VQ engine is matched to the RE7R01A electronically controlled 7-speed automatic transmission with Adaptive Shift Control (ASC). This transmission has also been equipped with predictive down-shift and gear hold functions for NAVI-equipped vehicles. Power can be driven to the rear wheels via the quick-shift Drive Sport (DS) mode or with the available solid magnesium paddle shifters affixed to the steering column. The RE7R01A incorporates driver-adaptive learning and algorithms that sense driving style and then adjusts automatic shifting accordingly.

When driving on an up or down slope, the Adaptive Shift Control (ASC) will judge the slope according to engine torque data transmitted from the Hybrid Powertrain Control Module (HPCM) and the vehicle’s speed. It then fixes at the 4GR, 5GR or 6GR position on the up-slope to prevent gear hunting, which helps the vehicle to gain optimum gear/ratio driving speed.. When driving on a curve, the TCM receives the side G sensor signal from the ABS actuator and electric unit (control unit). It then locks to the 4GR, 5GR or 6GR position in moderate cornering or to the 3GR position in sharp cornering based on this signal. This prevents any upshift and kick down during cornering operation, helping to maintain smooth vehicle travel.

Hybrid Powertrain

The Q50 Hybrid model, which is based on the M HEV sedan, is capable of delivering V8 performance with 4-cylinder fuel economy from the VQ35 3.5-liter V6 engine and a 67 horsepower traction motor/generator.

The “Infiniti Direct Response Hybrid” is a one-motor, two-clutch parallel hybrid system that combines the functions of propulsion and generation. Power output for the V6 is 302 horsepower and 258 pounds-feet of torque. It also utilizes a 346 volt motor rated at 67 hp (50kW) and 214 lbs.-ft. of torque, bringing the hybrid system net power to 360 horsepower. Whether powered by the engine, electric motor or both, the energy is directed to the rear wheels and controlled by the RE7R01H 7-speed transmission. The combination of a parallel hybrid system in which the engine power is transmitted directly with a power assist from a high-power Li-ion battery improves acceleration performance.

The single electric motor works with a two-clutch system without a torque converter. Clutch 1 (CL1) is a dry clutch that is positioned between the engine and the Traction Motor/Generator which is in-line with the front of the transmission. Installed between the engine and the motor, it engages and disengages the engine from the driveline. This eliminates the need for a torque converter and allows the full decoupling of the V6 when running in electric mode. The installation of a clutch between the engine and traction motor delivers a large improvement in fuel economy because the engine can be completely disengaged during traction motor driving. This allows all motor power to be converted into driving force whenever needed. It also helps to eliminate mechanical drag from engine friction and boost the efficiency of the electric motor by reducing engine load. Clutch 2 (CL2) is a wet/multiplate clutch located at the rear portion of the transmission and is used to transfer the power from the traction motor and V6 engine to the driveshaft. As the V6 engine is turned ON and OFF, clutch 2 slips as needed to control a smooth transfer of power during shifts and also when the V6 is engaged. The result is a configuration where all components act on a single prop shaft to the rear differential. This provides a consistent driving feel, optimizing energy usage across the widest possible range of driving conditions with linear performance and the “direct responses” that the hybrid system was named for. The Q50’s Traction Motor/Generator design is lighter than the previous designs as a result of utilizing fewer system components for providing advanced hybrid control. The traction motor inverter is composed of the motor controller, driver, smoothing condenser, current sensors, coolant temperature sensor and power module.

Traction Motor/Generator

The traction motor works during idle, stop-and-go driving and steady cruising up to 62 MPH and engages during as much as 50 percent of driving time. To provide the most effective use of the electric motor without having to use engine power, the gasoline engine will turn off completely while coasting at speeds up to 80 MPH.

During deceleration, the traction motor inverter drives the traction motor to function as a generator based on the signal sent via the HEV system CAN from the HPCM. It converts the torque generated by rotation of the tires into electrical energy. This converted electrical energy charges the Li-ion battery.

Clutch Function

Clutch 1

• Clutch 1 (CL1) is located between the engine and the front of the Traction Motor/Generator.
• When the engine is running and engine output torque is transmitted to the transmission, clutch 1 is engaged.
• During EV driving, clutch 1 is disengaged from the driveline in order to reduce the load on the traction motor.

Clutch 1 is used for starting the internal combustion engine, idle charging , and power transmission.

Clutch 2

• Clutch 2 (CL2) is a component inside the transmission that consists of the Reverse Brake and Low Brake. It is used for starting the engine, starting from a stop and shifting speeds.
• After starting the engine or during starting from a stop and changing speeds, clutch 2 is allowed to slip, which controls the drive force that is transmitted to the drive wheels, providing smooth driving and shifting.

Clutch 2 is used for launching the vehicle and providing a no drive/neutral condition for idle charging.

Sub Electric Oil Pump System

A sub electric oil pump system is used to enable the hydraulic pressure of transmission fluid through the transmission components when the combustion engine is OFF. The sub electric oil pump is necessary for the control of clutch 1 and clutch 2 during various hybrid operating conditions. The sub electric oil pump inverter applies AC power to the sub electric oil pump through the power module composed of 6 semiconductor Field Effect Transistors (FET). The FET converts DC from the 12V battery to AC electric power and is capable of switching ON and OFF at high speed. When the input speed of the transmission is low, so is the speed of the mechanical oil pump in the transmission. Therefore, the sub electric oil pump system is used to supply hydraulic pressure for the transmission to operate clutch 1. At an idling stop, the sub electric oil pump system supplies hydraulic pressure for the engagement of clutch 2.

The sub electric oil pump system consists of:

• Sub electric oil pump - 3-phase, brushless, synchronous motor
• Control modules (TCM and other modules over the HEV CAN system)
• Sub electric oil pump relay
• Sub electric oil pump inverter - the sub electric oil pump inverter is composed of the controller, driver, power module, current sensors and electronic substrate temperature sensor.

When AC electric power (3-phase AC) is supplied to a coil of the stator core, a magnetic field is generated at each U-phase, V-phase and W-phase. The direction of current (north pole and south pole) changes when FET performs switching of magnetic field, and then the magnetic field rotates. This is called rotating magnetic field. The permanent magnet in rotor core is pulled or repelled by the rotating magnetic field. Then it synchronizes with the rotating magnetic field, rotates and generates torque force.

Battery Power - Lithium-Ion

At the heart of the Infiniti Q50 Hybrid is the innovative 1.3-kWh Lithium-ion battery pack which is positioned in the trunk compartment between the rear seats and the trunk lining. The Lithium-ion battery used in the Infiniti Q50 Hybrid is lighter and more compact than traditional Nickel-Metal Hydride batteries found in other hybrids, enabling the new Q50 Hybrid to have a spacious cabin and providing more valuable trunk space. The Li-ion battery pack is laminated to enhance cooling performance and to provide exceptional battery reliability as well as fast charge/discharge response and efficiency.

The Li-ion battery pack contains a total of 96 laminated Lithium-ion battery cells. Eight cells are connected in series to form each battery module. Twelve battery modules are arranged in series to form the complete battery pack. The cumulative voltage of the battery pack is approximately 346V.

The following components are mounted to the battery assembly:

• Li-ion Battery Pack Modules
• HPCM
• Li-ion Battery Controller (LBC)
• DC/DC Converter
• Battery Junction Box
• System Relays
• Battery Cooling Fan and Ducts
• Service Plug
• Three Battery Temperature Sensors

Li-ion Battery Controller

The Li-ion Battery Controller (LBC) is installed on top of the battery pack. The LBC is the core of battery control. It constantly monitors the battery pack conditions for voltage and current, temperature inside the battery and intake temperature, and the voltage of each cell to determine the State Of Charge (SOC). The LBC helps prevent over-voltage and over-current conditions.

The LBC transmits charge/discharge power data to the HPCM to aid against battery malfunctions (over-voltage, over-discharge or over-heating) from occurring.

During cell capacity adjustment, the capacity of each cell is estimated based on the no-load voltage when the system starts, and the capacities are adjusted so that they are all at the target level. The voltage of each cell is detected inside the LBC. The battery is maintained in optimal conditions according to the cell capacity adjustment function so that a decrease in the battery charge/discharge capability, which may be caused by cell capacity fluctuation, can be prevented. The bypass switches are then turned ON to discharge the cells that have excess capacity. In this way, capacity adjustment by the Li-ion Battery Controller allows the capacity of all cells to be fully utilized.

Hybrid Powertrain Control Module

The Hybrid Powertrain Control Module (HPCM) consists of a microcomputer and input/output connectors for signal and power supply. The HPCM performs integrated control of the hybrid control system based on the various control modules and signal inputs from the sensors.

The HPCM judges the driving conditions, based on the throttle position, vehicle speed, selector lever position and other signals and calculates the target drive force for those conditions. In addition, it monitors and controls the conditions of the Li-ion battery and the system main relays and connects the high-voltage circuit. It also performs cooperative regenerative braking with the Electrically-Driven Intelligent Brake system. It performs the complete range of these various hybrid system controls, functioning as a gateway between the HEV system CAN communications and the vehicle’s CAN communication.

To control the drive force, HPCM detects the vehicle conditions based on information from the sensors and control modules, and controls the engine and traction motor. Based on the calculated target drive force and the status of each system, it distributes the required output between the engine and traction motor, and transmits the command signals to each control module.

DC/DC Converter

The DC/DC converter is installed on the Li-ion battery and contains the pre-charge relay and resistor. It reduces the high-voltage DC 346 V from the Li-ion battery to DC voltage of approximately 13 V and supplies this voltage to the onboard electrical equipment and to charge the 12 V battery.

In addition, the DC/DC converter varies the output voltage according to HPCM signals so that appropriate voltage is supplied, depending on the vehicle condition.

When high-voltage power is supplied, the HPCM activates the system main relays to supply power from the Li-ion battery to the hybrid system. The HPCM turns the system main relays (system main relays 1 and 2, and pre-charge relay) ON or OFF to connect or disconnect the hybrid system high-voltage circuit.

Battery Junction Box

The battery junction box is located near the bottom of the battery pack. The battery junction box contains the system main relays for the supply of DC electrical power from the Li-ion battery as well as the current sensor which measures the DC current. A system main relay is installed on both the positive and negative highvoltage circuits. These relays supply DC power to the high-voltage components and also supply DC power to the Li-ion battery during regeneration and charging.

System Main Relay 1

System main relay 1 is installed inside the battery junction box and is controlled by HPCM. It connects and disconnects the high-voltage circuit positive (+) side and the Li-ion battery.

System Main Relay 2

System main relay 2 is installed inside the battery junction box and is controlled by HPCM. It connects and disconnects the high-voltage circuit negative (−) side and the Li-ion battery.

Pre-Charge Relay

The pre-charge relay is contained in the DC/DC converter and is controlled by the HPCM. When a supply of high voltage power is needed, the HPCM activates the pre-charge relay, and power is supplied via the charging resistor, preventing the sudden application of high-voltage.

Service Plug Disconnect Switch

A service plug is installed on the high-voltage battery in order to securely shut off the high-voltage circuit during inspection and servicing of high-voltage components. The service plug can be accessed through the access panel inside the trunk compartment.

Battery Cooling Fan

Cooling of the Li-ion battery is performed by delivering cooled air from the passenger compartment into the trunk compartment. The air from the passenger compartment is sent through the inlet vents located in the bolster trim on both the right and left side of rear seats, to the battery cooling fan. The air is then divided between the battery module stack and DC/DC converter system while it cools the entire battery pack. The Li-ion Battery Controller receives the signals from the sensors and control unit and determines the target airflow. Based on this target airflow, the LBC changes the duty cycle of the cooling fan drive signal. The target fan speed is based on the temperature signals from the battery temperature sensors, intake temperature sensor and DC/DC converter.

The battery fan is located in the right rear quarter panel behind the trunk interior trim.

Battery Temperature Sensors

Two battery temperature sensors are installed inside the battery pack. They measure the temperature inside the battery pack and also the intake temperature. The sensors use a thermistor with a resistance value that varies according to changes in temperature. The electrical resistance of the thermistor decreases as the temperature increases and can influence battery cooling fan speed, charging rate, and system protection modes.

Clutch 1 Stroke Sensor

The Concentric Slave Cylinder (CSC) contains the clutch 1 stroke sensor that detects the status of clutch 1. When clutch 1 operates, the magnet installed on the CSC piston moves together with clutch 1, causing a change in the magnetic field of the coil inside the clutch 1 stroke sensor. The clutch 1 stroke sensor converts this change in magnetic field to a voltage signal and inputs it into the HPCM. The HPCM detects the clutch 1 status from the change in this voltage signal.

Accelerator Pedal Position Sensor

The accelerator pedal position sensor is installed on the upper section of the accelerator pedal assembly on ICC models, and is integrated with the accelerator pedal on vehicles without ICC. These sensors detect the amount the accelerator pedal is depressed.

The accelerator pedal position sensors use potentiometers to convert the amount of accelerator pedal depression to voltage signals and input the signals into the HPCM. The HPCM judges the amount and speed of accelerator pedal depression from these signals and controls the output of the engine and traction motor.

System Operation

For electric propulsion, the Q50 HEV uses a traction motor inverter. This device converts DC power from the Li-ion battery to AC power and drives the traction motor. Because the AC power frequency and voltage can be varied when the DC power is converted to AC power, the system provides a high degree of performance control.

The DC to AC inverter controls the traction motor based on the drive command signal from the HPCM over the HEV system CAN. The inverter allows the traction motor to function in two capacities; as a propulsion device and as a generator.

When the vehicle is ready, the HPCM controls the system main relay and connects the high-voltage system.

When the engine is cold and Li-ion battery level is low, in order to warm the engine or charge the Li-ion battery, clutch 1 is engaged and the traction motor output is used to start the engine.

Normal Driving

When starting and driving at low speed (motor driving), the traction motor powers the Q50 HEV. EV drive mode uses the electrical power from the Li-ion battery to drive the vehicle using traction motor output torque only.

• The HPCM transmits the engine stop command signal to the ECM, stopping the engine and disengaging clutch 1 if the vehicle speed drops to 6 MPH. It also transmits the drive command signal to the traction motor inverter, controlling the traction motor output.
• The HPCM transmits the EV indicator lamp signal to the combination meter via CAN communication. When the combination meter receives the signal, it activates the EV indicator lamp.

• When starting and driving at low speed, if clutch 1 and clutch 2 engage at the same time, the engine speed will equal the motor speed.

Low-Load Driving

During low-load driving, the vehicle is driven by engine output torque, and the traction motor generates power to charge the Li-ion battery (when the Li-ion battery level is low).

As the vehicle accelerates from low-speed driving, the engine may be required to provide adequate power. The HPCM engages clutch 1 and starts the engine, clutch 2 engages and slips to assist the traction motor in powering the vehicle without producing a rapid change in driveline torque.

Traction Motor Power Generation

The HPCM detects the Li-ion battery status from the Li-ion Battery Controller and transmits the output torque signal to the ECM to control the engine output. The traction motor inverter controls the power generation by the traction motor and charges the Li-ion battery.

Accelerating or High-Load

When the accelerator pedal is fully depressed, the engine output torque assists the output torque from the traction motor. The HPCM engages clutch 1 and clutch 2, and transmits the output torque signal to the ECM and the drive command signal to the traction motor inverter, and controls the engine and traction motor output.

Deceleration Driving

When decelerating, regenerative braking uses the motive power of the drive wheels to generate power from the traction motor and charge the Li-ion battery.

Cooperative control with the Electrically-Driven Intelligent Brake system increases the amount of power generated by regenerative braking.

Regeneration operates with the brake system in order to improve efficiency.

Hybrid System Stop

The HPCM detects the traction motor status (speed) via CAN communication from the traction motor inverter. When the ignition switch is turned OFF, and after the traction motor stops, the self shut-OFF relay turns OFF, and then the hybrid system stops. During idle-stop operation when the Li-ion battery charge is low, engine output is used to generate power from the traction motor to charge the Li-ion battery. At this time, hydraulic pressure cannot be generated by the mechanical transmission pump. Under this condition, the sub electric oil pump provides hydraulic pressure to engage and disengage the internal transmission components that control clutch 2. The HPCM engages clutch 1 and disengages clutch 2.

Infiniti Drive Mode Selector

The drive configuration of the Q50 can be rear-wheel drive or Intelligent All-Wheel Drive. Standard on the Q50 is the Infiniti Drive Mode Selector which is part of the advanced, customizable, digital environment. This system allows up to three drivers to create personalized settings for engine, transmission, handling and steering.

Five driving modes can be selected by using the drive mode selector switch (STANDARD, SPORT, ECO, SNOW and PERSONAL). The current mode is always displayed on the Vehicle Information Display. To change the mode, push the drive mode selector switch up or down and release it. The list of the drive modes appears for approximately 2 seconds on the dot matrix liquid crystal display.

STANDARD Mode is recommended for normal driving.

The SPORT Mode adjusts the steering system’s settings to provide faster steering ratios and heavier steering force.

ECO Mode adjusts engine and transmission parameters to enhance fuel economy. The ECO Mode adjusts the steering system’s settings to provide slower steering ratios and lighter steering force.

Select the ECO Mode using the drive mode selector switch. The ECO drive indicator light on the instrument panel illuminates.

When the accelerator pedal is depressed within the range of economy drive, the ECO drive indicator light illuminates in green. When the accelerator pedal is depressed above the range of economy drive, the color of the ECO drive indicator light will change to orange.

SNOW Mode is used on snowy roads or slippery areas. When the SNOW Mode is selected, engine output is controlled to avoid wheel spin. Turn the SNOW Mode off for normal driving.

When the PERSONAL Mode is selected, it allows drivers to customize dynamic functions such as:

• Engine and Transmission Settings - Characteristics such as transmission performance Standard, SPORT, ECO or SNOW along with engine performance.
• Vehicles equipped with Direct Adaptive Steering - Drivers can customize the steering response and effort from each of the following combinations.

• Active Trace Control - Active Trace Control can be set to ON (enabled) or OFF (disabled). In addition, the function level can be set to:
• Low: Small steering feedback to aid lane tracking
• High: Additional steering feedback to aid lane tracking

ECO Pedal System (if so equipped)

The ECO pedal system helps assist the driver to improve fuel economy by increasing the reaction force of the accelerator pedal. When the ECO drive indicator light is blinking or turns orange, the ECO pedal system increases the reaction force of the accelerator pedal. The ECO pedal reaction force can be adjusted to the settings: Standard, Soft or OFF.

Direct Adaptive Steering

Instead of conventional mechanical steering, the Q50 adopts a steering technology called Infiniti Direct Adaptive Steering (DAST) which is standard on all Q50 Hybrid models and available on the gasolinepowered models with the Deluxe Touring Package. This steer-bywire system was designed to control steering utilizing digital signals rather than by a mechanical connection. The Direct Adaptive Steering system changes steering angle and steering reaction force, depending on the vehicle speed, the received steering angle request signal and the steering reaction force request signal. It is capable of transmitting the driver’s steering inputs to the wheels very fast. The system has two primary benefits: It will be able to communicate road conditions into the vehicle’s system faster, and it will allow drivers to select the feel of steering they want. It allows the car to adapt to all kinds of different driving situations, and the system can be tuned by the driver for different settings. Drivers can customize the steering response and effort and it personalizes the preferences of each driver. The steering angle actuator (steering gear assembly) and the steering force actuator (steering column) are controlled by three control modules. The steering force control module, the steering angle main control module and the steering angle sub control module share the computed result of each communication signal and monitor each other. The Direct Adaptive Steering system is linked with Active Lane Control and applies a slight correction to the steering angle and the steering reaction force to help the vehicle keep a straight line when the vehicle direction is shifted by a cross wind or other forces.

The system works in parallel with the mechanical steering linkage for reliability. The system uses electric actuators rather than mechanical links, and the Direct Adaptive Steering includes a back up clutch in its column. In normal driving situations, this clutch is disengaged, but if one of the three control modules detects a fault, the clutch snaps shut and the steering acts as a conventional, electrically assisted rack-and-pinion system. The clutch can connect the mechanical steering linkage when the engine shuts off, so if the Q50 fails to start, the driver can still steer the car while pushing it.

Two assist motors mounted at 90 degrees at each end of the rack, plus a steering-force sensor, comprise the Direct Adaptive Steering’s other components. When the steering clutch disengages the rack and the steering wheel during normal operation, there is no stress/force load applied to the steering force sensor.

Steer-by-wire eliminates steering-system flex and lash, so every driver input yields a direct action at the road. When the driver selects different steering reaction speeds (quick, standard, etc.), the system selects the appropriate ratio due to steering input angle and speed along with vehicle speed and g-force/yaw rate. The ratios are variable due to driver steering reaction selection and vehicle dynamics.

Active Lane Control

The Active Lane Control (ALC) is included as part of the Lane Departure Prevention system and is controlled by the chassis control module. The system goes beyond the traditional Lane Departure Prevention system by utilizing the Direct Adaptive steering system to assist the driver in maintaining their lane of travel. Unlike Infiniti’s previous LDW system, Active Lane Control takes it a step further not only helping to prevent unintended lane drift but also by making small front tire steering input angle adjustments if the Q50 undergoes minor direction changes due to road surface imperfections. Active Lane Control was designed to help the driver maintain a straight path and reduce driver fatigue. The main benefit is its straight-tracking ability for smoother steering in certain driving situations helping drivers to use fewer steering inputs by compensating for crosswinds and road conditions like road crowns.

Active Lane Control monitors the lane markers on the traveling lane using the lane camera unit located above the inside rearview mirror. When the camera unit detects that the vehicle is beginning to move slightly away from a straight line position, the active lane control system will automatically apply a steering force torque for a short period of time using the function of the direct adaptive steering system. Active Lane Control functions when the chassis control module calculates the difference between the vehicle’s direction and the lane direction based on lane condition signal. It then transmits the steering angle request signal and steering reaction force request signal to steering angle main control module via chassis communication. In addition, it transmits the Active Lane Control system display signal to combination meter via CAN communication.

The Active Lane Control system operates under the following conditions:

• When the vehicle is driven at speeds of approximately 45 MPH (70 km/h) and above.
• When the Lane Departure Prevention (LDP) system is enabled in the settings menu on the lower display.
• When the Active Lane Control system is enabled in the settings menu on the lower display.

Dynamic Driver Assistance Switch

The Active Lane Control system is turned ON under the following conditions: Active Lane Control and Lane Departure Prevention are enabled in the settings menu on the lower display and, the dynamic driver assistance switch on the steering wheel is pressed.

The functions of the Active Lane Control system may or may not operate properly under the following conditions:

• When the VDC, EBD, or ABS systems are providing vehicle control.
• Active Lane Control will not operate at speeds below approximately 45 MPH (70 km/h).
• On roads where there are multiple parallel lane markers; lane markers that are faded or not painted clearly; yellow painted lane markers; non-standard lane markers; lane markers covered with water, dirt, snow, etc.
• On roads where discontinued lane markers are still detectable.
• On roads where there are sharp curves.
• On roads where there are sharply contrasting objects, such as shadows, snow, water, wheel ruts, seams or lines remaining after road repairs. (The Active Lane Control system could detect these items as lane markers.)
• On roads where the traveling lane merges or separates.
• When the vehicle’s traveling direction does not align with the lane marker.
• When traveling close to the vehicle in front of you, which obstructs the lane camera unit detection range.
• When rain, snow or dirt adheres to the windshield in front of the lane camera unit.
• When the headlights are not bright due to dirt on the lenses or if the aiming is not adjusted properly.
• When strong light enters the lane camera unit. (For example, sunlight directly shines on the front of the vehicle at sunrise or sunset.)
• When a sudden change in brightness occurs. (For example, when the vehicle enters or exits a tunnel or under a bridge.)
• When entering or exiting tollgates.
• When driving on roads with a widening or narrowing lane width.

Vehicle Dynamic Control (VDC)

The new advanced Vehicle Dynamic Control comes with Active Trace Control for dynamic cornering ability is standard on all models. The Vehicle Dynamic Control (VDC) system uses various sensors to monitor driver inputs and vehicle motion. Under certain driving conditions, the VDC system helps to perform the following functions:

• Controls brake pressure to reduce wheel slip on one slipping drive wheel so power is transferred to a non-slipping drive wheel on the same axle.
• Controls brake pressure and engine or motor output to reduce drive wheel slip based on vehicle speed (traction control function).
• Controls brake pressure at individual wheels and engine or motor output to help the driver maintain control of the vehicle in the following conditions:
• Understeer (vehicle tends to not follow the steered path despite increased steering input)
• Oversteer (vehicle tends to spin due to certain road or driving conditions).

Active Trace Control

Active Trace Control adjusts engine torque and individually controls brake application to each of the four wheels to help smooth vehicle response. Active Trace Control utilizes the ABS actuator and electric control unit, depending on cornering condition calculated from the driver’s steering input and multiple sensors.

Active Trace Control uses the Vehicle Dynamic Control system to individually control the application of braking to each of the four wheels. The system helps improve cornering feel by automatically applying the brakes when entering a turn so that the vehicle’s weight shifts forward to increase the load on the front wheels.

The system also helps enhance steering response in S-turns and other slalom-type steering operations. For example, if driving through an S-turn that starts with steering to the right, the right-side brakes are engaged to help turn the vehicle. When steering back to the left, the left-side brakes are engaged.

When cornering or going through an S-curve, Active Trace Control help shift weight to the front of the vehicle and applies braking to the inside wheels. This helps the driver maneuver the vehicle through the curve.

Anti-Lock Braking (ABS) with Electronic Brake Force Distribution (EBD)

The Q50’s advanced braking system automatically responds to changing conditions. ABS helps maintain control by working to prevent wheel lockup during emergency braking situations or when braking on slippery surfaces. The system detects the rotation speed at each wheel and varies the brake fluid pressure to prevent each wheel from locking and sliding. If the rear area of the vehicle is weighted with passengers, cargo or even just a full tank of gas, Electronic Brake force Distribution sends extra force to help the rear brakes to compensate. ABS and EBD are standard features.

Traction Control System (TCS)

The traction control system can sense drive wheel slip or spin and responds by helping to reduce throttle to help maintain traction. When wheel spin is detected by a wheel sensor, the engine/traction motor output and transmission shift status controls the slip rate of drive wheels at an appropriate level.

The ABS actuator and electric unit (control unit) perform brake force control of the LH and RH drive wheels by increasing brake fluid pressure and decreasing engine/traction motor torque.

Brakes

The Q50 is equipped with 4-wheel power-assisted vented disc brakes, 4-wheel Antilock Braking System (ABS), Electronic Brake force Distribution (EBD) and Brake Assist.

The Q50 is available with a Sport Brakes option that has upgraded rotors, 4-piston front calipers and 2-piston rear calipers. Larger brake rotors are used for the Sport Brakes option which results in good fade performance.

Q50 Hybrid Electronically-Driven Intelligent Brake System

The Electronically-Driven Intelligent Brake system on the Hybrid model uses both regenerative braking and conventional hydraulic braking systems, working in cooperation to increase efficiency and fuel economy. In addition, the braking system plays a major role in other advanced vehicle performance systems such as ABS, TCS, VDC, Hill Start Assist and Active Trace Control. Active Trace Control adjusts engine torque and the control of braking at each of the four wheels to help enhance cornering performance.

Three Functions of HEV Regenerative Brake System:

1. Boost Function Electrically-Assisted Actuation (e-ACT)

2. VDC Function

3. Cooperative Control Function

The advanced braking control system on the Q50 Hybrid uses an electrically-driven intelligent brake unit and supporting system components to control braking:

• Electrically-driven intelligent brake unit
• ABS actuator and electric unit (control unit)
• Brake pedal stroke sensor
• Master cylinder pressure sensor
• Brake power supply backup unit
• Traction motor inverter
• Hybrid Powertrain Control Module (HPCM)

The electrically-driven intelligent brake unit includes a control module, master cylinder and an electric brake booster to assist with braking. The intelligent brake unit controls the fluid pressure that is sent to the ABS actuator and electric unit (control unit). When the brake pedal is depressed, the pedal stroke sensor monitors the speed and force of pedal application and sends a signal to the intelligent brake unit. The brake unit generates hydraulic assist force by using the integrated electric motor within the intelligent brake unit to operate the piston in the master cylinder. The system generates fluid pressure for each brake caliper to increase, to hold or to decrease according to the signals from the control unit in the ABS actuator and electric unit (control unit).

Regenerative Braking Force Operation (Hybrid models)

Acceleration decreases the amount of stored energy in the battery. With cooperative regenerative braking, when the vehicle travels downhill or the driver decelerates, the traction motor recharges the Li-ion battery. During deceleration, the drivetrain spins the traction motor, which acts as an alternator, and converts the kinetic energy produced by the rotation of the tires into electrical energy, generating current to recharge the Li-ion battery. This electrical load slows the vehicle, creating what is known as regenerative braking. The concept of using the conventional hydraulic brake system and the traction motor for combined braking is referred to as cooperative regenerative braking.

The intelligent brake unit calculates the required braking force operation based on inputs from the pedal stroke sensor and transmits a signal to the drive motor ECU inside the DC to AC inverter. The inverter drive motor ECU sends a signal to the intelligent brake unit indicating the amount of motor regeneration force. The intelligent brake unit then adjusts the amount of hydraulic pressure required to perform cooperative regenerative braking. Several fail safe modes are incorporated into the braking system in the event of component incident.

Suspension

The Infiniti Q50 sedan is equipped with 4-wheel independent multi-link suspension (front single pivot double wishbone design/revised rear design) with extensive use of lightweight aluminum components and front and rear stabilizer bars. Sport-tuned suspension is also available.

The double-wishbone front and multi-link rear suspension gives the Infiniti Q50 exquisite ride quality on the open road, and firm, taut handling in corners. Springs, shocks and stabilizer bars are tuned for crisp performance.

The rear suspension is an independent, multi-link with coil springs over double piston shock absorbers, stabilizer and anti-roll bar. Double piston shock absorbers provide high damping force at low vibrations (flat ride) and low damping force at high frequency vibrations (smooth ride).

NAVI Synchronized Shift Control (if so equipped

NAVI Synchronized Shift Control automatically adjusts the Automatic Transmission (AT) gear position in certain situations based on road information from the navigation system.

When the navigation system detects that the vehicle is approaching a curved road, NAVI Synchronized Shift Control with predictive down-shift and gear hold functions will adjust the gear position if needed to help the driver run through the curve smoothly. The NAVI Shift Control does not provide steering input or automated driving on a curve.

The NAVI Shift Control may not operate properly in the following situations:

• If the vehicle’s transmission, engine, navigation system and/or GPS is malfunctioning.
• If the vehicle speed is higher than 74 MPH (120 km/h) or lower than 19 MPH (30 km/h) and/or the transmission gear is outside the operating range of the system.
• Fail-safe

When an error occurs in the system while NAVI shift control is ON, the NAVI shift control is turned OFF and the NAVI shift control switch on the navigation screen becomes inoperative.

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