Nissan Leaf teardown (Part 3): body cutaway

Reducer, inverter, electrically-controlled brake and HVAC systems are highlighted

2012/11/19

Summary

 One of the main events of the Saitama Institute of Automotive Technology's campus festival, held October 27-28, was the display of the Nissan Leaf's cutaway model by the engineering students (the vehicle itself is owned by the Saitama Automotive Industry Support Center and was offered to the Institute for the occasion). The display presented more details about the Leaf's key components than we were able to get from its disassembly earlier as described in MarkLines report posted in September.

 The latest disassembly is reported below as Nissan Leaf Teardown (Part 3): body cutaway. It includes photos of components as incorporated in the cutaway model and those that have been removed and disassembled.

 The red paint identifies the separation (cut) line and the blue identifies water storage or channel.

Earlier reports:  Nissan Leaf Teardown (Part 2): Main components disassembled (posted in September 2012)
Nissan Leaf Teardown (Part 1) (posted in March 2012)


* Click on the photo for a larger image.



Overview of the Leaf's cutaway model

Overview of the Leaf's cutaway model and the front frame

Overview of the Leaf's cutaway model Inside the motor room
Overview of the cutaway Leaf Inside the motor room
 The left side of the Leaf has been cut away. Main components are left intact for the ease of understanding.  The DC-DC junction box to the right of the sturdy frame at the center of the photo; inverter surrounded by the frame; electric compressor for cooling underneath; drive motor and power transmission device (reducer) further down, and the charging connectors shown to the far left. The PTC element heater is explained later in detail.
Inside the instrument panel Front frame
Inside the instrument panel Front frame
 An expanded view of the inside of the instrument panel to the far right of the upper right photo. Air conditioning ducts are laid out inside the panel.  Front frame disassembled with the vehicle's front shown in the foreground. The silver component at the center back is the electric power steering with the stabilizer shown behind. The silver component at the center (motor cover) was there for no reasons at the time the photo was taken.

 

 



Power transmission device (reducer)

Power transmission device (reducer) and electric parking lock actuator

Power transmission device (reducer) parts (1) Power transmission device (reducer) parts (2)
Power transmission device (reducer) parts (1) Power transmission device (reducer) parts (2)
 Three gears are separated from the reducer. The final gear at the center, the main gear front right, and the input gear front left. The gear with box-shaped projections that connect to the input gear is the parking gear used for locked parking. The motor and the reducer housings are shown in the back.  The three gears are laid out as originally arranged in the reducer with the final gear, main gear and input gear integrating parking gear shown from right to left.
Differential gear
Differential gear
 The final gear as viewed from the opposite side with the differential gear assembled.
Drive motor and reducer as viewed
from the vehicle's front end
Electric parking lock actuator
Drive motor and reducer as viewed from the vehicle's front end Electric parking lock actuator
 The drive motor, left, and the reducer, right. The input gear that transmits the motor revolution and the parking gear are also seen. The upright component in the foreground of the reducer is the manual shaft of the electric parking brake. The parking brake is used to lock the reducer in position and corresponds to "P" range on automatic transmissions.  The lock actuator, right, disassembled from the electric parking brake, is normally positioned over the reducer. The manual shaft at the left (connects to the center of the actuator when assembled) is rotated until the parking gear is locked in position.
Shifters in the center console Reducer final gear and driveshaft
Shifters in the center console Reducer final gear and driveshaft
 The shifter, left, integrated in the center console is used to operate the electric parking brake. The "P" control, right, is used to operate the parking brake fitted to the back of the vehicle (more detail later). The driver's seat is seen in the back.  Viewed from the left side of the vehicle. The driveshaft projects from the final gear of the reducer to drive the wheels. The steering system is seen to the right of the driveshaft, and the stabilizer to the farther right.

 

 



Inverter and DC-DC junction box

Inverter (remaining in the cutaway model) Inverter (removed)
Inverter (remaining in the cutaway body) Inverter (removed)
 The inverter as integrated in the cutaway model, left, and removed and disassembled, right, has two circuit boards. The upper board is the motor controller, and the other the gate driver. The smoothing condenser in the background of the boards is seen in the right photo with two square terminals to the right and one to the left (six terminals in total including those hidden in the photo). The IGBT (Insulated Gate Bipolar Transistor), the key component of the motor control, is seen under the slit cut in the left of the gate driver board.
DC-DC junction box DC-DC converter
DC-DC junction box DC-DC converter
 The DC-DC converter is shown on top of the relays. They are collectively called the DC-DC junction box.  An expanded view of the DC-DC converter.

 

 



Lithium-ion battery pack

Lithium-ion battery pack Lithium-ion battery module (1)
Lithium-ion battery pack Lithium-ion battery module (1)
 Battery pack, shown as integrated in the cutaway model, is normally stowed under the cabin floor and contains 48 battery modules in an aluminum case. The modules are connected in series.  The top of the aluminum case is cut out to reveal the four modules and they are placed back in the battery pack.
Lithium-ion battery module (2) Service plug
Lithium-ion battery module (2) Service plug
 One of the modules is shown removed from the aluminum case. Each module consists of four laminated cells. The cells are connected in parallel in pairs and then connected in series to other pairs. Further disassembly of the lithium-ion batteries was not performed for safety considerations.  Located at the center of the battery pack and operated from inside the cabin. The plug may be pulled out by hand to disconnect power prior to inspection, repair, etc.
Battery controller (1) Battery controller (2)
Battery controller (1) Battery controller (2)
 The central device of battery control detects the battery voltage and current, pack temperature and cell voltages, and regulates them accordingly. The controller is located in the foreground and to the right of the battery pack in the cutaway model.  The entire board is removed from inside the battery controller.

 

 



Electrically-controlled brake system

 The system fully uses the regenerative brake in coordination with the friction brake, while creating a natural braking feel. The system is located in the motor room and directly in front of the driver's seat.

Electrically-controlled brake unit

Electrically-controlled brake unit
(viewed from the vehicle front)
Electrically-controlled brake unit
(viewed from a side)
Electrically-controlled brake unit (viewed from the vehicle front) Electrically-controlled brake unit (viewed from a side)
 A front view. The board at the top is the control ECU and the booster motor (in a round shape) is seen underneath with the master cylinder in the foreground. The wiper and the wiper motor are seen over the brake unit.  Viewed from the vehicle's left side. The control ECU is seen at the top with the booster motor in the center. The vertically-placed board at the left is the DC-DC converter.
Electrically-controlled brake components Electrically-controlled brake components (enlarged)
Electrically-controlled brake components Electrically-controlled brake components (enlarged)
 The round-shaped component is the motor. The elongated component at the center is the input rod and primary piston that connect to the brake pedal to the left (not shown). The motor is located where pointed by the red arrow (photo in the left side) and supports the input from the brake pedal. The photo also shows the spring that generates reactive force in the pedal.
 When the regenerative braking is active, the primary piston is pushed back to the pedal to reduce the master cylinder pressure and match the regenerative braking. The system is designed carefully to prevent awkward pedal feel.
Electric parking brake
Electric parking brake actuator Brake power backup unit and onboard charger
Electric parking brake actuator Brake power backup unit and onboard charger
 The electric parking brake actuator is fitted to the chassis in the back of the vehicle. The inner drum type parking brake works inside the rear wheel drum.
 It belongs to a separate system independent of the parking brake that locks the reduction gear in the reducer.
 The brake power backup unit, right, functions as an auxiliary power unit of the electric brake and supplies necessary electric power in the event of voltage drop in the 12V battery. The round-shaped components are the capacitors. The square case in front of the capacitors is the control unit of the electric parking brake actuator.
 The onboard charger is seen to the left. The backup unit and the onboard charger are located in a space between the rear seat and the rear cargo room.

 

 



Systems for cooling high-voltage parts and for air conditioning

 The Nissan Leaf EV uses high-voltage current and has a separate system for cooling the high-voltage parts in addition to the air conditioning systems (cooling and heating systems). The following components are described in this report:
* Radiator and cooling fan → High-voltage parts cooling system
* Condensers, electric compressor and scrolls → A/C cooling system
* PTC element heater, electric water pump → A/C heating system
Electric pumps are also used in the high-voltage parts cooling system and the A/C cooling system other than the A/C heating system.

High-voltage parts cooling system and A/C cooling system

Cooling fan for the radiator Radiator, cooling fan and condenser
Cooling fan for the radiator Radiator, cooling fan and condenser
 The radiator and the associated cooling fan are integral part of the high-voltage parts cooling system. Supplied by Calsonic Kansei (manufactured in Japan).  The cooling fan is seen at the top, over the radiator and over the condenser. The three parts are fitted as a set inside the front grille. The condenser is supplied by Calsonic Kansei (manufactured in China).
Cooling system
Electric compressor Electric compressor scrolls
Electric compressor Electric compressor scrolls
 Viewed from the vehicle front. The electric compressor is located over the drive motor under the inverter in the motor room. The motor is seen to the right and the scrolls to the left of the compressor.  The fixed scroll, left, and the movable scroll, right, are set facing each other in such a way to allow the movable scroll to revolve inside the compressor (it does not rotate itself). The resulting change in the volume and pressure in the space between the two scrolls is used to suck in the refrigerant from the suction port and discharge it from the delivery port.
Heating system
PTC element heater and electric water pump PTC elements
PTC element heater and electric water pump PTC elements
 PTC element heater, center slightly to the right, and the electric water pump, left, are located in the motor room. The water in the blue area of the PTC element heater is heated by the PTC element located underneath, and forced into the cabin by the electric water pump.  The parts colored blue and light brown are waterproof rubbers, and the metal-like parts seen between them are the PTC elements. These parts are located under the water storing section (colored blue) in the photo shown to the left.
Electric water pump
Electric water pump
 A disassembled view of the electric water pump. The small motor rotates to send heated water to the cabin.

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