Nissan Leaf teardown (Part 2): main components disassembled
Lithium-ion battery pack, inverter and DC-DC junction box
The Nissan Leaf EV was torn down in a benchmarking session organized by the Next-generation Automobile Support Center of the Saitama Industrial Development Corporation in December 2011 and the event was reported by MarkLines in February 2012.
The earlier report: Nissan Leaf teardown (Part 1) (posted in February 2012)
A new teardown event was recently conducted with the main units and components of the Nissan Leaf by the members of the automotive parts industries group of the Saitama Industrial Development Corporation. The result was exhibited for the public from July 17 to August 24 at the Saitama Industrial Technology Center located in the city of Kawaguchi. Among the components, the drive unit was disassembled into the motor stator, rotor, and power transmission device (reducer). Lithium-ion battery pack, inverter, DC-DC junction box, and the onboard charger were exhibited uncovered.
This report "Nissan Leaf teardown (part 2)" contains the main components that were disassembled and exhibited for public, with the addition of the brake system and the systems for cooling high-voltage parts and for air conditioning.
* Click the photo for a larger view.
Electric powertrain from the motor and power transmission device (reducer) to the driveshaft
|Power transmission device (reducer)||Actuator for electric parking brake|
|The shaft running through the rotor of the motor connects to the shaft connector shown to the right. The driveshaft connects to the shaft connector shown to the left. The power transmission device (reducer), inner view not shown, consists of the input gear shaft, main gear shaft that changes the direction of rotation as well, and the final gear. Final reduction ratio is 7.9377. The final gear that serves as the output shaft contains the differential. Supplied by Aichi Machine Industry.||The parking lock mechanism, located inside the reducer, is activated by the shift actuator (supplied by Denso) fitted to the top of the reducer. Its ECU (supplied by Advics) is located in the rear cargo room.|
Inverter and DC-DC junction box
The inverter changes direct current (DC) from the lithium-ion battery to alternating current (AC). The inverter, used in combination with the AC synchronous motor, is capable of detailed motor speed control and is a key component that supports the EV.
The DC-DC junction box that contains the DC-DC converter is located between the lithium-ion battery and the inverter. It distributes high-voltage source from the lithium-ion battery to electric devices as needed. It also converts it to 12V which is used to charge the 12V battery.
|DC-DC junction box||Larger view of the DC-DC junction box|
|The DC-DC junction box is located between the lithium-ion battery pack under the cabin floor and the inverter. Shown sideways in the photo but is actually fitted with the left side pointing upward. The DC-DC junction box serves three functions: (1) distribute high-voltage source from the lithium-ion battery, (2) supply source to the 12V electric systems, and (3) charge the 12V battery. The box, shown to the left, is the DC-DC converter (supplied by Denso) and the relays are seen to the right. The boxes labeled "Panasonic" are the general-purpose EV relay "AEV 14012 M03" supplied by Panasonic Industrial Device Obihiro. The maximum permissible contact rating of the relay that supplies source to 12V systems is 120A with the coil voltage rating of 12V DC. The junction box also contains slow charging relay and quick charging relay. The charging circuits are switched over according to the charge mode.|
|Service disconnect switch|
|Located at the center of the battery pack. In an emergency, the switch may be pulled out by hand to disconnect power. The switch can also be operated from inside the cabin.|
Charging connectors and onboard charger
|Cover of the onboard charger|
|Nichicon's product identification is shown with a warning label.|
Electrically-controlled brake system and power backup unit
|Electrically-controlled brake unit||ECU for electrically-controlled brake unit|
|The system uses the regenerative brake in coordination with the friction brake to create a natural braking feel. More than 80% of braking operation on city roads can be performed by the regenerative brake alone (without the help of the friction brake). The unit is located in the motor room and directly in front of the driver's seat. The white box at the top contains the control ECU. The round case contains the motor, and the master cylinder is seen in front of the motor (mechanical and electrical components integrated in a single unit). In designing the Leaf, the negative pressure booster in the internal combustion engine vehicle was replaced by a mechanism that converts the motor's rotation into direct action. Otherwise, the brake system from the gasoline-powered vehicle is used in the Leaf without major changes to maintain original reliability. The VDC (Vehicle dynamics control) is also taken from the gasoline-powered vehicle. Supplied by Hitachi Automotive Systems.|
|Pump to generate brake pressure|
|Located in the engine room at the right (in front of the front passenger's seat) as viewed from the vehicle front. The pump is connected to the electrically-controlled brake unit.|
|Backup unit to supply auxiliary power for brake||Backup unit for brake and Electric parking brake control unit|
|In the event of the 12V battery voltage drop, the backup unit supplies auxiliary power to the electric brake. The backup unit and the associated capacitor are supplied by Panasonic. The cover is shown to the left and the unit is shown uncovered to the right. The unit is located in the rear cargo room.||Larger view of the backup unit. The case at the upper right contains the electric parking brake control unit supplied by Advics. It is located next to the backup unit in the rear cargo room.|
|Front wheel and main brake system||Rear wheel and main brake system|
|The brake is of the ventilated disc type and the suspension is of the independent strut type.||The brake is of the ventilated disc type and the suspension is of the torsion beam type.|
Systems for cooling high-voltage parts and for air conditioning
The Nissan Leaf EV uses high-voltage current. It has separate systems for air conditioning (cooling and heating) and for cooling the high-voltage parts.
|Electric compressor for cooling||PTC heater|
|A scroll type electric compressor. It integrates the inverter, the compressor and the motor to allow the compressor operation at any speed. Supplied by Panasonic.||The PTC element generates heat when current is applied and the Leaf uses PTC heater for heating the cabin. It uses a device similar to an electric water heater and uses the hot water for heating. Supplied by Eberspaecher in Germany.|
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