Honda Fit Hybrid teardown (Part 2): Engine and transmission

Engine & 7-speed dual clutch transmission with built-in motor is shown

2013/12/20

Summary

A cutaway model of the 7-speed DCT
A cutaway model of the 7-speed DCT exhibited at the "new technology presentation" held by Schaeffler Japan in October 2013.
* Click on the photo for a larger image.

 Disassembly event of the Honda Fit Hybrid was organized by Saitama Industrial Development Corporation, Next Generation Automobile Industry on November 2013. Disassembly of the battery-related components and the electric servo brake system was reported already in:


Previous report:
Honda Fit Hybrid teardown (Part 1) (Dec. 2013)


 This report, Honda Fit Hybrid Teardown (Part 2), mainly covers the function of the drive unit that comprises the engine, the motor and the 7-speed dual clutch transmission (DCT).


Related Reports: Toyota Aqua (Prius c) teardown: Part 1 (Nov. 2012)
Toyota Aqua (Prius c) teardown: Part 2 (Nov. 2012)
Nissan Leaf teardown (part 1) (Mar. 2012)
Nissan Leaf teardown (part 2) (Sep. 2012)
Nissan Leaf teardown (part 3) (Nov. 2012)


Engine compartment before disassembly

 

Engine compartment before disassembly Engine compartment before disassembly
Top view of the engine compartment. The red arrow points to the auxiliary battery supplied by Furukawa Battery. The white arrow points to the transmission ECU supplied by Continental AG and the engine management system (EMS) supplied by Keihin. Bottom view of the engine compartment. The engine is contained on the left side of the silver panel at the center. The DCT with a built-in motor is to the right. The blue component at the center left is the oil filter.

 

 



Drive unit removal

 

Drive unit
Drive unit Drive unit
The removed drive unit as viewed from the front left of the vehicle (left-hand photo) and from the front right (right-hand photo).
The large black round component at the right end of the drive unit (left-hand photo) is the side cover supplied by ROKI. The motor and the 7-speed DCT are contained inside.
The silver component with many small projections at the center (right-hand photo) is the electric water pump supplied by Aisin Seiki. The high-voltage cable under the pump connects to the HVAC electric compressor supplied by Sanden. The cylindrical component (pointed by white arrow) to the right of the electric water pump is the starter motor supplied by Mitsuba. The dark component at the top is the intake manifold supplied by Nissin Kogyo.
Drive unit Drive unit
The removed drive unit as seen from the cabin. The silver cover pointed by the arrow contains a catalyst-integrated cooled EGR (exhaust gas recirculation) system. The bottom view of the engine compartment without the drive unit. The exhaust pipe was contained in the heat shield plate (center). The orange-colored cable to the right is the high-voltage cable that connects the IPU and the motor. The silver-colored component (pointed by arrow) on the upper right is the tandem motor cylinder of the electric servo brake system.

 

Engine
Engine Engine
The engine viewed from the vehicle's left without the 7-speed DCT with a built-in motor. The flywheel (clutch damper) supplied by Luk (a Schaeffler group company), about 280mm in diameter, is seen at the center bottom. The flywheel contains a damper that suppresses the engine vibrations. The round hole (pointed by arrow) by the flywheel is where the starter motor is located. It causes the ring gear located outside the flywheel to rotate and start the engine. The engine viewed from the vehicle's right with the chain-driven timing belt (cam chain) that drives the camshaft. The LDA engine on the previous model of the Fit had SOHC (Single OverHead Camshaft). The new LEB engine has DOHC (Double OverHead Camshaft). The black component between the upper and lower gears is the cam chain tensioner.

 

Engine top
Engine top Engine top
Inside of the engine top without the cylinder head cover. The white arrow points to the vehicle's front. The black component (pointed by red arrow) to the right of the left-hand photo contains the fuel injector.
The Fit Hybrid has the LEB type Atkinson cycle engine. The intake valve closing timing is delayed so that the expansion ratio gets larger than the compression ratio. The intake camshaft of the engine has the VTEC (Variable valve Timing and lift Electronic Control system) and electric VTC (continuously variable Valve Timing Control mechanism) to improve fuel efficiency and horsepower.
The VTEC has two different cam profiles, wide and narrow, to improve fuel efficiency and power output. The narrow profile cam has revolution-modulated valve control (REV) to improve the engine startability. The electric VTC with the electrified cam sprocket in the intake side (pointed by blue arrowhead) coordinates with the VTEC to increase the effect of the Atkinson cycle. This also provides an optimal control over the valve timing according to the driving condition.

 

VTEC hydraulic control valve Starter motor
VTEC hydraulic control valve Starter motor
The rear view of the VTEC hydraulic control valve supplied by Keihin. It is located outside of the intake camshaft. Refer to the upper right photo of the drive unit. Starter motor supplied by Mitsuba measures 200mm in length, 130mm in width, and 85mm in height. Normally, HV starts off on electric energy and the engine is started by the vehicle's driving force. The starter motor is installed for emergency purpose when EV starting is not available.

 

Cylinder head cover Electric compressor
Cylinder head cover Electric compressor
Cylinder head cover supplied by MAHLE. The four parts seen in a row are the ignition coils supplied by Hitachi Automotive Systems. Inside of the electric compressor. It is used for the first time in the new model.

 

Powertrain ECU
Powertrain ECU Powertrain ECU
Engine management system (pointed by red arrow) and transmission ECU (pointed by white arrow) are installed next to the auxiliary battery. They weigh 1.65kg. The engine management system (EMS) supplied by Keihin measures 160mm in length, 120mm in width, and 35mm in height.
Powertrain ECU Powertrain ECU
Front (left-hand photo) and back (right-hand photo) of the transmission ECU supplied by Continental. The ECU runs on transmission control system software co-developed by Luk (Schaeffler group company) and Honda. The ECU measures 140mm in length, 170mm in width, and 45mm in depth.

 

 



7-speed dual clutch transmission (DCT) with a built-in motor

 

Configuration Motor start power diagram
Configuration Motor start power diagram

 

Engine start power diagram Engine 2nd-gear drive +
motor 3rd-gear assist power diagram
Engine start power diagram Engine 2nd-gear drive + motor 3rd-gear assist power diagram

Drawn by MarkLines based on Honda's PR material

 

7-speed DCT with a built-in motor
7-speed DCT with a built-in motor 7-speed DCT with a built-in motor
7-speed DCT with a built-in motor viewed from the motor side (left-hand photo) and from the engine side (right-hand photo). The plastic side cover (black component in the left-hand photo) is retained in place with aluminum retainer bolts for weight reduction. An electric gear actuator was installed in the hole (pointed by red arrow) near the side cover.
The component pointed by the white arrowhead (right-hand photo) contains the final drive gear (which doubles as the differential). The black portion (pointed by blue arrow) connects to the driveshaft to drive the front wheels.

 

Dual clutch Electric gear actuator
Dual clutch Electric gear actuator
The dual clutch supplied by Luk (Schaeffler group company) weighs 15kg and measures 160mm in diameter and 130mm in height. The transmission side of the dual clutch (shown) contains the clutch that connects to the secondary shaft (even-numbered gear). The engine side contains the clutch that connects to the main shaft (odd-numbered gear).
The motor is connected to the main shaft (odd-numbered gear) and remains disconnected from the engine during EV mode driving.
Electric gear actuator supplied by Luk (Schaeffler group company).
See "7-speed DCT with a built-in motor" above about the location of the actuator.

 

Motor
Motor Motor
Motor with the black side cover removed (left-hand photo) and the silver cover removed (right-hand photo). The motor has a built-in angle sensor (motor resolver) at the center.
The motor is oil-cooled by splashing transmission oil to the coil. This increases the motor output while reducing the motor to a compact size.

 

Stator
Stator Stator
Stator (left-hand photo) and enlarged image of the rectangular coil (right-hand photo). The stator measures 270mm in diameter, 95mm in height, and 60mm in width. The coil is 18mm in length and formed by 2mm wide wire. The stator required hard work by four men to remove using slotted screwdrivers.

 

Rotor, planetary gear
Rotor, planetary gear Rotor, planetary gear
The removed rotor is held by hand next to the planetary gear (left-hand photo) and placed on a light blue sheet (right-hand photo). The rotor weighs about 4kg and measures 200mm in diameter. When the removed rotor was placed on an iron table, its magnetism was so strong that it could not be lifted by a hand.
At the rotor center are the planetary gear (pointed by red arrow) and the sun gear (pointed by blue arrow) of the main shaft (odd-numbered gear). The planetary gear functions as the 1st gear of the DCT and measures 110mm in diameter and 60mm in height.

 

7-speed dual clutch transmission (DCT)
7-speed DCT 7-speed DCT
7-speed DCT 7-speed DCT
The parted 7-speed DCT as viewed from the motor side (upper and lower left-hand photos) and from the engine and dual clutch side (upper and lower right-hand photos).
The right-hand photos show the final drive gear with the integrated differential (pointed by white arrow), the secondary (even-numbered gear) shaft (pointed by red arrow), the main (odd-numbered gear) shaft (pointed by blue arrow), the countershaft (pointed by purple arrow) and the reverse shaft (pointed by green arrow).
The silver-colored component (pointed by gray arrow) below the secondary shaft is the parking brake pole. A vehicle speed sensor is fitted at the tip of the final drive gear. Two drive shafts, the main shaft (odd-numbered gear) and the secondary shaft (even-numbered gear), are used. The planetary gear serves as the 1st gear. This design has led to a compact transmission that fits in the Fit Hybrid.

 

Electrohydraulic clutch actuator
Electrohydraulic clutch actuator Electrohydraulic clutch actuator
Electrohydraulic clutch actuator supplied by Delphi Automotive. The actuator has a motor inside that regulates the clutch. The cutaway model of the 7-speed DCT (right-hand photo) was exhibited at the "new technology presentation" held by Schaeffler Japan in October 2013. The white circle indicates the electrohydraulic clutch actuator. The red circle indicates the electric gear actuator.
The electrohydraulic clutch actuator runs on clutch control system software co-developed by Luk (Schaeffler group company) and Honda.

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