ENGINE UNIT


  1. CONSTRUCTION


    1. Cylinder Head Cover


      1. A magnesium-alloy cylinder head cover is used to achieve significant weight reduction. By optimizing the shape, rib positions, and other factors, sufficient quietness has been ensured.

      2. An oil delivery pipe is installed inside the cylinder head cover. This ensures lubrication of the sliding parts of the roller rocker arms, improving reliability.

      3. By optimizing the blow-by gas intake position and fresh air intake positions, the ventilation efficiency has been improved.

      4. By providing ventilation baffle plates in the cylinder head cover, the amount of the oil taken away in the blow-by gas has been reduced to achieve reduced oil consumption and cleaner exhaust gas. In addition, a two-step type baffle plate is provided in the vacuum-side PCV chamber to prevent the engine oil splashed by the camshafts from being sucked into the blow-by gas intake port.

        A005FYME03
        Text in Illustration
        *1 Cylinder Head Oil Nozzle *2 PCV Valve
        *3 Baffle Plate No.1 *4 Baffle Plate No.2
        *a Cylinder Head Cover Cross Section *b Fresh Air
        *c Blow-by Gas - -

    2. Cylinder Head


      1. The cylinder head structure has been simplified by separating the camshaft housing (cam journal portion) from the cylinder head.

      2. The angle of the intake and exhaust valves has been narrowed and set at 21.5° to permit a compact cylinder head.

      3. A taper squish combustion chamber is used to improve anti-knocking performance and intake efficiency. In addition, engine performance and fuel economy have been improved.

        A005G6OE04
        Text in Illustration
        *1 Fuel Injector *2 Intake Port
        *3 21.5° *4 Taper Squish
        *5 Spark Plug *6 EGR Gas Passage
        *a Intake Side *b Exhaust Side

    3. Cylinder Block Sub-assembly


      1. An aluminum cylinder block with a 8 mm (0.31 in.) distance between the cylinder bores is used to achieve a compact and lightweight configuration.

        A005G8UE03
        Text in Illustration
        *1 8 mm (0.31 in.) - -

      2. Through the use of an offset crankshaft, the centerline of the cylinder bores is shifted 12 mm (0.47 in.) towards the exhaust in relation to the centerline of the crankshaft. Thus, the side force (thrust) applied to the cylinder walls is reduced when maximum combustion pressure is applied. This contributes to fuel economy.

        A005FPAE05
        Text in Illustration
        *1 12mm (0.47 in.) *2 Bore Centerline
        *3 Crankshaft Centerline *4 Offset Crankshaft
        *5 Non-offset Crankshaft *6 Maximum Pressure

    4. Oil Pan


      1. The oil pan is made of aluminum die-cast.

        A005FYEE02
        Text in Illustration
        *1 Oil Pan *2 Oil Strainer
        *3 Oil Pan No.2 - -

    5. Piston


      1. The pistons are made of aluminum alloy to allow them to be compact and lightweight.

      2. The piston head portion uses a taper squish shape to achieve fuel combustion efficiency.

      3. Semi floating type piston pins are used.

      4. Narrow-width piston rings are used to reduce weight and friction.

      5. The piston skirt is coated with resin to reduce friction losses.

        A005FYOE04
        Text in Illustration
        *1 Taper Squish Shape *2 No.1 Compression Ring
        *3 No.2 Compression Ring *4 Oil Ring
        *5 Cylinder Bore *6 Piston
        *7 Resin Coating - -

    6. Connecting Rod and Connecting Rod Bearing


      1. The connecting rods are made of high-strength steel for weight reduction.

      2. Plastic region tightening bolts are used to achieve a light weight.

      3. The width of the connecting rod bearings has been optimized to reduce friction.

      4. The lining surface of the connecting rod bearing is micro-grooved to provide an optimal oil clearance. As a result, cold-engine cranking performance has been improved and engine vibration has been reduced.

        A005FZXE03
        Text in Illustration
        *1 Connecting Rod *2 Micro-grooved
        *3 Connecting Rod Bearing *4 Plastic Region Tightening Bolt

    7. Crankshaft and Crankshaft Bearing


      1. The crankshaft has 5 main journals and 4 balance weights.

      2. The diameter and width of the pins and journals have been reduced, and the pins for the No.1 and No.4 cylinders have been made highly rigid to realize a lightweight and low-friction performance.

      3. A crank position sensor rotor is pressed into the crankshaft to realize an integrated configuration.

        A005FT7E04
        Text in Illustration
        *1 Crank Position Sensor Rotor *2 Oil Hole
        *3 Balance Weight *4 No. 5 Journal
        *5 No. 1 Journal - -

      4. The width of the crankshaft bearings has been optimized to reduce friction.

      5. The lining surface of the crankshaft bearing is micro-grooved to provide an optimal oil clearance. As a result, cold-engine cranking performance has been improved and engine vibration has been reduced.

      6. An oil groove is provided on each upper main bearing (crankshaft bearing). The oil groove is deep at the center and is shallow at the edges to reduce the amount of oil that will leak from the crankshaft bearing. As a result, the size of the oil pump has been reduced, thus minimizing friction.

        A005G2ME05
        Text in Illustration
        *1 Upper Main Bearing (Crankshaft Bearing) *2 Lower Main Bearing (Crankshaft Bearing)
        *3 Micro-grooved *4 Center
        *5 Edge *6 Oil Groove Depth

    8. Valve Mechanism


      1. Intake and exhaust efficiency has been increased due to the larger total port areas.

      2. The valve mechanism uses a roller rocker arm with built-in needle bearings. This reduces the friction that occurs between the cams and the areas on the roller rocker arms that push the valves down, thus improving fuel economy.

      3. Hydraulic lash adjusters, which maintain a constant zero valve clearance through the use of oil pressure and spring force, are used.

      4. The intake camshaft and exhaust camshaft are driven by a timing chain.

      5. This engine uses the Variable Valve Timing-intelligent (VVT-i) system which controls the intake camshaft to provide optimal valve timing according to driving conditions. With this, lower fuel consumption, higher engine performance, and exhaust emission have been reduced.

        A005G92E02
        Text in Illustration
        *1 No. 2 Chain Vibration Damper *2 Exhaust Camshaft
        *3 VVT-i Controller *4 Intake Camshaft
        *5 Roller Rocker Arm *6 Hydraulic Lash Adjuster
        *7 Intake Valve *8 Exhaust Valve
        *9 No. 1 Chain Vibration Damper *10 Chain Slipper
        *11 Chain Tensioner - -

    9. Camshaft


      1. Oil passages are provided in the camshaft in order to supply engine oil to the VVT-i system.

      2. A VVT-i controller has been installed on the front of intake camshaft to vary the timing of the intake valves.

      3. A timing rotor for the camshaft position sensor is provided at the back end of the intake camshaft.

        A005G86E02
        Text in Illustration
        *1 Exhaust Camshaft *2 Timing Rotor
        *3 Intake Camshaft *4 Oil Passage (Retard)
        *5 Oil Passage (Advance) *6 VVT-i Controller (Camshaft Timing Gear Assembly)

    10. VVT-i Controller


      1. The VVT-i controller consists of a housing driven from the timing chain and a vane coupled with the intake camshaft.

      2. The VVT-i controller have a 4-blade vane.

      3. The oil pressure sent from the advanced or retarded side path at the intake camshaft causes rotation in a camshaft timing gear assembly vane circumferential direction to vary the intake valve timing continuously.

      4. When the engine is stopped, a lock pin locks the intake camshaft at its most retarded position, to ensure that the engine starts properly.

      5. An advance assist spring is provided on the exhaust side camshaft timing gear assembly. This spring applies torque in the advance direction when the engine is stopped, thus ensuring the engagement of the lock pin.

        A005G9SE02
        Text in Illustration
        *1 Oil Pressure *2 Housing
        *3 Intake Camshaft *4 Lock Pin
        *5 Vane - -
        *a Lock Pin Operation *b Engine Stopped
        *c Engine Operating *d Retard
        *e Advance - -

    11. Hydraulic Lash Adjuster


      1. A hydraulic lash adjuster is located at the fulcrum of each roller rocker arm. A hydraulic lash adjuster consists primarily of a plunger, a plunger spring, a check ball, and a check ball spring.

      2. The hydraulic lash adjuster is actuated by the engine oil, plunger spring, and check ball spring. The oil pressure and the spring force that act on the plunger push the roller rocker arm against the cam, in order to adjust the valve clearance. This reduces the engine noise that is created during the opening and closing of the valve.

        A005FSOE02
        Text in Illustration
        *1 Plunger *2 Oil Passage
        *3 Cam *4 Roller Rocker Arm
        *5 Hydraulic Lash Adjuster *6 Check Ball Spring
        *7 Plunger Spring *8 Check Ball

        Tech Tips

        Valve clearance adjustment is not necessary because hydraulic lash adjusters are used.

    12. Timing Chain and Chain Tensioner


      1. A timing chain with an 8 mm (0.31 in.) pitch is used to make the engine more compact.

      2. The chain tensioner uses a spring and oil pressure to maintain proper chain tension at all times.

      3. The chain tensioner suppresses noise generated by the timing chain.

      4. The chain tensioner is a ratchet type tensioner with a non-return mechanism.

        A005FYXE02
        Text in Illustration
        *a Chain Tensioner Operation - -
        *1 Chain Tensioner *2 Chain Tensioner Slipper
        *3 Timing Chain *4 No. 2 Chain Vibration Damper
        *5 No. 1 Chain Vibration Damper *6 Crankshaft Timing Sprocket

    13. Timing Chain Cover Assembly


      1. An aluminum die-cast timing chain cover is used.

      2. The timing chain cover has an integrated construction including parts of the cooling system (water pump and water passage) and the lubrication system (oil pump and oil passage). Thus, the number of parts has been reduced for weight reduction.

        A005FSGE02
        Text in Illustration
        *1 Timing Chain Cover Assembly *2 Water Pump Assembly
        *3 Oil Pump Housing *4 Oil Pump Rotor

    14. V-ribbed Belt


      1. Accessory components are driven by a serpentine belt consisting of a single V-ribbed belt. This reduces the overall engine length, weight and the number of engine parts.

        A005G9VE02
        Text in Illustration
        *1 Crankshaft Pulley *2 Generator Pulley
        *3 Water Pump Pulley *4 Cooler Compressor Pulley