Next-Generation ‘SKYACTIV’ Technologies |

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Highlights of the SKYACTIV technologies:

  • SKYACTIV-G: a next-generation highly-efficient direct-injection gasoline engine with the world’s highest compression ratio of 14.0:1
  • SKYACTIV-D: a next-generation clean diesel engine with the world’s lowest compression ratio of 14.0:1
  • SKYACTIV-Drive: a next-generation highly-efficient automatic transmission
  • A next-generation manual transmission with a light shift feel, compact size and significantly reduced weight
  • A next-generation lightweight, highly-rigid body with outstanding crash safety performance
  • A next-generation high-performance lightweight chassis that balances precise handling with a comfortable ride

 

– First product to be equipped with SKYACTIV technology will be a Mazda Demio featuring an improved, fuel-efficient, next-generation direct-injection engine that achieves fuel economy of 30 km/L.

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Overview of the SKYACTIV technologies

1. SKYACTIV-G
A next-generation highly-efficient direct-injection gasoline engine that achieves the world’s highest gasoline engine compression ratio of 14.0:1 with no abnormal combustion (knocking)
  • The world’s first gasoline engine for mass production vehicles to achieve a high compression ratio of 14.0:1
  • Significantly improved engine efficiency thanks to the high compression combustion, resulting in 15 percent increases in fuel efficiency and torque
  • Improved everyday driving thanks to increased torque at low- to mid-engine speeds
  • A 4-2-1 exhaust system, cavity pistons, multi hole injectors and other innovations enable the high compression ratio
2. SKYACTIV-D
A next-generation clean diesel engine that will meet global emissions regulations without expensive NOx after treatments — urea selective catalytic reduction (SCR) or a Lean NOx Trap (LNT) — thanks to the world’s lowest diesel engine compression ratio of 14.0:1
  • 20 percent better fuel efficiency thanks to the low compression ratio of 14.0:1
  • A new two-stage turbocharger realizes smooth and linear response from low to high engine speeds, and greatly increases low- and high-end torque (up to the 5,200 rpm rev limit)
  • Complies with global emissions regulations (Euro6 in Europe, Tier2Bin5 in North America, and the Post New Long-Term Regulations in Japan), without expensive NOx after treatment
3. SKYACTIV-Drive
A next-generation highly efficient automatic transmission that achieves excellent torque transfer efficiency through a wider lock-up range and features the best attributes of all transmission types
  • Combines all the advantages of conventional automatic transmissions, continuously variable transmissions, and dual clutch transmissions
  • A dramatically widened lock-up range improves torque transfer efficiency and realizes a direct driving feel that is equivalent to a manual transmission
  • A 4-to-7 percent improvement in fuel economy compared to the current transmission
4. SKYACTIV-MT
A light and compact next-generation manual transmission with crisp and light shift feel like that of a sports car, optimized for a front-engine front-wheel-drive layout
  • Short stroke and light shift feel
  • Significantly reduced size and weight due to a revised structure
  • More efficient vehicle packaging thanks to its compact size
  • Improved fuel economy due to reduced internal friction
5. SKYACTIV-Body
A next-generation lightweight, highly-rigid body with outstanding crash safety performance and high rigidity for greater driving pleasure
  • High rigidity and lightness (8 percent lighter, 30 percent more rigid)
  • Outstanding crash safety performance and lightness
  • A "straight structure" in which each part of the frame is configured to be as straight as possible. Additionally, a "continuous framework" approach was adopted in which each section functions in a coordinated manner with the other connecting sections
  • Reduced weight through optimized bonding methods and expanded use of high-tensile steel
6. SKYACTIV-Chassis
A next-generation high-performance lightweight chassis that balances precise handling with a comfortable ride feel to realize driving pleasure
  • Newly developed front strut and rear multilink suspension ensures high rigidity and lightness (The entire chassis is 14 percent lighter than the previous version.)
  • Mid-speed agility and high-speed stability — enhanced ride quality at all speeds achieved through a revision of the functional allocation of all the suspension and steering components

Mechanical Engineering Interview Questions

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  • What is the function of EGR valve

EGR means Exhaust Gas Recirculation. The main function of EGR is to control NOx emission from the engine. At elevated temperature (during long run & full condition)if due to some reasons engine gets heated up beyond certain level… it produces NOx emission. In order to avoid this pollution , we have to control the temperature rise inside the cylinder. This can be achieved by mixing some amount of exhaust gas with intake air. By doing this the temperature inside the combustion chamber is reduced. And NOx is controlled.

  • What is the difference between Critical speed & Whirling speed?

In Solid mechanics, in the field of rotor dynamics, the critical speed is the theoretical angular velocity which excites the natural frequency of a rotating object, such as a shaft, propeller or gear. As the speed of rotation approaches the objects natural frequency, the object begins to resonate which dramatically increases system vibration. The resulting resonance occurs regardless of orientation.

Whirling Speed is due to the unbalanced forces acting on a rotating shaft.

  • What is the significance of Torque(in N-m) given in the engine specification ?

It give the moment about any point or simple rotation.

  • What is the abbreviation of Welding rod 7018?

7018=

70=tensile strength 70000psi

1= welding position

8=current flux

  • In ultrasonic machining the tool is made of
    1. High speed steel
    2. Diamond
    3. Plain carbon
    4. Brass & Copper

Answer:

Plain carbon

  • What are the uses of Graphite electrode in various field.

Graphite electrode is used in EDM and in Battery cells. It is also used in electric arc furnaces to melt the steel .

  • When a 40 watt lamp is connected in series with a 100 Watts lamp across a 220 V supply which one glows brighter
    1. 100 watt lamp
    2. 40 watt lamp
    3. Both will glow with equal brightness
    4. It cannot be predicted

Answer:

40 watt lamp

Reason:

When connected in series, the current through each lamp is same. But resistance of 40 W lamp is more. Therefore greater heat is produced in the 40W lamp.

  • Difference between TIG & MIG welding

Tungsten inert gas welding-non consumable electrode

MIG-Metal inert gas welding-uses consumable electrode

  • Specific speed of turbine?

The specific speed is defined as the the speed of the geometric turbine which can produce unit power at unit head

  • Material of Aircraft turbine blade?

Ni, Cr, Al, Traces of C

  • Do you know epicyclic gear box? What are the practical application of epicyclic gear box?

Epicyclic gear box consists of sun gear planetary gears and an annular called ring gear. Different speed ratios are obtained by locking any one gear. If you lock any two gear, direct gear will be obtained mostly used in overdrives. Wrist watch is a practical application of epicyclic gear box

  • What do you mean by super critical above 500MW in Thermal power plant?

In super critical boiler means all the steam to converted in to superheated steam at outlet of boiler no need to sent
to super heater once again.