Weight Reduction Technology

Weight has a significant effect on a vehicle’s basic ability to go, corner and stop. Furthermore, environmental and economic factors such as fuel economy are also strongly influenced by vehicle weight.
Mazda strives to minimize the weight of every car it develops. The all-new Mazda2 (Demio) launched in July 2007 is a perfect example. During development, each individual part was examined and any unnecessary material was removed. The finished vehicle is around 100 kilograms lighter than the first generation Mazda2.
Mazda is committed to continually improve driving dynamics and fuel efficiency by deploying its lightweight technologies and resistance reduction techniques.

A dedicated team was formed to develop and test weight reduction techniques for the all-new Mazda2 well before actual vehicle development began. The team employed cutting-edge simulation software to analyze various methods. These were then tested against vehicle driving dynamics using prototype models.
This advanced technology development, conducted for Mazda’s new compact car, resulted in the creation of an impact absorbing concept that uses a new body framework and high tensile steel. Spot welding and weld bonds were also employed to strengthen specific locations that are subjected to greater loads. This has become Mazda’s new approach to weight management.

• Bonnet

With a smaller striker assembly and thinner hinges, the bonnet saves 0.69kg.

• Body Shell

Smaller dimensions alone would have lowered the weight of the body shell by four kg, to 233 kg. Measures needed to increase rigidity and crash resistance would have then raised it up to 244 kg. But thanks to an optimised body structure, weight was reduced to 215 kg, 22 kg less than the old Mazda 2.

• Door-Mounted Speakers

Mazda’s weight watchers were also at work with the door-mounted speakers. By changing the magnets from a ferrite type to neodymium, and making the plastic moulding single-peace, a total weight savings of 0.98 kg was achieved.

• Intake and Cooling Systems

For the intake system, Mazda engineers moved the fresh air inlet from its original position behind the left headlamp to the top of the radiator shroud. This new position removed the need for the resonator and baffle.

• Suspension

Mazda weight specialists were able to save a impressive 13 kg using weight optimising measures in the suspension. These included making the trailing arm on the rear axle shorter and giving the front lower arms an open-section structure. This reduction in unsprung weight means both better handling and ride comfort.

• Exhaust System

Mazda eliminated the underfoot catalyst, and for the 1.3-litre petrol model, the presilencer used in the Mazda2 until now was also eliminated.

• Other points

The shift lever assembly, base plate thickness and rib configuration for automatic transmission models were optimized. The shift knob itself was also made smaller and its positioning was improved. These changes saved 0.85 kilograms.

Idling Stop Technology | i-stop

Idle stop systems save fuel by shutting down a vehicle’s engine automatically when the car is stationary and restarting it when the driver resumes driving. Especially in urban areas, drivers often let their car’s engine idle at traffic lights or when stopped in traffic jams. Switching off the engine to stop it idling in these situations enhances fuel economy by about 10% under Japan’s 10-15 mode tests.

Conventional idling stop systems restart a vehicle’s engine with an electric motor using exactly the same process as when the engine is started normally. Mazda’s ”i-stop”, on the other hand, restarts the engine through combustion. Mazda’s system initiates engine restart by injecting fuel directly into a cylinder while the engine is stopped, and igniting it to generate downward piston force. This system not only saves fuel, but also restarts the engine more quickly and quietly than a conventional idle-stop system.

• Piston stop position control and combustion restart technology

In order to restart the engine by combustion, it’s vital for the compression-stroke pistons and expansion-stroke pistons to be stopped at exactly the correct positions to create the right balance of air volumes. Consequently, Mazda’s ”i-stop” effects precise control over the piston positions during engine shutdown. With all the pistons stopped in their optimum position, the system restarts the engine by identifying the initial cylinder to fire, injecting fuel into it, and then igniting it. Even at extremely low rpm, cylinders are continuously selected for ignition, and the engine quickly picks up to idle speed.

Thanks to these technologies, the engine will restart with exactly the same timing every time and will return to idle speed in just 0.35 seconds, roughly half the time of a conventional electric motor idling stop system. As a result, drivers will feel no delay when resuming their drive. With the ”i-stop”, Mazda can offer a comfortable and stress-free ride as well as better fuel economy.

SKYACTIV TECHNOLOGY

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.

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