2010 - LAT Features and Benefits

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2010 Ecotec 2.4L I-4 Hybrid (LAT)
ECOTEC 2.4L I-4 HYBRID (LAT) CAR ENGINE

Hybrid powertrain for 2010 Chevrolet Malibu.
Electric Motor/Generator Unit
Dual-Transfer High-Torque Accessory Drive with Dual-Arm Tensioning Mechanism
Nickel Metal-Hydride (NiMH) Battery
E67 Engine Control Module
Cooled Power Electronics
Seven-Rib High Strength Crank Pulley
Dual Catalytic Converters


Full Description of Carryover Features from 2009 model year

Hybrid powertrain for 2010 Chevrolet Malibu
The Ecotec 2.4L Hybrid’s internal combustion engine is similar to the Ecotec 2.4L VVT (RPO LE5), with all its premium features, including fully variable valve timing. The Ecotec 2.4L Hybrid engine is matched to the Hydra-Matic 4T45 four-speed automatic transmission developed specifically for GM’s new Hybrid system.

The objective in developing the GM Hybrid system for the Chevrolet Malibu, was flexible, cost effective design. Key components include a unique electric motor/generator unit, a dual-tensioning belt drive and sophisticated electronic controls. The GM Hybrid system delivers increased fuel economy thanks to engine shut-off during stops and fuel cut-off during deceleration. The motor/generator unit supplies electric power assist during acceleration and generates electrical energy through regenerative braking.

With the assistance of the Ecotec 2.4L Hybrid engine, and combined with the GM Hybrid System, the applications will deliver a significant fuel economy improvement compared to a more conventional gasoline-only applications. Its price premium is expected to be considerably less than that for other hybrid cars currently available. The 2.4L Hybrid’s gasoline engine generates 164 horsepower and smooth torque delivery that comes with full variable valve timing and electric power assist from the electric motor/generator unit augmenting the torque available during acceleration.

Electric Motor/Generator Unit
An Electric Motor/Generator Unit (MGU) distinguishes the 2.4L Hybrid engine from other Ecotec 2.4L engines. The MGU concept differs from that applied in other current hybrid vehicles, including the Parallel Hybrid Technology in GM’s industry first full-size hybrid pickups.

Sometimes called a belt starter-alternator, the MGU is a precision device mounted on the engine block in place of the conventional alternator and connected to the gasoline engine’s crankshaft by a drive belt. The GM Hybrid system’s MGU provides 115 lb-ft of auto-start torque--more than the peak torque generated by the 1.5-liter gasoline engines used in some of today’s small cars—and 3000 watts of continuous generating power. The MGU has its own controller, which reports to the Engine Control Module. Its purpose is three-fold: restart the gasoline engine after it shuts off to conserve fuel, augment the engine during acceleration or heavy vehicle load, and generate electricity that’s stored in an advanced nickel metal-hydride (NiMH) battery.

The GM Hybrid system’s MGU does three things seamlessly, in a fashion that’s largely transparent to the Aura hybrid driver. The MGU is managed by advanced control and power electronics, and it operates in either motor or generator mode according to the circumstances of driving.

In motor mode, the NiMH battery converts its stored chemical energy into direct current (DC) electricity. The power electronics then invert the DC power to three-phase alternating current (AC), which runs the MGU as an electric motor and transfers energy through the drive belt to the gasoline engine’s crankshaft. The MGU almost instantly restarts the gasoline engine when the driver steps on the accelerator, as when a traffic signal turns green. It also provides a brief acceleration boost as needed. Conventional 12-volt accessory power, which operates everything from the headlights to the stereo, can also be generated in motor mode.
In generate mode, power flows from the 2.4L gasoline engine to the MGU, rather than the other way around. This occurs during normal acceleration, constant speed driving, or by capturing kinetic energy from the rolling vehicle as it decelerates with fuel delivery cut off. The crankshaft turns the MGU, which operates as a generator creating three-phase AC. Now the power electronics change the AC power to DC and charge both the NiMH battery and the 12-volt lead-acid accessory battery.
The GM Hybrid system coupled with the 2.4L hybrid engine increases fuel economy significantly, at a much lower cost to the customer than other automotive hybrid systems currently available.

Dual-Transfer High-Torque Accessory Drive with Dual-Tensioning Mechanism
One key to the GM Hybrid System’s success—perhaps the most important element—is the drive belt that operates the Motor/Generating Unit (MGU) and other conventional accessories such as the air-conditioning compressor. The challenges developing this accessory drive were nearly as great as the demands placed on the belt itself.

The GM Hybrid’s accessory drive must transfer torque that is at minimum three times greater than the torque required to turn conventional accessories—enough torque to tear a conventional serpentine belt to shreds. Moreover, it must carry energy in two different directions: from the engine’s crankshaft to the MGU in generating mode, and from the MGU to the crank in motor mode. Finally, the belt drive must perform to a higher standard than a conventional accessory belt in extremes of cold, heat and moisture. Some slippage that may be acceptable in a conventional belt drive—for instance when the pulleys are damp—could not be tolerated in the 2.4L Hybrid. The MGU must restart the gasoline engine on its first attempt, every time, and conceivably dozens of times in a single trip.

GM engineers began by using math-based tools and trial-and-error prototypes to optimize the belt’s geometry. They then specified a belt up to the engine’s demands. The 2.4L Hybrid’s drive belt has seven ribs, or V-shaped treads around its inner circumference, compared to as few as three ribs in some automotive belts. The belt is manufactured from a purpose-formulated Ethylene Propylene Diene Monomer (EPDM) compound, with a core of aramid (more commonly known by the brand name Kevlar). Finally, GM developed an innovative belt tensioner unlike any used previously in automotive applications.

The 2.4L Hybrid’s tensioner has dual spans joined with a pivot. One is a conventional sprung mechanical tensioner, and the other is a hydraulic tensioner. Together, they keep the heavy-duty belt at a precise tension that provides enough friction to turn the MGU and enough flexibility to last through hundreds of thousands of restarts, even in extreme cold temperatures.

The result is a belt drive that is up to the demands of turning both the MGU and the engine’s crankshaft, and one that operates as quietly as GM’s other accessory belts, with the same anticipated useful life.

Nickel Metal-Hydride (NiMH) Battery
A NiMH battery pack powers the GM Hybrid’s MGU in motor mode, and is recharged by the MGU in generate mode. The battery is capable of delivering 14.5 kW peak power. Until recently, NiMH battery technology was reserved for wrist watches and small electronic appliances like telephones. In a sense, the GM Hybrid NiMH battery is like a giant watch battery, with an anticipated useful life of at least seven years. As hybrid vehicle batteries go, it is compact, and does not significantly hamper utility.

E67 Engine Control Module
GM’s new E67 Engine Control Module (ECM) manages all systems in the Ecotec 2.4L Hybrid, including both MGU and gasoline engine operation. It’s one of three ECMs in a family that will run nearly all the engines in GM Powertrain’s line-up. The E67 features 32-bit processing, compared to the conventional 16-bit processing in previous Ecotecs. It operates at 59 MHz, with 32 megabytes of flash memory, 128 kilobytes of RAM and a high-speed CAN bus. It synchronizes hundreds of functions, from spark timing to cruise control operation to MGU management.

The E67 validates the family strategy behind GM’s latest ECMs. While it adds unique Hybrid Supervisory software for the 2.4L Hybrid, it’s identical to the controller that directs such engines as the 4.4L Northstar V8 SC in the Cadillac XLR-V
Common controllers reduce development costs. The family of ECMs allows engineers to apply standard manufacturing and service procedures to all powertrains, and to quickly upgrade certain engine technologies while leaving others alone. They create both assembly and procurement efficiencies, as well as volume sourcing. In short, the new family of controllers creates a solid, flexible, efficient foundation, allowing engineers to focus on innovations and get them to market more quickly.

Cooled Power Electronics
The Ecotec 2.4L Hybrid power electronics do very sophisticated work in a demanding environment. They repeatedly switch the MGU from motor to generator in fractions of a second, cycle current in different directions, invert DC battery power to three-cycle AC and vice-versa, all the while sorting 12-volt DC to power accessories, and they do this inside an engine bay where extreme heat and a multitude of vibrations of various frequency are a fact of life. To stack the odds, GM Powertrain engineers have secured the 2.4L Hybrid’s voltage regulator, MGU controller, inverters and other components in a vibration-dampened aluminum shell the size of a small briefcase. The case is mounted to the right side of the engine ( as seen from the front of the vehicle ) and fed with coolant tapped from the front of the cylinder block.

Seven-Rib High Strength Crank Pulley
In combination with the Ecotec 2.4L Hybrid’s high-torque accessory drive system, the engine is equipped with a high-strength crank pulley that matches the drive belt’s seven-rib design. Other accessory pulleys are also more robust.

Dual Catalytic Converters
The Ecotec 2.4L Hybrid uses two catalytic converters, including a close-coupled, fast light-off catalyst just past the exhaust manifold in the exhaust stream. Because the exhaust ports and exhaust manifold heat more rapidly than any part of an engine, moving a smaller catalytic converter closer to the manifold in turn allows the catalyst to heat more quickly. So positioned, the catalytic converter achieves light-off—the temperature at which exhaust emissions are most efficiently oxidized--more quickly. This considerably lowers emissions during cold starts—a brief period when an engine operates at its highest emissions level and a critical phase in government certification tests.

Overview
The hybrid system coupled with the Ecotec 2.4L I-4 Hybrid engine will deliver a considerable fuel economy improvement compared to a conventionally powered passenger vehicles, yet its price premium is expected to be much lower compared to other hybrids.

The Ecotec 2.4L Hybrid engine takes a simple, straightforward concept and executes it with sophisticated technology. Its internal-combustion engine is based closely on the Ecotec 2.4L VVT (RPO LE5) introduced for model year 2006 in several cars and trucks, including the Chevrolet HHR and Pontiac Solstice, and it further validates the strategy behind the Ecotec line of four-cylinder engines.

Often referred to as the global four cylinders, the Ecotecs harness GM's global design and engineering capability by applying the best practices of technical centers in Europe and North America. The Ecotec 2.2L (RPO L61) created a blueprint for subsequent global powertrain development. It also laid the foundation for a line of engines that share core components with minimal casting changes, yet deliver unique performance and market characteristics with a range of displacements, fuel-delivery and induction systems and front-, rear- and all-wheel drive applications in both cars and trucks. Since launch of the original Ecotec in 2000, turbocharged and supercharged engines, others with full two-cam phasing and direct gasoline injection--and now a hybrid-- have been developed on the same basic architecture.

The Ecotecs have undergone the most demanding, comprehensive test and validation process in GM history, and the 2.4L Hybrid engine demanded even more. This engine will conceivably be started and stopped in excess of a million times over its life, and GM conducted additional lab and vehicle tests to make sure it was up to the job. It certainly is, and without the need for additional durability enhancements specific to the hybrid.

With good specific output, acceleration assist from its MGU and the broad torque delivery that comes with fully variable valve timing, this hybrid delivers good performance. Factor in the improved fuel economy at a reasonable price, and the message is clear. The Ecotec 2.4L I-4 Hybrid makes in very easy to be green.