Assessment of Fuel Economy Technologies for Light-Duty Vehicles (2011) / Chapter Skim
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4 Spark-Ignition Gasoline Engines
4 Spark-Ignition Gasoline Engines
Pages 38-60
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From page 38... ...
by which fuel consumption benefits are realized along with the interactions that these technologies have with the base Thermodynamic Components engine architecture. As with the other vehicle technologies examined in this report, the committee's estimates of in- Thermodynamic factors include combustion interval, cremental reduction of fuel consumption and the costs of effective expansion ratio, and working fluid properties.
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From page 39... ...
I4 engines having displacement of roughly 1.8 L Gas Exchange or Pumping Losses or more require balance shafts to cancel the second-order shake forces. These are two counter-rotating balance shafts Gas exchange or pumping losses, in the simplest terms, running at twice crankshaft speed.
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From page 40... ...
THERMODYNAMIC FACTORS Variable Compression Ratio Fast-Burn Combustion Systems If an engine's compression ratio could be adjusted to near Fast-burn combustion systems are used to increase the knock-limited value over the operating range, significant the thermodynamic efficiency of an SI engine by reduc - fuel economy gains could be realized. Many mechanisms to ing the burn interval.
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From page 41... ...
These small variations result in a slightly different Fuel Consumption Benefit and Cost of IVC Timing charge mass from cylinder to cylinder, causing somewhat rougher idle engine operation, which is detrimental to cus OEM input suggests intake cam phasing results in roughly tomer satisfaction. a 1 to 2 percent fuel consumption reduction.
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From page 42... ...
V-engines with variable valve overlap in this manner tends to reduce pumping loss intake and exhaust would require four cam phasers, adding while the corresponding IVC event will occur earlier, thus roughly $140 of manufacturer cost based on manufacturer offsetting some of the increased-overlap benefit. At idle, input, but a portion of this is offset by the elimination of the too much valve overlap will destabilize combustion.
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From page 43... ...
-step cams that yield short intake durations to reduce pumping losses by varying the lift profile of the using DVVL can yield fuel consumption reductions in the camshaft. By varying the lift of the valves, it is possible 4 to 5 percent range based on vehicle OEM input.
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From page 44... ...
. resulting from effective use of internal gas recirculation." Reprinted Reprinted with permission from SAE Paper 2006-01-0223, Copy Copy Nissan evaluated the consumption benefits distribution at a right 2006 SAE International.
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From page 45... ...
The new system will first be applied to their newly developed 2.0-L engine. Toyota's system features separate cam phasers on the intake and exhaust camshafts to vary the camshaft timing, along with a production and the testing cycle used to produce this estimate continuously variable valve lift system.
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From page 46... ...
The decrease in losses reduces percent benefit when combined with variable valve timing the overall fuel consumption. Cylinder deactivation via (Sierra Research, 2008)
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From page 47... ...
Camless Valve Trains Fuel Consumption Benefit and Cost of Cylinder Deactivation A fully camless valve train eliminates the need for cam Vehicle OEMs estimate cylinder deactivation typically shafts, as well as various other supporting hardware, and yields fuel consumption reductions in the 6 to 10 percent operates the valves individually by means of actuators. This range on V8 configurations.
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From page 48... ...
from the market, and there was a return to conventional PFI Fuel consumption benefits of these homogeneous versions systems. It was believed that this withdrawal stemmed not are derived mainly from a knock-limited compression ratio only from disappointing sales but also because meeting upincrease (typically +1.0)
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From page 49... ...
Furthermore, reduction in the number of Fuel Consumption Benefit and Cost of Direct Injection cylinders, e.g., V6 to I4, may require countermeasures neces sary to satisfy NVH expectations. The increase in knock-limited compression ratio possible for DISI configurations would be expected to yield Implementation of Downsizing and Turbocharging a fuel consumption reduction in the 2 percent range based on vehicle OEM input, but the countervailing effect of Several conditions must be addressed in implementing pumping and parasitic loss increases may reduce this ben downsizing and turbocharging.
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From page 50... ...
is well known as a and turbocharged engines equipped with direct injection. means to reduce pumping losses and thereby increase fuel The company plans to offer these engines in nearly all its efficiency.
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From page 51... ...
Sierra claims that "turbocharging and engine upgrades, additional sensors and controls, and intake downsizing without the use of gasoline direct injection does and exhaust modifications. not yield benefits on a constant performance basis, based on The committee estimated that the manufacturing costs a statistical analysis of available CAFE data done in 2004" for integrating downsizing and turbocharging would be (Sierra Research, 2008)
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From page 52... ...
. Therefore, reducing friction is a constant aim of to mechanical distortion caused by the forces resulting from engine development for improved fuel economy.
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From page 53... ...
(2009) tested a small fuel consumption benefit may result along with a the fuel consumption benefit of LVL in different drive cycles.
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From page 54... ...
As system definiby way of the exhaust port. Typically, the high temperature tion, fuel consumption benefits, and costs are uncertain at of the exhaust that leaves the cylinder at the beginning of this time, HCCI is believed to be beyond the 15-year time the exhaust-valve open period is also characterized by its horizon of this study.
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From page 55... ...
The higher cost of only about 1 percent of the total fuel used, thus providing an applying cylinder deactivation to DOHC V6 and V8 engines, E85 refill driving range of ~20,000 miles with a 26-gallon combined with the reduced fuel consumption benefit when gasoline fuel tank and a 10-gallon E85 tank. For the higher cylinder deactivation is added to an engine with VVT, has load US06 driving cycle, E85 would constitute 16 percent caused most OEMs to avoid its application to DOHC engines.
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From page 56... ...
2006. Improvements to a four cylinder gasoline engine through the fully variable valve lift Finding 4.7: Variable compression ratio, camless valve and timing system univalve.
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From page 57... ...
SAE Paper 2004-01-0988. SAE International, Toyota Motor Company.
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From page 58... ...
, CCP 1.5-3.0 1.5-3.5 2.0-4.0 52.5 105 105 exhaust and intake valve timing events SOHC • Manufacturer cost estimate of $35/phaser • Short durations may reduce pumping loss, and the reduced lift is a consequence of this • As intake manifold vacuum vanishes, alternate Discrete variable means must be found to implement power valve lift (DVVL) , DVVL 1.5-3.0 1.5-3.0 2.0-3.0 195 240 270 315 420 480 brakes and PCV SOHC/DOHC • DVVL features two to three separate fixed profiles • Manufacturer cost estimate of $40/cylinder + $35/phaser ASSESSMENT OF FUEL ECONOMY TECHNOLOGIES FOR LIGHT-DUTY VEHICLES
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From page 59... ...
Range (%) Range Low High Low High Low High • Effectiveness depends on power to weight ratio, previously added technologies, NVH, and drivability issues • Reduction in pumping losses from higher Cylinder cylinder loading DEAC NA 4.0-6.0 5.0-10.0 NA 510 600 536 630 deactivation, SOHC • Higher cost when applied to OHC engines • Manufacturer cost estimate for OHC engines of $340 to $400 • Additional manufacturer cost of $140 for NVH SPARK-IGNITION GASOLINE ENGINES issues • Effectiveness depends on power to weight ratio, previously added technologies, NVH, and drivability issues Cylinder DEAC NA 4.0-6.0 5.0-10.0 NA 330 375 383 • Reduction in pumping losses from higher deactivation, OHV cylinder loading • OHV has a lower cost when compared to OHC setups • Implementations include intake cam phaser (ICP)
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From page 60... ...
phasing (DCP) • Manufacturer cost estimate of $35/phaser • Short durations may reduce pumping loss, and the reduced lift is a consequence of this • As intake manifold vacuum vanishes, Continuously alternate means must be found to implement variable valve lift CVVL 3.5-6.0 3.5-6.5 4.0-6.5 239 308 435 465 525 585 power brakes and PCV (CVVL)
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