Technical Innovations
AVL measures up to emissions
 AVL North America introduced a new tunnel design for its SPC-472 sampler that achieved full-flow constant volume sampler (CVS) correlation for particulate testing. |
AVL North America made several major announcements at the SAE 2002 World Congress, including the introduction of a new tunnel design for its SPC-472 sampler. According to William Silvis, Director of Research and Development at AVL, the design achieves full-flow constant volume sampler (CVS) correlation for particulate testing, producing partial flow system results comparable to those from more expensive full-flow equipment. "This is of particular significance when we consider the standardization efforts under way to develop a worldwide method for testing and sampling heavy-duty diesel engines," he said.
Transient partial-flow systems have historically experienced two types of deposition losses—diffusion and thermophoretic—inside the sampling system. According to AVL emissions specialist Norbert Kreft, AVL modified the probe, transfer tube, and tunnel to minimize those losses. A shorter probe length and thinner probe wall, combined with additional insulation to the mixing point, contributes to reductions in thermophoretic losses. The thinner tube material allows for a quicker assimilation of the exhaust temperature, reducing particulate loss. An adjustment of the angle within the re-circulation zone diffuses the sample throughout the mixing zone and reduces deposits.
To compensate for system time delays, the SPC-472 implements "look-ahead" controlling, which "uses a pre-recorded exhaust flow signal to control the partial flow sampling system," said Kreft. Accurate sampling methods rely on keeping the sample flow in direct proportion to the engine exhaust flow. "For emissions calculations, the actual measured flow is used. For controlling, a pre-recorded signal is time-shifted to completely compensate for unavoidable systemic and pneumatic time delays."
 The AVL BMD 150 is shown with a mass-flow controller inside a heated enclosure. |
AVL also introduced a partial-flow, bag-sampling system, or bag mini-diluter (BMD), for measuring the emissions from super ultra-low emitting vehicles (SULEVs). AVL claims the BMD-150 exceeds the basic requirements outlined by the AIGER consortium, including a flexible dilution circuit to provide the proper performance on a wide range of fuel types, from methanol and compressed natural gas to clean, reformulated gasoline.
The U.S. EPA encourages the use of BMD sampling systems for all future low-emissions measurements because they measure exhaust emissions more accurately than traditional CVS units. According to the EPA, BMD systems eliminate water condensation, minimize and optimize the dilution ratio and effects of dilution gas background concentrations, and reduce system-generated hydrocarbons.
"Such partial-flow systems (as BMD) will be adopted as a worldwide standard for testing heavy-duty diesel engines and are under consideration in the U.S. for regulating off-road engines," said Gerald Marek, AVL Global Product Manager of SPC systems.
- Jean L. Broge
Southco and Cat collaborate on latch
 Southco and Caterpillar collaborated on a heavy-duty compression latch for tractors and tracked loaders that enabled the machines to meet European legislation on noise emissions.  |
Southco engineers in Worcester, UK, worked with a Caterpillar engineering team in Grenoble, France, to develop a heavy-duty latch for Cat's small- and medium-size tractors and large tracked loaders.
"The design of this latch originated with a requirement from Caterpillar, who wanted the compression feature of our standard latches in a design that would install quickly and easily, be flush with their panels, have a folding handle for easy opening, and be key-lockable with the CAT key," said Irène Le Covec, Southco Industry Manager. "(Cat) also wanted a more modern, aesthetic design and wanted the latch color-matched to the CAT standard color."
Southco engineers visited Cat engineers in France to better comprehend Cat's application requirements. They modified the design and function of the latch, such as in the redesign of the lockplug's pawl to allow full adjustability and reduce the inside protrusion of the shaft by 10 mm (0.4 in), while high-performance anti-vibration washers were added to eliminate potential loosening of the pawl during operation of the equipment. The latch housing was also modified and strengthened to meet Cat's requirements for force and vibration resistance.
The new latch design also enabled Cat to meet the European Directive 2000/14/EC relating to noise emissions in the environment by equipment for use outdoors. The latch's "pull-up" mechanism compresses the thicker gaskets that Cat is using to meet this directive and obtain the CE mark on their products.
Throughout the project, Southco supplied Cat with more than 200 samples for evaluation and testing. Southco also conducted extensive FMEA and other testing in-house, which was carefully reviewed by the Cat team before the product was approved.
After successfully passing all applicable Cat testing, including a 500-h "shake" test, the latch was approved and is available for use throughout new and re-designed Cat product platforms. Southco launched the new latch to the global Caterpillar organization in June 2001.
- Jean L. Broge
