Top 10 Technologies 2000
Camless engine
Siemens Automotive is developing a second-generation electromagnetic valve train (EVT). The full-load capability of the system at maximum speeds has already been demonstrated in a 16-valve four-cylinder engine. The key component of the infinitely variable electromechanical valve train is an armature-position sensor that simultaneously assures energy- and noise-reducing-control characteristics. Each actuator has a position sensor and is individually electronically controlled. In this manner, the valve timing can be adjusted as required within the physical limits of actuator operation. Thus, this valve control technology results in reduced fuel consumption and emissions as well as improved torque in spark-ignited engines.
The demonstration engine on a test dynamometer in Regensburg, Germany, is equipped with 16 valve actuators and the corresponding armature-position sensors, the Electronic Valve Control Unit (EVCU), a modified engine management Electronic Control Unit (ECU), and two cable rails connecting the actuators to the EVCU. The engine control transmits the actuator signals to the valve control system via a CAN bus. The system operates with an electrical distribution system voltage of 42 V generated by a crankshaft-mounted starter-generator.
The actuators work according to the free spring-mass-oscillator principle. A special software algorithm is used to control the actuator coil currents so that the valves are decelerated to a speed near zero as they land - in conjunction with a switching time of barely three milliseconds. It was this very soft landing feature that permitted the advantages of a cam-controlled valve train - soft touchdown of the valves on the valve seat - to be transferred to the electromechanical principle.
For the valves this means minimal wear and minimum noise generation. Without a software-based problem solution, the increased force exerted by the solenoid on the armature pole face as the air gap diminishes would result in very high impact speeds. This would produce mechanical and acoustic loads that would preclude continuous system operation.
The EVCU's other responsibility - in addition to managing valve timing - is to take on actuator-specific tasks such as the current control in the actuator coils. The armature-position sensor installed in the actuator housing also supplies the current values using a safe actuator control mechanism and provides important diagnostic information.
Navistar, Siemens partner for Green Diesel Technology
 Siemens is helping to develop this low-pressure digital valve fuel injector for use in Navistar's common-rail diesel fuel system. |
Navistar International Corp. says that its Green Diesel Technology, used in conjunction with ultra-low-sulfur diesel fuel, represents the next critical step toward cleaner diesel engine emissions technology without sacrificing engine durability, performance, or fuel economy. The company recently demonstrated the technology in Philadelphia, where the EPA held hearings on the agency's proposed Tier 2 emissions standards for passenger vehicles and light trucks.
The technology was incorporated in an AmTran RE school bus powered by an International T 444E diesel engine. The bus also was equipped with a continuous regenerative particulate trap and ultra-low-sulfur diesel fuel (less than 5 ppm). The demonstrator boasted particulate matter emissions reduction of more than 90%, which is within the EPA's proposed Tier 2 limits. Its particulate emissions are 50% lower than the best 1998-certified compressed natural gas engine. Hydrocarbons were reduced below measurable levels, which eliminated the odor often associated with diesel engines.
Navistar has established a joint venture with Siemens Automotive Corp. in developing a crucial element of the technology - next-generation diesel fuel injectors. The JV will incorporate proprietary digital valve technology under license from Sturman Engine Systems, LLC.
Siemens Automotive owns 51% of the nearly $100 million joint venture, which will operate as Siemens Diesel Systems Technology, LLC. The partnership is expected to produce up to 4 million injectors per year by 2005. The joint venture will manufacture the low-pressure, common-rail, digital-valve fuel injectors at Navistar's Engine and Foundry Division facility in Richland County, SC. To bring the new technology to the North American market as quickly as possible, the joint venture will temporarily locate in an existing 6500-m2 (70,000-ft2) facility in Columbia, SC, until a new facility can be built. The operation will create up to 500 new jobs by October of 2004.
Navistar is contributing expertise for the electrohydraulic system and its applications in engines and vehicles. Siemens Automotive brings its fuel delivery technology and high-volume manufacturing capability. The electronically controlled, hydraulically actuated low-pressure injectors and Green Diesel Technology are scheduled to be ready for commercial use by the 2002 model year. The new technology, which is intended for heavy, medium, and light diesel engine applications, will first be used in Navistar's International brand trucks and buses as well as products of other major Navistar customers in both North and South America.
