安全气囊技术简介

20 DECEMBER 2004 aei An electrohydraulic brake (EHB) system that monitors and controls every braking maneuver electronically on the world’s fi rst production-released full hybrid-elec- tric sport utility vehicle is the culmination of a jointly developed product. Continental Teves “wrote the sys- tem’s algorithm and software code. Ford Motor Co. provided the system require- ments and specifi cations” for the EHB system on the Escape Hybrid, according to Craig Belevender, Director of Brake Systems Engineering for Continental Teves North America. The software of the hybrid vehicle braking system controls the distribution between hydraulic brake force and electrical regenerative braking. “Sensors measure the motion and driver’s force on the brake pedal and transmit that data to the control unit. A computer calculates the optimum hydrau- lic pressure for each wheel and applies exactly the amount of braking force needed,” Belevender said. The system comprises a hydraulic elec- tronic control unit (HECU) that contains an electronic control unit, hydraulics, and high-pressure accumulator as well as an actuation control unit (ACU) that contains a brake fl uid reservoir, pedal feel emula- tor, and pedal travel sensor to measure the driver’s brake request. Continental Teves supplies the complete EHB system, including HECU, ACU, brackets, and g-force sensor to measure horizontal de- celeration during a vehicle stop. During a normal braking event, series regeneration occurs, meaning the hy- draulic and electrical regenerative braking modes are working simultaneously. As the vehicle is being driven, the brake module receives a signal from the power- train indicating how much regenerative torque or brake force is available from the powertrain. “When the driver applies the brake, our system utilizes the regenerative torque that is available from the power- train fi rst. If the driver’s request exceeds the amount of torque the powertrain can deliver, the brake system will then supple- ment it with friction brakes from the hy- draulic system or EHB,” said Belevender. The EHB system is sometimes referred to as a ‘wet’ brake-by-wire system. “The ‘wet’ means that the EHB system uses a hydraulic brake fl uid under pressure to supply the braking power,” said Belevender, adding, “The ‘by-wire’ means that the driver does not directly build pressure in the system and that there is a pedal travel sensor that measures the driver’s brake request.” Continental Teves is working on a next-generation braking system for hybrid vehicles. “It is under development cur- rently, and we are unable to provide fur- ther detail at this time,” said Belevender. Kami Buchholz Escape Hybrid’s stopping technology Approximately 100 inventions relating to the electrohydraulic brake technology (system schematic shown) have patents issued or pending. The Ford Escape Hybrid uses a Continental Teves EHB system. 412tbda.indd 20412tbda.indd 20 11/19/04 9:21:16 AM11/19/04 9:21:16 AM 22 DECEMBER 2004 aei Briefs The new CXT pickup truck from International Truck will ride on Goodyear commercial truck tires. The world’s largest production pickup truck has 22.5-in wheels with Unisteel G159A rib radial tires in the front and G167A drive-wheel radials in the rear. Power from the International DT 466 diesel en- gine is delivered through an Allison 2000 Series automatic transmission. ArvinMeritor has been awarded the de- sign and engineering of the exhaust and manifold for the successor to the X5 from BMW. The new vehicle will be built in Spartanburg, SC, with production begin- ning in October 2006. Aston Martin has selected the TPMS (tire pressure monitoring system) from SmarTire Systems for the DB9. The sys- tem was fi rst selected for the V12 Vanquish. A SmarTire TPMS monitors all tires independently, ensuring they are properly infl ated and running optimally. If an air pressure or temperature problem occurs, the driver is immediately alerted. The new 612 Scaglietti from Ferrari fea- tures Delphi’s advanced climate control technology. The car’s dual-zone system features automatic individually controlled front and rear controls to allow every oc- cupant the same level of thermal com- fort. A variable-displacement compressor at the heart of the air conditioning sys- tem automatically adjusts capacity to meet demand. Delphi also has full electri- cal systems responsibility for the vehicle. MAGNA Drivetrain, an operating group of Magna International, is supplying the integrated transfer case (ITC) for the new Land Rover Discovery III. The ITC provides permanent all-wheel drive with constant torque distribution, and is a key component of Land Rover’s Terrain Response system. GKN Driveline has introduced a new range of all-wheel-drive technology for small and midsize vehicles that was intro- duced in the Fiat Panda 4x4. GKN will supply all the components in partnership with Getrag for the power transfer unit and Dana for the rear differential. Quick change Four transmission downshifts within 1 s and individual gearshifts in less than 40 ms are being achieved by a new all-electric gearshift system, according to the com- pany that developed it, motorsports engi- neering specialist Zytek Systems. The technology is called EGS (electrically as- sisted gearshift system), and is said to be lighter and less complex than alternative hydraulic or pneumatic systems. the precise movement of its electric actua- tors means that there is very little wear on the gear selector mechanism and dog rings, helping extend gearbox life while improving reliability and shift accuracy. The EGS operates using fast-acting so- lenoids. A double-acting solenoid actuates the gearshift (twin single actuators can be used if required), with a single-acting sole- noid providing a throttle “blip” function. Driver control is via steering-wheel-mount- ed shift paddles, with separate push but- tons to select reverse and neutral. Clutch operation is just needed for step-off, re- verse, and neutral. The control unit of the EGS includes built-in energy storage; it accumulates electrical energy from the vehicle’s alterna- tor between gearshifts and delivers high power extremely rapidly for a fast shifting action. Zytek developed all the compo- nents and the control and calibration soft- ware. The control system interfaces directly with both Zytek and third-party engine controllers using either hard wiring or a CAN interface. The unit also interfaces with steering wheel instrumentation. Stuart Birch Zytek’s electrically assisted Gearshift System can make four downshifts in less than one second. It’s in the bag Because of the potential interaction be- tween infl ating airbags and small or out- of-position passengers during vehicle crashes, NHTSA has proposed and imple- mented revisions to the crash protection regulations that call for automakers to install advanced airbag deployment tech- nology. These revisions are to improve airbag restraint performance for a wider range of occupants and crash conditions. The regulations allow for the suppres- sion of airbag systems for small-stature occupants, as well as “low-risk” deploy- ment in which the airbag is deployed but the interaction between the occupant and the airbag is reduced. This legislation was Zytek’s Chief Engineer, Aidan Gregory, states that electric power is the ideal solu- tion to the challenge of achieving fast, reliable gearshifts in race conditions. “But the need for sophisticated energy man- agement and delivery has proved a barrier to implementation in the past. Now we have been able to apply knowledge gained from our electric-vehicle programs to make a robust, fl exible, and easily inte- grated solution.” Zytek—which has long-established ex- pertise in control electronics and software, together with electromechanical design specialization in electric vehicles—claims the EGS, which has a mass of about 3 kg (6.6 lb), removes the need for a separate hydraulic or pneumatic system, thus reduc- ing mass and complexity. It also states that 412tbda.indd 22412tbda.indd 22 11/19/04 9:21:29 AM11/19/04 9:21:29 AM 24 DECEMBER 2004 aei enacted in June 2000 for implementation beginning with 2004 model year vehicles. During this time, Key Safety Systems, a supplier of safety-critical components and systems including airbags, seatbelts, and steering wheels, began looking at new methods of low-risk airbag deploy- ment. Low-risk deployment can provide for improved real-world occupant safety, since the small-in-stature or out-of-posi- tion occupant will still receive some level of restraint, whereas the airbag is not de- ployed at all with a suppression system. The traditional approach for airbag suppression is to install an occupant clas- sifi cation system consisting of a pressure mat in the front passenger seat and sen- sors in the seat track and/or seatbelt mechanism to gather occupant data— whether the occupant is large or small, or out of position—for optimum cushion in- fl ation. The data, in addition to the crash speed, is then used to adjust the response of the airbag, typically to one of three al- ternatives: no deployment, de-powered deployment, or full deployment. The Key team developed instead a unique, active low-risk deployment tech- nology called the TickerTape Airbag (TTAB), which gathers the required infor- mation during the infl ation process and responds with an infi nitely tailorable air- bag deployment. Much of the time spent validating this concept was spent on tim- ing and size—whether an array of sen- sors, electronic algorithms, software, and mechanical hardware could indeed pre- vent airbag injury in the time it takes for an airbag to begin infl ating, and do so within the fi nite packaging limitations of a standard passenger airbag. Several software algorithm modules were developed for detecting injury mode data during critical infl ation stages, such as initial occupant interaction (when the bag fi rst deploys) and membrane loading (when the bag meets the resistance of the seated occupant). The algorithm recognizes the velocity pattern for an out-of-position occu- pant, interpreting size, position, and speed of movement, then sends an actuating sig- nal to a gas venting system. An innovative sensing technology was conceived by Key’s European engineering division and perfected by a multi-disciplin- ary team in the U.S. The sensing system consists of multiple strands of specially coded sensor tape—resembling stock- market ticker tape—sewn to strategic points on the inside of the front surface of the passenger airbag cushion. In a crash, the tapes are pulled through an optical sensing unit that reads velocity and interprets critical data about the crash incident and the interaction of the airbag with the passenger. The module then dy- namically assesses the correct amount of cushion for optimal passenger protection. This process occurs in less than 10 ms. A pyrotechnic venting device controls the amount of gas that fl ows into the cushion. Once enough gas has entered the cushion as determined by the software, an actua- tion signal opens a vent fl ap that directs the remainder of the infl ation gas outside the airbag module. Properly seated occupants receive a fully infl ated cushion, while the infl ation is proportionately reduced for smaller or out- of-position passengers by venting gas at a predetermined time depending upon seat- ing position. In recent crash tests, the TTAB system not only met but exceeded the NHTSA airbag safety requirements. Injury risk val- ues recorded by dummies representing young children without seatbelts with the system in use amounted to less than half those recorded during baseline testing conducted with the TTAB system disen- gaged. Small infant dummies secured in child seats sustained less than 10% of the baseline injury values. Since the TTAB system does not de- pend on seat occupant classifi cation sen- sors or mats to determine the required airbag performance, carmakers can reduce or eliminate them altogether to save cost. TTAB system components can be con- fi gured into a packaging size that con- forms to current production modules, con- solidating the electronic circuitry, airbag cushion, and hardware components with- out compromising performance. In addition to the increased safety ben- efi ts, the elimination of seat mats allows interior designers a wider selection of seat materials and the ability to use heated seats, while eliminating the need for in- strument panel warning lights that register seat mat sensor readings. The TTAB sys- tem is not susceptible to wear or abuse since all the components are contained within the passenger airbag module. Barrett Kalellis In a crash, the tapes in Key Safety Systems’ airbag are pulled through an optical sensing unit that reads the velocity and interprets critical data about the crash incident and the interaction of the airbag with the passenger. TickerTape Airbag components can be confi gured into a package that conforms to current production modules, consolidating the electronic circuitry, airbag cushion, and hardware components. Strip attachment Airbag Release mechanism Valve cover Sensing unit Data evaluation Infl ator Strip container 412tbda.indd 24412tbda.indd 24 11/19/04 9:21:37 AM11/19/04 9:21:37 AM 26 DECEMBER 2004 aei BorgWarner has begun production of the chain timing system for the “world engine,” a family of four-cylinder gasoline engines produced by the Global Engine Alliance. The Alliance, a joint venture between Hyundai, DaimlerChrysler, and Mitsubishi, was announced in May 2002. Total annual world-engine production is estimated at more than 1.6 million units, which would make it the highest- volume engine family in the world, ac- cording to BorgWarner. “BorgWarner’s globally integrated or- ganization allows us to provide our cus- tomers with local service in each of the world-engine production regions,” said BorgWarner Chairman and CEO Tim Manganello. “This capability is a consideration in many sourcing decisions today.” The world engine will be manufac- tured in production facilities located in BorgWarner technology links the world the U.S., South Korea, and Japan. Because the development costs are shared between fi ve operations in these three markets, the three OEMs anticipate signifi cant economies of scale. BorgWarner will supply the chain tim- ing system in all three markets. Vehicles equipped with these systems will benefi t from reduced engine noise and emissions, and increased performance and durability, according to the supplier. Production is currently being launched for the Korean market. In North America and Japan, pro- duction is expected to begin in mid-2005. In addition, BorgWarner will supply DaimlerChrysler with the electronic throt- tle control (ETC) for the North American version of the engine, which is produced in Dundee, MI. ETC provides unlimited calibration possibilities for improved driv- ability and fuel economy. Production is expected to begin in late 2005. Ryan Gehm BorgWarner is supplying the engine chain timing system for a family of four-cylinder gasoline engines produced by the Global Engine Alliance. The R&D race between diesel and gasoline engine technology continues apace. A new research program into achieving sig- nifi cant improvements in fuel consumption and a reduction in emissions of diesel en- gines has begun in the UK at the University of Bath’s Department of Mechanical Engineering. Ford is giving the program fi nancial support, together with the UK government via its Science Research Investment Fund. The program emphasis will be on mak- ing the temperature control and cooling system more effi cient, and increasing the number of components powered by elec- tricity. A major aim of the work is to help reduce diesel engine pollutants by half over the next seven years; the program will help Ford’s work with PSA Peugeot Citroën on advancing diesel engine technology. “This is not research that sits on a shelf gathering dust; our results will be in the cars people drive—cutting diesel bills and reducing waste products—within fi ve to ten years,” said Professor Gary Hawley, Head of the University of Bath’s Powertrain and Vehicle Research Unit, which is carry- ing out the work. The University is also looking farther ahead and considering other aspects of advancing vehicle technology. While 48-V systems are very much on hold due to cost and complexity issues and also to advanc- es made by 12-V systems, Hawley believes that in the next fi ve years, vehicle electrical systems will switch to 36-V. This would help facilitate stop-start technology and virtually eliminate pollution from standing traffi c. “Higher voltage would also allow wa- ter pumps and air conditioning to be com- pletely driven by electricity rather than me- chanically, and facilitate more elaborate entertainment and communications sys- tems,” added Hawley. “Catalytic convert- ers would benefi t from electrical heating.” Stuart Birch Research work at the University of Bath into signifi cantly reducing diesel engine fuel consumption and emissions is focused on making temperature control and the cooling system more effi cient while increasing the number of components powered by electricity. Cool diesel 412tbda.indd 26412tbda.indd 26 11/19/04 9:21:41 AM11/19/04 9:21:41 AM 28 DECEMBER 2004 aei Engineers, technicians, designers, pro- gram managers, and others said good- bye to Liberty and Technical Affairs—an advanced technology division of the Chrysler Group—when Liberty dissolved a few months ago. But for former Liberty staff, their creative contributions continue to shape personal transportation options via DaimlerChrysler product teams. Established in February 1989, the Liberty entourage worked to develop ad- vanced vehicle concepts and prototypes, commonly building demonstration prod- ucts to showcase potential production technologies. “Liberty had so much diversity—peo- ple in design, people in body/chassis, people in powertrain as well as materials and manufacturing experts—and having those people meant Liberty could produce vehicles with advanced Liberty endeavors live on concept sport utility vehicle and the 2001 Natrium minivan concept. F-Cell vehicles recently entered fl eet customer testing in the United States, Japan, Germany, and Singapore. “We’re gaining valuable information from having F-Cell vehicles in fl eet tests,” said Cherry, whose focus encompasses Michigan customers such as the United Parcel Service (UPS). “UPS drivers turn the vehicle ignition off and on at every delivery stop—maybe 100 or 200 times a day—and that start- ing and stopping represents an atypical driving cycle for a hydrogen fuel-cell ve- hicle. The ultimate software solution might be an adaptive driving cycle algo- rithm,” said Cherry. F-Cell vehicles represent just one on- going project with a Liberty tie-in. While the Liberty group name is defunct, the group’s staff continues in Advance Vehicle Engineering roles. “The previous Liberty organization provided underlying technology for many past concept vehicles. The new organiza- tion structure helps align the goals, initia- tives, and talents of all advance engineer- ing activities into one cohesive focus,” said Lou Rhodes, Director of Advance Vehicle Concepts and Innovation, an Advance Vehicle Engineering team that supports product creation of Chrysler Group vehicles. Kami Buchholz powertrains,” said Jeff Cherry, a former Liberty team member now working as a project engineer for fuel-cell programs