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Viewing 70801 to 70830 of 109901
1991-09-01
Technical Paper
911906
Tor Larsson, Kjell ac Bergstrom, Ake Bengtsson, John Petersson, Ingemar Denbratt
During 1991 Volvo Car Corporation has introduced the new Volvo 850 GLT model featuring front wheel drive with transverse installation of the engine and gearbox. The powertrain; consists of a new in-line five-cylinder engine in combination with a four speed electronically controlled automatic gearbox or a five speed manual gearbox. The engine features DOHC 20 valves, V-VIS (Volvo Variable Induction System), well tuned exhaust system and microprocessor controlled engine management systems. The engine was designed and developed as a new member of Volvo's modular engine family. The first member was the in-line six-cylinder engine B6304F [1] introduced in 1990. The modular engines have a large number of identical components and the major components are machined in common transfer lines which makes the manufacturing process highly rational and cost-effective.
1991-09-01
Technical Paper
911908
Hirokazu Nakamura, Hikoichi Motoyama, Yuhiko Kiyota
During next decade, automotive engineers will take up unprecedented challenges to meet a variety of technical demands on passenger cars. While performance, refinement and reliability will continue to be major technical goals of passenger cars, reducing their impact on the environment not only in urban areas but also on the global basis will become an increasingly urgent issue. In addition, the need for energy and resources saving will necessitate development of more fuel efficient cars, exploitation of alternative energy and recycled materials. In this paper, the authors will review various alternative engines as candidates to satisfy the above demands. The authors will also discuss various alternative transportation energy sources such as alcoholic fuels, natural gas, hydrogen and electricity. Finally the trends of future passenger car engine design will be discussed.
1991-09-01
Technical Paper
911901
Toshikazu Murakami, Kunio Yamada, Katsujiro Tachikawa
This paper presents a technique to predict the suspension load in early design stage when a passenger car with low profile tires goes over a bump. The suspension load is simulated by using ADAHS (Automatic Dynamic Analysis of Mechanical Systems). The tire was modeled as a radial spring with non-linearity decided by test data. The simulated results of suspension load agreed with the test data. The effect of shock absorber characteristics and spring bumper stiffness on the suspension load was studied by using this simulation model. As a result, the optimum specification for suspension load reduction was taken.
1991-09-01
Technical Paper
911884
Dennis Kemper
Abstract Hoses and assembies used in hydraulic applications are constantly being required to do more and more. The hydrostatic drives are becoming more sensitive to dirt and contamination. In addition, new hydraulic fluids are now being introduced that are more environmentally, safe. As a result, care must be taken in choosing the materials used and the processes of manufacturing in order to ensure that the assemblies provide long life and will not contribute to system failures.
1991-09-01
Technical Paper
911868
Yang-Zeng Xu, Gen-Xi Li
It is still a new technique to produce series of hydraulic radial piston pump using integrated CAD/CAM technique. That is, a hydraulic pump could be produced according to the required NC format program in NC machine tool (NC post-processing). The program is automatically generalized after the design stage in a RPCADM package is over. The one of the highlights to use the integrated CAD/CAM technique is how to use the similitude theory as basic principles for the series design in the CAD stage. Another is the method of transferring detail drawing into required G-codes based on the G-codes bank which NC machine tools could follow to produce the part. The theory and method are explicated in this paper. And the NC format program (G-codes file) conducted from CAD is shown. A package for CAD/CAM of hydraulic radial piston pump is introduced briefly.
1991-09-01
Technical Paper
911875
Atul B. Patil
Computer Simulation of ride dynamics of a two-wheeled scooter is carried out to seek directions of improvement in design of its suspension. The paper deals with the study of a scooter adopting link type suspension both in front and rear. A five degree freedom planar model for a two wheeler is developed. It includes geometric nonlinearities due to linkage assembly in front and rear suspension, multi rate springs, shock absorber nonlinearity, suspension bottoming and wheel lift off. A good correlation was observed between the simulated and experimental results. It is shown here how adjustment in damping coefficients of the shock absorber improves the passenger comfort while passing over a road bump.
1991-09-01
Technical Paper
911866
Max P. Gassman
Abstract Mechanical linkages are often used with fluid power systems to produce desired operations or work. Linkages may be used in hydromechanical servomechanisms or as actuator powered machine members. Many examples can be found of linkages associated with fluid power systems, on construction and agricultural machinery. The reaction of linkage members to fluid actuator motion is of considerable interest to machine designers. This paper describes a method of using loop closure equations, from kinematics, to model and analize linkages configured with fluid power machinery.
1991-09-01
Technical Paper
911848
Kazuo Sato, Haruo Ukawa, Masamitsu Nakano
This paper deals with a successful attempt to employ the exhaust gases of a two-stroke cycle gasoline engine as an energy source to operate an after burner and a Stirling engine, and to clean the exhaust gases by a catalyzer. By means of a rotary valve and the exhaust pipe sections, the exhaust gases could separated into a high concentration of fresh gas and a high concentration of combustion gas. The former gas was burned by a burner, and then used to heat a Stirling engine. The latter gas was disposed of by an oxidation catalyzer. The investigation revealed the enthalpy and exergy flows of a two-stroke cycle gasoline engine, a burner, a catalyzer and a Stirling engine, and then the emission gases (HC, CO, NO) were disposed of by the burner and catalyzer. The investigative analysis shows a method of successfully transferring the energy available in the exhaust gases for the combustion of a burner and the operation of a Stirling engine, a burner and a catalyzer.
1991-09-01
Technical Paper
911867
Xiaoqing Zhang, John K. Schueller, Herman Lam
Abstract Issues concerning the use of object-oriented knowledgebases in hydraulic circuit design are discussed. Hydraulic system knowledge representation is described with a semantic association model. Hydraulic circuit design rules are categorized and modeled as integrity constraint or deductive rules. This work demonstrates that an object-oriented knowledgebase could potentially be a viable tool for providing the hydraulic circuit designer with an evaluation of the designed circuit. The techniques need further development to be useful by the practicing designer.
1991-09-01
Technical Paper
911992
Fred Aboosaidi, Matthew J. Warfield, Dipankar Choudhury
Two three-dimensional cabin airflow configurations have been the subject of experimental and analytical testing to establish the validity and role of computational fluid dynamics (CFD) tools in the design of cabin airflow distribution systems. The CFD tools considered here are two separate Navier-Stokes computer codes which have been used for a number of applications, including those in the present study. A correlative study of a detailed air supply nozzle configuration has been examined to further understand its flow characteristics and to establish a procedure for examining cases with large size scale differences. The comparison of experimental results with the numerical simulations in the two cases is generally quite good, leading to an increased confidence in the application of CFD methods within the cabin airflow distribution system design arena.
1991-09-01
Technical Paper
911865
C. R. Burrows, S. P. Tomlinson, P. A. Hogan
1991-09-01
Technical Paper
911990
P. Raj, S.W. Singer
Computational aerodynamics offers one of the most promising means of improving the productivity of the aircraft design process. Evaluation of numerous geometric modifications in a typical design cycle is very costly and time consuming if done using wind tunnels alone. The potential-flow computational methods can provide reliable aerodynamic data needed for aircraft design as long as the flow is entirely subsonic or supersonic and remains attached. Methods based on the Euler and Navier-Stokes equations do not suffer from such restrictions and are, therefore, capable of providing aerodynamic data for a much wider range of flow conditions. Such capabilities are illustrated in this paper. Solutions obtained using a state-of-the-art Three-dimensional Euler/Navier-Stokes Aerodynamic Method, TEAM, are presented for four test cases ranging from an airfoil to the complete advanced tactical fighter prototype configuration.
1991-09-01
Technical Paper
911989
Ronald L. Bengelink, Paul E. Rubbert
CFD now stands alongside the wind tunnel in terms of importance to aerodynamic design. Its usage by engineering designers involves many thousands of runs per year, and the rate is increasing. For the simpler aerodynamic flows where viscous effects are modest, CFD has become the dominant tool for aerodynamic design. The primary role of the wind tunnel for such flows is for validation of a design and for determination of aerodynamic characteristics over the broad flight envelope. For more complex flows that are dominated by strong viscous effects, CFD is beginning to make a contribution. It is thought by many that the principle challenge for the future is to develop better computers and algorithms in order to better address the computation of complex flows over complex airplane geometries. But recent experiences involving the application of CFD to the design of the new Boeing 777 airplane has taught us that the challenge for the future is really much broader.
1991-09-01
Technical Paper
911984
Zhang Fu-Ze
This paper considers that fatigue scatter factors can be devided into the scatter factors for fatigue testing and those for theoretical computation. Both kinds can also be devided into the scatter factors for crack initiation lives and those for crack growth lives. This paper also studies the values of different kinds of scatter factors, and gives out suitable ones. Meanwhile, it makes comments on the calculation formulas and different values of scatter factors used by other countries. Through the study of the definitions and their parameter distributions of scatter factors and reductions factors, the author considers that it is possible to calculate them by a unified formula.
1991-09-01
Technical Paper
911981
Yoshito Miyamoto, Toshimi Fujita, Akihito Iwasaki, Hirotoshi Fujieda
As for a fully reusable space transportation system of a single stage to orbit(SSTO) of horizontal take-off and landing type, experimental studies on low-speed aerodynamic characteristics have been done. The wind tunnel tests were conducted using NAL's gust wind tunnel. Six-component force and moment data were obtained over an angle of attack range from -14° to 44°. In this paper, the aerodynamic test results are presented for the low-speed aerodynamics of a generic SSTO configuration.
1991-09-01
Technical Paper
911974
Evan A. Fradenburgh
This paper reviews the problems associated with developing a vertical takeoff and landing (VTOL) aircraft that has desirable helicopter-like attributes in hover and low speed operation but is capable of efficient high subsonic cruise speed. A number of different configurations that have been proposed are reviewed and an assessment is made of the relative probabilities of future success. Factors considered to be important discriminators include speed potential, disk loading, empty weight fraction, the need for supplementary propulsion systems or convertible engines, and technical risk. The tilt-rotor configuration has considerable merit but will not achieve the highest speeds desired. It is concluded that incorporation of variable geometry, in the form of a variable diameter rotor system, has the best chance of providing the “ideal” VTOL.
1991-09-01
Technical Paper
911969
Robert R. Barthelemy
1991-09-01
Technical Paper
911967
Leonard R. Tavernetti
Three SAE technical papers in recent years have addressed the C-17 program: “C-17 Technical Description” by Robert van't Riet, presented 8 March 1989, and “C-17 Flight Control System” by Alex Brown, and “Meeting the C-17 Reverse Thrust Requirements” by Frank Junkermann, both presented 3 October 1988. This paper provides an update of these previous presentations by members of the McDonnell Douglas C-17 team. The paper discusses technology adapted from commercial aircraft for military airlift; the military requirement to move large cargo items long distances and land on short runways, which drove C-17 design; and significant design alternatives and the solutions selected.
1991-09-01
Technical Paper
911949
Akihiro Masda, Masao Igarashi
Recently, air bag systems have been widely installed in cars. In the wiring harnesses of the air bagsystem, qualified processing, process record-keeping and process control are required to record high reliability and quality. In this regard, a process record-keeping and retrieval system has been developed. This system consists of 16 data terminals with handheld bar code scanners, 5 automatic bar code scanners and a personal computer with opto-magnetic disk as the server. These resources are networked by 1M bps Star-LAN. Software for LAN communication, data logging and retrieval is developed as a quasi-concurrent system on MS-DOS* environment avoiding the collision of data on LAN. In combination of a relational database on opto-magnetic disk, a process data retieval in 20 minutes has been proved among the data storage of 1M Byte per day, in 15 years, 4G Byte in total.
1991-09-01
Technical Paper
911945
Frank H. Johnson, Robert R. Wright, Thomas G. Carpenter, Randy Nelson
As reported by Wright and Carpenter (1) and others, the number of accidents resulting in serious injuries and deaths associated with All Terrain Vehicle (ATV) use increased dramatically during the 1980s. It was decided that a safer, more stable ATV should be and could be built. Three-wheel and four-wheel ATVs were considered. Two three-wheel ATVs and a four-wheel ATV were modified and fabricated as prototypes. While improvements of the three-wheel ATVs were realized, there were still considerable stability problems that could not be sufficiently corrected. The four-wheel prototype, denoted as RCX 250 (roll cage experimental vehicle with a 250 cc engine), demonstrated feasibility with clear improvements in safety. Analysis of the dynamics of the RCX 250 along with the description of the features and the test results are discussed.
1991-09-01
Technical Paper
911832
Keith Williams
Digital Electronics, Sensors, and Electro-hydraulic Control Valves have been combined to produce a system which automatically coordinates the variable reach boom on rough terrain forklifts to produce true Horizontal or Vertical Motion of the forks. The system results in fast and safe load placement and removal of forks from loads in high places with ease. Motion can be commanded by the operator to be horizontal or vertical. Boom Length sensors and Boom Angle sensors provide information to the micro-controller in order to control the motion of the boom which results in the desired horizontal or vertical motion regardless of slope of the terrain on which the vehicle is placed. Input of Engine Speed also ensures that the maximum flow commanded from the valves does not exceed flow available from the hydraulic pump resulting in smooth and fast coordinated boom motion at any engine speed. This paper describes the control system including the sensors, command joystick, and controller.
1991-09-01
Technical Paper
911846
Patrick J. Suhy, Lawrence W. Evers, Edward J. Morgan, Julie E. Wank
The feasibility of using kerosene fuel in a spark ignited two-stroke engine was investigated. Primary effort was directed at comparing kerosene fueled performance to gasoline fueled performance and to overcoming cold starting problems with kerosene. The single cylinder research engine had fuel injection upstream of the reed valve and used loop scavenging. A vortex pneumatic atomizer was used to reduced the droplet size. The results of this study indicate that the vortex pneumatic atomizer helps reduce poor performance of the engine when using kerosene fuel. A method to overcome the cold starting problem with kerosene fuel has been developed, which involves heating the atomization air during start up.
1991-09-01
Technical Paper
911834
James Kunz
In February of 1987, Dresser introduced a pair of new mechanical drive, off-highway trucks designed to operate in the 35 to 60 ton, rear-dump, classes. These trucks, designated 140M and 210M, replaced three previous models while covering the same payload range. One distinctive feature of these new vehicles was their hydraulic system and in particular the brake control portion of this system. This new hydraulic brake control system can be described as a closed-center arrangement using a pressure-compensated, variable displacement pump as an energy source with accumulator-based energy reserves for independent and redundant circuits. In the basic version, a pair of pressure regulating valves are used to control system pressure at the brakes. These valves can be actuated in tandem by a treadle (foot pedal) or separately by hydraulic pilot pressure. A single, filtered hydraulic fluid is used throughout the system and is stored in a single reservoir vented to atmosphere.
1991-09-01
Technical Paper
911815
P. Cui, R.T. Burton, P.R. Ukrainetz
The direct interface of fluid power components to digital computers requires electrohydraulic devices which can be actuated by a digital signal. High speed solenoid valves are devices ideally suited for this kind of application due to their on/off characteristics. In the last two decades, considerable research has been focused on developing fast responding on/off valves and this research has achieved some success. The fastest responding valves that have been reported are usually single stage and can only handle low flow rates. Two stage valves which can accommodate high flow rates have been developed, but they are either slow in responding or complicated in construction. In this paper, the feasibility of a rotary based, single stage, fast responding digital valve is considered. The feasibility study consisted of developing a nonlinear model of the valve from which transient and steady state responses were simulated.
1991-09-01
Technical Paper
911814
W. Backé, B. Zãhe
Valve-controlled hydraulic drives are frequently used when high dynamics, high reliability and a compact structural form are required. A disadvantage which is frequently attributed to a valve-controlled drive is its poor running efficiency. It not only leads to higher energy consumption but - amongst other things - to the necessity of installing larger pumps and more elaborate cooling equipment. Both these factors cause an increase in the costs of hydraulic drives. Load sensing is known from the field of mobile hydraulics as a driving concept with high running efficiency. In load sensing the supply pressure is adjusted to suit the actuator's highest point of load pressure. The dynamics of this system is worse than that of systems with a constant supply pressure. Electrohydraulic load sensing offers possibilities to improve the dynamics of valve-controlled drives in load sensing by using control engineering measures.
1991-09-01
Technical Paper
911808
Peter J. H. Treiber, Jaime E. Sauerteig
The development of European emission regulations for automotive heavy-duty Diesel engines began in the mid 1970s; the latest modifications to test procedures and standards have been in place since 1988. Presently, the emphasis of the European regulatory activities is in the areas of increasing the stringency of the gaseous standards and developing particulate standards. For non-automotive industrial engines, test procedures and standards are presently under consideration. Implementation of these requirements is anticipated in a two-stage approach beginning in the mid 1990s. This paper provides an overview of the present and future European exhaust emission requirements.
1991-09-01
Technical Paper
911816
Xin Fu Lu, Richard T. Burton, Greg J. Schoenau, X.R. Zeng
The problem of synchronizing several loads has been the subject of many studies over the past few years. Some of the authors have been involved in the design of high precision flow divider/combiner valves which are accurate to 99% over large pressure and flow ranges. The disadvantage of these designs lies in their inflexibility in terms of varying flow with complete independence to the various loads. Traditional approaches to the multi-load problem have been to use velocity or flow feedback signals to several electrohydraulic valves to obtain independent action. In this paper, the authors introduce the feasibility of using a single rotary type valve to provide a pulse width modulated flow pulse to each circuit. A model of the basic concept was used to establish the feasibility of the approach using simulation studies. A possible valve configuration to implement the concept is presented.
1991-09-01
Technical Paper
911807
Jeff J. White, James N. Carroll, Charles T. Hare, Jacline G. Lourenco
Recent approval of emission standards for small utility engines by the California Air Resources Board(1)* suggests that substantial reductions in emissions from small utility engines will soon be required. While 1994 standards may be met with simple engine adjustments or modifications, 1999 standards are much more stringent and may require the use of catalysts in conjunction with other emission reduction technologies. Assessing the feasibility of candidate emission control strategies is an important first step. Various emission reduction technologies were applied to three different 4-stroke engines. Emission tests were conducted to determine the effectiveness of air/fuel ratio changes, thermal oxidation, exhaust gas recirculation, and catalytic oxidation with and without supplemental air. Results of these evaluations, along with implications for further work, are presented. One engine's emissions were reduced below the levels of 1999 ARB standards.
1991-09-01
Technical Paper
911813
Larry L. Hartter, James A. Kessler, Richard S. Leemhuis, Velliyiur Subbarao
This paper describes a microcomputer-controlled hydraulic actuator designed with controllability, flexibility and ease-of-use as the fundamental goals. To achieve this, the electronics, valving, sensors and hydraulic cylinder are contained in a single, pre-engineered package. The embedded electronics provide complete closed-loop control of the actuator, including self-diagnostic capability and nonvolatile storage of application specific motion programs. Multiple actuators can be controlled via a serial communications bus to execute coordinated motions, or individual actuators can operate as stand-alone devices with simple on-off inputs to control their motion. This self-contained motion control package is well suited for the new generation of increasingly automated mobile machinery.
1991-09-01
Technical Paper
911763
Kenneth G. Weddfelt, Maria E. Pettersson, Jan-Ove S. Palmberg
Abstract Noise emission is often considered to be one of the major drawbacks of fluid power systems. One of the main sources of noise is flow ripple generated by positive displacement pumps. This paper is concerned with the problems of modelling and measurement of flow ripple with emphasis on measurement techniques. Measurements are performed according to the so-called “Two-Microphone Method”. This technique makes it possible to determine the source characteristics of the pump, i.e. both the source flow and source impedance. The technique is described in detail. Measurements have been performed on a piston pump equipped with a number of different port plate geometries. Experimental results are compared with results obtained from numerical simulation.