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Journal Article

Verification of Flag Usage Patterns by Static Analysis Techniques

2014-04-01
2014-01-0180
A flag is a global boolean variable used to achieve synchronization between various tasks of an embedded system. An application implementing flags performs actions or events based on the value of the flags. If flag variables are not implemented properly, certain synchronization related issues can arise which can lead to unexpected behavior or failure of the underlying system. In this paper, we present an automated verification technique to identify and verify flag usage patterns at an early stage of code development. We propose a two-step approach which consists of: a. identification of all potential flag variables and b. verification of flag usage patterns against predefined set of rules. The results of our experiment demonstrate that the proposed approach reduces the cost and complexity of the flag review process by almost 70%.
Technical Paper

The Development of a High Speed Steel Based Sintered Material for High Performance Exhaust Valve Seat Inserts

1998-02-23
980328
The demands on valve seat insert materials, in terms of providing greater wear-resistance at higher temperatures, enhanced machinability and using non-environmentally hazardous materials at a reasonably low cost have intensified in recent years. Due therefore to these strong demands in the market, research was made into the possibility of producing a new valve seat insert material. As a result a high speed steel based new improved material was developed, which satisfies the necessary required demands and the evaluation trials, using actual gasoline engine endurance tests, were found to be very successful.
Technical Paper

Technological Trends in Automotive Electronics

1987-11-08
871285
Although automotive electronics was initially applied as a substitute for mechanical parts, this technology has the potential to achieve effective combinations of mechanical functions. A case in point is the successful resolution of fuel consumption and exhaust emission problems by effectively integrating engine control and catalyst technologies. LSI technology has also been incorporated into automotive electronics and established as a fundamental engine control tool. Thanks to LSI technology, particularly the use of microprocessor techniques, conventional machine design problems have been transformed into logical design ones. In the next stage of application, automotive electronics is expected to provide further benefits including a more comfortable ride, an improved human-machine system interface, and an advanced communications system between vehicles and other telecommunications stations.
Technical Paper

Technique for Analyzing Swirl Injectors of Direct-Injection Gasoline Engines

2001-03-05
2001-01-0964
This paper describes the numerical and experimental approaches that were applied to study swirl injectors that are widely used in direct-injection gasoline engines. As the numerical approach, the fuel and air flow inside an injector was first analyzed by using a two-phase flow analysis method [VOF (Volume of Fluid) model]. A time-series analysis was made of the flow though the injector and also of the air cavity that forms at the nozzle and influences fuel atomization. The calculated results made clear the process from initial spray formation to liquid film formation. Spray droplet formation was then analyzed with the synthesized spheroid particle (SSP) method. As the experimental approach, in order to measure the cavity factor that represents the liquid film thickness, nozzle exit flow velocities were measured by particle image velocimetry (PIV).
Technical Paper

Swirling Flow Type Jet Pump for Transferring Fuel Inside Saddle-Shaped Fuel Tanks

1989-09-01
891960
This paper presents a swiring flow type jet pump which has been developed and in put into practical use in transferring fuel between sumps in saddle-shaped fuel tanks. The pump is driven by the force of excess fuel returning from the engine. The major structural features of the pump are described along with its performance. Various problems encountered in the process of developing the pump are discussed along with the technologies developed to resolve them. Particular attention is focused on the effects that the geometries if the nozzle, throat and swirling groove have on fuel transfer efficiency. The results of experiments carried out to analyze these correlations are also presented.
Technical Paper

Swirl Controlled 4-Valve Engine Improves in Combustion under Lean Air-Fuel Ratio

1987-11-08
871172
Since a 4-valve engine is less flexible in the design and location of the intake ports as compared with a conventional 2-valve engine, there are some difficulties in strengthening the air motion, including swirl and turbulence, in order to achieve stable combustion under lean mixture operation. This study examined air motion imporvements of 4-valve engine that result in a stable combustion with a lean mixture. These improvements are brought about by the installation of a swirl control valve in each intake port. The results of this study have clarified that the lean stable limit was extended from an air-fuel ratio of 21.5 to 26.3 under a partial load, by optimizing the location and diameter of aperture of the swirl control valve.
Technical Paper

Small Engine - Concept Emission Vehicles

1971-02-01
710296
Three Japanese automobile manufacturers-Mitsubishi Motors Corp., Nissan Motor Co., Ltd., and Toyo Kogyo Co., Ltd.-have been making efforts over the past three years to design and develop effective thermal reactor-exhaust gas recirculation and catalytic converter systems suitable for small engines. The work is being done by members participating in the IIEC (Inter-Industry Emission Control) Program, and the exhaust emission levels of the concept vehicles developed by these companies have met the goal established by the IIEC Program at low mileage. Each system, however, has a characteristic relationship between exhaust emission level and loss of fuel economy. Much investigation is required, particularly with respect to durability, before any system that will fully satisfy all service requirements can be completed. This paper reports the progress of research and development of the individual concept vehicles.
Technical Paper

Sinter Diffusion Bonded Idler Sprocket of Automotive Engine

1995-02-01
950390
The key-points in the diffusion bonding technique of green compacts during sintering, are the material compositions, which should be chosen according to their dimensional change during sintering, and the fitting clearance, which should be maintained in the range of press fit. Applying this technique, we have developed sinter-diffusion bonded idler sprockets for automotive engines by comfirming the bonding strength and torsional fatigue strength. And we also have developed a nondestructive analysis method for assuring the joint strength of idler sprockets in the mass production.
Technical Paper

Simultaneous Attainment of Low Fuel Consumption High Output Power and Low Exhaust Emissions in Direct Injection SI Engines

1998-02-01
980149
This paper describes simultaneous attainment in improving fuel consumption, output power and reducing HC emissions with a direct injection S.I. engine newly developed in Nissan. Straight intake port is adopted to increase discharge coefficient under WOT operation and horizontal swirl flow is generated by a swirl control valve to provide stable stratified charge combustion under part load conditions. As a result, fuel consumption is reduced by more than 20% and power output is improved by approximately 10%. Moreover, unburned HC is reduced by equivalently 30% in engine cold start condition. An application of diagnostic and numerical simulation tools to investigate and optimize various factors are also introduced.
Technical Paper

Simulation of Bearing Wear and Its Influence Upon Bearing Performance Based on Elastohydrodynamic Analysis

1999-05-03
1999-01-1522
This paper reports attempts to gain better understanding of the influence of bearing wear on the performance of hydrodynamically lubricated bearings. An analysis was carried out on bearings from a Sapphire bearing test rig using an elastohydrodynamic model. This involved the use of both the original and worn bearing surface profiles. The results indicated that bearing wear could improve the lubrication conditions. Also the progress of wear in the bearing was simulated using a simple model of the wear process. This model predicted that the wear would progress at a reducing rate. The predicted wear agreed well with measurements both in terms of the wear profile and the location of wear.
Technical Paper

Research on a Variable Swirl Intake Port for 4-Valve High-Speed DI Diesel Engines

1998-10-19
982680
A variable swirl intake port system for 4 valves/cylinder direct injection diesel engines was developed. This system combines two mutually independent intake ports, one of which is a helical port for generating an ultra-high swirl ratio and the other is a tangential port for generating a low swirl ratio. The tangential port incorporates a swirl control valve that controls the swirl ratio by varying the flow rate. To investigate the performance of the intake port system, steady-state flow tests were conducted in parallel with three-dimensional computations. In conducting the steady-state flow tests, it was found that a paddle wheel flow sensor was not suitable for evaluating the characteristics of the high-swirl port and that it was necessary to use an impulse swirl flow meter.
Technical Paper

Research on Crankshaft System Behavior Based on Coupled Crankshaft-Block Analysis

1997-10-01
972922
Achieving a multi-cylinder engine with excellent noise/vibration character sties and low friction at the main bearings requires an optimal design not only for the crankshaft construction but also for the bearing support system of the cylinder block. To accomplish that, it is necessary to understand crankshaft system behavior and the bearing load distribution for each of the main bearings. Crankshaft system behavior has traditionally been evaluated experimentally because of the difficulty in performing calculations to predict resonance behavior over the entire engine speed range. A coupled crankshaft-block analysis method has been developed to calculate crankshaft system behavior by treating vibration and lubrication in a systematic manner. This method has the feature that the coupled behavior of the crankshaft and the cylinder block is analyzed by means of main bearing lubrication calculations. This paper presents the results obtained with this method.
Technical Paper

Reduction of Transaxle Gear Noise by Gear Train Modification

1992-09-01
922108
As the quietness of vehicles has been continually improved in recent years, there have been stronger requirements to reduce transmission gear noise and thereby improve transmission quality. So far efforts to achieve quieter gears have generally focused on ways of reducing the excitation forces of individual gears. In addition to these traditional methods, there is a greater need today to adopt a new approach to gear noise reduction in which improvements are made to the gear train itself as the transmitter of vibration in the transmission. This paper describes the systematic approach taken to reduce the overall gear noise of the new RE4F04A four-speed automatic transaxle.The cross-sectional view is shown in Fig. 1. The vibration characteristics of this automatic transaxle were first identified by finite element analysis, and an investigation was made of a gear train structure that would be effective in reducing gear noise.
Technical Paper

Reciprocal Measurements of the Vehicle Transfer Function for Road Noise

2015-06-15
2015-01-2241
Road Noise is generated by the change of random displacement input inside the tire contact patch. Since the existing 3 or 6 directional electromagnetic shakers have a flat surface at the tire contact patch, these shakers cannot excite the vehicle in a manner representative of actual on-road road noise input. Therefore, this paper proposes a new experimental method to measure the road noise vehicle transfer function. This method is based on the reciprocity between the tire contact patch and the driver's ear location. The reaction force sensor of the tire contact patch is newly developed for the reciprocal loud speaker excitation at the passenger ear location. In addition, with this equipment, it is possible to extract the dominant structural mode shapes creating high sound pressure in the automotive interior acoustic field. This method is referred to as experimental structure mode participation to the noise of the acoustic field in the vibro-acoustic coupling analysis.
Technical Paper

Prediction of Crank Pin Journal Temperature Based on the Oil Flow Rate

1998-05-04
981403
Improving the durability and reliability of crankshaft bearings has become an important issue for automotive engines recently because of conflicting demands for lower fuel consumption and higher power output. This study focused on the connecting rod big-end bearing which is subjected to harsher operating conditions on account of these requirements. It is known that the crank pin journal temperature is an indicator of big-end bearing seizure. Having a simple method for predicting the crank pin journal temperature with the required accuracy at the design stage is indispensable to efficient engine development. In this study, analyses were first conducted to determine the oil flow rate at the big-end bearing which is a major determinant of the crank pin journal temperature.
Technical Paper

Nissan's Low-Noise Full-Scale Wind Tunnel

1987-02-01
870250
In October 1985, a new wind tunnel was completed and put into operation at the Nissan Technical Center. This paper describes its main specifications and performance features, and gives results of a number of experiments using the new facility. It is a closed-circuit wind tunnel of the so-called Göttingen type, with a semi-open test section. The test section is equipped with two different nozzles, which are used interchangeably depending on the type of testing being carried out. The larger nozzle has a maximum wind velocity of 190 kmh, and a cross-section 4 m high by 7 m wide. The other is 3 m high by 5 m wide and has a maximum wind velocity of 270 kmh. All of the testing equipment in the tunnel, including the axial-flow fan, six-component aerodynamic balance, and traverse system, are operated automatically by a control system made up of several computers linked together. The most notable feature of this wind tunnel is the large reduction that has been made in background noise.
Technical Paper

New PM Valve Seat Insert Materials for High Performance Engines

1992-02-01
920570
Internal combustion engines experience severe valve train wear and the reduction of valve seat and seat insert wear has been a long-standing issue. In this work, worn valve seats and inserts were examined to obtain a fundamental understanding of the wear mechanisms and the results were applied in developing new valve seat insert materials. The new exhaust valve insert material for gasoline engines is a sintered alloy steel containing Co-base hard particles, with lead infiltrated only for inserts used in unleaded gasoline engines. The new intake valve insert material for gasoline engines is a high-Mo sintered steel, obtained through transient liquid phase sintering and with copper precipitated uniformly. This material can be used for both leaded and unleaded gasoline engines. Valve and valve seat insert wear has long been an issue of concern to engine designers and manufacturers.
Technical Paper

New Copper Alloy Powder for Laser-Clad Valve Seat Used in Aluminum Cylinder Heads

2000-03-06
2000-01-0396
A copper alloy powder composed of Cu-14Ni-3Si-2V-2Cr-1.5Fe-1Al-0.5P has been developed for application to laser-clad valve seats. Laser-clad valve seats offer several advantages such as higher engine output and improved fuel economy owing to lower valve head temperature and an increased intake throat diameter compared with conventional press-fit valve inserts made of ferro-based powder metal. Previously, a material having a principal chemical composition of Cu-12Ni-10Co-3Si-2V-2Nb-1.5Fe-1Al was developed to obtain large hard intermetallic compounds. The microstructure of this material is formed by a two-liquid separation reaction, which has been applied to powders of different chemical compositions for laser-clad valve seats of production engines. Although this material shows superior valve seat wear resistance, it has certain drawbacks, including the high cost of the powder, high probability of microcrack formation and low machinability of the laser-clad layer.
Technical Paper

Joint PAJ/JAMA Project - Development of a JASO Gasoline Bench Engine Test for Measuring CCDs

1997-10-01
972837
Detergent additives in automotive gasoline fuel are mainly designed to reduce deposit formation on intake valves and fuel injectors, but it has been reported that some additives may contribute to CCD formation. Therefore, a standardized bench engine test method for CCDs needs to be developed in response to industry demands. Cooperative research between the Petroleum Association of Japan (PAJ) and the Japan Automobile Manufacturers Association, Inc. (JAMA), has led to the development of a 2.2L Honda engine dynamometer-based CCD test procedure to evaluate CCDs from fuel additives. Ten automobile manufacturers, nine petroleum companies and the Petroleum Energy Center joined the project, which underwent PAJ-JAMA round robin testing. This paper describes the CCD test development activities, which include the selection of an engine and the determination of the optimum test conditions and other test criteria.
Technical Paper

In-line Hydrocarbon (HC) Adsorber System for Reducing Cold-Start Emissions

2000-03-06
2000-01-0892
An adsorber system for reducing cold-start hydrocarbon (HC) emissions has been developed combining existing catalyst technologies with a zeolite-based HC adsorber. The series flow in-line concept offers a passive and simplified alternative to other technologies by incorporating one additional adsorber substrate into existing converters without any additional valving, purging lines, secondary air, or special substrates. Major technical issues to be resolved for practical use of this system are 1) the ability to adsorb a wide range of HC molecular sizes in the cold exhaust gas and 2) the temperature difference between HC desorption from the adsorber and activation of the catalyst to convert desorbed HCs. This paper describes the current development status of hydrocarbon adsorber aftertreatment technologies. We report results obtained with a variety of adsorber properties, washcoat structures of adsorber catalyst and start-up and underfloor catalyst system combinations.
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