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Technical Paper

Study on Practicality of Electric Vehicle “i-MiEV” under Severe Weather

2011-05-17
2011-39-7241
Mitsubishi Motors Corporation succeeded in mass production of the electric vehicle “i-MiEV” which features leading-edge technologies epitomized by lithium-ion battery. The EV was released into the Japanese market in July 2009 and the European market in January 2011. In order to be used all over the world, the EV has to be practical and durable even under severe weather of extremely cold or extremely hot regions. In this paper we report some results of the tests conducted under extremely cold weather as well as extremely hot weather. From the test results the validity of the vehicle control system and the practicality of the EV are verified.
Technical Paper

Interior Noise evaluation of Electric Vehicle: Noise source contribution analysis

2011-05-17
2011-39-7229
Global environment protection, Co2 emission reduction and so on, is an important problem in automotive industry. An Electric Vehicle (EV) production is one of policies. Co2 emission of EV is lower than Internal Combustion Engine (ICE), petrol and diesel engine. On the other hand, customer's needs for the comfort on driving increase year after year. So it's an important factor for new car performance. Generally speaking, it's thought that the noise and vibration performance of EV have the better of ICE performance. However the aerodynamic noise and road noise contribution for interior noise in EV rise in comparison with ICE, and moreover the sound quality change by new noise component of the motor noise. Therefore new sound evaluation method is needed for EV. So this paper demonstrates each noise component contribution in EV by new noise separation technology, and show the comparison result with EV and ICE.
Journal Article

Keys to Understanding Spray-guided Combustion of a Narrow-spacing Gasoline Direct Injection SI Engine with a Centrally Mounted Multi-hole Injector

2009-04-20
2009-01-1497
Spray-guided gasoline direct injection SI engines attract as one of new generation lean-burn engines to promise CO2 reduction. These typically adopt “narrow-spacing” concept in which an injector is centrally mounted close to a spark plug. Therefore, geometric targets of the fuel spray and a position of the spark plug have to be exactly limited to maintain a proper mixture in the spark gap. In addition, the stable combustion window is narrow because the spark ignition is limited in a short time during and immediately after the injection. These spatial and temporal restrictions involve some intractable problems concerning the combustion robustness due to the complicate phenomena around the spark plug. The local mixture preparation near the spark plug significantly depends on the spray-induced charge motion. The intense flow induced by the motion blows out and stretches the spark, thereby affecting the spark discharge performance.
Technical Paper

Effect of the Right-and-left Torque Vectoring System in Various Types of Drivetrain

2007-08-05
2007-01-3645
This paper describes the calculative verification of the effect of the right-and-left torque vectoring system in various types of drivetrain, namely, the front wheels only, the rear wheels only, and both front and rear wheels in FWD, RWD, and AWD vehicles. The effect is evaluated by calculating the vehicle dynamics limit; maximum acceleration and cornering ability. The right-and-left vectoring torque, which is needed for expanding the vehicle dynamics limit, is also calculated. And finally, the paper evaluates the suitable wheels for which the system should be applied in each drivetrain. The application to the front wheels is more effective for FWD vehicles. On the other hand, the application to the rear wheels is more effective for RWD and AWD vehicles.
Technical Paper

Mixing Control and Combustion in Gasoline Direct Injection Engines for Reducing Cold-Start Emissions

2001-03-05
2001-01-0550
A two-stage combustion is one of the Mitsubishi GDI™ technologies for a quick catalyst warm-up on a cold-start. However, when the combustion is continued for a long time, an increase in the fuel consumption is a considerable problem. To solve the problem, a stratified slight-lean combustion is newly introduced for utilization of catalysis. The stratified mixture with slightly lean overall air-fuel ratio is prepared by the late stage injection during the compression stroke. By optimizing an interval between the injection and the spark timing, the combustion simultaneously supplies substantial CO and surplus O2 to a catalyst while avoiding the soot generation and the fouling of a spark plug. The CO oxidation on the catalyst is utilized to reduce the cold-start emissions. Immediately after the cold-start, the catalyst is preheated for the minimum time to start the CO oxidation by using the two-stage combustion. Following that, the stratified slight-lean combustion is performed.
Technical Paper

Prediction of Occupant's Thermal Sensation under the Transient Environment in a Vehicle Compartment

2001-03-05
2001-01-0586
New numerical simulation system and experimental evaluation system has been developed to predict and evaluate occupant's thermal sensation in a passenger compartment in which environment is not steady and not uniform. Transitional effective temperature, which is new index of thermal sensation, is proposed and verified to correspond with subjects' thermal sensation votes. The simulation system has two advantage beside the prediction of thermal sensation; automatic generation of a computational model and coupling analysis of temperature including an analysis of temperature distribution inside a cabin, refrigerating cycle, solar radiation, and so on. It was verified that this system well predicts occupant's thermal sensation in a short time.
Technical Paper

Development of the NOx Adsorber Catalyst for Use with High-Temperature Condition

2001-03-05
2001-01-1298
NOx adsorber has already been used for the after-treatment system of series production vehicle installed with a lean burn or direct injection engine [1,2,3]. In order to improve NOx adsorbability at high temperatures, many researchers have recently been trying an addition of potassium (K) as well as other conventional NOx adsorbents. Potassium, however, reacts easily with the cordierite honeycomb substrate at high temperatures, and not only causes a loss in NOx adsorbability but also damages the substrate. Three new technologies have been proposed in consideration of the above circumstances. First, a new concept of K-capture is applied in washcoat design, mixed with zeolite, to improve thermal stability of K and to keep high NOx conversion efficiency, under high temperatures, of NOx adsorber catalyst. Second, another new technology, pre-coating silica over the boundary of a substrate and washcoat, is proposed to prevent the reaction between potassium and cordierite.
Technical Paper

Development of Advanced Emission-Control Technologies for Gasoline Direct-Injection Engines

2001-03-05
2001-01-0254
An extensive effort has been made, at Mitsubishi Motors, in the technology field of new catalysts and of the catalyst reaction control for the purpose of further improvement of the emission control with the GDI engines [1-2]. A new NOx-trap catalyst has been developed to satisfy the required higher catalyst performance under high-temperature condition. The new catalyst contains potassium (K) of excellent NOx-storage capacity under high-temperature region in the catalytic atmosphere, and to retain K stability zeolite is mixed in the catalyst layer as well as the substrate is coated with silica (SiO2). This new catalyst has been proven of the improved NOx conversion efficiency, and solved the long-pending problems particularly those experienced under high-temperature operation.
Technical Paper

New Quiescent Combustion System for Heavy–Duty Diesel Engines to Overcome Exhaust Emissions and Fuel Consumption Trade–Off

2000-06-19
2000-01-1811
In the next few years, the USA, EU, and Japan plan to introduce very stringent exhaust emissions regulations for heavy–duty diesel engines, in order to enhance the protection air quality. This builds upon the heavy–duty diesel engine exhaust emissions regulations already in effect. At the same time, improvement in fuel consumption of heavy–duty diesel engines will be very important for lowering vehicle operating costs, conserving fossil fuel resources, and reduction of CO2 (greenhouse gas) levels. This paper presents a detailed review of a quiescent combustion system for a heavy–duty diesel engine, which offers breakthrough performance in terms of the exhaust emissions – fuel consumption trade–off, compared with the more conventional swirl supported combustion system. This conclusion is supported by experimental results comparing quiescent and swirl supported versions of various combustion system configurations.
Technical Paper

Development of High Performance Heavy-Duty Diesel Engine Oil to Extend Oil Drain Intervals: 5W30 Fully Synthetic Oil Containing MoDTC

2000-06-19
2000-01-1992
In this study, the oxidation stability, soot dispersancy, antiwear performance, and friction-reducing capability of friction modifiers (FMs) were evaluated, and an SAE 5W-30 fully synthetic oil with MoDTC type FMs was developed for heavy-duty diesel engines. In several engine tests, it was confirmed that the developed oil can double the oil drain interval in comparison with API CD SAE 30, even when EGR is applied, and improves the fuel efficiency.
Technical Paper

Computational design of commercial vehicle for reconciling aerodynamics and engine cooling performance

2000-06-12
2000-05-0344
As the global environmental protection becomes the world consensus recently, the regulations of the fuel consumption and the exhaust gas have large effects on the performance and the fundamental structure of commercial vehicles. Especially the technology concerning "fluid" and "heat" has a close relationship with those issues. Owing to above circumstances, commercial vehicles such as large trucks and buses are forced to be designed near the limit of allowance. Furthermore, a rapid design is another requirement. However, though significant number of variations, i.e., cab configuration, wheel base, rear body configuration, engine specification, etc., are prepared, it is impossible to improve the performance of all those combinations by experiments which cost a lot. Accordingly, the quantitative prediction using computer will become indispensable at the beginning term of new car development.
Technical Paper

Innovative injection rate control with next-generation, common-rail fuel injection system

2000-06-12
2000-05-0061
Injection rate control is an important capability of the ideal injection system of the future. However, in a conventional Common-Rail System (CRS) the injection pressure is constant throughout the injection period, resulting in a nearly rectangular injection rate shape and offering no control of the injection rate. Thus, in order to realize injection rate control with a CRS, a "Next- generation Common-Rail System (NCRS)" was conceptualized, designed, and fabricated. The NCRS has two common rails, for low- and high-pressure fuel, and switches the fuel pressure supplied to the injector from the low- to the high- pressure rail during the injection period, resulting in control over the injection rate shape. The effects of injection rate shape on exhaust emissions and fuel consumption were investigated by applying this NCRS to a single- cylinder research engine.
Technical Paper

Common Rail Fuel Injection System for Improvement of Engine Performance on Heavy Duty Diesel Engine

1998-02-23
980806
With the intention of improving engine performance and emissions, the authors examined the influence of the method of initial fuel injection quantity reduction and of the injector configuration of a common rail fuel injection system on engine performance and exhaust emissions. Results showed that decreasing the nozzle hole diameter was an effective way to reduce the initial injection quantity without increasing black smoke. Compared to a three-way type injector, it was found that a two-way type injector can greatly reduce the amount of fuel leakage from the electromagnetic injector control valve and fuel consumption could be further improved by reduction of the driving loss. Furthermore, the increase of driving losses with higher injection pressure was small, and as a result, higher pressure injection was possible.
Technical Paper

Mixing Control Strategy for Engine Performance Improvement in a Gasoline Direct Injection Engine

1998-02-23
980158
Spray motion visualization, mixture strength measurement, flame spectral analyses and flame behavior observation were performed in order to elucidate the mixture preparation and the combustion processes in Mitsubishi GDI engine. The effects of in-cylinder flow called reverse tumble on the charge stratification were clarified. It preserves the mixture inside the spherical piston cavity, and extends the optimum injection timing range. Mixture strength at the spark plug and at the spark timing can be controlled by changing the injection timing. It was concluded that reverse tumble plays a significant role for extending the freedom of mixing. The characteristics of the stratified charge combustion were clarified through the flame radiation analyses. A first flame front with UV luminescence propagates rapidly and covers all over the combustion chamber at the early stage of combustion.
Technical Paper

Optimized Gasoline Direct Injection Engine for the European Market

1998-02-23
980150
GDI (Gasoline Direct Injection) engine adopting new combustion control technologies was developed and introduced into Japanese domestic market in August of 1996. In order to extend its application to the European market, various system modifications have been performed. Injectors are located with a smaller angle to the vertical line in order to improve the combustion stability in the higher speed range. A new combustion control method named “two-stage mixing” is adopted to suppress the knock in the low speed range. As a result of this new method, the compression ratio was increased up to 12.5 to 1 while increasing the low-end torque significantly. Taking the high sulfur gasoline in the European market into account, a selective reduction lean-NOx catalyst with improved NOx conversion efficiency was employed. A warm-up catalyst can not be used because the selective reduction lean NOx catalyst requires HC for the NOx reduction.
Technical Paper

New Mitsubishi V8 19-Liter Turbocharged and Intercooled Diesel Engine

1997-05-01
971673
Mitsubishi Motors Corporation (MMC) has developed a new V configured 8 cylinder turbocharged and intercooled diesel engine (8M22T1) for the heavy-duty truck market. The engine is one of the first in its class to feature a common rail fuel injection system. This advanced engine management system was selected to meet the challenges of ever tightening emission regulation, specifically in the areas of smoke and noise. The 8M22T1 embodies a number of design innovations which have resulted in significant improvements in performance, fuel economy, durability and reliability.
Technical Paper

Analysis of Vehicle Wind Throb Using CFD and Flow Visualization

1997-02-24
970407
Passenger cars with sunroofs sometimes experience a low frequency pulsation noise called “wind throb” when traveling with the roof open. This “wind throb” should be suppressed because it is an unpleasant noise which can adversely affect the acoustic environment inside a car. In this paper, 3-dimensional numerical flow analysis is applied around a car body to investigate the wind throb phenomenon. The computational scheme and the modeling method of the car body is first described. A flow visualization test in a water tunnel was completed for the simple car body shape to compare against the numerical procedure. The numerical and the visualized results compared well and the numerical simulation method employed was considered to be a reliable tool to analyze the wind throb phenomenon. Calculated results of pressure and vorticity distribution in the sunroof opening were analyzed with the spectrum of pressure fluctuation at the sunroof opening with and without a deflector.
Technical Paper

EGR Technologies for a Turbocharged and Intercooled Heavy-Duty Diesel Engine

1997-02-24
970340
In this study three EGR methods were applied to a 12 liter turbocharged and intercooled Dl diesel engine, and the exhaust emission and fuel consumption characteristics were compared. One method is the Low Pressure Route system, in which the EGR is taken from down stream of the turbine to the compressor entrance. The other two systems are variations of the High Pressure Route system, in which the EGR is taken from the exhaust manifold to the intake manifold. One of the two High Pressure Route EGR systems is with back pressure valve located at downstream of the turbine and the other uses a variable geometry(VG) turbocharger. It was found that the High Pressure Route EGR system using VG turbocharger was the most effective and practical. With this method the EGR area could be enlarged and NOx reduced by 22% without increase in smoke or fuel consumption while maintaining an adequate excess air ratio.
Technical Paper

Development of Gasoline Direct Injection Engine

1997-02-24
970541
The major problems of the various mixture formation concepts for direct injection gasoline engines that have been proposed up to the present were caused by the difficulties of preparing the mixture with adequate strength at spark plug in wide range of engine operating conditions. Novel combustion control technologies proposed by Mitsubishi is one of the solution for these problems. By adopting upright straight intake ports to generate air tumble, an electromagnetic swirl injector to realize optimized spray dispersion and atomization and a compact piston cavity to maintain charge stratification, it has become possible to achieve super-lean stratified combustion for higher thermal efficiency under partial loads as well as homogeneous combustion to realize higher performance at full loads. GDI™ (Gasoline Direct Injection) engine adopting these technologies is developed. At partial loads, fuel economy improvement exceeding 30 % is realized.
Technical Paper

Reduction of Exhaust Emission with New Water Injection System in a Diesel Engine

1996-02-01
960033
In this study a new water injection system was applied to an 11 liter naturally aspirated DI diesel engine in order to reduce exhaust emissions. In this system, the water and fuel were arranged in the injection nozzle during the time between injections as fuel, water and then fuel. The fuel and water were then injected into the cylinder in that order. The tests were conducted at several engine operating conditions from the Japanese 13 mode test cycle to clarify effects of water injection on exhaust emissions and fuel consumption. The results showed that NOx reduction was directly proportional to the relative amount of water injection, regardless of engine speed and load. By using the optimal relative amount of water injection at each engine operating condition, total NOx and particulate matter (PM) in the Japanese 13 mode test cycle were reduced by 50% and 25%, respectively, without a fuel consumption penalty.
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